MULTI-RESIDUE PESTICIDE ANALYSIS IN ENVIRONMENTAL WATER SAMPLES USING SOLID-PHASE EXTRACTION DISCS AND GAS-CHROMATOGRAPHY WITH FLAME THERMIONIC AND MASS-SELECTIVE DETECTION

A multi-residue analysis for 25 pesticides was developed as a rapid screening method for organic contaminants in river, lake and sea water samples. Gas chromatography with flame thermionic detection (GC-FTD) and mass selective detection (GC-MSD) using two different capillary columns, DB-1 and HP-5, was employed for the identification of 25 selected pesticides belonging to triazines, organophosphorus compounds and substituted ureas, carbamates, anilides, anilines and amides. The extraction of various natural waters spiked with pesticide mixtures was effected with C-18 Empore solid-phase extraction discs and filter-aid glass beads. The triazine compounds (atrazine, simazine, propazine, prometryne and cyanazine) were recovered from distilled and underground water samples at relative high levels (73.5-105%) compared with the river waters (39.9-80.5%), lake water (54.6-81.8%) and marine water (38.6-79.9%). The organophosphorus compounds studied (monocrotophos, terbufos, diazinon, methyl parathion, ethyl parathion, malathion and ethion) were also recovered from distilled and underground water samples at relatively high levels (62.4-118%) compared with river waters (27.3-98.9%), lake water (41.0-85.2%) and marine water (33.4-81.3%). The substituted ureas (monuron, diuron and linuron), substituted anilines and anilides (trifluralin, propanil, propachlor and alachor), carbamates (EPTC and carbofuran) and other compounds (molinate, picloram, captan and MCPA isooctyl ester) were recovered at the same level as triazines. Confirmation of pesticide identity was performed by using GC-MS in the selected-ion monitoring mode.