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Abstract
A method involving ion-exchange chromatography and titration was developed. A diluted sample was run through a cation-exchange resin column. After the eluate was boiled, it was titrated with 0.02 N NaOH to find the sodium citrate content (Titration I). An equal volume of the diluted sample was eluted through an anion-exchange resin column and the eluate was titrated with 0.02 N HCl to assay for total sodium bicarbonate and sodium citrate (Titration II). Subtracting the result of Titration I from that of Titration II, gave the sodium bicarbonate content. The cation-exchange chromatography step was validated previously. The anion-exchange chromatography step was validated by assaying pure sodium bicarbonate and sodium citrate separately. The overall percent recoveries (+ SD) were 98.9 + 0.2% for sodium citrate and 98.1 + 0.1% for sodium bicarbonate (n = 3). Average percent recoveries (+ SD) from synthetic mixtures of the two salts were (n = 4): 99.3 + 0.5% for sodium citrate and 98.0 + 1.2% for sodium bicarbonate. The method was applied to commercially available formulations.