Ghodratollah Absalan

Shiraz University, Chimaz, Fārs, Iran

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Publications (42)106.1 Total impact

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    ABSTRACT: A carbon ionic liquid electrode modified with Fe3O4 magnetic nanoparticle (Fe3O4NPs/CILE) was employed for nitrite determination by cyclic voltammetry. The results showed that the Fe3O4NPs/CILE exhibited a significant improvement in the oxidation peak current of nitrite. After optimizing the operational conditions, a linear response range from 10 to 900 µmol L−1 with a low detection limit of 0.70 µmol L−1 was obtained. The proposed sensor was stable with a sensitivity of 0.0402 μA μmol−1 L and good repeatability evaluated in terms of relative standard deviation (RSD n = 6). Possible interferences from several coexisting ions were evaluated. The sensor was applied for voltammetric determination of nitrite in some real samples. The results were consistent with those obtained with the standard spectrophotometric procedure.
    Journal of the Iranian Chemical Society 07/2015; 12(7). DOI:10.1007/s13738-015-0594-z · 1.41 Impact Factor
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    ABSTRACT: A novel kinetic spectrophotometric method is developed for determination of ampicillin. The method is based on aggregation of gold nanoparticles in a chemical process that involved decomposition of ampicillin catalyzed by cadmium ion in methanol as solvent. The optimum experimental conditions for determination of ampicillin were established. The method permitted determination of ampicillin in a concentration range of 16.0–96.0 µg ml−1 with a detection limit of 13.0 µg ml−1. The interferences of the species which are mostly available in biological samples were not significant in determination of ampicillin. The method is simple and sensitive for analyzing of ampicillin and is applicable for its assay in pharmaceutical formulations.
    Journal of the Iranian Chemical Society 05/2015; 12(5). DOI:10.1007/s13738-014-0551-2 · 1.41 Impact Factor
  • Morteza Akhond, Ghodratollah Absalan, Hamid Ershadifar
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    ABSTRACT: A novel, simple and highly sensitive colorimetric method is developed for determination of Amoxicillin (AMX). The system is based on aggregation of citrate-capped gold nanoparticles (AuNP) in acetate buffer (pH=4.5) in the presence of the degradation product of Amoxicillin (DPAMX). It was found that the color of gold nanoparticles changed from red to purple and the intensity of surface plasmon resonance (SPR) peak of AuNPs decreased. A new absorption band was appeared in the wavelength range of 600-700nm upon addition of DPAMX. The absorbance ratio at the wavelength of 660 and 525nm (A660/A525) was chosen as the analytical signal indirectly related to AMX concentration. The linearity of the calibration graph was found over the concentration range of 0.3-4.5μM AMX with a correlation coefficient of 0.9967. Under the optimum experimental conditions, the detection limit was found to be 0.15μM. The applicability of the method was successfully demonstrated by analysis of AMX in pharmaceutical formulations including capsules and oral suspensions. Copyright © 2015 Elsevier B.V. All rights reserved.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 02/2015; 143C:223-229. DOI:10.1016/j.saa.2015.01.071 · 2.13 Impact Factor
  • Ghodratollah Absalan, Morteza Akhond, Hamid Ershadifar
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    ABSTRACT: A new application of a carbon ionic liquid electrode (CILE) has been explored for preconcentration and quantification of trace amount of Au(III) chlorocomplexes. The procedure is based on the accumulation of tetrachloroaurate complexes at the electrode surface under an open circuit potential condition followed by cyclic voltammetry (CV) and differential pulse cathodic stripping voltammetry (DPCSV). An ion exchange mechanism has been proposed for efficient and fast accumulation of Au(III) chlorocomplexes. Effects of different experimental parameters such as electrolyte concentration, pH, and preconcentration time on the voltammetric signals were investigated. It was found that under the optimized experimental conditions, the linear range of measurement and the detection limit were 5.00 × 10−9–2.25 × 10−6 and 0.80 × 10−9 mol L−1, respectively. Possible interference from coexisting ions was also studied. The procedure was applied for determination of gold in water and human blood serum samples, and acceptable accuracy was achieved.
