Analytical Sciences

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

Boonlom PURACHAT,* Saisunee LIAWRUANGRATH,*  Ponlayuth SOOKSAMITI,** Saowanee RATTANAPHANI,*** and Duang BUDDHASUKH*

*Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50202, Thailand
**Department of Mineral Resources, The Mineral Resources Region 3 (Chiang Mai), 50202, Thailand
***School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand

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 ug ml^-1 was obtained. The relative standard deviation for determining 4.0 ug ml^-1 Cu(II) was 0.47% (n = 11). The detection limit (3sigma) was 0.68 ug 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.

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