Application of pyrolysis-gas chromatography and hierarchical cluster analysis to the discrimination of the Chinese traditional medicine Dendrobium candidum Wall. ex Lindl.

The pyrogram fingerprints of Dendrobium candidum Wall. ex Lindl. samples from 3 different growing places and 2 other different species were analyzed on the basis of pyrolysis-gas chromatography. An amount of 0.4 mg of sample powder was pyrolyzed in a vertical microfurnace pyrolyzer at 450 °C, and the products were directly introduced into a gas chromatograph equipped with a flame ionization detector or a mass spectrometer. Then, each sample was characterized by the relative peak area of 40 peaks in thus obtained pyrogram. The pyrogram fingerprints of 16 samples from different growing places and species showed good similarity and reproducibility with the relative standard deviations (RSDs) of the retention time less than 0.12% (n = 5) and the RSDs of the relative percent of peak areas less than 3.77% (n = 5). Furthermore, the discrimination of the samples from different growing places and species was achieved by hierarchical cluster analysis via recognizing the 16 × 40 data matrix. Thus, the results proved the Py-GC fingerprint combined with chemometric approach is a simple, rapid and selective method which is suitable for the quality control of the raw materials of herbal medicine.