    Journal of Solid State Electrochemistry 01/2015; 19(4). DOI:10.1007/s10008-014-2720-8 · 2.23 Impact Factor
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    Maryam Ghaemi, Ghodratollah Absalan, Leila Sheikhian
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    ABSTRACT: This paper assesses the adsorption characteristics of Titan yellow and Congo red on CoFe2O4 magnetic nanoparticles. The adsorption behavior of Titan yellow and Congo red from aqueous solution onto CoFe2O4 magnetic nanoparticles has been determined by investigating the effects of pH, concentration of the dye, amount of adsorbent, contact time, ionic strength and temperature. Experimental results indicated that CoFe2O4 nanoparticles can remove more than 98 % of each dye under optimum operational conditions of a dosage of 15.0 mg CoFe2O4, pH 3.0, initial dye concentration of 22–140 mg L−1, and contact times of 2.0 and 15.0 min for Congo red and Titan yellow, respectively. Langmuir and Freundlich isotherm models have been used to evaluate the ongoing adsorption kinetic equations. Regeneration of the saturated adsorbent was possible by NaCl/acetone solution as eluent. The maximum adsorption capacities were 200.0 and 212.8 mg dye per gram adsorbent for Congo red and Titan yellow, respectively. With the help of adsorption isotherm, thermodynamic parameters such as free energy, enthalpy and entropy have been calculated. On the basis of pseudo-first-order and pseudo-second-order kinetic equations, different kinetic parameters have been obtained.
    Journal of the Iranian Chemical Society 12/2014; 11(6). DOI:10.1007/s13738-014-0448-0 · 1.41 Impact Factor
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    ABSTRACT: Nystatin, one of the tetraene antifungal antibiotics, is very sensitive to light. Thus, when nystatin is exposed to natural daylight, it is photodegraded to products of lower biological activity. In this work, the photodegradation kinetics of nystatin was monitored by a UV-Vis spectrophotometry method. The absorbance spectra of the nystatin, exposed to a 366 nm UV lamp, were recorded at different periods of time. By application of factor analysis to the absorbance data matrix, three absorbing chemical species, coexisting in the reaction system, were detected. The soft-modeling multivariate curve resolution-alternating least squares analysis of the evolutionary absorbance data revealed that nystatin undergoes photodegradation in a two-step consecutive manner. Hard-modeling data analysis suggested that reaction has first-order kinetics in the first step and zero-order kinetics in the second step. The reaction rate constants of the first and second steps were estimated as 0.0929 (±0.0076) and 0.0052 (±0.0016)/min, respectively. Finally, the pure spectra of the resolved chemical species were calculated.
    Journal of AOAC International 08/2014; 97(4). DOI:10.5740/jaoacint.13-110 · 1.39 Impact Factor
  • Shokoufeh Ahmadi, Ghodratollah Absalan, Douglas Craig, Douglas Goltz
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    ABSTRACT: Purpurin is an anthraquinone dye that is found in plant material such as Madder root. The separation of purpurin using capillary electrophoresis under alkaline condition can be complicated by reproducibility in peak height and peak shape. In this study the poor peak reproducibility of capillary electrophoresis separations was attributed to photochemical properties of purpurin. Experiments were carried out using UV visible and fluorescence spectrophotometry to measure the 1st order rate constant for the photochemical fading of purpurin. At pH = 9.24 the rate constant was 4.5 x 10(-3) s(-1) and at pH = 7.0 the rate constant was determined to be 5.0 x 10(-5) s(-1). Proton NMR, thin layer chromatography, gas chromatography and UV visible spectrophotometry techniques were also employed to identify the photo-degraded products of purpurin. (c) 2014 Elsevier Ltd. All rights reserved.
    Dyes and Pigments 06/2014; 105:57–62. DOI:10.1016/j.dyepig.2013.12.011 · 3.47 Impact Factor
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    Maryam Ghaemi, Ghodratollah Absalan
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    ABSTRACT: We have investigated the adsorption of herring sperm DNA on Fe3O4 magnetic nanoparticles (NPs) before and after modification with the ionic liquid 1-hexyl-3-methylimidazolium bromide. Experiments were performed in a batch mode, and the effects of DNA concentration, pH of the sample solution, ionic strength, temperature, and contact time between reagents were optimized. An evaluation of the adsorption isotherm revealed that the Langmuir model better fits the equilibrium data than the Freundlich model. The maximum adsorption capacities of the unmodified and modified NPs, respectively, were found to be 11.8 and 19.8 mg DNA per gram of adsorbent. The adsorption of DNA onto the modified NPs was endothermic, while it was exothermic in the case of the unmodified NPs. The DNA can be desorbed from the modified surfaces of the NPs by using EDTA as the eluent. The NPs were able to adsorb about 90 ± 1.5 % of DNA after being recycled for three times. The method is simple, fast, robust, and does not require organic solvents or sophisticated equipment. FigureFe3O4 nanoparticles as well as 1-hexyl-3-methylimidazolium bromidecoated Fe3O4 nanoparticles were prepared and used for adsorption of DNA. The mean size and the surface morphology of both nanoparticles were characterized by TEM, DLS, XRD, FTIR and TGA techniques. The correlation coefficient of the Langmuir model suggests a better fit for the experimental equilibrium adsorption data.
