Univariate and Simplex Optimization for the Flow-Injection Spectrophotometric Determination of Copper Using Nitroso-R Salt as a Complexing Agent

A simple colorimetric flow-injection system for the determination of Cu(II) based on a complexation reaction with nitroso-R salt is described. The chemical and FIA variables were established using the univariate and simplex methods. A small volume of Cu(II) was mixed with merged streams of nitroso-R salt and acetate buffer solutions. The absorbance of the complex was continuously monitored at 492 nm. The calibration curve over the concentration range 1.0–7.0 µg ml–1 was obtained. The relative standard deviation for determining 4.0 µg ml–1 Cu(II) was 0.47% (n = 11). The detection limit (3σ) was 0.68 µg ml–1 and the sample throughput was 150 h–1. The validity of the method has been satisfactorily examined for the determination of Cu(II) in wastewater and copper ore samples. The accuracy was found to be high, because the student t-values were calculated to be less than the theoretical values when the results were compared with those obtained by FAAS.