Analysis of HPLC fingerprints: discrimination of raw and processed Rhubarb samples with the aid of chemometrics

Chromatographic fingerprints of raw, wine-treated and braised rhubarb samples were obtained by liquid chromatography with a diode array detector (LC-DAD). Eight LC peaks were selected for fingerprint analysis, and six compounds were identified as gallic acid, emodin, chrysophanol, palmidin, rhein glucoside and desoxyrhaponticin. A data matrix of the chromatographic fingerprints from the three types of sample was submitted to principal component analysis (PCA) and this indicated that the three types of rhubarb were distinguished in the PC1versusPC2 space. Training, verification and prediction data sets of the three types of HPLC fingerprint were processed successfully by chemometrics data classification methods, K-nearest neighbor (KNN), linear discriminant analysis (LDA) and least squares support vector machines (LS-SVM), and these types of rhubarb sample were classified satisfactorily.