Chromatographic grade methanol meoh

Chromatographic grade methanol (MeOH) was supplied by Merck (Darmstadt, Germany). Ethanol, ethyl acetate (EtOAc), and hydrochloric acid (HCl) were purchased from Beijing Chemistry Factory (Beijing, China). Doxorubicin hydrochloride was purchased from Beijing Huafeng United Technology Co. (Beijing, China). Standards of cyanidin-3-O-glucoside chloride [molecular weight (MW) 484.84, purity ≥ 98%] and cyanidin chloride (MW 322.7, purity ≥ 97%) were purchased from Sigma-Aldrich Chemical Co. (St Louis, MO, USA).

Chromatographic grade methanol (MeOH) used for HPLC was purchased from Merck (Darmstadt, Germany). 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), acetic acid (CH₃COOH), were purchased from Sigma-Aldrich (St Louis, MO, USA). Isotopically labeled internal standard (IS), [¹⁵N₅]8-oxo-7,8-dihydro-2′-deoxyguanosine ([¹⁵N₅]8-oxodG) was purchased from Cambridge Isotope Laboratories Inc. (Andover, MA, USA). Water used throughout all experiments was purified using a Milli-Q water purification apparatus (Millipore, Milford, MA, USA). 8-oxodG and [¹⁵N₅]8-oxodG were dissolved in water to a stock concentration of 1 mM and 0.1 mM, respectively. Aliquots were stored at −80°C until use. When required, these were diluted to 1 μM in water.