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Spectrophotometric determination of hydrogen peroxide using tris(1,10-phenanthroline)iron(II)
Abstract
Hydrogen peroxide reacts with iron(II) in acidic medium, and the unreacted iron(II) forms a stable complex with 1,10-phenanthroline that absorbs at 508 nm. This indirect spectrophotometric method, based on the absorbance reduction of tris(1,10-phenanthroline)iron(II) was utilised for the determination of hydrogen peroxide. The effective molar absorptivity for H2O2 is 2.22 × 104 l mol–1 cm–1. The proposed procedure is sensitive and has been applied to the analysis of commercial peroxide samples. Possible interferences are discussed.
... This concept has been exploited for determination of H 2 O 2 in the samples. 12,13 Herein, we took advantage of this assay further in a way that after adding ferrous ion, the scavenger is added and followed by known amount of H 2 O 2 for few minutes. If the scavenger is capable enough to scavenge the H 2 O 2 added in the sample, no ferrous to ferric conversion would occur and detected by addition of 1,10-phenanthroline which ...
... Although it has been shown earlier that the Fe +2 : 1,10-phenanthroline ratio should be at least 1:6 or more for optimum complexation, [11] but in a recent paper it is proved that even 1:4 ratio between Fe +2 and 1,10-phenanthroline could be sufficient enough to form complex which can give strong absorbance at 510 nm. 12 To resolve the issue, we took a range of Fe +2 : 1,10-phenanthroline from 16:1 to 2:1 by volume (using 1 mM each of Fe +2 salt and 1,10-phenanthroline) and checked for the ratio where optimum complexation i.e. maximum absorbance could be observed. ...
... Additionally, we have determined the optimum ratio between ferrous ammonium sulphate and 1,10-phenanthroline as there is conflicting data regarding the ratio between this two reagents. 11,12 Our result showed that the optimum ratio between ferrous ammonium sulphate and 1,10-phenanthroline was 1:6 ( Figure 2b). ...
Introduction: Hydrogen peroxide (H 2 O 2) is a biologically important, non-radical reactive oxygen species (ROS) that can influence several cellular processes. Ability of anti-oxidants to scavenge H 2 O 2 can be measured by several methods but all the methods are suffering from several lacunae due to poor reproducibility, lack of specificity, inaccuracy, high cost etc. Objective: The present study aimed towards development of a rapid, low cost, reproducible, specific as well as sensitive and accurate method to detect H 2 O 2 scavenging activity of anti-oxidants. Methods: We have used 1,10-phenanthroline and ferrous ammonium sulphate to detect H 2 O 2 scavenging activity of anti-oxidants. Results: We revealed that our assay is able to detect the in vitro H 2 O 2 scavenging activity of both phenolic and non-phenolic anti-oxidants. Furthermore, we found that this assay is highly specific, as scavengers of other types of ROS were unable to show any detectable effect on H 2 O 2 through this assay. Finally, we tested commercially available non-steroidal anti-inflammatory drugs that are known to possess H 2 O 2 scavenging activity and in such drugs also we were able to detect their H 2 O 2 scavenging activity. Conclusion: In conclusion, the proposed spectrophotometric method was rapid, cost effective, reproducible and highly specific to detect in vitro H 2 O 2 scavenging activity of diverse compounds.
... The assay was used to measure the degree of lipid peroxidation in a lipid-rich substrate; MDA is a secondary product of lipid peroxidation [26]. We used the TBARS formation technique during the oxidation of linolenic acid, instead of linoleic acid, is based on the fact that MDA (TBARS) would be formed only from fatty acids comprising at least three double bonds [1]. According to the results obtained by production of substances reacting with thiobarbituric acid test, essential oil of Halopitys incurvus seaweed shows significant antioxidant activity by value of IC50 of 100±0,91μg/ml (Fig. 4). ...
