Abstract: An NMR flow cell assembly comprises: a flow cell for holding a sample; inlet and outlet sample tubing providing fluidic access to the flow cell; and a pair of connectors connecting the inlet and outlet sample tubing to the flow cell. Each connector is secured to the flow cell by an adhesive region. The adhesive region is separated from the interior of the flow cell by an annular adhesive-separation barrier extending between the flow cell and said each of the pair of connectors. The barrier may be formed by an O-ring, or ridges formed in the flow cell wall. In another embodiment, the flow cell and connector have matching helical threads, and a sealing barrier such an O-ring or ferrule is placed along a transverse end face of the flow cell, such that the sealing force on the flow cell is longitudinal and/or outward.

Abstract: Increased distributed capacitance for an NMR resonant probe coil is obtained by a surrounding conducting surface which is congruent to and spaced from the major portion of the RF current density distribution on the surface of the inductive component of the resonator. This surface is interrupted with one or more gaps to avoid or control circulating currents on the conducting surface which reflect the circulating currents of the inductive component.

Abstract: Increased distributed capacitance for an NMR resonant probe coil is obtained by a surrounding conducting surface which is congruent to and spaced from the major portion of the RF current density distribution on the surface of the inductive component of the resonator. This surface is interrupted with one or more gaps to avoid or control circulating currents on the conducting surface which reflect the circulating currents of the inductive component.

Abstract: Increased distributed capacitance for an NMR resonant probe coil is obtained by a surrounding conducting surface which is congruent to and spaced from the major portion of the RF current density distribution on the surface of the inductive component of the resonator. This surface is interrupted with one or more gaps to avoid or control circulating currents on the conducting surface which reflect the circulating currents of the inductive component.

Abstract: A flow-through NMR probe having an NMR flow tube that is easily inserted or removed is provided together with a method for exchanging the flow tube assembly in the probe. The NMR flow tube is positioned through a lower and upper insulator in a flow-through NMR probe by the use of a guide tube. The upper and lower insulators preferably comprise a pulsed field gradient housing. The guide tube leads from the base of the probe to the lower insulator. The NMR flow tube with attached inlet tubing is inserted into the probe through the guide tube and aligned along the central axis of the probe through upper and lower insulators. The flow tube is aligned using upper and lower insulator rings positioned in the upper and lower insulators. The ease of insertion or exchange of the flow tube in the probe is further promoted by the guide tube having a smoothly tapered inner surface.

Abstract: 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.

Abstract: 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.