Simultaneous screening of 33 restricted substances in polymer materials using pyrolysis/thermal desorption gas chromatography-mass spectrometry

摘要

The purpose of this study was to offer a quick and efficient method to screen for multiple restricted additives in polymer materials. A solvent-free pyrolysis gas chromatography-mass spectrometry method was developed to simultaneously screen 33 restricted substances, comprising 7 phthalates, 15 bromine flame retardants, 4 phosphorus flame retardants, 4 ultraviolet stabilizers, and 3 bisphenols. The pyrolysis technique and temperatures affecting additive desorption were studied. Under optimized conditions, the instrument sensitivity was confirmed using in-house reference materials at concentrations of 100 mg/kg and 300 mg/kg. The linear range was between 100 and 1000 mg/kg in 26 compounds, and in the other compounds it was between 300 and 1000 mg/kg. In this study, in-house reference materials, certified reference materials, and proficiency testing samples were used for method verification. The relative standard deviation of this method was less than 15%, and recoveries ranged from 75.9 to 107.1% for most of the compounds, with a few exceeding 120%. Furthermore, the screening method was verified with 20 plastic products used in daily life and 170 recycled plastic particle samples from imports. The experimental results showed that phthalates were the main additives in plastic products, and among 170 recycled plastic particle samples, 14 samples were found to contain restricted additives. The main additives in recycled plastics were bis(2-ethylhexyl) phthalate, di-iso-nonyl phthalate, hexabromocyclododecane, and 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether at concentrations between 374 and 34785 mg/kg, except for some results that exceeded the maximum measured value of the instrument. Compared with traditional methods, an important advantage is that this method simultaneously tests for 33 additives without sample pretreatment, covering a variety of additives limited by laws and regulations, and therefore can provide more comprehensive and thorough inspections.