title: Rapid assessment of the illegal presence of 1,3-dimethylamylamine (DMAA) in sports nutrition and dietary supplements using 1H NMR spectroscopy.
abstract: 1,3-Dimethylamylamine (DMAA) is a stimulant that can be found in pre-workout sports nutrition and dietary supplements. This practice is illegal because DMAA is not a safe food ingredient but rather an unapproved medicinal compound due to its pharmacological action. In order to determine the DMAA content in such products, a nuclear magnetic resonance (NMR) spectroscopic method was developed and validated (DMAA was quantified as DMAA-HCl). For quantification, the collective integral from two of the methyl groups of the molecule in the range δ 0.92-0.84 ppm was used. The method was linear over the examined range of 1-21 g/kg (R(2) = 0.9937). The recoveries from spiked concentrations (0.1-6 g/kg) ranged between 85% and 105% (96% on average), with a relative standard deviation (RSD) of 1% for an authentic sample. The detection limit was 0.03 g/kg and the quantification limit was 0.08 g/kg (calculated for 75 mg sample weight). The actual DMAA-HCl content in the sample was quantified using calibration curves (external standardization) or 3,5-dinitrobenzoic acid as single-point internal standard. The developed NMR methodology was applied for the analysis of 16 products, from which 9 samples were found positive (the DMAA-HCl concentration varied between 3.1 g/kg and 415 g/kg). The method can be recommended for routine use in food testing, customs or doping control laboratories.
authors.affiliation: Chemisches und Veterinäruntersuchungsamt (CVUA) Karlsruhe, Weissenburger Strasse 3, 76187, Karlsruhe, Germany; Bruker Biospin GmbH, Silberstreifen, 76287, Rheinstetten, Germany.
authors.forename: Yulia B
authors.initials: YB
authors.lastname: Monakhova
authors.forename: Maren
authors.initials: M
authors.lastname: Ilse
authors.forename: Julia
authors.initials: J
authors.lastname: Hengen
authors.forename: Oliver
authors.initials: O
authors.lastname: El-Atma
authors.forename: Thomas
authors.initials: T
authors.lastname: Kuballa
authors.forename: Matthias
authors.initials: M
authors.lastname: Kohl-Himmelseher
authors.forename: Dirk W
authors.initials: DW
authors.lastname: Lachenmeier
mesh_terms: D000588:Amines / Q000032:analysis*; D002138:Calibration; D019587:Dietary Supplements; D004300:Doping in Sports / Q000379:methods*; D005506:Food Contamination / Q000032:analysis* / Q000331:legislation & jurisprudence; D057230:Limit of Detection; D066244:Proton Magnetic Resonance Spectroscopy
chemical_list: C571979:1,3-dimethylamylamine; D000588:Amines
keywords: DMAA; NMR; dietary supplements; sports nutrition