Analysis of multiple pesticide residues in rice by LC-MS/MS

A multiresidue method without cleanup step was validated for simultaneous determination of multiclass pesticide residues in rice. The extracted incurred residues of pesticides were separated on a reversed-phase column and quantified by tandem mass spectrometry (MS/MS). The method accuracy was in the range of 71-108%, and the precision was in the range of 4-20% for 25 out of 28 selected pesticides. The method quantification limits for 25 selected pesticides were below Codex and EU maximum residue limits (MRL). The selected 25 pesticides met the EU-SANTE and FAO/WHO Codex Alimentarius Commission method validation guidelines. The interday repeatability of the optimized method was between 4 and 18% (n = 6). The expanded uncertainty calculated for the optimized method ranged from 22 to 48%. The results obtained demonstrated the method's suitability for routine analysis. In total, 35 samples were analyzed of which, 22 samples (62%) were found to be contaminated with pesticides concentrations ranging from 0.010 to 0.297 mgkg(-1).