HRMAS NMR Probes
Bruker's HRMAS Probes enable high-resolution experiments on colloidal systems and semi-solids. They are ideal to record NMR spectra of samples where different physical phases coexist.
High Resolution Magic Angle Spinning (HRMAS) is an established technique for analyzing inhomogeneous and semi-solid samples. With standard solution-state NMR techniques, the spectra of such samples would suffer from broad and unresolved resonances. By spinning at the magic angle (54.7°), line broadening effects due to magnetic susceptibility differences and dipolar interactions within the sample are removed, enhancing spectral resolution, and enabling detailed analysis of the individual components within the sample. HRMAS is the ideal technique to investigate many important classes of samples, such as gels, emulsions, foodstuffs, insoluble polymers, or biological tissues.
Figure 1: Bruker’s HRMAS iProbes are equipped with a deuterium lock channel and a gradient.
Technical Details
Bruker's HRMAS probes are equipped with a gradient coil oriented along the magic angle and a deuterium lock channel. The gradient has been optimized for durability and makes a wide variety of NMR techniques accessible, including gradient enhanced solvent suppression and artefact-free homonuclear and heteronuclear 2D experiments. The tunable deuterium lock channel provides excellent frequency stability over long acquisition times.
Built upon the renowned iProbe platform, Bruker’s HRMAS NMR probes combine innovation, ease-of-use, and reliability. Bruker’s HRMAS iProbes feature integrated automatic tuning and matching, automatic magic angle adjustment, and are compatible with hardware for automatic sample changes. The HRMAS iProbe, shown in Figure 1, is available as a dual channel probe, where the high frequency channel is tunable to 1H and 19F, and the second channel covers a wide frequency range from 31P to 15N. The robust RF design makes it possible to decouple for long times, both on the X and 1H channel, allowing a high resolution in both dimensions even under heteronuclear decoupling.
Bruker’s HRMAS iProbes are available for standard bore (SB) magnets and are compatible with wide bore (WB) magnets. The probes are available for 4 mm rotors, capable of a maximum spinning speed of 15 kHz. Disposable rotor inserts are available for easy sample preparation and clean up.
Bruker's HRMAS probes support direct excitation solid-state NMR experiments. With the combination of high-resolution experiments and solid-state NMR capabilities, these probes offer an attractive solution for a wide range of research needs.
Applications
Examples for typical application of HRMAS NMR are shown below.
In medical applications, HRMAS is often applied as a nondestructive and nonperturbing method to study cancer and other pathologies by analysing tissues, blood, or cells. Due to the exceptional resolution achieved with HRMAS NMR, serial measurements of important metabolites are possible without complex extraction and purification processes.
One major field of industrial applications of HRMAS NMR is the characterization of insoluble polymers swollen in a suitable solvent. Scientific questions typically address physiochemical phenomena, like adhesion, elasticity, or degradation, and their relation to local structures such as the degree of cross-linking or the presence of chain dynamics.
Gels, emulsions, and creams are common in the manufacturing of food, cosmetics and pharmaceuticals. They can be analysed by HRMAS spectroscopy in their original form in an easy and convenient manner, without prior sample treatment.
Oligodendroglioma Cells
1H Chemical Shift (ppm)
Proton spectrum of an oligodendroglioma biopsy (central nervous system tumor). In this CPMG experiment recorded in 10 minutes, between 35 and 45 metabolites can be detected and quantified. Courtesy of Izzie J. Namer, Strasbourg University Hospital.
Osteosarcoma Cells
1H Chemical Shift (ppm)
2D 1H-13C HSQC of Osteosarcoma cells grown on [U-13C]-Glucose. The spectra was recorded on a 500 MHz HRMAS iProbe under 13C decoupling during acquisition and with an exceptionally long acquisition time (573 ms). The excellent resolution in both dimensions provides crucial information on the metabolic pathways of the cells. Sample courtesy of Izzie J. Namer, Strasbourg University Hospital.
Leggi di piùNatural Rubber
1H Chemical Shift (ppm)
2D 1H-13C spectrum of natural rubber recorded with a 600 MHz HRMAS iProbe at the temperature of 315 K. The full HSQC spectrum (not shown) was recorded in less than one hour with non-uniform sampling (25 % NUS amount). The zoom highlights the cross-linking region.
Pharmaceutical Cream with Fluocinolone Acetonide
19F Chemical Shift (ppm)
1D CMPG 19F spectrum of a pharmaceutical cream recorded on a 600 MHz HRMAS iProbe. Despite the low loading of the active pharmaceutical ingredient (Fluocinolone acetonide, 0.01 %) the signals from the two 19F nuclei can be detected in less than 30 minutes of acquisition.
CMP NMR Probes
Bruker also offers a range of CMP (Comprehensive Multiphase) probes. CMP probes share many similarities with the HRMAS probes, boasting the same high-quality construction, gradients, a lock channel, and compatibility with 4 mm rotors spinning at 15 kHz. In addition to the capabilities of HRMAS probes, Bruker’s CMP probes have been optimized with respect to power handling and thus provide an extended array of experimental techniques, including cross polarization (CP) experiments, and high-power decoupling, enabling researchers to extract even more detailed information from their samples.
For even higher performance in cross polarization and decoupling experiments, Bruker's innovative portfolio includes CPMAS (Cross Polarization Magic Angle Spinning) probes. These probes are designed specifically to optimize cross polarization efficiency and decoupling power, pushing the boundaries of NMR spectroscopy.