A Distonic Radical-Ion for Detection of Traces of Adventitious Molecular Oxygen (O-2) in Collision Gases Used in Tandem Mass Spectrometers

作者：Jariwala Freneil B; Hibbs John A; Wei**ecker Carl S; Ressler John; Khade Rahul L; Zhang Yong; Attygalle Athula B^*

来源：Journal of the American Society for Mass Spectrometry, 2014, 25(9): 1670-1673.

DOI：10.1007/s13361-014-0945-5

• Oxygen detection
• Distonic ions
• Radical ions
• Ion-molecule reactions
• Collision gas
• Etoricoxib
• Oxygen adducts

We describe a diagnostic ion that enables rapid semiquantitative evaluation of the degree of oxygen contamination in the collision gases used in tandem mass spectrometers. Upon collision-induced dissociation (CID), the m/z 359 positive ion generated from the analgesic etoricoxib undergoes a facile loss of a methyl sulfone radical [(SO2)-S-aEuro cent(CH3); 79-Da] to produce a distonic radical cation of m/z 280. The product-ion spectrum of this m/z 280 ion, recorded under low-energy activation on tandem-in-space QqQ or QqTof mass spectrometers using nitrogen from a generator as the collision gas, or tandem-in-time ion-trap (LCQ, LTQ) mass spectrometers using purified helium as the buffer gas, showed two unexpected peaks at m/z 312 and 295. This enigmatic m/z 312 ion, which bears a mass-to-charge ratio higher than that of the precursor ion, represented an addition of molecular oxygen (O-2) to the precursor ion. The exceptional affinity of the m/z 280 radical cation towards oxygen was deployed to develop a method to determine the oxygen content in collision gases.

• 出版日期2014-9