Rapid Determination of Pesticide Residues in Herbs Using Selective Pressurized Liquid Extraction and Fast Gas Chromatography Coupled with Mass Spectrometry
Institute of Chinese Medical Sciences, University of Macau, Taipa, Macao SAR, China. Journal of Separation Science
(Impact Factor: 2.74).
08/2012; 35(15):1922-32. DOI: 10.1002/jssc.201200169
A selective pressurized liquid extraction and gas chromatography coupled with triple quadrupole mass spectrometer method was developed for simultaneous determination of 52 pesticide residues in medicine and food dual-purpose herbs. The developed extraction method integrated extraction and cleanup processes for sample preparation. The sorbents, 5 g Florisil and 100 mg graphitized carbon black, were placed inside the extraction cell to remove matrix interferences. Optimized conditions of selective pressurized liquid extraction were ethyl acetate as extraction solvent, 120°C of extraction temperature, 6 min of static extraction time, 50% of flush volume extracted for two cycles. An ultra inert capillary GC-MS HP-5 UI column (20 m × 0.18 mm id, 0.18 μm) and column backflush system were used for the analysis. Multiple-reaction monitoring was employed for the quantitative analysis with electron ionization mode. All calibration curves showed good linearity (r(2) > 0.995) within the test ranges. The average recoveries of most pesticides were from 81 to 118%. The validated method was successfully applied for the determination of pesticide residues in four herbs. The results indicate that selective pressurized liquid extraction and GC-MS/MS is a sensitive and reliable analytical method for the simultaneous determination of multiple pesticide residues in herbs.
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- "GC × GC is considered an established separation technique and for the last decade focus has shifted away from the development of modulation technology to applying the technique to an ever increasing number of analytical challenges. Fields in which GC × GC applications are popular include petroleum and petrochemicals           ; food, flavours and fragrances              ; metabolomics             and environmental analysis       . Although GC × GC has never been more widespread, there are some applications that remain challenging for a chromatographer to perfect. "
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ABSTRACT: Comprehensive two-dimensional gas chromatography (GC×GC) is recognised as a powerful tool for the separation of complex mixtures of volatile and semi-volatile compounds. In the analysis of challenging samples containing highly concentrated, active analytes or those with complicated matrices, it is often the case that less than ideal chromatography is produced. GC×GC chromatograms of such samples typically contain broad, tailing analyte bands. This results in difficulties with quantitation and poor utilisation of the separation space. In this study we investigated the inlet and the modulator as the potential sources of these tailing bands. A simple inlet backflushing device was developed to isolate the inlet from the primary column after the injection, and a similar setup was used to isolate the modulator from the primary column. The device allowed us to divert carrier gas flow back through the inlet at a specified time after the injection, while allowing analytes to pass through the column for separation. Analytes retained within the inlet were prevented from entering the column, and were subsequently removed via the carrier gas split line. The study revealed that the inlet plays a significant role in the development of tailing chromatographic bands, while the modulator simply modulates the already elongated band. Inlet backflushing is a cheap, simple and effective tool that can be used to improve the chromatography of problematic GC×GC analyses of samples consisting of concentrated and active analytes, those derived from natural products and containing complicated matrices.
Copyright © 2015 Elsevier B.V. All rights reserved.
Journal of Chromatography A 05/2015; 1402. DOI:10.1016/j.chroma.2015.05.014 · 4.17 Impact Factor
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ABSTRACT: This review updates our knowledge on pressurised liquid extraction, PLE (also known as accelerated solvent extraction and pressurised fluid extraction) of persistent organic pollutants such as polynuclear aromatic hydrocarbons and polychlorinated biphenyls from environmental matrices. The basic experimental set-up is presented, and parameters influencing the extraction process are discussed. PLE can be used for a broad range of applications, and clearly has the potential for replacing tedious classic extraction methods such as Soxhlet extraction.
TrAC Trends in Analytical Chemistry 07/2000; 19(7-19):434-445. DOI:10.1016/S0165-9936(00)00002-9 · 6.47 Impact Factor
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ABSTRACT: Pre-column back-flushing is a matrix minimization technique in GC in which the carrier gas flow of the pre-column is reversed after the transfer of the highest boiling analyte to the analytical column. Practical details concerning this technology have rarely been published although it is widely used. This paper now-focuses on the practical implementation of pre-column back-flushing for pesticide residue analysis of complex food matrices. Fitting the analytical column into the pre-column was found to be essential for comparable analyte responses with and without back-flushing. The effectiveness of the reverse column flow technique is mainly affected by the transfer time after which back-flushing starts. The transfer time was found to depend on which kind of injected matrix is used and the state of the pre-column. For the regular adaptation of the transfer time in routine analysis, a simple test was introduced in which 13-C-labeled deltamethrin and indeno[1,2,3-c,d]pyrene were added to the prepared extract. Chromatograms, limits of quantification and relative standard deviations of up to 99 pesticides in citrus oil and liver extracts proved a clearer identification and enhanced quantification using pre-column back-flushing compared to measurements without this technology. Furthermore, reduced system maintenance could be achieved through back-flushing. This article is protected by copyright. All rights reserved.
Journal of Separation Science 07/2013; 36(13). DOI:10.1002/jssc.201300007 · 2.74 Impact Factor
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