Testosterone d3

Testosterone, epiTestosterone, androsterone, etiocholanolone, 5α-androstane-3α,17β-diol, 5βandrostane-3α,17β-diol, dehydroepiandrosterone, 5β-androstanedione, 4-androstenedione and Testosterone-d3 were purchased from Steraloids Inc. (Newport, RI, USA); 5α-dihydroTestosterone was provided by LGC Promochem SRL (Milan, Italy). Isopropyl alcohol, methanol, methyl tertbutyl ether (TBME), ethyl acetate, 17α-methylTestosterone, dithioerythritol and N-Methyl-N-

Chemical reagents, including methanol and acetonitrile (ACN), were purchased from Sigma-Aldrich (Milan, Italy). Clostebol and testosterone-d3 were purchased from Steraloids (USA).
Clostebol acetate was purchased from Sigma-Aldrich (Milan, Italy). Ultrapure water was obtained by a Milli-Q Millipore system (Bedford, MA, U.S.A.). A Precellys 24 Tubes Homogenizer (Bertin Pharma, Montigny-Le-Bretonneux, France) equipped with six 2.8 mm metal beads was used for hair milling. Stock standard solutions of analytes and internal standard (IS), were prepared in methanol at a concentration of 1 mg/mL and stored at -20°C in dark vials. Working methanolic solutions containing all the analytes at different concentrations were prepared by mixing the stock solutions at the proper dilution. The working solutions were used to spike negative hair samples at various levels.