Centri - GC x GC - Exploris 240 Orbitrap HRMS

The infrastructure is an integrated versatile platform for steel preparation, 2-dimensional gas chromatographic separation and Orbitrap mass spectrometric identification and quantification of (semi-)volatile organic compounds, in short (semi-)VOCs, in natural and technical environments. Many of these components are important air and water pollutants and pose a threat to our health and the environment. In addition, (semi-)VOCs play a crucial role as secondary metabolites and/or signalling molecules in ecosystems, as well as in the preservation of food.

To study and understand the underlying molecular processes, it is necessary to ensure reliable identification and quantification of (semi-)VOCs in various complex matrices at trace level concentrations. Therefore, the infrastructure provides flexible, robust and automated capabilities for both steel pre-preparation and advanced instrumental analysis:

(i) Sorbent-based enrichment procedures are crucial to obtain sufficient sensitivity given the (usually) very low concentrations of (semi-)VOCs. Through the Centri unit, the infrastructure offers the possibility, depending on the type of sample, to make the right choice of enrichment technique using sorbent tubes (followed by thermal desorption), solid-phase microextraction (SPME), Hisorb, headspace or direct liquid injection.

(ii) After sample enrichment and purification, gas chromatography is the analytical technique par excellence for separating individual compounds, given their high volatility. Single-dimensional gas chromatography (GC) is not always sufficient for complex samples. Two-dimensional gas chromatography (GCxGC) provides the ability to separate structural isomers and generates structured chromatograms (due to orthogonal separation at both boiling point and polarity) that can be used as two-dimensional fingerprints to support identification.

iii) Linking GC with advanced mass spectrometry (MS) is necessary for detection, identification and quantification of (semi-)VOCs. In order to be able to identify molecules with the highest possible degree of certainty (elementary and structural) and to quantify them as accurately as possible, the high-resolution mass spectrometer (HRMS) provides the possibility to separate ions with a resolving capacity of 240000. This makes it possible to determine the elementary compositions (gross formulas) of unknown molecules with high reliability, which facilitates the identification process. High-resolution mass spectrometry also allows more selective (targeted) detection in complex mixtures.