Article

# Use of charge-transfer complexation in the spectrophotometric analysis of certain cephalosporins

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## Abstract

Three simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of cephapirin sodium (1), cefazoline sodium (2), cephalexin monohydrate (3), cefadroxil monohydrate (4), cefotaxime sodium (5), cefoperazone sodium (6) and ceftazidime pentahydrate (7) in pure form as well as in their pharmaceutical formulations. The methods are based on the reaction of these drugs as n-electron donors with the σ-acceptor iodine, and the π-acceptors: 2,3-dichloro-5,6-dicyano-p-benzo-quinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). Depending on the solvent polarity, different coloured charge-transfer complexes and radicals were developed. Different variables and parameters affecting the reactions were studied and optimized. The obtained charge-transfer complexes were measured at 364 nm for iodine (in 1,2-dichloroethane), 460 nm for DDQ (in methanol) and 843 nm for TCNQ (in acetonitrile). Ultraviolet–visible, infrared and 1H-nuclear magnetic resonance techniques were used to study the formed complexes. Due to the rapid development of colours at ambient temperature, the obtained results were used on thin-layer chromatograms for the detection of the investigated drugs. Beer's plots were obeyed in a general concentration range of 6–50, 40–300 and 4–24 μg ml−1 with iodine, DDQ and TCNQ, respectively, with correlation coefficients not less than 0.9989. The proposed procedures could be applied successfully to the determination of the investigated drugs in vials, capsules, tablets and suspensions with good recovery; percent ranged from 96.47 (±1.14) to 98.72 (±1.02) in the iodine method, 96.35 (±1.62) to 98.51 (±1.30) in the DDQ method, and 95.98 (±0.78) to 98.40 (±0.87) in the TCNQ method. The association constants and standard free energy changes using Benesi–Hildebrand plots were studied. The binding of cephalosporins to proteins in relation to their molar absorptivities was studied.

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... Several methods have been described for the quantitative determination of cephalosporins included Spectrophotometry [10,11,12], spectrofluorimetry [13], High performance liquid chromatography (HPLC)14151617181920, potentiometry [21] and voltammetry [22]. However, most of the HPLC methods were time-consuming, tedious, and dedicated to sophisticated and expensive analytical instruments. ...
... El-Obeid et al., [24] reported that ampicillin, amoxicillin, cephalexin, cefadroxil and cefaclor can be determined in their pharmaceutical preparations using colorimetric method based on measuring the color obtained when the alkaline degradation product of the drug was allowed to react with ascorbic acid. Beer's law was obeyed over the range3456789101112131415 µg mL -1 , and the product was measured at 410 nm. Saleh et al., [12] described three spectrophotometric procedures for the analysis of cephapirin sodium, cefazoline sodium, cephalexin monohydrate, cefadroxil monohydrate, cefotaxime sodium, cefoperazone, and ceftazidime pentahydrate in pure form as well as in their pharmaceutical formulations. ...
... Beer's law was obeyed over the range3456789101112131415 µg mL -1 , and the product was measured at 410 nm. Saleh et al., [12] described three spectrophotometric procedures for the analysis of cephapirin sodium, cefazoline sodium, cephalexin monohydrate, cefadroxil monohydrate, cefotaxime sodium, cefoperazone, and ceftazidime pentahydrate in pure form as well as in their pharmaceutical formulations. The methods were based on the reaction of these drugs as n-electron donors with the sigma-acceptor iodine, and the pi-acceptors: 2,3-dichloro- 5,6-dicyano-p-benzo-quinone (DDQ) and 7,7,8,8- tetracyanoquinodimethane (TCNQ). ...
Article
Full-text available
Cephalosporins are the most commonly prescribed β-lactam antibiotics. Spectrophotometry is probably the most convenient analytical technique for routine analysis, because of its inherent simplicity, low cost and wide availability in quality control laboratories. Several papers have been presented in recent years regarding the development and validation for spectrophotometry methods for analysis of cephalosporins in pharmaceutical formulations. In this review article, various spectroscopic methods for analysis of cephalosporins are presented and discussed.
... The use of micro-well plates can reduce both consumption and cost of organic solvents by 50-fold as well as decreasing the risk of human exposure to toxic solvents [26,27]. Although, several analytical methods were reported concerning the use of 2, 3dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) as a charge transfer (CT) reagent for spectrophotometric analysis [26][27][28][29][30][31], only three reports were found for its use in spectrofluorometric analysis [32][33][34]. Mahmoud et al. [28] has already used the combination of OMZ/DDQ in the development of conventional colorimetric analysis of OMZ in its dosage forms. ...
... The effect of temperature on the formation of the fluorescent product was investigated by following the fluorescence development at different temperatures (20,25,30,35,40, and 50°C) using fixed concentrations of OMZ and DDQ. The results indicated that room temperature (25 ± 2°C) was the ideal selection and higher temperatures was found to decrease the fluorescence intensity. ...
Article
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A high-throughput 96-microwell plate fluorometric method was developed and validated to determine omeprazole (OMZ) in its dosage forms. The method was based on the charge-transfer (CT) sensitized fluorescence reaction of OMZ with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ). This fluorescence reaction provided a new approach for simple, sensitive and selective determinations of OMZ in pharmaceutical preparations. In the present method, the fluorescence reaction was carried out in 96-microwell plates as reaction vessels in order to increase the automation of the methodology and the efficiency of its use in quality control laboratories. All factors affecting the fluorescence reaction were carefully studied and the conditions were optimized. The stoichiometry of the fluorescence reaction between OMZ and DDQ was determined and the reaction mechanism was suggested. Under the optimum conditions, the linear range was 100-6000 ng/ml with the lowest LOD of 33 ng/ml. Analytical performance of the proposed assay, in terms of accuracy and precision, was statistically validated and the results were satisfactory; RSD was <2.6 % and the accuracy was 98.6-101.6 %. The method was successfully applied to the analysis of OMZ in its dosage forms; the recovery values were 98.26-99.60 ± 0.95-2.22 %. The developed methodology may provide a safer, automated and economic tool for the analysis of OMZ in quality control laboratories.
... The complexation methods based on the charge-tranfer for determination of cefadroxil (Saleh et al., 2001), cefpodoxime . (El-Sattar et al., 2001); or based on formation of ion pairs for determination of cefadroxil (Prasad et al., 2004;Naveed et al., 2014), cefaclor (Avadhanulu et al., 1996), cefadroxil and cefaclor (Salem and Askal 2002), cefixime (Siddalinga et al., 2012;Ivama et al., 1999), cefpodoxime (Siddalinga et al., 2012) were also reported. ...
... To our best knowledge and after reviewing the literatures, the spectrophotometric and spectrofluorimetric methods based on redox reactions suffer from lack of suitable selectivity (Daabees et al., 1998;Aly et al., 1994;Chilukuri et al., 1997;Salem and Saleh, 2002;Gamal, 1996;Issopoulos, 1989, Gamal et al., 2002Issopoulos, 1989;Badawy, et al., 1993;Nabi et al., 1997;El-Shaboury et al., 2010;Shah and Pundarikakshudu, 2006;Morelli and Peluso, 1985;Elazazy et al., 2003;Al-Momani, 2001;Ashok et al., 2011). Although some of the visible measurements, after metal complexation and/or complexation methods based on the charge-tranfer formation with individual cephalosporins, are have highly sensitive (Badawy et al., 1993;Dimitrovska et al., 1996;Salem, 2004;Khater and Ibrahim, 1993;Ramadan et al., 2013;Rao et al., 2004;Hosny, 2014;Elazazy et al., 2004;Saleh et al., 2001;Subbayamma and Rambabu, 2010;El-Sattar et al., 2001;Prasad et al., 2004;Naveed et al., 2014;Avadhanulu et al., 1996;Salem and Askal, 2002;Siddalinga et al., 2012;Ivama et al., 1999) however some cephalosporins need tedious experimental and time consuming procedure such as use of chloroform for extraction of the reaction product (Naveed et al., 2014;Ivama et al., 1999). In addition, the other reported spectrofluorimetric methods may require more expensive reagents such as fluorescamine (Hefnawy et al., 1999;Chaudhari and Patel 2014). ...
Article
Full-text available
A selective spectrofluorimetric method was described for determination of some cephalosporins namely, cefadroxil, cefaclor, cefixime, cefpodxime, and cefepime. These drugs were utilized as a source of amine group to react with acetylacetone and formaldehyde reagents via a Hantzsch reaction. The fluorescence intensity of the reaction products were measured at an emission wavelength of482 nm after excitation at a wavelength of 415 nm. The linear calibration graphs were obtained in the concentration ranges of 1-100 µg/mL for either cefadroxil or cefaclor and 1-50 µg/mL for the other three drugs. The limits of detection and quantitation were in the concentration range of 0.31-0.82 and 0.72-2.5 µg/mL, respectively. The percent of relative standard deviation (at 50 µg/mL concentration level, n = 5) were in the range of 0.41-1.70% and 1.51-1.95% for intra-day and inter-day precision, respectively. The method was successfully applied for the assay of some dosage forms of the cited drugs and the results obtained were comparable with those obtained by a reported method.
... However, the direct determination of CFDL was observed at 264 nm by spectrophotometer but it was semi quantitative [28]. Thus, different chemical reagents like 4-amino anti-pyrene, N-bromosuccinide and tetracyanoquinoid-methane were used to enhance the selective and sensitive determination of CFDL by spectrophotometry [29][30][31]. However, 2,4-dinitrophenylhydrazine (DNP) is most effective derivatizing agent for the quantitative analysis of different drugs [32][33][34]. ...
