Chromatography Forum

Dear all,
I am new to the GC stuff, so please excuse my silly questions!

I checked our heritage of Varian GC-MS spare parts and I found several spare parts purchased more than 10 years ago. I am particulary concerned about the shelf life of these spare parts. We have Ferrules, O-rings, nuts, inserts, septa and some spare parts for the MS such as filament and multplier assemblies.

From your experience, is there a shelf life for any of these?

Thanks in advance.

O-rings and septa might degraded. But may be useful as well.

Multipliers have a shelf life and should not be exposed to air and light.

Thanks a lot dblux_ and Cleh.

I am worry more about the septa and the liner. I checked the liner which was fitted in the injector for years and I found a lot of small red particles which I think came from the septum! I replaced it and replaced the septum with a new 10-years-old septum but I think it was too late! I now get several peaks in the chromatogram with each run, even with no injection. Using the MS, most of them were identified as Siloxanes and Phthalates compounds. I cut about 50 cm of the column end that is connected to the injector but the problem still the same.

I want to replace the column with a new one but I am worry if the problem is still in the injector, which mean contaminating the new column.
My method is using 300 oC for the Injector and column.
What you may do in such case? Any advice is appreciated.
Many thanks in advance.

I would throughly clean the inlet, including swabbing it out with solvent. The phthalates have probably migrated along surfaces over the past ten years. Unless someone kept the instrument under carrier flow for the past the years, the column has been exposed to air - and may be the source of the siloxanes as a result of degredation. If thecolumn has begun to degrade, it will only continue to degrade.

How was the instrument prepared for storage? If gas lines were capped off with metal caps, good. If wrapped with plastic tape, there could be phthalates in the gas lines from migration from plastics.

Places that are likely to have been contaminated are best stripped with solvent, if possible. Then, with carrier flow on, see if the flow of gas will carry away remaining contamination. Phthalates moving to the column are not a problem for the column - they elute. They are a problem if they are in the plumbing ahead of the column becuase they migrate and accumulate on the head of the column between runs.

Thank you Don_Hilton.
The instrument has been installed more than ten years ago. However, it is rarely used. It used to stay off for months or even a year. When required, it is switched on and baked out then calibrated and used. After a week or so, we cool it down and switch it off. We keep the lines connected but no carrier is run.

I am afraid if this procedure can affect the instrument.

Regarding cleaning the inlet, do you mean the liner only? or the whole injector? If it is the whole injector, is it just by disconnecting the column and flushing some solvent through the inlet?

Also, is the liner considered a consumable or we can just clean it with a solvent and use it again?

Sorry for these basic questions!

Discard the liner and clean the inlet. You will need the instructions for the particular instrument as to how to do this. I am more familiar with Agilent instruments and in them there is a seal plate on the bottom of the inlet which you remove and replace wiht a new seal plate.

Liners are conumable items. And I would use a new liner. If you have several that are the age of the instrument I would be concerned that phthalates may have migrated out of the plastic containers and onto the clean liners. The older stuff may be good - but, let's avoid creating questions while trying to answer one.

Many thanks Don,
I will check the manual to do the cleaning and I may order a new liner as all what I have are AGED ones!

Thanks for all.