Chlorogenic acid 3 caffeoylquinic acid

HPLC-grade standard substances, namely neochlorogenic acid (5-caffeoylquinic acid), chlorogenic acid (3-caffeoylquinic acid), cryptochlorogenic acid (4-dicaffeoylquinic acid), 4,5-dicaffeoylquinic acid, 1,5-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 3,4-dicaffeoylquinic acid were purchased from Sigma–Aldrich GmbH (Steinheim, Germany). Solvents and other substances were obtained as follows: acetonitrile (purity 99.9%) and methanol (purity 99.9%) from Sigma-Aldrich (Steinheim, Germany); trifluoroacetic acid (purity 99.8%) supplied from Merck (Darmstadt, Germany); 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) di-ammonium salt (ABTS) (purity ≥ 98%) and potassium persulphate (purity ≥ 99%) purchased from Sigma (St. Louis, MO, USA); Trolox (purity ≥ 98%) received from Fluka Chemika (Buchs, Switzerland). Ultrapure water was purified using a Millipore water-cleaning system (Bedford, MA, USA).

The following standards were used for the identification and quantification of phenolic compounds: p-coumaric acid, caffeic acid, gallic acid, sinapic acid, chlorogenic acid (3-caffeoylquinic acid), cryptochlorogenic acid (4-caffeoylquinic acid), sinapic acid (Sigma-Aldrich Chemie GmbH, Buchs, Switzerland), quercetin-3-O-glucoside, and kaempferol-3-O-glucoside (Fluka Chemie GmbH, Buchs, Switzerland).
A Milli-Q water purification system from Millipore (Bedford, MA, USA) was used for the bi-distillation and purification of the water used. The acetonitrile and formic acid used as mobile phases for MS analysis were of HPLC-MS quality (Fluka Chemie GmbH). The methanol used for the extraction of the phenolic compounds was of the quality HPLC-MS (Sigma-Aldrich Chemie GmbH).