Ion-exchange liquid chromatography method with indirect UV detection for the assay of choline in pharmaceutical...

A high-performance liquid chromatography (HPLC) method coupled with indirect UV spectrophotometric detection was developed for the routine control of pharmaceutical preparations containing choline. Optimization of the HPLC system using silica-based cation exchange columns was focused on the combination in the mobile phase between a UV transparent co-ion and a UV active cationic probe. The selected mobile phase consisted of a mixture of ethanol-ammonium acetate buffer (100 mM, pH 5.0) (20:80, v/v) containing 0.3 mM of 3-hydroxytyramine as chromophoric probe; UV detection was operated at 280 nm. The HPLC system provided full selectivity with regard to the multi-ingredient pharmaceutical matrices tested. Quantitative analysis was validated by testing linearity of the method between 50 and 150% of the theoretical content (coefficient of correlation greater than 0.99) and repeatability (relative standard deviation less than 2.5%; n = 5).