Coaxial Electrospray Ionization for the Study of Rapid In-source Chemistry

Abstract

Coaxial electrospray has been used effectively for several dual-emitter applications, but has not been utilized for the study of rapid in-source chemistry. In this paper, we report the fabrication of a coaxial, micro-volume dual-emitter through the modification of a manufacturer's standard electrospray probe. This modification creates rapid mixing inside the Taylor cone and the ability to manipulate fast reactions using a variety of solvents and analytes. We demonstrate its potential as a low-cost, dual-emitter assembly for diverse applications through three examples: relative ionization in a biphasic electrospray, hydrogen-deuterium exchange, and protein supercharging. Graphical Abstract.

In-Source Microdroplet Derivatization Using Coaxial Contained-Electrospray Mass Spectrometry for Enhanced Sensitivity in Saccharide Analysis

“…To date, the contained electrospray ion source has been used to modify source conditions to overcome matrix suppression and study protein folding . Other variations of in-source, dual-emitter platforms have been reported previously for use in applications ranging from polymer coating microdroplets and microemulsions to studying protein structure and isotopic exchange. , However, the contained-electrospray ion source is designed to facilitate both thin film and microdroplet reactions simultaneously, making it a promising approach for in-source chemical derivatization.…”

Exploiting the native inspiratory ability of a mass spectrometer to improve analysis efficiency

“…Besides, the coaxial design of the ESI capillary and sample tube outlet was expected to produce straight and full impacts between the analytes and the charged drops to achieve a high ionization efficiency. [50][51][52] During the experiment, the pressure in the spray chamber of the SAP-ESI source was determined by the pumping speed of the MS instrument and the intake rate of the sample inlet. The former remained constant while the latter could be adjusted by changing the sampling tubing.…”

“…In this experiment, the SAP-ESI device behaved similar to a coaxial ESI source 51 but with a pulsed operating mode. Protonated ions of all analytes, both volatile and non-volatile, can be ionized and appear in the mass spectra.…”

Capillary electrophoresis‐mass spectrometry for intact protein analysis: Pharmaceutical and biomedical applications (2018–March 2023)

“…Moreover, certain reagents could be added to the sheath-liquid for promoting a particular chemical reaction upon mixing with the capillary effluent within the CE-MS interface. This "sheath-flow chemistry" may be used to enhance ionization rates for intact proteins by adding so-called supercharging reagents (e.g., 3-nitrobenzyl alcohol and sulfolane) [212,213]. However, compromised sensitivity may occur due to the dilution effects of the sheath-liquid flow.…”