Determination of vitamin D3 in margarines, oils and other supplemented food products using HPLC.

The vitamin D3 content of high fat foods, such as margarines and oils, was determined by liquid chromatography. The method involved sample saponification and an extraction process, in which the purification of the non-saponifiable matter was the critical step. A semi-preparative straight-phase clean up procedure was used to produce an adequately purified sample solution prior to the final analytical quantification step. Vitamin D2 was used as internal standard when estimating the vitamin D3 content. The overall recoveries depended on the fat content of the food sample and varied from 40% for margarines to 80% for low-fat products at a concentration of about 10 micrograms/100 g. The minimum detectable amount was 0.36 ng vitamin D3. The mean relative recovery of vitamin D3 in relation to vitamin D2 was calculated to be 0.97.