Suitable preanalytical conditions for vitamin C measurement in clinical routine

Abstract

Pre-analytical sampling conditions play an important role for the correct determination of blood concentrations of biomarkers and drugs in the clinical environment. In the context of daily clinical routine and clinical studies, oxidative stability in vitro should be carefully considered. Herein we report differences in vitamin C levels under commonly used handling and storage conditions and we propose a simple and efficient sampling protocol. Plasma and serum samples were analyzed by HPLC-UV and different handling-, timeand storage conditions were investigated in detail. Our findings show that protection from oxidation significantly prevented degradation under different storage conditions. The immediate separation of stabilized plasma from blood cells showed a protective effect on vitamin C stability. In addition, long-term storage of vitamin C was positively influenced by addition of protective agents, assuring stability up to six months. Oxidative degradation could affect not only vitamin C but also other small molecule metabolites and should therefore be intensively evaluated before implementation in daily clinical routine as well as in metabolomics studies.