Sodium doping and trapped ion mobility spectrometry improve lipid detection for novel MALDI-MSI analysis of oats

Wai C D Lau; Leigh Donnellan; Matthew Briggs; Thusitha Rupasinghe; John C Harris; Julie E Hayes; Peter Hoffmann

doi:10.1016/j.foodchem.2023.137275

Sodium doping and trapped ion mobility spectrometry improve lipid detection for novel MALDI-MSI analysis of oats

Food Chem. 2024 Feb 1:433:137275. doi: 10.1016/j.foodchem.2023.137275. Epub 2023 Aug 26.

Authors

Wai C D Lau¹, Leigh Donnellan¹, Matthew Briggs¹, Thusitha Rupasinghe², John C Harris³, Julie E Hayes⁴, Peter Hoffmann⁵

Affiliations

¹ UniSA Clinical and Health Sciences, Health and Biomedical Innovation, University of South Australia, Adelaide, South Australia 5000, Australia.
² SCIEX, Australia.
³ South Australian Research and Development Institute, Department of Primary Industries and Regions, Adelaide, South Australia 5000, Australia; School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia 5064, Australia.
⁴ School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, South Australia 5064, Australia.
⁵ UniSA Clinical and Health Sciences, Health and Biomedical Innovation, University of South Australia, Adelaide, South Australia 5000, Australia. Electronic address: peter.hoffmann@unisa.edu.au.

PMID: 37660601
DOI: 10.1016/j.foodchem.2023.137275

Abstract

Oat (Avena sativa L.) is an important cereal grain with a unique nutritional profile including a high proportion of lipids. Understanding lipid composition and distribution in oats is valuable for plant, food and nutritional research, and can be achieved using MALDI mass spectrometry imaging (MALDI-MSI). However, this approach presents several challenges for sample preparation (hardness of grains) and analysis (isobaric and isomeric properties of lipids). Here, oat sections were successfully mounted onto gelatin-coated indium tin oxide slides with minimal tearing. Poor detection of triacylglycerols was resolved by applying sodium chloride during mounting, increasing signal intensity. In combination with trapped ion mobility spectrometry (TIMS), lipid identification significantly improved, and we report the separation of several isobaric and isomeric lipids with visualisation of their "true" spatial distributions. This study describes a novel MALDI-TIMS-MSI analytical technique for oat lipids, which may be used to improve the discovery of biomarkers for grain quality.

Keywords: Isobaric and isomeric; Lipids; MALDI-MSI; Oat; Sodium doping; TIMS.