Patent ID: 7199581
Filing Date: 2007-04-03
Classification: G01N

Abstract:
1. A nuclear magnetic resonance method configured for use in a magnetic resonance measuring system having at lest least one magnetic field in order to determine the mass of non-continuous and discrete samples in a production line, the nuclear magnetic resonance method providing compensation of drift in the nuclear magnetic resonance measuring system, comprising: a) applying a first magnetic field in a first direction in an interrogation zone in order to create a net magnetisation within a first sample having unknown mass and at least one other non-continuous and discrete second sample of known mass located within the interrogation zone; b) applying an alternating magnetic field in a second direction in the interrogation zone in order to temporarily change the net magnetisation of the first sample and the second sample located within the interrogation zone; c) monitoring energy emitted by the first sample while the first sample is in the interrogation zone as the net magnetisation of the first sample returns to its original state and generating a first output signal having a characteristic which is proportional to the energy emitted by the first sample; d) monitoring energy emitted by the second sample within the interrogation zone as the net magnetization of the second sample returns to its original state and generating a second output signal having a characteristic which is proportional to the energy emitted by the second sample and which corresponds to the characteristic of the first output signal; e) comparing the first output signal characteristic with corresponding characteristics of the first output signal and the second output signal in order to determine the unknown mass of the first sample; f) maintaining a constant stability third sample within an access of the interrogation zone during steps a) through d); g) at least periodically performing measurements of the mass of the constant stability third sample by applying the first magnetic field in the first direction in the interrogation zone in order to create a net magnetisation within the constant stability third sample located within the interrogation zone, applying the alternating magnetic field in the second direction in the interrogation zone in order to temporarily change the net magnetization of the constant stability third sample located within the interrogation zone, monitoring energy emitted by the constant stability third sample as the net magnetization of the constant stability third sample returns to its original state and generating a third output signal having a characteristic which is proportional to the energy emitted by the constant stability third sample; h) comparing the periodically performed constant stability third sample mass measurements in order to determine, over time, an amount of drift in the magnetic resonance measuring system; and i) when appropriate adjusting the first sample mass and the second sample mass measurement values in order to compensate for the amount of drift in the magnetic resonance measuring system.