SOLID-PHASE EXTRACTION AND DETERMINATION OF CARBAMATE PESTICIDES IN WATER SAMPLES BY REVERSE-PHASE HPLC

Solid phase extraction, SPE, using C-18 bonded phase silica cartridges for trace amounts determination of carbaryl, propoxur, thiram, propha m and methiocarb in water samples was studied and the breakthrough vol ume of the cartridges was established. The high enrichment factor and large injection volume admissible in the isocratic reverse-phase HPLC system allows pesticides determination with UV detection at 220 nm eve n at a concentration lower than 0.05 mu g/L. Purified, tap, natural an d underground water samples were spiked with carbamate pesticides in t he concentration range 0.16 - 16.0 mu g/L. Large volumes of samples (u p to 2L) were passed through available C-18 cartridges and eluted with acetonitrile. The preconcentrated samples were analyzed by HPLC using a Spherisorb ODS column with a 42:58 acetonitrile-water mobile phase. From replicate samples, recovery for the pesticides ranged from 79.0 to 103.7% except for thiram which is not retained. The relative standa rd deviation (n = 4 at 0.16 to 1.61 mu g/L concentration level) ranged from 1.1 to 6.8%.