What causes the Nitrate and Nitrite Test Strips (catalog number 2745425) to change color?

Document ID

Document ID TE3479

Published Date

Published Date 27/05/2017
Question
What causes the Nitrate and Nitrite Test Strips (catalog number 2745425) to change color?
Summary
Color change on Nitrate and Nitrite Test Strips (catalog number 2745425)
Answer
The pad on the strip contains a metal reducing agent that will reduce the Nitrate to Nitrite. Once reduced to nitrite, under acidic conditions, the sample will diazotize with an aromatic amine (sulfanilamide). This diazo compound will then couple with another aromatic amine (1,2,3,4-Tetrahydro-benzo[h]quinolin-3-ol (HTBQ)) which produces a pink-violet color used to indicate the concentration of Nitrate and Nitrite. This reaction is a modified Griess Reaction.
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