    Microchimica Acta 01/2014; 181(1-2). DOI:10.1007/s00604-013-1040-5 · 3.72 Impact Factor
  • Maryam Ghaemi, Ghodratollah Absalan
    Journal of the Iranian Chemical Society 01/2014; 12(1):1-7. DOI:10.1007/s13738-014-0450-6 · 1.41 Impact Factor
  • Sedigheh Kamran, Mozaffar Asadi, Ghodratollah Absalan
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    ABSTRACT: In this paper, nanoparticles of Fe3O4 as well as its binary mixtures with ionic liquid 1-hexyl-3-methylimidazolium bromide (IL-Fe3O4) were prepared and used for adsorption of folic acid, riboflavin and ascorbic acid. The mean size and the surface morphology of both nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy techniques. The pH of the point of zero charge (pHpzc) of both Fe3O4 and IL-Fe3O4 were obtained based on the experimental curves corresponding to the immersion technique. Experimental results were obtained under the optimum operational conditions of: 40 mg of nanoparticle and contact time of 10 minutes with an initial concentration of the vitamins of 20 mg L−1. The isotherm evaluations revealed that the Freundlich model attained better fits to the equilibrium data than the Dubinin-Radushkevich model. The maximum obtained adsorption capacities of folic acid, riboflavin and ascorbic acid were 22.5, 4.8 and 6.9 mg per gram of adsorbent, respectively. The adsorption capacities of the vitamins were found to be dependent on their chemical structures, pH of the solution and temperature. The applicability of pseudo-first order and pseudo-second order kinetic models was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. Furthermore, both adsorption processes of folic acid and ascorbic acid were endothermic and vitamins could be desorbed from IL-Fe3O4 nanoparticles by using NaCl solution at pH 3.0 for recycling the nanoparticles.
    Analytical methods 01/2014; 6(3):798. DOI:10.1039/c3ay41543k · 1.94 Impact Factor
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    ABSTRACT: The partitioning behavior of model acidic (bovine serum albumin, BSA), basic (hen egg white lysozyme, LYS), and neutral (horse heart myoglobin, MYO) proteins in ionic liquid-based aqueous biphasic systems containing Reactive Red-120 dye has been reported. This study found that partition coefficients of the proteins depended on their chemical structures, pH of the aqueous phase, temperature, and composition of the aqueous biphasic system. It was found that partition coefficients of proteins in aqueous biphasic system containing RR-120 were in the order of LYS > MYO > BSA. Recovery of the hydrophilic ionic liquid, [C4mim]Br, was achieved by using hydrophobic ionic liquid, [C4mim]PF6.
    Separation Science and Technology 10/2013; 48(15). DOI:10.1080/01496395.2013.804086 · 1.20 Impact Factor
  • Ghodratollah Absalan, Yousef Alipour
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    ABSTRACT: A novel methodology for analysis of enantiomer composition of chiral compounds based on measuring of their critical micelle concentration by using spectrophotometric technique is introduced. The proposed method does not require any chiral selector and the corresponding process is simple, fast, reproducible, and inexpensive. The procedure was successfully applied for analysis of naproxen. The critical micelle concentration data showed that (R)-naproxen could be determined with an RSD of 1.1% and a relative error of -5.6% when a real sample containing the racemic mixture of naproxen with a total concentration of 0.04mM was tested.
