Determination of combined residues of metalaxyl and 2,6-dimethylaniline metabolites in urine by gas chromatography/mass spectrometry.

A gas chromatographic/mass spectrometric (GC/MS) method for determination of combined residues of the fungicide metalaxyl and its metabolites in urine containing the 2,6-dimethylaniline moiety is described. The method is a modification of a method of Balasubramanian and Perez for analysis of metalaxyl in vegetables. Noted modifications include replacement of steam extraction with extraction by methylene chloride and use of electron impact ionization GC/MS in the selected-ion mode. The method is linear over the range of 0.1-5 micrograms 2,6-dimethylaniline/g urine and has a detection limit of 0.025 microgram/g.