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nikolajeremic
USA
3 Posts |
 Posted - 11/26/2013 : 06:07:10 AM
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Origin Ver. and Service Release (Select Help-->About Origin): OriginPro 9.0
Operating System: Win7 64-bit
Hello everybody, I am new to Origin, so I would be really grateful if somebody could explain how to calculate IC50 value from DPPH test in Origin. When I perform nonlinear sigmoidal fit, I get some strange numbers, so I don`t know what I`m doing wrong.
Please, if somebody knows how to do this, help me as I`m kinda stuck at this point.
Thank you!
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greg
USA
1378 Posts |
Posted - 11/26/2013 : 09:19:52 AM
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| Using the DoseResp or Logistic function will calculate EC50/IC50 values. |
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nikolajeremic
USA
3 Posts |
Posted - 01/14/2014 : 5:03:59 PM
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Thanks for the reply. Could you(or anybody else) please further explain how to do that. Here is what I do, so just tell me if I`m doing it right: x-axis is log values of concentration, y is Inhibition(%) than I plot that, and perform DoseResp analysis(just by opening the dialog, selecting DoseResp under function and than I click fit). I have seen a video on youtube on which they set A1 value as 0, and A2 value as 100. Do I need to do that?
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nikolajeremic
USA
3 Posts |
Posted - 01/14/2014 : 5:16:00 PM
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| Sorry, I forgot to ask, also how do I calculate standard deviation for IC50 given the SE?? |
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greg
USA
1378 Posts |
Posted - 01/15/2014 : 08:54:04 AM
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If your Inhibition is indeed % then it is reasonable to set A1 and A2 as 0 and 100 and set both to fixed. You do this on the Parameters tab.
The EC50 is just a point on the curve which does have a Standard Error, but I'm not sure there is such a thing as Standard Deviation for that point. Maybe someone else knows?
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IC50 value from antioxidant assay