Application of Isotope Dilution Gas Chromatography-Mass Spectrometry in Analysis of Organochlorine Pesticide Residues in Ginseng Root
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- 作者：Serena Chan ; Mei-Fong Kong ; Yiu-Chung Wong ; Siu-Kay Wong ; Della W. M. Sin
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2007
- 出版时间：May 2, 2007
- 年：2007
- 卷：55
- 期：9
- 页码：3339 - 3345
- 全文大小：101K
- 年卷期：v.55,no.9(May 2, 2007)
- ISSN：1520-5118
文摘
A highly accurate and precise method based on isotope dilution gas chromatography-massspectrometry was developed for the determination of five matrix-bound organochlorine pesticides,namely, hexachlorobenzene and hexachlorocyclohexanes (
-, 
-, 
-, and 
- isomers), in a referencesample of Panax gingseng. Identification of the analytes was confirmed under selective ion monitoringmode by the presence of two dominant ion fragments within the specific time windows (±1% of therelative retention time with respect to the calibration standards) and matching of relative ion intensitiesof the concerned ions in samples and calibration standards (within ±5%). Quantification was basedon the measurement of concentration ratios of the natural and isotopic analogues in the sample andcalibration blends. To circumvent the tedious iterative process of exact isotope matching that is oftenused in isotope dilution mass spectrometry analysis, a single-point calibration procedure was adoptedwith the isotopic amount ratios in the sample and calibration blends close to unity (0.9-1.1). Underthe described approach, intraday and interday repeatability of replicate analyses of organochlorinepesticides in the ginseng root sample were below 1.4%. The expanded relative uncertainty rangingfrom 4.0 to 6.5% at a coverage factor of 2 was significantly lower than those of conventional gaschromatographic methods using other calibration techniques (internal or external standards). Adeviation of less than 2.0% from the certified values was achieved when applying the developedmethod to determine hexachlorobenzene, -, and -hexachlorocyclohexane in a certified referencematerial (CRM), BCR-CRM 115. Because of the unavailability of relevant CRMs of herbal origins,the concerned ginseng root sample, after verification of the "true values" of the concernedorganochlorine pesticides by the valid primary method, is suitable for serving as an in-house referencematerial for quality assurance and method validation purposes.
-, -, -, and - isomers), in a referencesample of Panax gingseng. Identification of the analytes was confirmed under selective ion monitoringmode by the presence of two dominant ion fragments within the specific time windows (±1% of therelative retention time with respect to the calibration standards) and matching of relative ion intensitiesof the concerned ions in samples and calibration standards (within ±5%). Quantification was basedon the measurement of concentration ratios of the natural and isotopic analogues in the sample andcalibration blends. To circumvent the tedious iterative process of exact isotope matching that is oftenused in isotope dilution mass spectrometry analysis, a single-point calibration procedure was adoptedwith the isotopic amount ratios in the sample and calibration blends close to unity (0.9-1.1). Underthe described approach, intraday and interday repeatability of replicate analyses of organochlorinepesticides in the ginseng root sample were below 1.4%. The expanded relative uncertainty rangingfrom 4.0 to 6.5% at a coverage factor of 2 was significantly lower than those of conventional gaschromatographic methods using other calibration techniques (internal or external standards). Adeviation of less than 2.0% from the certified values was achieved when applying the developedmethod to determine hexachlorobenzene, -, and -hexachlorocyclohexane in a certified referencematerial (CRM), BCR-CRM 115. Because of the unavailability of relevant CRMs of herbal origins,the concerned ginseng root sample, after verification of the "true values" of the concernedorganochlorine pesticides by the valid primary method, is suitable for serving as an in-house referencematerial for quality assurance and method validation purposes.