Table 1.

Chain-cut ions and fragmentation mechanisms for low energy MS/MS spectra obtained via CID of electrospray-generated carboxylate anion [M-H or D]⁻ from the LC peak of a mono-HDHA or O,O-d₂-mono-HDHA.

	-HDHA	Ion m/z	Algorithm	H is from	Fragmentation rearrangemnt	Confirmation by Deuterium-labeling
						labeled- HDHA	ion m/z	Algorithm	D/H is from
cc*	20-	285	20cc+H	20-OH	β-ene	d2-20-	286	20cc+D	20-OD
	17-	245	17cc+H	17-OH	β-ene	d2-17-	246	17cc+D	17-OD
	16-	233	16cc+H	16-OH	γ-ene	d2-16-	234	16cc+D	16-OD
	14-	205	14cc+H	14-OH	β-ene	d2-14-	206	14cc+D	14-OD
	13-	193	13cc+H	13-OH	γ-ene	d2-13-	194	13cc+D	13-OD
	11-	165	11cc+H	11-OH	β-ene	d2-11-	166	11cc+D	11-OD
	10-	153	10cc+H	10-OH	γ-ene	d2-10-	154	10cc+D	10-OD
cm	11-	177	11cm-2H	11-OH,12C	α-H-β-ene	d2-11-	177	11cm-D-H	11-OD, H from 12C
	8-	217	8cm-2H	8-OH,9C	α-H-β-ene	d2-8-	217	8cm-D-H	8-OD, H from 9C
mc	17-	273	17mc-H	16C	α-H-β-ene	d2-17-	274	17mc-H	H from 16C
	16-	261	16mc-H	15C	α-H-β-ene	d2-16-	262	16mc-H	H from 15C
	14-	233	14mc-H	13C	α-H-β-ene	d2-14-	234	14mc-H	H from 13C
	13-	221	13mc-H	13-OH	β-ene	d2-13-	221	13mc-D	13-OD
	11-	193	11mc-H	11-OH	γ-ene	d2-11-	193	11mc-D	11-OD
	10-	181	10mc-H	10-OH	β-ene	d2-10-	181	10mc-D	10-OD
	8-	153	8mc-H	8-OH	γ-ene	d2-8-	153	8mc-D	8-OD
	7-	141	7mc-H	7-OH	β-ene	d2-7-	141	7mc-D	7-OD
	4-	101	4mc-H	4-OH	β-ene	d2-4-	101	4mc-D	4-OD
mm	11-	149	11mm	n.a.**	charge-direct	d2-11-	149	11mm	n.a.
	8-	189	8mm	n.a.	charge-direct	d2-8-	189	8mm	n.a.
	7-	201	7mm	n.a.	charge-direct	d2-7-	201	7mm	n.a.

^*hypothetical homolytic-segment

^**not applicable.