Ascorbate and dehydroascorbic acid as biomarkers of oxidative stress: validity of clinical data depends on vacutainer system used.

Ascorbate and dehydroascorbic acid are frequently used as biomarkers of oxidative stress, but their lack of stability ex vivo and rapid postsampling interconversion continue to result in erroneous reference values. One problem is the large variety of vacutainer devices used for blood sampling purposes and the basic question of plasma vs serum as matrix. This study acquired blood samples by using 9 different and commonly used vacutainer systems followed by acidic stabilization and analysis by a well-validated method with the purpose of identifying acceptable means of collecting samples for proper ascorbate/dehydroascorbic acid analysis. In comparison, K(3)-EDTA vacutainers were superior in maintaining low ex vivo oxidation of vitamin C.