Validation study of the VitaKit A test kit for the determination of vitamin A in fluid milk (2% fat) for routine...

A validation study of VitaKit A for quantitation of total vitamin A in 2% fluid milk was carried out according to the guidelines provided by AOAC INTERNATIONAL. The VitaKit A was compared, in terms of repeatability and accuracy, with the U.S. Food and Drug Administration-Interstate Milk Shippers HPLC reference method for determination of total vitamin A in fluid milk with 2% fat. The data obtained by the VitaKit A method are in excellent agreement with the data obtained by the HPLC reference method. Further, a low LOD (0.33 international unit/mL) was obtained for the VitaKit A method; the presence of interferents, like cholesterol and vitamin D3, in the milk had minor influence on the quantitation of total vitamin A by the VitaKit A method. The VitaKit A test kit was found to be stable for 1 year from the date of manufacture when stored at 2-8 degrees C. The method requires 2 h processing time, compared to 1-2 days for the HPLC reference method. The results of this validation study clearly demonstrate that the VitaKit A method is reliable, rapid, and accurate for the quantitation of total vitamin A in fluid milk containing 2% milk fat. An independent study by Q Laboratories Inc., Cincinnati, OH, under the validation guidelines of AOAC INTERNATIONAL, confirmed these findings.