Optimization of the gravimetric determination method of nickel as dimethylglyoximate for nickel raw materials

The method parameters of an almost one century old method for analyzing nic kel as dimethylglyoximate were critically examined for the analysis of nick el raw materials and many of the method parameters were observed to have a significant effect on the Ni recovery. Thus, because the Ni precipitation m ethod parameters vary a lot in analytical literature and also in practice, the obtained Ni results by different methods are not comparable. During thi s study it was found that the double precipitation worked out perfectly in eliminating the effects of impurity elements. The residual Ni content in th e filtrates should also be measured to obtain accurate and precise Ni resul ts. In complexing the impurity elements, tartaric acid, stabilized by aceti c acid, turned out to be effective, and when added to the sample solution b efore ammonium addition, the best pH conditions for homogenous Ni precipita tion with dimethylglyoxime were obtained. The optimized Ni determination me thod described was found to be accurate and highly reproducible when tested with Ni concentrates and standard reference materials containing high Ni c oncentrations.