Titrisol solutions

Stock solutions at 1 mg mL -1 of BZE in MeOH and cocaine base were provided by Sigma-Aldrich (Saint-Quentin-Fallavier, France). The working solutions at 1 µg mL -1 were obtained by dilution of the stock solution (1 mg mL -1 ) in HPLC-grade ACN (Carlo Erba, Val-de-Reuil, France). These solutions were stored at -20°C. MeOH, EtOH, and isooctane were purchased from Carlo Erba. Acetic acid and anhydrous ACN were provided by Sigma-Aldrich. 1 M NaOH and 0.1 M HCl were obtained using deionized water (Milli-Q purification system, Millipore, Molsheim, France) and Titrisol solutions from Merck (Darmstadt, Germany). MAA, TRIM, and 3-(trimethoxysilyl)propyl methacrylate (γ-MAPS) were purchased from Sigma-Aldrich. Azo-N,N'-diisobutyronitrile (AIBN) was purchased from Acros Organics (Noisy-le-Grand, France). MAA was distilled under vacuum in order to remove inhibitors and stored at -20°C. TRIM, AIBN, and γ-MAPS were of satisfactory purity so they were used without further purification. Fused-silica capillaries with a UV transparent fluorocarbon polymer coating (PTFE-coated silica capillaries, 100 µm i.d. x 375 µm outer diameter (o.d.)) were purchased from Polymicro Technologies (Photon Lines, Saint Germain-en-Laye, France).