51
Inert GC Flow Paths Have Never Been More Critical
by Ken Lynam - Agilent Technologies, Inc, 2850 Centerville Rd, Wilmington, DE 19809-1610, USA
As available samples become increasingly active, and more complex, you simply cannot afford interferences caused by flow-path activity. A flow path that is not inert can cause peak tailing and signal loss. You can lose critical sample components, leading you to believe they are not present. In addition, the need to repeat or verify suspect analyses wastes resources, hinders productivity, and hurts your profitability. Even worse, unreliable results can have catastrophic implications for environmental safety and food quality, and can lead to inaccurate results in drug abuse analysis. To achieve the lower detection limits demanded by increasingly stringent regulatory obligations, and to confidently quantify active analytes, you need the most inert flow path possible.
Where is the problem?
Every stage of the flow path can degrade your results, from the inlet liner to the ion source.
What is the solution? Here are five tips for GC flow path inertness, so you can be confident that nothing has been added to or lost from your sample, even when components are present at trace levels.
1. Maintain the inlet Preventive maintenance helps to ensure the best instrument performance and productivity. To eliminate leaks and minimise downtime, inspect and replace worn or dirty GC supplies, such as syringe needles, septa, ferrules, and inlet seals. Use certified vials, caps, septa, ferrules, and gold inlet seals to extend the inertness of the GC analysis. If you use heavy matrix samples, such as forensic or environmental, then a strict regime of inspection and replacement to maintain cleanliness is even more important.
2. Prevent sample loss at injection Inlet liners are critical links in the sample flow path. Using glass wool in liners can trap non- volatiles and extend column lifetime. However, improperly deactivated liner and glass wool can result in loss of analytes due to the presence of active sites on the liner wall and in the wool. For samples with labile or active compounds use only highly deactivated liners. You can see the effect of using a liner with active sites in Figure 1.
Figure 1: How active sites in the liner can degrade peak shapes and analytical performance
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