Chromatography Forum

Hello everyone

I am analysing small organic acids in urine for diagnosis of inborn errors of metabolism, using an Agilent 5975C GC-MSD.

I replace the inlet liner almost every week. Replacement of liners gets expensive. I was wondering if anyone knows a way to clean - re-deactivate liners(solvents, procedure) in order to re-use before I throw it away.

I found in the topic "Liner restoration" that re-deactivating liners can be made like this:
"take a solution of 10% vol DMCS or DMDCS in toluene and bath it for few minutes. Thats the deactivation. But don't touch the solution with your fingers!!"

I have the following questions:

1. What about cleaning?
2. How many times can I use the same liner, after cleaning - re-deactivating?
Any help would be much appreciated.

Many thanks:)

Cleaning will depend on the kinds of residues left in the liner.

If you use liners with glass wool, I would suggest removing the glass wool before cleaning and replacement before deactivation. (placing deactivated glass wool into an inlet liner tends to result in broken ends of the glass wool fibers being exposed - and they are very active.)

You will also need to perform QC on each batch of liners you condition. (I have been discouraged from cleaning and reusing liners - particulary as the cost per samle as compared with solvents and all the other consumables in an analysis is typically so small.)

Don Hilton,
I would like to thank you for your reply. I really appreciate it.
I am using liners without glass wool. They have some kind of spirals.
I always take into consideration all that you've given me.
I'll be around:)

Have you considered a simple liner with glass wool? They are half the cost of the liners with the built in spiral? There are some kinds of analyses that need the more expensive liner - but if the less expensive liner has not been tried for your method, I would suggest a brief study to see if it will work as well for you.

Also, if you are making a split injection, you may consider diluting the sample and making a splitless injection. You get the same quantity of material on the column and a fraction of the dirt in the inlet. (You have to be careful in selecting the purge off time to avoid discriminiation.)

Years ago I was working in a lab where we reused liners. We used quartz liners, soaked them in a dilute nitric acid solution when they were not in the instrument, changed the liner 2 or 3 times a week, and injected a high concentration sample before using the instrument for samples to tie up active sites. This whole process was probably more trouble than it was worth because it was not rare for the check standard to fall out of the acceptable range after changing liners, and then we would have to try another liner.

Have you tried the Restek Siltek liners? We've had good luck with them staying inert longer than traditional liners with only a small increase in cost.

I used to soak liners in dilute acid, rinse with water, rinse with methanol, rinse with hexane, soak in dilute DMDCS, rinse with hexane, rinse with methanol, oven dry. I would do 5-10 at a time and store them in a VOA vial. Tedious but effective back then.

Best regards.

the liners with the spiral in them are almost certainly Restek CycloSplitters...I love those things!

In my lab, the labor involved in cleaning and reconditioning a handful of liners would be way more expensive than just buying new ones. How much is your time costing your organization?

The cleaning procedure I used way back when was to soak the liners in hot chromic acid (danger! danger!), rinse the heck out of 'em, then treat them with a Silane substance called...Sylon CT? I think that was the name. It took all day, and each batch was slightly different from the last, as someone mentioned earlier.

All in all, I'm not sure it would be worth your time to carry out such a procedure, from a lost production, labor-cost point of view.

I would like to thank you all very much for your responses. The knowledge that this forum provides is so helpful. I'm really glad about it.
We'll be in touch