Hplc grade acetonitrile

Buffer solutions (polar solvents for HPLC experiments) were prepared by dissolving HPLC-grade ammonium acetate (VWR International, Leuven, Belgium) in ultrapure water obtained from a Milli-Q water purification system (Merck Millipore, Darmstadt, Germany). To adjust the buffer solutions’ pH, two concentrated solutions were used: ammonia (Avantor Performance Materials Poland S.A., Gliwice, Poland) and acetic acid (Chempur, Piekary Śląskie, Poland). HPLC-grade acetonitrile (Chempur, Piekary Śląskie, Poland) and isopropanol (VWR International, Leuven, Belgium) were used as non-polar solvents for HPLC experiments.

HPLC grade acetone, ethyl acetate, and meta-phosphoric acid were obtained from Sigma-Aldrich (Poznań, Poland). HPLC grade acetonitrile, HPLC grade methanol, ortho-phosphoric acid, and ultrapure magnesium carbonate were obtained from Chempur (Piekary Śląskie, Poland). Standards of β-carotene, caffeic acid, chlorogenic acid, chlorophyll a, chlorophyll b, dehydroascorbic acid, ferulic acid, gallic acid, kaempferol-3-O-glucoside, lutein, L-ascorbic acid, p-coumaric acid, and quercetin-3-O-rutinoside (HPLC grade, 99.5–99.9% pure) were obtained from Fluka and Sigma-Aldrich (Poznań, Poland). Standards of fructose (99.9% CAS 57-48-7), glucose (99.9% CAS 50-99-7), and sucrose (99.9% CAS 57-50-1) were obtained from Sigma-Aldrich (Warsaw, Poland).