Determination of pKa values of tenoxicam from H NMR chemical shifts and of oxicams from electrophoretic mobilities (CZE) with the aid of programs SQUAD and HYPNMR |
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| Authors: | Damaris Rodrí guez-Barrientos,Atilano Gutié rrez,Rodolfo Gó mez-Balderas |
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| Affiliation: | a Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Área de Química Analítica, Apartado Postal: 55-534, 09340 México, D. F., Mexico
b Universidad Nacional Autónoma de México, Facultad de Estudios Superiores-Cuautitlán, Unidad de Investigación Multidisciplinaria, Laboratorio de Fisicoquímica Analítica, 54714 Cuautitlán Izcalli, Edo. de México, Mexico |
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| 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 pKa values of tenoxicam in H2O/DMSO 1:4 (v/v) have been obtained from 1H NMR chemical shifts, as well as of oxicams in aqueous solution from electrophoretic mobilities determined by CZE, at 25 °C. These values are in very good agreement with those reported by spectrophotometric and potentiometric measurements. |
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| Keywords: | Oxicams SQUAD HYPERQUAD HYPNMR pKa values 1H NMR chemical shifts CZE Electrophoretic mobility |
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