In recent years, mass spectrometers are increasingly used as a means of detecting trace components in gases or liquids with high sensitivity. Mass spectrometers now constitute indispensable measurement and analysis equipment in fields that require ultramicro analysis.
In this type of equipment, a sample to be measured is ionized and resultant ions are analyzed in a mass spectrometric section. As a means of realizing a more sensitive microanalysis, a mass spectrometer utilizing atmospheric pressure ionization (to be hereafter referred to as APCI), particularly a liquid chromatograph mass spectrometer (to be hereafter referred to as LC/MS), is known.
In this apparatus, a mixture of substances to be measured, such as those that have been concentrated through predetermined preprocessing steps, is introduced into a liquid chromatograph (to be hereafter referred to as LC) and separated. The eluted sample and mobile phase are sent via piping such as a Teflon pipe to an atomization section, where they are heated and thereby atomized. The atomized sample and mobile phase are further turned into a molecular state and then ionized in an ionization chamber. The ionized mobile-phase molecules produce a molecular reaction with the sample molecules, and charges are transferred to sample molecules that have not yet been ionized, whereby the sample molecules are ionized gradually and almost entirely. The ionized sample molecules are delivered to a high-resolution mass spectrometric section for mass spectrometry. This apparatus is characterized in that a qualitative analysis of the measured substances can be performed based on the mass number of detected ions, and that a quantitative analysis of the measured substances can also be performed based on the intensity of detected ions.
A capillary electrophoresis/mass spectrometer (to be hereafter referred to as CE/MS) is also known, which employs capillary electrophoresis instead of LC.
Further, ion-trapping mass spectrometers are also becoming more and more common in recent years, in which an ion trap consisting of a pair of an end-cap electrode and a ring electrode is used in the mass spectrometric section of the mass spectrometer.
Examples of the ion-trapping mass spectrometer are disclosed in JP Patent Publication (Kokai) No. 8-166371 A (1996) and 8-178899 A (1996).