ABSTRACT
As technology advanced, with the development of flexible fused silica capillary GC columns and quadrupole mass analysers, one of the instrument manufacturers, Hewlett Packard, believed it was worth developing a bench-top mass spectrometer as a dedicated and fully automated GC detector. The advent of fused silica capillary GC columns instead of packed columns meant that the columns were flexible and the optimal flow rate of the mobile phase, helium, was 1-2ml/min instead of 2030ml/min. The reduction in flow rate meant that a sophisticated interface was no longer required to interface the GC to the ionisation chamber (source) of the mass spectrometer, as conventional turbo, diffusion and/or rotary pumps could maintain the reduced pressure of between 10-3 and 10-5
torr(10-1-10-3Pa) that is required for efficient ionisation and operation of the mass spectrometer. The GC column in this instrument came out of the side of the GC, along a heated tube, straight into the ion source of the mass spectrometer. This instrument, launched in 1982, was called the HP 5970 mass selective detector (MSD). This, and other instruments based on similar technology, proved to be highly successful in bioanalysis. It is especially suited to automated quantitative analysis. It is relatively cheap, easy to use and reliable, hence during the 1980s the number of GC-MS methods developed and reported in the literature grew immensely. Since 1982, GC-MS systems based on this technology have developed so that most of the maufacturers of mass spectrometers produce such a
system. Hewlett Packard now produces the HP 5973, which has ceramic quadrupoles that are so small that the analyser fits inside the oven of the GC.
