by discrete sequential analysers based on the loop flowtechnique, by continuous flow technique or, when only small sample volumes are available, bymicrotiter
plate readers (MR) in absorbance mode. The latter method requires only 0.5 mL of a sample for nitrite and nitrate quantification and has a precision of 2%. The limit of detection of the MR technique is comparable to conventionalmethods
using a 1 cm cuvette (0.4 μMfornitrate,0.07μMfor nitrite).