Determination of organophosphorus pesticides in fruits by on-line size-exclusion chromatography-liquid chromatography-gas chromatography-flame photometric detection.

The determination of organophosphorus pesticides in fruits by size-exclusion chromatography (SEC) on a polystyrene column coupled on-line to a gas chromatography (GC) system was unsatisfactory as a result of interfering peaks in GC. A liquid chromatography step on silica gel was therefore inserted between the SEC and GC steps to filter out polar by-products. Samples of fruit (apples, grapes and kiwi fruits) were extracted, then the extract filtered or centrifuged and injected into an automated on-line SEC-liquid chromatography-GC-flame photometric detection. Recoveries were about 95% and the detection limits about 1 ng/g.