Analysis of marine dietary supplements using NMR spectroscopy

The objective of this study is the qualitative and quantitative analysis of encapsulated fish oil supplements by utilizing high-resolution multinuclear (H-1, C-13, P-31) and multidimensional NMR spectroscopy. By employing sophisticated 2D NMR experiments, such as HSQC-TOCSY, band-selective HSQC and semi-selective constant-time HMBC we performed a systematic two-dimensional analysis of the various components in fish oil. The present analysis offered a solid proof and confirms earlier assignments based on model compounds. Moreover, this study revealed the presence of n-1 acyl chains and trans fatty acids in concentrations ranging from 1.9-2.9% and 3.7-5.2%. Application of P-31 NMR spectroscopy to the analysis of micro-constituents in fish oil supplements allowed the fast and accurate determination of additional minor compounds in it. Quantitative determination of the various compounds in the supplements was achieved upon integration of the appropriate NMR signals in the relevant spectra.