Iodate In Acidic Medium Research Articles

Oxidative Degradation of Brilliant Green by Potassium Iodate in Acidic Medium: A Kinetic and Mechanistic Study

Brilliant green (BG), one of the triphenylmethane dyes, has been extensively applied and produced as a colorant for different industries like medical, paper/textile printing, food additive, cosmetics, etc. Dyes effluents discharged by these industries pose hazardous effects on environmental and human health via releasing toxic and carcinogenic contaminants during its deterioration. The present work evaluates kinetic and mechanistic aspects of oxidative degradation of brilliant green by iodate in acidic solution at 303 K. The influence of different factors such as concentration of various reactants (μ), free radicals, etc. has also been investigated to check feasibility of redox degradation for efficient, easy, low-cost and eco-friendly removal of brilliant green from aquatic medium. The experimental result shows a first-order rate dependence on [BG] and zero-order kinetics with respect to [KIO3]. The reaction showed positive fractional order dependence on the rate for [H+]. Variations in ionic strength of the medium and [Cl–] did not bring about any noticeable change on the rate of reaction. It was found that the reaction rate declined with the decrease in the dielectric constant (D) of the medium in the oxidation of brilliant green. Additionally, the process was carried out at different temperatures to estimate the activation parameters and also to find rate controlling stages of the process. Finally, an appropriate mechanism, a plausible with the experimental observations, also supported by UV-Vis spectra has been proposed.

Arsenic Monitoring in Water by Colorimetry Using an Optimized Leucomalachite Green Method.

Arsenic contamination of drinking water is a global concern. Standard laboratory methods that are commonly used for arsenic detection in water, such as atomic absorption spectroscopy and mass spectroscopy, are not suitable for mass monitoring purposes. Autonomous microfluidic detection systems combined with a suitable colorimetric reagent could provide an alternative to standard methods. Moreover, microfluidic detection systems would enable rapid and cost efficient in situ monitoring of water sources without the requirement of laborious sampling. The aim of this study is to optimize a colorimetric method based on leucomalachite green dye for integration into a microfluidic detection system. The colorimetric method is based on the reaction of arsenic (III) with potassium iodate in acid medium to liberate iodine, which oxidizes leucomalachite green to malachite green. A rapid colour development was observed after the addition of the dye. Beer’s law was obeyed in the range between 0.07–3 µg mL−1. The detection limit and quantitation limit were found to be 0.19 and 0.64 µg mL−1, respectively.

Spectrophotometric and potentiometric determination of some organophosphorus pesticides in bulk powder and in their dosage forms

Two simple, sensitive and precise methods were developed and validated for determination of diazinon, chlorpyrifos and temefos pesticides in bulk powder and dosage forms. The spectrophotometric method involves the oxidation of these pesticides with potassium iodate in acidic medium with the liberation of iodine and subsequent extraction with cyclohexane followed by measuring the absorbance at λ = 520 nm. Beer`s law is obeyed in the concentration range of 0.05–1.00 mg ml for diazinon and chlorpyrifos and 0.05–0.6 mg ml for temefos. The apparent molar absorbitivities of the resulting coloured products are found to be 0.539×103, 0.368×103 and 0.474×103 L mol−1 cm−1 for diazinon chlorpyrifos and 0.05–0.6 mg ml−1 for 0.368×103 and 0.474×103 L mol−1 cm−1 or diazinon, chlorpyrifos and temeos, respectively, whereas Sandell sensitivities are 0.5647, 0.9527 and 0.9841 µg cm −2, respectively. The potentiometric method involves the direct titration of the studied pesticides with N-bromosuccinimide in acidic medium and the end point is determined potentiometricallyusing platinum indicator electrode. The ratio of drug: NBS was 1:3 for diazinon andchlorpyrifos and 1:6 for temefos. The proposed methods were successfully applied to the analysis of the studied pesticides in bulk powder and in dosage forms without interference from other additives.

Photodegradation and photostability-indication of mequitazine

The photochemical behavior is investigated for mequitazine (MQ) illustrating possible mechanisms and photodegradation products formed. Accelerated photolysis is done for MQ under justified stress conditions by subjecting aqueous drug solutions to radiation for specified period of time. Synthesis of the main photodegradants, the sulfoxide, is achieved. Selective quantification of MQ, singly in bulk form, pharmaceutical formulations and/or in the presence of its photodegradants is demonstrated. The indication of stability has been undertaken under conditions likely to be expected at normal storage conditions using a simple colorimetric method based on oxidation of the intact phenothiazine drug by potassium iodate in acid medium to form a red colored product adequate for quantitative estimation of the studied drug.

