FAQ

qNMR acquisition literature processing

qNMR stands for quantitative NMR. During setup of the experiments, extra care is taken to choose the acquisition parameters in such a way that quantitation of the results is possible. Referencing can be done using both internal and external standards as well as using an electronic reference signal generated by the spectrometer.

Some references

Pauli, G. F., qNMR - A versatile concept for the validation of natural product reference compounds. Phytochem. Anal. 2001, 12 (1), 28-42. DOI: 10.1002/1099-1565(200101/02)12:1<28::AID-PCA549>3.0.CO;2-D

Malz, F.; Jancke, H., Validation of quantitative NMR. J. Pharm. Biomed. Anal. 2005, 38 (5), 813-823. DOI: 10.1016/j.jpba.2005.01.043

Bharti, S. K.; Roy, R., Quantitative ¹H NMR spectroscopy. TrAC, Trends Anal. Chem. 2012, 35, 5-26. DOI: 10.1016/j.trac.2012.02.007

Weber, M.;  Hellriegel, C.;  Rueck, A.;  Wuethrich, J.;  Jenks, P.; Obkircher, M., Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as ³¹P qNMR standards. Anal. Bioanal. Chem. 2015, 407 (11), 3115-3123. DOI: 10.1007/s00216-014-8306-6

Muhamadejev, R.;  Melngaile, R.;  Paegle, P.;  Zibarte, I.;  Petrova, M.;  Jaudzems, K.; Veliks, J., Residual Solvent Signal of CDCl₃ as a qNMR Internal Standard for Application in Organic Chemistry Laboratory. J. Org. Chem. 2021, 86 (5), 3890-3896. doi: 10.1021/acs.joc.0c02744

Jaki, B. U.;  Bzhelyansky, A.; Pauli, G. F., Quantitative NMR (qNMR) for pharmaceutical analysis: The pioneering work of George Hanna at the US FDA. Magn. Reson. Chem. 2021, 59 (1), 7-15. DOI: 10.1002/mrc.5099

Nishizaki, Y.;  Lankin, D. C.;  Chen, S.-N.; Pauli, G. F., Accurate and Precise External Calibration Enhances the Versatility of Quantitative NMR (qNMR). Anal. Chem. 2021, 93 (5), 2733-2741. DOI: 10.1021/acs.analchem.0c02967

qNMR guideline

Sigma Aldrich brochure on qNMR

fluorine 19F J coupling constants

Some references

Emsley, J. W.;  Phillips, L.; Wray, V., Flourine coupling constants. Prog. Nucl. Magn. Reson. Spectrosc. 1976, 10 (2), 83-752. DOI: 10.1016/S0079-6565(76)80005-2

fluorine 19F reference processing

Fluorine NMR spectra are quite often misreferenced. The paper in the references section is a must read if you want to avoid these mistakes.

Some References

Rosenau, C. P.;  Jelier, B. J.;  Gossert, A. D.; Togni, A., Exposing the Origins of Irreproducibility in Fluorine NMR Spectroscopy. Angew. Chem., Int. Ed. 2018, 57 (30), 9528-9533. DOI: 10.1002/anie.201802620

processing solvent residuals

The following papers should be on your desk if you quickly want to find out what these extra peaks are in your spectra.

Some references

Gottlieb, H. E.;  Kotlyar, V.; Nudelman, A., NMR Chemical Shifts of Common Laboratory Solvents as Trace Impurities. The Journal of Organic Chemistry 1997, 62 (21), 7512-7515. DOI: 10.1021/jo971176v

Fulmer, G. R.;  Miller, A. J. M.;  Sherden, N. H.;  Gottlieb, H. E.;  Nudelman, A.;  Stoltz, B. M.;  Bercaw, J. E.; Goldberg, K. I., NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist. Organometallics 2010, 29 (9), 2176-2179. DOI: 10.1021/om100106e

Babij, N. R.;  McCusker, E. O.;  Whiteker, G. T.;  Canturk, B.;  Choy, N.;  Creemer, L. C.;  Amicis, C. V. D.;  Hewlett, N. M.;  Johnson, P. L.;  Knobelsdorf, J. A.;  Li, F.;  Lorsbach, B. A.;  Nugent, B. M.;  Ryan, S. J.;  Smith, M. R.; Yang, Q., NMR Chemical Shifts of Trace Impurities: Industrially Preferred Solvents Used in Process and Green Chemistry. Org. Process Res. Dev. 2016, 20 (3), 661-667. DOI: 10.1021/acs.oprd.5b00417