Colorimetric determination of nitrate and nitrite in milk and milk powders – Use of vanadium (III) reduction

A manual method is described for the determination of nitrate and nitrite in milk and milk powders that is intended to provide an alternative to conventional manual methods accomplished by cadmium reduction. Reduction of nitrate is performed in solution utilising vanadium (III) and quantitation achieved by concurrent reaction with Griess reagent. Performance data are acceptable in terms of precision and accuracy, repeatability being about 6% and intermediate precision at 8% for both analytes, providing the limit of detection is not approached. Limit of quantitation is 0.1 mg kg−1 for both analytes.