. Author manuscript; available in PMC: 2012 Mar 1.

Published in final edited form as: Int J Mass Spectrom. 2011 Mar 1;300(2-3):99–107. doi: 10.1016/j.ijms.2010.04.006

Table 2.

Summary of the variables and their low/high levels for which used to test the air amplifier performances. Device was tested in 3 different fractional factorial design experiments.

Variable	Level +	Level −	Motivation
Position of vacuum peak	1 mm from ESI inlet	1 mm from MS inlet	Previous experiments showed that these 2 parameters could have a positive impact
ESI Gap	9 mm	6 mm	As no improvement was found at 3mm with the amplifier during previous experiment, larger space was explored
ESI Voltage	3200 V	2800 V	Range that showed good performance in previous experiments
N2 Temperature	100°C	25°C	Hot N2 can improve desolvation
Air amplifier pressure	45 PSI	30 PSI	Amplifier pressure range
Composition	100% H₂0	25% H₂0/75% ACN	Test the hypothesis that the air amplifier can improve desolvation of aqueous solvents.
Air amplifier radial alignment	Centered	0.75 mm offset	Previous experiments performed earlier showed that some
ESI Tip size	100 μm	75 μm	As previous experiments showed no overall signal improvement with air amplifier. This is to test the hypothesis that better results can be obtained with larger tips
Flow	2 μL/min	1 μL/min