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挥发性硫化合物( volatile sulfur compounds, VSCs)能抑制所有有氧细胞线粒体呼吸链末端的细胞色素氧化酶[1],造成细胞窒息,对人体的危害性极大. 司法实践中,硫化氢(H2S)是最常见的VSCs致死毒物,每年全国会有上百人因H2S中毒致死[2 − 3]. H2S是一种较为常见的神经毒剂,主要依靠呼吸道进入身体,也可以通过皮肤、消化道进行缓慢地吸收. H2S在体内的代谢主要有3条途径:其一,H2S进入人体之后与细胞色素氧化酶等蛋白酶结合,导致蛋白酶失去其原有的作用;其二,硫离子在人体被氧化,形成硫代硫化物、硫酸盐等;其三,H2S甲基化后,生成甲硫醚(dimethyl sulfide, DMS)和甲硫醇(methanethiol, MT),之后甲硫醇会随着时间的推移,逐步转化为甲硫醚[4 − 5]. 第一条途径是导致人体硫化氢中毒的原因,后两条途径为肝脏等器官进行解毒的过程.
因DMS和MT的刺激性气味,很少发生直接摄入而急性中毒的案例,且经过初步检验也易将MT、DMS中毒与H2S中毒区分开。因此,作为H2S在人体内主要的代谢产物,DMS和MT具有一定的标识作用。目前,国内外学者主要通过研究血液中的硫离子、硫代硫酸盐以及硫化血红蛋白等鉴定H2S中毒,如强火生、罗才会、Varlet 、张震等[6 − 9]通过GC-MS或GC-FPD等方法测定血液中的S2-,褚建新、刘春霞等[10 − 11]分别通过分光光度计和荧光探针检测血中的硫化血红蛋白,同时为了提高定量的准确性,Maseda等[12]通过LC-MS方法测定血液和尿液中的硫代硫酸盐. 但是上述方法均存在重复性差、操作复杂等缺点。为了避免此类问题,需对H2S甲基化产生的DMS、MT进行分析. 基于相关文献可知[5,9],在人体内检测出H2S、DMS和MT的存在,可为H2S中毒做出判断. 国内外主要是采用气相色谱-质谱(gas chromatography mass spectrometry, GC-MS)法和气相色谱法检验DMS和MT,王芳琳、吴颖娟[13 − 14]采用GC-MS分别对血中的MT和废水中的DMS进行定性定量,张立江、Ábalos等[15 − 16]采用顶空气相色谱的方法对废水中的DMS、MT进行检验,并对挥发性硫化物性质进行较为全面的研究.
顶空气相色谱法(HS-GC)是一种联合操作技术,采用顶空萃取,可专一性收集样品中的易挥发性成分[17]. HS-GC具有较高的灵敏度和比较迅速的分析速度,可降低共提物引起的干扰,且操作简便[18]. 其简便性、快捷性和准确性满足鉴定机构的检验要求,因此本文拟建立全血中DMS和MT的顶空气相色谱检验方法,以期为公安机关处理硫化氢中毒案件和安全生产等方面提供理论依据和方法支撑.
