Rapid spectrophotometric determination of trace amounts of chromium using variamine blue as a chromogenic reagent

Narayana, B.; Cherian, Thomas

doi:10.1590/s0103-50532005000200011

Cited by 11 publications

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“…But if it is in excess, Cr (OH) 6 -3 can bind with Cr (III)-DPC complex to give positive interference in detection of Cr (VI) by standered DPC method (11). To overcome this interference by Cr (III), variamine blue is used as chromogenic reagent in detection of Cr (VI) because the mechanism of action in this case is different.…”

Section: Resultsmentioning

confidence: 99%

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A new method in estimation of total hexavalent chromium in Portland pozzolan cement

Sharma

2017

Mater. construcc.

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ABSTRACT:Variamine blue was used first time for the detection of hexavalent chromium from cement samples. In present method, cement was treated sequentially with water, sulphate and carbonate buffer to extract soluble, sparingly soluble and insoluble hexavalent chromium respectively. Extracted Cr (VI) was determined using variamine blue as chromogenic reagent. The determination is based on the reaction of hexavalent chromium with potassium iodide in an acid medium to liberate iodine. This oxidizes variamine blue to form a violet coloured species having an absorption to maximum at 556 nm. Energy-dispersive X-ray spectroscopy (EDX) and Infrared Spectroscopy (IR) confirmed the complete extraction of hexavalent chromium by sequential extraction process. SRM 2701 (Reference material from NIST, USA) was used for revalidating the results. The percentage of recovery for proposed and reference method (diphelycarbazide method) varied from 98.5 to 101 and 97.5 to 100.5. Whereas, their relative error percentage varied from -1.5 to 0.33 and -2.5 to 0.5. RESUMEN:Un nuevo método en la determinación del cromo hexavalente total en cemento Portland puzolánico. El azul de variamina se utilizó por primera vez para la detección de cromo hexavalente en muestras de cemento. En el presente método, el cemento se trató secuencialmente con agua, y tampones sulfato y carbonato para extraer el cromo hexavalente soluble, poco soluble e insoluble, respectivamente. El Cr (VI) extraído se determinó utilizando azul de variamina como reactivo cromógeno, por reacción del cromo hexavalente con yoduro de potasio en un medio ácido para liberar yodo. Esto oxida al azul de variamina para formar una especie de color violeta con una absorción máxima a 556 nm. El análisis por energía dispersiva de rayos X (EDX) y la espectroscopía de infrarrojos (IR) confirmaron la extracción completa de cromo hexavalente mediante el proceso de extracción secuencial. Se utilizó SRM 2701 (material de referencia de NIST, EE.UU.) para validar los resultados. El porcentaje de recuperación para el método propuesto frente al de referencia (método de la difenilcarbazida) varió de 98.5 a 101 y 97.5 a 100.5, mientras que su porcentaje de error relativo varió de -1.5 a 0.33 y -2.5 a 0.5.

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Section: Resultsmentioning

confidence: 99%

“…Recently, variamine blue had been used for detection of hexavalent chromium in steel, industrial effluents, natural water samples and soil samples (11). Simple reaction conditions, no extraction or heating and high colour stability has made variamine blue a better reagent than others (11).…”

Section: Introductionmentioning

confidence: 99%

A new method in estimation of total hexavalent chromium in Portland pozzolan cement

Sharma

2017

Mater. construcc.

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“…In this work, the liberated iodine was allowed to react with the VB dye in the presence of sodium acetate (reaction 2). Variamine blue is known to be a suitable chromogenic reagent for iodine (Revansiddapa and Kumar 2001;Narayana and Cherian 2005;Coo and Martinez 2004). The liberated I 2 oxidizes the dye to a violet color whose absorbance maxima is at 550 nm.…”

Section: Iodometric Reactionmentioning

confidence: 99%

A rapid assessment method for determination of iodate in table salt samples

Kulkarni

Dhar²,

Kulkarni

2013

J Anal Sci Technol

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Background: In the present work, a simple and rapid method for determination of iodate is described. Methods: Iodometric reaction between iodate, excess iodide, and acid has been used, and the iodine liberated is allowed to react with variamine blue (VB) dye in the presence of sodium acetate to yield a violet-colored species. Results: A calibration curve was obtained in the concentration range of 2 to 30 μg of iodate in a final equilibration volume of 10 mL. The effect of different interfering anions on determination of iodate was also studied.

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“…The kinetics and mechanism of oxidation of chromium(VI) has been well studied, chromic acid being one of the most versatile available oxidizing agents, reacting with diverse substrates. Now a day the development of newer chromium(VI) reagents [5][6][7][8][9][10][11] for the oxidation of organic substrates continues to be of interest. Chromium is one of the most widely distributed heavy metals in the earth's crust.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation of Oxidation of Aromatic Primary Alcohol by Polymer Supported Oxidizing Agent

2016

Chem Sci Trans

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The kinetic of chromium(VI) catalyzed oxidation of 1-phenylalcohol has been studied by the rate of disappearance of [Cr(VI)]. The reaction is zero order with respect to [Cr(VI)]. The reagent supported on anion exchange resin was found to be more efficient in the oxidation reaction. The reagent is very easily separated from the reaction mixture and can be manually removed from the reaction mixture, which remains clear during and after the reaction. The kinetic of oxidation of 1-phenylethanol with chromic acid supported on anion exchange resin like Amberlite IRC-178 [Cl-] in 1, 4-dioxane has been studied. The reaction is found to be of zero order each in concentration of alcohol and oxidant. The reaction constants involved in the mechanism and the activation parameters have been calculated. There is a good agreement between observed and calculated rate constants under different experimental conditions. Acetophenone was detected as end product.

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Rapid spectrophotometric determination of trace amounts of chromium using variamine blue as a chromogenic reagent

Cited by 11 publications

References 0 publications

A new method in estimation of total hexavalent chromium in Portland pozzolan cement

A new method in estimation of total hexavalent chromium in Portland pozzolan cement

A rapid assessment method for determination of iodate in table salt samples

Mechanistic Investigation of Oxidation of Aromatic Primary Alcohol by Polymer Supported Oxidizing Agent

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