Examination of structurally selective derivatization of vitamin D3 analogues by electrospray mass spectrometry

✍ Scribed by Andrew S. Weiskopf; Paul Vouros; Jack Cunniff; Ernst Binderup; Fredrik Björkling; Lise Binderup; Maria-Christina White; Gary H. Posner

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 236 KB
• Volume: 36
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.105

✦ Synopsis

The structural specificity of vitamin D derivatization by PTAD (4-phenyl-1,2,4-triazoline-3,5-dione) was probed using synthetic analogues and ion trap mass spectrometry. EB 1089, a vitamin D(3) analogue which contains a second site for Diels--Alder cycloaddition on its side-chain, allowed the examination of derivatization modes and comparisons of ion fragment structures. The origins of a PTAD-vitamin D(3) ion fragment, commonly used in metabolite characterization and quantitation of vitamin D(3) analogues (m/z 314), were established; ion trap mass spectrometry revealed that the PTAD comprises a portion of this diagnostic fragment, and is not lost by a retro-Diels--Alder step. Furthermore, the unique structure of the EB 1089 side-chain also permits facile determination of its side-chain metabolism. Use of PTAD derivatization and detection of metabolite-specific ion fragments identify hydroxylation at the end of the EB 1089 sidechain. It is believed that the results from these studies provide a clearer understanding of the mass spectrometry of triazolinedione derivatives, not only in the specific case of EB 1089, but also in their application to other vitamin D compounds.