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

Abstract

Background: The pre-analytical stabilities of vitamins A, E, K, B1, B2, B6, B12, C, carotenoids and folates in whole blood were studied. The aim of this work was to provide clear and workable pre-analytical procedures specifying optimal delay before freezing for laboratories which perform themselves such analyses or which receive and transfer such specimens to referral laboratories. Methods: The stability of vitamins was studied in whole blood at room temperature after light exposure up to 24 h (vitamin C), 48 h (vitamins A, E, B1, B2, B6 and carotenoids) and 72 h (vitamins K, B12, red blood cell (RBC) and serum folates). Vitamin C stability after baseline acidification was analysed up to 48 h. Changes observed were compared to a clinical cut-off defined as total change limit based on a combination of analytical performance and within-subject variation. Results: Clinically and statistically significant changes occurred only in vitamins C (À22.5%), B6 (þ9.9%) and serum folates (À16.8%) concentrations after 6, 24 and 48 h, respectively. Vitamins A, E, K, B1, B2, B12, RBC folates and carotenoids showed good stability up to 48 or 72 h. Vitamin C in acidified serum conserved at room temperature appeared unstable. The optimal condition for acidified vitamin C conservation was at less than À20 C. Conclusion: The majority of vitamins remain stable for up to 48 h. Vitamin C quantification requires serum acidification followed by freezing as soon as possible. Freezing, respectively, within 12 h and 24 h for determination of plasma vitamin B6 and serum folates concentrations is recommended.

Effect of temperature and time delay in centrifugation on stability of select biomarkers of nutrition and non-communicable diseases in blood samples

“…A study that has looked at storage of several analytes up to a maximum of 96 h at 21°C CRP, retinol, and ferritin was reported to be stable; the mean concentration of folic acid however changed significantly over time, with the sharpest decrease (8.7%) in the first 2 h of storage ( 21 ). Vitamins A, E, K, B1, B2, B12, RBC folate and carotenoids were shown to be stable in whole blood when stored refrigerated or at RT even up to 48 or 72 h. Serum folic acid showed clinically and statistically significant changes in mean concentration after delayed centrifugation ( 22 ).…”

Appropriate Handling, Processing and Analysis of Blood Samples Is Essential to Avoid Oxidation of Vitamin C to Dehydroascorbic Acid

“…A number of studies have previously emphasised the importance of the collection and processing method for maintaining ascorbate stability in blood samples, with temperature and pH being the most important factors, particularly with respect to the anticoagulant used and perhaps also the acid precipitant, although the latter is less clear [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Our review of the literature of DHA concentrations reported in clinical cohorts (summarized in Table 3 ) has also highlighted that high concentrations of DHA are observed in all studies (except one [ 13 ]) that have used colourimetric or flourometric methods for detecting DHA [ 8 , 9 , 10 , 11 , 12 ].…”

A novel high-throughput method for supported liquid extraction of retinol and alpha-tocopherol from human serum and simultaneous quantitation by liquid chromatography tandem mass spectrometry

“…These data are in agreement with recently published data, albeit which studied stability in lithium heparin plasma as opposed to serum. 17 The LC-MS/MS method was compared to a HPLC-UV assay in routine clinical use, utilizing samples taken from patients on long-term parenteral nutrition support managed within an intestinal failure unit.…”