How can I integrate the area under a curve (from experimental data) with X & Y boundary conditions?

Hello,

How can I integrate the area under a curve (from experimental data) with X & Y boundary conditions?

My example is from chronoamperometry data (current vs time). Periodically the current will spike due to experimental conditions. I would like to integrate the area under a peak (ideally each peak) but I would like to set X & Y boundary conditions (?) so as to integrate a portion of the peak area [see attached image]. For example, in the image with green dots (my points to pick boundaries) I would like to integrate between (X1 & X2 and Y1 & Y2).

Using both trapz and cumtrapz functions, I haven’t been able to figure out how to get only my area of interest. Instead, I get the whole area under a peak [see other image with giant-"X"]. To date, the closest I’ve found to an answer appears to be from here: http://www.mathworks.com/matlabcentral/answers/122644-how-to-calculate-partial-area-under-the-curve However, I haven’t been able to figure out something that works with my data [attached].

Answer 1

[KSSV]

Use trapz....

check the link:

https://in.mathworks.com/matlabcentral/answers/154089-area-under-curve-no-function

[Saurabh Parmar]

Thank You!