Traditional methods for mercury (Hg) speciation in petroleum hydrocarbon matrices by gas chromatography (GC) entail injection of derivatised liquid samples, which very often significantly reduces the lifetime of chromatographic columns. To minimize the negative impact on the column, samples can be diluted. However, doing so, the trace levels of Hg often fall below the limits of detection and online preconcentration techniques when it comes to analytes in organic matrices are greatly limited. We developed a method for Hg speciation using dynamic headspace analysis by GC coupled to ICP-MS, which provides matrix free injections and high preconcentration with ITEX (in-tube-extraction) technology. To avoid oversaturation of the headspace with volatile hydrocarbons, Hg species were first extracted to aqueous matrix and then subsequently alkylated. High preconcentration factor was achieved by repeated online dynamic headspace in-tube-extraction with instruments’ limits of detection of 0.03 pg g-1 and 0.04 pg g-1 for InHg and MeHg, respectively. The quantification was done by species-specific isotope dilution and method validation showed excellent reproducibility and spike recovery.

Dynamic headspace analysis – Hg speciation in petroleum hydrocarbons just got cleaner

255th National Meeting (2018)

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