Advances in membrane inlet mass spectrometry (MIMS)

During the last five years there has been a tremendous expansion in thenumber of membrane inlet mass spectrometry (MIMS) techniques. Newmethods have been developed which bring detection limits for many volatileorganic compounds down to the low parts-per-trillion level and the detectionof organic compounds in organic solution has become possible. The firstexamples of the measurement of non-volatile organic compounds (boilingpoint above 300°C) have also been published. In this paper we will focus onall the new methods and tiy to give an overview of the possibilities andlimitations of these new MIMS techniques. The presentation of thetechniques has been divided into four sections: i) methods using two stagesof separation prior to the mass spectrometric detection, ii) methods usingstimulated evaporation of sample molecules from the membrane surface, iii)methods using trapping techniques for preconcentration of the samples(sorption MIMS), and iv) methods for the analysis of organic solutions(reversed phase MIMS). In addition to the new MIMS methods the reviewalso covers recent theoretical aspects including the use of flow-injectionanalysis systems and the influence of chromatographic effects in the vacuum chamber