Residue analysis of kresoxim-methyl and boscalid in fruits, vegetables and soil using liquid-liquid extraction and gas chromatography-mass spectrometry.

A GC-MS procedure for simultaneously determining and validating kresoxim-methyl and boscalid has been developed in fruit, vegetable and soil matrices. The method was based on one-step liquid-liquid extraction with acetone and dichloromethane solvents. Estimated limits of detection (LODs) for kresoxim-methyl and boscalid were 0.006 and 0.015 mg/kg, and limits of quantification (LOQs) were 0.02 and 0.05 mg/kg, respectively. The intra- and inter- precision were achieved with RSD better than 13.8 and 14.5%, and recoveries were in the range of 77.1-98.7% for kresoxim-methyl and 72.8-105.1% for boscalid. The expanded uncertainties calculated at 0.1 mg/kg were below 18%. Concentration levels for residues of the two fungicides in melon samples from field trials collected 7 days after the last application were clearly below the established MRL values.