... Большое внимание уделяется инструментальным методам анализа: хроматографическим [2][3][4] и электрохимическим [5][6][7]. Широкое распространение получила и спектрофотометрия [8][9][10]. В настоящее время разработано значительное количество спектрофотометрических методик определения пероксида водорода, в том числе и твердофазных, с использованием ферментов [11,12] и наночастиц металлов [13][14][15][16], для экспрессного его определения используют тест-методы [10,[17][18][19]. ...
... Determination of hydrogen peroxide is usually based on the production of colored peroxy compounds or on its oxidizing and reducing properties. For the sensitive determination of hydrogen peroxide chemiluminescence [l,2], spectrophotometic [3][4][5][6], and spectrofluorimetic [7][8][9][10], continuous-flow analysis [11], flow injection [12], and kinetic methods [13] have also been reported. ...
A Spectrofluorometric method for microdetermination of H2O2 has been developed. The method is based on the oxidation of hydrogen peroxide with ceric ion in acid solution and measurement of the fluorescence during titration of the Ce(III) ions produced. The fluorescent species have excitation and emission maxima at 260 and 360 nm, respectively. The detection limit of measurement by this method was 0.1 ppm hydrogen peroxide.
Hydrogen peroxide (H2O2) is widely used in the synthesis of organic chemicals, bleaching of paper pulp, and the treatment of wastewater and as a food additive, important mediator of redox processes in natural water, and a disinfectant. However, H2O2 stock solution is unstable and slowly decomposes when exposed to, for example, light, elevated temperatures, or metal compounds. Therefore, the ability to measure the exact concentration of H2O2 stock solution is important for its proper use in diverse applications. This work proposes a simple method for the spectrophotometric determination of H2O2 solution via chemical reaction with sodium hypochlorite that is inexpensive and easy to acquire. The proposed method is based on the stoichiometric spectral change of hypochlorite ion at 292.5 nm following a redox reaction with a sample solution of H2O2. Due to high relationship between the spectral delta value and the applied H2O2 concentration (0.00188-0.03000%), H2O2 stock solution can be easily quantified.
Fouling remains one of the key challenges in membrane technology. In pressure-driven membrane separations, the vibrational energy induced by hydraulic pumps often dissipates unexploited. We present an innovative concept, in which the hydraulic pressure vibration is converted to electrical energy in the outlet of a filtration pump through an embedded piezoelectric nanogenerator (PENG) ceramic. We found that by increasing the average pressure of the hydraulic pump, the dynamic pressure fluctuation increased. The maximum output voltage of 219.6 V was obtained at 20 psi average pressure. The generated piezoelectricity was directly applied to an electro-assisted membrane cell in either alternating mode or positive/negative rectified form to mitigate membrane fouling. In the first configuration, ultrafiltration (UF) membrane was placed between two metallic electrodes. The optimum fouling resistance was achieved when the positive rectified piezoelectric pole was connected to the electrode. Water flux decline (FD) and water flux recovery ratio (FRR) were improved by 28.6% and 52.1%, respectively, compared to the case where no voltage was applied. In the second configuration, a piece of water-permeable and electro-conductive carbon nanotube (CNT) mat was mounted over the UF membrane and it was connected to the piezoelectric wafer using a wire. The alternating piezoelectricity provided the best antifouling performance in this configuration, with FD of 32.5% and FRR of 78.3%. The generated piezoelectricity was also used as a power source to drive an electro-Fenton (EF) reaction coupled with nanofiltration (NF) for reactive black 5 (RB5) dye separation. The results showed that the highest RB5 degradation rate (8.8%) was achieved when the rectified negative and positive poles were connected to the graphite paper and stainless-steel mesh electrodes, respectively. The proposed piezoelectric energy harvesting can revolutionize the traditional methods of fouling reduction in the electro-membrane processes where an external power should be applied for the oxidation reactions to occur.
