Determination of Volatile Organic Compounds Produced from Polylactic Acid Wire Used for Additive Manufacturing by Secondary Thermal Desorption-Gas Chromatography-Mass Spectrometry

The volatile organic compounds (VOCs) produced from additive manufacturing with polylactic acid wire were collected in the self-made gas collection bottle and stabilized at 20℃ for 10 min. The gas in the bottle was collected with TenaX-TA adsorption tube for 20 min with the aid of air pre-filtered by activated carbon. After secondary thermal desorption, the collected gas was introduced into gas chromatography at a split ratio of 100:1, to get it separated by DB-5MS chromatographic column under programmed temperature condition. The contents of nine major VOCs (including benzene, toluene, styrene, ethylbenzene, butyl acetate, o-xylene, m-xylene, p-xylene and n-undecane) obtained were analyzed by mass spectrometry. Under the optimized conditions, the retention times of 9 VOCs were found in the range of 5.30-23.63 min, and the results showed that linearity relationships between masses of nine VOCs and their corresponding peak areas were kept in the ranges of 40-4000 ng (for the sum of m-xylene and p-xylene) and 20-2000 ng (for the other 7 components), with detection limits (3S/N) in the range of 1.1-2.5μg·kg^-1. The spiked recovery test was made on the actual sample at the 3 concentration levels, giving recoveries in the range of 91.2%-103%, and RSDs (n=6) of measured values were ranged from 2.0% to 8.5%. Six samples were analyzed by this method, and nine components were detected to different degrees,with RSDs (n=11) of TVOCs content less than 10%.