Membrane inlet mass spectrometry, MIMS

Harmett, H. E., and Seitzinger, S. P. (2003). High-resolution nitrogen gas profiles in sediment porewaters using a new probe for membrane-inlet mass spectrometry (MIMS). Mar. Chem. 83, 23-30. 

The newest approach to measuring denitrification uses a mass spectrometer that can rapidly measure the N2/Ar ratio in water using membrane inlet mass spectrometry (MIMS, Kana et al., 1994, 1998). In this approach, sediment cores are incubated under continuous flow conditions. The N2/Ar ratio is then measured at the inlet and outlet of the core over time. Advantages of the technique are the short incubation times needed (usually less than 12 h), and the high throughput and small sample size ( 5 ml) of MIMS analysis. 

Although GC-methods are widely used, they are time-consuming. Rapid, sensitive online methods need to be developed, for which conventional GC techniques are not well suited. If species of interest with similar mass spectra do not need to be separated, membrane inlet mass spectrometry (MIMS) is perfectly adequate and fast. 

Membrane Inlet Mass Spectrometry (MIMS) Instrumentation for... 

Riter et al. applied Membrane Inlet Mass Spectrometry (MIMS) coupled to a miniature mass spectrometer equipped with a cylindrical ion trap (CIT) analyzer to monitor the flavor components directly from human breath [6], Johnson et al. measured ethanol concentrations on-line in fermentation broths from a 9000-L fermentation reactor for a period of four days [7], However, data reported in the above papers referred to experiments lasting no more than a few days. 

Comparison of Membrane Inlet Mass Spectrometry (MIMS) with Purge-and-Trap/Gas Chromatography (GQ/... 

Membrane SLM MESI MMLLE MIMS PME HF-LPME MASE LGLME Headspace-solid phase dynamic extraction (HS-SPDE) Purge-and-membrane extraction Headspace/membrane extraction w. sorbent interface (HS-MESI) Headspace/membrane inlet mass spectrometry (HS-MIMS)... 

ARA, acetylene reduction activity MIMS, membrane inlet mass spectrometry. 

MEVIS/IPM, membrane inlet mass spectrometry/isotope pairing method TCD, gas chromatography-thermal conductivity detector AIT, acetylene inhibition technique IPM, isotope pairing method with isotope ratio mass spectrometry MIMS, membrane inlet mass spectrometry Stoichiometery, benthic flux DICiDIN stoichiometry MIMS + N03, membrane inlet mass with N03 amendment 15N2 production, 15N03 or 15NH4 conversion to 15N2. 

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. 

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. 

MIMS membrane inlet (introduction) mass spectrometry... 

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