A combination of molecular probe-tandem electrospray ionization mass spectrometry: a technique for tracing structural changes in phospholipid hydroperoxides.

An ethyl-labeled phosphatidylcholine hydroperoxide (PC-OOH/Et 2) was synthesized as a molecular probe for naturally occurring PC-OOH 1. Applying the precursor ion scan mode in tandem ESI mass spectrometry at m/z 198, a signal of the PC-OOH/Et 2 alone could be selectively detected even in the presence of a large excess of a complex mixture of phospholipids in the blood. Furthermore, molecular species that formed from PC-OOH/Et 2 by its degradation in the blood were also observed in the same spectrum. Since the molecular probe-and-mass spectrometry-assisted analytical method presented herein requires no separation process by HPLC or TLC and is speedy, requiring less than 1 h, it may be useful in lipid analysis.