Reversed-phase ion-pair partition chromatography of phenylacetic, mandelic and pyridinecarboxylic acid derivatives.

Phenylacetic, mandelic and pyridinecarboxylic acids of physiological interest have been separated by ion-pair partition chromatography with 1-pentanol as stationary phase and tetrabutylammonium as counter ion in the aqueous mobile phase. The stability of the chromatographic system is very high and the support is spontaneously re-coated with stationary phase. Untreated plasma samples can be injected in relatively large volumes without serious loss of separating efficiency. A venting system was found efficiently to reduce disturbing early peaks on injection of biological samples.