DIRECT DETERMINATION OF NITRATE AND NITRITE IN SOILS BY USE OF A HYDRODYNAMIC INJECTION PROBE BASED ON FILTRATION-DIALYSIS PROCESSES

A flow System integrating a soil sample pretreatment unit and a flow m anifold was developed for the sequential determination of nitrate and nitrite. The pretreatment unit comprises a probe where filtration and dialysis are performed in order to clean-up aqueous soil suspensions. The flow manifold is a straightforward configuration including a coppe rized cadmium minicolumn in a bifurcated channel for the sequential de termination of nitrate and nitrite. The analytes were determined at th e microgram per gram level in soils with relative standard deviations between +/-3 and +/-5%.