Multiple-sample probe for solid-state NMR studies of pharmaceuticals
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- 作者：Benjamin N. Nelson ; Loren J. Schieber ; Dewey H. Barich ; Joseph W. Lubach ; Thomas J. Offerdahl ; David H. Lewis ; John P. Heinrich and Eric J. Munson
- 关键词：Probe ; MAS ; High throughput ; NMR ; Solid state ; Pharmaceutics ; Analysis
- 刊名：Solid State Nuclear Magnetic Resonance
- 出版年：2006
- 出版时间：February 2006
- 年：2006
- 卷：29
- 期：1-3
- 页码：204-213
- 全文大小：463 K
文摘
Solid-state NMR spectroscopy (SSNMR) is an extremely powerful technique for the analysis of pharmaceutical dosage forms. A major limitation of SSNMR is the number of samples that can be analyzed in a given period of time. A solid-state magic-angle spinning (MAS) probe that can simultaneously acquire up to seven SSNMR spectra is being developed to increase throughput/signal-to-noise ratios. A prototype probe incorporating two MAS modules has been developed and spectra of ibuprofen and aspirin have been acquired simultaneously. This version is limited to being a two-module probe due to large amounts of space required for the tuning elements located next to the MAS modules. A new probe design incorporating coaxial transmission lines and smaller MAS modules has been constructed. This probe allows for close proximity of the MAS modules (within 3 cm), adequate proton decoupling power (>50 kHz), and the capability of remote tuning and sample changing. Spectra of hexamethylbenzene (HMB) have been acquired and show signal-to-noise ratios comparable to existing SSNMR probes. Adamantane line widths are also comparable to conventional probe technology. Decoupling powers of 70 kHz have been achieved using a MAS module suitable for 3 cm spacing between modules. Remote tuning has also been achieved with this new coaxial transmission line design. This probe design can be easily scaled to incorporate multiple MAS modules, which is a limitation of the previous design. The number of modules that can be incorporated is only limited by the number of transmission lines that will fit in a cross-sectional diameter of the bore and the axial field length of the magnet.