Dried column

[Camisotro]

One of our columns (Zorbax Eclipse Plus C18) was left on the LCMS with no cap on its output end during maintenance, and this went unnoticed at the end of the day due to other unexpected facility issues that day. The last thing I had in the column was 80% or 90% methanol/water, no additive.

It probably spent a good 18 hours uncapped. I'm flowing 60% methanol/water through it now even though I won't be using it for a while, as I wanted to ensure it stays hydrated. Should I be concerned of possible irreversible effects if it was left open that long?

[Mr.Brown]

columns that have completely dried usually show some deterioration

How ever back at the university some people always forgot to cap the columns when they switched them.

I usually ran a gradient from 10% MeOH to 100% MeOH and back
which most of the time worked
for storage I filled it with 80% MeOH (or ACN)

However its always a good idea to have a spare column near by

[Camisotro]

Our usual gradient is almost that long, so next time we have a run to do I'll just make sure to inject a few QC standards and check for RT drift.

[James_Ball]

I have had columns that were left uncapped for longer times that were just fine. I found one that was switched in and out often and the guy we had running the instrument at the time had mistaken two finger tight PEEK nuts for column plugs. He always put them in, just didn't know they had holes in them instead of being solid That column has been around and working longer than any others strangely.

[Alp]

I think columns made over the last 10-15 are much less susceptible to problems from drying out. I do not think you will have any problem.
Run some test samples, verify retention times, peak shape, peak intensity...

Alp

[Klaus I.]

It probably spent a good 18 hours uncapped. I'm flowing 60% methanol/water through it now even though I won't be using it for a while, as I wanted to ensure it stays hydrated. Should I be concerned of possible irreversible effects if it was left open that long?

No, there should be no problem to store a modern analytical column in dry state (18h uncapped are surely of no importance). Problems can occur when you store a C8 column in a methanol/water mixture. Also if this phenomena may be negligible for C18 columns, i prefer to store columns in 100 % acetonitrile. If you are afraid of acetonitrile-polymerization you can add 10 % of water to the acetonitrile.

[Camisotro]

No, there should be no problem to store a modern analytical column in dry state (18h uncapped are surely of no importance). Problems can occur when you store a C8 column in a methanol/water mixture. Also if this phenomena may be negligible for C18 columns, i prefer to store columns in 100 % acetonitrile. If you are afraid of acetonitrile-polymerization you can add 10 % of water to the acetonitrile.

I was not aware of any issue with methanol-water storage. We do not regularly keep acetonitrile as one of the bottles on the instrument as it is not in any of our routine methods right now. Could you explain what the problem is?

[Klaus I.]

No, there should be no problem to store a modern analytical column in dry state (18h uncapped are surely of no importance). Problems can occur when you store a C8 column in a methanol/water mixture. Also if this phenomena may be negligible for C18 columns, i prefer to store columns in 100 % acetonitrile. If you are afraid of acetonitrile-polymerization you can add 10 % of water to the acetonitrile.

I was not aware of any issue with methanol-water storage. We do not regularly keep acetonitrile as one of the bottles on the instrument as it is not in any of our routine methods right now. Could you explain what the problem is?

The methanol/water mixture hydrolyze the silica gel, particularly when the surface is not protected e.g. C8-column. Some years ago colleagues have stored all columns in water/methanol (v/v = 1/1) and have killed every C8 column during storage time (3 – 6 month).
I am not sure if all C18 columns have survived this treatment, but the surface of the silica gel is better protected.

I think you can also use 100% methanol as storage solution for almost all RP-columns.

[Camisotro]

The methanol/water mixture hydrolyze the silica gel, particularly when the surface is not protected e.g. C8-column. Some years ago colleagues have stored all columns in water/methanol (v/v = 1/1) and have killed every C8 column during storage time (3 – 6 month).
I am not sure if all C18 columns have survived this treatment, but the surface of the silica gel is better protected.

I think you can also use 100% methanol as storage solution for almost all RP-columns.

The Agilent techs told me 50/50 was not good for storage, but said that 70-80% MeOH in water is sufficient to keep it in good shape.