Newly Updated Cayman Estradiol ELISA Kit

A critical shortage of the antibody used in Cayman's Estradiol ELISA Kit (Item No. Cay582251) prompted the need for a replacement Estradiol ELISA Kit (Item No. Cay501890). Cayman's scientists developed a new antiserum with less cross reactivity compared to the previous kit and changed the sample preparation/extraction protocol to a simpler and less hazardous format that provides improved specificity. Synthetic 17β-estradiol and samples of human plasma were tested side by side in both kits to compare performance.

NEW: Estradiol ELISA Kit

Item No. Cay501890

  • Measure estradiol in plasma and serum samples
  • Assay 24 samples in triplicate or 36 samples in duplicate
  • Measure estradiol levels down to 20 pg/ml
  • Incubation: 2 hours | Development: 60 minutes | Read: Colorimetric at 414 nm



The new kit offers sensitivity values comparable to those of the previous kit. However, the concentrations of analyte or assay values of the new kit are detectable over a wider assay range compared to the previous kit.



Sample Preparation/Extraction Protocol

Plasma and serum samples may require extraction prior to quantification in the assay to eliminate potential substances like bulk proteins or lipids that may interfere with steroid quantification. Extraction can also help concentrate the sample to within the measurement range of the assay. Cayman Chemical updated the extraction protocol in the new kit. This new protocol requires a single precipitation step with methanol, instead of the repeated liquid/liquid extraction steps needed with methylene chloride, which carries greater hazardous materials precautions.

Previous Kit (Item No. Cay582251) Protocol New Kit (Item No. Cay501890) Protocol
Methylene chloride used at 4X sample volume Methanol used at 4X sample volume
Extraction procedure is repeated 2 times Precipitation procedure is one step


Cross Reactivity

The new kit demonstrates improved specificity for estradiol with minimal detection of estradiol 3-glucuronide, estrone, estradiol 3-sulfate, and estradiol 17-glucuronide.

Compound Previous Kit (Item No. Cay582251) New Kit (Item No. Cay501890)
Estradiol 100% 100%
Methoxyestradiol not tested 2.5%
Estradiol 3-(β-D-Glucuronide) 14% 2.3%
Estrone 12% 1.38%
2-Hydroxyestradiol not tested 1.3%
Estriol 0.30% 1.0%
Estradiol Benzoate <0.01% 0.7%
Estradiol 3-sulfate 14.5% 0.53%
Ethynyl Estradiol 0.05% 0.14%
5-Androstan-17β-ol-3-one 0.02% 0.06%
17α-Estradiol <0.01% 0.04%
5α-dihydro Testosterone 0.06% 0.04%
Androstenediol 0.02% 0.03%
Testosterone <0.01% 0.03%
Estradiol 17-sulfate <0.01% 0.02%
Estradiol 17-(β-D-Glucuronide) 10% 0.02%


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