Ethyl 2 furoate

The deuterated internal standards of caffeic acid-d₆ (CAS 2708298-33-1, ≥99%) and furfural-d₄ (CAS 1219803-80-1, ≥98%) were purchased from CDN Isotopes (Pointe-Claire, QC, Canada). furfural ethyl ether (CAS 6270-56-0, ≥97%) was purchased from Fisher Scientific (Hampton, NH, USA). The following compounds were purchased from Sigma-Aldrich Inc. (Oakville, ON, Canada); caffeic acid (CAS 331-39-5, ≥98%), caftaric acid (CAS 67879-58-7, ≥97%), 3-acetyl-2,5-dimethylfuran (CAS 10599-70-9, ≥98%), 2-furanmethanethiol (CAS 98-02-2, ≥98%), 2,3-dihydrobenzofuran (CAS 496-16-2, ≥99%), 2-acetylfuran (CAS 1192-62-7, ≥99%), 5-methylfurfural (CAS 620-02-0, ≥98%), homofuraneol (CAS 27538-09-06, ≥96%), furfural (CAS 98-01-1, ≥99%), sodium chloride (NaCl, ≥99%) and ethyl-2-furoate (CAS 614-99-3, ≥99%). All solvents used were HPLC grade purity. Potassium metabisulphite (KMS) and potassium bitartrate (cream of tartar) were purchased from Scott Laboratories Ltd. (Niagara-on-the-Lake, ON, Canada). D-fructose (≥99%) was purchased from BioShop^® Canada Inc. (Burlington, ON, Canada). Milli-Q water was obtained Millipore (Saint-Quentin-en-Yvelines, France).

Ethyl acetate, ethyl 2-methylpropionate, propyl acetate, ethyl propionate, ethyl butyrate, isobutyl acetate, ethyl 2-methylbutyrate, ethyl 3-methyl butyrate, isoamyl acetate, ethyl valerate, butyl butyrate, ethyl hexanoate, isoamyl butyrate, propyl hexanoate, ethyl heptanoate, ethyl lactate, 3-methylbutyl hexanoate, propyl octanoate, ethyl nonanoate, hexyl hexanoate, ethyl 2-furoate, ethyl caprate, ethyl benzoate, ethyl phenylacetate, ethyl laurate, ethyl 3-phenylpropanoate, ethyl tetradecanoate, ethyl pentadecanoate, ethyl palmitate, ethyl oleate, and linoleic acid ethyl ester were obtained from Sigma-Aldrich (Shanghai, China). The internal standard (IS) was 2-octanol (Sigma-Aldrich, Shanghai, China). The linear retention index (RI) was determined with a C7–C30 n-alkane mixture (Sigma-Aldrich, Shanghai, China). All of the reagents used were of analytical grade with a purity of at least 97%, and most with a purity exceeding 99%. A Milli-Q purification system provided pure water (Millipore, Bedford, MA, USA). Sodium chloride (analytical grade) and absolute ethanol (analytical grade) were obtained from Sino-pharm Chemical Reagent Co., Ltd (Shanghai, China).