# Implementation of Infrared-Activated Negative Electron Transfer Dissociation (IR-NETD) Using Xenon on a Quadrupole-Orbitrap-Quadrupole Linear Ion Trap Mass Spectrometer

## TL;DR

This paper introduces a new mass spectrometry technique using infrared lasers and xenon to study RNA molecules, making it easier to analyze complex biopharmaceuticals.

## Contribution

The first implementation of IR-NETD using xenon on a hybrid mass spectrometer with a custom photon detector.

## Key findings

- A home-built photon detector improved laser alignment and xenon integration in the mass spectrometer.
- IR-NETD successfully characterized a complex small interfering RNA molecule with variable laser power and precursor charge states.
- Concurrent IR photoactivation during NETD reactions enhanced the analysis of complex RNA structures.

## Abstract

For tandem mass spectrometry, photoactivation capabilities
enable
a host of useful dissociation strategies. Herein we present the first
implementation of an IR laser system on a next generation, quadrupole-Orbitrap-quadrupole
linear ion trap hybrid MS system (Thermo Scientific Orbitrap Ascend).
In addition, we establish xenon as an efficient source of radical
cations for negative electron transfer dissociation (NETD) reactions.
First, we take advantage of the instrument’s linear architecture
to include a home-built photon detector to improve ease of use and
laser alignment, along with straightforward introduction of xenon
into the instrument. Second, we assess the instrument performance
through infrared-activated NETD (IR-NETD) of a simple, unmodified
6-mer RNA molecule. Finally, we assessed the performance of IR-NETD
for characterizing a synthetically complex small interfering RNA molecule,
evaluating the effects of parameters including precursor charge state
and IR laser power, demonstrating the benefits of concurrent IR photoactivation
during NETD reactions. This straightforward instrumental approach
represents a powerful and versatile tool for the characterization
of complex biopharmaceutical molecules.