Development of a liquid chromatography tandem mass spectrometry method for simultaneous determination of eight adulterants in slimming functional foods

A method for simultaneous determination of eight adulterants including two appetite suppressants, two energy expenditure-enhancing drugs, one diuretic and three cathartics in slimming functional foods by high performance liquid chromatography with electrospray ionization–tandem mass spectrometry (HPLC-ESI–MS/MS) was established. After samples were ultrasonically extracted with 70% (v/v) methanol aqueous solution and centrifuged, the components of ephedrine, norpseudoephedrine, fenfluramine, sibutramine, clopamide, emodin, rhein, and chrysophanol in sample solution were separated by a Hypersil Gold column (2.1 mm × 150 mm, 5 μm) using a programmed gradient elution. A mobile phase consisting of 0.02% (v/v) formic acid–ammonium formate buffer solution (pH = 3.50) and methanol was used for elution with a flow rate set at 250 μL/min and column temperature of 25 °C. Qualitative determination was based on characteristic ion pairs and retention time of the targeted compounds using SRM (selective reaction monitoring) mode. Clenbuterol and ibuprofen were internal standards in positive and negative ionization mode, respectively. The internal standard curves were used for quantification measurement. The average recoveries of three different concentrations were from 80.2% to 94.5%. The limits of detection (LODs) were from 0.03 to 0.66 mg/kg (except chrysophanol 1.6 mg/kg). The linear dynamic range covered from 1 to 500 μg/L (except chrysophanol 50–5000 μg/L) for the twelve samples analyzed. Adulterants in four different kinds of slimming functional foods were determined by this developed method, and satisfactory results were obtained. These experimental results showed that, adulteration of sibutramine or/and fenfluramine were the major adulterating components with contents varying from 6.1 to 1.3 × 103 mg/kg and 1.9 to 9.7 × 103 mg/kg, respectively. In addition, three cathartic compounds were detected in six of those tested samples, and ephedrine, norpseudoephedrine and clopamide were not detected in all samples.