Membrane introduction mass spectrometry MIMS

Liquid membrane enrichment coupled to mass spectrometry. Membrane introduction mass spectrometry (MIMS) is an established method of sample... 

Levels observed were up to 500 x greater than the level (0.7 ng/L) associated with a one in a million lifetime cancer risk. Volatile DBFs, such as trichloramine, dichloromethylamine, and dichloroacetonitrile, have also been measured in pool waters using membrane introduction mass spectrometry (MIMS) [133]. Brominated DBFs from sunscreens have been reported [136], as have DBFs from the reaction of chlorine with parabens used in lotions, cosmetics, and sunscreens [117]. 

In an attempt to overcome the significant difficulties that the presence of water vapor poses to the analysis of very volatile compounds, purge-and-membrane extraction techniques have been developed that largely prevent the introduction of water into the analytical system. Typical implementations of this form of sample introduction have been called by its developers membrane extraction with a sorbent interface (MESI),97 or membrane introduction mass spectrometry (MIMS).98 " They are based on a silicone hollow-fiber membrane that is inserted into the sample to be monitored, and the passing of a certain volume of inert gas through the membrane. Volatile compounds permeate the membrane and are swept to the adsorbent trap from which they are desorbed into the GC. This method of sample introduction is particularly suited for field and process monitoring and for dirty samples, since it prevents any nonvolatile compounds from entering the analytical system.100... 

The use of membrane introduction mass spectrometry (MIMS) was first reported in 1963 by Hoch and Kok for measuring oxygen and carbon dioxide in the kinetic studies of photosynthesis [46], The membrane module used in this work was a flat membrane fitted on the tip of a probe and was operated in the MIS mode. The permeated anaytes were drawn by the vacuum in the MS through a long transfer line. Similar devices were later used for the analysis of organic compounds in blood [47], Memory effects and poor reproducibility plagued these earlier systems. In 1974, the use of hollow-fiber membranes in MIMS was reported, which was also operated in the MIS mode [48], Lower detection limits were achieved thanks to the larger surface area provided by hollow fibers. However, memory effects caused by analyte condensation on the wall of the vacuum transfer line remained a problem. 

Another MS technique used in connection to pyrolysis is MIMS (membrane introduction mass spectrometry). MIMS is in fact a special inlet for the mass spectrometer, where a membrane (usually silicone, non-polar) lets only certain molecule types enter the Ionization chamber of the MS. This allows, for example, direct analysis of certain volatile organic compounds from air. The system makes possible the coupling of atmospheric pyrolysis to a mass spectrometer [61a] allowing direct sampling of the pyrolysate. Other parts of the mass spectrometer do not need to be changed when using MIMS. 

The need for maximum sample throughput and minimal human interaction within analytical procedures has provided considerable impetus to the development of integrated systems. SPE-LC in-tube SPME followed by ultraviolet (UV) or MS detection and membrane introduction mass spectrometry (MIMS) have both been used to this end. Submersible MIMS systems capable of extended underwater deployment down to 200 m and with a mass range of up to 200 amu have recently come onto the market. Elow injection coupled with MIMS allows fast, near-real-time determination of, for example, phenols in water. Derivatization of the phenols with acetic anhydride can be used to enhance both the selectivity and sensitivity of this method. Other online derivatization procedures are under development with a view to increasing the scope for rapid determination of highly polar compounds that have previously proved difficult to analyze. Large volume injection techniques and developments in enzyme-linked immunosorbent assay (ELISA) technologies... 

Membrane introduction mass spectrometry (MIMS) is a state-of-the-art technique that combines the quick separation of volatile analytes from complex matrices using selective membranes with the precision offered by mass spectrometry (MS) on chemical identification and quantification [1], Compared with gas or liquid chromatography (GC or LC) traditionally used in front of MS, the membrane separation technique has the advantages of being both simple, which minimizes sample preparation, and rapid, which makes real-time monitoring possible [2], The use of a mass spectrometer as the detector also makes MIMS less subject to analytical interference, a frequent limitation of non-MS-based techniques such as calorimetry [3,4],... 

Epichlorohydrin is extracted from water by SPE on a Chromabond HR-P column. Purther analysis is by GC [39]. Johnson et al. [45] monitored online epichlorohydrin in water with liquid membrane introduction mass spectrometry (MIMS). 

Nonporous polymeric membranes have been incorporated as sample inlets in mass spectrometry (MS) for the direct sampling of volatile and semivolatile organic compounds (VOCs and SVOCs). The technique of membrane inlet (introduction) mass spectrometry (MIMS) has achieved tremendous success in the last two decades in terms of instrumentation and applications. Figure 4.1 depicts the experimental setup of (i) in-sample membrane MIMS and (ii) direct insertion (near the ion source in MS) membrane MIMS. 

A consequence of MESI application is the membrane introduction mass spectrometry system (MIMS), which allows selective extraction of VOCs and direct MS analysis without chromatographic separation. The gaseous substances permeate through the highly hydrophobic membrane and are introduced directly to a mass spectrometer [115-118]. 

MIMS membrane inlet (introduction) mass spectrometry... 

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