Oxidimetric Reagent Research Articles

Titrimetric and Spectrophotometric Assay of Pantoprazole in Pharmaceuticals Using Permanganate

Titrimetric and spectrophotometric assay of pantoprazole sodium (PPS) using permanganate as the oxidimetric reagent is described. In titrimetry, PPS is treated with a measured excess of permanganate in H2SO4 medium followed by the determination of unreacted oxidant by back titrating with a standard iron(II) solution. Spectrophotometry involves addition of a known excess of permanganate to PPS in H2SO4 medium followed by the measurement of absorbance of the residual permanganate at 545 nm. In both the methods, the amount of permanganate reacted corresponds to the PPS content. Experimental conditions that provide wide linear range, maximum sensitivity and selectivity, and accuracy and precisions have been optimized. In titrimetry, the calculations are based on a 1:1 (PPS : KMnO4) reaction stoichiometry and the method is applicable over 1.0-7.0 mg range. In spectrophotometry, Beer’s law is obeyed over the concentration range 15.0-150.0 µg mL-1. The linear regression equation of the calibration graph is A = 0.78 + 0.005 C with a regression coefficient (r) of 0.9982 (n = 11). The apparent molar absorptivity is calculated to be 2.213 × 103 l mol-1cm-1 and the Sandell sensitivity is 0.1954 µg cm-2. The limits of detection (LOD) and quantification (LOQ) calculated as per the ICH guidelines are 0.73 and 2.21 µg mL-1, respectively. Accuracy and precision of the assays were determined by computing the intra-day and inter-day variations at three different levels of PPS; the intra-day and inter-day RSD was < 3.09 % and the accuracy was better than 3.5 %. The methods were successfully applied to the determination of PPS in three different brands of tablets with good accuracy and precision, and without detectable interference by excipients. The accuracy was further ascertained by placebo blank and synthetic mixture analyses and also by recovery experiments via standard-addition procedure.

Determination of ferrous and total iron in refractory spinels

Accurate and precise determination of the redox state of iron (Fe) in spinels presents a significant challenge due to their refractory nature. The resultant extreme conditions needed to obtain complete dissolution generally oxidize some of the Fe(II) initially present and thus prevent the use of colorimetric methods for Fe(II) measurements. To overcome this challenge we developed a hybrid oxidimetric/colorimetric approach, using Ag(I) as the oxidimetric reagent for determination of Fe(II) and 1,10-phenanthroline as the colorimetric reagent for determination of total Fe. This approach, which allows determination of Fe(II) and total Fe on the same sample, was tested on a series of four geochemical reference materials and then applied to the analysis of Fe(Ni) spinel crystals isolated from simulated high-level-waste (HLW) glass and of several reagent magnetites. Results for the reference materials were in excellent agreement with recommended values, with the exception of USGS BIR-1, for which higher Fe(II) values and lower total Fe values were obtained. The Fe(Ni) spinels showed Fe(II) values at the detection limit (ca. 0.03 wt% Fe) and total Fe values higher than obtained by ICP-AES analysis after decomposition by lithium metaborate/tetraborate fusion. For the magnetite samples, total Fe values were in agreement with reference results, but a wide range in Fe(II) values was obtained indicating various degrees of conversion to maghemite. Formal comparisons of accuracy and precision were made with 13 existing methods. Accuracy for Fe(II) and total Fe was at or near the top of the group. Precision varied with the parameter used to measure it but was generally in the middle to upper part of the group for Fe(II) while that for total Fe ranged from the bottom of the group to near the top.

Quantitative Spectrophotometric Determination of Propranolol Hydrochloride in Pharmaceuticals Using Cerium(IV) Sulphate as Oxidimetric Reagent

Two simple, selective and economic spectrophotometric methods have been developed and validated for the analysis of the propranolol hydrochloride (PPH) in bulk drug and pharmaceuticals. The methods are based on the oxidation of PPH with cerium(IV) in acid medium and subsequent measurement of the excess cerium(IV) either by its reaction with p-dimethylamino benzaldehyde (p-DMAB) and measuring the resulting color at 460 nm (method A) or by its reaction with sulphanilic acid (SAA) to give a pink colored product peaking at 540 nm (method B). The decrease in the absorption intensity of the colored products, due to the presence of the drug has been correlated with its concentration in the sample solution. Different experimental variables affecting the reaction are carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients are found in the concentration ranges of 0.4–7.0 μg ml−1 for method A and 10–200 μg ml−1 for method B, respectively. The calculated molar absorptivity values are 3.72 × 104 for method A and 1.43 × 103 for method B. The methods have been validated for accuracy, precision, ruggedness and robustness and the results are found to be satisfactory. The proposed methods are successfully applied to the determination of PPH in pure and pharmaceutical dosage forms without any interference from the common excipients. The results obtained by the proposed methods are comparable with those obtained by the official methods.

