Direct multiparametric determination of anions in soil samples by integrating on-line automated extraction/filtering with capillary electrophoresis

An integrated continuous flow-capillary electrophoresis for the determination of soluble anions in soil samples is presented. A filtration probe coupled with the flow system, which is located before the capillary electrophoresis instrument, was designed to simplify sample pretreatment and to perform clean-up of aqueous soil suspensions. Only the manual weighing of the samples is needed. The extraction process for soil samples was optimized. The clear filtrate containing the soluble anions from soil was then passed to the capillary electrophoresis equipment by a home-made programmable arm. Chloride, sulfate, nitrite and nitrate were determined in soil samples at μg g^–1 level and the results compared to manual reference methods. The precision expressed as relative standard deviation was in the range of ± 1.6 to ± 2.5% for the set of analytes determined. The procedure is up to 4 times faster than the competitive manual methods. Received: 29 July 1997 / Revised: 10 September 1997 / Accepted: 13 September 1997