Landolt Reaction Research Articles

Iodine clock reaction mechanisms

Outlines the mechanism for the simple iodine clock reaction and the Old Nassau modification.

ChemInform Abstract: KINETIC TRACE DETERMINATION OF MOLYBDENUM(VI), L‐ASCORBIC ACID, AND THIOSULFATE USING THE LANDOLT REACTION BY THE AID OF FLUOROMETRY

Chemischer InformationsdienstVolume 15, Issue 34 Other Subjects ChemInform Abstract: KINETIC TRACE DETERMINATION OF MOLYBDENUM(VI), L-ASCORBIC ACID, AND THIOSULFATE USING THE LANDOLT REACTION BY THE AID OF FLUOROMETRY M. KATAOKA, M. KATAOKASearch for more papers by this authorH. HEMMI, H. HEMMISearch for more papers by this authorT. KAMBARA, T. KAMBARASearch for more papers by this author M. KATAOKA, M. KATAOKASearch for more papers by this authorH. HEMMI, H. HEMMISearch for more papers by this authorT. KAMBARA, T. KAMBARASearch for more papers by this author First published: August 21, 1984 https://doi.org/10.1002/chin.198434347AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue34August 21, 1984 RelatedInformation

Kinetic Trace Determination of Molybdenum(VI), l-Ascorbic Acid, and Thiosulfate Using Landolt Reaction by the Aid of Fluorometry

Abstract Trace amounts of molybdenum(VI) can be determined by the use of their catalytic effects on the peroxoborate–iodide redox reaction in acidic medium. The indicator reaction is transformed to a Landolt reaction by the addition of ascorbic acid into the reaction mixture, i.e., the iodine produced by the reaction is immediately reduced by ascorbic acid. The end of the induction period of the Landolt process was fluorometrically detected by the aid of disappearence of fluorescence of Rhodamine B. Trace determination of molybdenum(VI) was carried out by employing the linear relationship between the reciprocal of induction period and catalyst concentration. The most suitable concentrations of sodium peroxoborate, potassium iodide, and hydrochloric acid in the reaction mixture were found to be 9 mM, 0.1 M, and 0.1 M, respectively. By this method, molybdenum(VI) can be determined from 80 nM to 10 mM (7.675 ng ml−1 to 95.95 mg ml−1). The effect of foreign ions were studied and an equal amount of tungsten(VI), and 10-fold amounts of zirconium(IV), iron(II), iron(III), vanadium(IV), and copper(II) were found to show interference. Ascorbic acid and thiosulfate in micro mol l−1 levels were also determined by the present method employing the linear relationship between the induction period and the reductant concentration.

Application of iodide ion-selective electrode to catalymetric determination of micro amount of tungsten (VI) by the aid of Landolt reaction

Application of iodide ion-selective electrode to catalymetric determination of micro amount of tungsten (VI) by the aid of Landolt reaction

A novel synthesis of 3,5-diiodotyrosine with iodic acid

Based on Landolt's reaction between iodic acid and sulfite to produce iodine, a method has been developed for the high-yield iodination of tyrosine to form diiodotyrosine without significant formation of monoiodotyrosine. The use of sulfite as reductant for iodic acid cannot be effectively replaced by citric or oxalic acid under the reaction conditions.

Determination of copper traces in grass using a catalytic method

A catalytic method, based on the peroxodisulphate-bromide-ascrobic acid Landolt reaction, is described for the determination of 2–50×10−4% copper in dry grass samples. 1 g sample is dry-ashed first, then treated with hydrochloric acid and subjected to catalytic analysis. Using potentiometric monitoring, the Landolt reaction times are determined from the potentiograms. Results are evaluated from these using a calibration graph. They agree well with those obtained through atomic absorption or plasma emission spectroscopy. Relative standard deviations are less than 2% with reaction times of 1–7 min.

Determination of molybdenum by the catalysed peroxyacetic acid—iodide—ascorbic acid reaction

A new catalytic method for the determination of 0–10 ppm molybdenum is described. Molybdenum catalyses the peroxyacetic acid—iodide—ascorbic acid Landolt reaction at pH 4.2. The rate is monitored by potentiometry, and results are evaluated from a calibration graph. Optimal conditions for the determination are discussed and interferences are described. The stoiehiometry, mechanism and kinetics of both the uncatalysed and the catalysed reactions were investigated, and the rate constants (for 20°C) as well as the entropies and enthalpies of activation of both the uncatalysed and the catalysed reactions are reported.

Iodine Clock Oscillating Reaction

Iodine Clock Oscillating Reaction

Rossini, William Tell and the iodine clock reaction: A lecture demonstration

The iodine clock reaction is timed to coincide with three portions of the William Tell Overture.

A simple device for determinations using Landolt reactions

A device has been described which permits several Landolt reactions to be initiated simultaneously. All solutions remain at the same temperature, and mixing is rapid. This device improves the precision and the convenience of determinations using Landolt reactions.

