Stability of Folate and Vitamin B₁₂ in Human Serum after Long-Term Storage: A Follow-Up after 13 Years

Figure 4

Correlation between the mean vitamin B₁₂ concentrations at and after storage for 1, 8, and 13 years at −70°C. The correlation lines have the following equations: y = 0.829x + 2.80 , y = 0.600x + 33.7 , and y = 0.401x + 48.5 for 1, 8, and 13 years, respectively.