How to overcome matrix effects in the determination of pesticides in fruitby HPLC-ESI-MS-MS

A high-performance liquid chromatographic method, with electrospray ionisat ion tandem mass spectrometry (HPLC-ESI-MS-MS) for detection, has been devel oped for the determination of thiabendazole, carbendazime, and phenylurea p esticides in fruit matrices. During the validation process the method was t ested for matrix effects, blanks, and the stability of the system. Consider able unspecific matrix effects in the ESI (+) process were detected by comp aring standard calibration, and matrix calibration, although blank values w ere very low and the specific calibration functions showed only small stand ard deviations. This effect was overcome by using a more complex clean-up, i.e. an additional size-exclusion step.