Patent ID: 7776544

Claim:
A method of quantifying vitamin A or D3, or vitamins A and D3, in an aqueous dairy sample within a few hours, comprising the steps of: (a) extracting the aqueous dairy sample with an alkaline metal salt and an extraction solvent comprising a mixture of a non-polar organic solvent and a polar organic solvent, to isolate vitamin A or D3, or vitamins A and D3 from the aqueous dairy sample into an organic fraction; and (b) determining the amount of vitamin D3 or vitamin A, or both vitamin D3 and vitamin A, in the organic fraction, wherein the vitamin is quantified with a monoclonal antibody which specifically binds to the vitamin, and wherein the non-polar organic solvent comprises an aliphatic hydrocarbon having from 4 to 10 carbon atoms, or a mixture thereof, and the polar organic solvent comprises a chloroalkane or ethyl acetate.