[TTAGGGn]

I did an experiment using IR spectroscopy on ortho-, meta-,para- xylene.

I ran each substance 4 times to get the uncertainty in the intensity. I'm suppose to normalize the spectrum of the 4 spectrums of o-xylene before finding the uncertainty in intensity.

The instructions say that there are common peaks at 1700cm-1 and at 2920cm-1. Also, it says that all the samples should have an internal standard, which are these peaks and their intensities should be the same, but the intensities are not the same. I'm guessing due to instrumental error.

So i used the highest intensity from the 4 peaks at 2920 and got the difference of the other intensities and added the difference to all the points in excel. Now all the peak intensities at 2920cm-1 are the same, but the baseline of the spectrums of the graph are not on top of one another. Is this the proper way to normalize the spectrums?

[marquis]

First, check to see if the actual peak heights are different or if the spectrum is just scxaled differently.  If it is just displayed differently, you should be able to change the scale to get comparable numbers.

The most common way to normalize is to use the ratio of the peaks.  So you might take the 1700 peak and ratio it to the 2920 peak.  Use the distance from the baseline, not the distance from the bottom of the page for your scaling. 

See if this helps and good luck!