Varian Associates, Inc.

Ronald L Haner

Christopher Cameron Kellogg

David W Duff

A three-piece NMR detection cell comprises an inlet tube having a conically, tapered outlet nozzle, leading to an analysis tube, in turn leading to an outlet tube having a conically tapered inlet nozzle. The inlet and outlet tubes are inserted into the analysis tube at a distance from their inserted ends and sealed in a manner appropriate to their composition. When the detection cell is used in a coupled HPLC-NMR apparatus, increased NMR sensitivity and improved lineshape are obtained at low injection volumes while maintaining a low level of chromatographic band broadening and a high level of magnetic field homogeneity.

Flow tube for NMR probe

A sample delivery system for a flow-through NMR analysis is provided, which utilizes pressurized gas as a means for conveying a sample into and out of an NMR spectrometer. Two sources of gas pressure, a forward pressure and back pressure, oppose the sample within the tubing of the sample delivery system and the tubing of the flow-through system which are operatively coupled together. Conveyance of the sample in any direction within the tubing is achieved by adjusting the pressure differential. Precise positioning of the sample in the magnetic field center and complete removal of the sample from the NMR spectrometer when analysis is complete are achieved by using a signal processor which receives signals from the NMR detector or other detectors positioned along the length of the tubing. These signals provide an indication of the position of the sample in the tubing. The signal processor uses this information to adjust the forward and back pressure, thereby achieving the desired positioning of the sample.

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San Francisco, CA, United States of America

Ronald L Haner