Titrimetric assay of ofloxacin in pharmaceuticals using cerium(IV) sulphate as an oxidimetric reagent

Two titrimetric methods which are simple, rapid, cost-effective and eco-riendly are described for the determination of ofloxacin (OFX) in bulk drug and in tablet formulations based on the oxidation of OFX by Ce(IV) sulphate. In direct titrimetry (method A), the acidified solution of OFX is titrated directly with Ce(IV) sulphate using ferroin as indicator, and indirect titrimetry (method B) involves the addition of known excess of Ce(IV) sulphate to an acidified solution of OFX followed by the determination of unreacted oxidant by back titration with ferrous ammonium sulphate (FAS) using the same ferroin indicator. In both the methods, the amount of Ce(IV) sulphate reacted corresponds to OFX concentration. Method A and method B permit the determination of OFX over the concentration range of 1.5–15 mg in both the methods and the quantitation is based on a 1: 5 reaction stoichiometry (OFX: Ce (IV) sulphate). The methods were statistically evaluated by calculating percent relative error (% RE) for accuracy and percent relative standard deviation (% RSD) for precision, and were applied successfully to the determination of OFX in tablets with mean recoveries in the range of 96.50–98.42%. No interference was observed from common additives found in pharmaceutical preparations. The accuracy and reliability of the methods were further ascertained by performing recovery tests s standard-addition technique.

Titrimetric and Spectrophotometric Assay of Ganciclovir in Pharmaceuticals Using Cerium(IV) Sulphate as the Oxidimetric Agent

Titrimetric and spectrophotometric assay of ganciclovir (GNC) is described using cerium(IV) sulphate as the oxidimetric reagent. The methods are based on the oxidation of GNC with a measured excess of cerium(IV) sulphate in acid medium followed by determination of the unreacted oxidant by two different reaction schemes. In titrimetry, the unreacted oxidant was determined by back titration with ferrous ammonium sulphate (FAS) in sulphuric acid medium, and spectrophotometry involves the reaction of residual cerium(IV) with p-DMAB to form brownish-coloured p-dimethylamino quinoneimine whose absorbance was measured at 460 nm. In both methods, the amount of cerium(IV) sulphate reacted corresponds to GNC concentration. Titrimetry is applicable over 3–10 mg range where as, in spcetrophotometry, the calibration graph is linear over the range of 2–10 μg mL−1 and the calculated molar absorptivity value is L mol−1 cm−1. The validity of the proposed methods was tested by analyzing pure and dosage forms containing GNC. Statistical treatment of the results reflects that the proposed procedures are precise, accurate, and easily applicable for the determination of GNC pure form and in pharmaceutical formulations.

Titrimetric and spectrophotometric assay of pantoprazole in pharmaceuticals using cerium(IV) sulphate as oxidimetric agent

Titrimetric and spectrophotometric assay of pantoprazole sodium sesquihydrate (PSS) using cerium(IV) sulphate as the oxidimetric reagent is described. The methods are based on the oxidation of PSS with a measured excess of Ce(IV) sulphate followed by the determination of unreacted oxidant using different reaction schemes. In titrimetry, the unreacted oxidant was determined by back titration with ferrous ammonium sulphate (FAS) in sulphuric acid medium. Spectrophotometry involves the reduction of unreacted Ce(IV) sulphate with a fixed quantity of Fe(II). The resulting Fe(III) is complexed with thiocyanate and the absorbance is measured at 470 nm. In both the methods, the amount of Ce(lV) sulphate reacted corresponds to PSS concentration. Titrimetry is applicable over 1–10 mg range whereas in spectrophotometry, the calibration graph is linear in the range of 0.5–7.0 μg/mL and the calculated molar absorptivity value is 1.58 × 105 L/mol cm. The validity of the proposed methods was tested by analyzing pure and dosage forms containing PSS. Statistical treatment of the results reflects that the proposed procedures are precise, accurate and easily applicable to the determination of PSS in pure form and in pharmaceutical formulations.

