MULTIRESIDUE PESTICIDE ANALYSIS BY ION-TRAP TECHNOLOGY - A CLEANUP APPROACH FOR MASS-SPECTRAL ANALYSIS

Previous studies using the ion trap as a potential replacement for an array of element-sensitive detectors indicated that only semi-quantitative results at the 50-100 ppb range could be obtained for 245 pesticides because of interfering endogenous sample matrix-compounds. The development of a new clean-up procedure for a wide range or fruits and vegetables, specifically for use in an ion trap, has been undertaken to improve recoveries at the low ppm level to within analytically acceptable ranges (80-120%). This clean-up involved the use of three solid-phase extractions. The use of a C-18 SepPak column removed the majority of hydrocarbon-like molecules while the anion-exchange column (QMA) removed all colored compounds and flavors, and finally the use of an aminopropyl column removed all sugars. Preliminary results from this study using 24 selected pesticides in four different sample matrices have indicated an acceptable improvement over previous results.