D gluconic acid lactone

Alginic acid, D-(+)-glucose, sodium chloride, ethylenediaminetetraacetic acid (EDTA), and deuterium oxide (heavy water) were purchased from Sigma-Aldrich (St Louis, MI, USA); calcium carbonate was from Acros organics (Fisher Scientific, Waltham, MA, USA), and D-(+)-Gluconic acid-lactone was from Sigma Life Science (St Louis, MI,, USA). Deuterated D-glucose (1,2,3,4,5,6,6-D7, 97–98%) was purchased from Cambridge Isotope Laboratories Inc (Tewksbury, MA, USA). All chemicals had a purity of 98–99%.
Prior to use, alginate 0.5 wt % was dialyzed (Spectra/Por 7 membrane, Mw with a cut-off size of 15 kDa, Spectrum Labs, San Francisco, CA, USA) against deionized water (2 days) and against 0.01 M EDTA (2 days). After dialysis, alginate was freeze dried and stored at 4 °C for further experiments.

Tartaric acid, glucose, methanol, methylene chloride, NaCl, and NaOH were of analytical grade and purchased from Beijing Chemical Works (Beijing, China). D-Gluconic acid lactone, polyvinylpolypyrrolidone (PVPP), and all monoterpene standards were purchased from Sigma-Aldrich (St. Louis, MO, USA). Glycosidase AR2000 was received from DSM Food Specialties Beverage Ingredients (Heerlen, Netherlands). Cleanert PEP-SPE (50 mg/6 mL) and Cleanert ODS-C18 (150 mg/6 mL) were purchased from Bonna-Agela Technologies (Tianjin, China).