Solid Phase Extraction and Spectrophotometric Determination of Mercury in Tobacco and Tobacco Additives with p-Sulfobenzylidenerhodanine as Chromogenic Reagent

A highly sensitive, selective and rapid method for the determination of mercury based on the reaction of mercury(II) with p-sulfobenzylidenerhodanine (SBDR) and the solid phase extraction of the colored chelate with a C₁₈ cartridge has been developed. In the presence of pH 3.8 acetate buffer solution and Tween-80 medium, SBDR reacts with mercury to form a red chelate of a molar ratio of 1:2 (mercury to SBDR). This chelate was enriched by solid phase extraction with a C₁₈ cartridge and eluted from the cartridge with ethanol (containing 5% acetic acid). The enrichment factor of 50 was achieved. In the ethanol medium, the molar absorptivity of the chelate is 1.28×10⁵L·mol^–1·cm^–1 at 545nm. Beers law is obeyed in the range of 0.011.2µgmL^–1 in the measured solution. The relative standard deviation for eleven replicate samples of 0.01µgmL^–1 level is 1.52%. This method can be applied to the determination of mercury in tobacco and tobacco additives with good results.