Browse Prior Art Database

Composition Change to Diphenylcarbazide Reagent

IP.com Disclosure Number: IPCOM000083703D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Lozier, RG: AUTHOR

Abstract

S-diphenylcarbazide reagent is utilized in the colorimetric determination of hexavalent chromium. The method is applicable to continuous waste-water analyzers where hexavalent chromium is the species to be monitored.

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Composition Change to Diphenylcarbazide Reagent

S-diphenylcarbazide reagent is utilized in the colorimetric determination of hexavalent chromium. The method is applicable to continuous waste-water analyzers where hexavalent chromium is the species to be monitored.

Waste water containing large concentrations of calcium, forms a precipitate following the reaction between the sample and the reagent. The precipitate causes light scattering in the colorimeter section of the analyzer. This results in erratic signal response.

The standard s-diphenylcarbazide reagent employs a solution of 1,5 diphenylcarbazide in a mixture of alcohol and aqueous sulfuric acid. When the concentration of calcium in the waste water is high, the calcium forms calcium sulfate which is insoluble in the aqueous acid-alcohol mixture.

The precipitate is avoided by using concentrated hydrochloric acid instead of sulfuric acid. The solution is prepared by dissolving diphenylcarbazide in 100 milliliters of methyl, isopropyl or ethyl alcohol, and adding the mixture to an acid solution prepared from 70 milliliters of concentrated hydrochloric acid and 330 milliliters of distilled water. The reagent gives correct results for hexavalent chromium and eliminates interference in the analyzers.

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