Application of multivariate methods to the simultaneous Fourier transform infrared (FT-IR) spectrometric determination of stereo-isomers; Quinine and quinidine

The two stereo-isomers; quinine and quinidine have been determined in their mixtures in the IR region using chemometric multivariate methods, principal component regression (PCR) and partial least squares (PLS). A training set of thirty synthetic binary mixture solutions in the possible combinations containing 0.0-4.0 and 4.0-0.0% w/v quinine and quinidine, respectively in chloroform was used to develop the multivariate calibrations. A validation set containing thirty synthetic binary mixtures of variable ratios in the range of 0.2-4.0 and 4.0-0.2% w/v for quinine and quinidine, respectively in chloroform was used to validate the developed calibrations. The results of analysis of the validation synthetic mixtures were found to be 100.5 +/- 0.44% (R.S.D.%=0.44) and 100.5 +/- 0.38% (R.S.D.%=0.38) for quinine and 100.1 +/- 0.67% (R.S.D.%=0.67) and 100.1 +/- 0.68% (R.S.D.%=0.68) for quinidine using PCR and PLS models, respectively.