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    固相萃取-液相色谱-串联三重四极杆质谱法同时测定水中3种六溴环十二烷和四溴双酚A的含量

    Simultaneous Determination of 3 Hexabromocyclododecanes and Tetrabromo-bisphenol A in Water by Liquid Chromatography-Tandem Triple Quadrupole Mass Spectrometry with Solid Phase Extraction

    • 摘要: 用棕色采样瓶采集水样,每升水样中加入80 mg硫代硫酸钠和5 mL甲醇。取1 L处理后的样品,加入20.0 μL 1.00 mg·L−1提取内标(以碳同位素标记的目标化合物为提取内标)溶液,混匀,抽滤过0.45 μm滤膜,收集滤液。将抽滤后的滤膜剪碎置于15 mL离心管中,加入5 mL丙酮,超声提取20 min,过0.45 μm聚四氟乙烯(PTFE)针头式过滤器,该滤液与抽滤后的滤液合并,过ChromP固相萃取柱(依次用二氯甲烷、丙酮、甲醇和水各10 mL活化),氮气吹扫固相萃取柱10 min,用15.0 mL体积比9∶1的二氯甲烷-丙酮混合溶液洗脱,收集洗脱液,氮吹至近干,残余物用甲醇溶解并定容至1.0 mL,加入20.0 μL 1.00 mg·L−1进样内标以氘代同位素标记的α-六溴环十二烷(α-HBCD)为进样内标溶液,混匀,过0.22 μm PTFE针头式过滤器,采用液相色谱-串联三重四极杆质谱法测定滤液中3种六溴环十二烷(HBCDs,包括α-HBCD、β-HBCD和γ-HBCD)和四溴双酚A(TBBPA)的含量。以Extend C18色谱柱为固定相,以不同体积比的水-有机相(体积比1∶1的甲醇-乙腈混合溶液)混合液为流动相进行梯度洗脱,采用电喷雾离子(ESI)源,在负离子(ESI)扫描模式下进行多反应监测(MRM)模式质谱分析。结果表明,4种目标化合物的质量浓度在2.00~200 μg·L−1内和提取内标的质量浓度之比与对应的响应强度之比呈线性关系,检出限(3.143s)为0.5~0.8 ng·L−1。按照标准加入法进行回收试验,回收率为88.4%~129%,测定值的相对标准偏差(n=6)为2.3%~15%。方法用于32个地表水样品和2个废水样品的分析,29个地表水样品中均未检出目标化合物,其余样品中HBCDs的检出量为0.5~1.9 ng·L−1,TBBPA的检出量为1.4~17.8 ng·L−1

       

      Abstract: The water samples were collected with brown sampling bottles, and 80 mg of sodium thiosulfate and 5 mL of methanol were added to each liter of the water sample. 1 L of the treated sample was taken, and 20.0 μL of 1.00 mg·L−1 extraction internal standard (carbon isotope labeled target compounds were used as extraction internal standards) solution was added. After mixing well, the sample was suction-passed through a 0.45 μm filter membrane, and the filtrate was collected. The suction-filtered filter membrane was cut into pieces and placed in a 15 mL-centrifuge tube. 5 mL of acetone was added, and the mixture was extracted by ultrasound for 20 min and passed through a 0.45 μm polytetrafluoroethylene (PTFE) needle filter. The filtrate was combined with the previously suction-filtered filtrate and the mixture was passed through a ChromP solid phase extraction column (activated successively with 10 mL of dichloromethane, 10 mL of acetone, 10 mL of methanol and 10 mL of water). The solid phase extraction column was purged with nitrogen for 10 min and eluted with 15.0 mL of the mixed solution of dichloromethane and acetone at a volume ratio of 9∶1. The eluate was collected and blown to near dryness with nitrogen, and the residue was dissolved and made its volume up to 1.0 mL with methanol. 20.0 μL of 1.00 mg·L−1 injection internal standard deuterated isotope labeled α-hexabromocyclododecane (α-HBCD) was used as injection internal standard solution was added, and after mixing well, the solution was passed through a 0.22 μm PTFE needle filter. The 3 hexabromocyclododecanes (HBCDs) including α-HBCD, β-HBCD and γ-HBCD,and tetrabromobisphenol A (TBBPA) in the filtrate were determined by liquid chromatography-tandem triple quadrupole mass spectrometry. Extend C18 column was used as the stationary phase and the mixed solution composed of water and organic phase (a mixed solution of methanol and acetonitrile at a volume ratio of 1∶1) at different volume ratios was used as the mobile phase for gradient elution. Electrospray ion (ESI) source was used for mass spectrometry. The targets were analyzed by multiple reaction monitoring (MRM) mode in negative ion (ESI) scanning mode. As shown by the results, the mass concentration ratios of 4 target compounds in the range of 2.00-200 μg·L−1 to the extraction internal standards were linearly related to the ratios of their corresponding response intensities, with detection limits (3.143s) in the range of 0.5-0.8 ng·L−1. Test for recovery was made by the standard addition method, giving results in the range of 88.4%-129%, with RSDs (n=6) of the determined values in the range of 2.3%-15%. This method was used for the analysis of 32 surface water samples and 2 wastewater samples, and the target compounds were not detected in 29 surface water samples. The detection amounts of HBCDs were in the range of 0.5-1.9 ng·L−1, and the detection amounts of TBBPA were in the range of 1.4-17.8 ng·L−1 in the remaining samples.

       

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