Principal Component Analysis-based Strategy to Identify the Presence of Tissue-Cultured and Wild-Type Dendrobium officinale and Dendrobium moniliforme in a Commercial Preparation

A principal component analysis-based two-dimensional correlation infrared spectroscopy technique combined with tri-step infrared macro-fingerprinting was explored to discriminate 1–4 years of tissue-cultured from wild-type Dendrobium officinale and Dendrobium moniliforme. The results showed that although speciation and origins of the Dendrobium samples could be differentiated by Fourier-transform infrared spectroscopy and second derivative infrared spectroscopy spectra, it is quite difficult to identify the age of Dendrobiums. In the further principal component analysis-based two-dimensional correlation infrared analysis, the range 1390–1230 cm^-1 and 1180–1020 cm^-1, in which the auto-peaks attributed a major variance ratio, were chosen to discriminate different cultivated years of Dendrobiums. Different ages of D. officinale and D. moniliforme showed their characteristic auto-peaks and cross-peaks with different peak positions and intensity in these two range. Our research indicated that principal component analysis-based strategy combined with tri-step infrared macro-fingerprint is suitable to rapidly discriminate the different ages of Dendrobiums with species and origins.