Abstract
The construction and performances of a dual EI/CI ion source designed for the Shimadzu GCMS-9000 are described. Some design considerations on the construction of the combined gaschromatograph-EI/CI mass spectrometer are also described. Among various operating parameters for chemical ionization, ion source temperature has noticeable effects on CI spectra. Several measurements on temperature effect were carried out. As CI spectra are generally simpler and have greater abundance of quasi molecular ion than EI spectra, it is favourable to detect trace amount of sample with mass frag-mentography technique. Typical example which will show the minimum detectable amount is also shown. It is possible with this source to measure various mass spectra such as EI, CI, CE and combined CE/CI spectra of the same sample. Examples of such spectra data are presented.
