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