ELECTROCHEMICAL DETECTION OF NITRITE AND NITRATE USING A MICROREDUCTOR CHAMBER

`Nitric oxide (NO) is quickly oxidized to nitrite and nitrate in aqueo us and biological solutions, making direct measurement of this labile compound difficult, Quantitative analysis of nitrite and nitrate has b een used extensively as an indirect measurement of endogenous producti on of NO in biological systems, The colorimetric reaction of nitrite w ith Griess reagent is probably the most commonly used technique for an alysis of total nitrite and nitrate, This technique is useful for the measurement of basal NO production with a lower detection limit of 25 nM, yet is not suitable for kinetic studies and suffers from interfere nce from free thiols, proteins and other plasma constituents(1,2). Fur thermore, only a limited number of samples can be analysed at a time o n a continuous basis because the development of the colour reaction ma y take 5 min or more. Here we report an electrochemical method of dete ction of nitrite and nitrate, which has several advantages over photom etric analysis.