Sensitive spectrophotometric assay of simvastatin in pharmaceuticals using permanganate

Two simple, sensitive, selective and inexpensive spectrophotometric methods are described for the determination of simvastatin (SMT) in bulk drug and in tablets using permanganate as the oxidimetric reagent. In method A, SMT is treated with a measured excess of permanganate in acetic acid medium and the unreacted oxidant is measured at 550 nm, whereas in method B the reaction is carried out in alkaline medium and the resulting manganate is measured at 610 nm. In method A, the amount of permanganate reacted corresponds to the SMT content and the absorbance is found to decrease linearly with the concentration; and in method B, the absorbance increases with concentration. The working conditions of assays were optimized, and the methods were validated according to the current ICH guidelines. Under optimum conditions, SMT could be assayed in the concentration ranges, 1.47 - 17.67x10-5 and 2.27 - 27.18 x10-6 mol/L by method A and method B, respectively. The calculated molar absorptivities are 3.2 x 10³ and 2.5 x 10(4) L/mol/cm for method A and method B, respectively with corresponding Sandell sensitivity values of 0.0387 and 0.0178 μg/cm². The limits of detection (LOD) and quantification (LOQ) have also been reported. Accuracy and precision for the assay were determined by calculating the intra-day and inter-day at three concentrations; the intra-day RSD was < 2% and the accuracy was better than 2.15 % (RE). The methods were applied successfully for the determination of SMT in tablet dosage form with a high percentage of recovery, good accuracy and precision, and without measurable interference by the excipients. The accuracy was further ascertained from placebo and synthetic mixture analysis and also from the spike-recovery method.

Determination of olanzapine by spectrophotometry using permanganate

Two new spectrophotometric methods using permanganate as the oxidimetric reagent for the determination of olanzapine (OLP) were developed and validated as per the current ICH guidelines. The methods involved the addition of known excess of permanganate to OLP in either acid or alkaline medium followed by the determination of unreacted permanganate at 550 nm (method A) or bluish-green color of manganate at 610 nm (method B). The decrease in absorbance in method A or increase in absorbance in method B as a function of concentration of OLP was measured and related to OLP concentration. Under optimized conditions, Beer's law was obeyed over the ranges 2.0 to 20 and 1.0 to 10 μg mL-1 in method A and method B, respectively. The calculated molar absorptivity values were 1.34 x 10(4) and 2.54 x 10(4) l mol-1cm-1 for method A and method B respectively, and the respective Sandell sensitivities were 0.0233 and 0.0123 μg cm-2. The LOD and LOQ for method A were calculated to be 0.37 and 1.13 μg mL-1and the corresponding values for method B were 0.16 and 0.48 μg mL-1. Intermediate precision, expressed as RSD was in the range 0.51 to 2.66 %, and accuracy, expressed as relative error ranged from 0.79 to 2.24 %. The proposed methods were successfully applied to the assay of OLP in commercial tablets with mean percentage recoveries of 102 ±1.59 % (method A) and 101 ±1.53 % (method B). The accuracy and reliability of the methods were further confirmed by performing recovery tests via standard addition procedure.

Permanganometric determination of etamsylate in bulk drug and in tablets

One titrimetric and two spectrophotometric methods which are simple, selective, sensitive, accurate, precise and economical for the determination of etamsylate (ETM) in bulk drug and in tablets employing permanganate as the oxidimetric reagent are described. In titrimetry, ETM is titrated directly with permanganate in sulphuric acid medium. A direct spectrophotometry (method A) involves treating the aqueous solution of the drug with permanganate in alkaline medium and measuring the bluish green product at 610 nm. In indirect spectrophotometry (method B), the drug solution was treated with a fixed concentration of permanganate in H2SO4 medium, and after a specified time, the unreacted permanganate was measured at 545 nm. The molar combining ratio in titrimetry and the optimum assay conditions were studied. Titrimetry is applicable over 1-10 mg range and the calculations are based on a 1:4 (ETM:KMnO4) molar ratio. In spectrophotometry, Beer's law is obeyed over 0.5- 5.0 and 1.5-15 ?g ml-1 for method A and B, respectively. The molar absorptivity values are calculated to be 2.79?104 and 4.17?104 l mol-1 cm-1 for method A and B, respectively and the corresponding sandell sensitivity values are 0.0094 and 0.0063 ?g cm-2. The limits of detection (LOD) and quantification (LOQ) are also reported for spectrophotometric methods. The applicability of the developed methods was demonstrated by the determination of etamsylate in pure drug as well as in commercial dosage forms.

