An investigation of small commercial quadrupole mass spectrometers

This paper presents a detailed investigation of the characteristics of the small quadrupole mass spectrometers used extensively for partial pressure measurement. Interest has centered upon determining (a) the upper and lower limits to the useful pressure range, (b) the accuracy of measurement, and (c) the long‐term stability of the characteristics. Measurements have been made to cover the whole range of the instruments. The general conclusions are that great care must be taken in operating and interpreting measurements if anything more than qualitative results are required. It is also noted that there are significant differences between the performance of instruments with similar sets of published specifications. The suggestion is made in the paper that an agreed practice be adopted for defining a precise format for presenting performance characteristics.