Abstract:

A high performance liquid chromatography method for determination of metformin hydrochloride in cosmetics was established. The samples were extracted by water under ultrasonic condition, and then separated on Thermo Acclaim 120 C₁₈ （4.6 mm×250 mm, 5 μm） with methanol-10 mmol/L potassium dihydrogen phosphate solution （containing 1 mmol/L sodium dodecyl sulfate, pH=4.7） （50:50） as mobile phase for isocratic elution. The flow rate was 1.0 mL/min, and the column temperature was 35 ℃. The detection was carried out by a diode array detector with the wavelength of 233 nm. Quantitative analysis was performed by the external standard method. The results show that there is a good linear relationship between the mass concentration of metformin hydrochloride and the peak area in the range of 0.05-2.0 mg/L （r=0.999 9）. The detection limit is 0.30 mg/kg and the quantitative limit is 1.0 mg/kg. The recovery test was conducted by adding standard solution to the blank samples of different types of cosmetics. The recovery rates are in the range of 92.8%-110.0% with the relative standard deviations in the range of 1.96%-6.06% （n=6）. This method has advantages such as simple pretreatment, high accuracy and almost little interference from the matrix. It is suitable for the determination of metformin hydrochloride in cosmetics.

Key words: metformin hydrochloride, cosmetics, high performance liquid chromatography