Determination of 6 Phthalate Esters in Plastic Express Package by Gas Chromatography-Mass Spectrometry with Ultrasonic Extraction

In view of the problems of complex operation, long time consuming and expensive equipment in the pretreatment methods adopted by current standards, ultrasonic extraction technology, which was easy to implement, was selected. The effects of different extraction conditions on the extraction effect of phthalate esters (PAEs) in the quality control sample was investigated, and a method for the determination of 6 PAEs, including dibutyl phthalated (DBP), butyl benzyl phthalate (BBP), bis (2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), di-iso-nonyl phthalate (DINP) and di-iso-decyl phthalate (DIDP) in plastic express package by gas chromatography-mass spectrometry with ultrasonic extraction was proposed. The plastic package sample was cut into small pieces, and 0.5 g of an aliquot and 20 mL of methylene chloride were added into a glass extraction bottle, and ultrasonic extraction was performed for 30 min at 25℃. The supernatant was filtered by 0.45 μm organic filter membrane, and a certain amount of dipentyl phthalate (internal standard) solution was added to make its mass concentration to 5.0 mg·L^-1. The 6 PAEs were separated on DB-5MS capillary column with column temperature program, detected by mass spectrometer equipped with electron impact ionization and full scanning mode, and quantified by internal standard method. It was shown that the linear ranges of standard curves of 6 PAEs were 0.10-5.0 mg·L^-1 (DBP, BBP, DEHP and DNOP) and 1.0-50 mg·L^-1 (DINP and DIDP), with detection limits (3S/N) in the range of 0.03-0.63 mg·kg^-1. Test for recovery was made on blank sample by addition standard method, giving results of 6 PAEs in the range of 92.2%-105%, and RSDs (n=6) of the determined values were ranged from 0.76% to 3.2%. This method was applied to the analysis of 10 plastic express package samples, DBP and DEHP were detected in two samples, and the targets were not detected in the other samples. The effects of ultrasonic extraction method, Soxhlet extraction method (GB/T 22048-2015) and microwave digestion method (SN/T 2249-2009) on the determined results of the quality control sample and actual samples were compared, and the determined results of the quality control sample were within the uncertainty ranges of the certified values. DBP and DEHP were detected in 3 actual samples, the targets were not detected in the other samples, and the results obtained by the 3 pretreatment methods were similar.