Effective Identification and Highly Sensitive Quantification of Fructo-oligosaccharide Isomers with Bi₂Se₃ Nanosheet-Assisted Laser Desorption Ionization Mass Spectrometry

The growing interest in fructo-oligosaccharides (FOSs) necessitates the effective monitoring of product quality. Identifying and quantifying FOS isomers from the same sources are challenging. Here, we report a new method using Bi₂Se₃ nanosheets as the matrix for matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), achieving effective differentiation of oligosaccharide isomers through MALDI-MS/MS. Notably, four isomers of pentasaccharides and two isomers of heptasaccharides were successfully identified, with a remarkably low limit of detection of 0.06 pmol. Our approach enabled the specific quantification of 1F-fructofuranosylnystose in commercial FOS products, positioning it as a promising tool for oligosaccharide isomer quantification in nutritional food products. Furthermore, this technique facilitates the rapid and sensitive detection of various saccharides and a wide range of other small molecules with enhanced signal intensities and improved reproducibility. Overall, it facilitates the rapid, selective, and sensitive detection of various saccharides and other small molecules, enhancing analytical chemistry and food science applications.