ESTIMATION OF VITAMIN-D IN BABY FOODS WITH LIQUID-CHROMATOGRAPHY

According to Dutch food regulations, products like baby foods have to be enriched with vitamin D. A method was elaborated of estimating vita min D in baby foods. It included alkaline hydrolysis, extraction of th e vitamins and semi-preparative purification by liquid chromatography (LC) of the extract on a normal phase system. After this procedure, ex tracts were chromatographed on an analytical LC column coated with rev erse-phase material separating vitamin D2 from vitamin D3. Portions co ntaining vitamin D3, were spiked with vitamin D2 as internal standard for vitamin D3 and vice versa. In the Netherlands, baby foods were mos tly enriched with vitamin D3. Natural vitamin D2 was almost absent in these products. The respective detection limits for vitamin D2 and vit amin D3 were 350 IU/kg and 420 IU/kg for powdered baby foods, and 180 and 210 IU/kg for liquid baby foods. The repeatability for vitamin D3 for baby foods was 620 IU/kg (n = 10; [x] = 5500 IU/kg; s(r) = 220 IU/ kg; s(r,res) = 0,041) with an average recovery of 0,84 0,06 (P = 0,95; n = 16; s(r) = 0,12 and s(r,res) = 0,14). The method was suitable for assay of vitamins D2 and D3 in baby foods and was tested on 12 types of product, mostly based on milk or soya, from 4 manufacturers. One sa mple did not meet up to the requirements of the Dutch food regulations , and another did not seem homogeneous.