Selective determination of tin (II) ion in water by solvent extraction with salicylidenamino-2-thiophenol followed by reversed-phase high-performance liquid chromatography with photometric detection

A selective determination method for tin (11) ion by reversed-phase high-performance liquid chromatography (HPLC) has been developed. Tin (Sn) ion was extracted into 4-methyl-2-pentanon at pH 4.5 as salicylideneamino-2-thiophenol (SATP) chelate. Sn-SATP chelate in the organic layer was then separated on a phenyl column with an eluent of methanol/water mixture containing 1 mmol/L NaCl and detected at 430 nm. The correlation coefficients of the calibration curves obtained with 5 mL Sn standards were more than 0.999 over the range of 10 ng/mL (ppb) to 1 mug/mL (ppm). The detection limit of Sn ion in 5 mL solution was 1.4 ppb, which corresponded to 3 times the standard deviation of the blank peak area. The detection limit was better than that of inductively coupled plasma-atomic emission spectroscopy (ICP-AES, 2 ppm). Reproducibility for 50 ppb Sri standard was 2.3% as relative standard deviation (N=7). Recovery tests were carried out by the presented HPLC method and ICP-AES with a spiked river water sample. The recoveries obtained by the HPLC method were 100.6% (500 ppb) and 96.3% (50 ppb). Since ICP-AES could not detect Sn ion at the ppb level, a recovery test was carried out for 5 ppm Sn with 99.8% recovery. Effects of foreign ions on the method were investigated with 55 metal ions. Almost none of the ions interfered except for Hg(II) and Zr(IV).