SIMULTANEOUS DETERMINATION OF IRON, COBALT, NICKEL AND COPPER BY UV-VISIBLE SPECTROPHOTOMETRY WITH MULTIVARIATE CALIBRATION

A method for the simultaneous spectrophotometric determination of the divalent ions of iron, cobalt, nickel and copper based on the formatio n of their complexes with I,5-bis(di-2-pyridylmethylene) thiocarbonohy drazide (DPTH) is proposed. The resolution of quaternary mixtures of t hese metallic ions was accomplished by several chemometric approaches. A comparative study of the results obtained for simultaneous determin ations in mixture by using principal component regression (PCR) and pa rtial least-squares regression (PLS-1 and PLS-2) for absorbance, first -derivative and second-derivative data is presented. In general, the b est recovery values are obtained by the PLS-2 method for absorbance da ta. This procedure allows the simultaneous determination of the cited ions in alloys and biological materials Good reliability of the determ ination was proved. (C) 1998 Elsevier Science B.V. All rights reserved .