Simultaneous determination of 18 preservative residues in vegetables by ultra high performance liquid chromatography coupled with triple quadrupole/linear ion trap mass spectrometry using a dispersive-SPE procedure.

A new method combining dispersive-solid phase purification procedure with ultra high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry was developed for simultaneous determination of 18 preservative residues in vegetables. The new method not only had the advantages of dispersive-solid phase purification procedure such as high recoveries, easy operation, rapid analysis, little solvent usage and wide analysis range of preservatives, but also had the advantages of ultra high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry to be operated in positive mode and negative mode simultaneously. The method was validated for the following representative matrices: radish (tuber), tomato (eggplant fruit), cabbage (leafy), cowpea (bean), cucumber (melon) and so on. Samples were extracted with hexane-ethyl acetate (1:2, v/v), and then detected by ultra high performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry after being cleaned up with dispersive-solid phase purification procedure. Significant matrix effects were compensated by using the matrix-matched calibration curves. 18 preservatives showed good linearity over the range of 5.0-100.0 μg/L with correlation coefficients of 0.9904-1.000. The limits of detections were in the range of 0.04-4.16 μg/kg and the limits of quantity were in the range of 0.13-13.85 μg/kg. The recoveries of 18 preservatives ranged from 76.0% to 120.0% with the spiked levels of 2, 4 and 10 μg/kg into homogenized vegetables, and the relative standard deviations (RSDs) ranged from 0.3% to 14.8%. Compared with the reported literatures, the method is more rapid, simple, highly sensitive, reliable and can meet testing requirements of 18 preservative residues in vegetables.