Iodimetric assay of olanzapine in pharmaceuticals using iodate and Nile blue as reagents

A simple, selective and cost effective spectrophotometric method has been described for the determination of olanzapine (OLP) in bulk drug and in tablets. The method involves treating OLP with an excess of iodate in acid medium followed by the determination of liberated iodine by reacting with a fixed amount of Nile blue and measuring the absorbance at 400 nm. In this method, the amount of iodine reacted corresponds to the OLP concentration. The experimental conditions for the assay have been optimized and the absorbance is found to increase linearly with the concentration of OLP (r = 0.997). Beer's law is obeyed over the range 15-120 ?g mL-1. The calculated molar absorptivity and Sandell sensitivity values are 0.657?103 l mol-1 cm-1 and 0.475 ?g cm-2, respectively. The limits of detection (LOD) and quantification (LOQ) are 3.93 and 11.90 ?g ml-1. The performance of the method was validated according to the present ICH guidelines. The repeatability and intermediate precision, expressed by the RSD was better than 3%. The accuracy of the method expressed as relative error was satisfactory. The proposed method was applied to the analysis of tablet form of OLP and the results tallied well with the label claim. No interference was observed from concomitant substances normally added to tablets. The results were statistically compared with those of a literature method by applying the Student's t-test and F-test. The accuracy and validity of the method were further ascertained by performing recovery studies via spike method.

Determination of Arsenic in Environmental and Biological Samples Using Toluidine Blue or Safranine O by Simple Spectrophotometric Method

A simple spectrophotometric method has been developed for the determination of arsenic in various environmental and biological samples. The method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. This liberated iodine bleaches the blue color of toluidine blue or pinkish red color of safranine O. The decrease in absorbance at 628 or 532 nm is directly proportional to arsenic(III) concentration and obeys Beer's law in the range of 1.2-10.5 or 0.4-11.5 microg mL(-1) for arsenic(III). The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method using toluidine blue or safranine O were found to be 1.076 x 10(4) or 1.388 x 10(4) L mol(-1) cm(-1), 9.66 x 10(-3) or 7.49 x 10(-3) microg cm(-2), 0.308 or 0.250 microg mL(-1), 0.934 or 0.759 microg mL(-1) respectively. The relative standard deviation for five replicate analyses of 4 microg mL(-1) of As(III) using toluidine blue or safranine O were 0.60% or 0.80%. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described. The proposed method is free from any interference. The method has been used for the determination of arsenic in various environmental and biological samples.

A New Spectrophotometric Method for the Determination of Arsenic in Environmental and Biological Samples

A simple and selective spectrophotometric method has been developed for the determination of trace amounts of arsenic using azure B as a chromogenic reagent. The proposed method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. The liberated iodine bleaches the violet color of azure B and is measured at 644 nm. This decrease in absorbance is directly proportional to the As(III) concentration, and Beer's law is obeyed in the range 0.2–10 µg ml−1 of As(III). The molar absorptivity, Sandell's sensitivity, detection limit, and quantitation limit of the method were found to be 1.12×104 l mol−1cm−1, 6.71×10−3 µg cm−2, 0.02 µg ml−1 and 0.08 µg ml−1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples.

Spectrophotometric and potentiometric determination of piroxicam and tenoxicam in pharmaceutical preparations.

Two simple and accurate methods are described for the determination of piroxicam and tenoxicam in their pharmaceutical preparations. The spectrophotometric method involves the oxidation of these drugs with potassium iodate in acid medium with the liberation of iodine and subsequent extraction with cyclohexane followed by measuring the absorbance at lambda=522 nm. Beer's law is obeyed in the concentration range of 0.05-1.1 and 0.05-0.6 mg x ml(-1) for piroxicam and tenoxicam, respectively. The apparent molar absorptivities of the resulting coloured products are found to be 2.7 x 10(3) and 2.5 x 10(3) l mol(-1) x cm(-1), whereas Sandell sensitivities are 0.012 and 0.013 g x cm(-2) for piroxicam and tenoxicam, respectively. The potentiometric method involves the direct titration of both drugs with N-bromosuccinimide in acid medium and the end point is determined potentiometrically using platinum indicator electrode. Piroxicam and tenoxicam can be determined quantitatively in the concentration range of 0.33-3.37 and 0.33-4.08 mg x ml(-1) for tenoxicam and piroxicam, respectively. The standard deviation and relative standard deviation values are found to be ranged from 0.05-0.07 and 0.37-0.98% and 0.025-0.078 and 0.25-1.2% for tenoxicam and piroxicam, respectively. The two methods are accurate within +/-1.0%. Optimum conditions affecting both methods are studied. The proposed methods are applied for the determination of the drugs in pure form and in commercial pharmaceutical preparations.

