Broken fused-silica columns – it’s rare, but it does happen.

Once in a while we get a call that one of our GC fused-silica columns has broken, and customers ask if it can be repaired and used.  The answer is “maybe”.

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If your column broke while at a high temperature, and the column’s phase has been exposed to oxygen (air), then probably not.  A sure sign of an oxidized phase is high column bleed and/or poor peak shape due to activity.

If it broke while at a low temperature, say 50°C, the column’s phase is probably OK because oxidation occurs very slowly, if at all, at these temperatures.  The only way to know is to repair (as described below) and test the column.

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So how should you repair a broken column?  Well, you may not know but when a column breaks, stress fractures are created which travel down the fused-silica tubing.  Therefore, we suggest trimming at least 12 to 18 inches from each broken end using the smooth (flat) edge of a ceramic scoring wafer.  Once trimmed, connect these ends using a glass Press-Tight® Connector, a Vu2-Union Connector, or a MXT-Union Connector.

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Once repaired, purge the column with carrier gas as described in this post on How to Condition a New Capillary GC Column.  Of course you don’t need to condition your used column, so inject one of your chemical standards and observe compound peak shape and baseline.  If both look fine, you should be able to use your column.

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So why do fused-silica columns break?  If the polyimide coating gets scratched, it creates a compromised section of tubing.  It doesn’t take much for it to break if damaged.  On the rare occasion where the tubing may have a small surface defect, the break almost always occurs here at Restek when we manufacture the column, so very few columns ever leave the factory which break afterwards.  An exception to this statement is very high temperature analysis.  This is why I usually recommend our MXT Columns for analytical methods which incorporate oven temperatures greater than approximately 360°C and/or extended final temperature hold times above 340°C for 10 minutes or more.  MXT columns are also recommended when a small coil (outside diameter) is needed and when using portable GC’s.

If your new columns breaks shortly after installation, contact us.  Please have the column catalog number and serial number handy.

I hope this has helped.  If you have any questions, email us at support@restek.com

3 Responses to “Broken fused-silica columns – it’s rare, but it does happen.”

  1. jaap says:

    Thanks Alan
    One additional comment which is a practical observation that I do not hear a lot about. Fused silica columns also tend to become fragile at the injection side, when there is loss of phase and/or deactivation due to injection conditions or/and sample matrix. Such sections of exposed bare fused silica surface, can become fragile upon sudden big pressure changes. It can happen when a column is removed and one forgets to turn the flow/pressure off before disconnecting. The same will happen with non-deactivated fused silica tubing. It’s very important always to use deactivated tubing.

  2. Travis Weaver says:

    I recently had an DB-5 column snap on me, but I think it was due to age. 30m x 0.32mm x 0.25um used for diesel analysis for two years, held at 320C for 10 minutes each run. When I went to clip the column, it just shattered, so installed a new one.

  3. Alan Sensue says:

    Hi Travis:

    Thanks for reading my post. In your case, the polyimide coating probably started flaking off (which you may not have even noticed), leaving the fused-silica tubing vulnerable. If this happened along the entire column length, which it probably did, their really is no way to repair the column, and it is time to purchase a new one.

    Alan

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