13c15n2 8 oxogua

The analytical reference standards of 8-oxoGua, 8-oxoGuo, and 8-oxodGuo were purchased from Spectra 2000 s.r.l (Rome, Italy). The isotope-labeled internal standard (13C15N2) 8-oxoGua (98%) was obtained from Cambridge Isotope Laboratories Inc. (Tewksbury, MA, USA), (13C15N2) 8-oxoGuo (13C15N2) and 8-oxodGuo were obtained from CDN Isotopes Inc. (Pointe-Claire, QC, Canada). 3-NO₂Tyr was purchased from Cayman Chemical Company (Ann Arbor, MI, USA) and 3NO₂Tyr d3 from TRC (Toronto, ON, Canada). Glacial acetic acid 30% NH₃, dimethyl sulfoxide, sodium hydroxide solution (50–52% in water), CHROMASOLV^® gradient grade 99.9% methanol and acetonitrile for HPLC/MS 99.9%, and low benzene content carbon disulfide were obtained from Sigma Aldrich (Saint Louis, MO, USA). Purified water was obtained from a Milli-Q Plus system (Millipore Milford, MA, USA). Anotop 10LC syringe filter devices (0.2 m pore size, 10 mm diameter) were purchased from Whatman Inc. (Maidstone, UK). Luna 5 µ C8 100 Å (250 × 4.6 mm) (Phenomenex, Torrance, CA, USA) and Discovery C18 (150 × 4.6 mm, 5 µm) (Supelco Analytical, Bellefonte, PA, USA) were used throughout the study.

The analytical reference standards of 8-oxoGua, 8-oxodGuo, and 8-oxoGuo were purchased from Spectra 2000 SRL (Rome, Italy). The isotope-labelled internal standards (13C15N2), 8-oxodGuo, and (13C15N2) 8-oxoGuo were obtained from C/D/N Isotopes Inc. (Pointe-Claire, QC, Canada). The (13C15N2) 8-oxoGua (98%) was obtained from Cambridge Isotope Laboratories Inc. (Tewksbury, MA, USA). The 3-NO2Tyr was purchased from Cayman Chemical Company (Ann Arbor, MI, USA) and 3-NO2Tyr d3 from Toronto Research Chemicals (Toronto, ON, Canada). The 5-MeCyt was obtained from Sigma Aldrich SRL (Milano, Italy) and Cotinine d3 from CDN Isotopes Inc. (Pointe-Claire, QC, Canada). Glacial acetic acid 30% NH3, dimethyl sulfoxide, sodium hydroxide solution (50–52% in water) and CHROMASOLV^® gradient grade 99.9% methanol and acetonitrile for HPLC/MS 99.9% carbon disulfide low benzene content were obtained from Sigma Aldrich (Saint Louis, MO, USA). Purified water was obtained from a Milli-Q Plus system (Millipore, Milford, MA, USA). Anotop 10LC syringe filter devices (0.2 m pore size, 10 mm diameter) were purchased from Whatman Inc. (Maidstone, UK). The Kinetex Polar C18 column 100 A (150 × 4.6 mm, 2.6 m), supplied by Phenomenex (Torrance, CA, USA), was used throughout the study.