Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2010
Publication Date: 10/1/2010
Citation: Koesukwiwat, U., Lehotay, S.J., Miao, S., Leepipatpiboon, N. 2010. High throughput analysis of 150 pesticides in fruits and vegetables using QuEChERS and low-pressure gas chromatography – time-of-flight. Journal of Chromatography A. 1217:6692-6703. Interpretive Summary: For monitoring purposes, a wide range of pesticide residues in numerous food commodities are routinely analyzed in many regulatory and private contract laboratories worldwide. A higher monitoring rate is highly desirable in the labs, but this goal is typically limited by the number of samples that a lab can analyze in a given time (i.e., sample throughput). In this study, sample throughput was more than doubled vs. current lab methods by using a fast and robust approach that still achieves wide monitoring scope and high quality results for many pesticide residues in different foods. Based on this study, more labs are expected to use this novel approach to increase sample throughput and the monitoring rate. Also, fresh foods that are tested for pesticide residues will reach the market sooner because analytical results will be obtained faster.
Technical Abstract: In this study, we sought to assess the real-world applicability of fast, low-pressure gas chromatography - time-of-flight mass spectrometry (LP-GC/TOFMS) for the identification and quantification of 150 pesticides in tomato, strawberry, potato, orange, and lettuce samples. Buffered and unbuffered versions of QuEChERS using dispersive solid-phase extraction (d-SPE) and disposable pipette extraction (DPX) for cleanup were compared for sample preparation. For clean-up of all sample types, a combination of 150 mg magnesium sulfate, 50 mg primary secondary amino (PSA), 50 mg C-18, and 7.5 mg graphitized carbon black (GCB) per mL extract was used. No significant differences were observed in the results between the different sample preparation versions. QuEChERS took <10 min per individual sample, or <1 hr for 2 chemists to prepare 32 pre-homogenized samples, and using LP-GC/TOFMS, <10 min run time and <15 min cycle time allowed >32 injections in 8 hrs. Overall, >126 analytes gave recoveries (3 spiking levels) in the range of 70-120% with <20% RSD. The results indicate that LP-GC/TOFMS for GC-amenable analytes matches current fast liquid chromatography – tandem mass spectrometry methods in terms of sample throughput and turnaround time for their routine, concurrent use in the analysis of a wide range of analytes in QuEChERS extracts to achieve reliable quantification and identification of pesticide residues in foods.