We obtain inconsistant low Vit A palmitate recoveries from infant milk formula (spray dried). Results (normal phase HPLC) from different accredited laboratories give inconsistant results.
Vitamin A palmitate is added to an infant milk formula base prior to homogenization, pasteurization and spray drying.
Any assistance will be much appreciated. Thank you
Vitamin A is moderately heat sensitive, more sensitive to light and oxidization processes. Could it not perhaps be influenced by the processing?
Hi Desiree, the formula is fortified with Ferrous sulphate, but it also contains antioxidants such as ascorbic acid and Vit E acetate. Those concentrations are still within spec.
Fat in milk may interfere with HPLC separation. It is better to saponify, determine retinol concentration and convert to vitamin A palmitate to express it in weight units (not necessary for international units mmol/L)
Thank you, Maria. We have been using an HPLC method where the sample is incubated with papain enzyme which is supposed to release Vit A from proteinaceous miscelles. Thereafter the Vit A palmitate (or acetate) is extracted into iso-octane. Do you think that the fat in this solvent causes low recoveries? Thank you for your input!
I was thinking about the fat in the milk (formula), that may clog the HPLC column. I used normal phase HPLC separation and hexane extraction in 1970-ies, later it was always reverse phase HPLC, hexane extraction (after saponification in case of milk or tissues), vacuum evaporation and reconstitution with solvent mix compatible with mobile phase. The use of antioxidants during extraction is advisable to prevent oxidation losses, as well as working with minimum light.
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