Abstract:Four main phenylethylamines in exercise dietary supplements were identified and detected by nuclear magnetic resonance（NMR）.In this study，chromatographic separation or sample pretreatment was not required.Phenylethylamine，synephrine，methyl cinnflin and malt alkaloids were identified from 20 kinds of dietary supplements sold on the market and online.In addition，a nuclear magnetic resonance quantitative method for simultaneous multiplex determination of phenylethylamines was established and verified.Nuclear magnetic resonance spectroscopy（NMR）has been shown to be an effective method for monitoring and detecting nutritional supplements.