Ion-pair partition chromatography of mefenamic acid with tetraalkylammonium cations: development of analytical method from extraction data

: The ion-pair partition properties of mefenamic acid with the methyl, ethyl, n-propyl, and n-butyl homologs of tetraalkylammonium cation were studied in relation to a model of an assay procedure for acidic drugs. Variables studied included identity and concentration of pairing ion and composition of extracting solvents. Resulting data were used to develop a partition chromatographic assay procedure. Standard recoveries averaged 99.01 +/- 0.82%. Assays of commercial capsules were reproducible.