fT4(Free Thyroxine) ELISA Kit

This ELISA kit uses the Competitive-ELISA principle. The micro ELISA plate provided in this kit has been precoated with fT4. During the reaction, the fT4 in the sample or standard competes with a fixed amount of fT4 on the solid phase support for sites on the biotinylated detection Ab specific for fT4.

Excess conjugate and unbound sample or standard are washed away, and avidin-horseradish peroxidase (HRP) conjugate is added to each well of the microplate and incubated. A TMB Substrate Solution is then added to each well. The enzyme-substrate reaction is terminated with the addition of stop solution and the color changes from blue to yellow.

Optical density (OD) is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The concentration of fT4 in the analyzed samples can be calculated by comparing the OD of the samples with the standard curve.

Product Details

Assay type Competitive-ELISA
Format 96T/48T
Assay time 2.0h
Detection range 1.56-100 pg/mL
Sensitivity 0.94 pg/mL
Sample type &Sample volume serum, plasma and other biological fluids; 50μL
Specificity This kit recognizes fT4 in samples. No significant cross-reactivity or interference between fT4 and analogs was observed.
Reproducibility Both intra-CV and inter-CV are < 10%.
Application This ELISA kit applies to the in vitro quantitative determination of fT4 concentrations in serum, plasma, and other biological fluids.

Kit components and storage

An unopened kit can be stored at 2-8 ℃ for 1 month. If the kit is not supposed to be used within 1 month, please store the components separately according to the following conditions upon receipt of the kit.


The recovery of fT4 spiked at three different levels in samples throughout the range of the assay was evaluated in various matrices.

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