DISCRETE FOURIER TRANSFORM CONVOLUTED DENSITOMETRIC PEAK RESPONSES FOR THE DETERMINATION OF METHOCARBAMOL IN DIFFERENT PHARMACEUTICAL MIXTURES IN THE PRESENCE OF ITS DEGRADATION PRODUCT

Abstract

Application of chemometrics to the handling of the HPTLC-densitometric response-distance data was used for the determination of methocarbamol in different pharmaceutical mixtures in the presence of its degradation product. The chemometric treatment of the data involves the development of the derivative spectra of the HPTLC-densitometric response-distance data obtained from the separated peaks of three ternary mixtures of methocarbamol and ibuprofen, paracetamol or diclofenac in the presence of Guaifenesin. It also involves the convolution of the derivative curves using 8-points sin xi polynomials (discrete Fourier functions). Chemometric treatment of the densitometric data resulted into the enhancement of the regression equation parameters as well as the enhancement of the accuracy and precision of the prepared synthetic mixtures of the studied drugs. This enhancement is more pronounced in the nonideal case (minor component analysis) where determination of trace amounts of the degradation product corresponding to less than 2% (the pharmacopeial limit) of the intact drug in presence of other mixtures components and background noise. All the proposed chemometric methods can be employed for the assay of the mixtures in their respective dosage forms with good recovery and were compared with HPLC method as a reference method.