FEASIBILITY OF SCREENING LARGE AQUEOUS SAMPLES FOR THERMALLY UNSTABLE PESTICIDES USING HIGH EFFICIENCY PACKED COLUMN SUPERCRITICAL FLUID CHROMATOGRAPHY WITH MULTIPLE DETECTORS

摘要

Nearly 100 pesticides were eluted with good peak shapes from silica columns using methanol/carbon dioxide mobile phases. The pesticides included organophosphorus, organochlorine, phenylurea, sulfonylurea, triazine, carbamate and phenoxyacid pesticides, demonstrating the wide applicability of SFC to pesticide analysis. A subset of 31 pesticides were on-line extracted from large water samples, typically 10 to 20 ml, but up to 100 ml. The extracts were separated on a 1.6 meter long column packed with 5 mu m particles, then detected simultaneously with a photodiode array UV detector plus an electron capture (ECD) and a nitrogen-phosphorus (NPD) detector. Recovery, reproducibility, linearity, response factors and detection limits were determined. Detection limits from a 5 ml water sample were in the range of 100 to 500 parts per trillion (1/10(12)). Larger samples appear capable of lowering these limits to below 10 ppt. [References: 38]