[Pyrolysis-gas chromatographic fingerprints with hierarchical cluster analysis for Dendrobium candidum Wall. ex...

The pyrogram fingerprints of Dendrobium candidum Wall. ex Lindl. from different regions were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and compared with hierarchical cluster analysis. The effect of pyrolysis temperature on the fingerprint was examined by evolved gas analysis, and then 450 degrees C was selected as the optimized pyrolysis temperature. An amount of 0.4 mg of raw drug powder was pyrolysed in a vertical microfurnace pyrolyzer, and the products were directly introduced into a gas chromatograph equipped with a flame ionization detector (FID) and a fused-silica capillary column (30 m x 0.25 mm x 0.25 microm). The pyrogram fingerprints of 10 samples from different regions showed a high similarity and a good reproducibility with the relative standard deviations (RSDs) of the retention times less than 0.33% and the RSDs of the relative peak areas less than 4.8%. Therefore, each sample was characterized by the peak area of 31 peaks in each pyrogram and these peaks were employed for hierarchical cluster analysis. Furthermore, the discrimination of the sample from different regions was achieved by hierarchical cluster analysis via recognizing the 10 x 31 data matrix. Thus, the results proved it is a simple, rapid and accurate method suitable for the quality control of the traditional Chinese medicines.