Table 2. Sensitivity and Specificity of Predicting the Presence of Substructures from Common Neutral Losses Using the NIST11 MS/MS Library.

compound class	neutral loss	mass (Da)	sensitivity (%)	specificity (%)
aliphatic primary amines	NH3	17.027	69.5	85.5
carboxylic acids	H2O	18.011	84.9	42.9
aldehydes	CH2O	30.011	44.4	94.8
methyl esters	CH3OH	32.026	72.0	95.6
thiol	H2S	33.988	66.0	98.0
chlorides	HCl	35.977	15.4	93.2
N-acetyl derivatives	CH2CO	42.011	69.0	89.7
nitroaromatics	NO2	45.993	23.5	90.7
carboxylic acids	HCOOH	46.005	34.8	78.4
methyl sulfides	CH4S	48.003	33.6	97.7
α,β-unsaturated acids	CH3COOH	60.021	53.8	82.7
phosphate group	H3PO4	97.977	42.9	98.0
cysteine conjugates	C3H7NO2S	121.020	33.0	98.2
hexoside	C6H10O5	162.053	80.0	94.6