Issue 17, 2023

Tuning oxidative modification by a strong electric field using nanoESI of highly conductive solutions near the minimum flow rate

Abstract

Oxidative modification is usually used in mass spectrometry (MS) for labeling and structural analysis. Here we report a highly tunable oxidation that can be performed in line with the nanoESI-MS analysis at the same ESI emitter without the use of oxidative reagents such as ozone and H2O2, and UV activation. The method is based on the high-pressure nanoESI of a highly conductive (conductivity >3.8 S m−1) aqueous solution near the minimum flow rate. The ion source is operated under super-atmospheric pressure (0.5 MPa gauge pressure) to avoid the contribution of electric discharge. The analyte at the tip of the Taylor cone or in the emitter droplet can be locally oxidized in an on-demand manner by varying the nanoflow rate. With an offline nanoESI, the degree of oxidation, i.e., the average number of incorporated oxygen atoms, can be finely tuned by voltage modulation using spray current as the feedback signal. Oxidations of easily oxidized residues present in peptides/proteins and the double bonds of the unsaturated phosphatidylcholine occur at low flow rate operation (<5 nL min−1) when the electric field at the tip of the Taylor cone and the initially produced charged droplet reaches approximately 1.3 V nm−1. The oxidized ion signal responds instantaneously to changes in flow rate, indicating that the oxidation is highly localized. Using isotope labeling, it was found that the incorporated oxygen primarily originates from the gas phase, suggesting a direct oxidation pathway for the analyte enriched on the liquid surface via the reactive oxygen atoms formed by the strong electric field.

Graphical abstract: Tuning oxidative modification by a strong electric field using nanoESI of highly conductive solutions near the minimum flow rate

Supplementary files

Article information

Article type
Edge Article
Submitted
30 dek 2022
Accepted
27 mar 2023
First published
11 apr 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 4506-4515

Tuning oxidative modification by a strong electric field using nanoESI of highly conductive solutions near the minimum flow rate

Z. Han, N. Omata, T. Matsuda, S. Hishida, S. Takiguchi, R. Komori, R. Suzuki and L. C. Chen, Chem. Sci., 2023, 14, 4506 DOI: 10.1039/D2SC07113D

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements