UPLC-QTOF-MS/MS Analysis of Polysaccharides

The conditions of UPLC-QTOF-MS/MS are in accordance with the previous study [12 (link), 13 (link)]. Briefly, the analysis was performed on a Waters Acquity UPLC I-Class system (Waters Corp., Milford, United States), coupled with a Waters QTOF-MS/MS Mass System (Manchester, United Kingdom) equipped with electrospray ionization (ESI). Chromatographic separation was performed on a Waters Acquity UPLC HSS T3 column (100 mm × 2.1 mm, 1.8 μm). Mass range, 50-1500 Da; source temperature 100 °C; desolvation temperature, 450 °C; desolvation gas flow, 900 L/h; sampling cone, 40 V; ESI⁻ capillary voltage, 2.5 KV; and ESI⁺ capillary voltage, 0.5 KV. UPLC-QTOF-MS/MS system was controlled by the Masslynx 4.1 platform. The MS^E data collected in a continuum mode were processed using the peak detection and alignment algorithms in UNIFI 1.8, which enabled quasi-molecular ion peaks, adduct ions, and fragment ions to be analyzed as a single entity. RSGB (sugar-free) was filtered through a 0.22 μm microporous membrane before aliquots (2 µL) were transferred to autosampler vials for analysis. Fifteen standards were dissolved in methanol, respectively, and mixed in equal. The final concentration of each standard was 100 ng/mL, and 1µL for analysis.