    Journal of pharmaceutical and biomedical analysis 04/2013; 83C:96-100. DOI:10.1016/j.jpba.2013.04.034 · 2.83 Impact Factor
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    ABSTRACT: An extracellular protease was purified from a novel moderately halophilic bacterium Salinivibrio sp. strain MS-7 by the combination of an acetone precipitation (40-80 %) step and a DEAE-cellulose anion exchange column chromatography. Kinetic parameters of the enzyme exhibited V max and K m of 130 U/mg and 1.14 mg/ml, respectively, using casein as a substrate. The biochemical properties of the enzyme revealed that the 21-kDa protease had a temperature and pH optimum of 50 °C and 8.0, respectively. The enzyme was strongly inhibited by phenylmethylsulfonyl fluoride, Pefabloc SC, chymostatin, and also EDTA, indicating that it belongs to the class of serine metalloproteases. Interestingly, Ba(2+) and Ca(2+) (2 mM) strongly enhanced the enzyme activity, while Fe(2+) and Mg(2+) activated moderately and Zn(2+), Ni(2+), and Hg(2+) decreased the enzyme activity. The effect of organic solvents with different logP on the purified protease revealed complete stability in toluene, ethyl acetate, chloroform, and n-hexane at 10 and 50 % (v/v) and moderate stability even in 50 % of DMSO and ethanol. The behavior of the MS-7 protease in three imidazolium-based ionic liquids exhibited suitable activity in these green solvent systems, especially in 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]). Comparison of the purified protease with other previously reported proteases suggests that strain MS-7 secrets a novel organic solvent-tolerant protease with outstanding activity in organic solvents and imidazolium-based ionic liquids, which could be applied in low water synthetic section of industrial biotechnology.
    Applied biochemistry and biotechnology 04/2013; DOI:10.1007/s12010-013-0215-1 · 1.69 Impact Factor
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    L. Sheikhian, M. Akhond, G. Absalan
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    ABSTRACT: In this paper partitioning behaviors of reactive red-120, 4-(2-pyridylazo)-resorcinol, and methyl orange as model azo dyes in ionic liquid-based aqueous biphasic systems were studied. For designing aqueous biphasic systems and investigating the partitioning of the model dyes, phase diagrams and binodal curves were obtained at 25 °C for [C4mim][Br]/salt systems at different pH values. It was found that the partition coefficients of the studied dyes depended on their chemical structures, pH of the aqueous phase, temperature and composition of the aqueous biphasic system. Ionic liquid-based aqueous biphasic extraction was an efficient and suitable method for partitioning of dyes into ionic liquid-rich top phase. Efficient extraction of dyes into IL phase was done within 1 min. The hydrophilic ionic liquid 1-butyl-3-methylimidazolium bromide, [C4mim][Br], in top phase was efficiently recovered by using the hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6]. In the recycling process, almost no dye was extracted into [C4mim][PF6] phase.
    Journal of Environmental Chemical Engineering 01/2013; DOI:10.1016/j.jece.2013.12.005
  • M. Asadi, G. Absalan, A. Zamanpour
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    ABSTRACT: New complexes of Co(II), Ni(II), Cu(II) and Zn(II) with four new tetraaza Schiff base ligands, N,N′-bis(2-quinolylmethylidene)-1,2-ethanediimino (L1), N,N′-bis(2-quinolylmethylidene)-1,2-propanediimino (L2), N,N′-bis(2-quinolylmethylidene)-1,3-propanediimino (L3), N,N′-bis(2-quinolylmethylidene)-4-nitro-1,2-phenylenediimine (L4), were synthesized and characterized by elemental analysis, IR, 1H NMR, and UV-Vis spectroscopy. The thermodynamic formation constants of the complexes were measured spectrophotometrically, at the constant ionic strength 0.1 M (NaClO4), at 25 °C in MeOH solvent. The trend of the complex formation of a given metal ion with the ligands was found to be as follows L2 > L1 > L3 > L4 and the trend of a given ligand with the metal ions was Co(II) > Ni(II) > Cu(II) > Zn(II).
    Journal of the Iranian Chemical Society 12/2012; 8(4). DOI:10.1007/BF03246565 · 1.41 Impact Factor
  • Ghodratollah Absalan, Yousef Alipour, Zahra Rezaei, Morteza Akhond
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    ABSTRACT: Many chiral selectors have been used for recognition of enantiomeric compounds but their synthesis involves time-consuming and expensive multistep-processes with almost not optically pure products. In this paper, 1-butyl-3-methylimidazolium (T-4)-bis[(αS)-α-(hydroxy-O) benzeneacetato-κO] borate, a chiral ionic liquid which can be easily synthesized, was first used as a chiral selector in solution. The enantiomer compositions of propranolol hydrochloride were determined by using this chiral selector and the spectrophotometric method. The data of UV spectra showed that S-propranolol hydrochloride could be recognized in the mixture of the enantiomers with a total concentration of 1.50 × 10−4 M.