Article
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The goal of this research is to verify the proposed nano-silver amalgam paste electrode (Ag-nano-SPE) method to compare with a spectrophotometric technique based on derivatization with potassium periodate (KIO4 ), 2,4-dinitrophenyl hydrazine (DNP) and sodium hydroxide (NaOH) for the estimation of cefadroxil (CFDL) by square wave adsorptive stripping voltammetry (SWAV). The different parameters of both methods were optimized in detail separately and then compared their efficiency, selectivity, sensitivity and applications. The SWAV produced a reduction peak with a precise definition at -0.160 V while measuring CFDL in 0.04 molL-1 Britton–Robinson buffer at pH 4, accumulation potential (0.5 V), accumulation time (10 sec), and with stirring rate of 200 rpm. Whereas, the CFDL was measured at 515 nm (λmax) by UVVisible spectrophotometer after the derivatization by using 1.5 mL of 0.5 mM DNP, 1.5 mL of 6.52 mM KIO4 and 0.5 mL of 10 M NaOH solution at room temperature. The linear response for CFDL was found using the SWAV and spectrophotometric techniques along a linear dynamic range from 0.033 - 0.304 and 0.051 - 1.376 µM, respectively. However, the precision, detection limit and quantification limit of SWAV for CFDL in the samples and standards significantly lower (p <0.01) as compared to spectrophotometric method. This indicates that the SWAV is more sensitive and selective than the spectrophotometric technique for regular CFDL analysis.
... Ion pair formation, initially investigated by the physical chemistry has been found extremely interesting for the chemical analysis, including pharmaceutical analysis. Reported spectrophotometric methods of these three antibiotics includes complex formation with quinalizarin [12], eosin Y [13], rose Bengal [14], chloranilic acid and 7,7,8,8-tetracyanoquinodimethane [15], bromocresol purple and bromecresol green [16], ammonium vanadate [17], p-nitro phenol [18], Mo(V)-thiocyanate [19], p-dimethyl aminobenzaldehyde [20], molybdenum blue [21], Sodium 1,2-napthoquinone-4-sulphonate [22], p-benzaquinone [23], iodine, 2,3-dichloro-5,6-dicyano-1,4benzoquinone and 7,7,8,8-tetracyanoquinodimethane [24]. ...
Article
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Objective: Simple and rapid methods have been developed for the determination of azithromycin, sparfloxacin and cephalexin monohydrate in bulk and pharmaceutical formulations. Method: These methods were based on the formation of bluish-green ion pair complexes of these antibiotics with bromophenol blue (BPB). Acetonitrile was used as a solvent for azithromycin and sparfloxacin whereas methanol-acetonitrile medium for cephalexin monohydrate. Results: 2:1 complexes were formed between the drug and reagent almost instantaneously with absorption maxima 595 nm, 620 nm, 600 nm for the three drugs respectively. Different parameters such as effect of time, effect of reagent concentration were optimised. Under optimum conditions, calibration curves were found to be linear over the range of 0-50 μg mL-1 for azithromycin, 10-80 μg mL-1 for sparfloxacin and 10-170 μg mL-1 for cephalexin monohydrate respectively. The detection limits were found to be 0.10 μg mL-1 , 0.21 μg mL-1 and 1.69 μg mL-1 with Sandell's sensitivity 0.0559 μg cm-2 , 0.1034 μg cm-2 and 1.3920 μg cm-2 respectively for the three drugs. Stability constant (log K) was found to be 6.19 ± 0.04, 5.00 ± 0.07 and 4.05 ± 0.05 showing high stability of the complexes. Molar absorptivity was found to be 1.369×10 4 L mol-1 cm-1 , 3.774×10 3 L mol-1 cm-1 and 2.620×10 2 L mol-1 cm-1 with Gibb's free energy change-2.725×10 3 kJ mol-1 ,-2.393×10 3 kJ mol-1 and-1.938×10 3 kJ mol-1. These methods were subjected to analytical quality control. Accuracy, precision, recovery and interference studies have been carried out. Conclusion: The proposed methods were successfully applied to the determination of these drugs in their pharmaceutical formulations and human urine samples.
... Some analytical methods are described in the literature for analysis of cefazo lin sodium in raw material and finished product. Among these are found bromo metry methods[11]; Colorimet ry,[12]; highperformance liquid chro matography[13][14][15][16][17][18][19][20]; capillary electrophoresis[21][22]; ultravio let (UV) and visible (VIS) spectrophotometry[23][24][25][26][27]; fluorimetry[28]; refractive index[29]; polarography[30]; chemilu minescence[31]; radiosensibility[32] and voltammetry[33]. However, many of these methods require pre-treat ment of the sample, formation of metal co mplexes, drug degradation using sulfuric acid, among other time-consuming co mplex procedures, which require sophisticated equipment, high costs or use of large amounts of organic solvents, which are toxic for the operators and the environment. ...
... Beer's law plots were linear with small intercept (0.0101-0.0277) and slopes (0.0012-0.0072) values in the concentration ranges were presented in Table 1. The correlation coefficient, intercepts and regression equation for the proposed procedures were listed in Table 1 28 . The apparent molar absorptivities found to be in the order of 3.0×10 2 and 5.39×10 2 L mol !1 cm !1 with the Sandell sensitivities of 0.0126 and 0.0118 μg cmG 2 for ESL and TRA drugs, respectively, as calculated from Beer's law ( Table 1). ...
... According to literature surveys, there are different analytical methods reported for the determination of CA and CT. It includes UV-Visible spectroscopy [3][4][5][6][7][8][9][10][11][12], chemiluminescence [13], near infrared spectroscopy [14], potentiometry [15], polarography [16,17], HPLC [18][19][20][21][22][23][24][25][26], gel filtration chromatography [27], HPLC [28], capillary zone electrophoresis [29], LC-MS [30,31], and MS [32] methods. But no analytical methods are reported for the determination of CA and CT in dry syrup formulation using the mobile phase Triethylamine: Methanol: Acetonitrile: Ultra-Pure Water (2:10:20:68 v/v%) by HPLC (High Performance liquid chromatography). ...
Article
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Determination of two generation Cephalosporins (Cefuroxime Axetil and Cefixime Trihydrate) in pharmaceutical dosage forms was carried out employing High Perfeormance Liquid Chromatographic using isocratic separation. Separation was performed on an Enable C18 column (250 mm × 4.6 mm, 5.0 μm) using Triethylamine: Methanol: Acetonitrile: Ultra-Pure Water (2:10:20:68 v/v%) as the mobile phase at a flow rate of 1.0 ml/min. The PDA detection wavelength was set at 265 nm. The linearity was observed over a concentration range of 0.1-80 μg/ml for HPLC method (correlation coefficient=0.999). The developed methods were validated according to ICH guidelines. The relative standard deviation values for the method precision studies were <2%, and the accuracy was >99%. The developed method was used successfully for the determination of Cefuroxime Axetil, Cefixime Trihydrate, in Capsule, Tablet and dry syrup formulations.
... Some analytical methods are described in the literature for analysis of cefazo lin sodium in raw material and finished product. Among these are found bromo metry methods [11]; Colorimet ry, [12]; highperformance liquid chro matography [13][14][15][16][17][18][19][20]; capillary electrophoresis [21][22]; ultravio let (UV) and visible (VIS) spectrophotometry [23][24][25][26][27]; fluorimetry [28]; refractive index [29]; polarography [30]; chemilu minescence [31]; radiosensibility [32] and voltammetry [33]. However, many of these methods require pre-treat ment of the sample, formation of metal co mplexes, drug degradation using sulfuric acid, among other time-consuming co mplex procedures, which require sophisticated equipment, high costs or use of large amounts of organic solvents, which are toxic for the operators and the environment. ...
Article
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A simp le, fast and reproducible UV Spectrophotometric method was developed and validated for quantification of cefazolin sodium in pharmaceutical form powder for injectable solution, the method proved effective, easy applicability, low cost, besides it does not generate toxic wastes to the operator and the environment, corroborating with the routine analysis of quality control to ensure the therapeutic efficacy of the drug already marketed. The method presented being capable to detect and quantify the drug obtaining satisfactory results regarding specificity, precision, accuracy and robustness, linear range of 8 to 28 µg/ mL, showing correlation coefficient of 0.9999 when analyzed in the wavelenght λ=270 n m spectrophotometer.
... In order to check the validity of the proposed methods, CEPM, CFZS and CFLS were determined in some commercial formulations (table 4) gives the results of the determination from which it is clear that there is close agreement between the results obtained by the proposed methods and the label claim. The results were also compared statistically by a student's t-test for accuracy and variance ratio F-test for precision with those of the reported methods (1,2) and (3) at 95% confidence levels. The calculated t-and F-values (table 4) did not exceed the tabulated values (t = 2.44, F = 5.05) and indicated that there was no significant difference between the proposed method and the reported method. ...
