Determination of plasma ascorbic acid by high-performance liquid chromatography with ultraviolet and electrochemical detection.

A convenient and reliable reversed-phase liquid chromatographic method for the routine determination of ascorbic acid with ultraviolet detection is described. This system avoids the use of modifier and ion-pairing reagent. The mobile phase consists of 20 mM ammonium dihydrogenphosphate with 0.015% metaphosphoric acid. This method enables the detection of plasma ascorbic acid at a concentration of 120 ng/ml within 5 min. The recovery and reproducibility were above 95%. A comparative study was also performed using ultraviolet and electrochemical detectors. Excellent agreement was observed between the two detection modes, with a correlation coefficient of 0.99. In addition, the storage conditions and stability of ascorbic acid in plasma and whole blood were investigated. The results showed that ascorbic acid was more stable in whole blood when stored below 4 degrees C.