Choline is a water-soluble essential nutrient and is a component of phospholipids that are a major constituent of cell membranes.  Choline is a precursor of the neurotransmitter acetylcholine found in living organisms.  Their presence is related to several life phenomena and diseases, and it is important to be able to measure the ratio of these molecules. Typically, reversed phase chromatography is used for analyzing choline and acetylcholine.  Due to their hydrophilic nature, an ion-pair reagent is utilized for the mobile phase. A post-separation affinity column modified with choline oxidase / acetylcholine esterase, as well as, an electrochemical detector for monitoring hydrogen peroxide are needed to enable highly sensitive analysis. In order to simplify the analysis, a new LC/MS method was studied. An ion chromatography column, with polyvinyl alcohol base packing material modified with carboxyl groups, was used for the LC. The optimized eluent condition was 4 mM nitric acid / acetonitrile =70/30.  The flow rate was 1.0 mL/min, and the column temperature was 30 �C. ESI-MS was used for detection. The mixed standard solution of choline and acetyl choline (10 ng/mL of each) was analyzed. The retention times of choline and acetylcholine were 5.0 and 6.0 minutes, respectively. Both peak shapes were sharp with baseline separation, and the calibration curve was linear. Our described LC/MS method should be more facile with higher selectivity than the previous method.

LC/MS analysis of choline and acetylcholine in living organisms using polymer-based cation IC column

248th National Meeting (2014)

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