title: Analytical developments for the determination of monomethylmercury complexes with low molecular mass thiols by reverse phase liquid chromatography hyphenated to inductively coupled plasma mass spectrometry.
abstract: The behavior of monomethylmercury (MMHg) is markedly influenced by its distribution among complexes with low molecular mass (LMM) thiols but analytical methodologies dedicated to measure such complexes are very scarce up to date. In this work, we selected 15 LMM thiols often encountered in living organisms and/or in the environment and evaluated the separation of the 15 corresponding MMHg-thiol complexes by various high performance liquid chromatography (HPLC) columns. Two C18 (Phenomenex Synergi Hydro-RP and LunaC18(2)), two phenyl (Inertsil Ph 3 and 5μm) and one mixed-mode (Restek Ultra IBD) stationary phases were tested for their retention and resolution capacities of the various complexes. The objective was to find simple separation conditions with low organic contents in the mobile phase to provide optimal conditions for detection by inductively coupled plasma mass spectrometry (ICPMS). The 15 complexes were synthesized in solution and characterized by electrospray ionization-mass spectrometry (ESI-MS). The C18 columns tested were either not resolutive enough or too retentive. The 3μm phenyl stationary phase was able to resolve 10 out of the 15 complexes in less than 25min, under isocratic conditions. The mixed-mode column was especially effective at separating the most hydrophilic complexes (6 complexes out of the 15), corresponding to the main LMM thiols found in living organisms. The detection limits (DLs) for these two columns were in the low nanomolar range and overall slightly better for the phenyl column. The possibilities offered by such methodology were exemplified by monitoring the time-course concentrations of four MMHg-thiol complexes within a phytoplankton incubation containing MMHg in the presence of an excess of four added thiols.
authors.affiliation: Department of Chemistry, Umeå University, 90187 Umeå, Sweden. Electronic address: s_bouchet@outlook.com.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bouchet
authors.affiliation: Department of Chemistry, Umeå University, 90187 Umeå, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Björn
mesh_terms: D000460:Chlorophyta / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D004785:Environmental Pollutants / Q000032:analysis*; D057230:Limit of Detection; D008767:Methylmercury Compounds / Q000032:analysis*; D008970:Molecular Weight; D010839:Phytoplankton / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013438:Sulfhydryl Compounds / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D013438:Sulfhydryl Compounds; D014874:Water Pollutants, Chemical
keywords: Complexes distribution; Inductively coupled plasma; Mass spectrometry; Monomethylmercury; Retention; Thiol ligands