Qualitative Analyses of Mixtures: I have primarily done mass spectrometry during my career, but also utilize NMR data in conjunction with mass spectrometry data to identify components. Even relatively complex mixtures can be characterized by 1D and 2D NMR data utilizing complimentary information obtained by either LC-MS or GC-MS analyses.
Low Field versus High Field NMR:
Most of my work was peformed with expensive high field (400-1000 MHz) NMR’s requiriing cryrogens. However, the recent introduction of many new low field instruments (40-125 MHz) with permanent magnets should benefit laboratories which do not have the budget or resources to support the high-field NMR’s.
Here are some leading references on low field instruments:
Bruker for Forensic Applications
Q-Magnetic 125 MHz Instrument
2020 Review Article
Quantitative Analyses of Mixtures: In addition, a mixture sample can be used to generate a secondary standard for GC, LC, GC-MS, LC-MS, etc. using quantitative NMR with an internal standard.
Quantitative NMR Link 1
Quantitative NMR Link 2
Laura Adduci shared with me a very useful NMR presentation of tips, tricks, and techniques. Laura currently works in our NMR laboratory at Eastman Chemical Co., but prepared the presentation while attending UNC-Chapel Hill.
NMR at UNC: Tips, Tricks, and Techniques
We also utilize both carbon and proton NMR for quantitative analyses. It is a very powerful approach because standards are not required to calibrate the instrument response. All that is required is that the component or components of interest be correctly identified. I have included three links below that I have found very useful for quantitative NMR analyses:
Practical Guide for Quantitative 1D NMR Integration
A "Little" Mass Spec and Sailing 
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