The sensitivity, accuracy and precision of the systems decreased in the order ST>SAM>SP. The detection limits were 1.4 ng NOT-N ml-’ and 1.1 ng NOT-N ml-’ for SAM, 1.6 ng NO,-N ml-’ and 1.2 ng NOT-N ml-’ for SP, and 1.0 ng NO;-N ml-’ and 0.75 ng NOT-N ml-’ for ST, respectively. The preconcentration factors are 8, 5 and 6 for SAM-NS, SP-NS and ST-N& respectively. Interferences from various foreign ions have been studied and the methods have been applied to the determination of ng ml-’ levels of nitrite and nitrate in soil and water samples