Nonlinear dynamics in the oxidations of substituted thioureas I: The reaction of 4-methyl-3-thiosemicarbazide with acidic iodate [1

The substituted thiourea, 4-methyl-3-thiosemicarbazide, was oxidized by iodate in acidic medium. In high acid concentrations and in stoichiometric excess of iodate, the reaction displays an induction period followed by the formation of aqueous iodine. In stoichiometric excess of methylthiosemicarbazide and high acid concentration, the reaction shows a transient formation of aqueous iodine. The stoichiometry of the reaction is: 4IO + 3CH3NHC(S)NHNH2 + 3H2O 4I− + 3SO + 3CH3NHC(O)NHNH2 + 6H+ (A). Iodine formation is due to the Dushman reaction that produces iodine from iodide formed from the reduction of iodate: IO + 5I− + 6H+ 3I2(aq) + 3H2O (B). Transient iodine formation is due to the efficient acid catalysis of the Dushman reaction. The iodine produced in process B is consumed by the methylthiosemicarbazide substrate. The direct reaction of iodine and methylthiosemicarbazide was also studied. It has a stoichiometry of 4I2(aq) + CH3NHC(S)NHNH2 + 5H2O 8I− + SO + CH3NHC(O)NHNH2 + 10H+ (C). The reaction exhibits autoinhibition by iodide and acid. Inhibition by I− is due to the formation of the triiodide species, I, and inhibition by acid is due to the protonation of the sulfur center that deactivates it to further electrophilic attack. In excess iodate conditions, the stoichiometry of the reaction is 8IO + 5CH3NHC(S)NHNH2 + H2O 4I2 + 5SO + 5CH3NHC(O)NHNH2 + 2H+ (D) that is a linear combination of processes A and B. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 193–203, 2000

Solid-Phase Extraction and Spectrophotometric Determination of Iodate in Table Salt after Azo Dye Formation

Abstract A new reaction for determining iodate in table salt is proposed. It is based on oxidation of phenylhy-drazine-4-sulfonic acid by iodate in acidic medium to the 4-diazobenzenesulfonic acid cation and its electrophilic coupling with N-(1-naphthyl)ethylene- diamine dihydrochloride to give an azo dye, which is measured spectrophotometrically at 545 nm. Maximum molar absorptivity was 8.41 ×104 L/mol cm. A rectilinear calibration graph was obtained for iodate in the range 0.25–5 mg/L. The azo dye could be preconcentrated at least 40-fold by solid-phase extraction on C18 sorbent. The limit of detection was 0.6 μg iodate/L. The method was used to determine iodate in laboratory-prepared and commercially available table salt samples. Up to 5 mg bromate/kg and 10 mg iron(lll)/kg in table salt did not interfere.

Indirect spectrophotometric determination of benzylpenicillin and cloxacillin in pharmaceutical preparations

An indirect spectrophotometric method for the determination of benzylpenicillin and cloxacillin is based on extraction of iodine produced by reduction of potassium iodate in acidic medium, where hydrolytic cleavage of a β-lactam is achieved with sodium hydroxide. Beer's law is obeyed within the concentration ranges 0.04–0.8 mg ml−1 benzylpenicillin and 0.02–0.5 mg ml−1 cloxacillin. The precision, accuracy of the method and the effect of foreign substances were studied. The results have been statistically compared with those using the ammonium vanadate method. An oxidation mechanism is proposed.

