Table 2.

Differences in the relative abundances of the molecular ions (as percent of the base peak in each mass spectrum) comparing 80 QCEIMS spectra in the 12 subclasses of purines and pyrimidines to molecular ions of NIST 17 experimental spectra.

	Mol ID	Molecular Weight	Experimental Abundance (%)	QCEIMS Abundance (%)	Abundance Difference (%)	Average Difference (%)
Pyrimidines	5	126	82	32	−50	30.3%
	16	140	64	98	+34
	17	140	100	71	−29
	19	141	100	91	−9
	41	154	100	65	−35
	42	154	80	57	−23
	43	155	100	97	−3
	81	170	100	41	−59
Xanthines	39	153	94	100	+6	39.8%
	75	168	27	100	+73
	100	180	100	57	−43
	106	181	25	67	+42
	132	195	14	49	+35
Hypoxanthines	28	150	100	83	−17	30%
	31	150	70	100	+30
	52	164	100	57	−43
Lumazines	65	166	2	100	+98	42%
	96	180	100	64	−36
	121	192	100	79	−21
	128	194	100	87	−13
Quinazoline- diones	86	177	60	26	−34	19.7%
	115	190	100	87	−13
	120	192	100	88	−12
Remycins	92	179	66	19	−47	37.5%
	105	181	1	49	+48
	123	193	24	40	+16
	125	193	63	27	−36
	126	193	100	31	−69
	147	207	14	23	+9
Pyridopyrimidine-(1H,3H)-diones	47	163	100	82	−18	20.4%
	50	163	88	100	+12
	116	191	100	84	−16
	117	191	100	54	−46
	118	191	100	90	−10
Others	70	167	11	89	+78	62.3%
	74	168	100	59	−41
	80	170	100	21	−79
	122	192	49	100	−51