顶空气相色谱和气相色谱-质谱联用法检测血液中的二氯甲烷

目的 建立血液中二氯甲烷的气相色谱-质谱（GC-MS）定性检测和顶空气相色谱（HS-GC）定量检测方法，为二氯甲烷中毒或致死案件的法医学鉴定和分析提供可靠依据。方法 取0.5 mL血液，以氯仿为内标，加入到顶空瓶，经65℃加热后抽取瓶中气体用GC-MS进行定性方法学验证，用HS-GC进行定量方法学验证，并将该方法应用于案件鉴定。结果 GC-MS定性验证：空白血液中无干扰，添加血样中二氯甲烷色谱峰特异且峰型良好，质谱特征碎片离子特异；方法检出限（LOD）为5μg/mL。HS-GC定量验证：二氯甲烷与乙醇等常见挥发性化合物色谱峰分离良好，分离度均>1.5；方法定量限（LOQ）为20μg/mL，在20～1 000μg/mL范围内线性关系良好，R>0.999；日内/日间精密度良好（RSD均<15%），准确度高（相对误差δ<15%）。2例二氯甲烷致死案件死者血液中均检出二氯甲烷，质量浓度分别为470μg/mL、915μg/mL。结论 该方法快速、稳定且结果可靠，可用于疑似二氯甲烷中毒或致死案件血液中二氯甲烷的法医毒物学定性定量分析。

Determination of Dichloromethane in Blood with Headspace Gas Chromatography and Gas Chromatography-Mass Spectrometry

  Objective  To establish a method for qualitative determination of dichloromethane (DCM) in blood by gas chromatography-mass spectrometry (GC-MS) and quantitative determination of DCM in blood by headspace gas chromatography (HS-GC), and to provide reliable support for forensic examination and analysis of poisoning or deaths caused by DCM.   Methods  0.5 mL blood sample was collected, added into headspace vial with chloroform as the internal standard, and processed by heating at 65 °C and evacuation treatment. The intermediate gas in the headspace vial was analyzed by GC-MS for qualitative validation of the method and by HS-GC for quantitative validation of the method. The method was then applied in forensic case analysis.   Results  Qualitative validation of the examination method by GC-MS found that the chromatographic peak and mass spectral characteristic ions were specific in samples added with DCM, and that no interference was observed in the blank negative samples. The limit of detection (LOD) was 5 μg/mL. Quantitative method validation by HS-GC found that the chromatographic peak of DCM was well separated from those of eight other volatile compounds, with the resolution>1.5 in all cases; the lower limit of quantification (LOQ) was 20 μg/mL and good linearity was shown within the range of 20 and 1000 μg/mL, R>0.999; the intra-day test precision and inter-day test precision were good (relative standard deviation, or RSD<15% for both) and test accuracy was high (relative error, or δ<15%). With the method established in the study, DCM was detected successfully in the blood of two fatal cases caused by DCM poisoning, with the blood concentration being 470 μg/mL and 915 μg/mL, respectively.   Conclusion  This method is shown to be a rapid, stable and accurate approach to the qualitative and quantitative forensic and toxicological analysis of DCM in blood in DCM poisoning cases or deaths caused by DCM.