Determination of Minoxidil Illegally Adulterated in Cosmetics by HPLC

OBJECTIVE To establish a specific method for the determination of minoxidil illegally adulterated in cosmetics. METHODS The separation and analysis was performed on a Diamonsil C18 column(4.6 mm×250 mm, 5.0 μm). The mobile phase consisted of methanol-water-acetic acid glacial (730∶270∶10)(contained 0.3% of dioctyl sodium sulfosuccinate and adjusted pH to 3.0 with perchloric acid). The flow rate was 1.0 mL·min^-1 and detected at 280 nm. RESULTS The assay linearity of minoxidil was confirmed over the range of 1-100 μg·mL^-1, and the detection limit was 5 μg·g^-1. The average recovery was 100.4%. CONCLUSION The method is proved to be accurate, specific, sensitive and convenient. Therefore, it can be used to determinate minoxidil illegally adulterated in hair cosmetics.