Simultaneous Spectrophotometric Determination of Heavy Metal Ions Using Several Chemometrics Methods: Effect of Different Parameters of Savitzky-Golay and Direct Orthogonal Signal Correction Filters

Abstract

<em>Direct orthogonal signal correction(DOSC) and Savitzky-Golay filters (SGF) were applied as preprocessing methods on the original and first derivative absorbance data. Principle component regression (PCR), partial least squares (PLS) and iterative target transformation factor analysis (ITTFA), were used in spectrophotometric simultaneous determination </em><em>of heavy divalent metal ions, lead, zinc,</em><em>mercury and cadmium,</em><em>using 4-(2-pyridylazo) resorcinol (PAR) as metallochromic indicator. The optimum values of the parameters for DOSC and SGF were obtained according to REP, R² and RMSEP functions for calibration and prediction sets. The concentration for Hg²⁺, Pb²⁺, Zn²⁺ and Cd²⁺ ions in calibration set were varied between 0 - 12.24, 0 - 9.81, 0 - 0.87 and 0 - 3.96 ppm, respectively. The experimental calibration set was composed of 35 sample solutions and the 7 solutions as prediction set using a simple lattice (4,4) mixture design. The absorption spectra were recorded from 450 to 600 nm and absorbance data were autoscaled. The effect of pH on the sensitivity and selectivity was studied in the rang</em><em>e</em><em> of 1.00 - 11.00 and pH=7.50 was chosen according to net analyte signal (NAS) as a function of pH</em><em>.</em>