Advances in membrane inlet mass spectrometry (MIMS)

During the last five years there has been a tremendous expansion in the
number of membrane inlet mass spectrometry (MIMS) techniques. New
methods have been developed which bring detection limits for many volatile
organic compounds down to the low parts-per-trillion level and the detection
of organic compounds in organic solution has become possible. The first
examples of the measurement of non-volatile organic compounds (boiling
point above 300°C) have also been published. In this paper we will focus on
all the new methods and tiy to give an overview of the possibilities and
limitations of these new MIMS techniques. The presentation of the
techniques has been divided into four sections: i) methods using two stages
of separation prior to the mass spectrometric detection, ii) methods using
stimulated 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 review
also covers recent theoretical aspects including the use of flow-injectionanalysis systems and the influence of chromatographic effects in the vacuum chamber.