Selective solid phase extraction and preconcentration of ultra-trace inorganic mercury in water samples using 2,6-dimethyl-morpholine dithiocarbamate

A sensitive and selective solid-phase spectrophotometric method for the determination of trace amounts of Hg(II) cation in water is described. A complex was created with Hg(II) using 2,6-dimethyl-morpholine dithiocarbamate (DMMDTC) to form Hg(II)–(DMMDTC) and this complex was adsorbed onto microcrystalline naphthalene (MN) and then eluted with 5% acetic acid (in ethanol) solution. A preconcentration factor of 187 and a recovery of 95% were observed at pH of 5.0 and for 10 min. of extraction. The separated Hg(II) ions were quantified by using ultraviolet-visible spectrophotometer at 490.0 nm by creating a colored complex with dithizone in Triton X-100 surfactant media. Molar absorptivity and sandell’s sensitivity for the Hg(II)-dithizone were determined as 4.96 × 10⁵ Lmol^?1cm^?1 and 0.4032 µg cm^?2, respectively. The detection limit (LOD) was 1.7 μg L^?1 under the optimized conditions of the analytical method.