摘要
建立了固相萃取结合高效液相色谱-电喷雾离子化-四极杆串联飞行时间质谱(HPLC-ESI-QTOF/MS)测定塑料制品中短链氯化石蜡(SCCPs)的方法。在ESI离子源中,无需添加氯代有机溶剂,以[M-H]~-离子检测。选取C_(10~13), Cl_(5~13)共30个SCCPs分子中丰度最高的两个同位素峰为定量与定性离子,通过高分辨质谱的精确质量数排除了相近分子量中链氯化石蜡(MCCPs)的干扰,解决了低分辨质谱对SCCPs检测结果不佳的问题。样品经二氯甲烷超声提取,提取液经硅胶柱净化,用正己烷-二氯甲烷(4∶1,V/V)洗脱。氯含量51.5%~63.0%的SCCPs仪器检出限为0.01~0.05 mg/L,方法检出限与定量限分别为1.4和4.6μg/g。在5、20和50μg/g加标水平下,回收率分别为118.0%±8.2%、81.9%±6.9%、77.8%±6.6%,日内相对标准偏差与日间相对标准偏差分别为5.7%与8.1%。对已知C_(10~13)含量的烷烃原料氯化后SCCPs含量进行测定,结果表明,烷烃中C_(10~13)含量与氯化后SCCPs含量一致,表明本方法的检测结果准确。4类塑料制品中SCCPs的测定结果表明,电缆与跑道中SCCPs含量较高(555~1049μg/g),玩具中SCCPs浓度较低(1.86~6.56μg/g)。
A method of high performance liquid chromatography coupled with electron spray ionization quadrupole time-of-flight mass spectrometry was established for analysis of short chain chlorinated paraffins(SCCPs) in plastic. No chlorine solvent was added and SCCPs were quantified by their [M-H]~- ions. For each congener group of SCCPs with carbon chain lengths in 10-13 and chlorine substituents in 5-13, the two most abundant m/z signals were extracted from the full-scan mass spectra as the quantitative and qualitative ions. The influence of medium chain chlorinated paraffins(MCCPs) was eliminated efficiently based on the high resolution of the mass spectrometry. Plastic samples were extracted by dichloride methane and purified by silica gel solid phase extraction column. SCCPs were eluted by hexane/dichloride methane(1∶1, V/V). The instrumental detection limits(IDLs) were 0.01-0.05 mg/L for SCCPs with chlorine content from 51.5%-63%. Method detection limit(MDL) and quantitative limit were 1.4 μg/g and 4.6 μg/g, respectively. Recoveries of SCCPs were 118.0%±8.2%, 81.9%±6.9% and 77.8%±6.6%, at spiking concentrations of 5 μg/g, 20 μg/g and 50 μg/g, respectively. The intra-and inter-day variations were 5.7% and 8.1%, respectively. The quantitative results verified that SCCPs concentration in CPs were similar with the short chain alkane in the corresponding paraffin, which demonstrated the accuracy of this method. This method was applied in determination of four kinds of plastic samples. Cable and track presented to have a high concentration of SCCPs within the range of 555-1049 μg/g. Plastic toys had lower concentrations of SCCPs in the range of 1.86-6.56 μg/g.
引文
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