Sensitive and validated spectrophotometric methods for the determination of pantoprazole sodium in pharmaceuticals using N-bromosuccinimide based on redox and complexation reactions

Two simple, sensitive and rapid methods are described for the determination pantoprazole sodium sesqui hydrate (PNT) in bulk drug and in formulations using N-bromosuccinimide (NBS) as the oxidimetric reagent. The methods involve the addition of a known excess of NBS to PNT in HCl medium followed by estimation of the unreacted oxidant by two reaction schemes involving the use of iron(II) and thiocyanate (method A) or tiron (method B). In both methods, the absorbance is found to decrease linearly with PNT concentration. Beer’s law is obeyed over the ranges 0.25-3.5 and 1-15 µg mL-1 for method A and method B, respectively. The calculated molar absorptivity values are 1.4 × 105 and 2.5 × 104 L mol-1cm-1 for method A and method B, respectively. The limit of detection (LOD) and quantification (LOQ) are also reported for both methods. The RSD values for intra-day and inter-day precision studies were less than 2.5 and 3.0 %, respectively. Both the methods were applied to the determination of PNT in dosage forms and the results were satisfactory, and were comparable with those obtained by the reference method. The accuracy and reliability of the proposed methods were further ascertained by recoveries studies, and the recoveries of the spiked drug ranged between 98.5 and 102.5 %. KEY WORDS: Pantoprazole sodium, Determination, N-bromosuccinimide, Complexation reactions, Pharmaceuticals Bull. Chem. Soc. Ethiop. 2008, 22(1), 135-141.

Quantitation of ranitidine in pharmaceuticals by titrimetry and spectrophotometry using potassium dichromate as the oxidimetric reagent

Four new methods are described for the determination of ranitidine hydrochloride (RNH) in bulk drug and in formulations employing titrimetric and spectrophotometric techniques and using potassium dichromate as the oxidimetric reagent. In titrimetry (method A), RNH is treated with a measured excess of dichromate in acid medium, and the unreacted oxidant is back titrated with iron(II) ammonium sulfate. The three spectrophotometric methods are also based on the oxidation of RNH by a known excess of dichromate under acidic conditions followed by the determination of surplus oxidant by three different reaction schemes. In one procedure (method B), the residual dichromate is treated with diphenylcarbazide and the absorbance measured at 540 nm. Calculated amount of iron(II) is added to residual dichromate and the resulting iron(III) is complexed with thiocyanate and measured at 470 nm (method C). Method D involves reduction of unreacted dichromate by a calculated amount of iron(II) and estimation of residual iron(II) as its orthophenanthroline complex after raising the pH, and measuring the absorbance at 510 nm. In all the methods, the amount of dichromate reacted corresponds to the drug content. The experimental conditions are optimized. The titrimetric procedure is applicable over 5–10 mg range. In spectrophotometric methods, Beer’s law is obeyed in the ranges 5–50, 5–80, and 10–100 µg ml−1 for method B, method C, and method D, respectively. The methods were validated for accuracy, precision and recovery. The proposed methods were applied to the analysis of RNH in the tablet and the injection forms, and the results were in agreement with those obtained by the reference method.

Titrimetric and Spectrophotometric Determination of Metaprolol tartrate in Pharmaceuticals Using N‐Bromosuccinimide

One titrimetric and two spectrophotometric methods are presented for the assay of metaprolol tartrate (MPT) in bulk drug and in tablets. The methods employ N‐bromosuccinimide (NBS) as the oxidimetric reagent and two dyes, methyl orange and indigo carmine as spectrophotometric reagents. In titrimetry, an acidified solution of MPT is treated with a known excess amount of NBS and after a definite time, the unreacted oxidant is determined by iodometric back titration. Spectrophotometry involves adding a measured excess of NBS to MPT in acid medium followed by determination of residual NBS by reacting with a fixed amount of either methyl orange and measuring the absorbance at 520 nm (Method A) or indigo carmine and measuring the absorbance at 610 nm (Method B). In all the methods, the amount of NBS reacted corresponds to the amount of MPT. Reaction conditions have been optimized. Titrimetry allows the determination of 1 ‐ 12 mg of MPT and the calculations are based on a 1: 4 (MPT: NBS) reaction stoichiometry. In spectrophotometry, the measured absorbance is found to increase linearly with the concentration of MPT serving as basis for quantitation. The systems obey Beer’s law for 0.5 ‐ 4.0 μg mL-1 and 1.25 ‐ 10.0 μg mL-1 for method A and method B, respectively. The apparent absorptivities are calculated to 1.07 × 105 be and 4.22 × 104 L mol cm-1 for method A and method B, respectively. The methods developed were applied to the assay of MPT in commercial tablet formulations, and the results were compared statistically with those of a reference method. The accuracy and reliability of the methods were further ascertained by performing recovery tests via standard‐addition method.

