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Diphenyl Carbazide method to test chromate conversion coatings on aluminum?

Lab services        

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I'd like to test an aluminum product that has a chromate conversion coating on traces of hexavalent chromium. Can I use the Diphenyl Carbazide method of ISO 3856-5 for this or can this method only used for chromium containing paints?

Secondly, I heard that for the Diphenyl Carbazide method to work, the coating cannot be older than three days. Is this true?

Thanks in advance for all replies.

Jaap Hoftijzer
automotive supplier - The Netherlands

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Hi,

First, you need to do TCLP(Toxicity Characteristics Leaching Procedure)

Toxic Characteristic Leaching Procedure (TCLP) is an EPA SW-846 analytical method (Method 1311) that simulates sanitary landfill contaminant leaching in waste samples.

Hexavalent chromium reacts with diphenylcarbazide under acid conditions to form a red-violet color(diphenylcarbazide-dichromate complex). Results are quantified photometrically or by visual comparison with standards.

Brian Chang
- Taiwan

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Hello!
My name is Katya and I'm a student for biotechnology in Israel, and I'm doing a presentation about "Survival and chromate reducing ability of Pseudomonas aeruginosa in industrial effluent".
One of the methods to estimate the residual Cr(VI) in the culture supernatant fluid is by S-diphenyl carbazide, and I wonder if you can give me some information about this method, like how this method works and the principle of this method.
sincerely,

Katya Samonin
- Karmiel, Israel

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March 10, 2009

Hello!
My name is Iftekhar and I'm a student of microbiology in Bangladesh, and I'm doing a research on "bioremediation of chromium by local bacterial isolates".
One of the methods to estimate the residual Cr(VI) in the culture supernatant fluid is by S-diphenyl carbazide, and I wonder if you can give me some information about this method, like how this method works and the principle of this method.
sincerely,

Department of microbiology
University of Dhaka

Iftekhar Md. Rafiqullah
- Dhaka, BANGLADESH