Minimization of a sodium dithionite-derived interference in nitrate reductase-methyl viologen reactions |
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Authors: | David R. Senn Peter W. Carr Leon N. Klatt |
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Affiliation: | 1. Department of Chemistry, University of Georgia, Athens, Georgia 30602 USA |
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Abstract: | The use of sodium dithionite as the reducing agent to produce the radical cation of methyl viologen cofactor for the nitrate reductase-catalyzed reduction of nitrate to nitrite causes a negative interference in the diazonium salt azo dye determination of nitrite. The interference results from bisulfite, a reaction product of dithionite, reacting with the diazonium salt formed from nitrite and sulfanilamide. Addition of formaldehyde before the diazotization reaction masks this interference but at low acidity introduces a nonlinearity in the nitrite calibration curve. This nonlinearity is due to a competing reaction of formaldehyde with sulfanilamide to yield a Schiff base and can be eliminated by increasing the HCL content of the sulfanilamide reagent. |
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Keywords: | Oak Ridge National Laboratory. Author to whom correspondence should be addressed. |
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