加速溶剂萃取分离-气相色谱-质谱法测定土壤中多溴二苯醚和六溴联苯的含量

Determination of Polybromo Diphenyl Ethers and Hexabromobiphenyl in Soil by Gas Chromatography-Mass Spectrometry with Separation by Accelerated Solvent Extraction

称取经风干和剔除砂、石等杂质并研磨通过0.18 mm孔径筛的土壤样品2.000g与2.0g硅藻土混合,加入2 000μg·L-1同位素内标溶液(MBDE-MXFS)50μL和5 000μg·L-113C12-BDE-209标准溶液40μL,用正己烷-二氯甲烷(1+1)混合液进行加速溶剂萃取(ASE)。将所得萃取液浓缩至1~2mL,通过多层复合酸碱硅胶层析柱净化,用正己烷100mL洗脱,收集洗脱液,使其浓缩至1~2mL,再经氮吹浓缩至0.1mL,加入2 000μg·L-1 13C12-BDE-138进样内标溶液50μL,定容至1.0mL,进样进行气相色谱-质谱分析。测定三溴至七溴代二苯醚(BDEs)和六溴联苯(BB-153)时,按气相色谱-电子轰击离子源-低分辨质谱工作条件并选用Rtx-1614色谱柱(30m×250μm,0.10μm);测定BDE-209时,按气相色谱-负化学电离源-低分辨质谱工作条件并选用Rtx-1614色谱柱(15m×250μm,0.10μm)。测得BDE-209的线性范围为50.0~1 000μg·L-1,其余7种PBDEs和BB-153的线性范围均为5.00~500μg·L-1;检出限(3s)在0.04~0.51μg·L-1。用标准加入法进行回收试验,测得回收率为82.6%~112%;测定值的相对标准偏差(n=5)为1.8%~8.6%。

After air-drying and rejecting mixed sand and stone, the soil was gound to pass the sieve with mesh- diameter of 0. 18 mm. A portion （2. 000 g） of the soil sample was mixed homogeneously with 2.0 g of diatomite, and to this sample mixture, 50 ~L of the isotopic internal standard solution （2 000μg·L^-1 MBDE MXFS） and 40μL of 5 000 μg· L^-1 ^13C2-BDE-209 standard solution were added and this mixture was extracted by accelerated solvent extraction （ASE） with mixed solvent of n-hexane and dichloromethane （1＋1）. The extract obtained was evaporated to 1-2 mL, and purified by passing through muhilayer silica gel column. Analytes on the column were then eluted with 100 mL of n-hexane, and the eluate was collected and evaporated to 1 2 mL and further concentrated to 0. 1 mL by Ne-blowing. Then 50/aL of sample introducing internal standard solution of 2 000μg·L^-1 ^13C12 BDE-138 were added and its total volume was made up to 1.0 mL, which was used for GC-MS analysis. For determination o5 trilbrono- to hepta bmmo diphenyl ethers （PBDEs） and hexabromobiphenyl （BPr 153）, instrumental conditions of GC-EI/LRMS and chromatographic column of Rtx 1614 （30 m×250μm, 0. 10μm） were used, while for determination of BDE 209, the instrumental conditions of GC-NCI/ LRMS and the column of Rtw1614 （15 m×250 tam, 0. 10 pro） were used. Linearity range found for BDE-209 was 50. 0-- 1000μg·L^-1, and those for the remainder 7 PBDEs and BB-153 were found same 5. 00--500 μg·L^-1. Values of detection limits （3s） found ranged from 0. 04 to 0. 51μg·L^-1. Recovery was tested by standard addition method, and values of recovery found were in the range of 82. 6%--112%. RSDs （n=5） found ranged from 1.80% to 8. 6%.