Chromatography Forum

Dear all,

I am using manual injection needle (Hamilton, point style 2, needle guage 26 or 22) to inject samples.

Almost everytime I insert the needle through the septum, the needle will "tear off" a tiny bit of septum, causing the plugging of the needle.

Is there any tricks to avoid this problem? (Am I over-tighten the septum retainer nut to cause the above problem?)

Thanks in advance.

Hi Anthony

The point style that you have is the worst option for septum damage. I cannot understand why syringe manufacturers continue to offer them as their default option.

Go for a domed or cone tip, or even a square end with the corners taken off with very fine abrasive paper.

You might also be tightening the nut too hard - make it just tight enough to re-seal after an injection when it has warmed up to working temperature. If you tighten with the septum cold it will be too tight once it has expanded with the heat.

Peter