Table 1.

Collection of CE_max and corresponding CE_cm-max measured for nine synthetic dabsylated alpha amino acids.

	Compound	PI 1	FI 1	FI	FI	PI	PI
		[M – H]−	ArO−	CEmax	CEcm-max	CEmax	CEcm-max
1	DABS-Gly	362	240	−29.2	−2.10	−29.35	−2.11
2	DABS-Val	403	240	−32.1	−2.09	−32.89	−2.14
3	DABS-Leu	417	240	−35.9	−2.26	-	-
4	DABS-Asp	419	240	−34.5	−2.16	−35.58	−2.23
5	DABS-SMC	421	240	−35.3	−2.20	−32.93	−2.05
6	DABS-Gln	432	240	-	-	−35.60	−2.17
7	DABS-Glu	433	240	−36.1	−2.20	−36.70	−2.23
8	DABS-Met	435	240	−34.0	−2.06	−33.82	−2.05
9	DABS-Trp	490	240	−40.4	−2.18	−35.66	−1.93

¹ PI Precursor ion (m/z, negative ions); FI Fragment ion (m/z, negative ions); NL Neutral Loss (Da). CE_max is the “nominal” value of collision energy; CE_cm-max is the corresponding value of center-of-mass collision energy calculated with Equation (1).