## ELISA hormon assay

Debate and discussion of any biological questions not pertaining to a particular topic.

Dr.Stein
King Cobra
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### ELISA hormon assay

Anyone could help me how to configure or convert the OD value to the hormone level (ng/mL or ng/dL)?

I used to work with RIA and the manual (insert) mentions how to calculate from CPM to the hormone level but I cannot find it in ELISA manual insert

Vagabond
Posts: 59
Joined: Mon Feb 19, 2007 7:01 pm
Quickly you plot the OD reading for you standard (say on the Y axis) similar to RIA and then across the X axis you plot you concentrations.

Draw the line (curve) get a ruler or calculate the slope of the line and use it to calculate what the OD of you sample is. Follow that down to the X axis and there is you concentration.

Use excel or some other program will be much easier. (softmax pro works well also).
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Dr.Stein
King Cobra
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Joined: Thu Jul 07, 2005 7:58 am
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From your explanation, it seems to me that the graphic would be a linear one with the formula: y = ax+b since you mentioned "ruler"? Yes I can get the "r^2" automatically with Excel or another LR analysis tool.

Now I need to know about the scale. RIA uses log-logit scale to put dots and then draw the linear graphic. What scale must I apply for ELISA?

So, could I say that the principle to determine the hormone level using ELISA is similar to RIA, which using extrapolation method after drawing the standard curve?

blcr11
Viper
Posts: 672
Joined: Fri Mar 30, 2007 4:23 am
How well it fits a straight line depends on how linear the assy is. ELISA standard curves should look similar to RIA curves. Logit-log transformations are used to linearize the curve over the range of at least 10-90% saturation.

Here is a brief overview of ELISA from Millipore Corp.
http://www.chemicon.com/resource/ANT101/a2C.asp

and a formal paper (in the public domain from PubMed) comparing different models for analysis of standard curves
http://www.pubmedcentral.nih.gov/picren ... obtype=pdf

and even an example using Prism, though I'm not sure this is very helpful