Mepivacaine

All solutions were prepared using reagent grade chemicals and double distilled water. Mepivacaine standard solution (2830.0 μg mL -1 , 1.0 × 10 -2 mol L -1 ) was prepared daily by dissolving 0.2830 g of Mepivacaine hydrochloride (Sigma-Aldrich, Germany) in water in a 100.0-mL volumetric flask. Operational solutions were prepared by appropriate dilution of the stock solution when used. Standard solution of Ru(phen) 3 2+ (0.01 mol L -1 ) was prepared by dissolving 0.3640 g of dichlorotris(1,10-phenanthroline)ruthenium(II) hydrate (Sigma-Aldrich, Germany) in water in a 50.0 mL volumetric flask. In order to prepare each one of Ce(IV) solutions with concentrations between 1.0 × 10 -3 and 2.0 × 10 -2 mol L -1 , the calculated amount of ceric ammonium nitrate (Riedel-de Haën, Germany) was dissolved in appropriate volume of H 2 SO 4 solution (1.0 mol L -1 ) and then, the solution was further diluted with distilled water in a 100.0-mL volumetric flask. Final concentration of H 2 SO 4 in the Ce(IV) solutions was between 0.03 and 0.20 mol L -1 . Methanol was purchased from Caledon, Canada. The plasma was obtained from patients not exposed to any drug for at least 72 h (blank plasma) and was kindly supplied by health centre of Gorgan, Iran. Mepivacaine injections were purchased from local drugstores.