Volatile Mixture Analysis by Repetitive Injection Fast Gas Chromatography/Mass Spectrometry

Abstract

An apparatus designed for repetitive sampling and characterization of evolved gas mixtures generated during thermal analysis is described. The apparatus combines fast temperature ramp gas chromatography separations with mass spectrometric detection to selectively monitor volatile mixture component concentration changes as a function of sample temperature. The apparatus was tested by using it to repetitively sample and analyze the volatile products generated when poly(styrene) was catalytically cracked by an HY zeolite solid acid catalyst by heating the polymer/catalyst mixture in an inert helium atmosphere. Eleven mixture components contained in the gas stream were separated and detected at 90-s intervals when the polymer/catalyst sample was heated from 200 to 400 degrees C. Mass spectral extracted ion chromatograms were employed to generate species-specific evolution temperature profiles, which provided insight into thermal reaction mechanisms.

Characterization of ultra-thin polymeric films by Gas chromatography-Mass spectrometry hyphenated to thermogravimetry

“…To guarantee the performances of the global setup we initially focus on the synchronisation of the working conditions of each instrumental components [18], i.e. :…”

“…A modified validation procedure [12,18] was employed to quantify the performance of the TGA-GC-MS system. Accordingly, the calibration and the system performance evaluation were assessed by heating different amounts of a salt, that presents a well-known stoichiometric thermal decomposition reaction, and quantifying the evolved gas by the MS [20].…”

“…In the resulting TGA-GC-MS configuration, the TGA can operate to impart a precise and reproducible thermal history to the samples. Hyphenation of TGA with GC-MS allows the separation of the evolved gas mixture into single components [17,18] but in literature an application to ultra-thin film does not exist.…”

An Editor's View of Analytical Chemistry (the Discipline)

“…The analytical methodology for fast gas chromatography (GC) separations has evolved substantially, starting from a microcolumn etched into a Si wafer (22) in the 1970s to a significant volume of publications on fast GC applied to a wide variety of analytical situations at the present time (23)(24)(25). There are also commercial portable vapor and odor GC sensor instruments based on short columns and SAW device detectors that can complete separations and identification in less than 1 min (see http://www.estcal.com/products/model4500_portable_znose.html).…”

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“…If a chemical separation can be accomplished within a time comparable to the response time of a chemical sensor, or within the timescale desired for measurement of the chemical system or process, then such a separation tool is de facto a sensor (21). The analytical methodology for fast gas chromatography (GC) separations has evolved substantially, starting from a microcolumn etched into a Si wafer (22) in the 1970s to a significant volume of publications on fast GC applied to a wide variety of analytical situations at the present time (23)(24)(25). There are also commercial portable vapor and odor GC sensor instruments based on short columns and SAW device detectors that can complete separations and identification in less than 1 min (see http://www.estcal.com/products/model4500_portable_znose.html).…”