Table I. Summary of mass accuracy analyses of a typical single LC-MS/MS run (replicate 60) and combined analysis of all 60 replicate runs for precursors and products using no mass recalibration, linear mass recalibration, and proportional mass recalibration.

Analysis	Precursors/products	Mass recalibration type	Count	Mean	S.D.
				ppm	ppm
Replicate 60	Precursors	None	1,934	−3.31	0.93
Replicate 60	Precursors	Linear	1,934	−1.68	0.98
Replicate 60	Precursors	Proportional	1,934	+0.77	0.71
Replicate 60	Products	None	23,988	−2.32	0.89
Replicate 60	Products	Linear	23,988	−1.62	0.81
Replicate 60	Products	Proportional	23,990	+0.17	0.67
Combined	Precursors	None	119,184	−1.23	1.54
Combined	Precursors	Linear	119,184	−0.35	1.09
Combined	Precursors	Proportional	119,184	+0.80	0.70
Combined	Products	None	1,622,070	−0.18	1.42
Combined	Products	Linear	1,621,500	−0.10	1.10
Combined	Products	Proportional	1,621,440	+0.16	0.67