Multiresidue method for the determination of residues of 251 pesticides infruits and vegetables by gas chromatography/mass spectrometry and liquid chromatography with fluorescence detection

A method is described for the determination of 251 pesticide and degradatio n product residues in fruit and vegetable samples. Extraction of the sample with acetonitrile is followed by a salting-out step, Co-extractives are re moved by passing a portion of the acetonitrile extract through an octadecyl (C-18) solid-phase extraction cleanup cartridge and then, in a second clea nup, through a carbon cartridge coupled to an amino propyl cartridge. Deter mination is by gas chromatography with mass-selective detection in the sele cted-ion monitoring mode, and by liquid chromatography with post-column rea ction and fluorescence detection for N-methyl carbamates. The method has be en used for analysis of various fruits and vegetables, such as apple, banan a, cabbage, carrot, cucumber, lettuce, orange, pear, pepper, and pineapple. Limits of detection range between 0.02 and 1.0 mg/kg for most compounds. O ver 80% of the compounds have a limit of detection of less than or equal to 0.04 mg/kg.