Stability of whole blood and plasma ascorbic acid

Abstract

The objective of this study was to evaluate the impact of pre-analytical factors on the short and long term stability of ascorbic acid (AA), the main form of vitamin C in whole blood and plasma. The effects of various anticoagulants, acidification, storage temperature and time were tested. A recently developed fast and sensitive HPLC method was used to measure AA levels. AA baseline values observed in heparin plasma were significantly higher than values observed in EDTA, citrate and Stabilyte plasma, as well as in serum. pH and temperature were identified as additional critical pre-analytical factors during the short, medium and long term handling and storage. Thus, assessment of reliable and accurate AA status in biological samples demonstrates to be highly dependent on whether the initial conditions during sample handling are controlled. In conclusion, heparin tubes should be used for blood sample collection. As AA is rapidly degraded, sample collection should be followed by immediate centrifugation and plasma acidification. To avoid further degradation during sample handling, samples should be stored at À701C without delay and analyzed within 80 days.

Overview of the in vitro stability of commonly measured vitamins and carotenoids in whole blood

“…6 As shown by many previous studies, vitamin C maintained at room temperature and exposed to light was dramatically unstable in whole blood. 4,22,23 It is well known that vitamin C in plasma or serum is readily oxidized by oxygen, high temperature, light, pH, ionic strength, solvents, oxidizing enzymes and interaction with iron and copper. 4 Results from our work showed a 22.5% decrease after 6 h in whole blood and more than a 50% decrease after 24 h. Stability of vitamin C depended in part on the type of anticoagulant used.…”

“…4,22,23 It is well known that vitamin C in plasma or serum is readily oxidized by oxygen, high temperature, light, pH, ionic strength, solvents, oxidizing enzymes and interaction with iron and copper. 4 Results from our work showed a 22.5% decrease after 6 h in whole blood and more than a 50% decrease after 24 h. Stability of vitamin C depended in part on the type of anticoagulant used. As described by Karlsen et al, heparin, EDTA and serum matrix gave the highest baseline concentrations of vitamin C. 4 However, in each matrix, vitamin C concentration decreased rapidly and the more stable matrix seemed to be heparin as the authors reported a loss of less than 5% at 3 h in whole blood.…”

“…Vitamins are particularly known to be sensitive to numerous chemical and physical factors such as oxidation, high temperature, light, pH and ionic strength. 4 A number of studies evaluated the impact of storage conditions on the quality of results for common biochemical analytes but existing data on the stability of vitamins in whole blood are sparse and somewhat contradictory. [4][5][6][7] Available studies are dedicated to one or to a few vitamins in heterogeneous conditions including different storage times, temperatures and matrix.…”

Enhancing translational research in paediatric rheumatology through standardization

“…31 Ascorbic acid has also been used as a QC marker for blood pre-centrifugation delay and serum storage conditions owing to its intrinsic instability. 32,33 Pitfalls are readily apparent in even these examples of anlaytes proposed as potential QC tools.…”

Rapid, sensitive and simultaneous determination of ascorbic and uric acids in human plasma by ion-exclusion HPLC-UV

“…However, only a few studies have described the simultaneous determination of AA and UA. Several pre-analytical procedures are required for an accurate and reliable determination of these two antioxidants in human plasma, mainly because AA is extremely sensitive to oxidation and degradation during blood sampling, handling, storage, and analysis [20,21]. Additionally, it is necessary to stabilize the plasma samples by protecting them from light and high temperatures, as well as acidifying the samples before storage, particularly when it is not possible to immediately perform the analysis.…”