Rapid simultaneous determination of nitrate and nitrite on a centrifugal microfluidic device

A centrifugal microfluidic device was developed for the rapid sequential determination of two critical environmental species, nitrate and nitrite, in water samples. The nitrate is reduced to nitrite and the nitrite is derivatized. The analytes are determined spectrophotometrically through the disc with a 1.4 mm pathlength. The detection limits are 0.05 and 0.16 mg L−1 for nitrite and nitrate respectively. The use of powdered reagents, the 100 μL sample required and the design of the device suggest that it would be suitable for field use.