Determination of erythrocyte folate by competitive protein binding assay preceded by extraction.

Determination of the concentration of erythrocyte folate by means of competitive protein binding assay critically depends on the extraction procedure applied. Results will be influenced by variable factors such as the in vitro age of the blood samples, the degree of hemolysis, the presence of ascorbic acid, and the pH during extraction and elimination of proteins. The radioassay is strongly influenced by the pH of the final reaction mixture, the method used to separate free and protein-bound molecules, and the molecular configuration of the folates present. Based on experimental results presented, I describe a method for the determination of erythrocyte folate.