DETERMINATION OF MERCURY ION IN RIVER WATER BY SOLVENT EXTRACTION WITH 5-METHYL-1,3,4-THIODIAZOLE-2-THIOL FOLLOWED BY REVERSED PHASE HPLC

A determination method for mercury (Hg) ion in river water has been developed by reversed phase HPLC. The Hg(II) ion was quantitatively extracted into benzene from an acidic solution as 5-methyl-1,3,4-thiodiazole-2-thiol (MTT) chelate. The extracted Hg-MTT chelate was then separated on a C18 column with an eluent of methanol/water/0.01mol/L MTT (72:26:2, v/v) and detected at 270nm. The correlation coefficients of the calibration curves obtained with 5mL Hg standards were more than 0.999 in the range of 0.1 to 10g/mL (ppm). The detection limit of the Hg ion in 5mL of water was 0.05ppm by a signal to noise ratio of 3. Relative standard deviations of peak areas (N=6) for 5 and 0.5ppm Hg standards were less than 1%. Effects of foreign ions on the determination of 0.4ppm Hg were investigated with 57 metal ions. Almost none of the ions interfered except for Au(III), Cu(II), Pt(IV), Ag(I), Cr(VI), and Pd(II) ions. The recoveries with a spiked river water sample for 5 and 0.5ppm Hg ion (N=6) were 100.0 +/- 0.8% and 99.3 +/- 0.9%, respectively.