Article
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Objectives: cefazolin sodium and cefalothin sodium are the broad spectrum of antibiotics, are mainly used to control gram positive and gram negative bacterial infections. Cefepime is used to treat moderate-severe nosocomical pneumonia, infections caused by multi resistant microorganisms.(eg. pseudomonos aeruginosa) and empirical treatment of febrile neutropenia. The objective of our method is to develop an effective, simple and sensitive spectrophotometric method for the assay of the above mentioned drugs in both tablet and in pharmaceutical dosage forms. Methods: The method is based on the reaction of cephalosporin’s with ninhydrin reagent in the presence of sodium molybdate by maintaining the pH (5.5) using citrate buffer. The reaction is carried out at a temperature of 1000C for 10 min for CEPM, 15 min for both CFZS and CFLS. The resulting Ruhemann’s purple product having the absorption maximum at 570 nm is measured against the reagent blank. Results: Beer’s law is obeyed in the concentration range of (1-10 μg/ml) for cefepime, (2-20 μg/ml) for cefazolin sodium and (6-40 μg/ml) for cefalothin sodium respectively. The correlation coefficient’s (r2), molar absorptivity (€), Sandell’s sensitivity (s), Limit of detection (LOD) and quantification limits (LOQ) for the studied drugs were calculated. Recovery studies shows that this method is accurate and can be successfully employed for the determination of the studied cephalosporin’s. Conclusion: Recovery studies, optical parameters and statistical comparisons justify that the present proposed method can be applied to routine drug formulation in pure and dosage forms and can be recommended for routine analysis and also for quality control of these drugs. © 2015, International Journal of Pharmacy and Pharmaceutical Sciences. All Rights Reserved.
... Cephalosporins are derivatives of 7-aminocephalosporanic acid (7-ACA) composed of a b-lactam ring fused with a dihydrothaizine ring (Fig. 1), but differ in the nature of substituent at the 3-and/or 7-positions of the cephem ring (Delgad and Wilson, 2004;Dollery,1999). Several methods have been described for the quantitative determination of cephalosporins included spectrophotometry (Ayad et al.,1999;Saleh et al., 2001Saleh et al., , 2003, spectrofluorimetry (Aly et al.,1996), high performance liquid chromatography (Baranowska et al., 2006;Chen et al., 2003;De Diego Glari´a et al., 2005;Misztal, 1998;Moore et al.,1991;Sørensen and Snor, 2000;Tsai and Chen, 2000), potentiometry, (Lima et al., 1998) and voltammetry (Ö zkan et al., 2000). These methods were time-consuming, tedious, and dedicated to sophisticated and expensive analytical instruments . ...
Article
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A simple, accurate, and precise spectrophotometric method has been proposed for the determination of three cephalosporins, namely: cefixime (cefi), cephalexine, (ceph) and cefotaxime (cefo) in pharmaceutical formulations. Proposed method is based on the derivatization of cephalosporins with 1,2-naphthoquinone-4-sulfonic (NQS). The optimum experimental conditions have been studied. Beer’s law is obeyed over the concentration of 0.5–3, 0.8–2.8, and 0.2–1.2 μg/mL for cefi, ceph, and cefo, respectively. The detection limits were 0.12, 0.168, and 0.0465 μg/mL for cefi, ceph, and cefo, respectively, with a linear regression correlation coefficient of 0.9993, 0.9993, and 0.9994 and recovery in range from 96.5–102.3, 96.04–102.22, and 97.09–99.3 for cefi, ceph, and cefo, respectively. Effects of pH, temperature, reaction time, and NQS concentration on the determination of cefi, ceph, and cefo, have been examined. This method is simple and can be applied for the determination of cefi, ceph, and cefo in pharmaceutical formulations in quality control laboratories.
... These bands are the characteristic absorption band of DDQ radical anion. [15] Further, the gradual decrease in intensity of these CT bands observed in the 400 to 600 nm spectral regions could be due to the consumption of the ion pair. Three peaks at 423, 442, and 457 nm disappeared and gave a stable peak at 441 nm, and there was not much difference between the peaks at 547 and 587 nm ( Figure 1B). ...
Article
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The solid charge transfer (CT) complexes that have been formed from the reactions of donor benzidine (BZ) and the π-acceptors such as 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and chloronil (CHL) have been studied and characterized experimentally and theoretically. The experimental work which includes the use of UV-visible spectroscopy to identify the CT band of the CT-complex. The composition of the complexes has been investigated successfully by using spectrophotometric titration and Job method of continuous variation to be 1:1. Furthermore, to calculate the formation constant and molar extinction coefficient, we have used the Benesi-Hildebrand equation. Infrared and proton nuclear magnetic resonance spectral studies were used to characterize and confirm the formation of CT-complex. The experimental studies were well supported by quantum chemical simulations by using density functional theory. The computational analysis of molecular geometry, Mulliken charges, and molecular electrostatic potential surfaces of reactants and complexes is very much helpful in assigning the CT route. The C═O bond length of DDQ and CHL increased upon complexation with BZ. We have also observed that the substantial amount of charge has been transferred from BZ to DDQ and CHL in the process of complexation. An excellent consistency has been achieved between experimental and theoretical results.
... The determination of cephalosporins has received much attention from researchers and several methods exist in literature for the quantitation of brands of various cephalosporins. Some of the methods that have been described for the quantitative determination of 12,13,14 cephalosporins include; spectrophotometry , 15 16,17,18,19,20,21,22 23 spectrofluorimetry , HPLC , potentiometry 24 and voltammetry. However, most of the HPLC methods were described as time-consuming, tedious, and dedicated to sophisticated and expensive analytical instruments. ...
... 10 Cefazolin sodium has some analytical methods described in official compendia such as British, 11 European, 12 Japanese, 13 Portuguese 14 and US 15 pharmacopeias. In the literature, several methods have been described for the qualitative 16 and quantitative analysis of cefazolin sodium, included spectrophotometry, [17][18][19][20][21][22][23][24][25][26][27][28][29] high-performance liquid chromatography [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] and voltammetry. 48 However, most of them were time-consuming and dedicated to sophisticated and expensive analytical instruments. ...
Article
Full-text available
Cefazolin sodium, a β-lactam antimicrobial agent belonging to the first generation cephalosporins, has a broad spectrum of action, acting against gram positive and gram negative bacteria. Stands out over other cephalosporins for its ability to also act against some species of Enterobacter, and have a long half-life, thus reducing the frequency of administrations. A simple, fast and reproducible method by visible spectrophotometry was developed and validated for quantification of cefazolin sodium in the lyophilized powder. This technique is widely used in the pharmaceutical industry due to its ease of execution, low cost, safety and high precision and accuracy. It has been employed in the quality control routine of numerous pharmaceuticals in order to identify them and quantify their active principles. The method was capable of detecting and quantifying the cefazolin sodium obtaining satisfactory results regarding selectivity, precision, accuracy and robustness, on linear range of 32.0 to 92.0 µg mL-1 , showing the correlation coefficient of 0.9993 when analyzed at 767 nm. Due to the environmental impacts caused by global economic development, green chemistry has come up with a proposal to minimize and/or eliminate the use of harmful solvents, which generate large amounts of toxic waste to the environment and the health of operators, as well as reducing expenses with costly processes. The proposed method does not use toxic solvent, proving to be effective, low cost, easy to apply and safe for the analyst and environment.
... The CT-complex formation was confirmed from the appearance of simultaneous reddish brown color upon mixing the donor with acceptor solutions. This reddish brown color is mainly attributed to the formation of a radical anion of DDQ [24]. The existence of this radical was confirmed by polymerization of acrylonitrile [25]. ...
Article
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A charge-transfer (CT) complex that forms from the reaction of the donor 4-amino aniline (4AA) and the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) have been studied and characterized experimentally and as well as theoretically at room temperature. The experimental work includes the application of UV–visible spectroscopy to identify the CT band of the CT-complex. The composition of the complex has been investigated using spectrophotometric titration and Job’s method of continuous variation and found to be 1:1. Furthermore, to calculate the formation constant and molar extinction coefficient, we have used the Benesi–Hildebrand equation. Infrared, ¹H NMR, ¹³C NMR and mass spectral studies were used to characterize and confirm the formation of the CT-complex. The experimental studies were supported by quantum chemical simulations using density functional theory. The computational analysis of molecular geometry, Mulliken charges, and molecular electrostatic potential surfaces of reactants and complexes are helpful in assigning the CT route. The C=O bond length of DDQ increased upon complexation with 4AA. We have also observed that a substantial amount of charge has been transferred from 4AA to DDQ in the process of complexation. An excellent consistency has been achieved between experimental and theoretical results.
... Many studies are carried out on UV-visible spectrophotometric for the identification and quantification of cefadroxil [16][17][18][19][20][21][22], however, in none of the studies has the technique been presented in microplates, which makes the choice of the method safe to be performed and propitious for the continuity of analyzes that contribute to green analytical chemistry. Ultraviolet and visible spectrophotometryis one of the most frequently employed technique in pharmaceutical analysis [23][24][25][26][27][28][29]. ...
Article
Cefadroxil, an oral antimicrobial, presents few techniques optimized for the reduction of solvents and toxic residues and/or non-use of them. So, a quantitative, new and miniaturized method for determination of cefadroxil monohydrate in capsules has been developed and validated by spectrophotometric method in the visible region according to the international guidelines. The analyzes were performed using microplates containing 96 wells, 1 % of phenolphthalein and sodium hydroxide 0.1 M as reagent at 552 nm. The method was (i) linear in the range of 15-115 µg mL-1, (ii) selective when comparing standard, sample, adjuvants and color reagent, (iii) precise with deviations below 4 %, (iv) accurate when comparing the proposed method with the HPLC method, (v) robusts by making small and deliberate modifications to the method, (vi) besides being fast, low cost, eco-friendly and generates minimal amount of waste. The method can be applied to the routine quality control of cefadroxil monohydrate in capsules and an effective and accessible alternative that contemplates the concepts of current and sustainable green analytical chemistry.
