Retention of ionisable compounds on high-performance liquid chromatography XIX. pH variation in mobile phases containing formic acid, piperazine and tris as buffering systems and methanol as organic modifier.
In previous works a model to estimate the pH of methanol-aqueous buffer mobile phases from the aqueous pH and concentration of the buffer and the fraction of organic modifier was developed. This model was successfully applied and validated for buffers prepared from ammonia, acetic, phosphoric and citric acids. In the present communication this model has been extended to formic acid, piperazine and tris(hydroxymethyl)aminomethane buffers. Prior to the modelling work, the pK(a) values of the studied buffers at several methanol-water compositions were determined.
Subirats
Xavier
X
Departament de Química Analítica, Universitat de Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain.
Bosch
Elisabeth
E
Rosés
Martí
M
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005561:Formates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D000432:Methanol / Q000737:chemistry*; D008956:Models, Chemical; D000077489:Piperazine; D010879:Piperazines / Q000737:chemistry*; D015203:Reproducibility of Results; D014325:Tromethamine / Q000737:chemistry*
D005561:Formates; D010879:Piperazines; D014325:Tromethamine; C030544:formic acid; D000077489:Piperazine; D000432:Methanol