DETERMINATION OF ATRAZINE, ITS DEGRADATION PRODUCTS AND METOLACHLOR IN RUNOFF WATER AND SEDIMENTS USING SOLID-PHASE EXTRACTION

In order to determine the fate of the herbicides atrazine (as well as some of its degradation products) and metolachlor in water and sediments, a method was developed to extract and analyse these compounds. The two matrices were separated completely by centrifugation followed by filtration using nylon filters (0.45 mu m). Sediments were extracted with a mixture of methanol-0.1N hydrochloric acid (50:50, v/v) using a wrist-action shaker. Filtered water and extracts of sediments were adjusted to pH 4, then concentrated and purified onto two solid-phase extraction cartridges using in tandem C-18 bonded phase column atop sulfonic acid bonded column(SCX). Atrazine, deethylatrazine, deisopropylatrazine and metolachlor retained by the C-18 column were eluted with ethyl acetate. Chlorodiaminotriazine and hydroxyatrazine retained by the SCX column were eluted with a 50:50 (v/v) acetonitrile-0.1M Na2HPO4 aqueous solution (pH 8.5). The extracts were quantified by high performance liquid chromatography with diode array detector (HPLC-DAD) and by gas chromatography with nitrogen-phosphorus detector (GC-NPD). Overall percent recoveries were about 75% and detection limits were between 0.05 and 0.15 mu g/l., and 0.5 and 1.5 mu g/kg for water and sediments, respectively.