Liquid chromatography-quadrupole time of flight mass spectrometric method for targeted analysis of 111 nitrogen-based compounds in weight loss and ergogenic supplements

• Published in: Journal of pharmaceutical and biomedical analysis 2019-09, Vol.174, p.305-323
• Main Authors: Avula, Bharathi, Bae, Ji-Yeong, Chittiboyina, Amar G., Wang, Yan-Hong, Wang, Mei, Khan, Ikhlas A.
• Format: Article
• Language: English
• Subjects: Alkaloids; Amines; Amines - analysis; Anti-Obesity Agents - analysis; Central Nervous System Stimulants - analysis; Chromatography, Liquid - methods; Dietary supplements; Dietary Supplements - analysis; Electrons; Gas Chromatography-Mass Spectrometry - methods; Ions; Limit of Detection; Nitrogen Compounds - analysis; Performance-Enhancing Substances - analysis; Reproducibility of Results; Solvents; UHPLC-QToF
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2019.05.066

•A validated UHPLC-QToF-MS method was developed for the simultaneous analysis of 111 stimulants, anorectics and other active components.•The method was applied to the analysis of twenty-seven weight loss and pre-workout dietary supplements.•Two-thirds of the supplements contained compounds that were not listed on the label. These include several phenethylamine analogs.•44% of the analyzed supplements did not contain at least 1–10 claimed ingredients and 67% of the supplements contained un-claimed ingredients.•Lack of quality control in 27 analyzed dietary supplements. The use of supplements for weight loss and in sports as pre-workout (ergogenic) products is widespread. Many of these supplements were found to contain active components, which were not claimed on the products labels. A validated liquid chromatography high-resolution mass spectrometry quadrupole time-of-flight (LC-QToF-MS) method was developed for the simultaneous analysis of 111 amine-based compounds belonging to ergogenics, anorectics and other active components including phenethylamines (amphetamines, ephedrines), sibutramine or yohimbine. This method involves the detection of [M+H]+ ions and the separation was achieved using a C18 column, water/acetonitrile gradient as the mobile phase. The method was validated for linearity, repeatability, accuracy, stability, system suitability, limits of quantification (LOQ) and limits of detection (LOD). The limits of detection were in the range from 0.001-0.5 μg/mL. The validated method was applied to the analysis of twenty-seven weight loss and ergogenic dietary supplements. Two-thirds of the supplements contained compounds that were not listed on the product’s label. These include several phenethylamines (PEA) such as demelverine, hordenine, N, N-dimethyl-phenethylamine, synephrine, N-methyl-β-phenethylamine, and methylsynephrine. In addition, the PEA mimics such as dimethylamylamine, dimethylbutylamine other stimulants including fursultiamine, evodiamine, phenibut and theophylline were also observed. One or more of the ingredients listed on the labels were not detected in forty-four percent of the products analyzed. Positive identification was based on retention time, accurate mass and fragment ions in comparison with the respective reference standards. Development of such methods is anticipated to be of aid to regulatory agencies for the identification of undeclared exogenous components that are found in many dietary supplement products.