New molecule α-aminophosphonate namely (2-hydroxynaphthalen-1-yl) methyl 2-hydroxyphenyl amino phosphonic acid (HMHP) was synthesized by condensation based on 2-amino phenol and 2-hydroxy naphthaldehyde. During the reaction, imine intermediate namely 2-hydroxyphenyl imino naphthalen-2-ol (HIN) was formed before adding acid phosphorous to the reaction mixture. It can be confirmed the concept of Kabachinik-Fields reaction, which it's perform the attachment of phosphorus atom to the carbon atom of imine function. Both compounds were identified using IR, ¹H, ¹³C and ³¹P NMR spectroscopic techniques. The evaluation of the antioxidant activity of HMHP and HIN was investigated by utilizing several in vitro assays: scavenging activity against DPPH radical and H2O2 non radical, β-carotene/linoleic acid against linoleic peroxidation, reducing power against ferric oxidation and phosphomolybdate (TAC) against molybdate ion oxidation. Results indicate that HMHP reflects greater antioxidant potency compared to HIN in most tests, where it is apt to offer the hydrogen radical very well at IC50 (37.64 ± 1.43) in DPPH test. For the other tests the inhibition percent at 50 % are relatively closed between them. Except the H2O2 scavenging, while HIN exhibited excellent activity at IC50 (24.7306 ± 0.71785). The quantum chemical calculations were performed using density functional theory (DFT) to study the effects of the transfer electronic and proton transfer on the antioxidant activities of the synthesized compounds. Also, theoretical FT-IR was calculated. The experimental results are in comfort with those calculated theoretically.
Spectroscopic data of standard additions were collected and used to calculate the spectrum of the unknown interferent(s) based on the net analyte signal. The proposed method was named net analyte signal interferent modelling (NAS-IM). In the next step, an H-point standard addition method was used to obtain the concentration of the analyte in the sample. The method was applied to determine hydrogen sulfide and hydrogen peroxide in urine and milk samples, respectively. The results of the method were validated by analysis of the second-order data of the same samples by multivariate curve resolution-alternating least squares (MCR-ALS) and parallel factor analysis (PARAFAC). The concentration of the analytes calculated by NAS-IM and second-order methods has a maximum difference of 7.7%.
Hydrogen peroxide (HP) has undergone somewhat of a rebirth in chemical industry circles over the last decade. The rather glib explanation for such a renaissance is that regulatory forces compelled the chemical industry to reduce, and in some instances to eliminate, environmental pollution. Since industry has learned to employ HP in a safer, more efficient and innovative manner, it can substitute many environmentally hazardous chemicals in an environmentally protective way. The most important applications of HP in industrial processes are summarized in Fig. 1 [1–4].
In order to purify a lignin-degrading enzyme from the bacterium Azotobacter beijerinckii HM121, which rapidly decolorizes lignin, the enzyme activity was monitored by observing the hydroquinone oxidizing activity in the presence of hydrogen peroxide. The activity was bound to the membrane and was solubilized by treating disrupted cells with 0.1% Triton X-100. The enzyme was purified to homogeneity by ammonium sulfate fractionation, hydrophobic chromatography on butyl-Toyopearl 650M, and gel filtration on Toyopearl HW-55F. The relative molecular mass of the enzyme was determined to be 59,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis and 55,000 by gel filtration on Toyopearl HW-55F, suggesting it is a monomeric enzyme. The purified enzyme exhibited the maximal activity for hydroquinone oxidation at pH 7.0 and 50°C and was stable up to 70°C for 1 h. The optimum concentration of hydrogen peroxide was 6.0 mM. The enzyme was active toward hydroquinone, vanillin, catechol, caffeic acid, p-phenylenediamine, pyrogallol, methylhydroquinone, and dimethylhydroquinone. Based on these results the enzyme was named hydroquinone peroxidase. The enzyme also decolorized and degraded lignin. Spectral analysis revealed that this peroxidase did not have iron-heme. Inductively coupled plasma analysis showed the presence of equimolar manganese. The enzyme activity was inhibited by 1 mM EDTA and by 1 mM 1,10-phenanthroline; the activity of the EDTA-inactivated enzyme was restored by the addition of manganese ions. However, the enzyme activity did not require exogenous manganese ions and was not promoted by the addition of manganese. The peroxidase oxidized Mn(II) to Mn(III) in the presence of hydrogen peroxide. The activity was promoted 4 fold by the addition of 0.1 mM ZnCl2. The enzyme formed a hydroxy radical from hydrogen peroxide as an active oxygen molecule. From the above results, the hydroquinone peroxidase was judged to be a new type of lignin-degrading enzyme.
