Development of a quadrupole mass spectrometer using the second stable zone in Mathieu’s stability diagram

A quadrupole mass spectrometer (QMS) utilizing the second stable zone in Mathieu’s stability diagram was developed. The system performance was experimentally compared with the conventional QMS using the first stable zone. The peak shapes obtained were sharper and the tail components arising from adjacent peaks were less than those of the conventional QMS, although the analyzable range was limited to lower mass and the attenuation in sensitivity was about 1/50. This improved QMS is usable in detecting very small peaks adjoining large ones.