Fundamental And Applied Studies Of An Ambient Ionization Technique: Continuous Flow-extractive Desorption Electrospray Ionization - Mass Spectrometry

Abstract

Continuous flow extractive desorption electrospray ionization (CF-EDESI) is a novel ambient ionization technique that was developed to help analyze samples from non-ESI-friendly solvents, manipulate protein charge states, and couple to a flowing sample solution stream. CF-EDESI is performed by introducing a sample solution through a hypodermic needle set orthogonal to an on-axis electrospray ionization source. Samples dissolved in non-ESI-friendly solvents such as hexanes, ethyl acetate etc. can be successfully detected in CF-EDESI which then makes it an attractive detection technique for normal phase separation. Additionally, introducing samples separated from electrospray has provided freedom to optimize both the sample solvents and spray solvents. Additives such as acetic acid, sulfolane, m-nitrobenzyl alcohol were used in spray solvents to manipulate the protein charge state, which also minimized the post column band broadening for separations when coupled with separation. Besides, ammonium acetate additive in spray solvents can greatly reduce the sodium adducts in lipid analysis from MTBE.