Delayed chemiluminescence (CL) was observed in the copper(II)-catalyzed oxidation of cysteamine with oxygen in the presence of horseradish peroxidase (H RP) and luminol. After preferential catalytic oxidation of cysteamine by both Cu(II) and HRP, a HRP-catalyzed luminol CL reaction was subsequently commenced with hydrogen peroxide accumulated from the catalytic oxidation. Thus, a delay time from the reaction initiation to a sharp flash of CL was observed. The HRP-catalyzed CL-delay of luminol was applied to the determination of Cu(II). The delay time was linearly correlated with the Cu(II) concentration over the range from the detection limit of 5.0X 10(-9) to 1.5X10(-5) M. The detection limit of the present method is a factor of 30 times better than that of the conventional luminol CL method. The relative standard deviation of the delay time in five successive experiments was 3.2% at 1.0X10(-7) M of Cu(II). The present method was highly sensitive compared to the conventional luminol CL method.
The ternary titanium(IV), vanadium(V) and molybdenum(VI) complexes with H2O2 and 5-Br-PADAP were investigated by spectrophotometry (Vis) and chromatography (LC). Occurrence of two different ternary titanium(IV) complexes with hydrogen peroxide and 5-Br-PADAP (limited by concentration of methanol in the sample) was established. Stability of Ti(IV) and V(V) ternary complexes under spectrophotometric and chromatographic conditions was discussed. Two liquid chromatographic methods for the determination of hydrogen peroxide based on the Ti(IV) and V(V) ternary complexes were developed. Calibration curves are linear within wide ranges of hydrogen peroxide concentration: 0.02–5.00 and 0.15–5.00μmoll−1 with detection limits 0.016 and 0.150μmoll−1 for vanadium(V) and titanium(IV) systems, respectively. The method based on vanadium(V) system was used for the determination of H2O2 traces in rainwater, generated in water subjected to sonication and on the surface of the plant leaf (Plantago lanceolata L.), as well as for indirect determination of glucose in a human serum.
Hydrogen peroxide formed during the course of the copper(II)-catalysed oxidation of cysteamine with oxygen was continuously determined by a peroxidase (POD)-catalysed luminol chemiluminescence (CL) method. Horseradish peroxidase (HRP), lactoperoxidase (LPO) and Arthromyces ramosus peroxidase (ARP) were used as a CL catalyst. The respective PODs gave specific CL intensity-time profiles. HRP caused a CL delay, and ARP gave a time-response curve which followed the production rate of H2O2. LPO gave only a weak CL flash which decayed promptly. These differences of CL response curves could be explained in terms of the different reactivities of PODs for superoxide anion and the different formation rate of luminol radicals in the peroxidation of luminol catalysed by POD.
A method for the indirect spectrophotometric determination of H2O2 is based on its oxidation with chlorine in basic medium and measurement of the unreacted Cl2 by the colour reaction with o-tolidine at 438 nm. The effective molar absorptivity for H2O2 with o-tolidine is 5.37104 mol–1 cm–1 at pH 1.7. The lower limit of determination is 1.8510–7 mol/l or 6.29 ppb. Br–, I–, NO–
2, Pb2+ and Sn2+ interfere even in small amounts, but are not present in commercial H2O2.
A luminol chemiluminescence (CL) method was developed for the determination of glutathione (GSH). GSH was indirectly determined by measuring the amount of hydrogen peroxide formed during the Cu(II)-catalysed oxidation of GSH with oxygen. The amount of hydrogen peroxide formed was continuously measured using the Arthromyces ramosus peroxidase-catalysed luminol CL reaction. The CL intensities at maximum light emission were linearly correlated with the concentration of GSH over the range 7.5 x 10(-7)-3.0 x 10(-5) M. The detection limit for GSH was about 10 times better than that of the spectrophotometric method using Ellman reagent.
