Table 2.

Comparison between mass spectrometry and NMR as it applies to metabolomics research

	Mass Spectrometry	NMR
Sensitivity	≥ pM concentrations	≥ μM concentrations
Sample preparation	Minimal to extensive: deproteinization, derivatization possibly required for targeted studies	Minimal: addition of a buffered deuterium oxide solution, deproteinization optional
Sample volume	On the order of 10 μL	On the order of 100 μL or more
=Quantification	Relative concentrations are most common, absolute quantification requires internal chemical standard at known concentration for each metabolite	Absolute concentrations are standard; internal chemical standard at known concentration routinely added during sample preparation (44)
Chromatography?	Yes, either liquid or gas chromatography used prior to injection into the instrument	Not common
Sample recovered?	No: principle relies on fragmentation of molecules and physical interaction with the instrument	Yes: principle relies on nuclear spin, a fundamental property of certain nuclei, and excitation/emission of photons is nondestructive
Quality control	Inter- and intra-batch variability requires periodically testing a set of standards and correcting for changes in sensitivity over time after data collection	Not required
Global	Yes, but requires quality control and instrument expertise	Yes
Targeted: endogenous	Highly sensitive and specific	Depends on the location of the resonance peaks in the spectrum
Targeted: exogenous	Yes	Depends, and NMR-active isotopes (13C or 15N) at low natural abundance are helpful