Choline in plasma measured by liquid-chromatography with electrochemical detection

We have developed a simple, specific, and sensitive method for plasma choline measurement based on the HPLC procedure of Potter et al. (J Neurochem 1983; 41: 188) for the measurement of acetylcholine and choline in neuronal tissue. The effluent from a reverse-phase column is mixed with choline oxidase in a post-column reaction coil to produce hydrogen peroxide which is monitored electrochemically. Plasma samples are prepared by deproteinization with perchloric acid. Choline is recovered quantitatively from the plasma, but an internal standard (homocholine) is added to compensate for any variation in electrode response. Choline can be measured in plasma samples containing less than 1 mumole per litre of plasma; the method response is linear in the 1-20 mumol/L range. Catecholamines and ascorbic acid do not interfere. The chromatography, enzymatic reactions, and electrochemistry all contribute to the specificity of the method.