Metabolomic database annotations via query of elemental compositions: Mass accuracy is insufficient even at less than 1 ppm

Table 2 Limits for unique formula assignment at certain levels of mass accuracy [ppm]. Above the listed mass ranges multiple formula findings cumulate. The CAS database sometimes reports D instead of H and radicals and ions as substances. Molgen was used with lowest element valence values. Formulas must contain C and H out of elements CHNSOP

		example	example	CAS Hits	CAS Hits	MOLGEN	MOLGEN
ppm	mass range < [Da]	compound 1	compound 2	formula 1	formula 2	formula 1	formula 2
0.1	185.9760	CH2N2O9	C4H11PS3	0	6	7116	1116
0.5	138.0000	C4H2N4S	C3H8O2P2	27	0	247932	353
1	126.0000	C2H8O2P2	C3H2N4S	1	27	2852	24928
2	126.0000	C2H8O2P2	C3H2N4S	1	27	2852	24928
3	126.0000	C2H8O2P2	C3H2N4S	1	27	2852	24928
4	95.9881	C3HN2P	CH4O3S	0	17	522	14
5	95.9881	C3HN2P	CH4O3S	0	17	522	14
6	95.9881	C3HN2P	CH4O3S	0	17	522	14
7	95.9881	C3HN2P	CH4O3S	0	17	522	14
8	95.9881	C3HN2P	CH4O3S	0	17	522	14
9	95.9881	C3HN2P	CH4O3S	0	17	522	14
10	93.9911	CH2O5	C2H6S2	1	22	9	5
20	77.9788	CH2O2S	CH4P2	13	20	9	4

ISSN: 1471-2105