Rapid lipid a structure determination via surface acoustic wave nebulization and hierarchical tandem mass spectrometry algorithm

Rapid Commun Mass Spectrom. 2016 Dec 15;30(23):2555-2560. doi: 10.1002/rcm.7728.

Abstract

Rationale: Surface acoustic wave nebulization (SAWN) is an easy to use sample transfer method for rapid mass spectrometric analysis. A new standing wave (SW) SAWN chip, with higher ionization efficiency than our previously reported design, is used for rapid analysis of lipids.

Methods: The crude, yet fast, Caroff protocol was used for lipid A extraction from Francisella novicida. SW-SAWN with a Waters Synapt G2S quadrupole time-of-flight (QTOF) mass spectrometer was used to generate lipid A ions. Quadrupole collision-induced dissociation (Q-CID) of lipid A at varying CID energies was used to approximate the ion trap MSn data required for our hierarchical tandem mass spectrometry (HiTMS) algorithm. Structural hypotheses can be obtained directly from the HiTMS algorithm to identify species-specific lipid A molecules.

Results: SW-SAWN successfully generated ions from lipid A extracted from Francisella novicida using the faster Caroff method. In addition, varying collision energies were used to generate tandem mass spectra similar to MS3 and MS4 spectra from an ion trap. The Q-CID spectra are compatible with our HiTMS algorithm and offer an improvement over lipid A tandem mass spectra acquired in an ion trap.

Conclusions: Combining SW-SAWN and Q-CID enabled more structural assignments than previously reported in half the time. The ease of generating spectra by SAWN tandem MS in combination with HiTMS interpretation offers high-throughput lipid A structural analysis and thereby rapid detection of pathogens based on lipid fingerprinting. Copyright © 2016 John Wiley & Sons, Ltd.