... Potential symptoms from significant exposure include watery diarrhea, central nervous system depression and unconsciousness [8]. Technically, radical ion pairs are produced on the acceptor when an electron transfers from the donor to the quinine molecule [9][10][11]. Quinones are readily available -acceptors and their charge shift complexes have been extensively studied [12][13][14][15][16]. ...
Article
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A bioactive donor, 1-(2-methylbenzyl)piperazine is used to synthesize a new charge transfer complex (CTC) with the π-acceptor p-chloranil (p-CHL), which is characterized spectrophotometrically. The quantitative estimation of electronic interaction of the acceptor with the donor has been examined in acetonitrile (AN). The 1:1 composition of the CTC is confirmed by Jobs’ method of continuous variation and spectrophotometric (at $$\lambda$$max 554 nm) methods at 298 K. The Benesi–Hildebrand method gives the formation constant (KCT) and molar extinction coefficient (ε) values of CTC. The spectral analysis was used to characterize CTC and its stability in solution and in the crystalline form. A DNA binding study of the CT-complex was carried out using UV–visible spectroscopy. A density functional theory (DFT) study of the CTC (gas phase/PCM) at using the B3LYP functional and 6-31G(d,p) basis set supports the experimental work. The optimization of the frontier molecular orbital surfaces was carried out by using the DFT-gasphase/PCM correlation methods. Mulliken atomic charges and reactive parameters of acceptor and donor recommend the MBPZ acts as a good electron donor and p-CHL acts as a good electron acceptor to form a highly stable electron transfer complex.
... The determination of cephalosporins has received much attention from researchers and several methods exist in literature for the quantitation of brands of various cephalosporins. Some of the methods that have been described for the quantitative determination of 12,13,14 cephalosporins include; spectrophotometry , 15 16,17,18,19,20,21,22 23 spectrofluorimetry , HPLC , potentiometry 24 and voltammetry. However, most of the HPLC methods were described as time-consuming, tedious, and dedicated to sophisticated and expensive analytical instruments. ...
Article
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Background: Several factors can affect the effectiveness of a drug in therapy. One of such is the presence of impurities. Objectives: Based on the current useful utility status of ceftriaxone injection as an antibacterial agent, a comprehensive impurity profiling of thirteen brands was carried out in order to provide a basis for specifying appropriate storage conditions. Methods: The profiling was carried out by developing a new liquid chromatographic method with UV detection. Factors that could affect the separation method such as elution mode, pH, flow rate, detection wavelength and type of organic modifier were studied. Validation studies comprising calibration curve, LOD and LOQ determination, accuracy and repeatability were determined. The method was successfully applied to the determination of ceftriaxone and impurities in 13 brands of ceftriaxone injections. Results: The developed method involved separation of ceftriaxone and major impurities within 15 minutes using gradient elution with KHPO (pH 7.5) and methanol (flow rate, 1 mL/min). Separation was achieved on 2 4 2a C-18 column at 220 nm. Linearity was obtained within the range 7.8 – 250 ìg/mL (r = 0.9996) with LOD and LOQ as 74.56 and 225.9 ng/mL respectively. Relative errors from the intra- and inter-day assessment were generally less than 2%. All the brands complied with the content BP specification of 92-108% of ceftriaxone. However, the impurities content in all the 13 brands were far higher than the 0.2% specified by ICH for the dose of the drug. Conclusion: There is need for measures to adequately control storage conditions of the injection in order to limit impurities content.
... In order to check the validity of the proposed methods, CEPM, CFZS and CFLS were determined in some commercial formulations (table 4) gives the results of the determination from which it is clear that there is close agreement between the results obtained by the proposed methods and the label claim. The results were also compared statistically by a student's t-test for accuracy and variance ratio F-test for precision with those of the reported methods (1,2) and (3) at 95% confidence levels. The calculated t-and F-values (table 4) did not exceed the tabulated values (t = 2.44, F = 5.05) and indicated that there was no significant difference between the proposed method and the reported method. ...
Research
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Objectives: cefazolin sodium and cefalothin sodium are the broad spectrum of antibiotics, are mainly used to control gram positive and gram negative bacterial infections. Cefepime is used to treat moderate-severe nosocomical pneumonia, infections caused by multi resistant microorganisms.(eg. pseudomonos aeruginosa) and empirical treatment of febrile neutropenia. The objective of our method is to develop an effective, simple and sensitive spectrophotometric method for the assay of the above mentioned drugs in both tablet and in pharmaceutical dosage forms. Methods: The method is based on the reaction of cephalosporin's with ninhydrin reagent in the presence of sodium molybdate by maintaining the pH (5.5) using citrate buffer. The reaction is carried out at a temperature of 100 0 Results: Beer's law is obeyed in the concentration range of (1-10 µg/ml) for cefepime, (2-20 µg/ml) for cefazolin sodium and (6-40 µg/ml) for cefalothin sodium respectively. The correlation coefficient's (r C for 10 min for CEPM, 15 min for both CFZS and CFLS. The resulting Ruhemann's purple product having the absorption maximum at 570 nm is measured against the reagent blank. 2 Conclusion: Recovery studies, optical parameters and statistical comparisons justify that the present proposed method can be applied to routine drug formulation in pure and dosage forms and can be recommended for routine analysis and also for quality control of these drugs.), molar absorptivity (€), Sandell's sensitivity (s), Limit of detection (LOD) and quantification limits (LOQ) for the studied drugs were calculated. Recovery studies shows that this method is accurate and can be successfully employed for the determination of the studied cephalosporin's.
... According to literature surveys, there are different analytical methods reported for the determination of CA and CT. It includes UV-Visible spectroscopy [3][4][5][6][7][8][9][10][11][12], chemiluminescence [13], near infrared spectroscopy [14], potentiometry [15], polarography [16,17], HPLC [18][19][20][21][22][23][24][25][26], gel filtration chromatography [27], HPLC [28], capillary zone electrophoresis [29], LC-MS [30,31], and MS [32] methods. But no analytical methods are reported for the determination of CA and CT in dry syrup formulation using the mobile phase Triethylamine: Methanol: Acetonitrile: Ultra-Pure Water (2:10:20:68 v/v%) by HPLC (High Performance liquid chromatography). ...
Research
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phenol
... Furthermore, these reactions help us to understand biological and chemical processes. In principle, the radical anions are produced on the acceptor when electron transfer from donor to quinone molecule occurs, forming radical ion pairs [18][19][20]. The DDQ is a readily available important π-acceptor and its charge transfer complexes have been extensively studied with available donors [21][22][23][24][25][26]. ...
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This research discusses the charge transfer (CT) complex of 1-benzoylpiperazine (1-BP) as a donor with the π-acceptor of 2, 3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) which has been studied spectrophotometrically in acetonitrile (ACN) at different temperatures. The 1:1 molecular composition of the CT complex was confirmed by applying Job’s continuous variation and photometric titration methods and the Benesi–Hildebrand equation is used to calculate the formation constant (KCT) and molar extinction coefficient (ε). The thermodynamic parameters standard enthalpy (ΔH°), standard entropy (ΔS°) and standard Gibbs energy (ΔG°) were calculated by using van’t Hoff equation. These results indicate that the CT complex formation is exothermic. The computational study of the CT complex, using density functional theory, supports the experimental work. The molecular geometry, molecular electrostatic potential maps, characterization of the frontier molecular orbital surfaces, Mulliken partial atomic charges and reactive parameters of the acceptor and donor are helpful in assigning the CT route. The charge transfer in the 1-BP–DDQ complex and its high stability are evidenced through both experimental and theoretical studies.
... Cefoperazone and Sulbactam have an official status in United States Pharmacopoeia (USP), British Pharmacopoeia (BP) and Indian pharmacopeia (IP) individually [3][4][5], but their combination is not official in any of the pharmacopeia. Literature survey reveals that methods like Spectrophotometric methods [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], HPLC [22][23][24][25][26], HPTLC [27,28] and LC-MS/MS [29][30][31][32] have been reported for the estimation of Cefoperazone and Sulbactam in the pharmaceutical dosage forms. To the best of our knowledge, there is no stability indicating HPLC method reported for the estimation of impurities for their dosage form (Fig. 1). ...
Article
Background Cefoperazone Sulbactam injection is a cephalosporin antibiotic with a β- lactamase inhibitor used in the treatment for intra abdominal infections, Urinary track infections, surgical infections, etc. The combination is not official in any of the pharmacopeia for their content and impurities determination. Introduction The present study involves the development of a simple, rapid, accurate, sensitive and stability indicating RP-HPLC method for the quantitative estimation of Cefoperazone Sulbactam mixture and its impurities in bulk and pharmaceutical dosage forms. Methods 0.005 M Tetrabutyl ammonium hydroxide buffer solution pH adjusted to 6.80 and Acetonitrile combination has been used in a gradient programme with a flow rate of 1.0 ml/min. The retention time of Cefoperazone and Sulbactam were observed at around 8.5 and 19.5 minutes respectively. The UV detection was carried out at a wavelength of 230 nm. The chromatographic separation was achieved using Waters xbridge C18-150*4.6 mm, 3.5 µm HPLC column. The method has been validated according to the current International Council for Harmonization (ICH) guidelines for the method validation parameters such as Specificity, linearity, range, accuracy, precision, robustness and sensitivity. Results The validation results indicate that the method is specific, as the known impurities and other impurities formed during the forced degradation studies were not co-eluting with the main components. Moreover, all these impurities were found to be spectrally pure, proving the stability indicating power of the method. The linearity and range of the method is in the range of 0.01-150%, highly accurate (100.2%), precise (<1%) and robust. Conclusion The proposed method was accurate and specific for the quantitative analysis of Cefoperazone and Sulbactam and their related impurities in the sterile mixture. Hence the proposed method can be used for the quantification of impurities in routine as well as stability analysis in the development as well as quality control laboratories.
