Determination of Chlorpyrifos Residues in Cherry Samples by Direct Immersion Solid Phase Microextraction Coupled with Gas Chromatography Mass Spectrometry

A method based on a solid phase microextraction gas chromatography- mass spectrometry (SPME-GC/MS) was developed for the quantitative determination of chlorpyrifos residues in cherry samples. Three kinds of fiber coatings: PA (polyacrylate, 85µm), PDMS–DVB (polydimethylsiloxane–divinylbenzene 65 mm) and PDMS (polydimethylsiloxane, 100 mm) were compared. Various parameters affecting SPME procedures such as temperature, extraction and desorption times, salinity, stirring rate were investigated. The analytes from all sample extracts were preconcentrated for 30 minutes in the SPME fiber at 60 °C and then the fiber was desorbed by heating at 250 °C for 10 minutes in the gas chromatography injection port. Limits of detection (LOD) and quantitation (LOQ) values were 0.03 µg/L and 0,1 µg/L, respectively. An average recovery range was 93-98% with relative standard deviation (RSD) < 10 %.