, vol. 140: Elsevier, pp. 334-343, 2015.
Five signal processing techniques were applied to ratio spectra for quantitative determination of bisoprolol
(BIS) and hydrochlorothiazide (HCT) in their binary mixture. The proposed techniques are Numerical
Differentiation of Ratio Spectra (ND-RS), Savitsky–Golay of Ratio Spectra (SG-RS), Continuous Wavelet
Transform of Ratio Spectra (CWT-RS), Mean Centering of Ratio Spectra (MC-RS) and Discrete Fourier
Transform of Ratio Spectra (DFT-RS). The linearity of the proposed methods was investigated in the range
of 2–40 and 1–22 lg/mL for BIS and HCT, respectively. The proposed methods were applied successfully
for the determination of the drugs in laboratory prepared mixtures and in commercial pharmaceutical
preparations and standard deviation was less than 1.5. The five signal processing techniques were compared to each other and validated according to the ICH guidelines and accuracy, precision, repeatability
and robustness were found to be within the acceptable limit.