Abstract
Purpose: There is good evidence that ascorbic acid (AA) status influences the onset of post-operative complications in intensive care patients. Light and room temperature cause the spontaneous oxidation of AA. Therefore, the stability of AA during modified sample preparation was investigated. Design: Prospective, single centre study. Methods: The AA plasma concentration was analysed in arterial and venous blood with added ethylene-diamine-tetra-acetic acid (EDTA) from 165 subjects. In addition, EDTA or heparin was added as an anticoagulant in venous blood of 79 subjects. Analyses were carried out using high performance liquid chromatography with ultraviolet detection. Results: In samples of arterial and venous blood with added EDTA it was observed that precision declined with increasing concentrations of AA. In venous samples with added heparin the correlation was low compared with venous samples with EDTA. Conclusion: Any change in our standard method of specimen collection (venous blood with added EDTA) results in AA plasma concentrations with questionable reliability.