EIA Kits

Quantitative, Competitive ELISA for Detection of Soluble Factors in a Variety of Species

RayBio® EIA kits utilize the principle of Competitive Enzyme Immunoassay, in which the target protein and a biotin-conjugated peptide bind competitively to a capture antibody. This assay requires only a single antibody, generating signal output by interaction of the biotinylated competitor with streptavidin-HRP. Thus, the EIA kits are particularly useful for detecting peptide hormones and other molecules for which no antibody pair exists, or for which antibody pairs cannot be developed.

Another important advantage of the EIA format is broad-species reactivity. For each kit, a peptide derived from a high-homology region of the target protein sequence serves as both the standard and the biotin-labeled competitor. RayBio® EIA kits are validated for rat, mouse, and human samples and have expected reactivity with many other species.

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EIA kit


  • Broad species reactivity
  • Strip plate format minimizes waste
  • Complete kit includes all necessary reagents
  • Highly sensitive and specific
  • Reproducible and reliable
  • Optimized for serum, plasma, and cell culture medium

Contents of Kit

  • 96-well strip plate (12x8)
  • Wash Buffer Concentrate (20x)
  • Standard Peptide 
  • Capture antibody
  • Positive control
  • Diluent Buffers
  • Biotin-labeled peptide
  • HRP-Streptavidin concentrate
  • TMB One-Step Substrate Reagent
  • Stop Solution

How It Works

Competition-based ELISA: How It Works

The samples and standards, which are spiked with biotinylated peptide, are pipetted into the assay plate; the target protein and the labeled peptide interact competitively with the capture antibody.  After washing, the bound biotin-peptide then interacts with streptavidin-HRP, producing a color development reaction. The intensity of colorimetric signal is directly proportional to the amount of biotin-peptide and inversely proportional to the amount of target protein in the samples.

Research Applications

  • Detection of quantitative protein levels in biological fluids
  • Validation of array results
  • Validation of biomarker discovery studies

Representative Data

Competition-based ELISA (EIA) Standard Curves

Why RayBiotech ELISA Kits?

  • We manufacture, not resell, ELISA kits. Right here in the USA.
  • Our ELISAs are ISO certified and validated for exceptional reproducibility. Read more about our quality control processes.
  • All RayBio® ELISAs are backed by our 90-day 100% satisfaction guarantee.
  • Discounts and incentives available for publications citing our products, and for product reviews.

