title: Hartmann-Hahn 2D-map to optimize the RAMP-CPMAS NMR experiment for pharmaceutical materials.
abstract: Cross polarization-magic angle spinning (CPMAS) is the most used experiment for solid-state NMR measurements in the pharmaceutical industry, with the well-known variant RAMP-CPMAS its dominant implementation. The experimental work presented in this contribution focuses on the entangled effects of the main parameters of such an experiment. The shape of the RAMP-CP pulse has been considered as well as the contact time duration, and a particular attention also has been devoted to the radio-frequency (RF) field inhomogeneity. (13)C CPMAS NMR spectra have been recorded with a systematic variation of (13)C and (1)H constant radiofrequency field pair values and represented as a Hartmann-Hahn matching two-dimensional map. Such a map yields a rational overview of the intricate optimal conditions necessary to achieve an efficient CP magnetization transfer. The map also highlights the effects of sweeping the RF by the RAMP-CP pulse on the number of Hartmann-Hahn matches crossed and how RF field inhomogeneity helps in increasing the CP efficiency by using a larger fraction of the sample. In the light of the results, strategies for optimal RAMP-CPMAS measurements are suggested, which lead to a much higher efficiency than constant amplitude CP experiment.
authors.affiliation: Tectospin, Institut Lavoisier de Versailles, Université de Versailles Saint-Quentin-en-Yvelines, Versailles Cedex, France; NMRTEC Bd Sebastien Brand, Illkirch-Graffenstaden, France. kazusait@chimie.uvsq.fr.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Suzuki
authors.forename: Charlotte
authors.initials: C
authors.lastname: Martineau
authors.forename: Gerhard
authors.initials: G
authors.lastname: Fink
authors.forename: Stefan
authors.initials: S
authors.lastname: Steuernagel
authors.forename: Francis
authors.initials: F
authors.lastname: Taulelle
mesh_terms: D000218:Adamantane / Q000737:chemistry / Q000302:isolation & purification*; D003627:Data Interpretation, Statistical; D005998:Glycine / Q000737:chemistry / Q000302:isolation & purification*; D007052:Ibuprofen / Q000737:chemistry / Q000302:isolation & purification*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011522:Protons; D011846:Radio Waves; D059629:Signal-To-Noise Ratio
chemical_list: D011522:Protons; D000218:Adamantane; D005998:Glycine; D007052:Ibuprofen