    Analytical methods 07/2012; 4(8):2283-2287. DOI:10.1039/C2AY25161B · 1.94 Impact Factor
  • Ghodratollah Absalan, Maryam Ghaemi
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    ABSTRACT: In this paper, adsorption behaviors of typical neutral (alanine), acidic (glutamic acid) and basic (lysine) amino acids onto the surfaces of neutral as well as positively and negatively charged silver chloride nanoparticles were examined. Silver chloride nanoparticles with different charges and different water content were synthesized by reverse micelle method. The adsorptions of the above mentioned amino acids onto the surfaces of differently charged silver chloride nanoparticles were found to depend strongly on various parameters including pH of the aqueous solution, type of amino acid, water to surfactant mole ratio, and type of charges on the surfaces of silver chloride nanoparticles. It was found that the interaction of -NH(3) (+) groups of the amino acids with silver ion could be a driving force for adsorption of amino acids. Alanine and Glutamic acid showed almost similar trend for being adsorbed on the surface of silver chloride nanoparticles. Electrostatic interaction, hydrophobicity of both nanoparticle and amino acid, complex formation between amine group and silver ion, interaction between protonated amine and silver ion as well as the number of nanoparticles per unit volume of solution were considered for interpreting the observed results.
    Amino Acids 04/2012; 43(5):1955-67. DOI:10.1007/s00726-012-1270-6 · 3.65 Impact Factor
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    ABSTRACT: In water, methylene blue (MB) is known to be aggregated to dimmer and trimmer at high concentration levels. We conducted a thermodynamic study on the aggregation of MB using multivariate curve resolution analysis of the visible absorbance spectra over a concentration range of 2.0 × 10-6−4.0 × 10-4 M. A hard modeling-based multivariate curve resolution method was applied to determine the dissociation constants of the MB aggregates at various temperatures ranging from 25 to 75 °C. This method was able to resolve the visible absorbance spectra as a function of MB concentration in individual temperature or simultaneously in all other temperature ranges. Utilizing the van’t Hoff relation, the enthalpy and entropy of the dissociation equilibriums were calculated. For the dissociation of both aggregates, the enthalpy and entropy changes were positive and negative, respectively.
    Journal of the Iranian Chemical Society 03/2012; 8(1). DOI:10.1007/BF03246213 · 1.41 Impact Factor
  • Sedigheh Kamran, Mozaffar Asadi, Ghodratollah Absalan
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    ABSTRACT: We have prepared and characterized Fe3O4 nanoparticles and their binary mixtures (IL-Fe3O4) with 1-hexyl-3-methylimidazolium bromide as ionic liquid for use in the adsorption of lysozyme (LYS), bovine serum albumin (BSA), and myoglobin (MYO). The optimum operational conditions for the adsorption of proteins (at 0.05–2.0 mg mL−1) were 4.0 mg mL−1 of nanoparticles and a contact time of 10 min. The maximum adsorption capacities are 455, 182 and 143 mg for LYS, BSA, and MYO per gram of adsorbent, respectively. The Langmuir model better fits the adsorption isotherms, with adsorption constants of 0.003, 0.015 and 0.008 L mg−1, in order, for LYS, BSA, MYO. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. The adsorption processes are endothermic. The proteins can be desorbed from the nanoparticles by using NaCl solution at pH 9.5, and the nanoparticles thus can be recycled. Figure Nanoparticles of Fe3O4 as well as its binary mixtures with ionic liquids (IL-Fe3O4) were prepared and used for adsorption of lysozyme, bovine serum albumin and myoglobin. The mean size and the surface morphology of both nanoparticles were characterized by TEM, DLS, XRD, FTIR and TGA techniques. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients
    Microchimica Acta 01/2012; 180(1-2). DOI:10.1007/s00604-012-0901-7 · 3.72 Impact Factor
  • Ghodratollah Absalan, Maryam Arabi, Javad Tashkhourian
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    ABSTRACT: An optode was designed for an indirect determination of ascorbic acid by using neocuproine, which has been coated on transparent triacetylcellulose film as a membrane. The proposed method is based on the oxidation of ascorbic acid to dehydroascorbic acid with the Cu(II) and neocuproine reagent. The increase in the absorbance value of the optode at the maximum wavelength of 455 nm was related to the ascorbic acid concentration in aqueous samples. The sensitivity of the method was improved by using room-temperature ionic liquid, [C(8)MIM][PF(6)]. The linear dynamic range for the determination of ascorbic acid was 7.4 × 10(-5) - 3.5 × 10(-3) mol L(-1) with a limit of detection of 2.2 × 10(-5) mol L(-1) (n = 10) and a response time range of 6.0 - 8.0 min. The optode was successfully applied for the determination of ascorbic acid in orange juice.
    Analytical Sciences 01/2012; 28(12):1225-30. DOI:10.2116/analsci.28.1225 · 1.40 Impact Factor