The serum is pre-treated and diluted with a buffer mixture,and then sampleswere transferred in the wells of a microtiter plate [PLATE] coated with Lactobacillusdelbrueckii subsp.lactis.The addition of vitamin B12 in either standards [STD] or samples gives a vitamin B12-dependent growth response until vitamin B12 is consumed. After incubation at 37°C for 44 - 48 hours, the growth of Lactobacillusplantarum is measured turbidimetrically at 610 - 630 nm (alternatively at 540 - 550 nm) in an ELISA-reader and a standard curve isgenerated from the dilution series. The amount of vitamin B12 is directly proportional to the turbidity. Sample Types: serum. Range: 6 - 54 ng/L. Sensitivity: 6 ng/L. Time: 48 hours ? The Eagle Biosciences Vitamin B12 is a microtiter plate test kit based on a microbiological assay which measures the total Vitamin B12 content in serum.The test kit contains all required reagents, e.g. standard,medium and microtiter plate coated with a specific microorganism,sufficient for 96 determinations including standard curves. An ELISA reader is required for evaluation of the Vitamin B12 content. The Vitamin B12 Assay Kit is for research use only.