Detection and determination of phenformin in Chinese medicinal capsules by GC-MS and HPLC

Phenformin was prohibited by the ROC Department of Health in 1978. In this investigation, a GC-MS was used for the detection of phenformin in herbal preparation produced in Mainland China followed by determination by HPLC. For GC-MS, a HP-5MS capillary column was used. The initial column temperature was at 100 degreesC for 2 min, ramping 10 degreesC/min to 280 degreesC, then holding at 280 degreesC for 15 min. Ionization source temperature was at 230 degreesC, and 70 eV electron impact mode was employed. HPLC was performed on a Cosmosil 5C18 AR (5 cm x 4.6 mm), and a mu Bondpak phenyl (30 cm x 3.9 mm) column using 0.01 M potassium dihydrogenphosphate (pH 6.55) - acetonitrile (60:40, v/v) as eluent, with flow rate at 1.0 mL/min and detection wavelength set at 235 nm. Metformin was used as the internal standard. The interday and intraday precisions were less than 1.6%. The limit of detection and the limit of quantitation were 0.065 mug/mL and 0.20 mug/mL, respectively. The spike recovery was 102.7%. The average content of phenformin in the preparation was 3.45 mg per capsule.