Polarization transfer methods for quantitative analysis of flowing mixtures with benchtop C NMR spectroscopy.

Benchtop NMR spectroscopy is attractive for process monitoring; however, there are still drawbacks that often hamper its use, namely, the comparatively low spectral resolution in H NMR, as well as the low signal intensities and problems with the premagnetization of flowing samples in C NMR. We show here that all these problems can be overcome by using H-C polarization transfer methods. Two ternary test mixtures (one with overlapping peaks in the H NMR spectrum and one with well-separated peaks, which was used as a reference) were studied with a 1 T benchtop NMR spectrometer using the polarization transfer sequence PENDANT (polarization enhancement that is nurtured during attached nucleus testing).