Determination of nickel in rocks by use of a continuous precipitation–preconcentration system coupled on-line to a flame atomic absorption spectrometer

Abstract

A rapid, accurate and precise method is described for the determination of Ni at the microgram per gram level in silicate rocks. The method is based on the continuous precipitation of Ni with 1-nitroso-2-naphthol and dissolution of the complex formed in ethanol. The sensitivity of Ni determination is greatly enhanced by the presence of hydrogen peroxide. The metal can be preconcentrated 50-fold using a 10 ml volume of sample, with a sampling frequency of 15–20 h^–1 and a relative standard deviation of 3.2% at 50 µg l^–1 of Ni. Tiron was used to increase the tolerated amount of Fe up to an Fe:Ni ratio of 7500:1. Six reference silicate rocks were analysed for Ni to test the accuracy of the proposed method; the results were all consistent with the compiled values.