Ratio spectra-continuous wavelet transform and ratio spectra-derivative spectrophotometry for the quantitative analysis of effervescent tablets of vitamin C and aspirin

Abstract

Simultaneous spectrophotometric analysis of tablets and binary mixtures containing vitamin C (VC) and aspirin (ASP) with overlapping spectra was performed by ratio spectra-continuous wavelet transform (RS-CWT) and ratio spectra-derivative spectrophotometry (RS-DS). In the application of RS-CWT and RS-DS to the simultaneous analysis of VC and ASP no separation step was considered. The basis of RS-CWT and RS-DS approaches is the transformation and the derivation of the ratio spectra of the related compounds and their samples. Calibration graphs in the linear concentration range 4-20 pglmL for both compounds were obtained by measuring the CWT and first derivative amplitudes at 260.8 nm for VC and 234.6 nm for ASP in the BIOR-CWT spectra and at 256.0 nm for VC and 230.7 nm for ASP in the first derivative of ratio spectra, respectively. Both methods were tested by using the synthetic mixtures and standard addition technique, and were applied to the simultaneous determination of VC and ASP in commercial effervescent tablets and a good coincidence was reported for experimental results obtained by the proposed RS-CWT and RS-DS.