Air Columns – Part III: My favorite column phase for EPA Method TO-15!

In part I of this blog series I told you my theory on why most air laboratories are using a 60 m x 0.32 mm x 1.00 µm 1-type column to separate what I refer to as the standard suite of 65 VOCs for U.S. EPA Method TO-15. Then in part II I showed you 5 examples of 30 m columns being more than sufficient to separate the standard suite. Now… which one of the 5 phase types do I like the best… drum roll please!!!

The Rtx®-VMS with full details here: http://www.restek.com/chromatogram/view/GC_AR1153

Why? Well… for the following reasons

  1. It is da bomb! (yes… that is a highly technical chromatography term)
  2. It is the one and only column on the market that was purposely developed for volatiles.
    1. VMS = Volatile Mass Spec
  3. The polars (especially ethanol and IPA) look the best (i.e., no hint of tailing) relative to the other phase types.Ethanol VMS
  4. Butane and 1,3-butadiene (isobaric) do not coelute.Butane & 1,3-Butadiene VMS
  5. All of the 65 components spread out evenly across the GC run, with no critical coelutions; and recall that this is accomplished with a very simple GC program utilizing close to speed optimized flows (SOFs) and optimal heating rates (OHRs) up to 150 °C.
    1. Yes, you can achieve this with the 1 and the 5, but you have to do a little bit of work.

So there you have it folks, the VMS. Now to be 100% honest and divulge everything… my favorite air column is actually a 30 m VMS, but in the 0.25 bore. YUP… that’s right! And you thought I was crazy with the 30 m deal. Now a 0.25 bore instead of a 0.32? Too many air labs are entrenched in 60 m columns, so I thought I would ease everyone into the length part first. Down the road we can talk about bore, so stay tuned!

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