Solid Phase Extraction-Photometric Determination of Trace Amount of Mercury in Environmental Samples with p-Sulfobenzylidene Thiorhodanine

A new chromogenic reagent,namely p-sulfobenzylidene thiorhodanine (abbreviated as SBDTR) was synthesized and its molecular structure verified by elemental analysis,IR spectrometry and 1HNMR. It was found that in an acetate buffer medium of pH 3.5 and in the presence of Tween-80,a stable complex was formed between SBDTR and Hg(Ⅱ) in the mole ratio of 2 to 1. The complex formed was extracted on the Waters Sep-Pak C18 solid-phase extraction (SPE) mini-column and eluted with a definite amount of ethanol. The eluate was collected in a microabsorption cell and its absorbance measured at its absorption maxima 550 nm. Beer′s law was held in the range of 0.1-4.0 mg of Hg(Ⅱ) per liter of solution. Molar absorptivity of the reaction system was found to be 8.42×104L·mol-1·cm-1. Several samples of river water and foodstuff were analyzed by the proposed method,giving results in comformity with the results obtained by AAS.