Submitted to: Journal of Chromatography A
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/12/2004
Publication Date: 9/15/2004
Citation: Mastovska, K., Hajslova, J., Lehotay, S.J. 2004. Ruggedness and other performance characteristics of low-pressure gas chromatography-mass spectrometry for the fast analysis of multiple pesticide residues in food crops. Journal of Chromatography A. 1054. 2004. p. 335-349. Interpretive Summary: Current methods of analysis for pesticide residues and other chemical contaminants in food are time-consuming. Low-pressure gas chromatography/mass spectrometry (LP-GC/MS) is an unique approach to speed the analysis of many types of chemical residues, including pesticides. In this study, a comparison was made between a wider analytical column of thicker film versus a narrower column of thinner film in LP-GC/MS. The narrower column configuration in this study gave a slightly faster separation of the pesticides, but the wider analytical column with a thicker film gave and greater sensitivity and ruggedness. The analysis of 57 pesticides was optimized and demonstrated using LP-GC/MS with separation time less than 6 min, which is 5-7 times faster than traditional methods of analysis. This form of fast-GC/MS approach shows promise to become a widely used tool to help increase sample throughput in the analysis of pesticide residues.
Technical Abstract: Low-pressure gas chromatography-mass spectrometry (LP-GC-MS) using a quadrupole MS instrument was further optimized and evaluated for the fast analysis of multiple pesticide residues in food crops. Performance of two different LP-GC-MS column configurations was compared in various experiments, including thorough ruggedness tests with repeated injections of pesticides in matrix extracts. The tested column configurations employed the same 3 m x 0.15 mm i.d. restriction capillary at the inlet end, but different analytical columns attached to the vacuum: (A) 10 m x 0.53 mm i.d., 1 mm film thickness capillary column, and (B) 10 m x 0.25 mm i.d., 0.25 mm film thickness column. Under the optimized conditions (compromise between speed and sensitivity), the narrower analytical column with a thinner film provided slightly (< 1.1-fold) faster analysis of < 5.5 min separation times and somewhat greater separation efficiency. However, lower detection limits for most of the tested pesticides in real extracts were achieved using the mega-bore configuration, which also provided significantly greater ruggedness of the analysis. Additionally, the effect of the increasing injection volume on analyte signal to noise ratios was also evaluated. For the majority of the tested analyte-matrix combinations, the increase in sensitivity caused by a larger injection did not translate into the same gain in analyte detectability. Considering the costs and benefits, the injection volume of 2-3 microliters was optimal for detectability of the majority of 57 selected pesticides in apple, carrot, lettuce, and wheat extracts.