An electrochemical optical sensor system with luminescence response was proposed for the continuous determination of hydrogen peroxide or peroxydisulphate concentration in aqueous solutions. The electroluminescence (EL) of TiO(2) film electrodes, which arises under conditions of the cathodic polarization as a result of the hole injection into the TiO(2) from high-energy OH or SO(4)(2-) radicals produced by the electroreduction of H(2)O(2) or S(2)O(8)(2-) ions on the electrode surface, was used as the analytical signal. The EL response is linearly related, in a logarithmic scale, to the hydrogen peroxide or peroxydisulphate concentration ranging from 10(-3) to 10(-1) M H(2)O(2) and from 5 x 10(-4) to 1 M Na(2)S(2)O(8). It was shown that a substantial increase in the quantum efficiency of the EL and, as a consequence, in the sensitivity of the sensor system can be achieved by doping TiO(2) films with chromium. The potential dependence of the EL spectrum for TiO(2) electrodes in S(2)O(8)(2-) solutions differs essentially from that in H(2)O(2) solutions which allows measurement of the concentration of S(2)O(8)(2-) ions when they coexist with H(2)O(2) in solution.
A simple and sensitive method for the determination of nanomolar levels of hydrogen peroxide (H(2)O(2)) in seawater has been developed and validated. This method is based on the reduction of H(2)O(2) by ferrous iron in acid solution to yield hydroxyl radical (OH) which reacts with benzene to produce phenol. Phenol is separated from the reaction mixture by reversed phase high performance liquid chromatography and its fluorescence intensity signals were measured at excitation and emission of 270 and 298nm, respectively. Under optimum conditions, the calibration curve exhibited linearity in the range of (0-50)x10(3)nmolL(-1) H(2)O(2). The relative standard deviations for five replicate measurements of 500 and 50nmolL(-1) H(2)O(2) are 1.9 and 2.4%, respectively. The detection limit for H(2)O(2), defined as three times the standard deviation of the lowest standard solution (5nmolL(-1) H(2)O(2)) in seawater is 4nmolL(-1). Interference of nitrite ion (NO(2)(-)) on the fluorescence intensity of phenol was also investigated. The result indicated that the addition of 10micromolL(-1) NO(2)(-) to seawater samples showed no significant interference, although, the addition of 50micromolL(-1) NO(2)(-) to the seawater samples decreases the fluorescence intensity signals of phenol by almost 40%. Intercomparison of this method with well-accepted (p-hydroxyphenyl) acetic acid (POHPAA)-FIA method shows excellent agreement. The proposed method has been applied on-board analysis of H(2)O(2) in Seto Inland seawater samples.
A kinetic flow-injection (FI) method is described for the determination of hydrogen peroxide. This method is based on an iron(III)-catalyzed oxidative coupling of 4-aminoantipyrine with N,N-dimethylaniline by hydrogen peroxide. By measuring the change in the absorbance of the dye formed at 560 nm, 1 x 10(-6) - 6 x 10(-4) M hydrogen peroxide could be determined with a sampling rate of 15 h(-1). The relative standard deviation (n = 30) was 0.8% for 5 x 10(-5) M hydrogen peroxide. There was little interference of the co-existing ions and compounds. After introducing some immobilized enzyme reactors to the FI system, the proposed method allowed the determination of glucose and uric acid ranging from 1 x 10(-6) to 6 x 10(-4) M with relative standard deviations of below 2%. The applicability of the method was demonstrated by determining these substances in serum samples.
We describe a simple colorimetric method for determining micromolar quantities of hydrogen peroxide, based on the oxidation of iodide in the presence of ammonium molybdate and photometry of the resulting blue starch-iodine complex. Color development is linearly dependent on analyte concentration, but only slightly time dependent, and the color of the complex formed is stable for several hours. In the range of wavelengths that may be used (570 to 630 nm), lack of interference from other biological compounds makes this method seem suitable for routine analyses. As one illustrative application of the method we quantitated glucose by measuring hydrogen peroxide produced from it by glucose oxidase catalysis. This method of quantitating glucose is more than five times as sensitive as the commonly used dianisidine method. With the appropriate hydrogen peroxide-producing oxidases, this method may be used to directly measure amino acids, purines, uric acid, xanthine, and hypoxanthine.
