Collision cross-section determination and tandem mass spectrometric analysis of isomeric carotenoids using electrospray ion mobility time-of-flight mass spectrometry.

Carotenoids are natural pigments with provitamin A and antioxidant activities. Biosynthesized in plants as their all-trans isomers, carotenoids isomerize in solution and in humans to multiple cis isomers which can have different bioavailabilities and functions. Since separation and characterization of isomeric carotenoids using high-pressure liquid chromatography (HPLC) or liquid chromatography−tandem mass spectrometry (LC−MS/MS) is time-consuming, the potential for ion mobility mass spectrometry (IM-MS) to resolve and characterize carotenoid isomers rapidly without chromatography was investigated using traveling-wave ion mobility spectrometry on a quadrupole time-of-flight mass spectrometer. The all-trans isomers of lycopene and β-carotene were separated by several milliseconds from the cis-isomers which were detected as partially overlapping peaks. The collision cross-section values of these carotenoid isomers were determined using IM-MS to be 180 and 236 A2 for cis-lycopene and all-trans-lycopene, and ...