Selective Determination of Mercury(II) Ion by Solvent Extraction with N‐(Dithiocarboxy)sarcosine, Diammonium Salt Followed by Ligand Exchange and Reversed‐Phase HPLC with Photometric Detection

Abstract

Mercury(II) ion was reacted with N‐(dithiocarboxy)sarcosine (DTCS), diammonium salt and then extracted into 1‐hexanol as Hg‐DTCS chelate at pH 1. The organic layers of 15 and 60 µL of 10‐mmol/L hexamethyleneammonium hexamethylenedithiocarbamate (HMA‐HMDC) were injected into a C18 column. The Hg‐DTCS chelate was converted to Hg‐HMDC chelate on the column and detected at 280 nm. The correlation coefficient of the calibration curves obtained with 5 mL of mercury standard was more than 0.999 over the range of 10 ng/mL (ppb) to 10 µg/mL (ppm). The detection limit of Hg ion in 5 mL solution was 1.1 ppb, which corresponded to three times the standard deviation of the blank peak area. Reproducibilities for 5, 0.5, and 0.05 ppm were 1.7%, 1.6%, and 3.3%, respectively (N = 5). Recovery tests were carried out by the HPLC method presented and ICP‐AES with spiked river water samples. The recoveries by the HPLC method for 5 ppm, 0.5 ppm, and 0.05 ppm Hg were 99%, 98%, and 95%, respectively. Effects of foreign ions on the method were investigated with 54 metal ions. Almost all ions did not interfere except for Co(II), Cu(II), Te(IV), and V(V).