Determination of 19 phthalate esters in cucumbers using QuEChERS coupled with gas chromatography-triple quadrupole mass spectrometry

Abstract

An efficient method using QuEChERS equipped with triple quadrupole GC-MS/MS for the simultaneous detection of 19 phthalate acid ester residues in cucumbers was established. The phthalate acid esters were extracted from cucumber samples by ultrasonic with acetonitrile. The extracts were salted out and centrifuged with anhydrous magnesium sulfate and sodium chloride. The supernatants were enriched by vacuum distillation, and then purified by C18 adsorbent. The 19 phthalate esters were separated on an HP-5ms UI column (30 mx 0.25 mm x 0.25 μm), and determined using MS/MS in multiple reactions monitoring mode. The method showed favorable qualitative and quantitative analysis of the phthalate esters with good linearity (r ≥ 0.9995) in the linear range of 10-5,000 μg/kg and the limits of detection (LODs) were 0.2-3.5 μg/kg. With the proposed method, the recoveries were evaluated in cucumbers at the spiked levels of 10, 100 and 500 μg/kg. The results showed that the average recoveries were ranged from 63.3%-127.8% and the relative standard deviations (RSDs) were 0.5%-13.3%. In short, the proposed method with high sensitivity and good accuracy can meet the determination requirements for multi-residues. Furthermore, the method can be applied for the simultaneous determination of phthalate acid esters in cucumbers.