Determination of ranitidine hydrochloride in pharmaceutical preparations by titrimetry and visible spectrophotometry using bromate and acid dyes

Four new methods using titrimetry and spectrophotometry are described for the determination of ranitidine hydrochloride (RNH) with potassium bromate as the oxidimetric reagent and acid dyes, methyl orange, indigo carmine and metanil yellow. In direct titrimetry (method A), the drug is titrated directly with bromate in acid medium and in the presence of excess of bromide using methyl orange indicator. In back titrimetry (method B), the drug is treated with a measured excess of bromate in the presence of bromide and acid, and the unreacted bromine is determined iodometrically. Both spectrophotometric methods are based on the oxidation of RNH by a known excess of bromate in acid medium and in the presence of excess of bromide followed by estimation of surplus oxidant by reacting with either indigo carmine (method C) or metanil yellow (method D), and measuring the absorbance at 610 or 530 nm. In methods B, C and D, reacted oxidant corresponds to the drug content. The experimental conditions are optimized. Titrimetric procedures are applicable over the ranges 1–10 mg (A) and 1–17 mg (B), and the reaction stoichiometry is found to be 1:1 (BrO – 3: RNH). In spectrophotometric methods, the absorbance is found to increase linearly with increasing concentration of RNH, which is corroborated by the calculated correlation coefficient ( r) of 0.9984 (C) and 0.9976 (D). The systems obey Beer’s law for 2–12 and 1–7 μg ml –1, for methods C and D, respectively. Method D with a molar absorptivity of 9.82 × 10 4 l mol –l cm –1 is found to be more sensitive than method C ( ε = 2.06 × l0 4 l mol –1 cm –1). The limits of detection and quantification are reported for both the spectrophotometric methods. The proposed methods were applied successfully to the determination of RNH in tablets and injections. The reliability of the assay was established by parallel determination by the official method and by recovery studies.

Two simple methods for the estimation of albendazole and its dosage forms using chloramine-T

Two simple, rapid and reliable methods for the determination of albendazole are described. Both methods involve the use of chloramine-T as the oxidimetric reagent. In the titrimetric method, a known excess of chloramine-T is added to an acidified solution of sample, and after a specified time, the residual oxidant is determined iodometrically. Spectrophotometric procedure also involves the addition of a measured excess of chloramine-T in buffer medium of pH 2.70±0.1 and after the reaction is ensured to be complete, the surplus oxidant is determined by a well established colour reaction involving metol and primary arylamine that results in charge-transfer complex measurable at 520 nm. In both methods, the amount of chloramine-T corresponds to the drug content. Reaction conditions were examined and optimised. Titrimetry is based on a 1:3 stoichiometric reaction between albendazole and chloramine-T and is applicable in the range of 1–15 mg. In spectrophotometry, the absorbance was found to decrease linearly with increasing concentration of albendazole, which is corroborated by the calculated correlation coefficient value of −0.9998. The system obeys Beer's law for 2.5–25 μg ml −1 of albendazole. The molar absorptivity and Sandell sensitivity were calculated to be 6.24×10 3 l mol −1 cm −1 and 42.54 ng cm −2, respectively. The limits of detection and quantification were calculated to be 1.15 and 3.83 μg ml −1, respectively. The proposed methods were successfully applied to the determination of albendazole in commercially available dosage forms. The reliability of the assays was established by parallel determination by the official method and recovery studies.

Silver salt of N-bromo-4-methylbenzenesulfonamide as a new oxidimetric reagent

A new oxidimetric reagent, RNBrAg, where R is p-CH3C6H4SO2, is proposed for redox titrations in aqueous medium. The stability of the oxidant in aqueous medium is studied both in dark and day light for several days. Direct titration procedures have been developed for the determination of some inorganic and organic compounds using the above oxidant. The method is successfully employed for the estimation of ascorbic acid in pharmaceutical preparations. The redox potential of RNBrAg-PTS (PTS = p-toluenesulfonamide) couple has been determined at 28degrees and pH 6.92.

