Effective Identification and Highly Sensitive Quantification\nof Fructo-oligosaccharide Isomers with Bi<sub>2</sub>Se<sub>3</sub> Nanosheet-Assisted Laser Desorption Ionization Mass Spectrometry

The\ngrowing interest in fructo-oligosaccharides (FOSs) necessitates\nthe effective monitoring of product quality. Identifying and quantifying\nFOS isomers from the same sources are challenging. Here, we report\na new method using Bi<sub>2</sub>Se<sub>3</sub> nanosheets as the\nmatrix for matrix-assisted laser desorption ionization mass spectrometry\n(MALDI-MS), achieving effective differentiation of oligosaccharide\nisomers through MALDI-MS/MS. Notably, four isomers of pentasaccharides\nand two isomers of heptasaccharides were successfully identified,\nwith a remarkably low limit of detection of 0.06 pmol. Our approach\nenabled the specific quantification of 1F-fructofuranosylnystose in\ncommercial FOS products, positioning it as a promising tool for oligosaccharide\nisomer quantification in nutritional food products. Furthermore, this\ntechnique facilitates the rapid and sensitive detection of various\nsaccharides and a wide range of other small molecules with enhanced\nsignal intensities and improved reproducibility. Overall, it facilitates\nthe rapid, selective, and sensitive detection of various saccharides\nand other small molecules, enhancing analytical chemistry and food\nscience applications.