加速溶剂萃取-硅胶柱净化-碱性氧化铝柱分离-气相色谱三重四极杆质谱法测定土壤中的二噁英类化合物

建立了加速溶剂萃取(ASE),酸性硅胶柱、复合硅胶柱及碱性氧化铝柱纯化分离,气相色谱-三重四极杆质谱测定土壤中二噁英/呋喃(PCDD/Fs)、多氯联苯(PCBs)、多氯萘(PCNs)的分析方法.选用正己烷-二氯甲烷(50∶50, V/V)作为ASE的提取溶剂,设定提取温度为120℃,加标回收实验表明本方法可行.用100 mL正己烷-二氯甲烷(95∶5, V/V)及50 mL正己烷-二氯甲烷(50∶50, V/V)依次淋洗碱性氧化铝柱,得到组分A(PCBs及PCNs)与组分B(PCDD/Fs),实现了PCDD/Fs与另外两种化合物的分离,排除了同系物间及其它杂质的干扰.使用同位素稀释-气相色谱三重四极杆质谱法(GC-MS/MS), 在选择反应监测(Selected reaction monitoring, SRM)模式下测定PCDD/Fs、PCBs和PCNs,3种化合物的仪器检出限(LOD)范围分别为0.04~0.25 μg/L, 0.10~0.20 μg/L和0.01~0.05 μg/L,目标物平均相对响应因子(RRF)的相对标准偏差(RSD)均小于13%.基质土加标实验中,3种化合物13C标记的同位素内标回收率的范围分别为50%~95%,51%~103%, 49%~74%.实际样品的分析结果表明,PCDD/Fs、PCBs及PCNs在土壤样品中的总含量范围分别为16.1~1148 pg/g、6.6~152.6 pg/g及10.9~99.5 pg/g,且样品测定结果与高分辨质谱测定结果相吻合.

Determination of Dioxin-like Compounds in Soil byAccelerated Solvent Extraction-Silica Gel Column Cleanup-BasicAlumina Column Separation Coupled with Gas Chromatography-Triple Quadrupole Mass Spectrometry

A method for determination of PCDD/Fs, PCBs and PCNs in soil sample was developed by using accelerated solvent extraction (ASE)-silica gel column cleanup-basic alumina column separation coupled with GC-MS/MS.The sample was extracted by ASE with Hexane-methylene chloride (Hex-DCM, 50∶50, V/V) at 120℃.The basic alumina column was used to separate PCDD/Fs, PCBs and PCNs.The extracts were eluted with Hex-DCM (95∶5, V/V) to obtain PCBs and PCNs, followed by Hex-DCM (50∶50, V/V) to obtain PCDD/Fs.The limits of detection (LOD) were in the range of 0.04-0.25 μg/L, 0.10-0.20 μg/L and 0.01-0.05 μg/L for PCDD/Fs, PCBs, PCNs, respectively.The relative standard deviations (RSDs) of average relative response factors (RRF) were below 13%.The recoveries of 13C-labeled internal standards of the three classes of analytes were 50%-95%, 51%-103% and 49%-74%, respectively.Concentrations of ∑PCDD/Fs, ∑PCBs and ∑PCNs in soil samples were 16.1-1148 pg/g, 6.6-152.6 pg/g and 10.9-99.5 pg/g, respectively.The results were consistent with that of high resolution mass spectrometer.