Anhydrous dipotassium hydrogen phosphate

Folin–Ciocalteu's reagent, acetone, ethanol, sodium dihydrogen phosphate monohydrate, anhydrous dipotassium hydrogen phosphate, anhydrous sodium carbonate, sodium acetate, potassium chloride, butylated hydroxyl toluene (BHT), and methanol were purchased from Merck (Darmstadt, Germany). 2, 2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical and ferric reducing antioxidant power assay (FRAP) reagent were purchased from Sigma‐Aldrich (Steinheim, Germany). Gallic acid and fluorescein sodium were provided by Fluka (Madrid, Spain).

Oxycodone hydrochloride (OxyNorm®, Mundipharma), isoflurane (Isoflo® vet., 100%, solution, Zoetis, Finland), heparin (5000 IU/mL, Heparin LEO), buprenorphine (Temgesic®, 0.3 mg/mL solution for injection, Indivior Eur. Ltd), lidocaine (Xylocain®, 100 mg/mL, cutaneous spray, Aspen Nordic, Denmark) and sterile saline (B. Braun Medical AB, Danderyd, Sweden) were purchased from Distansapoteket Stockholm (Apoteket AB, Stockholm, Sweden). Oxycodone hydrochloride (Eur. Qual D, APL, Kungens Kurva, Sweden) was purchased from Distansapoteket (Falun, Sweden). Oxycodone-D3 and oxycodone-D6 (Cerriliant), sodium chloride, potassium chloride, magnesium chloride, calcium dichloride, ascorbic acid, and potassium dihydrogen phosphate were purchased from Sigma-Aldrich (Saint Louis, USA). Anhydrous dipotassium hydrogen phosphate, formic acid (98–100%) and acetonitrile (gradient grade for liquid chromatography) were purchased from Merck (Darmstadt, Germany). The Milli-Q Academic system (Millipore, Bedford, MA, USA; Resistance 18.2 Ohm; Millipak®Express 20 Filter, 0.22 μm) was purchased from Merck Millipore (Burlington, MA, USA). Dental cement (Dentalon Plus; Heraeus Kulzer GmbH) was purchased from AgnTho’s AB (Lidingö, Sweden). Heparinized saline solution (100 IU heparin/mL) was prepared in house.