HPLC–UV Chromatographic Methods for Detection and Quantification of Undeclared Withdrawn Synthetic Medications in Counterfeit Herbal Medicines with Confirmation by HPLC–PDA and Mass Spectrometry

Adulteration of herbal medicinal products with synthetic pharmaceuticals remains a serious problem. The purpose of this study is to develop a procedure for determination of some common synthetic adulterants in some herbal remedies available on the market, utilizing a reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection. Herbal medicines for weight loss and another for erectile dysfunction were tested for presence of conceivable adulterants. The weight loss products were discovered to be defiled with the effectively withdrawn drug sibutramine (SIB) and with phenolphthalein (PPH), which has been demonstrated to cause tumors. On the other hand, sildenafil (SLD), a medication contraindicated for patients with heart diseases (sometimes causing serious side-effects with respect to blood pressure), was found in the herbal product for erectile dysfunction. The mobile phase for quantification of sibutramine and phenolphthalein was acetonitrile–potassium hydrogen phosphate buffer (pH 3) adjusted using o-phosphoric acid (40/60 v/v) with detection at 223 nm. Meanwhile, the mobile phase for sildenafil was acetonitrile–potassium hydrogen phosphate buffer (pH 3.2) adjusted using o-phosphoric acid (50/50 v/v) with detection at 230 nm. Presence of the adulterants was confirmed using LC–photodiode array (PDA) and mass spectrometry.