Analysis of triallate residues in cereals and soil by gas chromatography with ion-trap detection.
Triallate residues in barley seedlings and soil samples were determined by gas chromatography with ion-trap detection. Soil was extracted with methanol on a mechanical shaker, and plants were extracted with acetonitrile in a Sorvall homogenizer. After evaporation of the organic solvents, the residue was dissolved in hexane, and plants extracts were cleaned-up on an alumina column. Gas chromatographic analysis was carried out using a BP-1 fused-silica capillary column with helium as carrier gas. To quantitate residues the total-ion chromatogram was obtained and then the selected-ion monitoring chromatograms were displayed at m/z 86 for triallate and at m/z 154 for the internal standard, methyl-(4-amino-2-chloro)-benzoate. The average recovery through the method from barley and soil samples was always higher than 80%. The limit of detection in the selected-ion mode was 0.01 mg/kg. Barley and soil samples treated with triallate were also analysed. A good agreement was observed between results obtained by this method and by gas chromatography with nitrogen-phosphorus detection.
Application of capillary gas chromatography with mass selective detection to pesticide residue analysis
Abstract A random sample of 76 pesticides with good gas chromatographic properties has been collected in order to test the applicability of the mass selective detector HP MSD for pesticide residue analysis. Using a capillary column, mass spectra of good quality were produced with 10 or 20 ng of each pesticide. Seventy two compounds were not only identified at this concentration with the PBM (probability based matching) search routine in the NBS library, but also remarkably with the best fit in the corresponding hit list. Lower concentrations can be detected only with selected ion monitoring (SIM). A mixture of 18 chlorinated pesticides was added to green pepper at the 10 ppb level. All compounds were detected with SIM using special time programming in one gas chromatogaphic analysis. The detection sensitivity of the mass selective detector in SIM mode approaches that of established selective detectors. The reliability of the results with respect to the identity of a pesticide residue, however, is orders of magnitude better. Therefore, this detector is a valuable tool for performing confirmatory analysis.
Uptake and Translocation of Diallate in Wheat, Barley, Flax, and Wild Oat
Uptake and translocation of 14C label from S-2,3-dichloroallyl N,N-diisopropylthiolcarbamate (diallate) by roots and coleoptiles of wild oat (Avena fatua L.), wheat (Triticum aestivum L., var. Selkirk), barley (Hordeum vulgare L., var. Traill), and flax (Linum usitatissimum L., var. Bolley) were compared. The pattern of 14C label uptake and movement was similar in wild oat, barley, and wheat. However, translocation of the 14C label to the roots of wild oat was less than for barley. Although differential uptake and translocation per se did not appear to account for the selectivity of diallate for wild oat, some differences in translocation may have beep the result of metabolic breakdown products.