... Charge transfer reactions are considered as simple models for biochemical processes. Benzoquinone radical anions are produced from electron transfer from donor to quinone molecule forming free radical ion pairs [14][15][16]. The importance of DDQ, a famous and readily available π-acceptor, is well established and its charge transfer complexes have been the subject of extensive studies with different donors [17][18][19][20][21][22][23]. ...
Article
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The charge transfer complex of benzhydryl piperazine as donor with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone has been studied spectrophotometrically in acetonitrile medium at different temperatures. On mixing the donor with acceptor, a reddish brown colored charge transfer complex is formed. Electronic absorption spectra of the complex show charge transfer bands at 587, 546 and 457 nm. The molecular composition of the complex was studied by applying Job’s continuous variation and spectrophotometric titration methods. These results support the formation of the complex in a 1:2 ratio. The Benesi–Hildebrand equation has been applied to compute the formation constant and molecular extinction coefficient. Thermodynamic parameters of the charge transfer complexation reaction (standard entropy, standard enthalpy and standard Gibbs free energy) have been calculated. The results of the spectrophotometric study demonstrated that the charge transfer complex formation is endothermic. The computational studies of the charge transfer complex were performed by using the Gaussian 09 W package of programs. The bond lengths, bond angles, dihedral angles, Mulliken atomic charges, molecular electrostatic potential maps and characterization of the highest occupied molecular orbital and lowest unoccupied molecular orbital surfaces of charge transfer complex were computed.
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Thesis
This thesis consists of six chapters: The first chapter contains a general survey of the different methods for the determination of the catecholamines (levodopa, methyldopa, dopamine and adrenaline), paracetamol and chloramphenicol, also it contains short notes on the charge transfer complex and the use of 7,7,8,8-tetracyanoquinodimethyane (TCNQ) in the spectrophotometric determination of drug compounds. The chapter two comprises the development of a spectro-photometric method for the determination of catecholamines (levodopa, methyldopa, dopamine and adrenaline) in the aqueous solution depending on the charge transfer complex formation reaction with TCNQ and the measurement of the absorbance at 612 nm. The molar absoptivity ranged from 18100 L.mol–1cm–1 for the adrenaline and 44520 L.mol–1.cm–1 for the levodopa. The accuracy (average recovery) is 100.74% and the precision (RSD) is less than 3%. The method is applied successfully for the determination of the catecholamines in their pharmaceutical preparations. The chapter three describes the development of a spectro-photometric method for the determination of catecholamines (levodopa, methyldopa and dopamine) in the ethanolic solution depending on the charge transfer complex formation reaction with TCNQ and the measurement of the quantitative enhancement of the TCNQ absorbance at 840 nm. The molar absoptivity ranged from 17420 L.mol–1.cm–1 for the dopamine and 24370 L.mol–1.cm–1 for the levodopa. The accuracy (average recovery) is 101.61% and the precision (RSD) is less than 2.5%. The method is applied successfully for the determination of the catecholamines in their pharmaceutical preparations. The chapter four describes the development of an indirect spectrophotometric method for the determination of paracetamol in the aqueous solution depending on the acidic hydrolysis of paracetamol to produce p-aminophenol which gives charge transfer complex with TCNQ and the measurement of the absorbance at 486 nm. The molar absoptivity is equal to 25670 L.mol–1.cm–1. The accuracy (average recovery) is 100.7% and the precision (RSD) is less than 1%. The method is applied successfully for the determination of the paracetamol in it's pharmaceutical preparations. The chapter five encompasses development of a spectro-photometric method for the determination of paracetamol in the acetonitrile solution depending on the charge transfer complex formation reaction with TCNQ and the measurement of the quantitative enhancement of the TCNQ absorbance at 840 nm. The molar absoptivity is equal to 26480 L.mol–1.cm–1. The accuracy (average recovery) is 102.16% and the precision (RSD) is less than 2.5%. The method is applied successfully for the assay of the paracetamol in it's pharmaceutical preparations. The chapter six describes the development of an indirect spectro photometric method for the determination of chloramphenicol in the aqueous solution depending on the reduction of the nitro group in the compound to amino group by zinc powder and concentrated hydrochloric acid which gives charge transfer complex with TCNQ and the measurement of the absorbance at 464 nm. The molar absoptivity is equal to 27570 L.mol–1.cm–1. The accuracy (average recovery) is 99.67% and the precision (RSD) is less than 1.5%. The method is applied successfully for the determination of the chloramphenicol in it's pharmaceutical preparations.
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An ultra high performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS) method for the analysis of cefazolin and cefalothin in human plasma (total and unbound), urine, and peritoneal dialysate has been developed and validated. Total plasma concentrations are measured following protein precipitation and are suitable for the concentration range of 1 to 500 µg/mL. Unbound concentrations are measured from ultra-filtered plasma acquired using Centrifree® devices and are suitable for the concentration range of 0.1 to 500 µg/mL for cefazolin and 1 to 500 µg/mL for cefalothin. The urine method is suitable for a concentration range of 0.1 to 20 mg/mL for cefazolin and 0.2 to 20 mg/mL for cefalothin. Peritoneal dialysate concentrations are measured using direct injection, and are suitable for the concentration range of 0.2 to 100 µg/mL for both cefazolin and cefalothin. The cefazolin and cefalothin plasma (total and unbound), urine and peritoneal dialysate results are reported for recovery, inter-assay precision and accuracy, and the lower limit of quantification, linearity, stability and matrix effects; with all results meeting acceptance criteria. The method was used successfully in a pilot pharmacokinetic study with patients with peritoneal dialysis-associated peritonitis, receiving either intraperitoneal cefazolin or cefalothin. This article is protected by copyright. All rights reserved.
Article
The present research study describes the use of response surface methodology by Box–Behnken design in optimization and validation of the new microwell-based UV-Visible spectrophotometric method for determination of CEF in its formulation. The absorbance of the colored-charge transfer (CT) complex was measured at 460 nm by microwell-plate absorbance reader. Under the optimum conditions, linear relationship with good correlation coefficient (0.999) was found between the absorbance and the concentration of CEF in the range of 10-100 μg/well. The limits of detection and quantitation were 2.06 and 6.85 μg/well, respectively. The relative standard deviations did not exceed 4.03% for the intra- and inter- assay precisions The assay was successfully applied to the analysis of CEF in its pharmaceutical dosage forms with good accuracy and precision. The assay described herein has great practical value in the routine analysis of CEF in quality control laboratories, as it has high throughput property, consumes minimum volume of organic solvent thus it offers the reduction in the exposures of the analysts to the toxic effects of organic solvents. This multivariate approach enables substantial improvement in the method development using fewer experiments, without wastage of large volumes of organic solvents, which leads to high analysis cost. © 2015, Latin American Journal of Pharmacy. All rights reserved.
Article
A spectrophotometric study concerning the charge transfer reaction of 1,4,8,11-tetraazacyclotetradecane (CYCLAM) and π-acceptor, 2,2-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been performed in chloroform solution at 25°C. The results are indicative of the formation of CYCLAM-DDQ and CYCLAM +-DDQ - through equilibrium and non-equilibrium steps, respectively. The formation constant of the equilibrium step has been evaluated by the computer fitting of absorbance-mole ratio data as log K f = 5.5 ± 0.2. The plotting In (A t/A 0) vs. time has obtained the rate constant of non-equilibrium step. The obtained k value is equal to 0.011 ± 0.001 min -1. Solid complex of CYCLAM-DDQ has been isolated and the IR spectrum of the complex has been compared with the spectra of donor and acceptor.
Article
Charge-transfer (CT) complexes formed between perylene (Pery) as donor with iodine (I 2), piciric acid (PA) and chloranilic acid (CLA) as acceptors were studied spectrophotometrically. The synthesis and characterization of perylene CT complexes of iodine, [(Pery) 2]I +.I3 I -, picric acid, [(Pery)(PA)] and chloranilic acid, [(Pery)(CLA)] were described. These complexes were readily prepared by the reaction of Pery with I 2, PA and CLA using CHCl 3 as a solvent. The IR, UV-Vis and 1HNMR spectral techniques, as well as elemental analysis (carbon, hydrogen and nitrogen contents) and thermal analysis were used to characterize the three perylene charge-transfer complexes. Benesi-Hildebrand method and its modification were applied to the determination of association constant (K) and molar absorption coefficient (e). © 2012 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.
