DETERMINATION OF MERCURY SPECIES IN GAS-CONDENSATES BY ONLINE COUPLEDHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND COLD-VAPOR ATOMIC-ABSORPTION SPECTROMETRY

A method for the speciation of mercury in gas condensates is reported, Mercury(II) chloride (HgCl2), methylmercury chloride (MeHgCl), phenyl mercury acetate (PhHgAc) and diphenylmercury (Ph(2)Hg) are separated b y reversed-phase high-performance liquid chromatography (HPLC) using g radient elution, Prior to the determination, the organic ligands and t he matrix were destroyed by oxidation with K2Cr2O7. Mercury is detecte d with cold-vapor atomic absorption spectrometry (CVAA), where the mer cury compounds are reduced to metallic mercury by a treatment with NaB H4. In a continuous-flow system the concentrations of the reagents use d are optimized using a modified simplex algorithm, Detection limits f or mercury are at the 10 ng ml(-1) level, Analysis of multi-compound m ixtures indicates that chemical reactions between HgCl2 and Ph(2)Hg an d between MeHgCl acid Ph(2)Hg take place, The method developed was app lied to the speciation of mercury in gas condensates and did not requi re use of any solvent extraction or chemical derivatization steps, In the gas condensates, mercury(lI) compounds were found to be present at the 100 ng ml(-1) level.