Chromatography Forum

Does anyone out there run Compendium Method TO-17?

My new position requires me to set up this method from scratch, and it would be very helpful to have some professional contacts who are running the same method! My EPA contacts have not been able to find me another TO17 lab so far.

This is a GC/MS method using a thermal desorber on the front end to analyze VOCs in ambient air collected on sorbent tubes.

My main questions are:
1. How do you load your standard tubes?
2. Have you ever bought pre-loaded standards as a system check? Where did you buy them?

Thanks!

I just read the EPA method and I can't believe they don't call out how you're supposed to do it in the method. Seems a little strange to me.

Markes sells this thing:

https://www.markes.com/Products/Samplin ... g-rig.aspx

I have a gizmo that I put together that works on this principle but I use a silco-steel, Swagelok reducer (threaded 1/4" on one side and 1/8" on the other end) and a half-hole, cylindrical septum on the other. I put a needle in the septum to vent the vacuum. After affixing my TD tube to the threaded side (with a nylon fitting, ferrule, and back), I inject my standard through the septum and pull the standard onto the sorbent in the TD tube by pulling 100 mL of air through it with a manual sampling pump:

https://www.markes.com/Products/Samplin ... mpler.aspx

The nylon fittings make a seal on the TD tube without compromising the tube itself (resealable).

Here's some data I generated for toluene using this procedure.

https://i.postimg.cc/J4MHYv4j/Toluene-i ... ration.jpg

You'd have to validate it for your with all of your analytes. I'll put up a photo of my gizmo and the part numbers I can find on Monday.

Here you go. There's only a part number on the septum (on the graphic). The needle is generic made by Becton Dickinson (I've had these for years), 20G1 1/2 short bevel. I don't know if Becton Dickinson exists anymore.

https://i.postimg.cc/ZRLcdZD5/Powerpoin ... ation1.jpg

This gizmo seems to work well for the analytes I've tried. Perhaps you can make it work too?

I still don't understand why the EPA method doesn't call out how this should be done in the method.

I was a little suspicious of how my technique would work for something like naphthalene (on the TO-17 "special" list). It is a solid at RT. Not bad:

https://i.postimg.cc/yNRw3XQn/Naphthale ... ration.jpg

I might need to come up with a way to warm the fitting as I pull the air through it to load the tube.

I went back and did the naphthalene experiment again but this time, I heated the silco-steel fitting for 30 minutes in my vacuum oven (60 °C) before I prepared the first standard (the highest loading). Between standard preps, I heated it again for 5 minutes. The goal here was to keep the fitting warm while loading the tube with naphthalene. The results were quite a bit better:

https://i.postimg.cc/x8jzC9kH/Naphthale ... ion-II.jpg

This is seeming like a pretty good option for loading tubes with standards. It'd proabably be good enough for me in my work. Perhaps someone more tied to regulations might not like it.

Wow, thank you for the detailed responses, rb6banjo! I didn't get the notifications that anyone had responded!

I'm unable to access your links here at the lab due to our internet restrictions, but hopefully I can find time to access them at home. TO17 has been on a far back burner recently after we got a new GC/MS forto set up and validate a different method. I'm hoping I can return to my TO17 efforts by the end of the year.

Thank you and have a Happy Thanksgiving!