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The purpose of this investigation was directed to propose sensitive, accurate and reproducible methods of analysis that can be applied to determine distigmine bromide (DTB), cyclopentolate hydrochloride (CPHC), diaveridine hydrochloride (DVHC) and tetrahydrozoline hydrochloride (THHC) drugs in pure form and pharmaceutical preparations via charge-transfer complex formation with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE) reagents. Spectrophotometric method involve the addition a known excess of TCNQ or TCNE reagents to DTB, CPHC, DVHC and THHC drugs in acetonitrile, followed by the measurement of the absorbance of the CT complexes at the selected wavelength. The reaction stoichiometry is found to be 1:1 [drug]: [TCNQ or TCNE]. The absorbance is found to increase linearly with concentration of the drugs under investigation which is corroborated by the correlation coefficients of 0.9954-0.9981. The system obeys Beer's law for 6-400, 20-500, 1-180 and 60-560 µg mL(-1) and 80-600, 10-300, 1-60 and 80-640 µg mL(-1) for DTB, CPHC, DVHC and THHC drugs using TCNQ and TCNE reagents, respectively. The apparent molar absorptivity, sandell sensitivity, the limits of detection and quantification are also reported for the spectrophotometric method. Intra- and inter-day precision and accuracy of the method were evaluated as per ICH guidelines. The method was successfully applied to the assay of DTB, CPHC, DVHC and THHC drugs in formulations and the results were compared with those of a reference method by applying Student's t and F-tests. No interference was observed from common pharmaceutical excipients.
Article
A novel potentiometric sensor was prepared, characterized and utilized for static and continuous determination of cefazolin sodium (CFZN). Several metalion complexes and anion exchangers were tested as electroactive materials in plasticized polymeric membranes for selective detection of CFZN. Among different electroactive species tridodecyl methyl ammonium chloride (TDMAC) doped membrane electrode was found to exhibit optimal response characteristics. The optimized membrane sensor exhibited near-Nernstian responses (-55.64 mV decade-1) over CFZN concentration range of 0.41-10 mM as measured in 50 mM acetate buffer, pH 5.5. The proposed sensor offers the advantage selectivity, does not require pre-treatment and possible interfacing with computerized and automated systems. It is worth noting that the developed membrane electrode exhibited good selectivity toward CFZN over other cephalosporins such as; cefradine, ceftazidime, cefadroxil, cefaclor and cefoperazone, as well as some additives encountered in the pharmaceutical preparations and so these sensors were successfully used for determination of CFZN. A tubular-type detector incorporating a TDMAC based membrane sensor was prepared and used under hydrodynamic mode of operation for continuous CFZN quantification. The tubular-type detector exhibited a concentration range from 0.5-10 mM with a near-Nernstian response (-53.91 mV decade-1). Continuous monitoring of CFZN offers the advantages of simple design, ease of construction and possible applications to small volumes of drug solutions without pre-treatment. The developed sensor was utilized successfully in static and continuous modes of operation for the determination of CFZN in dosage forms. The results obtained were in good agreement with the standard method of CFZN analysis.
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This paper describes two simple, sensitive and selective spectrophotometric and atomic absorption spectrometric (AAS) procedures for the determination of two compounds of cephalosporins (Cephalexin monohydrate and Cephradine). These procedures are based on the formation of ion-pair complexes between the drugs and ammonium reineckate. The formed precipitates are quantitatively determined either spectrophotometrically or by AAS procedures. The methods consist of reacting drugs with Reinecke's salt in an acidic medium at a temperature of 25 ± 2°C. The spectrophotometric procedure (procedure I) is based on dissolving the formed precipitate with acetone. The volume was completed quantitatively and absorbance of the solution was measured at 525 nm against blank. Also, the AAS procedures (procedure II) are quantitatively determined directly or indirectly through the chromium precipitate formed or the residual unreacted chromium in the filtrate at 358.6 nm. The optimum conditions for precipitation have been carefully studied. Beer's law is observed for the studied drugs in the ranges 0.1-1.5 mg mL-1 or 5-70 μg mL-1 using spectrophotometric or AAS methods, with correlation coefficients ≥ 0.9965, respectively. Both procedures I and II were accurate and precise when applied to the analysis of the cited cephalosporins in different dosage forms with good recovery percent ranged from 98.90 ± 0.94 to 100.15 ± 0.97 without interference from additives.
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A novel chemiluminescence (CL) system for the determination of cefazolin sodium is developed based on the direct chemiluminescence reaction of [Ag(HIO 6) 2] 5-Rhodamine 6G (Rh6G)-cefazolin sodium system in sulphuric acid medium. The possible mechanism of chemiluminescence emission and enhancing effect was discussed. Rhodamine 6G can be oxidized by Ag(III) complex to be its excited form (Rh6G *), which could produce chemiluminescence emission at about 550 nm. Otherwise, Rhodamine 6G can be oxidized by Ag(III) complex to be Rh6G oxide. Cefazolin sodium in acid solution could be oxidized by Ag(III) complex to be its excited form, which could excite Rh6G oxide to be its excited form (Rh6G oxide *), which could produce chemiluminescence emission at about 420 nm. The regression equations of the calibration curves in the range of 4.0 × 10 -8-4.0 × 10 -6 g/mL can be shown as follows: LgI = 0.0018 C + 1.9848, with a correlation coefficient (R 2) of 0.9902. The limit of detection (LOD) was 1.73 × 10 -8 g/mL. The proposed method was applied satisfactorily for the determination of cefazolin sodium in the injectable powder and patient urine.
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The charge transfer interaction between the donor p-nitroaniline with the acceptor chloranilic acid has been studied spectrophotometrically in various solvents such as chloroform, ethanol, and methanol at room temperature. The results indicate that formation of CTC in non-polar solvent is high. The stoichiometry of the complex was found to be 1:1 ratio by straight-line method between donor and acceptor with maximum absorption bands. The data are discussed in terms of formation constant (KCT), molar extinction coefficient (εCT), standard free energy (ΔG), oscillator strength (f), transition dipole moment (μN), resonance energy (RN) and ionization potential (ID). The results indicate that the formation constant (KCT) for the complex was shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents that were used. The formation of the complex has been confirmed by UV-visible, FT-IR, and 1H–NMR techniques.
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The charge-transfer (CT) complex formed between piperidine (Pip) as donor and iodine (I2) ) as σ-acceptor was studied spectrophotometrically. The synthesis and characterization of the piperidine CT-complex of iodine, [(Pip) 2]I +.I 3-, was described. This complex was readily prepared by the reaction of Pip with I 2 in CHCl 3 solvent. Infrared spectra (mid-IR and far-IR), UV-Vis techniques and elemental analyses were used to characterize the piperidine/I 2 charge-transfer complex. Benesi-Hildebrand's method and its modifications were applied to the determination of the association constant (K) and the molar absorption coefficient (ε). © 2011 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.
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New procedure for preparation of glycine and alanine triiodide charge transfer complexes by solid-solid interactions were investigated using different spectroscopic tools. The triiodide charge transfer complexes were prepared by grinding of potassium iodide, iodine and amino acid with 1:1:1 M ratio in the presence of few drops of methanol solvent. The formulas of two solid amino acid charge transfer complexes were discussed using the infrared, Raman laser, UV–Vis. and electronic spectra, and thermal analyses. The structural changes of both complexes were probed using the positron annihilation lifetime (PAL) and positron annihilation Doppler broadening (PADB) techniques. The results reveal that most of PAL and PADB parameters are strongly correlated with the molecular weight of the prepared CT complexes.
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Two simple and sensitive visible spectrophotometric methods M 1 and M 2 are described for the assay of galantamine hydrobromide in pure and solid dosage forms. The method M1 is based on the formation of coordination complex between drug (electron donor) and CTC, colored species is formed and exhibits absorption maxima at 610nm. The method M2 is based on ion association complex formation of Tpooo with drug and exhibits absorption maxima at 500nm. Regression analysis of Beer's-lambert plots showed good correlation in the concentration ranges(0.5-3.0ml, 100µg/ml) for the method M1,(1.0-5.0Ml,500µg/mL) for the method M2 respectively. The proposed methods are applied to commercial available tablets and the results are statically compared with these obtained by the UV reference method and validated by recovery studies. The results are found satisfactory and reproducible. These methods are applied successfully for the estimation of the galantamine hydrobromide in the presence of other ingredients that are usually present in dosage forms. These methods offer the advantages of rapidity, simplicity and sensitivity and normal cost can be easily applied to resource-poor settings without the need for expensive instrumentation and reagents.
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Amoxicillin, ampicillin, cefalexin and cefadroxil are the most extensively used beta-lactam antibiotics due to their broad spectrum of action and low cost. The quality of the pharmaceutical formulations of these drugs being marketed needs to be ensured to achieve a better remedial effect and a lower toxicity. The widespread exploitation of antibiotics sometimes leads to their presence in residues in body fluids and water bodies, which is potentially toxic and dangerous for human health. Thus, the determination of these drug compounds in pharmaceutical formulations, biological fluids and in water samples is of great importance and scope. Owing to the inherent ease and simplicity and sensitivity of spectrophotometric methods, the reactions of above drug compounds with carbon disulphide and copper(I) perchlorate in the presence of pyridine to form acrylonitrile extractable yellow coloured copper(I) drug dithiocarbamate complexes has been investigated for the spectrophotometric determination of these drugs. The analysis is accomplished by measuring the intensity of yellow extract at 450, 378, 380 and 430 nm for amoxicillin, ampicillin, cefalexin and cefadroxil respectively against a reagent blank. Under the optimized condition calibration graphs were linear in the ranges of 1.68-167.78, 1.61-161.38, 1.39-138.96 and 1.45-145.36 μg/mL with the detection limit (3.3 σ / s) of 1.24, 1.19, 1.07 and 1.13 μg/mL respectively. The high recoveries of the listed drugs by the proposed method from respective pharmaceutical formulations (98.80-100.30 %), simulated biological fluids (98.46-100.21 %) and spiked water samples (98.32-99.66 %) with RSDs in the ranges 0.15-1.11 % indicate good accuracy and precision of the method.
