Simultaneous determination of vitamins A, E and 25-OH-vitamin D: Application in clinical assessments

Objective: To optimize an HPLC method for the simultaneous determination of vitamins A, E and 25-OH-vitamin D. Methods: Modifications include sample volume, internal standard, temperature, detection and injection volume. Results and discussion: Validity was supported by performance in interlaboratory exercises. Utility and versatility in clinical practice were assessed in outpatients and hospitalized subjects. The method was shown to be accurate and reliable for the simultaneous determination of vitamins A, E and 25-OH-vitamin D in serum throughout the entire range of clinically relevant concentrations.