I am looking for a more in-depth comparison in between these techniques with regards to the general analysis of compounds, if anyone could help?
Off the top of my head, pros of the qNMR would be the detailed structural information provided, the fact that it is non-destructive and less expensive when compared to the MS and that it requires a single standard to quantify many components.
Cons of the qNMR would be the poor sensitivity and the fact it can only be applicable to NMR active compounds...
I agree with previous contributor
NMR advantages:
-no need of prior working out of molar responses simply because it's the same value for ALL protons
-a wide response window that contains well resolved peaks
-quick set up and rapid answer
NMR minus points:
-cost of instrument
- larger amounts of material needed ( from 0,5 mg)
In my experience
-determinations of molar ratios in mixtures of compounds - as diverse as carbohydrates, peptides and various other 'impurities'
-absolute quantitations (simply after having added known amount of internal standard)
are both relatively straightforward
-results of quantitation by NMR of 'in house prepared model sample' gave same results as gravimetry - within 1 %
For the other methods, the plus and minus will depend on sample type and content
and the particular type of Mass Spec. , UV Vis or LC instrument you have at hand
eg: LC is not as universal - may require several different detectors in cascade etc...
Dear Andreea,
on BIG advantage you have not mentioned is that you do not need reference compounds or pure samples if the machine is calibrated once with a arbitrary sample. The sensitivity of a NMR machine is universal (if the pulse is known and determined). This holds (in our experience) true if a accuracy of 5% is suited for you.
Alfred
I agree with previous contributor
NMR advantages:
-no need of prior working out of molar responses simply because it's the same value for ALL protons
-a wide response window that contains well resolved peaks
-quick set up and rapid answer
NMR minus points:
-cost of instrument
- larger amounts of material needed ( from 0,5 mg)
In my experience
-determinations of molar ratios in mixtures of compounds - as diverse as carbohydrates, peptides and various other 'impurities'
-absolute quantitations (simply after having added known amount of internal standard)
are both relatively straightforward
-results of quantitation by NMR of 'in house prepared model sample' gave same results as gravimetry - within 1 %
For the other methods, the plus and minus will depend on sample type and content
and the particular type of Mass Spec. , UV Vis or LC instrument you have at hand
eg: LC is not as universal - may require several different detectors in cascade etc...
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