[Determination of 23 phthalate esters in scallion and other vegetables by solid-phase extraction coupled with gas...

A method for the simultaneous determination of 23 phthalate esters in vegetables by solid-phase extraction coupled with gas chromatography-triple quadrupole mass spectrometry (SPE-GC-MS/MS) was developed and evaluated. The samples were extracted with acetonitrile, and cleaned-up with glass Florisil SPE columns, and diluted with n-hexane. The separation was performed on a DB-5MS UI capillary column (30 m x 0.25 mm x 0.25 µm) with temperature programming. The identification and quantification were performed by GC-MS/MS in selected reaction monitoring (SRM) mode. The external standard method was used. The processes of extraction and clean-up of scallion and other vegetables were investigated, and the chromatographic and MS parameters were optimized. The matrix effect was compensated by matrix spiked calibration. The extraction processes were investigated. The calibration curves of the phthalate esters showed good linearities in the ranges of 0.02-1 mg/L (0.1-5 mg/L for diisononyl phthalate (DINP) and diisodecyl-o-phthalate (DIDP)) with the correlation coefficients (r) over 0.99 except for bis(2-methoxyethyl) phthalate (DMEP). The limits of detection of phthalate esters in samples ranged from 0.01 to 0.05 mg/kg (S/N = 3) and the limits of quantification ranged from 0.02 to 0.1 mg/kg (S/N = 10). The average recoveries of the 23 analytes spiked in scallions ranged from 81.3% to 104.2% with the relative standard deviations (RSDs, n = 6) of 3.2%-11.2%. The method is suitable for the determination of the 23 phthalate esters simultaneously in vegetables with easy operation, high accuracy and precision.