Long-term (in)stability of folate and vitamin B-12 in human serum

作者：Jansen Eugene H J M^*; Beekhof Piet K; Cremers Johannes W J M; Schenk Erna

来源：Clinical Chemistry and Laboratory Medicine, 2012, 50(10): 1761-1763.

DOI：10.1515/cclm-2012-0108

• folate
• stability
• storage
• vitamin B-12

Background: In epidemiological research it is very important to test the stability of biomarkers as a function of both storage time and temperature. In this study the stability of both folate and vitamin B-12 in human serum samples have been tested after storage at three different temperatures up to 1 year.
Methods: Serum samples of 16 individuals were used in this study. The concentration of folate and vitamin B-12 has been determined at T=0 and at several time points up to 1 year after storage at -20 degrees C, -70 degrees C and -196 degrees C. The statistical difference from the initial value at T=0 were determined with a t-test.
Results: Folate in serum samples remained stable at -70 degrees C but was not stable during storage at -20 degrees C. A fast decrease was observed after Day 4 which resulted in a stable level of about 60% of the original value measured at T=0 ( p<0.001). The rank order of folate concentration in the samples, however, was not affected. The stability of vitamin B-12 was good at all temperatures tested.
Conclusions: Measurements of folate concentrations in serum stored at -20 degrees C are not reliable. The rank order, however, was not changed. Vitamin B-12 was stable at all temperatures tested. For both folate and vitamin B-12 storage at -70 degrees C is sufficient to maintain the original concentration for 1 year. Storage at -196 degrees C in liquid nitrogen is not necessary for these nutrients.

• 出版日期2012-10