CIDEPINT   05376
CENTRO DE INVESTIGACIONES EN TECNOLOGIA DE PINTURAS
Unidad Ejecutora - UE
artículos
Título:
conversion parameter between pH scales ( and ) in acetonitrile/water mixtures at various compositions and temperatures
Autor/es:
GAGLIARDI, L. G; CASTELLS, C. B.; RÀFOLS, C.; ROSÉS, M.; BOSCH, E.
Revista:
ANALYTICAL CHEMISTRY
Editorial:
American Chemical Society
Referencias:
Lugar: North Carolina; Año: 2006
ISSN:
0003-2700
Resumen:
The (s,s)pH in acetonitrile/water mixtures at different temperatures cannot be directly measured because of the lack of calibration buffers in these hydroorganic media at most temperatures different from 25ºC. In this paper the d-parameter has been determined for acetonitrile/water mixtures from 0 up to 90% of acetonitrile at different temperatures from 15 to 60ºC and the values fitted to a very simple simultaneous function of composition and temperature. The d values allow conversion of the (s,w)pH scale (pH measured in acetonitrile/water with electrodes calibrated in water) to the scale (pH measured in acetonitrile/water with electrodes calibrated in the same acetonitrile/water mixture). The practical determination of (s,w)pH is direct because the calibration of the electrodes is carried out with commercial aqueous standard buffers. Thus, the pH value of any buffered acetonitrile/water mobile phase used in reversed-phase liquid chromatography, which is directly related to the ionized fraction of analyte and, therefore, to its average retention, can be easily known at any temperature from the measured (s,w)pH and the corresponding d value.