[Study of local anesthetics. CLVII. Chromatographic properties of pentacaine, carbisocaine, heptacaine and its 3-, and 4-positional isomers in the RP HPLC system].

The present study aimed to find a suitable HPLC system for the determination of the values of the capacity factor of k' pentacaine, carbisocaine, heptacaine, and its 3-, and 4-positional isomers. The column Separon SG X C-18 and a mobile phase consisting of 90% methanol and 10% water (with 0.5 mol/l of sodium acetate) were demonstrated to be suitable for the separation of these potential local anaesthetics from the group of phenylcarbamic acid derivatives. In this system, k'o for pentacaine is 22.9, for carbisocaine 8.6, for heptacaine 8.1, and for 3-positional derivative of heptacaine, 13.0, and 4-isomer, 18.4. It results from the data that log k' of these drugs is in the interval 2-5 and even minor changes in the concentration of sodium acetate (c = 0.5 +/- 0.05 mol/l) do not change it markedly.