title: Determination of methylmercury and inorganic mercury by coupling short-column ion chromatographic separation, on-line photocatalyst-assisted vapor generation, and inductively coupled plasma mass spectrometry.
abstract: We have combined short-column ion chromatographic separation and on-line photocatalyst-assisted vapor generation (VG) techniques with inductively coupled plasma mass spectrometry to develop a simple and sensitive hyphenated method for the determination of aqueous Hg(2+) and MeHg(+) species. The separation of Hg(2+) and MeHg(+) was accomplished on a cation-exchange guard column using a glutathione (GSH)-containing eluent. To achieve optimal chromatographic separation and signal intensities, we investigated the influence of several of the operating parameters of the chromatographic and photocatalyst-assisted VG systems. Under the optimized conditions of VG process, the shortcomings of conventional SnCl(2)-based VG techniques for the vaporization of MeHg(+) was overcome; comparing to the concentric nebulizer-ICP-MS system, the analytical sensitivity of ICP-MS toward the detection of Hg(2+) and MeHg(+) were also improved to 25- and 7-fold, respectively. With the use of our established HPLC-UV/nano-TiO(2)-ICP-MS system, the precision for each analyte, based on three replicate injections of 2 ng/mL samples of each species, was better than 15% RSD. This hyphenated method also provided excellent detection limits--0.1 and 0.03 ng/mL for Hg(2+) and MeHg(+), respectively. A series of validation experiments--analysis of the NIST 2672a Standard Urine Reference Material and other urine samples--confirmed further that our proposed method could be applied satisfactorily to the determination of inorganic Hg(2+) and MeHg(+) species in real samples.
authors.affiliation: Department of Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, 30013 Hsinchu, Taiwan.
authors.forename: Kuan-ju
authors.initials: KJ
authors.lastname: Chen
authors.forename: I-hsiang
authors.initials: IH
authors.lastname: Hsu
authors.forename: Yuh-chang
authors.initials: YC
authors.lastname: Sun
mesh_terms: D002384:Catalysis / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D005561:Formates / Q000737:chemistry; D005978:Glutathione / Q000032:analysis; D006863:Hydrogen-Ion Concentration / Q000528:radiation effects; D008027:Light; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D049329:Nanostructures / Q000737:chemistry; D009862:Online Systems; D012015:Reference Standards; D012997:Solvents / Q000737:chemistry; D013054:Spectrophotometry, Atomic / Q000379:methods*; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D014835:Volatilization / Q000528:radiation effects
chemical_list: D005561:Formates; D008767:Methylmercury Compounds; D012997:Solvents; C030544:formic acid; C009495:titanium dioxide; D014025:Titanium; D008628:Mercury; D005978:Glutathione