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Conditioning GC Inlet Parts


Conditioning is a critical step in gas chromatography that helps to remove contaminants. Many people have been conditioning their columns for years but may not realize it is also important to condition the inlet after installing new consumables like liners, inlet seals, and O-rings. Replacement parts may have contamination from their manufacturepackaging, or even laboratory gloves, and a short inlet conditioning is a very effective way to drive off this contamination and reduce any impact that it might have on your analysis.

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Welcome back for another Restek Tip. In today’s tip, we are going to discuss the importance of inlet conditioning and how an unconditioned inlet could affect your analysis.

Whenever you install new inlet products, no matter who the manufacturer may be, there is always a chance that the parts could have some small degree of contamination. Contamination can occur from plastic packaging, oils from a person’s hand, or even laboratory gloves. Because of these numerous contamination sources, whenever we replace parts such as liners, it is very important that we bring the inlet up in temperature for 10 to 15 minutes in order to drive off any unwanted volatile or semivolatile compounds. If the inlet is not conditioned after replacing parts, we could see interferences in our runs, which come in the form of high background noise for our early runs. For example, here is a chromatographic overlay where we see peaks caused by finger oils during the first analysis. In the second analysis, these peaks are no longer there.

In another example, you can see the benefit of baking out your liner before you start running samples. Over time at high temperatures, the noise caused by small amounts of contaminants on the liner is drastically reduced. While you may be tempted to jump in and start running samples immediately after replacing new inlet parts, remember that this could cost you more time and money in the long run. By conditioning your inlet, you can eliminate background peaks and avoid costly reanalysis. This will also help you improve reproducibility and system performance.  

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