ABSTRACT
A simple and robust method for the separation and quantification of epinephrine in dental anesthetic solutions was developed. The method allows the direct injection of high salt solutions without sample pre-treatment. Large sample plugs (5.7% of the total capillary length) are used for epinephrine determination by selective analyte focusing in capillary electrophoresis. The concentration detection limit for epinephrine is about 5.0 x 10(-7) M (90 ng ml-1) with a commercial UV detector. The separation protocol was validated in terms of its precision, linearity, accuracy and specificity.
Subject(s)
Anesthesia, Dental , Anesthetics, Local/chemistry , Epinephrine/analysis , Vasoconstrictor Agents/analysis , HumansABSTRACT
A series of homologous amphiphilic molecules with surface areas in the range of 0.3 nm2 to 3.0 nm2 were prepared and used to investigate the diffusion in model dimyristoylphosphatidylcholine membranes as a function of temperature. The diffusion behavior of smaller molecules can be described by the interfacial viscosity limited free area theory promoted by Vaz and his co-workers, and that of the larger molecules can best be modeled by a recent interpretation of the theoretical description proposed by Evans and Sackmann. The experimental data show that the rate of diffusion is controlled by the size of the molecules at the interface of the lipid membrane, and provide evidence for a view of the membrane as a hydrodynamic triple layer with a low-viscosity central layer encased by two more viscous, yet fluid, layers.
