Choline and carnitine are quaternary amines that are synthesized in the body or consumed through the diet. Choline is critical for cell membrane structure and function and in synthesis of the neurotransmitter acetylcholine. Carnitine mediates cellular energy via transport of fatty acids in and toxic by-products out of cells. While the human body produces both of these micronutrients, dietary supplementation of choline is necessary for good health and additional carnitine intake may be beneficial for some individuals. Current methods for determination of total choline and carnitine in foods are lengthy and require multiple hands-on steps in order to extract and hydrolyze the many forms present in dairy and grain products. Hydrolysis of choline and carnitine esters requires treatment with acid, base, or enzymes in order to release choline and carnitine ions. In this work, traditional acid and enzymatic hydrolysis procedures were compared to microwave-assisted acid hydrolysis, and the conditions optimized to provide complete sample hydrolysis and recovery of total choline from whole milk powder, whole egg powder, infant formula, and soy flour matrices. The extracts were analyzed using liquid chromatography on a mixed-mode column with isotope dilution mass spectrometry detection to achieve simultaneous quantification of total choline and free carnitine.
Citation: Journal of Aoac International
Pub Type: Journals
choline, carnitine, microwave, food, mass spectrometry, isotope dilution