Headspace sample injection for GC and GC–MS is a mature technique that is used in a wide variety of applications. However, some aspects of method development for conventional static headspace can be time-consuming.
A particularly important consideration is the injection volume, which can be limited by either injector loop size, injection time or capacity of the injection liner (and exceeding the liner volume can cause chromatographic problems, especially for early-eluting compounds). One solution to this problem is to use a split flow, which may give better chromatography, but results in less sample reaching the detector. Balancing these factors can be difficult, and add significant time to method development.
Such difficulties can be overcome – and the applicability of headspace extended – by using a focusing trap prior to injection into the GC. In this study we show how the focusing trap in the Centri® automated multi-mode platform allows efficient preconcentration of headspace samples, even for large volumes in splitless mode.
This focusing trap can contain a variety of sorbents, and using ambient or sub-ambient temperatures, can efficiently trap VOCs released from a sample. The trap is then ballistically heated (up to 100°C/s) in a reverse direction to transfer the analytes to the GC in a small volume of carrier gas (~100 μL), resulting in a tight band of analytes at the head of the column and sharp chromatographic peaks, even using low-split or splitless modes.
>> Download the full Application Note as PDF
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