Progression Inc (formerly Auburn and then Oxford Instruments) have been placing low field time-domain (TD) NMR spectrometers in the field for 15+ years. The main arena for their on-line analysis is polyolefins though they are now trying to extend their application base into coal and mining. They have 120+ systems in the field which is a lot considering that most NMR spectroscopists aren’t even aware of their existence. They have recently publised two application notes on TD-NMR applied to polypropylene resins and polyethylene resins. The bottom line is that most TD-NMR spectrometers can perform the analysis, however, the sample grabbing, pre-conditioning and delivery to the NMR are key.
It would be interesting to take detailed liquid-state 1H and 13C analyses, with complimentary solid-state 13C CP- and SP-MAS relaxation data in order to map the correlation between TD-NMR FID and CPMG profiles and the detailed chemistry of the samples.