Iodine as an oxidimetric reagent for the determination of thiosemicarbazide and its derivatives

A sensitive, accurate and reproducible method for the determination of 10–1000 µg of thiosemicarbazide (TSC), 1-acetylthiosemicarbazide (1-ATSC), 1-phenylthiosemicarbazide (1-PTSC) and 4-phenylthiosemicarbazide (4-PTSC), involving an amplification reaction, is described. The method is based on the oxidation of the thiosemicarbazide compounds, in a hydrogen carbonate medium, with a chloroform solution of iodine, removal of the excess, oxidation with bromine of the iodide formed and titrimetric determination of the liberated iodate after six-fold amplification. The oxidation reactions involve a ten-electron change per molecule of TSC, 1-PTSC or 4-PTSC and an eight-electron change per molecule of 1-ATSC.

Use of hexamminecobalt(III)-tricarbonatocobaltate(III) as a redox titrant for the potentiometric estimation of some organic compounds

Hexamminecobalt(III)-tricarbonatocobaltate(III) was prepared, and its bicarbonate solution was standardized against ferrous ammonium sulfate using Ferroin indicator. The Co solution was used as an oxidimetric reagent for the determination of organic systems. Hydroquinone as a reversible system undergoes fast electrochemical reactions, so it can be determined with the Co(III) complex, which acts as an irreversible titrant. Thus it can be determined with both visual and potentiometric methods. Standardized hydroquinone solutions in H 2SO 4 medium gave very similar results when determined potentiometrically against standard Co(III) solution. The acid medium is important for liberating Co(III) ions. Hydrochloric acid behaves similarly but perchloric acid interferes with the reaction. Diluting the hydroquinone solutions had no effect on the determinations. The potentiometric endpoint coincides with the discharge of the color if Ferroin has been present. p-Aminophenol, p-phenylenediamine, and Metol ( p-hydroxy- N-methylaniline), which slow or hinder the electrochemical reaction, do not indicate a distinct potential change at the endpoint, so cannot be determined potentiometrically. Their chemical reactions are fast enough to be titrated visually against Co(III) complex using Ferroin indicator. Titration curves representing biamperometric measurements of these solutions fulfill these results. Hydrazine sulfate and isonicotinic acid hydrazide as irreversible systems cannot react with Co(III) and thus cannot be determined either potentiometrically or visually as both electrochemical and chemical reactions are slow to be recognized.

Redox reactions in non-aqueous media: determination of hydrazine and its organic derivatives with lead(IV) acetate

Lead(IV) acetate (in glacial acetic acid) has been described as an oxidimetric reagent for the determination of hydrazine and organic derivatives in glacial acetic acid medium. The end-points have been detected visually using quinalizarin as an indicator and potentiometrically using platinum wire indicator electrode and modified-calomel reference electrode. The method is simple, accurate, reliable and widely applicable.

Cacotheline as an oxidimetric reagent. Determination of Sn(II), Cu(I), Ti(III), Fe(II), V(II) and V(III)

Sn(II), Ti(III), Cu(I), Fe(II), V(III) and V(II) can be titrated potentiometrically with cacotheline in 1–4M hydrochloric acid, 0.5–2M hydrochloric acid, 0.5–1.5M sulphuric acid in presence of 4 ml of 10% EDTA solution in a total volume of 50 ml, 9–10M phosphoric acid, 4–8M acetic acid and 3–8M acetic acid respectively. Cacotheline can be used for the assay of tin plate and solder. The cacotheline undergoes a 2-electron reduction reaction. A cacotheline solution (0.005M) in 0.02M hydrochloric acid is fairly stable for several months. The conditional redox potentials of cacotheline have been determined in sulphuric, phosphoric and acetic acid medium.

N,N′-dichloro- p-nitrobenzenesulfonamide (dichloramine-N) as a new oxidimetric reagent: Synthesis and analytical application

A new oxidimetric reagent, dichloramine-N ( N,N′-dichloro- p-nitrobenzenesulfonamide; DCN) has been synthesized and its structure elucidated from the spectral data and elemental analyses. The ultraviolet, infrared, nuclear magnetic resonance, and mass spectral data have been presented. Analytical applications of DCN as a potential redox titrant in the determination of diverse reductants such as ascorbic acid, methionine, sulfite, arsenite, glutathione, and indigocarmine have been described.