D arabinose

Hawthorn of the variety “Big Venus” was purchased in local supermarket (Baoding, China) at a fully mature ready-to-eat stage. Polyphenols including epicatechin (≥96%) and chlorogenic acid (98%), monosaccharides standards (D-galacturonic acid (98%), D-glucose (98%), D-mannose (98%), D-rhamnose (98%), D-galactose (98%), D-fucose (98%), D-arabinose (98%)), cellulase (400 U/mg), D3520 macroporous resin, phenol and 3-phenylphenol were obtained from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). All other chemicals and reagents were of analytical grade and obtained from Baoding Qianyue Trading Co., Ltd. (Baoding, China).

An Ultimate 3000 UPLC system (Thermo Fisher Scientific, USA) coupled with an electrospray ionization triple-quadrupole mass spectrometer (TSQ Endura, Thermo Fisher Scientific, USA) was used in this study. Chromatographic separation was carried out with an XAmide column (150 mm × 2.1 mm i.d., 5 μm) using an UltiMate 3000 HPLC system (Dionex, Sunnyvale, CA, USA). The column was kept at 40°C with a mobile phase of 0.1% formic acid (A) and acetonitrile (B) at a flow rate of 0.2 mL/min. Gradient elution began with 80% B and was then programmed as follows: 75% B from 0 min to 5 min, 60% B from 5 min to 10 min, and 85% B from 10 min to 20 min. MS detection was performed using a triple quadrupole mass spectrometer equipped with an electrospray ion source in positive and negative ionization modes.
The optimized mass spectrometric conditions were as follows: positive mode voltage, 3.5 kV; negative mode voltage, 2.5 kV; sheath gas flow, 35 arb; aux gas flow, 10 arb; ion transfer tube temperature, 325°C; vaporizer temperature, 275°C; and mass scan range, m/z 50–1000.
The sample spectra were compared with those of standards. Standards of maltotriose, α-D-lactose monohydrate, maltose, D-galactose, sucrose, D-(+)-xylose, D-glcNAc, rhamnose, D-fructose, D-(-)-arabinose, D-mannose, and D-(+)-glucose were purchased from YuanYe Biotechnology Company (Shanghai, China).