Thyroxine （T4） is a tyrosine-based hormone produced by the thyroid glands. Thyroxine circulates throughout the body primarily bound to carrier proteins. Free T4 is converted to Triiodothyronine （T3） in peripheral tissues. The thyro-nines increase the basal metabolic rate，affect protein synthesis and increase the sensitivity of the body to catecholamines （such as adrenaline）. Cases of hypothyroidism，where the gland is insufficiently active，can be treated by administration of Thyroxine or a combination of Thyroxine and triiodothyronine. Sufficient levels of maternal Thyroxine is essential for fetal development，and inadequate production can cause irreversible fetal brain damage.Sample Type：Cell culture supernatants，serum，plasma，and tissueIntended Use：The Human Free Thyroxine BioAssay ELISA Kit is an enzyme-linked immunosorbent assay for the quantitative detection of Human Free Thyroxine concentrations in cell culture supernatants，serum，plasma，and tissue.Sensitivity：2pg/mlRange：4.5-86pg/mlSpecificity：Recognizes human Free Thyroxine.Sample Volume：100ul/wellTest Principle：This assay employs the Sandwich immunoassay technique. An anti-h FT4 monoclonal coating antibody is adsorbed onto microwells. FT4 present in the sample or standard binds to antibodies adsorbed to the microwells. Following incubation unbound sample or standard are removed during a wash step. a Biotinylated anti-h FT4 antibody is added and binds to FT4 captured by the first antibody. Following incubation unbound Biotinylated anti-h FT4 antibody is removed during a wash step. A Streptavidin-HRP is added and binds to Biotinylated anti-h FT4 antibody. Following incubation unbound Streptavidin-HRP is removed during a wash step. A colored product is formed in proportion to the amount of FT4 present in the sample. The reaction is terminated by addition of acid and absorbance is measured at 450nm. A standard curve is prepared from seven FT4 standard dilutions and FT4 sample concentration determined.Kit Components：Aluminium pouches with a Microwell Plate： 8x12Standard： 2xVialBiotinylated antibody： 2xVialStreptavidin-HRP： 2xVialAssay Buffer （25ml/Vial）： 2xVialWash Buffer Concentrate 20x （30ml/Vial）： 1xVialTMB Substrate Solution： 1x12mlStop Solution （12ml/Vial）： 1xVialPlate Covers- Adhesive strips： 3xstripsInstruction： 1xStorage and Stability：Store powder at 4°C liquid at -20°C. Store other components at 4°C. Stable for at least 6 months For maximum recovery of product，centrifuge the original vial after thawing and prior to removing the cap.
