Simultaneous Automatic Determination of Trace Amounts of Copper and Cobalt by Use of a Flow-through Sensor and First-derivative Spectrometry

Abstract

A straightforward method for the simultaneous determination of cobalt and copper in binary mixtures by use of a diode-array detector accommodated in a flow-through spectrophotometric sensor and pyridoxal-4-phenylthiosemicarbazone as reagent is proposed. The coloured complexes formed give extensively overlapped spectra that can only be resolved from their first derivative. The method relies on integrated preconcentration and detection in the flow cell that allows a high sensitivity in the determination of the two metal ions with detection limits of 0.03 µg ml ^{- 1} for both and an RSD (n = 11; P = 0.05) of 2.0% for cobalt and 0.9% for copper, at a rate of 36 samples h ^{- 1} . The method was applied to the determination of cobalt and copper in several steel samples.