FA/VB9 (Folic Acid/Vitamin B9) ELISA Kit (UNES00006)

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ELISA Kit Technical ManualMSDS

FA/VB9 (Folic Acid/Vitamin B9) ELISA Kit

This ELISA kit uses Competitive-ELISA as the method. The microtiter plate provided in this kit has been pre-coated with FA/VB9. During the reaction, FA/VB9 in the sample or standard competes with a fixed amount of  FA/VB9 on the solid phase supporter for sites on the Biotinylated Detection Ab specific to  FA/VB9. Excess conjugate and unbound sample or standard are washed from the plate, and Avidin conjugated to Horseradish Peroxidase (HRP) are added to each microplate well and incubated. Then a TMB substrate solution is added to each well. The enzyme-substrate reaction is terminated by adding Stop Solution and the color change is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The concentration of   FA/VB9 in the samples is then determined by comparing the OD of the samples to the standard curve.

Assay typeCompetitive-ELISA
Assay time2.5h
Detection MethodColormetric
Detection Range1.56-100 ng/mL
Sensitivity0.94 ng/mL
Sample Volume50uL
Sample TypeSerum, plasma and other biological fluids


This kit recognizes FA/VB9 in samples. No significant cross-reactivity or interference between FA/VB9 and analogues was observed.

Typical Data

As the OD values of the standard curve may vary according to the conditions of the actual assay performance (e.g. operator, pipetting technique, washing technique or temperature effects), the operator should establish a standard curve for each test. Typical standard curve and data is provided below for reference only.

Concentration(ng/mL) O.D Average


Intra-assay Precision (Precision within an assay): 3 samples with low, mid range and high level FA/VB9 were tested 20 times on one plate, respectively.

Inter-assay Precision (Precision between assays): 3 samples with low, mid range and high level FA/VB9 were tested on 3 different plates, 20 replicates in each plate.

  Intra-assay Precision Inter-assay Precision
Mean (ng/mL)5.408.4635.724.868.0638.99
Standard deviation0.370.481.960.280.362.09
C V (%)6.855.675.495.764.475.36


The recovery of FA/VB9 spiked at three different levels in samples throughout the range of the assay was evaluated in various matrices.

Sample Type Range (%) Average Recovery (%)
Serum (n=5)85-10091
EDTA plasma (n=5)90-10195
Cell culture media (n=5)101-117108


Samples were spiked with high concentrations of FA/VB9 and diluted with Reference Standard & Sample Diluent to produce samples with values within the range of the assay.

    Serum (n=5) EDTA plasma (n=5) Cell culture media (n=5)
1:2Range (%)95-10988-10196-108
Average (%)10393101
1:4Range (%)95-10887-99109
Average (%)10294109
1:8Range (%)85-98100-111102-115
Average (%)91105109
1:16Range (%)99-11694-10998-110
Average (%)107101105

Kit Components & Storage

An unopened kit can be stored at 4'C for 1 month. If the kit is not used within 1 month, store the items separately according to the following conditions once the kit is received.

Item Specifications Storage
Micro ELISA Plate(Dismountable)8 wells X12 strips-20'C, 6 months
Reference Standard2 vials
Concentrated Biotinylated Detection Ab (100X)1 vial, 120 uL
Concentrated HRP Conjugate (100X)1 vial, 120 uL-20'C(shading light), 6 months
Reference Standard & Sample Diluent1 vial, 20 mL4'C, 6 months
Biotinylated Detection Ab Diluent1 vial, 14 mL
HRP Conjugate Diluent1 vial, 14 mL
Concentrated Wash Buffer (25X)1 vial, 30 mL
Substrate Reagent1 vial, 10 mL4'C(shading light)
Stop Solution1 vial, 10 mL4'C
Plate Sealer5 pieces
Product Description1 copy
Certificate of Analysis1 copy

FA/VB9 (Folic Acid/Vitamin B9) ELISA Kit (UNES00006) Assay procedure

    1. Set standard, test sample and control (zero) wells on the pre-coated plate and record their positions. It is recommended to measure each standard and sample in duplicate. Note: add all solutions to the bottom of the plate wells while avoiding contact with the well walls. Ensure solutions do not foam when adding to the wells.
    2. Add 50µL of Standard, Blank or Sample to their respective wells. The blank well is added with Sample / Standard dilution buffer.
    3. Immediately add 50 µL of Biotin-detection antibody working solution to each well.
    4. Cover with a plate seal and gently tap the plate to ensure thorough mixing. Incubate for 45minutes at 37°C.
    5. Aspirate or decant the solution from the plate and add 350µL of wash buffer to each welland incubate for 1-2 minutes at room temperature. Aspirate the solution from each well andclap the plate on absorbent filter paper to dry. Repeat this process 3 times. Note: a microplatewasher can be used in this step and other wash steps.
    6. Add 100µL of HRP Conjugate working solution to each well and over with a plate seal.Incubate for 30 minutes at 37°C.
    7. Repeat the aspiration/wash process 5 times according to step 5.
    8. Add 90µL of the Substrate reagent to each well and cover with a new plate seal. Incubatefor approximately 15 minutes at 37°C and protect from light. The reaction time can beshortened or extended according to the colour change, but not by more than 30 minutes. Whenapparent gradient appears in standard wells, terminate the reaction.
    9. Stop: Add 50µL of Stop Solution to each well (wells will develop a yellow color immediately).Note: Adding the stop solution should be done in the same order as the substrate solution.
    10. Determine the optical density (OD value) of each well immediately with a microplate readerset at 450 nm. In advance, preheat the instrument and set the testing parameters.
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