Formate, the salt form of formic acid, is a non-tetrahydrofolate (THF) -linked intermediate in one-carbon metabolism for carbon transfers driving methylation and cell proliferation. Formate is required for energy production in certain bacteria and, in humans, for synthesis of purines and thymidine for DNA. A shortage of formate results in spina bifida, anencephaly, and abnormally small ventricular walls during embryonic development. Excess formate occurs during methanol poisoning which can lead to metabolic acidosis and optic nerve damage. A disruption of the gut microbiome leads to excess formate, triggering intestinal inflammation and promote of colorectal cancer. When this excess formate enters the blood stream it fuels distant metastasis by allowing cancer cells to proliferate distant organs. Monitoring formate levels is an important indication of methanol toxicity, vitamin B12 deficiencies, and broad metabolic disorders.

Formate Assay Kit provides a simple, reproducible, and sensitive tool of measuring formate concentration in plasma, serum, cell lysates, urine, saliva, and other biological liquid samples. This assay is based on a coupled enzyme reaction. Formate is catalyzed by formate dehydrogenase to a colored product which can be quantified using a spectrophotometer or a microtiter plate reader at 450 nm. The optical density measured at 450 nm is directly proportional to the concentration of formate present in the sample.

• Microplate reader capable of measuring absorbance at 450 nm
• Precision pipettes to deliver 2 µL to 1 mL volumes
• Tubes to prepare sample dilutions
• 5 mL tubes
• Multi-channel pipettes to deliver 20 µL to 200 µL volumes
• Orbital shaker capable of 37°C
• MilliQ water or another type of double distilled water (ddH₂O)

1. Add 50 µL of the diluted Formate Standards or samples to the 96-well microtiter plate.
2. Add 50 µL Reaction Mix (+FDH) to each standard and one half of the paired sample wells, mix thoroughly.
3. Add 50 µL of Control Mix (-FDH) to other half of the paired sample wells. Carefully shake the plate for a few seconds to mix.
4. Seal the plate with a plate sealer or plastic wrap to reduce evaporation. Incubate the plate for 1 hour at 37°C with mixing in the dark.
5. Measure the absorbance at 450 nm using a plate reader.