Abstract: An ion trap mass spectrometer uses electrospray ionization to introduce multiply-charged positive ions in an axial direction into a quadrupole ion trap and glow discharge ionization to introduce singly-charged negative ions in a radial direction into the ion trap. Methods of controlling ion-to-ion charge transfer reactions include applying dipolar DC voltage across endcap electrodes to allow partial charge state neutralization reactions to occur between the positive and negative ions and then suspending further charge state neutralization reactions. The remaining ions can be further processed and transformed and a mass spectrum created by scanning a quadrupolar RF field.

Abstract: The sealing apparatus of the present invention is a sample cuvette cap having a hole for inserting the nozzle of an auto-sampler therethrough. Located within the lumen of the hole is a small detent ball that can be positioned to block the lumen. The detent ball, which can be spring-operated or gravity-operated, blocks the fluid flow in the hole in its normal, closed position. When the auto-sampler nozzle hits the ball, the ball becomes deflected to one side into a recess, due to a difference in the nozzle axis relative to the center of the ball. By the dislocating the detent ball, the nozzle can be inserted into the cuvette smoothly as the air goes in and out through the space around the nozzle. This allows the pressure in the cuvette to be kept constant. After the nozzle is removed, the ball returns to its original position by gravity or by the force of a spring, resealing the cuvette. All of the parts for the sealing apparatus are solid parts which can be easily cleaned and reused.

Abstract: In a magnetic resonance imaging system, object movement along an axis associated with readout magnetic gradient pulses is detected, quantized and compensated for in reconstructing an image slice. Phase-encoding magnetic gradient pulses in the sequence are arranged so that low-order phase-encoding pulses are distributed substantially uniformly during scanning time. In an N-slice acquisition, object movement is determined y arranging each of the N sets of phase-encoding gradient pulses comprising a multi-slice sequence such that at each scan time, at least one of the N sets contains a low-order phase-encoding gradient pulse. During data acquisition, echoes returned from low-order phase-encoding gradient pulses have sufficient signal-to-noise ratios to identify object position along the readout axis. Identification of object movement from one slice may be valid for other slices relatively adjacent physically in the object, so that all N slices are movement corrected during image reconstruction.