Rapid detection of the metformin illegally added of in TCM and health food by TLC-IR.

Based on TLC-IR, the study established an effective method for rapid detection of metformin illegally added in hypoglycemic traditional Chinese medicine and health food products. 12 batches of hypoglycemic traditional Chinese medicine and health products were purchased in the pharmacy, which were produced by different manufacturers. TLC was used to separate metformin and phenformin for preliminary identification from. IR was applied to further identification and HPLC method was used to verify the experimental results of TLC-IR. TLC developing solvents was petroleum ether-methanol-glacial acetic acid (5:12:0.5) and the stationary phase was silica gel prefabricated GF254 plate. IR used KBr pellet pressing method with a resolution of 4cm-1 and scanned 64 times. The column for HPLC analysis was SinoChrom ODS-BP 5 µm (4.6mm *250mm) and the injection volume was 20μL. The detection wavelength was 234nm. The flow rate was 1ml•min-1. Metformin and phenformin were significantly separated under the TLC condition. Joint identification by TLC-IR, none of metformin and phenformin were identified in the hypoglycemic traditional Chinese medicine. Phenformin was detected in two kinds of health products while metformin was identified in one kind of health food. The result of HPLC was consist with TLC-IR. The established TLC-IR method was simple, rapid and selective, which was suit to apply in the identification of metformin illegally added in hypoglycemic traditional Chinese medicine and health food products.