JEOL GSX 400 NB FT-NMR SPECTROMETER


FT-NMR spectroscopy is used to determine the molecular structure based on the chemical environment of the magnetic nuclei like 1H, 13C, 31P, etc., even at low concentrations. This is one of the most powerful nondestructive techniques in elucidating the molecular structure of biological and chemical compounds.

 


    Description

In FT NMR spectroscopy, a strong RF pulse excites the entire range of precessional frequencies of a given nuclear species whose time response is known as free induction decay (FID) containing all the information. A Fourier transform of FID gives the NMR spectrum. This is a much faster technique compared to CW and hence it is possible to detect weak lines by signal averaging methods. This technique is used in JEOL GSX 400 NB FT-NMR spectrometer. The spectra of samples containing low abundant nuclei like 13C, 31P, etc., are thus easily obtained. Also dynamic studies are possible by relaxation measurements. Homo and hetero 1H decoupling are also possible.

JEOL GSX 400 NMR operates at 400 MHz (for proton) with a magnetic field of 9.3 Tesla. Hence a supercon magnet is used. A PDP-11/73 computer is an integral part of the instrument for the purpose of Fourier transformation and spectral manipulation. The spectrum is plotted on a HP plotter and data can be obtained on a printer. The probes available are 1H/13C combined and multinuclei probe to study the nuclei like 23Na, 27Al, 43Ca, 37Cl, 79Br, etc., except 19F, 3H and Tl. Among other things, many types of 2D spectral measurements are possible. It is possible to obtain high resolution NMR spectra of many compounds using the solids accessory employing MAS technique which otherwise are insoluble in usual solvents. Though resolution is poor, this is also useful for polymers, etc.

Sample required

5 mg for 1H and 15 mg for 13C and other nuclei. Solubility: 10 mg/ml for 1H and 50 mg/ml for 13C and others. Solvent must be specified and solubility must be checked before sending the samples in order to save the expensive deuterated solvents. Sample must be free of paramagnetic impurities.
Solvents available: CDCl3, D2O, C6D6, CD3COCD3 and DMSOd6.

    Applications

Widely used in organic chemistry, biology, medicine, pharmaceuticals, etc. for characterization of compounds.

 

First-time users : Send mail to moni@iitm.ac.in and  request for certain special instructions and guide lines in using JEOL NMR.

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