Fingerprinting Krill Oil by 31P, 1H and 13C NMR Spectroscopies

The detailed analysis of krill oil is of importance to be able to differentiate other oils, identify adulterated products, and provide the highest quality associated with its beneficial health effects. The objective of this study was to demonstrate the usefulness of the combination of P-31, H-1 and C-13 nuclear magnetic resonance (NMR) spectroscopies to characterize the krill oil profile. It was found that in contrast to fish oil, where eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) fatty acids are found in triacylglycerol, krill oil is characterized by a more asymmetric fatty acid distribution with a higher polyunsaturated fatty acids PUFA content in the sn-2 position of phospholipids and lower amounts in triacylglycerol. Besides the typical asymmetric fatty acid composition, several other markers were investigated for krill oil origin test. The validation of the P-31 NMR spectroscopic method regarding major phospholipid species was performed according to the Good Laboratory Practice (GLP) and International Council for Harmonisation (ICH) guidelines. The method was characterized by high sensitivity, accuracy, and reproducibility. Interlaboratory testing showed satisfactory robustness regardless of the type of NMR equipment used by different laboratories. High-resolution NMR spectroscopy has proven to be a convenient and exact method for providing a characteristic fingerprint of krill oil. By this technique, clear distinctions to other oils can be made through qualitative and quantitative analysis of krill oil.