Application of isotopically labeled methylmercury for isotope dilution analysis of biological samples using gas chromatography/ICPMS
Application of isotopically labeled methylmercury for isotope dilution analysis of biological samples using gas chromatography/ICPMS
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DOI：
10.1021/ac011157s
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发表时间：
2002-06-01
影响因子：
7.4
通讯作者：
Donard, OFX
中科院分区：
文献类型：
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作者：
Martín-Doimeadios, RCR;Krupp, E;Donard, OFX
建立了毛细管气相色谱分离-同位素稀释-电感耦合等离子体质谱（CGC/ICPMS）测定生物样品中甲基汞（MMHg）的方法。首次将开放聚焦微波预处理与ID相结合，建立了快速瞬态色谱峰同位素比值测量的最佳条件。发现质量偏差约为1.5%/质量单位，并通过使用在TI-203和TI-205处同时测量的铊信号进行校正。经过质量偏差校正后，发现理论汞比值的偏差低至0.2%。基于峰面积测量的同位素比精密度为0.3% RSD（以绝对汞计）。绝对检测限范围为20-30 fg的Hg-202和Hg-201。采用直接与甲基钴胺素反应的方法合成了富集Hg-201的甲基汞。通过用天然MMHg标准品进行反向同位素稀释来测量MMHg尖峰的浓度。CGC/ICPMS测量同位素比的能力被用来优化样品衍生化水乙基化与NaBEt 4方面的MMHg降解途径和定量回收。已使用生物认证参比物质（CRM-463，DORM-1）验证了所开发方法的准确度。
An isotope dilution (ID) procedure for the determination of methylmercury (MMHg) in biological samples using an inductively coupled plasma mass spectrometer as detector after the capillary gas chromatographic separation (CGC/ICPMS) has been developed. For the first time, open-focused-microwave pretreatment has been used in conjunction with ID. Optimum conditions for the measurement of isotope ratios on the fast transient chromatographic peaks have been established. Mass bias was found to be about 1.5%/mass unit and was corrected by using the simultaneously measured thallium signals at Tl-203 and Tl-205. After mass-bias correction, deviation of the theoretical mercury ratio values was found to be as low as 0.2%. Isotope ratio precisions based on the peak areas measurements were 0.3% RSD for 20 pg injected (as Hg absolute). The absolute detection limits were in the range of 20-30 fg for Hg-202 and Hg-201. Methylmercury enriched in Hg-201 has been synthesized by direct reaction with methylcobalamine. The concentration of the MMHg spike has been measured by reverse isotope dilution with a natural MMHg standard. The capabilities of CGC/ICPMS to measure isotope ratios were used to optimize sample derivatization by aqueous ethylation with NaBEt4 with respect to MMHg degradation pathways and quantitative recovery. The accuracy of the method developed has been validated with biological certified reference materials (CRM-463, DORM-1).