Metabolite signal identification in accurate mass metabolomics data with MZedDB, an interactive m/z annotation tool utilising predicted ionisation behaviour 'rules'

Table 2 Example default ionisation product mass calculation rules

Name	Charge	xM	Add	RemAt	AddEx	RemEx	Nelec	Rule
[M+]1+	1	1	0				0	Nch = 1
[M+H]1+	1	1	1.007276632		H		-1	Nacc>0 AND Nch = 0
[M+NH4]1+	1	1	18.03382573		NH4		-1	Nacc>0 AND Nch = 0
[M+Na]1+	1	1	22.98922127		Na		-1	Nacc>0 AND Nch = 0
[M+K]1+	1	1	38.96315853		K		-1	Nacc>0 AND Nch = 0
[M-NH2+H]1+	1	1	-15.0119958	NH			-1	Nnhh>0 AND Nch = 0
[M-CO2H+H]1+	1	1	-44.9982027	CO2			-1	Ncooh>0 AND Nch = 0
[M-H2O+H]1+	1	1	-17.0032881	OH			-1	Noh>0 AND Nch = 0
[M-]1-	-1	1	0				0	Nch = -1
[M-H]1-	-1	1	-1.00727663			H	1	Ndon>0 AND Nch = 0
[M+Na-2H]1-	-1	1	20.97466801		Na	H2	1	Ndon>1 AND Nacc>0 AND Nch = 0
[M+Cl]1-	-1	1	34.96940111		Cl		1	Nacc>0 AND Nch = 0
[M+K-2H]1-	-1	1	36.94860527		K	H2	1	Ndon>1 AND Nacc>0 AND Nch = 0

AddAt: formula of the atoms to be added to the molecular formula of one M.
RemAt: formula of the atoms to be removed to the molecular formula of one M.
AddEx: formula of the atoms to be removed to obtain the final IP molecular formula
(e.g. non covalently bound salts and solvent).
RemEx: formula of the atoms to be removed to obtain the final IP molecular formula
(e.g. non covalently bound salts and solvent).
Nelec: number of electron to be added when calculating isotopic patterns (mass_e = 0.0005484).
Rule: set of rules to be applied on one M.
Nacc: number of H-bond acceptor in M.
Noh: number of -OH groups in M.
Ncoo: number of -COO^- groups in M.
Naci: number of acidic H in M.
Nch: number of charges in M.
Ndon: number of H-bond donor in M.
Ncooh: number of -COOH groups in M.
Nnhh: number of -NH2 groups in M.
Nbas: number of basic O^- in M.

ISSN: 1471-2105