Flame sealing of GC columns?

[MiroK]

Dear all.
I have developed an analytical method using GC column, that is very sensitive towards any moisture. According to manufacturer, stationary phase of this column will hydrolyse in the presence of water from the air. They are recommending, that the column should be flame sealed for a long-time storage.

As I know, GC columns are made of fused silica, which have high melting point (1750 C according to some data) and usual laboratory burners are just not hot enough. Does anyone have any experiences with flame sealing GC columns? Could you recommend suitable burner, that could be used in the lab for this task?

Miro

[Consumer Products Guy]

Most would stick the capillary column ends into a used septum to exclude moisture and air.

[chromatographer1]

If you have the proper flame tip and burner for a hydrogen flame, and a source of hydrogen fuel gas, a hydrogen flame will seal fused silica.

The hydrogen flame when properly mixed with air will be almost invisible. Be sure to wear special eye protection from the large amount of eye damaging radiation from the hydrogen flame.

With these safety concerns being so intense, why use a flame?

A dab of glue is a simple closure as well as the commonly used piece of silicone septum rubber already mentioned.

Be safe ! Be careful !

best wishes,

Rodney George

[Peter Apps]

An oxy-butane/propane flame as used by glass blowers and jewellers will easily seal fused silica, you might even manage it with one of the fancier mini blowtorches (butane/propane with air).

If a silicone septum is not good enough have a look at the column end caps that Restek sells.

Peter

[DR]

Kitchen butane torches are also hot enough, though I would use either an old septum or a glass union.

[MiroK]

Thanks for your contributions. The column is Astec Chiraldex A-TA. The manufacturer is recommending, that the column should be flame and not septa sealed for a long-time storage. I am quoting: "Sealing ends with rubber septa is not effective for keeping oxygen and water vapour out of the column and should not be used". I have already found out, that acetylene/oxygen flame forks fine. I did it in our company's workshop by welding torch, today. However (again by manufacturer's recommendations), it should be done while one end is still attach to the GC under carrier gas flow... Therefore I would like to have a portable burner. I will try butane/propane torch next.

To understand, why I found this question very important I would like to give you some more data: The method was developed on the new column, which was flame sealed when shipped. At that time separation between two enantiomers was good. However, after one month of storage (sealed only by septa), separation has been deteriorated.

Does anyone have any experiences with Astec Chiraldex A-TA, B-TA or G-TA columns?

Miro