Indirect photometric detection for determination of citrate in pharmaceutical matrices by ion chromatography

The development of a simple ion chromatographic method for the analysis of citrate in pharmaceutical matrices is described utilizing the technique of indirect photometric detection. A polymeric anion exchange column was used with a mobile phase consisting of an aqueous solution of trimesic acid (pH 10) and indirect detection at 280 nm. The developed method was precise and accurate with percent recoveries (+/-%RSD) of 99.3 +/- 0.97% and 98.2 +/- 0.25% at 6 and 12 micrograms of citrate injected. Linear detector response was found over the range 1-12 micrograms of citrate injected with a limit of quantitation of 0.26 microgram of citrate injected. The method is specific for tricarboxylic acids as most other ions were not retained by the column. Youden's robustness test, involving seven selected operating variables, showed that the method is fairly robust. A system suitability test was also performed. Many commercial USP and non-USP liquid and tablet formulations were assayed for citrate by the developed method and the results were found to be comparable with those obtained by the compendial method.