The 17β-Estradiol EIA kit is a colorimetric competitive enzyme immunoassay kit with results in < 3 hours. Absorbance is read at 405 nm. This kit offers specific and save non-radioactive quantification of estradiol with ready-to-use liquid color-coded reagents to reduce error. Kit mainly conatins GxR IgG Microtiter plate, Conjugate, Antibody, Assay buffer 3, Wash buffer concentrate, Standard, pNpp Substrate, Stop solution Miscellaneous/General: Biologically active estrogen, 17β-estradiol, is an important sex hormone, but also makes an important contribution to the high concentrations of estrogens, which are present in malignant breast tissues. It should have specific - low cross-reactivity to related steroids, 

Safe - non-radioactive enzymatic assay

Simple - liquid color-coded reagents reduce error

Reliable - reproducible results day-after-day and lot-after-lot

Thank you Ravi, I have one or two colleagues who express surprise at the claimed sensitivity of both these kits, around 2pg/ml, im especially keen to hear from anyone who has used either kit and their views on the sensitivity

Hi Peter, have you eventually find out more information about the EIA kit you mentioned before? I would be very interested in knowing your own experience about it, since I'm facing the same questions regarding the measurement of estradiol in bovine sera samples.... Abnova is a company which provides a specific ELISA kit for measuring estradiol in bovine samples but as you highlighted in your previous comment, I am also a bit surprised (even suspicious) from the sensitivity they claimed (5 pg/ml) particularly without any extraction process before the assay... So if you agree to share your experience about any kits assaying estradiol, it would be very nice and I would be very grateful to you! Thanks a lot in advance!

Hi Cecile, so my experience was mixed. The detection limit of the bluegen biotech kit was not sensitive enough. The Arbor assay kit will not work in sheep as it uses an anti sheep antibody, and results were all over the place. We did however manage to measure some fetal sheep samples (which have no IGG) and  got good reproducible results around 5pg/ml,  the standard curve looks good even lower. One key point however is the  samples must be diluted 1:20. So when Im talking 5pg/ml the original sample would have been 100pg/ml, this I believe puts the detection limit  around the same as other kits on the market. Having said that I would recommend the kit if you think your levels are going to be within the detection limit, its quick, simple and seems reliable. The online result calculator through the my assays site is useful too. Hope this helps. I haven't tried it in cows although may have the need to later on, so if find something that works let me know. Peter

Hi Peter, thank you very much for your answer. My researches are about the estral cycle in cows and the determination of estrus period. In this goal, I am interested in assaying progesterone and estradiol in cow sera. And unfortunately, I am facing some problems regarding the sensitivity of estradiol ELISA kits since, according to the litterature, the estradiol clinical level in cows during the estral cycle is around (and even under) 5 pg/ml with a peak around 10-15 pg/ml at the estrus time... After having written to you, I further studied the Arbor Assay EIA protocol and as you said , the main point is that they do strongly recommend to dilute at least 1/20 (I guess that, in doing so, any interferences due to other sera proteins or substances can be eliminated) and consequently, as you well explained, the limit of dectection is increased 20 times. This is eventually not suitable for me as they claimed a sensitivity in the well of about 2.2. pg/ml, meaning a clinical sensitivity of 44 pg/ml... For your kind information, I aslo studied the protocol of another EIA kit: the 17-beta-estradiol high sensitivity EIA kit, provided by EnzoLifeSciences (I know the products from this brand and they're good and reliable): they claimed a sensitivity of 15 pg/ml without any dilution but with a previous extraction (liquid-liquid or SPE). So I am going to try this one as I am used to work with their kits. By the way, for your kind information, we have already tested the progesterone EIA kit from EnzoLifeSciences in a parellelism study with 4 cow sera and it worked well with good linearity results, and allowed us to choose the working dilution at 1/20, without any extraction pre-process. Hope this little pieace of information could help you in the future! Anyway, it was a pleausre to have these discussions with you and share our knowledges on this topic. Don't hesitate to contact me again if you need! Best wishes, Cecile.

Dear Peter, i want to ask about your method. Which one do you prefer for steroid hormone measurement? serum or plasma? why are you choosing that? there are different recomendation which one is the best, and their argument were make sense. So I little bit confuse here. Thanks for response ^_^

Hi Anggadia,  in general we collect plasma, simply because it is suitable for most of our needs, we collect a lot of blood samples and the processing of plasma is quicker and simpler than serum.