Determination of traces of copper by the catalysed peroxodisulphate—bromide—ascorbic acid Landolt reaction

The reaction between peroxodisulphate and bromide has been utilized for the catalytic determination of 0–1 ppm of copper in dissolved samples. The kinetics and mechanism of the uncatalysed and catalysed reaction have been studied, and the most important kinetic parameters determined. Under the experimental conditions described, the determination can be carried out in the presence of large numbers of other ions with an error less than 5%.

A catalytic-kinetic method for the determination of traces of fluoride in biological material

A catalytic-kinetic method for the determination of nanogram amounts of fluoride, based on its inhibiting action on the catalyst in the zirconium-catalyzed reaction between perborate and iodide, is described. The rate measurements are accomplished very simply by using a Landolt reaction system with a biamperometric detection of the induction period. The standard deviation in the working range 19–190 ng of fluoride (1–10 nmol) is ± 2 ng. The method can be made specific by combining it with a separation of the fluoride by microdiffusion. This has been demonstrated by analyzing biological material and comparing the results with the fluoride contents obtained with other methods.

A combined titration calorimeter and fixed wavelength colorimeter

A combined titration calorimeter and fixed wavelenth LED colorimeter is described. The appears consists of a conventional thermistor-Dewar calorimeter and includes a LED light source—light pipe-phototransistor colorimeter. Not only can the temperature change of the reacting system be recorded but the color change of the solution as well. The use of the apparatus is illustrated with the acid—base (indicator) reaction, iodine and formaldehyde clock reactions, and an oscillating iodine clock reaction.

An oscillating iodine clock

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAn oscillating iodine clockThomas S. Briggs and Warren C. Rauscher Cite this: J. Chem. Educ. 1973, 50, 7, 496Publication Date (Print):July 1, 1973Publication History Received3 August 2009Published online1 July 1973Published inissue 1 July 1973https://doi.org/10.1021/ed050p496RIGHTS & PERMISSIONSArticle Views6156Altmetric-Citations262LEARN 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 (795 KB) Get e-Alerts Get e-Alerts

The use of Landolt reactions in quantitative microanalysis

The use of Landolt reactions in quantitative microanalysis

The application of Landolt reactions in quantitative catalytic analysis

The place of Landolt reactions among quantitative catalytic methods is reviewed. By measuring the time lapse of the incubation period of a Landolt reaction (the reaction time) and plotting its reciprocal values versus catalyst concentration, a calibration graph can be obtained. The advantages of the use of Landolt reactions are as follows: there is no need for instrumentation and temperature control is simple. Theoretical backgrounds of the method are presented on a kinetic basis. During the analyses the uncatalysed and the catalysed reactions proceed simultaneously. The uncatalysed reaction can be examined separately if reaction time measurements are taken in the absence of the catalyst. Having obtained the velocity constant of the former, results of measurements of the reaction times of the simultaneous reactions can be evaluated to obtain the velocity constant of the catalysed reaction alone. The experimentally obtained calibration graph shows a linear correlation between reciprocal reaction time versus catalyst concentration; the rigorous kinetic examination, however, yields to a partly exponential correlation. By expanding the exponential member into a Taylor series and examining the error that arises by neglecting the non-linear members the simple linear correlation can be explained. Sensitivity, selectivity and precision of the methods are briefly discussed.

The use of Landolt reactions in quantitative microanalysis

Abstract A method is described for the estimation of 1.0–10 μg/ml of vanadium in the presence of various interferences, using the bromate-iodide reaction converted to a Landolt process. The interferences of Mo, Ti, Cu(II) and Fe(II) were found to be masked effectively by a 1000:1 excess of citrate ion. The time lapse for the occurrence of the Landolt effect is shown to be reciprocally proportional to vanadium concentration. Statistical methods are used to calculate the equation and confidence limits for the calibration curve. The effect of a number of other ions is reported.

Kinetics of color development in the Landolt ("iodine clock") reaction

Kinetics of color development in the Landolt ("iodine clock") reaction

Reaction Rates and Equilibria A. Rate of Reaction 1. Effect of concentration

Demonstrations of the effect of concentration on the rate of a reaction include H2O2+Cu(NH3)4++, Zn+acid, and the long delay iodine clock reaction.

The use of Landolt reactions in quantitative microanalysis: I. Theoretical backgrounds of a new analytical principle

Landolt-type reactions can be applied with advances in quantitative catalytic analyses. Almost all slow reactions can be transformed to a Landolt type, and reaction times, defined by the time elapse from the mixing of the solutions until the occurrence of the Landolt effect, can easily be measured. Transformation of the hydrogen peroxide-iodide reaction in a Landolt-type reaction is described, and its use for the determination of molybdenum is outlined. Kinetics of the hydrogen peroxide-iodide Landolt reaction, and that in the presence of molybdenum, were studied. Order of the reactions and velocity constants were determined. On the basis of these results a correlation between reaction time and molybdenum concentration, i.e., the shape of calibration curves, could be theoretically forecast. Similar treatments can precede other quantitative catalytic analytical methods.