Serum Vitamin B₁₂ Is Highly Unstable When Exposed to Light

Serum vitamin B₁₂ is highly unstable when exposed to light and can tolerate only a single absorbance reading before breaking down.Therefore,it is not possible to generate a standard curve for B₁₂.When the concentration of B₁₂ must be ascertained in a patient specimen,how should the technician go about doing so?

A) Calculate the concentration of B₁₂ directly from its absorbance in the solution using Beer's Law.
B) Determine the Km and Vmₐₓ of B₁₂ and apply those values to Ohm's Law to calculate the concentration of B₁₂.
C) Generate a standard curve using a more stable vitamin of similar chemical structure.
D) Measure transmittance of B₁₂ and create a standard curve using transmittance against concentration.