REVERSED-PHASE LC ASSAY-METHOD FOR DEOXYCHOLATE IN INFLUENZA VACCINE

Sodium deoxycholate is used for the disruption of particles in the man ufacturing of some influenza vaccines. Residual deoxycholate in inacti vated vaccines is currently determined using a labour-intensive colori metric method which lacks complete specificity. An alternative assay m ethod for residual deoxycholate in vaccine preparations was developed using reversed-phase LC. Cholic acid was used as internal standard and the ratio of internal standard to test solute was used for all calcul ations. Prior to LC analysis, deoxycholic acid was concentrated by sol id-phase extraction, a procedure that also removed proteinaceous mater ial in vaccine samples. The clean-up/concentration procedure recovery was examined using untreated samples and was found to be quantitative. The linearity range of the LC method was between 3 and 200 mu g ml(-1 ), with a limit of detection of approximately 0.4 mu g on column. and a lower limit of quantitation of 1.6 mu g on column. Replicate assays during intra- and inter-day experiments gave acceptable levels of vari ability. The DCA content of samples from three lots of influenza vacci ne varied between 10 and 16 mu g ml(-1) These values were appreciably lower than those measured spectrophotometrically, indicating the highe r specificity of the LC method.