With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years, during which a number of miniature mass spectrometers employing different techniques have been developed. Small-in-size, working at relatively high pressure region and capable of performing tandem mass spectrometry, ion trap is the most widely used mass analyzer in miniature mass spectrometer systems. The recent development of miniature ion trap mass spectrometer systems in the last ten years was reviewed in this paper. These instruments adopt different atmospheric pressure interfaces(APIs), which are membrane inlets(MIs), discontinuous atmospheric pressure interface(DAPI)and continuous atmospheric pressure interface(CAPI). This review emphasizes on the mini mass spectrometry(MS) system that can be handheld by one person, but not the field-able ones that are too large to be hand-portable.
