Enhanced signal generation for use in the analysis of synthetic pyrethroids using chemical ionization tandem quadrupole ion trap mass spectrometry

GC-MS determination of targeted pesticides in environmental samples from the Kafue Flats of Zambia

Results of a GC-MS analysis for targeted pesticides i.e. dieldrin, endosulfan, pp-DDT, endrin, HCB, heptachlor, mirex and aldrin in the Kafue Flats of Zambia are presented. Analysis was done in soils, sediments, water and vegetation samples from the Lochinvar and Blue Lagoon National Parks along the Kafue River. A validated analytical method that was used gave recoveries in a spiked soil sample ranging between 60 % and 100 % with limits of detection (LODs) ranging from 0.94 to 8.0 ng/g. The targeted pesticides were not detected in all the samples i.e. were below LODs. Screening using the Automated Mass Spectral Deconvolution and Identification System (AMDIS) simplified the analysis due to its power of deconvolution and identification of analytes of interest.

Development of an analytical scheme for the determination of pyrethroid pesticides in composite diet samples

Analysis of an individual's total daily food intake may be used to determine aggregate dietary ingestion of given compounds. However, the resulting composite sample represents a complex mixture, and measurement of such can often prove to be difficult. In this work, an analytical scheme was developed for the determination of 12 select pyrethroid pesticides in dietary samples. In the first phase of the study, several cleanup steps were investigated for their effectiveness in removing interferences in samples with a range of fat content (1-10%). Food samples were homogenized in the laboratory, and preparatory techniques were evaluated through recoveries from fortified samples. The selected final procedure consisted of a lyophilization step prior to sample extraction. A sequential 2-fold cleanup procedure of the extract included diatomaceous earth for removal of lipid components followed with a combination of deactivated alumina and C(18) for the simultaneous removal of polar and nonpolar interferences. Recoveries from fortified composite diet samples (10 microg kg(-1)) ranged from 50.2 to 147%. In the second phase of this work, three instrumental techniques [gas chromatography-microelectron capture detection (GC-microECD), GC-quadrupole mass spectrometry (GC-quadrupole-MS), and GC-ion trap-MS/MS] were compared for greatest sensitivity. GC-quadrupole-MS operated in selective ion monitoring (SIM) mode proved to be most sensitive, yielding method detection limits of approximately 1 microg kg(-1). The developed extraction/instrumental scheme was applied to samples collected in an exposure measurement field study. The samples were fortified and analyte recoveries were acceptable (75.9-125%); however, compounds coextracted from the food matrix prevented quantitation of four of the pyrethroid analytes in two of the samples considered.