GC capillary tubing – things you may not know

The other day a customer asked me about our GC capillary tubing specifications, and was surprised to learn that the outside diameter (OD) of both 0.25 mm and 0.32 mm internal diameter (ID) MXT tubing is almost the same (0.41 mm & 0.44 mm), while our 0.28 mm ID MXT tubing has a larger OD of 0.56 mm. He was not the first person surprised with those facts.  For reference, the table below lists tubing ID, OD and OD +/- ranges.

 

Another common question we get asked in tech service is which product we recommend for cutting GC capillary tubing.  I personally suggest a ceramic wafer (pictured below is catalog number 23015).

One last common question concerns the color of fused silica tubing.  Keep in mind that fused silica is actually a clear glass; the color you observe is caused by the polyimide coating (which gives the tubing its flexibility).  Colors can range from a bright yellow to black.   Don’t be concerned if your columns vary in color, performance is not affected.

I hope you have found this post helpful.  Thanks for reading.