CIDEPINT   05376
CENTRO DE INVESTIGACIONES EN TECNOLOGIA DE PINTURAS
Unidad Ejecutora - UE
artículos
Título:
Simultaneous effect of pH, temperature and mobile phase composition in the chromatographic retention of ionizable compounds
Autor/es:
P. AGRAFIOTOU; C. RAFOLS; C. B. CASTELLS; E. BOSCH; M. ROSES
Revista:
JOURNAL OF CHROMATOGRAPHY - A
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2011 vol. 1218 p. 4995 - 5009
ISSN:
0021-9673
Resumen:
The  retention of 22 monoprotic acid-base solutes in 12 buffers (pH from 2 to 12) at 3 temperatures (25, 40 and 55ºC) and in 3 mobile phase compositions (20, 40 and 60% acetonitrile) was measured. The retention data for each solute, temperature and mobile phase  compositions was fitted to pH by means of the common sigmoidal equation and the retention  and acid-base parameters were obtained (log kHA, log kA and pKa). The dependence of these  parameters on temperature (van?t Hoff plots), mobile phase composition (, volume fraction  of acetonitrile) and mobile phase polarity (Nm P  parameter) was investigated. Linear plots of  the parameter values against the reverse of the absolute temperature, on one hand, and  or  Nm P, in the other hand, were generally obtained. From this analysis we propose 6-parameter equations to relate retention to pH and T at constant mobile phase composition, and to pH and    or Nm P   at constant temperature. A general 12 parameter equation is also proposed to relate retention simultaneously to pH, T and  or Nm P.  The general constancy of some terms of the  equations  allow to simplify the  12 parameter  equation  to  a  8 parameter equation able to  predict retention of the  studied  solutes.  The   accuracy of the proposed method provided excellent results with the advantage of modeling  the effects of various  optimization variables (modifier  concentration, mobile phase pH and  temperature) using a single equation, based on only eight fitting parameters.