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

• Published in: Food chemistry Vol. 433; p. 137275
• Main Authors: Lau, Wai C.D., Donnellan, Leigh, Briggs, Matthew, Rupasinghe, Thusitha, Harris, John C., Hayes, Julie E., Hoffmann, Peter
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2024
• Subjects: Avena sativa; biomarkers; food chemistry; grain quality; hardness; indium tin oxide; Isobaric and isomeric; lipid composition; Lipids; MALDI-MSI; matrix-assisted laser desorption-ionization mass spectrometry; nutrient content; Oat; oats; sodium; sodium chloride; Sodium doping; TIMS; triacylglycerols; Lipids; Oat; Isobaric and isomeric; MALDI-MSI; TIMS; Sodium doping
• ISSN: 0308-8146; 1873-7072; 1873-7072
• DOI: 10.1016/j.foodchem.2023.137275

•Novel MALDI-MSI performed to visualise spatial distribution of oat lipids.•Detection of oat triacylglycerols enhanced via sodium doping.•TIMS activation improved signal intensities and lipid identification.•Isobaric lipids with distinct localisation patterns were identified in oats.•Findings may support further explorations into physiological roles of lipids in oats. 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.