Simultaneous spectrophotometric determination of phosphate and silicate in different water and soil samples using chemometrics approach

Continuous wavelet transform together with zero-crossing technique was applied to the overlapping visible spectra, as a very simple and accurate method, for the simultaneous determination of phosphate and silicate without any prior separation steps. Daubechies-4, Symlet 8, and Meyer continuous wavelet transforms for signal treatments were found to be suitable. The calibration graphs for estimation of complexes were obtained by measuring the wavelet coefficients at zero-crossing points for silicomolybdenum blue and phosphomolybdenum blue. The constructed calibration functions were tested by analyzing the composition of the different binary mixtures. The experimental data were also analyzed using partial least squares and first-order derivative spectrophotometric method. The proposed method was validated by simultaneous determination of phosphate and silicate in different environmental waters and soil samples. The results of proposed method have been compared with those predicted by partial least squares and standard methods.

Keywords
Continuous wavelet transformation; Derivative method; Partial least squares; Seawater