The Application of Dynamic Time Warping to the Quality Evaluation of Radix Puerariae thomsonii: Correcting Retention Time Shift in the Chromatographic Fingerprints.

The application of dynamic time warping (DTW) to the correction of retention time shift in chromatographic fingerprints of Radix Puerariae thomsonii (RPT) was studied. The fingerprints of 27 RPT samples were established with their entire chromatograms. Because there is retention time shift in the obtained fingerprints, the quality of these samples cannot be correctly evaluated by applying similarity estimation and principal component analysis (PCA) to the unaligned fingerprints. Hence, the fingerprints were aligned by using DTW method. After alignment, the retention time shift was corrected satisfactorily and the quality of these RPT samples was correctly evaluated. It is demonstrated that DTW is a practical method for aligning the chromatographic fingerprints of RPT samples. The combination of similarity estimation, PCA and DTW is shown to be a promising method for evaluating the quality of herbal medicines.