Application of a capillary electrophoresis method for simultaneous determination of preservatives in pharmaceutical formulations.

Preservatives are used to protect pharmaceutical formulations from microbial attack during the period of administration to the patient. Because of their biological activity, preservatives have to be identified and assayed according to the same rules as apply to active components. A number of methods for separation of preservatives are reported, to account for the heterogeneity of their chemical structures. A capillary electrophoretic method was devised for simple and simultaneous qualification and quantification of the preservatives most often included in pharmaceuticals, such as benzyl alcohol, parabens, phenol, m-cresol, chlorobutanol, thimerosal. After systematic method development, the electrophoretic conditions were defined as: 50 mM borate buffer pH 9.0 containing 20 mM SDS. Separations were performed at a temperature of 20 degrees C and with detection at 214 nm. Preservatives under examination can be analyzed within a 10 min run. The method was successfully validated and applied to the determination of preservatives in a number of pharmaceuticals. Results from the CE method were compared with those from reference methods.