Structural analyses of sucrose laurate regioisomers by mass spectrometry techniques

6- And 6′-O-lauroyl sucrose were isolated and analyzed by matrix-assisted laser desorption/ionisation (MALDI) time-of-flight (TOF) mass spectrometry (MS), Orbitrap high-resolution (HR) MS, and electrospray-ionization (ESI) tandem mass spectrometry (MS/MS). The analyses aimed to explore the physicochemical differences between the regioisomers and how the position of the fatty acid ester substitution affects the molecular and conformational stability. MALDI-TOF MS resulted in signals characteristic for the molecular ion adducts with sodium and potassium, [M+Na]⁺ and [M+K]⁺, m/z 547.9 and 563.8, respectively, and Orbitrap HRMS confirmed the mass of [M+Na]⁺ (m/z 547.2712). ESI-MS/MS on the precursor ion [M+Na]⁺ resulted in product ion mass spectra showing two high-intensity signals for each sample. 6-O-Lauroyl sucrose produced signals located at m/z 547.27 and m/z 385.21, corresponding to the 6-O-lauroyl glucose sodium adduct ions, while the signals for 6′-O-lauroyl sucrose were located at m/z 385.22 and 367.20, respectively corresponding to the sodium adduct ions with 6-O-lauroyl fructose and 6-O-lauroyl fructosyl. The mass spectra of the two regioisomers were clearly different, and the investigation revealed the importance of the position of the fatty acid ester for the conformational stability and resulting fragmentation pathways of sucrose laurate regioisomers. The results of the employed MS techniques indicated the higher stability of the glycosidic linkage in 6-O-lauroyl sucrose, compared to the 6′-O-regioisomer.