The determination of choline in vitamin preparations, infant formula and selected foods by capillary zone electrophoresis with indirect ultraviolet detection.

A method for the determination of choline in vitamin preparations, infant formula and selected foods by capillary zone electrophoresis with indirect ultra-violet detection at 214 nm is described. the "free" choline in the vitamin preparations was simply extracted with water, the solutions filtered and analysed. The "free" and"bound" choline in the other products was extracted with methanol. The near dry extract was then treated with hot saturated aqueous calcium hydroxide to hydrolyse the "bound" choline before analysis. A 75 cm x 75 microns uncoated fused silica capillary column with an electrolyte consisting of 5 mM 1-methylimidazole, pH 4.5, and an operating voltage of 30 kV was used for all of the determinations. Using these conditions, choline migrates in less than 3 min and is well separated from the other components in the electropherograms. The tetramethylammonium ion was used as the internal standard. The instrument repeatability data for area calculation and migration time variation were good (coefficient of variation, CV, area calculation 1.4%, n = 10; CV for migration time variation 1.0%, n = 20). The level of detection for choline using this procedure is 5 mg/100 g.