Folate Plasma RBC Assay

Folate Assay (RBC or Plasma)


Per Sample

This 96-well format microbiological assay is considered to be one of the most effective methods for measuring folate levels in plasma, serum or red blood cells.


Non-UNC Users
Please note that UNC requires that an additional percentage for overhead be charged to the base rate for external sales. Please contact us for pricing.


Service Description

This assay measures the growth response of the bacteria L. casei (ATCC 7469) to folic acid. Since these bacteria require folate to grow, the growth response is directly related to the folate level in the blood or RBC sample. L. casei bacteria are used because they respond to the widest variety of folate derivatives. 5-methyltetrahydrofolate (5-methyl THF) is the major folic acid derivative found in plasma, serum, and red blood cells and is therefore used as the standard in the assay for biological samples. The coefficient of variation for this assay is 3.9%. The assay yields a linear response between 0 and 120pg.


Sample Processing

Plasma or Serum: Blood should be collected into a 4 mL EDTA or 6 mL heparin tube, inverted and placed on ice. Red cells are removed by centrifugation for 10 minutes at 2000 x g at 4°C. Plasma is collected and stored as 50 µL aliquots in 1.5 mL tubes at -80°C until ready to ship. Ship on dry ice for overnight delivery. Serum can be collected using SST-5 mL tubes. For accurate results, it is imperative you send the specified volume.

Red Blood Cells (RBC): Obtain RBCs from plasma as described above. Remove plasma completely. Pipet 100 µL RBCs into 1.1 mL freshly prepared 1% ascorbic acid (in water) in 1.5 mL tubes. Store immediately at -80°C.


Important Notes

  • Send the amount of sample requested and be sure to specify weights and volumes!
  • Sample tubes must be numbered clearly and simply, e.g. 1, 2, 3,…100, and accompanied by a sample key (which also must be emailed) describing the sample, sample volume or weight, and position in sample box.
  • Ship samples overnight delivery with enough dry ice to last 72 hours in case the package is delayed. It happens all too frequently.
  • If shipping a cell pellet, do not forget to determine the cell number, cell protein, or cellular DNA for data normalization prior to shipping. We do not do not perform those analyses.


Standard Operating Procedures

Folate Assay (RBC or Plasma)-Standard Operating Procedures


Shipping Information

Please contact us before you send your shipment. Send samples (in a styrofoam cooler on dry ice or ice packs overnight) with information to:
Steve Orena, Lab Manager
UNC Nutrition Research Institute
Metabolic Molecular Phenotyping Core-Kannapolis Facilities
500 Laureate Way, Room 2148
Kannapolis, NC 28081
T: (704) 250-5041


Have Questions? Contact Us.

Steve Orena, Lab Manager
Metabolic Molecular Phenotyping Core-Kannapolis Facilities
T: (704) 250-5041