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We developed a reversed-phase high-performance liquid chromatography method with ultraviolet detection using on-line complexation with Cu(II) ion for analysis of five alcohols including diols and triol (methanol, ethanol, 1,2-propanediol, 1,3-propanediol, and glycerol). The Cu(II) ion concentration in the mobile phase had a great influence on the peak areas of these alcohols, but not on their retention times. Column temperature (25 − 40°C) and pH of the mobile phase did not affect the separation of analytes. The optimum separation conditions were determined as 5 mM CuSO4, 3 mM H2SO4, and 3 mM NaOH at 30°C. The ratio of the peak areas for three alcohols (methanol, 1,2-propanediol, and glycerol) was in good agreement with that calculated from the obtained stability constants, molar absorption coefficients for the 1:1 Cu(II) complexes with the three alcohols, and the injected molar quantities. This fact strongly suggests that the observed high-performance liquid chromatography signals resulted from formation of the 1:1 Cu(II)–alcohol complexes. Using the proposed method, these five alcohols in spirit, liquid for electronic cigarette, mouthwash, and nail enamel remover samples were successfully analyzed with only a simple pretreatment. This article is protected by copyright. All rights reserved
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Bacterial resistance to antibiotics is a growing phenomenon in world. Considering the relevance of antimicrobials for population and the reduction in the registration of new antimicrobials by regulatory, proper quality control is required in order to minimize the spread of bacterial resistance and ensure the effectiveness of a treatment, as well as safety for patient. Among the antimicrobials is cefotaxime, a drug belonging to third-generation cephalosporins – that is highly active against Gram-negative bactéria and is used to treat central nervous system infections such as meningitis and septicemia. Due to the critical importance of quality control in regard to drugs and pharmaceutical products, combined with bacterial resistance to antibiotics, this study aims to conduct a detailed review of analytical methods for cefotaxime. Using a critical review of literature, this paper describes the analytical methods published to quantify cefotaxime in different matrices; a large number of methods by HPLC and spectrophotometry was observed. Despite the advantages of the techniques, most methods reported have large environment and occupational impact, which enfatizes the need to adopt green procedures in quantifying cefotaxime.
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A new microextraction approach termed forced vortex assisted liquid phase microextraction (FVA-LPME) has been developed and optimized for spectrophotometric determination of mefenamic acid (MFA) as a model compound. FVA-LPME is based on the formation of a rotational vortex of organic phase within aqueous phase and subsequent partition of target analyte between two phases. Rotation of fine layer of organic phase as a solid body within aqueous phase accelerates the mass transfer and improves the extraction efficiency. MFA is extracted into organic phase by FVA-LPME procedure and subsequently derivaitized by iodine to form a charge transfer complex for spectrophotometric detection. A response surface methodology (RSM) based on central composite chemometrics design was used for multivariate optimization of the effects of three different parameters influencing the extraction efficiency. Under the optimal conditions, the calibration curve was linear in the range of 10–900 ng mL⁻¹ of MFA with a R² of 0.998. The repeatability and reproducibility (RSD%) for 200 ng mL⁻¹ MFA were 2.6% and 3.3%, respectively and limit of detection limit (S/N = 3) was estimated to be 3.1 ng mL⁻¹. The results demonstrated that the developed method is an accurate, inexpensive, rapid and reliable sample pretreatment method that gives very good enrichment factor and detection limit for extracting and determining MFA in biological samples.
Article
Polymeric sheets of poly(methyl methacrylate) (PMMA) doped by charge-transfer (CT) complex of perylene/iodine (pyr/I2), perylene/picric acid (pyr/PA) and perylene/chloranilic acid (pyr/CLA) were synthesized in methanol solvent at room temperature. The optical spectroscopic studies on PMMA polymer doped by charge transfer complex are determined by UV–Vis–NIR spectroscopy, Photoluminescence spectroscopy (PL), Vis–NIR diffused reflectance spectroscopy (DRS) and FTIR spectroscopy. The diffused reflectance spectroscopy (DRS) of the polymeric sheet samples is analyzed based on the Kubelka–Munk model. The indirect allowed optical band gaps of the polymeric sheet samples are estimated by applying absorption spectrum fitting (ASF) and Tauc's methods. Here we report the optical spectroscopic studies on PMMA polymer doped by charge transfer complex as potential materials to be used in optoelectronic devices.
Article
Objective: To evaluate a validated, simple, sensitive, inexpensive, green method for determination of cefoperazone Na and cefepime hydrochloridein pure form, pharmaceutical dosage form and human urine using ferric chloride and ferricyanide by spectrophotometry. Method: The estimation is based on the reduction of ferric ions in its salt form to ferrous ions by the drug, which in presence of potassium ferricyanide produces greenish blue colored chromogen measured at 766 nm against blank. The proposed method was applied to the determination of these drugs in pharmaceutical formulations and urine. Results: Beer's law was obeyed in the concentration range 0. 8-8 μg/mL, for both drugs, the limits of detection and quantificationwere reported. The intensity of the color in case ofcefoperazone Na increases with time at room temperature and so a kinetic method was developed for its determination. The results demonstrate that the method is equally accurate and precise as the reference methods as found from the t- and F-values. The reliability of the method was established by recovery studies using standard-addition technique. Conclusion: The proposed method has higher sensitivity than many of the reported methods, the method is green analytical methods so, it is inexpensive and ecofriendly. Moreover, the method doesn't require various elaborate treatments and tedious extraction procedures.
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An accurate, sensitive and simple spectrophotometric method has been developed and validated for determination of cefadroxil (CFX) in bulk and pharmaceutical formulations. The method is based on the oxidation of 2,4-dinitrophenylhydrazine (DNP) using potassium periodate (PPI) to produce a diazonium salt which is coupled with CFX to form a colored chromogen which was measured at 515 nm. Appropriate conditions were examined for the reaction to obtain maximum absorptivity and sensitivity. The optimum conditions were 1.5 mL of 0.1% 2,4-DNP, 1.5 mL of 0.15% PPI and 0.5 mL of 10 M NaOH solution at room temperature. The method was linear in a concentration range between 7.5-75 µg/mL with regression coefficient of 0.998 (n=5). The limit of detection (LOD) and limit of quantification (LOQ) were 0.89 and 2.7 µg/ml, res .3 ± (0.28 – 0.14). The developed method was applied successfully for determination of CFX in capsules, tablets and suspension, therefore, it could be used for routine analysis of the drug in pharmaceutical dosage forms.
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Cephalexin, cefixime, ceftriaxone and cefotaxime were determined spectrophotometrically in the pure form and in pharmaceutical formulations by using ferrihydroxamate method. Reaction optimization with respect to reaction time and temperature has been investigated. Influence of the presence of ester functional group on the determination of cephalosporins as ß-lactams under conditions optimized was evaluated. Using cefotaxime sodiume as model drug with ester functional group, it was shown that proposed method gives equally acurate and precise results even in the presence of ester functional group.
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CONTENTS I. Introduction 408 II. Nature of charge-transfer complexes 408 III. Donors 409 IV. Acceptors 410 V. Methods of investigating charge-transfer complexes and some of their properties 411 VI. Charge-transfer complexes and the mechanism of chemical reactions 414
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Two simple, rapid and selective spectrophotometric procedures were developed for the determination of amoxicillin and cefadroxil. The methods are based on the selective oxidation of the drugs with N-bromosuccinimide or N-chlorosuccinimide in an alkaline medium to give an intense yellow product (λmax= 395 nm). The reaction conditions were studied and optimized. The reactions obey Beer's law over the range 1–20 µg ml–1 for the two drugs with the two reagents. Interferences from other antibiotics, additives and common degradation products were investigated. The proposed methods were applied to the analysis of pharmaceutical formulations containing amoxicillin, either alone or in combination with potassium clavulanate or flucloxacillin. They were also applied to the analysis of some cefadroxil dosage forms. The results obtained compared favourably with those obtained with other reported methods.
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A rapid, sensitive and selective method is described for the determination of some penicillin derivatives and their additive and degradation products in the presence of each other. Penicillin derivatives are separated from their degradation and additive products on high performance thin layer silica gel G plates. The plates were developed in a linear chamber, air dried, exposed to iodine vapour and measured on a spectrodensitometer at 290 nm. Procaine and procaine penicillin are measured at 360 nm. The results of the analysis show good agreement with the method of the USP XXI. For the reaction of penicillins with iodine, the formation of charge-transfer complexes is considered.
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Benzylpenicillin, benzathine benzylpenicillin, procaine benzylpenicillin, anhydrous ampicillin and sodium ampicillin form charge-transfer complexes with iodine in 1,2-dichloroethane, which were examined by UV, FIR, 1H-NMR, 13C-NMR, and 15N-NMR spectroscopy. Bildung von Charge-Transfer Komplexen von Penicillinen mit Iod. Benzylpenicillin, Benzylpenicillin-Benzathin, Benzylpenicillin-Procain, wasserfreies Ampicillin und Ampicillin-Natrium bilden nach UV-, FIR-, 1H-NMR-, 13C-NMR- und 15N-NMR-Untersuchungen mit Iod in 1,2-Dichlorethan Charge-Transfer Komplexe.
