Simultaneous Determination of Trace of Ca(II) and Mg(II) in Water and Pharmaceutical Products by Partial Least Squares (PLS) Method

The quantitative prediction ability of partial least squares method applied to conventional and derivative UV-VIS absorption spectra is tested. This method is based on the complexation reaction between Ca(II) and Mg(II) with bromopyrogallol red (BPR) ligand in a micellar medium (Tween 80) adjusted by buffer solution, containing sodium hydroxyd (NaOH 0.1M)/ sodium tetraborate (Na₂B₇O₄, 10H₂O 0.05M), to pH10. In the  numerical method, a training set was prepared by using 14 samples containing these metals simultaneously in the calibration range. The proposed methods were validated by using synthetic binary mixtures and applied to the simultaneous determination of  Ca(II) and Mg(II) in multivitamins, physiological serum and commercial drinking water samples. The results were compared each other, the derivative mode gave better results in all cases. We concluded that the application of differentiation techniques prior to PLS algorithms could be advantageous in the cases of high spectral overlapping.