Optimization of homonuclear 2D NMR for fast quantitative analysis: application to tropine-nortropine mixtures.
Quantitative analysis by (1)H NMR is often hampered by heavily overlapping signals that may occur for complex mixtures, especially those containing similar compounds. Bidimensional homonuclear NMR spectroscopy can overcome this difficulty. A thorough review of acquisition and post-processing parameters was carried out to obtain accurate and precise, quantitative 2D J-resolved and DQF-COSY spectra in a much reduced time, thus limiting the spectrometer instabilities in the course of time. The number of t(1) increments was reduced as much as possible, and standard deviation was improved by optimization of spectral width, number of transients, phase cycling and apodization function. Localized polynomial baseline corrections were applied to the relevant chemical shift areas. Our method was applied to tropine-nortropine mixtures. Quantitative J-resolved spectra were obtained in less than 3 min and quantitative DQF-COSY spectra in 12 min, with an accuracy of 3% for J-spectroscopy and 2% for DQF-COSY, and a standard deviation smaller than 1%.
Giraudeau
Patrick
P
Laboratoire d'Analyse Isotopique et Electrochimique de Métabolismes, UMR CNRS 6006, Université de Nantes, Faculté des Sciences, F-44322 Nantes Cedex 03, France. patrick.giraudeau@univ-nantes.fr
Guignard
Nadia
N
Hillion
Emilie
E
Baguet
Evelyne
E
Akoka
Serge
S
D045424:Complex Mixtures / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015394:Molecular Structure; D013696:Temperature; D013997:Time Factors; D014326:Tropanes / Q000032:analysis* / Q000737:chemistry; D014867:Water / Q000737:chemistry
D045424:Complex Mixtures; D014326:Tropanes; D014867:Water; C005864:tropine