Simultaneous determination of ternary drug mixtures using square wave polarography subjected to non-parametric and chemometric peak convolution

This manuscript discusses the application of chemometrics to the polarographic response data. It deals with convolution of signals using orthogonal polynomials in the determination of multi-component mixtures. The method was found beneficial in the resolution of partially overlapping square wave polarographic peaks of ternary mixtures of isoniazid (ISN), rifampicin (RIF) and pyrazinamide (PYR), in Britton Robinson buffer pH 7.0. The square wave polarographic analysis data were processed by orthogonal functions and the first-derivative methods. The procedure was successfully applied to the simultaneous determination of the three drugs in their pharmaceutical preparations and biological fluids. This work also compares the application of Theil's method, a non-parametric regression method, in handling the response data, with the least-squares parametric regression method, which is considered the de facto standard method used for regression. Theil's method was found to be superior to the method of least squares as it assumes that errors could occur in both x- and y-directions and they might not be normally distributed. In addition, it could effectively circumvent any outlier data points.