Unused BPX70 stability

[Peggsy]

Hi all

We have a student here who has stored a BPX70 column in its original box at ambient temperature with no end plugs (has never been used).

We can't find anything in the column manual concerning the lifetime of such a stationary phase at ambient conditions, can someone please let us know if there is a rule of thumb that the BPX70 column can be stored for before it degrades? We have ran this column recently and compared to the older BPX70 the separation/resolution is far worse in the stored column, in fact now at the same GC conditions unusable.

hope that makes sense!

Regards
peggsy

PS it has been stored at ambient for some 10 years!!!!

[gcguy]

I would be tempted to try it. The column may have become brittle and the phase may be wrecked but you will never know until you try it.

Gcguy

[Bruce Hamilton]

It should work fine. It's a 70% Cyanopropyl polysilphenylene-siloxane
phase, and long term storage at ambient should be OK. I've used SGE columns that are 20 years old. You could ask the manaufacturers, they should be at www.sge.com, if they still exist.

However, make sure that you are extra careful to ensure that the column is cooled right down to room temperature and lots of clean, dry, oxygen-free gas has passed through the column before disconnecting.
The older columns get, the more oxygen-sensitive they become.

I prefer hydrogen carrier gas as it seems to give polar stationary phases a longer life, but that may be just the relative quality of the available gases here.

Bruce Hamilton

[Peggsy]

Thanks GCguy and Bruce for your comments.

GCguy we have made afew runs with standard to assess the efficiency of this column and compared to the "existing column we get coelution and poor peak shape with this unused (but 10 years stored) BPX70.


We ran plenty of carier gas (He) thru at ambient conditions before baking the column out at 240C for 60 minutes, then injected standards.

We are in the process of speaking with the supplier of this column, and so far they have offered us a 15% discount on our next purchase. Although it is a SGE column, we did not buy it from SGE, just though i netter say that!

Thanks again for your interest and advice, I'll try and remember to post the final outcome if only for interest sake.

Regards
peggsy

[HbJ]

After I've dealt with some old but unused columns I have some advice for you:

Baking out for one hour is by far not enough.
I've had a very old (about ten years) SP-2250 column from Supelco which I had to bake out for over one day until it showed a reasonable performance again.

Cutting one or two loops from the beginning and the end also helps to a certain extend.

Another question: Do you see much column bleed?

[Peggsy]

Dear HbJ

I will try your suggestions and cut a few feet off the column and bake for a longer time before re-running the std.

As for your query re: column bleed, i don't think the 10 year stored column showed excesive bleed over the run (temperature range is 170 - 220C) and increase in baseline was ~200uV, compared to ~100uV for the original column.

Following are pics from the current vs 10yo stored column, in order,
1. original column full chromatogram
2. original column, baseline zoom
3. 10yo stored column baseline zoom








Hope you can see these pics!

Regards
peggsy

[Bruce Hamilton]

Ouch. I'd guess that the stored column has unfortunately seen air and temperature simultaneously at some stage during it's life.

If you have the original certificate, you could condition the column overnight and try the CoA test, but even after only an hour of conditioning, I would have expected a reasonable column to perform better than that.

You would be best advised to try the longer conditioning ( nothing to lose ), and please ensure that you ramp the temperature up very slowly. Unlike many common stationary phases with sub-ambient lower operating temperature, this column has a minimum operating temperature of 50C.

After long-term storage, the initial conditioning transition from ambient to about 80C should be very slow ( several hours ), before ramping up to 260C for conditioning overnight.

I hope I'm wrong, but I suspect the column phase has died. Try negotiating for larger discount on a new column.

Please keep having fun,

Bruce Hamilton

[HbJ]

I think Bruce is right

Such horrible performance doesn't give much hope that the column will recover but you can try anyway.

And Bruce is also right that this column has most certainly seen higher temperatures while exposed to air.
In certain (especially polar) phases (I've seen this with PEG and FFAP) these conditions can lead to a self-sustained oxidation of the phase which is irreversible.

Try to negotiate with SGE about a reasonable discount. They're quite nice and I think they'll take care of that lost soul/column

[Peggsy]

thank you to both Bruce and HbJ, much obliged for your advice.....
i absolutely love this forum!

I will give the column a "real" conditioning treatment next week sometime (got HPLC to do this week) and get some feedback on this subject back here in the not too distant future.


Regards
peggsy