Multiresidue analysis of pesticides in foods using liquid chromatography/mass spectrometry

We developed a multiresidue method (MRM) using LC/MS which enabled to analyze 50 thermolabile or involatile pesticides in foods because of remaining unavailable for the GC mehod. The sample wasa extracted with acetonitrile. After a salting-out with sodium chloride, the acetonitrile extract was 'purified by gel permeation chromatography. The pesticide fraction was purifeied by ENVI-Carb/NH2 column and determined by LC/MS. Apples, grapefruits, Japanese radishes, brown rice, spinach, and green tea were used for recovery tests in triplicates. The recoveries were more than 70% in 81% (264/324) of the tested items. The complemental use of this method for the conventional GC/MS methods would enable analysis of a wide range of pesticides in a large number of crops.