顶空气相色谱法测定硫化氢中毒血中的甲硫醚和甲硫醇
Determination of dimethyl sulfide and methyl mercaptan in blood by headspace gas chromatography
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摘要: 甲硫醚和甲硫醇作为硫化氢进入人体之后的主要代谢产物,具有一定的标识作用. 针对血液中甲硫醚和甲硫醇的检验进行研究,建立了顶空气相色谱检验方法. 实验采用对含硫化合物具有高灵敏度的火焰光度检测器(FPD),同时发现向0.5 mL血样中加入0.15 g氯化钠可使检出效率得到提升. 本方法血中甲硫醚的标准曲线范围为0.01—2.00 μg·mL−1,相关系数(R2)为0.997,检出限为0.003 μg·mL−1,定量限为0.01 μg·mL−1. 虽然甲硫醇由于自身沸点太低,不适合对其进行定量分析,但对其进行定性检测,也可为硫化氢中毒提供一定的依据. 本研究建立的方法可直接应用于血液中微量甲硫醚和甲硫醇的检测,从而为硫化氢中毒案件的检验鉴定提供依据.Abstract: Methyl sulfide and methyl mercaptan, as the main metabolites of hydrogen sulfide after entering the human body, have certain marking effects. A headspace gas chromatographic method was developed for the detection of methyl sulfide and methyl mercaptan in blood. A flame photometric detector (FPD) with high sensitivity for sulfur-containing compounds was used, and it was found that the addition of 0.15 g sodium chloride to 0.5 mL of blood sample resulted in improved detection efficiency. The standard curve range of this method was 0.01—2.00 μg·mL−1, the correlation coefficient (R2) was 0.997, the limit of detection was 0.003 μg·mL−1, and the limit of quantification was 0.01 μg·mL−1. Although methyl mercaptan is not suitable for quantitative analysis due to its low boiling point, its qualitative detection can also provide a basis for hydrogen sulfide poisoning. The method developed in this study can be directly applied to the determination of trace amounts of methyl mercaptan and methyl mercaptan in blood, thus providing a basis for the identification of hydrogen sulfide poisoning cases.
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Key words:
- gas chromatography /
- methyl sulfide /
- methanethiol /
- hydrogen sulfide.
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表 1 15份样本的基本信息
Table 1. Basic information for the 15 samples
案件编号
Sequence number简要案情
Brief case死亡人数
Number of deaths1 2022年1月某地员工矿洞内工作时中毒死亡,之后进入的两位救援人员相继中毒死亡. 3 2 2021年9月某地员工井下作业时中毒死亡. 3 3 2021年7月某地因暴雨导致井位上升,使得居住点临近井位的一家六口全部中毒死亡. 6 4 2021年11月某地梁某在猪饲料厂清理粪池时,中毒死亡. 1 5 2021年10月某地工厂员工下水道作业时中毒死亡. 2 表 2 考察酸碱介质对DMS血样峰面积的影响
Table 2. Examining the effect of acid and base media on the peak area of DMS blood samples
0.01 μg·mL−1 DMS 0.2 μg·mL−1 DMS 0.8 μg·mL−1 DMS 去离子水 0 986 5742 20%硫酸 47 6005 93505 10%磷酸 0 0 0 三氯乙酸 0 2063 19965 饱和硼砂 0 782 5320 0.1%氢氧化钠e 0 0 0 表 3 DMS的相关系数、范围、检出限及定量限
Table 3. Correlation coefficient, range, detection limits and quantification limits of DMS
回归方程
Regression equation范围/(μg·mL−1)
Range相关系数
R2LOD/(μg·mL−1) LOQ/(μg·mL−1) DMS y = 153120x1.755 1 0.01—2.00 0.997 0.003 0.01 表 4 DMS血样的回收率和精密度
Table 4. Recovery rates and precision of DMS blood samples
全血样品浓度/ (μg·mL−1)
Concentrations of whole blood samples回收率/%
Average recovery rateRSD/% 日内精密度
within-day precision日间精密度
Inter-day0.8 96 1.6 2.1 0.2 94 2.8 3.5 0.02 97 2.6 3.6 表 5 硫化氢中毒案件中DMS的含量
Table 5. Content of DMS in hydrogen sulfide poisoning cases
序号
Sequence number死亡人数
Death tollDMS/(μg·mL−1) 是否检出MT
Whether MT is detected① 3 0.430 √ 0.305 √ 0.280 √ ② 3 0.376 √ 0.296 × 0.215 × ③ 6 0.067 × 0.016 × 0.016 × 0.078 √ 0.093 × 0.027 √ ④ 1 0.247 √ ⑤ 2 0.218 √ 0.079 × -
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