In an attempt to develop a practically useful mimesis of peroxidase, the peroxidase-like catalytic activity of anion exchange resins (Amberlite IRA 900) modified with manganese, cobalt, iron, copper and zinc complexes of some porphyrins was examined in terms of the accelerating effect on dye formation in the following reaction. The evaluation of the activity was carried out by comparison of the effect obtained by using the resins with that obtained by using peroxidase.4-aminoantipyrine +N, N-diethylaniline + 2H2O2peroxidase→quinoid dye + 4H2OAmberlite IRA 900 modified with manganese-tetrakis (sulfophenyl) porphine was found to be the best among the resins tested.
Five procedures are presented for the determination of hydrogen peroxide and organic hydroperoxides (including organic peroxyacids) at concentrations of 1–10 μM in aqueous soltion. All five are spectrophotometric methods, based on formation of phenolphthalein or triiodide, catalytic dye bleaching, coupled oxidation of NADPH, and horseradish peroxidase-coupled oxidations. Each is evaluated in terms of sensitivity, selectivity and reliability. The method based on coupled oxidation of NADPH is the most widely applicable to peroxidic species, whereas the horseradish peroxidase method can be made highly selective for hydrogen peroxide.
Two spectrophotometric methods for the trace determination of hydroperoxides in benzene-methanol medium are compared. The first is based on complex formation between FeII and 1, 10-phenanthroline (tentatively denoted by FeIIP), and the other makes use of the complex formed between FeIII and the thiocyanate anion (tentatively denoted by FeIIIT). The thiocyanate method, when modified by adding more benzene to the system and employing active silver to suppress the blank values, proved to be less laborious, more sensitive and faster than the determination with 1,10-phenanthroline. The yield of FeIIIT is almost stoicheiometric, which is not so for the FeIIP complex. Owing to its simplicity, great sensitivity and reproducibility, the modified thiocyanate method is suitable for series determinations.
In medium of pH=1, vanadium(V) forms a 1 ∶ 1 cationic complex with PAR, the instability constant of the complex beingpK=5.6. In the presence of hydrogen peroxide a 1∶1∶1 mixed-complex develops which is uncharged. The molar absorptivity of the complex (ɛ
540=1.28×104 l·mole−1·cm−1) provides a possibility for the spectrophotometric determination of 1–65μM hydrogen peroxide.
The formation of mixed ligand complexes in Ti(IV)-xylenol orange (XO)-H2O2 and Ti(IV)-chromazurol S (CAS)-H2O2 systems was studied by spectrophotometry. The former system gave constant absorbance (λmax = 562 nm) under the condition of [XO]/[Ti(IV)] = 1 in the pH 2-4 region. In the latter system, a distinct maximum at 557 nm was observed when [CAS]/[Ti(IV)] = 4 in the pH range of 4.5-5.2. In both cases, the absorbance at λmax was stable for a long time and proportional to the concentration of hydrogen peroxide. From those facts, the usefulness of the mixtures of Ti(IV)-XO and Ti(IV)-CAS as the colorimetric reagents for the determination of hydrogen peroxide can be expected. The conditions for the use of the Ti(IV)-XO and the Ti(IV)-CAS reagents were examined in detail, and both reagents were found to be available for trace analysis of hydrogen peroxide with high sensitivity.
Vanadium(V) forms 2:1, 1:1, and 1:2 binary complexes with xylenol orange (XO). In slightly alkaline solution the formation of the complexes is almost instantaneous, whereas it takes a day for the equilibria to be reached at pH 4. On the action of hydrogen peroxide, both the 2:1 and the 1:1 complexes are transformed into mixed-ligand complexes, with 2:1:2 and 1:1:1 compositions, respectively. No intramolecular redox reaction takes place between XO and hydrogen peroxide. Peroxo complex formation can be used for estimation of hydrogen peroxide if the decrease in absorbance of the 576-nm band of the binary complexes is measured. The molar absorptivity decrease depends on the ratio and the pH.
