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

Authors: AVULA, BHARATHI - University Of Mississippi; BAE, JI-YEONG - University Of Mississippi; CHITTIBOYINA, AMAR - University Of Mississippi; WANG, YAN-HONG - University Of Mississippi; WANG, MEI - University Of Mississippi; KHAN, IKHLAS - University Of Mississippi

Submitted to: Journal of Pharmaceutical and Biomedical Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2019
Publication Date: 5/31/2019
Citation: Avula, B., Bae, J., Chittiboyina, A.G., Wang, Y., Wang, M., Khan, I.A. 2019. Liquid chromatography-quadrupole time of flight mass spectrometric method for targeted analysis of 111 nitrogen-based compounds in weight loss and ergogenic supplements. Journal of Pharmaceutical and Biomedical Analysis. 174:305-323. https://doi.org/10.1016/j.jpba.2019.05.066.
DOI: https://doi.org/10.1016/j.jpba.2019.05.066

Interpretive Summary: • A validated liquid chromatography high-resolution mass spectrometry quadrupole time-of-flight (LC-QToF-MS) method was developed for the simultaneous analysis of 111 stimulants, anorectics and other active components. The method was validated in terms of linearity, accuracy, selectivity, limits of detection (LOD), limits of quantification (LOQ), and precision. • 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 including demelverine, hordenine, N, N-dimethyl-phenethylamine, synephrine, N-methyl-B-phenethylamine, and methylsynephrine. • 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 developed method will be useful for the determination and confirmation of unknown molecules, contaminants or adulterants that might be expected to be present in weight loss and sports supplements via targeted or non-targeted approach.

Technical Abstract: 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 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 anorectics and other active components including phenethylamines (amphetamines, ephedrines) or 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 label. These include several phenethylamines (PEA) such as demelverine, hordenine, N, N-dimethyl-phenethylamine, synephrine, N-methyl-B-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 supplements.