Determination of cobalt at low levels in silicate rocks by atomic absorption spectrometry using a continuous on-line precipitation-dissolution procedure based on 1-nitroso-2-naphthol

Abstract

A continuous pre-concentration flame atomisation atomic absorption spectrometric method for the determination of cobalt by precipitation with 1-nitroso-2-naphthol is proposed. The sample treatment, dissolution of the tris(1-nitroso-2-naphthalato)cobalt(III), optimisation of analytical variables and measurable concentration levels are discussed. Several calibration graphs were used for the determination of Co^II in the range 1–180 ng ml^–1 with a sampling frequency of between 4 and 40 h^–1 and a relative standard deviation of between 2.5 and 3.0%. The proposed method was successfully applied to the determination of Co at the µg g^–1 level in silicate rocks.