Meprobamate

Meprobamate, carisoprodol, pentobarbital, diazepam, THIP (4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol), salts and buffers were purchased from Sigma Aldrich (St. Louis, MO). GABA was obtained from Acros Organics (New Jersey, US). Bemegride was obtained from Pfaltz & Bauer, Inc. (Waterbury, CT). Stock solutions of Meprobamate, pentobarbital and carisoprodol were made using dimethylsulfoxide (DMSO). Drugs were diluted in normal saline, so that the final DMSO concentration (vol/vol) of the test solutions was ≤0.3%. GABA, diazepam and bemegride stock solutions were prepared using de-ionized H₂O. All stock solutions were stored at −20 °C. On experimental days, drug-containing solutions were prepared from stock by serial dilution into external solution.

A total of 16 PPCP/EDCs with different physicochemical properties were considered in this study (Table 1). Surrogates were used to assess recovery and quantitatively analyze all PPCP/EDCs. Standards of caffeine, carbamazepine, diazepam, diuron, gemfibrozil, meprobamate, perfluorooctanoic acid, and trimethoprim were purchased from Sigma-Aldrich (St. Louis, MO). Standard of primidone was from Spectrum Chemical (Gardena, CA). Standard of sulfamethoxazole was from MP Biomedicals (Solon, OH). Standards of diclofenac and dilantin were from TCI America (Portland, OR). Standards of ibuprofen and naproxen were from Alfa Aesar (Ward Hill, MA). Standards of (3S,5S)-atorvastatin sodium salt, clofibric acid, clofibric-d₄ acid, and perfluorooctane sulfonate were from Santa Cruz Biotechnology (Santa Cruz, CA). Standard of diazepam-d₅ was from Cerilliant (Round Rock, TX). All other deuterated standards were purchased from C/D/N Isotopes (Pointe-Claire, Quebec, Canada). The solvents used in this study were from Fisher (Fair Lawn, NJ) or VWR (Visalia, CA). Ultrapure water was produced using a Barnstead E-Pure water purification system (Thermo Scientific, Dubuque, IA). Individual stock solutions of each compound were prepared in methanol and stored in an amber glass vial at −20 °C.