high initial temperature

[Arne]

Hi All,

we are using a CP-Volamine column for a separation of semi-volatile analytes (BP ~ 400°C). Their elution temperature is ~280°C in gradient elution. The isothermal limit of the column is 265°C and the gradient limit 300°C.

Right now we start the gradient at 150°C and ramp to 280°C.

Do you see a problem with having the inital temperature yet higher, e.g. 225°C for the gradient elution?

The ramp rate could then be somewhat reduced to effect elution of the components ON the gradient slope rather then directly behind it.

I only ever see 40/50°C initial temps or up to 150°C for semi-volatiles applications.

Thank you!

[Consumer Products Guy]

Try it !!! Then evaluate whether better/worse/same.

Back when I was working, "gradient" was only associated with HPLC; GC used the term "temperature programming"; maybe things are different now....

[Arne]

Hi Consumer Products Guy,

Thanks for the input! I was wondering about having the column permanently exposed to an elevated temperature.

[70 eV]

You could just have a standby method at a lower temp that's constantly loaded with a run method that starts at a higher temp if you're worried about decreased column life. When the sequence is over it'll drop back to whatever method it was set to before the sequence started.