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Product Name: b-HCG

# of Samples: 1 x 96 Assays

Intended Use: Immunoenzymatic colorimetric method (ELISA) for quantitative determination of b-HCG in serum or plasma.

Introduction: Human chorionic gonadotropin (hCG) is a glycoprotein hormone secreted in pregnancy, that is made by the embryo soon after conception and later by the syncytiotrophoblast (part of the placenta). Its role is to prevent the disintegration of the corpus luteum of the ovary and thereby maintain progesterone production that is critical for a pregnancy in humans. hCG may have additional functions, for instance it is thought that it affects the immune tolerance of the pregnancy.
Pregnancy tests measure the levels of hCG in the blood or urine to indicate the presence or absence of an implanted embryo. In particular, pregnancy tests employ an antibody that is specific to the β-subunit of hCG (βhCG). This is important so that tests do not make false positives by confusing hCG with LH and FSH.
βhCG is also secreted by some cancers including teratomas, choriocarcinomas. But, elevated levels cannot prove the presence of a tumor, and low levels do not rule it out.

Principles of the assay: The b-HCG assay is based on simultaneous binding of human b-HCG to two monoclonal antibodies; one is immobilized on the microplate, the other is soluble and conjugated with horseradish peroxidase (HRP). Microtiter strip wells are precoated with anti-b-HCG IgG antibodies. b-HCG in samples and standards binds to the immobilised antibodies on the surface of the microtiter wells and the second, soluble anti-b-HCG antibody-enzyme conjugate binds to the immobile antibody-b-HCG-complex during the first incubation. Afterwards a washing step is performed. The immune complex is visualized by adding Tetramethylbenzidine (TMB) substrate, which gives a blue reaction product. The intensity of this product is proportional to the amount of b-HCG in samples and standards. Sulphuric acid is added to stop the reaction. This produces a yellow endpoint colour. Absorption at 450 nm is read using an ELISA microwell plate reader.

Storage and Stability: The closed reagents are stable up to the expiry date stated on the label when stored at 2...8 °C.

Limitations of the Test: Bacterial contamination or repeated freeze-thaw cycles of the specimen may affect the absorbance values.

References Wisdom, G.B., Clin. Chem. (1976) 22/8, 1243 – 1255Shome, B. and Parlow, A.F.; J. Clin. Endocr. Metab. (1974) 39, 199 – 202Uotila, M., Ruoslahti, E., Engvall, E.J., J. Immunol. Methds (1981) 42, 11 – 15Acosta, A.A.M.D. and Wright, G.L., Journal of Clinical Immunoassays (1983) 6, 41Cohen, K.L., Metabolism (1977) 26, 1165 – 1177Lindstedt (1982) Scand. J. Clin. Lab. Invest 42, 201Chien (1987) J. Clin. Endocr. Metab. 64, 313

Additional Information

Name beta-HCG
Related Product Names b-HCG
Molecular Weight 0.5
Storage The closed reagents are stable up to the expiry date stated on the label when stored at 2...8 °C.
Datasheets/Manuals Printable manual for GWB-519AAA
Intended Use Research Use Only