Optima grade acetone

EE2 standard was obtained from Sigma Chemical (St. Louis, Mo, USA); 17α-ethinylestradiol-d4 standard (chemical purity 98%) was purchased from CDN Isotopes (Quebec, Canada). HPLC-grade methanol, methylene chloride, water and ethyl acetate were purchased from Fisher Scientific (Pittsburgh, PA, USA), as were Optima-grade acetone, acetonitrile and hexane, ACS-grade formic acid, and certified n-butyl chloride. Pyridine was obtained from Acros (Fair Lawn, NJ, USA). N,O-bis(trimethylsilyl)fluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TMCS) was purchased from Pierce (Rockford, IL, USA).

100% ethanol obtained from Sigma-Aldrich (St. Louis, MO) was diluted in its vehicle, water, and prepared in a 20:80 ethanol to water volume solution (20%). Administration of alcohol in all tests was done via oral gavage. Alcohol doses with this solution concentration were calculated based on body weight and ranged from 0.5–2 g/kg. Naloxone HCl, purchased from Sigma-Aldrich (St. Louis, MO) was dissolved in 0.9% sodium chloride saline solution. The drug was administered via the subcutaneous route, at a 1 ml/100 g volume-to-body weight ratio. The preparation and route of administration were selected as reported in previous studies (Campbell, Taylor and Tizabi, 2006 (link); Neddenriep et al., 2019 (link)) in both sexes of these two strains of mice.
HPLC chemicals: HPLC grade methanol and de-ionized (DI) water, optima grade acetone, ethanol, methanol, n-propanol and isopropanol were purchased from Fisher Scientific (Hanover Park, Illinois). The ethanol 80 and Volatile Controls were purchased from UTACK^® Laboratories, Inc. (Valencia, CA). Nitrogen and helium gases were acquired from Praxair and Airgas (Richmond, VA).