ChemInform Abstract: Non‐Linear Dynamics in Chemistry Derived from Sulfur Chemistry. Part 18. Oxyhalogen‐Sulfur Chemistry. Oxidation of 2‐ Aminoethanethiolsulfuric Acid by Iodate in Acidic Medium

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Oxyhalogen–sulfur chemistry Oxidation of 2-aminoethanethiolsulfuric acid by iodate in acidic medium

The oxidation of 2-aminoethanethiolsulfuric acid, AETSA, by iodate has been studied in highly acidic media. The reaction is very slow and shows some clock-reaction characteristics in which iodine is formed after some induction period. The oxidation of AETSA involves the oxidation of only one of the sulfur atoms to SO 4 2- . The other sulfur atom remains attached to the carbon chain as a sulfonic acid (taurine). The stoichiometry of the reaction is: IO 3 - +H 2 NCH 2 CH 2 S–SO 3 H+H 2 O→ H 2 NCH 2 CH 2 SO 3 H+I - +SO 4 2- +2H + . The reaction of I 2 and AETSA was found to be slow and autoinhibitory as the I - formed combines with the remaining I 2 to form the relatively unreactive triiodide ion, I 3 - . The second-order rate constant for the reaction between I 2 and AETSA was determined as 16.7±2.3 M -1 s -1 .

Chemical enhancement method for the determination of mercury by spectrophotometry after iodide extraction

A selective and sensitive spectrophotometric method for the determination of 0.08–2.5 ppb of mercury(II) is described. Mercury is extracted as tetraiodomercury(II)—Cd—phenanthroline ion-pair into benzene and selectively stripped into EDTA. The iodide associated with mercury present in the stripping is oxidized to iodate and then treated with excess iodide to give iodine. The iodine formed is extracted into benzene and equilibrated with iodate in acidic medium in the presence of chloride and Rhodamine 6G for the formation of ICI − 2 species and its extraction as ion-pair with Rhodamine 6G. Determination is completed by measuring the absorption of the extract at 535 nm. The coefficient of variation is 1.5% for 10 determinations of 200 ng of mercury. The method has been applied to establish the mercury content of natural waters and chloralkali plant effluent.

Kinetics and mechanism of the complex oxidation of aminoiminomethanesulfinic acid by iodate in acidic medium

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and mechanism of the complex oxidation of aminoiminomethanesulfinic acid by iodate in acidic mediumElizabeth Mambo and Reuben H. SimoyiCite this: J. Phys. Chem. 1993, 97, 51, 13662–13667Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://doi.org/10.1021/j100153a039RIGHTS & PERMISSIONSArticle Views146Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (712 KB) Get e-Alerts

A chemical enhancement method for the spectrophotometric determination of trace amounts of arsenic

A highly sensitive spectrophotometric method for the determination of 0.03–1.0 μg of arsenic is described. After extraction as AsI 3 into benzene, it is selectively stripped into water. Both the arsenic(III) and iodide present in the aqueous phase are made to react with iodate in acidic medium in the presence of chloride to form the anionic chloro complex, ICl − 2. The determination is completed after extraction of ICl − 2 species as an ion-pair with Rhodamine 6G into benzene and measuring the absorption of the extract at 535 nm. The coefficient of variation is 1.5% for 10 determinations of 0.5 μg of arsenic. The method has been applied to the determination of arsenic content in plant materials, high purity iron, copper base alloys and inorganic arsenic levels of natural waters.

A rapid spectrophotometric method for the determination of carbon monoxide in ambient air

A sensitive spectrophotometric method for the determination of carbon monoxide is described, based on the reduction of palladium(II) by carbon monoxide. The resulting elemental palladium is reacted with iodate in acidic medium in the presence of chloride, to produce an ICl − n species that is readily extracted as an ion-pair with Pyronine-G into benzene. Measurement of the absorbance of the extract at 535 nm permits the determination of carbon monoxide down to 1 μl/l. in air. The effect of interfering gases is discussed. The method is suitable for determination of carbon monoxide in motor vehicle exhaust gases and ambient air.

A Precursor of Methoxy-para-benzoquinone in Wheat Germ

IN September 1952 a preliminary communication was read at the Second International Congress for Fermentation Industries held at Ostend, in which we demonstrated the formation of methoxy-para-benzoquinone from an aqueous germ extract. The method used differs from that of Vuataz1 and of Cosgrove et al.2 in that we did not use any yeast but treated our germ extract with potassium iodate in acid medium. From this we concluded that the germ extract contains the precursor of methoxy-para-benzoquinone, and we mentioned the isolation of this precursor (X).