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    二次热解吸-气相色谱-质谱法测定聚乳酸线材用于增材制造时产生的有机挥发物

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

    • 摘要: 将聚乳酸(PLA)线材在增材制造时产生的有机挥发物(VOCs)收集在自制的气体收集瓶中,并在20℃下稳定10 min,在经活性炭过滤好的空气的作用下,用TenaX-TA吸附管采集收集瓶中气体20 min,采集的气体经二次热解吸后,以100:1的分流比进入气相色谱,用DB-5MS色谱柱在程序升温条件下分离,进入质谱检测器测定其中主要的9种VOCs (包括苯、甲苯、苯乙烯、乙苯、乙酸丁酯、邻二甲苯、间二甲苯、对二甲苯和正十一烷)含量。在优化的条件下,9种VOCs的保留时间为5.30~23.63 min。结果显示:9种VOCs的质量分别在40~4 000 ng (间二甲苯+对二甲苯)和20~2 000 ng (其他7种组分)内与其对应的峰面积呈线性关系,检出限(3S/N)为1.1~2.5 μg·kg-1;对实际样品进行3个浓度水平的加标回收试验,所得回收率为91.2%~103%,测定值的相对标准偏差(RSD,n=6)为2.0%~8.5%;用此方法分析了6种样品,9种组分均有不同程度检出,总VOCs (TVOCs)含量的RSD (n=11)小于10%。

       

      Abstract: 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%.

       

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