How to find integrated peaks on NMR graphs

[paperstars]

Hi all,

I am currently self studying a chapter on Modern Analytical Chemistry. One part talks about interpreting NMR graphs and I understand the basic gist of it, however, I don't understand how to find the integrated peaks. I've looked extensively online and I now understand that you have to measure the peaks to find the ratio. BUT, how do you know where to start and stop measuring?

An example is http://www.wfu.edu/~ylwong/chem/nmr/h1/integration.html" , if you were to click on the animated flash explanation, they show how it's done, but I don't understand how they came up with where to start and stop the measurement of the peaks.

Thank you in advance!

 

[chemisttree]

If the peaks are baseline resolved, the integration begins where the deviation from the baseline into the peak begins. If peaks are not baseline resolved, a midpoint between adjacent peaks is used. It isn't exact, BTW, but it gets you close.