Epitestosterone

Reference standards of the 32 eicosanoids used in this study (Table 1) were obtained from Cayman Chemical (Ann Arbor, MI, USA). The following internal standards were also purchased from Cayman Chemical: 3,3,4,4-d₄-6-keto PGF_1α for 6-keto PGF_1α, 3,3,4,4-d₄-PGE₂ for the seven prostaglandins and for 11-dehydro TXB₂, 3,3,4,4-d₄-8-iso PGF_2α for the ten isoprostanes, 6,7,14,15-d₄-LTB₄ for the four leukotrienes, 5,6,8,9,11, 12,14,15-d₈-12(S)-HETE for TXB₂ and for the five hydroxyeicosaeonic acids, and 5,6,8,9,11,12,14,15-d₈-AA for AA. Epitestosterone was obtained from Steraloids (Newport, RI, USA). For solid-phase extraction (SPE), an Oasis MAX cartridge (1 mL, 30 mg; Waters; Milford, MA, USA) was preconditioned with 1 mL methanol followed by 1 mL deionized water. L-Ascorbic acid (reagent-grade) and formic acid (mass spectrometry-grade, 98% purity) were obtained from Sigma (St. Louis, MO, USA), while HPLC-grade methanol and acetonitrile were acquired from Burdick & Jackson (Muskegon, MI, USA). Deionized water was prepared using a Milli-Q purification system (Millipore; Billerica, MA, USA). Ultrafree-MC polyvinylidene fluoride membrane (0.1-µm pore size) filters were obtained from Millipore.