Determination of pKavalues of tenoxicam from1H NMR chemical shifts and of oxicams from electrophoretic mobilities (CZE) with the aid of programs SQUAD and HYPNMR

Damaris Rodríguez-Barrientos, Alberto Rojas-Hernández, Atilano Gutiérrez, Rosario Moya-Hernández, Rodolfo Gómez-Balderas, María Teresa Ramírez-Silva, Damaris Rodríguez-Barrientos, Alberto Rojas-Hernández, Atilano Gutiérrez, Rosario Moya-Hernández, Rodolfo Gómez-Balderas, María Teresa Ramírez-Silva

Index: Talanta 80(2) , 754-62, (2009)

Full Text: HTML

Abstract

In this work it is explained, by the first time, the application of programs SQUAD and HYPNMR to refine equilibrium constant values through the fit of electrophoretic mobilities determined by capillary zone electrophoresis experiments, due to the mathematical isomorphism of UV-vis absorptivity coefficients, NMR chemical shifts and electrophoretic mobilities as a function of pH. Then, the pK(a) values of tenoxicam in H(2)O/DMSO 1:4 (v/v) have been obtained from (1)H NMR chemical shifts, as well as of oxicams in aqueous solution from electrophoretic mobilities determined by CZE, at 25 degrees C. These values are in very good agreement with those reported by spectrophotometric and potentiometric measurements.