A method of analysis of hydrogen peroxide in concentrations of about 10−1M, applicable to solutions which are stable towards alkaline hexacyanoferrate(III) and hexacyanoferrate(II), is suggested. The hydrogen peroxide is determined spectrophotometrically at 418 mμ from the decrease in absorbance it causes in a 1 × 10−1M potassium hexacyanoferrate(III) in 0·1 M potassium hydroxide.ZusammenfassungEine Methode zur Bestimmung von Wasserstoff-peroxyd in Konzentrationen von etwa 10−4m wird vorgeschlagen. Sie 1äßt sich auf Lösungen anwenden, die gegen alkalisches Hexacyanoferrat(III) und -(II) stabil sind. Das Wasserstoffperoxyd wird spekralphotometrisch bei 418 mμ bestimmt an Hand der Extinktionsabnahme, die es an einer 1·10−2m Kaliumhexacyanoferrat(III)-Lösung in 0,1m Kaliumhydroxyd hervorruft.RésuméOn propose une méthode de dosage de l'eau oxygénée à des concentrations d'environ 10−4M, applicable aux solutions qui sont stables vis-à-vis des hexacyanoferrate(III) et hexacyanoferrate(II) alcalins. L'eau oxygénée est dosée spectrophotométriquement à 418 mμ, par la diminution d'absorbance qu'elle apporte à une solution 1 × 10−1M d'hexacyanoferrate(III) de potassium en potasse 0,1 M.
A reagent-injection flow technique, which allows automatic control of the volume of reagent to be injected, is described. The sensitivity of the measurements can be adjusted over a wide range by changing the injection volume. This technique also eliminates problems in photometric determinations arising from refractive index effects and from light scattering by suspended particles in the sample. Consequently, absorbances as small as 0.00004 can be measured. The capabilities of this reagent-injection flow technique were tested by using it to determine hydrogen peroxide in seawater at nanomolar levels with photometric detection. The concentration of hydrogen peroxide was determined as the colored condensation product of N-ethyl-N-(sulfopropyl)aniline and 4-aminoantipyrene; the detection limit was 12 nM.
A sensitive procedure is described for trace analysis of hydrogen peroxide in water. The procedure involves the peroxidase‐catalyzed oxidation of the leuco forms of two dyes, crystal violet and malachite green. The sensitivity of this procedure, as well as of another procedure based on the peroxidase‐catalyzed oxidation of p‐hydroxyphenylacetic acid (POHPA), is decreased in natural water samples and in aqueous solutions of aquatic humic substances. This decrease, which is less pronounced with the POHPA method, may be caused by competititve reactions of peroxidase intermediates with phenolic components of the humic substances. (This work was performed as part of an environmental exchange agreement between the United States and the Soviet Union).
Hydrogen peroxide reacts with the colored benzohydroxamic acid chelates of vanadium(V) and uranium(VI) to destroy the chelate and form the metal peroxide complex. The decrease in color of the benzohydroxamic acid chelate is a measure of the amount of peroxide present. It is possible to detect 7 X 10 -6 mole of hydrogen peroxide using the uranium chelate (pH 6 and 380 mμ) and 1 X 10 -6 mole using the vanadium system (pH 3 and 450 mμ). By using a 1-hexanol extraction the color due to the metal peroxide complexes formed does not interfere. Hydroperoxides and dialkyl peroxides do not interfere appreciably at the pH's required for this determination.
A differential spectrophotometric method for the determination of traces of hydrogen peroxide is based on the decrease in absorbance due to the iron(II) phenanthroline complex in the presence of hydrogen peroxide. 1,10-Phenanthroline is used in determining 0.1 to 2.5 p.p.m. of hydrogen peroxide and 4,7-diphenyl-1,10-phenanthroline is used for the 0.03- to 0.1 -p.p.m. range.
- Allsopp
Phenanthroline and Substituted Phenanthroline Indicators
- G F Smith
- F P Richter
- Smith