Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2011
Publication Date: 8/6/2011
Citation: Koesukwiwat, U., Lehotay, S.J., Leepipatpiboon, N. 2011. Fast,low-pressure gas chromatography triple quadrupole tandem mass spectrometry for analysis of 150 pesticide residues in fruits and vegetables. Journal of Chromatography. 1218:7039-7050. Interpretive Summary: In regulatory and contract laboratories worldwide, a wide range of pesticide residues in numerous food commodities are routinely analyzed to ensure food safety and meet international trade laws. There is a continual need for faster, easier, and less expensive ways to achieve a wide monitoring scope and high quality analytical results. In this study, a state-of-the-art approach is developed and validated for 150 pesticides in four representative fruit and vegetable commodities. The method uses the latest version of the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method for sample preparation and an advantageous gas chromatographic tandem mass spectrometric detection method to quantify and identify the targeted residues in fruits and vegetable samples below the regulatory limits. An outcome of this study will be faster and better routine monitoring of pesticide residues for international trade and food safety purposes.
Technical Abstract: We developed and evaluated a new method of low-pressure gas chromatography-tandem mass spectrometry (LP-GC/MS-MS) for fast analysis of 150 pesticides in four representative fruits and vegetables. This LP-GC (vacuum outlet) approach entails coupling a 10 m, 0.53 mm i.d., 1 micron film analytical column between the MS transfer line and a 3 m, 0.15 mm i.d. capillary at the inlet. The MS creates a vacuum in the 10 m analytical column, which reduces the viscosity of the He carrier gas and thereby shifts the optimal flow rate to greater velocity. By taking advantage of the hydrogen-like properties of helium under vacuum, the short analytical column, a rapid oven temperature ramp rate, and the high selectivity and sensitivity of MS/MS, 150 pesticides were separated in <6.5 min. The 2.5 ms dwell time and 1 ms interscan delay of the MS/MS instrument were critical for achieving >8 data points across the 2-3 s wide peaks. To keep dwell and cycle times constant across all peaks, each segment consisted of 30 analytes (60 transitions). For assessment, we injected extracts of spiked broccoli, cantaloupe, lemon, and sweet potato from the updated QuEChERS sample preparation method. Average recoveries (n = 72) were 70-120% for 144 of the pesticides, and reproducibilities were <20% RSD for all but 4 analytes. Also, detection limits were <5 ng/g for all but a few pesticides. In addition to high quality performance, the method gave excellent reliability and high sample throughput, including easy peak integration to obtain rapid results.