| Since mercuric mercury and methylmercury display different toxicological properties in mammals, methods for their separation, identification, and quantification in dietary items must be available. By coupling a size-exclusion or a reversed-phase high performance liquid chromatographic system on-line to a Hg-specific spectroscopic detector (Flame Atomic Absorption Spectrometer or Inductively Coupled Plasma Atomic Emission Spectrometer), a novel, rapid, isocratic, and affordable separation of these mercurials was sought using a thiol-containing 100% aqueous mobile phase. After systematically optimizing the mobile and stationary phase, ideal separation was achieved with a phosphate-buffered cysteine-containing mobile phase (50 mM phosphate, 10 mM L-cysteine, pH 7.5, 1.0 mL/min flow rate) and a styrene-divinylbenzene copolymer stationary phase (Hamilton PRP-1 column). For the first time, the underlying molecular separation mechanism was addressed by structural characterization of the Hg complexes eluting from the column by Hg extended X-ray absorption fine structure. The separation method was successfully applied to analyze spiked human urine. |