Reference List

  • Bigelman E., Cohen L., Aharon-Hananel G., et al. Pathological presentation of cardiac mitochondria in a rat model for chronic kidney disease. PLoS One. 2018 Jun 11;13(6):e0198196. doi: 10.1371/journal.pone.0198196 [view publication]
    Product: Human ANGII EIA
    Sample Type: Plasma
  • Staedtke V., Bai R., Kim K., et al. Disruption of a self-amplifying catecholamine loop reduces cytokine release syndrome. Nature. 2018 Dec;564(7735):273-277. doi: 10.1038/s41586-018-0774-y [view publication]
    Product: Human ANP EIA
    Sample Type: Conditioned Media
  • Staedtke V., Bai R., Kim K., et al. Disruption of a self-amplifying catecholamine loop reduces cytokine release syndrome. Nature. 2018 Dec;564(7735):273-277. doi: 10.1038/s41586-018-0774-y [view publication]
    Product: Human ANP EIA
    Sample Type: Plasma
  • Elgarhy L. Abdelnabi N., Abdullatif A., et al. Circulating endothelial cells and serum visfatin are indicators of cardiovascular disease risk in psoriasis patients. Dermatologica Sinica, Volume 34, Issue 1, March 2016, Pages 20-25, http://dx.doi.org/10.1016/j.dsi.2015.07.004 [view publication]
    Product: Human Visfatin EIA
    Sample Type: Serum
  • Jambocus G., Saari N., Ismail A., et al. An Investigation into the Antiobesity Effects of Morinda citrifolia L. Leaf Extract in High Fat Diet Induced Obese Rats Using a (1)H NMR Metabolomics Approach. [view publication]
    Product: Human Ghrelin EIA
    Sample Type: Plasma
  • Kaya A., Orbak Z., Polat I., et al. Leptin and neuropeptide Y levels in newborns. J Pediatr Endocrinol Metab. 2016 Jan;29(1):21-5. doi: 10.1515/jpem-2015-0201. [view publication]
    Product: Human Neuropeptide Y EIA
    Sample Type: Plasma
  • Luedde M., Benz F., Niedeggen J., et al. Elevated Omentin Serum Levels Predict Long-Term Survival in Critically Ill Patients. Disease Markers Volume 2016, Article ID 3149243, 9 pages [view publication]
    Product: Human Omentin EIA
    Sample Type: Serum
  • Pisani D., Dumortier O., Beranger G., et al. Visfatin expression analysis in association with recruitment and activation of human and rodent brown and brite adipocytes. Adipocyte. 2016 Apr-Jun; 5(2): 186-195. doi: 10.1080/21623945.2015.1122854 [view publication]
    Product: Human Visfatin EIA
    Sample Type: Conditioned Media
  • Serin S., Bakacak M., Ercan O., et al. The evaluation of Nesfatin-1 levels in patients with and without intrauterine growth restriction. J Matern Fetal Neonatal Med. 2016 May;29(9):1409-13. doi: 10.3109/14767058.2015.1049524 [view publication]
    Product: Human Nesfatin EIA
    Sample Type: Serum
  • Ali F., Hassan N., Abdrabou R. Potential activity of Moringa Oleifera leaf extract and some active ingredients against diabetes in rats. International Journal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 1490 - 1500 [view publication]
    Product: Human C-Peptide EIA
    Sample Type: Serum
  • Ali S., Hamed E., Ayoub N., et al. Effects of different routes of nicotine administration on gastric morphology and hormonal secretion in rats. Exp Physiol. 2015 Aug;100(8):881-95. doi: 10.1113/EP085015 [view publication]
    Products: Human Gastrin EIA | Human Gastrin EIA
    Sample Type: Serum
  • Ashwini S., Bobby Z., Joseph M., et al. Insulin plant (Costus pictus) extract improves insulin sensitivity and ameliorates atherogenic dyslipidaemia in fructose induced insulin resistant rats: Molecular mechanism. Journal of Functional Foods. Volume 17, August 2015, Pages 749-760 [view publication]
    Product: Human Resistin EIA
    Sample Type: Plasma
  • Asmar A., Simonsen L., Asmar M., et al. Renal extraction and acute effects of glucagon-like peptide-1 on central and renal hemodynamics in healthy men. Am J Physiol Endocrinol Metab. 2015 Apr 15;308(8):E641-9. doi: 10.1152/ajpendo.00429.2014. [view publication]
    Product: Human ANP EIA
    Sample Type: Plasma
  • Barraco G., Luciano R., Manco M. Zinc-a2-Glycoprotein is Associated with Insulin Resistance in Children. [view publication]
    Product: Human ZAG EIA
    Sample Type: Serum
  • Bilir C., Engin H., Can M., et al. The prognostic role of inflammation and hormones in patients with metastatic cancer with cachexia. Med Oncol. 2015 Mar;32(3):56. doi: 10.1007/s12032-015-0497-y. [view publication]
    Product: Human Neuropeptide Y EIA
    Sample Type: Serum
  • Calik M., Cifci A., Sarikaya S., et al. Assessment of both serum S-100B protein and neuropeptide-Y levels in childhood breath-holding spells. Epilepsy Behav. 2015 Jun;47:34-8. doi: 10.1016/j.yebeh.2015.04.039 [view publication]
    Product: Human Pro-NPY/CPON EIA
    Sample Type: Serum

More references are listed per product on the individual product pages.