气相色谱-负化学源质谱法对土壤中BDE-209含量的测定

Determination of BDE-209 in soil by gas chromatography-negative chemical ionization mass spectrometry

为准确测定土壤中BDE-209的含量,通过采用加速溶剂萃取、制作BDE-209在多层硅胶柱上的流出曲线、优化仪器条件,应用碳13标记同位素作为定量内标,建立了基于15 m色谱柱的气相色谱-负化学源质谱法。进一步对测量过程中引入的不确定度来源进行分析,计算各不确定度分量,最后合成标准不确定度。结果表明,BDE-209标准曲线在10～1 000 ng/mL浓度范围内具有良好的线性,相关系数为0.999 3,方法检出限为0.87 ng/g,样品不同浓度水平加标回收率范围为91.6%～103%,相对标准偏差小于5%。方法分析过程中的不确定度主要来源于样品称量、样品定容、前处理以及分析处理4个环节。其中分析数据引入的不确定度分量贡献最大,为82.5%,前处理、样品称量及定容过程引入的不确定度分量贡献率分别为12.6%、2.53%和2.43%。合成标准不确定度为0.078,置信水平95%,k=2时,相对扩展不确定度为0.16。研究结果为提高测定土壤中BDE-209结果准确度提供理论依据,为其他多溴二苯醚的测定提供借鉴。

A method for determination BDE-209 in soil samples has been developed by using accelerated solvent extraction-multilayer silica gel column cleanup coupled with gas chromatography/negative chemical ionization mass spectrometry.Furthermore,the sources of uncertainty produced in measurement process were analyzed.Each uncertainty components were calculated to combine the standard uncertainty,and then,the relative expanded uncertainty was proposed.The results showed good linearity in the range of 10-1 000 ng/mL with correlation coefficients was 0.999 3.The limit of detection of BDE-209 in soil samples was 0.87 ng/g.The recoveries with different concentrations were between 91.6%-103%and the relative standard deviations were less than 5%.There were four uncertainty components in BDE-209 analysis of soil,which was:weighing,constant volume,preparation,and analysis.The predominant uncertainty of 82.5%was from analysis,the others from preparation,weighing,and constant volume were 12.6%,2.53%,2.43%respectively.The results showed that the resulting combined relative standard uncertainty was determined as 0.078 and the expanded uncertainty as 0.16 at confidence probability 95%,coverage factor k=2.The uncertainty evaluation of the determination process can provide reliable theoretical basis for detection of BDE-209 in soils and improve the accuracy of test results.Our results can also provide references for the determination of other PBDE congeners.