how to calculate ic 50?

Hi
to a non initiate, your question is about as difficult to understand as quantum physics. Perhaps there are forums somewhere for this kind of specialized stuff ?

Hi,

Plotting the data you give above, I get an equation of:

y = 1.2317x + 85.214

with

Rē = 0.9016

though, since I am not an expert in whatever chemical analysis you are performing, I have no idea what it might mean to have, as you put it, "a negative ic50 value". This is your field - shouldn't that be something you know? Or, if not, something better suited to a different forum?

Regards

But you haven't taken the time to explain what 'ic50' is, nor how it fits in with the data you have given.

Reminder: this is an Excel forum. Please explain how your question re 'ic50' is Excel-related and then perhaps we can help.

Regards

And, based on your knowledge, would you expect the relationship between % of Inhibition and Concentration to be linear? Exponential? Polynomial?

The reason I ask is that, based on the linear interpolation I carried out on your dataset, using Excel's in-built TREND function predicts a Concentration of -508.641 at 50% Inhibition.

Despite my lack of expertise, I very much doubt this is correct. Perhaps you should experiment with an exponential relationship? Or, as you say, plot the logarithms of each variable against each other?

Again, though, this is not my area of expertise, so perhaps, when you've determined the type of relationship involved, you can come back and ask for advice on how to interpret your data based on whatever new information you have.

Best of luck and regards.

I'm afraid that's a question more appropriate to a chemistry/mathematics forum than to an Excel one. Or perhaps you could do some reading (either online or maybe you have a local library)?

Regards

samrina, I think what everyone who has replied here, is trying to say, is that we have NO idea what ic50 IS, let alone how it would be calculated or how to tell if it is right or wrong.

Remember, you know what you are talking about, we dont