Analysis of currently used pesticides in fine airborne particulate matter (PM 2.5) by pressurized liquid extraction and liquid chromatography–tandem mass spectrometry

During and after the application of currently used pesticides (CUPs) a significant fraction of applied pesticides can be lost to the air. A confirmatory and rapid procedure has been developed for the determination of four fungicides (carbendazim, thiabendazol, imazalil and bitertanol), three insecticides (imidacloprid, methidathion and pyriproxyfen), one helicide (methiocarb) and one acaricide (hexythiazox) in fine airborne particulate matter (PM 2.5) at trace level. The proposed method includes extraction of PM 2.5-bound pesticides by pressurized liquid extraction (PLE) followed by a direct injection into LC–MS/MS. The main parameters affecting the performance of the electrospray ionization source and PLE parameters were optimised using statistical design of experiments (DoE). The matrix effect was also evaluated. Recoveries ranged from 86 to 106% and the limit of quantification (LoQ) was 6.5 pg m−3 for eight out of nine pesticides, when air volumes of 760 m3 were collected. The method was applied to 60 samples collected from four stations of the monitoring network of the Regional Valencia Government (Spain) during August–October 2007. The measured concentrations ranged from not detected to 1371 pg m−3.