Mr. Karmakar.

Conventional IR is the cheapest and fastest approach.

Bojidarka B. Ivanova,

Thank you. Infra red technique is good.

But I already have a NMR report of the biodiesel I produced and I want to calculate out the percentage of conversion of ester from there. It would be so kind of you if you teach me how to read a NMR graph and calculate the yield of biodiesel from there.

I have never done this specifically, but I can tell you about how to read NMR. I will assume you have NMR spectra from a liquid solution and you're trying to calculate the concentration of a specific compound - your biofuel, right?

If that is what you're doing, it depends on 1) what nucleus you did NMR on and 2) what are the relaxation properties of your system. Basically, each element will give its own spectral line, but those lines will be slightly different in different compounds due to the chemical environment.

Now, suppose we're looking at some hydrocarbon in an aqueous solution. If you have NMR data on 13C, the NMR-active isotope of carbon, then any and all signal present will probably come from the hydrocarbon - unless there's other carbon-containing impurities. So you can just compare the spectral intensity to that of a reference sample of known concentration and you should be fine (well, normalising for volume and all that). If, however, you have data on 1H, then you'll see a signal both from the hydrocarbon and water. The lines will be slightly different because 1H in water is bonded to oxygen, whereas in the other compound it might be bonded to carbon. So you could still look at the relative intensity of the lines, compare with reference solutions, and work out the concentration. However the problem here is that you need to be able to tell the two lines apart. The difference in frequency won't be that big, probably, and there's a risk that it may get blurred out if the lines are very broad, that is, if the relaxation of the spins is fast. This depends on a lot of factors like what paramagnetic ions are present in your solution. I'm not really experienced with liquid solution NMR so I can't tell you the specifics of what would likely happen, but these are the basics.

Good question