Characterization of mercury contamination in petroleum hydrocarbons (PHs) is necessary in order to assess the risk of corrosion of the processing infrastructure and to assess the level of human exposure to Hg-containing substances. Here we present an accurate and sensitive method for determination of Hg species in PHs by headspace sampling with a possibility of on-line pre-concentration using in-tube extraction (ITEX) combined with gas chromatography–inductively coupled plasma mass spectrometry (GC-ICP-MS) analysis. Mercury species were first extracted from the PHs matrix into an aqueous phase via dithizone chelation and subsequently converted with sodium tetrapropyl borate into volatile derivatives which could be sampled from the headspace prior to GC-ICP-MS analysis. For concentrations in the ng kg^–1 range, the on-line ITEX method was applied, whereas the μg kg^–1 range was accessible by static headspace. Quantitation of Hg species was carried out by a double isotope dilution method, with quantitative recoveries of methylmercury (MeHg, average 101 ± 5%) and inorganic mercury (InHg, average 97 ± 7%) by direct headspace injection. Average recoveries of Hg spikes after on-line ITEX pre-concentration were 95 ± 3% for MeHg and 98 ± 8% for InHg. The detection limits for MeHg and InHg were 428 and 46 ng kg^–1 when measured by static headspace, and 2.4 ng kg^–1 and 1.7 ng kg^–1 by on-line ITEX pre-concentration. The accuracy of the pre-concentration method was demonstrated by analysis of a crude oil standard reference material (NIST 2722) certified for InHg.

中文翻译：

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顶空管微萃取和GC-ICP-MS测定石油烃中的汞

为了评估加工基础设施腐蚀的风险并评估人类接触含Hg物质的水平，必须对石油烃（PHs）中的汞污染进行表征。在这里，我们介绍了一种通过顶空进样测定PH中的Hg种类的准确而灵敏的方法，并且可以使用管内萃取（ITEX）与气相色谱-电感耦合等离子体质谱（GC-ICP）结合进行在线预富集-MS）分析。首先通过双硫zone螯合法从PH基质中将汞物种萃取到水相中，然后用四丙基硼酸钠将其转化为挥发性衍生物，可以从顶空进样，然后进行GC-ICP-MS分析。浓度为ng kg ^–1范围，则应用在线ITEX方法，而静态顶空可访问µg kg ^–1范围。通过双同位素稀释法对汞物种进行定量，通过直接顶空进样定量回收甲基汞（MeHg，平均101±5％）和无机汞（InHg，平均97±7％）。在线ITEX预浓缩后，MeHg的Hg峰值平均回收率为95±3％，InHg为98±8％。通过静态顶空测量时，MeHg和InHg的检出限分别为428和46 ng kg ^–1，以及2.4 ng kg ^–1和1.7 ng kg ^–1通过在线ITEX预浓缩。通过分析认证为InHg的原油标准参考物质（NIST 2722），证明了预浓缩方法的准确性。