Ammonium 1-pyrrolidine dithiocarbamate (NH4pdtc) was used for a gravimetric determination of Cu(II). Cu(II) ion in the solution was quantitatively precipitated as [Cu(pdtc)2] in the pH range 112, when a small excess of NH4pdtc solution was added. The precipitate was not decomposed at 60°C for 6h in contact with mother liquor, and was stable on heating up to 140°C after filtration. The procedure for the determination of crystalline copper(II) sulfate was following: crystalline copper(II) sulfate (containing 10100mg of copper) was dissolved in 200cm3 water, a 0.1% NH4pdtc solution was added to the solution until precipitation was completed. After the adjustment of pH to 8.09.5, the mixture was allowed to stand at 60°C for 1h. The precipitate was filtrated, washed with hot water, dried at 110°C, and weighed. This method is accurate and precise, e.g., the mean of relative errors and the relative standard deviation obtained for 20mg of copper were 0.1% and 0.1% (n=6), respectively. This method is suitable for standardizing a Cu(II) solution containing no other heavy metal ion.
