Download GC/MS : A Practical User's Guide

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INNOVATION IN GC/MS
field-portable GC/MS from Indicon, Inc. weighing 37-lb and can be worn
over the shoulder to create a man-portable GC/MS. It uses a pumped sampling
wand and can be operated for about 10 min to analyze a wide list of
compounds that can be analyzed with a NIST spectral database.
The www.gcms.de. web site lists a number of microsystems based on other
types of mass spectrometers. Griffin Analytical Technologies has a breath
analyzer based on a cylindrical ion trap, as is the Chemical Biological Mass
Spectometer (CBMS) from Bruker. Kore offers a fire scene investigation
system called MS-200 based on a time-of-flight mass spectrometer.
Portable GC/MS systems come in a variety of sizes. They start out as
transportable units that fit in the back of a pickup and are powered by the
truck’s 12-V battery system. Luggable systems, like the Hapsite unit, are
versatile systems designed for general Hazmat and first response analysis of
toxic spills and suspected chemical warfare sites. Smaller handheld units
generally are targeted at very specific analysis, such as bomb and explosive
sniffers or breath alcohol and drug analyzers.
16.5 NEW COLUMN TECHNOLOGY
Monolith and micro-WCOT (wall-coated open tubule) columns are the
bleeding edge of new GC column technology. Monoliths and micro-WCOTs
are not packed columns, but are prepared in situ in open tubule and capillary
column casings. In monoliths, the interior of the capillary tube is completely
filled with either a polymeric or silica foam with interconnecting pores.
The porous foam structure can be coated with a viscous liquid phase or
permanently reacted with a bonded liquid phase. Micro-WCOT column
eliminates the solid support structure and reacts the organic-bonded phase
directly to the walls of the column to prepare a brush phase directly adhering
to the wall of a ultrasmall diameter column.
Organic polymer monoliths were first prepared in the 1990s by polymerizing a cross-linked monomer in the presence of a poromeric liquid. After
polymerization catalyzed either chemically or with UV light, unreacted
monomer, catalysts, and the poromeric liquid are washed out with an organic
solvent such as tetrahydrofuran. Functionality can be added to monomeric
column by selecting monomers with the desired side chains. Because the
foam completely fills the column, diffusion effects due to void volumes are
avoided leading to much high column efficiency.
Silica monolith columns began to appear early in 2002. Tetraalkyoxysilane
is polycondensed in the presence of porogenic liquid such as poly(ethylene
glycol). After washing out the porogen, the monolith is left behind as a stiff