Table 1. Candidate Structures Proposed for Zeaxanthin [M]⁺ and Lutein [M – 18]⁺ Carotenoids^a.

		theoretical in N2
carotenoid isomer		K0 (cm2/(V s))	CCS (Å2)	ΔE (kJ mol–1)	experimental IMS peak (Å2)
zeaxanthin [M]+ and [M+H]+	all-trans	0.6608	327		327 - A
	15-cis	0.6656	325	19	325 - B
	13-cis	0.6655	325	28	325 - B
	9-cis	0.668	324	15	323 - C
	9,13′-di-cis	0.6753	320	22	318 - D
lutein [M-18]+	all-trans	0.6709	323		322 - A
	9-cis	0.6832	317	5	317 - C
	9,13′-di-cis	0.6883	315	3	315 - D

^aMore details in the supplemental material. Energies were calculated relative to the most abundant isomer. Experimental CCS error is <5 Ų.