Reversed-phase, ion-pair high-performance liquid chromatographic separation of aminoethanol, choline and related compounds, and a direct, quantitative high-performance liquid chromatographic assay for choline in plants

Determination of (2,3-epoxypropyl)trimethylammonium chloride, (3-chloro-2-hydroxypropyl)trimethylammonium chloride, and (2,3-dihydroxypropyl)trimethylammonium chloride by capillary electrophoresis

Capillary electrophoresis (CE) is a powerful technique to determine (2,3-epoxypropyl)trimethylammonium chloride, (3-chloro-2-hydroxypropyl)trimethylammonium chloride and their hydrolysis product (2,3-dihydroxypropyl)trimethylammonium chloride in complex matrices. The separation was performed in a 180 mM copper(II) sulphate-4 mM formic acid buffer at pH 3. The UV inactive target compounds were detected by indirect UV detection at 215 nm with a reference wavelength of 300 nm--copper(II) being the chromophor. The results were compared to data acquired by ion-pair HPLC with perchlorate as ion pair former in a 1 M aqueous sodium perchlorate solution in 0.2 mM phosphoric acid (pH 3.4) on a RP 18 column and refractive index detection as reference method. Results of both methods are in good agreement.

Detection of choline and acetylcholine in a pharmaceutical preparation using high-performance liquid chromatography/electrospray ionization mass spectrometry

A sensitive, rapid, and specific method for the detection of choline and acetylcholine in a pharmaceutical preparation is described. The method employs a perfluorinated carboxylic acid as ion-pairing reagent, post-column addition of a surface tension reducing agent and mass spectrometric detection using either selected ion monitoring (SIM) or selected reaction monitoring (SRM) modes. The resulting chromatographic performance is comparable or superior to methods reported previously in both quality of the separation and sensitivity when using mass spectral detection, with the added advantage of reduced cycle time. Acetylcholine is easily and rapidly separated from its major decomposition product choline. The method was able to detect acetylcholine and its primary degradation product choline at the 30 fmol level, with an analysis time of less than 6 min.

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.