Stability of vitamin A in frozen sera.
We compared values for vitamin A measured in fresh sera with values obtained after storage at -20 degrees C for five to eight years. Loss of vitamin A from long-stored sera during the extraction step was eliminated by adding ascorbic acid to the extraction solvent, ethanol. Retinol-binding protein was also measured in the stored sera. Not only did vitamin A values remain stable during the years of storage, but also the correlation between concentrations of vitamin A and retinol-binding protein in the stored sera was typical of that observed with fresh sera.
D002851:Chromatography, High Pressure Liquid; D003124:Colorimetry; D005615:Freezing; D006801:Humans; D012177:Retinol-Binding Proteins / Q000032:analysis; D013997:Time Factors; D014801:Vitamin A / Q000097:blood*
D012177:Retinol-Binding Proteins; D014801:Vitamin A