硫氰酸盐—吖啶红分光光度法在水相中测定痕量汞

在聚乙烯醇-阿拉伯树胶存在下，汞(Ⅱ)与过量硫氰酸盐形成Hg(SCN)

Spectrophotometric Determination of Trace Mercury in Aqueous Solution with Thiocyanate-Acridine Red

A highly sensitive spectrophotometric method for determination of mercury has been developed,based on mercury in an excess of thiocyanate to form Hg(SCN)2-4,then formation of the 1∶2 ion-association complex of Hg(SCN)2-4 with acridine red in the presence of polyvinyl alcohol-gum Arabic.The molar absorptivity is 3.1×105 L*mol-1*cm-1.The maximum absorbance of ion-association against the reagent blank is at 583 nm.Beer's law is obeyed in the range of 0～9 μg Hg(Ⅱ)/25 mL.The relative standard deviation for the determination of 4.0 μg Hg(Ⅱ)/25 mL is 2.1%(n=9),and the detection limit is 0.35 μg Hg(Ⅱ)/(3σ,n=11).The procedure is relatively simple.Elimination of liminated the interference is achieved by adding the mixed masking agents of potassium fluoride-sulphosalicylic acid-citric acid into sample solution,so the determination has very good selectivity.Trace mercury in aqueous solution has been satisfactorily determined directly by the method.