title: Determination of pKa values of tenoxicam from 1H NMR chemical shifts and of oxicams from electrophoretic mobilities (CZE) with the aid of programs SQUAD and HYPNMR.
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.
authors.affiliation: Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Area de Química Analítica, México, DF, Mexico.
authors.forename: Damaris
authors.initials: D
authors.lastname: Rodríguez-Barrientos
authors.forename: Alberto
authors.initials: A
authors.lastname: Rojas-Hernández
authors.forename: Atilano
authors.initials: A
authors.lastname: Gutiérrez
authors.forename: Rosario
authors.initials: R
authors.lastname: Moya-Hernández
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Gómez-Balderas
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Ramírez-Silva
mesh_terms: D000465:Algorithms; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D000077239:Meloxicam; D008956:Models, Chemical; D015394:Molecular Structure; D010894:Piroxicam / Q000031:analogs & derivatives* / Q000737:chemistry; D012984:Software; D013237:Stereoisomerism; D013843:Thiazines / Q000737:chemistry; D013844:Thiazoles / Q000737:chemistry
chemical_list: D013843:Thiazines; D013844:Thiazoles; D010894:Piroxicam; C013580:isoxicam; C059451:lornoxicam; D000077239:Meloxicam; C032801:tenoxicam