Chromatography Forum

Do anyone have experience with molecular seives column? I have a ResteK 5A one. It worked properly three years ago, but now I do not see any peaks. I checked TCD, it is OK. I decided to regenerate the column using T=200C for 2 hours. It did not help. Maybe I have damaged it using this procedure. What is the max temperature for Mol seive 5A column? I cannot find this parameter.

MS5A is this a packed or capillary column?

You should see something elute. Even if the pores were completely blocked gases would elute around the particles.

I suspect a crack in your capillary column or a leaking connection if it is a packed column.

That or the column is completely blocked. Did you flow check?

mole sieve is damaged by temperature if water is present in the pores. A chemical reaction takes place. If dry you can heat the packing to 400C. But again, if oxygen is present, chemistry can take place.

Usually condition the column at the highest flow rate possible at a temperature below 150C and then two degrees per hour to 200C. Then slow decrease the column flow to normal rates. Heating higher than this will gain you about 10% more separation but increases the likelihood of chemical damage enormously. Why bother? Damage is determined by tailing of the gas peaks. A good column has little or no tailing. A damaged column can have a lot.

best wishes,

Rod

Rod,
Thank you very much