↵1-a VPA and α-fluoro VPA (2 mM) were titrated in a 10% aqueous methanol solution (50 ml) with a standardized potassium hydroxide solution (10 mM) at room temperature. Values are the mean of three determinations.

↵1-b Log P values were determined from a standard curve which correlated HPLC retention times of a number of standard compounds with their literature log P values. The assay was conducted on a Hewlett Packard 1050 HPLC using a Hewlett Packard ODS2 column and acetonitrile-phosphate buffer (50 mM, 45/55 or 55/45, v/v, pH 2.5) as a mobile phase. Values are the mean of three determinations.