HPLC and GC-MS screening of Chinese proprietary medicine for undeclared therapeutic substances

Traditional Chinese medicine includes raw medicinal materials and Chinese proprietary medicine (CPM). Despite being of natural origin, toxic effects, adulteration with synthetic therapeutic substances and even deaths had been associated with CPM. There is thus a need to develop analytical technique to rapidly screen for undeclared toxic and therapeutic substances in CPM. In this study, a high performance liquid chromatography-diode-array detection method was developed and used to screen for undeclared therapeutic substances in CPM. An ultraviolet (UV) library of 266 drugs had been compiled. Solute identification was performed by comparing the analytical data (UV spectra, retention time and relative retention time) with those of the 266 standards. Gas chromatography-mass spectrometry was used as a confirmation method. These chromatographic methods had been shown to be selective and reproducible in screening for undeclared drugs in CPM. Using the method developed, 41 CPM samples in seven categories were screened for undeclared therapeutic substances. One anti-asthmatic CPM was found to contain codeine.