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Total-transfer, valve-based comprehensive two-dimensional gas chromatography [An article from: Analytica Chimica Acta]
Description
This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Valve-based comprehensive two-dimensional gas chromatography (GCxGC) is one of the most compact, robust, and inexpensive GCxGC instrument designs. The major drawback of a valve-based modulation configuration lies in diminished detection sensitivity. This loss in sensitivity is because under typical operating conditions the fraction of the first column (i.e., column 1) effluent transferred to the second column (i.e., column 2) is likely to be ~5-10%. To address this loss in sensitivity, we report the development of a unique total-transfer (i.e., 100%) valve-based GCxGC, without adding complexity to the instrumentation. The new instrument design relies upon simply blocking one of the appropriate ports of the high-speed six-port diaphragm valve that is used as the modulator between columns 1 and 2. The modulation period and difference in head pressure between columns 1 and 2 are found to be the two primary variables that are controlled to provide good detection sensitivity and 100% mass transfer from column 1 to column 2. The detection sensitivity is better with a longer the modulation period. A limit of detection of 0.03ng/@ml was obtained for octane. This sensitive GCxGC configuration is also shown to provide acceptable separation peak capacity, with good separations achieved for real complex samples: gasoline and Eucalyptus oil, where compounds were spread out over much of the two-dimensional separation space. In principle, this total-transfer, valve-based GCxGC is more portable and less expensive than currently available GCxGC instrumentation.
Description:
Valve-based comprehensive two-dimensional gas chromatography (GCxGC) is one of the most compact, robust, and inexpensive GCxGC instrument designs. The major drawback of a valve-based modulation configuration lies in diminished detection sensitivity. This loss in sensitivity is because under typical operating conditions the fraction of the first column (i.e., column 1) effluent transferred to the second column (i.e., column 2) is likely to be ~5-10%. To address this loss in sensitivity, we report the development of a unique total-transfer (i.e., 100%) valve-based GCxGC, without adding complexity to the instrumentation. The new instrument design relies upon simply blocking one of the appropriate ports of the high-speed six-port diaphragm valve that is used as the modulator between columns 1 and 2. The modulation period and difference in head pressure between columns 1 and 2 are found to be the two primary variables that are controlled to provide good detection sensitivity and 100% mass transfer from column 1 to column 2. The detection sensitivity is better with a longer the modulation period. A limit of detection of 0.03ng/@ml was obtained for octane. This sensitive GCxGC configuration is also shown to provide acceptable separation peak capacity, with good separations achieved for real complex samples: gasoline and Eucalyptus oil, where compounds were spread out over much of the two-dimensional separation space. In principle, this total-transfer, valve-based GCxGC is more portable and less expensive than currently available GCxGC instrumentation.
