Nickel speciation via voltammetric quantification of nickel metal, oxides and salts

A practical speciation method for a solid mixture of nickel species applicable to atmospheric monitoring of Ni0, Ni2+ and NiOx is reported. This involves magnetic extraction of Ni0 to separate it from the water-soluble nickel salts and the insoluble oxides, followed by adsorptive stripping voltammetry to quantify the nickel in each fraction. The separation scheme was validated by using calibration standards and by simulating air-filter samples prepared with authentic nickel products. The recoveries of nickel were Ni0 94–105% and total nickel 95–102%.