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Indicating Oxygen and Moisture Traps-“Hey, it looks like my trap arrived partially spent”

  • Robert Wiedemer
  • #Troubleshooting
  • #Gas Purification
  • #Blogs
  • #GC Accessories
  • #Accessories & Labware
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The Restek Technical Service group occasionally receives questions from customers who receive their Indicating Oxygen Trap, cat. #22010 or 22011, and they are concerned that it arrived partially spent. This is because the material inside is black on both ends with a green colored material in the middle of the trap. The green material is the indicator that will change to gray when exposed to oxygen. The black material on either side of it is not indicating material, it is black both before and after exposure to oxygen. When the green material changes color it will turn gray, not black, and you will still be able to see the difference between the indicating material and the non-indicating material.


Restek also sells Indicating Moisture Traps, cat. #22014 and 22015, with the same design, having the indicating material towards the middle of the trap and non-indicating material on both ends.



In both the Indicating Oxygen Traps and the Indicating Moisture Traps, the non-indicating material, which has a higher capacity than the indicating material, makes up the majority of the trap.

Both the oxygen and moisture traps have brass fittings on each end, which means they should be used with copper tubing, not stainless steel, as explained in note #1 of “I need a fitting, but which one?” It is also important that all cylindrical gas purifiers should be mounted vertically which will assure the gas flows through the material inside the trap. If a trap is mounted horizontally it is possible the adsorbent in the trap will settle, creating a “path of least resistance” above the adsorbent bed.

GC carrier gas purity is very important for the life of your column, as described in the blog posts “How to Increase the Life Time of your GC Columns? Part I: The Carrier Gas” and “How Long Will a GC Column Last?” and using a gas purifier on your gas lines is highly recommended. Restek offers a complete line of products for gas purification for carrier gas as well as for FID fuel gases.

Thanks for reading!