Determination of nickel(II) by its influence on the oxidation of 3,3’,5,5’-tetramethylbenzidine with periodate

The negative catalytic action of nickel(II) in the oxidation of 3,3’,5,5’-tetramethylbenzidine with periodate and its positive catalytic effect in the same reaction in the presence of an activator (dimethylglyoxime) have been applied to the development of analytical procedures for the determination of this metal ion, which proved to be more sensitive in the case of a positive catalytic effect (the detection limit of nickel is 10³ times lower).