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Optimization of a multi‐residue screening method for the determination of 85 pesticides in selected food matrices by stir bar sorptive extraction and thermal desorption GC‐MS
Author(s) -
Ochiai Nobuo,
Sasamoto Kikuo,
Kanda Hirooki,
Yamagami Takashi,
David Frank,
Tienpont Bart,
Sandra Pat
Publication year - 2005
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200500017
Subject(s) - chromatography , thermal desorption , chemistry , detection limit , pesticide , extraction (chemistry) , pesticide residue , desorption , methanol , adsorption , matrix (chemical analysis) , gas chromatography , residue (chemistry) , analytical chemistry (journal) , biochemistry , organic chemistry , agronomy , biology
A multi‐residue method to determine 85 pesticides, including organochlorine pesticides, carbamates, organophosphorus pesticides, and pyrethroids, in vegetables, fruit, and green tea, has been developed. The method is based on stir bar sorptive extraction (SBSE) coupled to thermal desorption (TD) and retention time locked (RTL) GC‐MS operating in the scan mode. Samples are extracted with methanol and diluted with water prior to SBSE. Dilution of the methanol extract before SBSE was optimized to obtain high sensitivity and to minimize adsorption onto the glass wall of the extraction vessel as well as to minimize sample matrix effects (particularly for the pesticides with high log K o/w values). The optimized method consists of a dual SBSE extraction performed simultaneously on respectively a twofold and a fivefold diluted methanol extract. After extraction, the two stir bars are placed in a single glass thermal desorption liner and are simultaneously desorbed. The method showed good linearity ( r 2 > 0.9900) and high sensitivity (limit of detection: < 5 μg kg –1 ) for most of the target pesticides. The method was applied to the determination of pesticides at low μg kg –1 in tomato, cucumber, green soybeans, spinach, grapes, and green tea.