SELECTIVE DETERMINATION OF GOLD ION IN RIVER WATER BY SOLVENT EXTRACTION WITH 2-THIAZOLIDINETHIONE, 4-(1-METHYLETHYL)-, (4S)-, FOLLOWED BY REVERSED PHASE HPLC

Abstract

A determination method for gold (Au) ion in river water has been developed by reversed phase HPLC. The Au(III) ion was quantitatively extracted into benzene from a weak alkaline solution as 2-thiazolidinethione, 4-(1-methylethyl)-, (4S)- (TTM) chelate. The extracted Au-TTM chelate was then separated on a C18 column with an eluent of methanol/ethanol/ 0.01 mol/L TTM (70:30:0.1, v/v) and detected at 270 nm. The correlation coefficients of the calibration curves obtained with 5 mL Au standards were more than 0.999 in the range of 1 µg/mL (ppm) to 10 ppm. The detection limit of the Au ion in 5 mL of water was estimated as 0.08 ppm, by a signal-to-noise ratio (S/N) = 3. Relative standard deviations of peak areas (n = 6) for 5 ppm Au standards was 1.0%. The recoveries with a spiked river water sample for 5 ppm Au ion (n = 6) was 99.2 ± 0.6%. Effects of foreign ions on the determination of 2 ppm Au were investigated with 57 metal ions. Almost none of the ions interfered except for Ag(I), Cd(II), and Ti(IV) ions.