Simultaneous determination of Hg(II) and alkylated Hg, Pb, and Sn species in human body fluids using SPME-GC/MS-MS

A GC/MS-MS method for the determination of Hg(II) and alkylated Hg, Pb, and Sn species in human urine is described. Separation and identification of the metal species are performed by capillary gas chromatography coupled with an ion-trap mass spectrometer with electron impact ionization in the tandem-MS mode. For sample preparation a very promising technique was applied that is based on a derivatization with sodium tetraethylborate followed by headspace solid phase microextraction (SPME). Operation of the used ion trap in the tandem-MS mode yields in improved detection limits because of a signal-to-noise ratio that is at least one order of magnitude better than in the MS mode. The detection limits in real matrices like urine are between 7 and 22 ng/L for all species investigated. Urinary levels of inorganic Hg in non-occupationally exposed persons with and without dental amalgam were found to be between 0.1 and 1.4 μg/L. A reference material (“ClinRep, Level I”) was used for quality assurance. Compared to the coupling of GC with ICP-MS (“inorganic” MS), the advantage of the proposed method using an “organic” MS is that (i) the species can be directly identified via their precursor and daughter ions and (ii) analysis can be performed with a commercially available hyphenated technique at moderate costs and needs no lab-made interfacing. Moreover, it offers a real multi-element/multi-species capability with low detection limits and a minimum of sample preparation.