The application of a simple, selective, precise, and accurate thinlayer chromatographic method for quantification of l-carnitine in dietary food supplements, including drinks, capsules, and tablets, was reported. The high-performance thin-layer chromatography (HPTLC)-cellulose plates as stationary phase, and mixture: methanol-water-glacial acetic acid (10:2:0.1 ν/ν) as mobile phase were chosen. The chromatograms were analyzed densitometrically in the maximum absorption at 420 nm, after ninhydrin-based derivatization reaction. The analytical procedure has been validated in terms of basic parameters, such as linearity, precision, and accuracy. The developed method is characterized by LOD sensitivity of 2.51 μg per spot, as well as LOQ for 7.61 μg per spot and high accuracy established by recovery studies between 99.50% and 103.60 % with good precision (RSD below 1.55%). Presented TLC method illustrated suitability for routine qualitative and quantitative analyses of l-carnitine in dietary supplements.
M. Kagawa, Y. Machida, H. Nishi, J. Haginaka, Chromatographia 62 (2005) 239–244.