High-performance liquid chromatographic determination of vitamin D3 in fish liver oils and eel body oils

Identification and determination of vitamin D3 (or D2) and 25-OH-D3 in fish liver oils and eel body oils were carried out. By co-chromatography on HPLC, UV spectra and/or GC-MS, vitamin D3 was identified in naturally occurring fish liver oils and eel body oils, whereas a drop of fish liver oil contained supplemented vitamin D2. 25-OH-D3 was identified only in skipjack liver oil. The HPLC method proposed in a previous report (Takeuchi, A. et al. (1984): J. Nutr. Sci. Vitaminol., 30, 11-25) was confirmed to also be useful for determination of vitamin D3 (or D2) in fish liver oils and eel body oils. The assayed values of vitamin D3 in skipjack and tuna liver oils were 57,760 and 16,200 IU/g, respectively, which were much higher than those in cod and pollack liver oils. The assayed values of vitamin D3 in eel body oils were very low (16-43 IU/g) and showed no appreciable change despite differences in the farming conditions. Determination of 25-OH-D3 in skipjack oil was performed by using HPLC, and the assayed value was 1.8 micrograms/g. This was about 1/800 lower than that of vitamin D3.