Problem with head space carry over test!

[stefavramov]

Hello I work in pharmaceutical company and every year we make validation tests of the equipment-1 GC Shimadzu-2014 and Head space Perkin Elmer - Turbo matrix 40. So the problem is with the Head space carry over test. There is a manual of the manufacturer which we follow to perform the leak test, and also there is a formula and with her we should calculate how much is the carry over. We follow all the requirements but in the end the result of the carry over is very big-about 0.3% (it should be not over 0.15 %). So I want to ask if someone know where is the problem and how can we solve it? Is it possible to be in the transfer line which connect the head space with the GC. We never change it since we buy the apparatus. And also I know that it is expensive- about 1000 euro. I hope that someone can know how to solve this problem.
Thank you for your answers.

[chromatographer1]

Dear, Stefavramov,

It is likely that the transfer line's deposits are the problem here. Cleaning may resolve the problem. Often fused silica tubing is placed within the transfer line so when contaminated it can be replaced easily to restore a clean passageway.

A spare transfer line might be a good idea so a clean line can be installed to minimize the instrument down time as the dirty transfer line can then be cleaned while work continues.

best wishes,

Rodney George
consultant

[GaryR]

Hi Stefavramov

We have three PE headspace samplers. Every time we've had a problem with carry-over it has been traced back to the needle. Try changing your needle and see how it goes.

That sounds like a LOT for a transfer line. You can use a piece of retention gap (GC column with no liquid phase) cut to length. Easy to change and cheap (just make sure it's the same id as what you are currently using). You could try this first because the needles are quite expensive. But I think you'll find the needle is the problem.
I haven't yet found a way to clean them out either, only way is to replace.

Let us know how you go.

Gary

[Yuva]

Check the purge flow HS. It should be around 15 ml/min. During the injection period the purge flow should stop.

You have to locate the problem in GC or HS.