Chromatography Forum

Hi there,

I am using a supelco SP-2560, 100m x 250um x 0.2um column for FAME analysis (using FID) and after prolonged use it has shown peak tailing. The normal tail is 0.15 mins and now it has a 0.4 mins long.

Any idea how i can regenerate the column?

I had cut front and back column 10cm.

Not yet clean the liner, gold-sealed plate and detector.

As the manufacturer stated in the product cert, it is not suggested for solvent rinse. So far i havent rinsed the column, mostly injecting standards and samples.

Max temp tolerance is 240oC for this column as stated.

Thanks very much.

Hi there,

I am using a supelco SP-2560, 100m x 250um x 0.2um column for FAME analysis (using FID) and after prolonged use it has shown peak tailing. The normal tail is 0.15 mins and now it has a 0.4 mins long. Is this the tail on the solvent peak ?

Any idea how i can regenerate the column?

I had cut front and back column 10cm.

Not yet clean the liner, gold-sealed plate This should be the first thing that you do - the inlet is a much more likely source of trailing than the column. Inlet maintenance needs to be part of your regular proceduresand detector.

As the manufacturer stated in the product cert, it is not suggested for solvent rinse. So far i havent rinsed the column, mostly injecting standards and samples.

Max temp tolerance is 240oC for this column as stated.

Thanks very much.

When did you last change the inlet liner and gold seal ?

Peter

I had changed the inlet liner about 60 to 70 injections (2 weeks uses) before.

About the gold-sealed plate, I had never changed it since my company bought this GC-FID Sep of 2010.

I think i had used this GC column for about 9 months to 1 year, and tailing problem started to be severe just about 3 weeks ago (120 injections).

I would guess the column was heated too long near the max temperature. I wish to EMPHASIZE that a temperature limit is not like walking along a cliff. One foot inside and all is well. One foot past the limit and you take a fall.

Especially with non-bonded phases, getting near the limit (10-30 degrees near) you start losing the phase stability and 'beading' of the phase which can cause tailing and poor efficiency of the column.

There is no way to recover a damaged column. If you remove 10m from the head of the column it may be ok for the final 90 meters, or it all may be bad.

Since I assume you may have over 100 hours at temperatures over 200C you should consider that a decent return on the price of the column.

Removing 10cm won't do much in my experience. 3 to 10 meters would be a better choice.

Good luck.

Rod

Thanks for the advices.

I will try cutting more column and see if there is any improvement.

I have one more question in mind,

I was told, while installing the column to the detector end, do not insert all column into it but leave a gap for it (push to the end, pull back a little 5 - 10mm).

One time i forget to follow and results in diminished and tailed peaks.

Why is that?

Putting the column into the flame burns off the phase and leaves a very active surface at the end of the column.

Follow the instructions of the manufacturer when installing a column.

best wishes,

Rod

Thanks.

Hi All,

We are experiencing some problems with certain peaks on the same column with GC-FID. C20:5 swaps its place with C24:0(this happens after about 100 injections) after C20:3 swaps its place with C22:1 (this after 150-200 injections), after C20:1 swaps with C18:3 (not long after the other two). We do general maintenance (trimming abou 50-100cm off, liner cleabing, O-ring, gold plated inlet seal replacement) at least once a week. We run 15-20samples a day. Do you know what can cause this problem?

Since this extremely polar phase cannot be bonded to the column surface, every time the column is heated, especially near the maximum limit, the phase will tend to bead, exposing the non-polar surface of the fused silica.
This changes the selectivity of the column and produces the change in peak order you see.

The more heat the column receives, the worse the effect becomes.

Columns are like automobile tires, they wear out and don't last forever.

Rod

Thank you very much for the anawer.

Would you be able to suggest me an oven tempretaure program and settings to the gc and fid I could try out? Do you know anyone who experienced the same problem? And do you know what there solution was?

Thank you