title: Structural characterization of contaminants in commercial preparations of melatonin by on-line HPLC-electrospray ionization-tandem mass spectrometry.
abstract: Three different commercially available melatonin preparations were analyzed by on-line HPLC-electrospray ionization-tandem mass spectrometry. All three samples contained the same impurities at the approximately 0.1-0.5% level of parent melatonin. Based on accurate mass-HPLC-MS and tandem mass spectrometric analyses, two contaminants (both MH+ = 249) were identified as hydroxylation products of melatonin. One compound (MH+ = 265) was determined to be a C-2 oxidation product of hydroxymelatonin and a group of four regioisomers (MH+ = 477) were identified as melatonin-formaldehyde condensation products. These latter contaminants are structural analogues of the case-associated peak "E" found in L-tryptophan implicated in onset of eosinophilia-myalgia syndrome. The significance of these findings is discussed.
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA. naylor.stephen@mayo.edu
authors.forename: S
authors.initials: S
authors.lastname: Naylor
authors.forename: K L
authors.initials: KL
authors.lastname: Johnson
authors.forename: B L
authors.initials: BL
authors.lastname: Williamson
authors.forename: K
authors.initials: K
authors.lastname: Klarskov
authors.forename: G J
authors.initials: GJ
authors.lastname: Gleich
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004340:Drug Contamination; D006900:Hydroxylation; D013058:Mass Spectrometry / Q000379:methods; D008550:Melatonin / Q000032:analysis* / Q000737:chemistry / Q000592:standards; D015394:Molecular Structure; D009862:Online Systems; D013607:Tablets
chemical_list: D013607:Tablets; D008550:Melatonin