How do you find the coordinates of a peak on an Excel graph?

[higherme]

Does anyone know how to find the maximum of a graph using excel?

so i have this graph i plotted out, and i want to find the coordinates of the peak, is there a way to do it? or do i just have to estimate?

any help would be appreciated! thanks!

 

[chemisttree]

Are you graphing from data arranged in columns?

 

[higherme]

yes... i have two columns

one column is the potential and the other one is the current

 

[chemisttree]

Highlight the column in question. Go to the pulldown menu "Data" and choose "Sort". The maxima will be the first (or last) value after sorting depending on whether you choose ascending or descending order.

 

[higherme]

hm..sorry i forgot to tell that this is a cyclic voltammogram

ya... that will work and it will give me the highest point, which is at the turning point for the potential scan (from cathode reaction to anode reaction). I want to find the peak cathodic current Ipc

 

[jim mcnamara]

The excel MAX() function will also do that kind of thing. If you need to interpolate somehow or find an inflection point I don't think there are predefined functions. You can write your own.

 

[chemisttree]

Look at http://www.chem.uic.edu/chem421/cv.PDF web site. You will notice that the maximum value is the Ipc. If that point is the turning point on your scan, you didn't scan to a high enough potential to see the peak. You still have to interpolate the baseline.