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The interaction of alkaloids with selected polyhaloquinone and polycyanoquinone π-acceptors was found to yield intensely coloured radical ions. This finding was developed into a sensitive spectrophotometric assay for alkaloids of general applicability and with adequate accuracy and precision. 7,7,8,8-Tetracyanoquinodimethane is used as the reagent. Anwendung von π-Acceptoren zur quantitativen Analyse von Alkaloiden Alkaloide geben mit π-Acceptoren vom Typ der Polyhalogenchinone und Polycyanochinone intensiv gefärbte Radikal-Anionen. Auf Grund dieser Reaktion wurde eine allgemein anwendbare, empfindliche photometrische Bestimmungsmethode für Alkaloide entwickelt, die auf der Umsetzung mit 7,7,8,8-Tetracyanochinondimethan beruht.
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Two rapid and simple spectrophotometric methods as well as a selective and sensitive spectrodensitometric procedure are described for the determination of cephalothin sodium (CT) and cephradine (CD). The spectrophotometric methods are based on the charge-transfer complex formation between these derivatives as n-donors and iodine, the o-acceptor or 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ, π-acceptor). The obtained charge-transfer complex with iodine shows two maxima at 295 and 365 nm in 1.2-dichloroethane while it shows a single maximum at 460 nm wih DDQ in methanol. Beer's law is obeyed in a concentration range of 2–30 and 2–16 μg/ml with iodine; 10–120 and 30–270 μg/ml with DDQ for CT and CD respectively. In the spectrodensitometric method, cephalosporin derivatives are separated from their degradation or additive products on high performance thin-layer silica gel G plates. The plates were then developed, air dried, exposed to iodine vapour and measured on a spectrodensitometer at 290 and 360 nm for CD and CT respectively. The proposed methods are successfully applied to the analysis of CT and CD dosage forms.
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A rapid and convenient spectrophotometric method is described for the quantitative determination of some of Cephalosporines Cefadroxil, I Cephradine II and Cefaclor III. The proposed method depends upon the conversion of these compounds to the corresponding piperazine-2,5 dione derivatives by heating in an alkaline sorbitol-zinc ion solution for 10—25 minutes at 90°C and subsequent treatment of these derivatives with 0.1 N sodium hydroxide to obtain highly absorbing products with λmax at 345 nm for I & II and at 334 nm for III using zero order absorption curve. Using first derivative spectrum (D1) for III the λmax is at 362 nm. The method was found to be free of the interference from polymerization and other degradation products. Its application to assess the stability of the Cephalosporines was demonstrated. Verification of Beer's Law showed lincarity at concentrations of 12.5-87.5 μg ml−1, 12.5-125 μg ml−l and 6.7-66.7 μg ml−1 for I, II and III respectively with mean accuracies 100.37 ± 0.72%, 100.45 ± 0.87% and 99.63 ± 1.97% when using zero order absorption curve. Using D1 for III gave linearity at concentration range 42-114 μg.ml−1 with mean accuracy of 99.54 ± 0.77%.
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Two spectrophotometric methods for the determination of cefadroxil using Cu(II) and V(V) in sulphuric acid medium are described. Beer's law is obeyed up to 100 μg ml−1 and the molar absorptivities are 2.10 × 103 and 3.81 × 103 L mol−1 cm−1 with copper and vanadium respectively. The two methods have been applied successfully to the analysis of the pharmaceutical preparations (Duricef oral suspension and capsules).
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A simple, rapid and sensitive Spectrophotometric method is proposed for the determination of cephadroxil (I), cephalexin (II) and cephradine (III). The method is based on ion-pair complex formation between these derivatives and Chromotrope 2B (C2B) or Chromotrope 2R (C2R), to give a highly coloured radical anion. The coloured products are quantified spectrophotometrically at 542 and 564 nm for C2B and C2R, respectively. The optimization of the experimental conditions is described. The method has been used for the determination of 0.4–15, 0.4–14 and 0.4–18 g/ml of drugs I, II and III, respectively. The accuracy of the method is indicated by the excellent recovery (100.01.7%) and the precision is supported by the low relative standard deviations 1.5%. The sensitivity of the method is discussed and the results are compared with the official method. The interference from common degradation products and excipients was also studied. The proposed method was applied successfully to the determination of the different cephalosporins in dosage forms, with good precision and accuracy. The results were compared with those given by the official B.P. 1993 method.
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Three simple and sensitive visible spectrophotometric methods for the assay of cefadroxil have been developed. MethodA (max 410 nm) is based on the reaction of cefadroxil with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the presence of eeric ammonium sulphate. MethodB (max, 510 nm) involves the reaction with 4-aminophenazone in the presence of potassium hexacyanoferrate(III). MethodC (max, 620 nm) involves reaction with 2, 6-dichloroquinone-4-chlorimide (Gibb's reagent). All variables have been optimised and the reaction mechanisms presented. Regression analysis of the Beer's plots showed good correlation in the concentration ranges 1.0–6.0, 2.0–24.0 and 1.0–6.0 g/ml for methodsA, B andC, respectively. No interferences were observed from excipients and the validity of the methods was tested by analysing pharmaceutical dosage forms. Recoveries were 98.0–100.3%. The concentration measurements were reproducible within a relative standard deviation of 1.0%.
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Rev. ed. of: Vogel's textbook of quantitative inorganic analysis. 4th. ed. 1978 Incluye bibliografía e índice
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A colorimetric method for the determination of five cephalosporins (cefoxitin sodium, cefotaxime sodium, cephapirin sodium, cephalothin sodium and cephaloridine), based on the blue colour formed by reaction of the cephalosporins with ammonium molybdate, is described. The effects of reagent concentration and reaction conditions are discussed. The proposed method has been applied to the analysis of cephalosporin injections, the results of which are in good agreement with those obtained by the official method of the British Pharmacopoeia.
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A spectrophotometric method for the determination of some tetracyclines as well as some cephalosporins is described. The drug is boiled with ammonium vanadate solution in sulphuric acid medium for 10 min and the absorbance of the colour developed is measured at 750 nm. The proposed method can be successfully applied to the determination of tetracycline hydrochloride, oxytetracycline hydrochloride, doxycycline hyclate, demeclocycline hydrochloride, chlortetracycline hydrochloride, cephalothin sodium, cephaloridine and cephapirin sodium. These drugs can be determined either in pure form or in pharmaceutical preparations.
Article
Two simple and sensitive spectrophotometric methods are described for the determination of six penicillin derivatives. The methods are based on the reaction of these drugs as n-electron donors with either 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) as pi-acceptors, to give a highly coloured radical anion. The coloured products are quantified spectrophotometrically at 460 and 842 nm for DDQ and TCNQ, respectively. The optimization of the different experimental conditions is described. The interference from streptomycin sulphate and common degradation products was also studied. The proposed methods were applied successfully to the determination of the different penicillins investigated, either in pure or dosage forms, with good accuracy and precision. The results were compared with those given by the official United States Pharmacopeial XXI method.
Article
The use of molybdophosphoric acid as an oxidising agent for the spectrophotometric determination of four cephalosporin derivatives, viz., cefadroxil monohydrate (I), cefapirin sodium (II), ceforanide L-lysine (III) and cefuroxime sodium (IV), either in the pure form or in pharmaceutical formulations is described. Beer's law is obeyed up to 100 micrograms ml-1 for I, up to 60 micrograms ml-1 for II and IV and up to 80 micrograms ml-1 for III. The molar absorptivities were 4.58 X 10(3), 11.3 X 10(3), 9.8 X 10(3) and 10.9 X 10(3) l mol-1 cm-1 and the Sandell sensitivities were 83.3, 39.3, 53.0 and 41.0 ng cm-2 for I, II, III and IV, respectively. The slopes and intercepts of the equations of the regression line were calculated for each of these drugs with the following correlation coefficients: I, 0.9993; II, 0.9999; III, 1.000; and IV, 0.9999. These antibiotics were determined successfully both in the pure form and in pharmaceutical preparations. The results demonstrated that the proposed procedure is at least as accurate, precise and reproducible as the official methods, while being simpler and less time consuming. A statistical analysis indicated that there was no significant difference between the results obtained by the proposed procedure and those of the official methods.
Article
Cephalosporins and penicillins give reproducible yields of ammonia on degradation in 0.5 M sodium hydroxide solution at 100 degrees C: the ammonia formed was determined in the degraded solutions using the indophenol reaction. In another approach the ammonia driven off on refluxing alkaline solutions of the cephalosporin or penicillin was collected in dilute hydrochloric acid solution and determined using the indophenol reaction. For eight of the fourteen cephalosporins and penicillins studied identical yields were recorded using the two procedures: these varied from 29% for penicillin G to 137% for cephalonium based on the production of one ammonia molecule per beta-lactam molecule. For six other cephalosporins the distillation method gave substantially higher yields of ammonia than did the direct determination. Eight cephalosporins and penicillins were found to give substantial indophenol-type reactions without prior hydrolysis of the beta-lactam, but the sensitivities were usually lower than for the hydrolysis method. Manual spectrophotometric procedures for the determination of cephalosporins and penicillins based on these reactions have been developed.
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