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1451487 
Journal Article 
Tandem mass spectrometry of bilin tetrapyrroles by electrospray ionization and collision-induced dissociation 
Quinn, KD; Nguyen, NhuQT; Wach, MM; Wood, TD 
2012 
1 
Rapid Communications in Mass Spectrometry
ISSN: 0951-4198
EISSN: 1097-0231 
26 
16 
1767-1775 
22777778 
WOS:000306279800006 
RATIONALE Bilins are metabolic products of hosts and
bacteria on porphyrins, and are markers of health state and human waste contamination. Although
bilin tandem mass spectrometry reports exist, their fragmentation behavior as a function of
structure has not been compared, nor has fragmentation been examined as a function of collision
energy. METHODS The fragmentation of bilins generated by positive ion mode electrospray
ionization is examined by collision-induced dissociation (CID). CID on a quadrupole ion trap and
on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer as a function of
collision energy is compared. Methyl esterification was used to deduce which product ions contain
the inner pyrrole rings. FT-ICR high mass accuracy measurements were used to determine the
formulas of the resultant product ions. RESULTS The central carbon's bonding to the inner
pyrrole rings influences fragmentation. Bilirubin is unique because fragmentation adjacent to the
central methylene group between innermost rings predominates, and loss of a terminal pyrrole is
observed only with helium collision gas. The other bilins lose the terminal pyrroles first; as
CID energy is increased, additional fragmentation due to neutral losses of small molecules such
as H2O, CO, CO2, and methanol occurs. CONCLUSIONS Based on these observations, fragmentation
schemes for the bilins are proposed that are strongly dependent on the molecular structure and
collision energy; only bilirubin fragmentation is influenced significantly by the collision gas
used. This report should have value in identification of this class of molecules for biomarker
detection. Copyright (C) 2012 John Wiley & Sons, Ltd. 
IRIS
• Methanol (Non-Cancer)
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