Simultaneous catalytic determination of cobalt, nickel, and copper using resazurine sulfide reaction and partial least squares calibration method

The partial least squares calibration method was applied for the kinetic simultaneous determination of the divalent ions of cobalt. nickel and copper based on their catalytic effect on the reaction between resazurine and sulfide. The experimental calibration matrix was designed with 21 samples. The concentrations were varied between 0.1-1.1, 0.1-2.8 and 0.1-1.1 mug ml(-1) for cobalt, nickel and copper, respectively. The cross-validation method was used to select the number of factors. The RMSD for cobalt, nickel and copper were 0.0122, 0.0195 and 0.0179, respectively. Application of the method to artificial samples and several mixtures of standard solutions are performed which gave acceptable results.