Serum samples are diluted with a buffer solution. The diluted samples are added into the microtiter plate wells [PLATE] coated with Lactobacillus rhamnosus which metabolizes folic acid.The addition of folic acid in either standards [STD] or samples gives a folic acid dependent growth response until it is consumed.After incubation at 37°C for 48 hours,the growth of Lactobacillus rhamnosus is measured turbidimetrically at 610-630 nm (alternative at 540-550 nm) in an ELISA-reader and a standard curve is generated from the dilution series.The amount of folic acid is directly proportional to the turbidity. Sample Types: serum. Range: 0.04 - 0.32 μg/L. Sensitivity: 0.04 μg/L. Time: 48 hours ? The Eagle Biosciences Folic acid is a microtiter plate test kit based on a microbiological assay which measures the total folic acid 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 folic acid content. The Folic Acid Assay kit is For Research Use Only.