SOLID PHASE EXTRACTION-PHOTOMETRIC DETERMINATION OF MERCURY IN TOBACCO WITH A NEW REAGENT p-SULFOBENZYLIDENE RHODANINE

In an acetate medium of pH 3.5 and in the presence of Tween-80,a stable complex was formed by the new color reagent,p-sulfobenzylidene rhodanine (abbreviated as SBDR) with mercury(Ⅱ) having a mole ratio of (R∶Hg) 2 to 1.A solid-liquid extraction was carried out by passing the sample solution containing the SBDR-Hg complex through the solid-phase extraction column (Waters Sep-Pak-C18).The SBDR-Hg complex,which was extracted and enriched on the extraction column,was then eluted from the column with 1.0 mL of absolute alcohol,and its absorbance was measured at 550 nm (the absorption maxima of the complex in alcohol) with a 1 cm micro absorption cell.Molar absorptivity of the color system was found to be 1.05×105L·mol-1·cm-1.Beer′s law was kept in the concentration range of 0 to 4 μg of Hg(Ⅱ) in 50 mL of solution.In its application to the analysis of some tobacco samples,RSD′s (n=5) obtained were less than 2.5%,and recoveries found were in the range of 97%-103%,and the results were in conformity with those obtained by AAS method.