Abstract: A method of high performance liquid chromatography-mass spectrometry (HPLC-MS) for the simultaneous determination of 8 illegal synthetic drugs in antihypertensive dietary supplements was developed. The chromatography was performed using a Spherigel C18 column, with the mobile phase of 0.005 mol/L ammonium formate buffer (pH 3.0)-acetonitrile-methanol and cialis as internal standard. In ESI+ mode, the lowest concentration limit of detection (LOD) was 2.5 μg/L and the lowest concentration limit of quantification (LOQ) was 8.3 μg/L, while in ESI- mode, the lowest concentration limit of detection (LOD) was 50 μg/L. The average recoveries were between 63.3%-107.4%. The clonidine, dihydrochlorothiazide, triamterene, metoprolol, phentolamine, chlorthalidone, furosemide and valsartan in the samples were separated well under the optimized conditions. The method was well validated by systematical searching for satisfactory conditions using the experimental designs including precision, repeatability and spiked recovery.

Key words: antihypertensive dietary supplements , illegal synthetic drugs, high performance liquid chromatography-mass spectrometry (HPLC-MS)