Chelatometric Titration of Mercury (II) with Cupric Diethyldithiocarbamate Chloroform Solution

Since Cu2+ is liberated by the following exchange reaction; (DDC)2+Cu (chloroform) + Hg2+ (aq.)-(DDC)2+Hg (chloroform) + Cu2+(aq.) (here, (DDC) 2Cu designates copper (II) diethyldithiqcarbarnate), He+ can be determined by titrating the liberated Cu3+ with EDTA. After the addition of 10 ml of acetic acid-sodium acetate buffer solution (pH 3.00, 3.27) and 10 ml of 0.01 mol/l (DDC)2+Cu chloroform solution, the sample solution was shaken for about 5 minutes and allowed to stand for about 10 minutes. Then, a 10 ml portion of the aqueous phase was taken for. the chelatometric titration of Cu with 0.002 mol/l EDTA in the presence of PAN as an indicator. When the quantity of Hg2+ was small, all aqueous solutions were taken and titrated with 0.001 mol/l EDTA. Mercury, ranging from 0.0 to 14.85 mg, could be determined. The standard deviation was 0.012 and the variation coefficient was 0.24% at the Hg2+ level of 5.007 mg.