International Business Machines Corporation

Carl R Valentino

Vincent N Kahwaty

Donald Clifford Hofer

Einar S Mathisen

Paul A Schumann, Jr

Frank A Litz

An NMR (nuclear magnetic resonance) spectrometer has a permanent magnet provided with a field coil. A lock system cyclically pulses a deuterium lock sample to produce a FID (free induction decay) signal that is analyzed by measuring the time interval during which the FID signal crosses the zero axis a predetermined number of times. The measured interval is compared to a predetermined interval or set point, and the current through the field coil is adjusted in the direction tending to correct the field strength so as to maintain the measured interval equal to the preset interval. Such measurement, comparison and adjustment are done several times each second. When the sample is removed, the lock system retains the last field setting achieved with the sample.

NMR field frequency lock system

A method is described for the quantitative analysis of a solution in which the solvent produces a nuclear magnetic resonant (NMR) spectral peak that dominates the system. A first spectrum containing the peak is made by operation of a nuclear magnetic resonant spectrometer at a first gain setting. The NMR apparatus is a pulse-modulated, Fourier-transform type spectrometer. A second spectrum is produced in which a 180.degree. pulse is applied to invert the spectral component magnetization followed after a period of time by a 90.degree. pulse. The period of time is sufficient to allow the solvent or component producing the unwanted peak to relax from the inverted state to a point where there is minimum magnetization along the longitudinal axis. At this point, in many solutions the other components have completely relaxed so that the 90.degree. pulse produces a free induction decay signal which, after undergoing the Fourier-transformation, yields a spectrum that does not include any significant peak due to the solvent. Thereafter, the quantitative analysis is performed by measuring the areas under the respective component peaks and simultaneously solving a series of equations in which the weight of the various components is proportional to the respective areas under the peaks and to the gain settings of the spectrometer.

Quantitative analysis of nuclear magnetic resonance spectra having

An automatic handling system selectively conveys test samples to a test probe for analysis by an instrument. The test samples are contained in sample containers. A magazine contains sampler holders each of which contains sample containers. A transport system conveys the magazine so that the holders successively pass through an extraction station from where the holders can be taken from the magazine and placed back therein. The holders upon extraction are then conveyed past a test probe so that individual samples can be selectively presented to the probe.

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Hopewell Junction, NY, United States of America

Carl R Valentino