Abstract: A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the extraction of 14 phthalate esters (PAEs) in barley prior to gas chromatography-mass spectrometry (GC-MS) analysis. All barley samples were smashed, sieved with an 80-mesh siever and dissolved in an aqueous solution at pH 2. The PAEs in samples were extracted with acetonitrile and salted out with anhydrous MgSO4 and NaCl. Then, after centrifugation, the supernatant was cleaned up with a C18 sorbent at a solid-to-liquid ratio of 50 mg/g. Moreover, the addition after extraction method was used to evaluate the matrix effects (ME) in the GC-MS analysis of 14 PAEs. As a result, all 14 PAEs exhibited an enhanced matrix effect in barley matrix, with a percentage enhancement in the range of 41.0% to 78.1%. Thus, a matrix-matched curve could be used to eliminate the matrix effects and in turn achieve more accurate quantitation. The recoveries of 14 PAEs in barley matrixes at three spiked levels of 15, 150 and 500 μg/kg ranged from 73.8% to 120.1% with relative standard deviations (RSD) below 10%. The limits of detection (LODs) and limits of quantitation (LOQs) for the PAEs, based on RSN ratio of 3 and 10, ranged from 0.1 to 2.5 μg/kg and from 0.13 to 5.0 μg/kg, respectively. Finally, the 14 PAEs in six barley samples were successfully determined using the proposed method. The results indicated that dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), and bis(2-methoxyethyl) phthalate (DEHP) were present in all the samples examined, but their concentrations were different. The contents of DEP and DEHP detected in all the barley samples were below the maximum residue limit stipulated in the Chinese National Standard (GB 9685—2008).

Key words: barley, QuEChERS, phthalate esters (PAEs), gas chromatography-mass spectrometry (GC-MS), matrix effect