Chromatography Forum

I recently installed a new column in our gc/ms agilent.
The column is rtx-1ms (30m, 0.32 mm, 0.5 um).
The oven program is 100C for 1 min then 20C/min to 300C for 7 min (total run 18 min)
When it is reach around 10 min the baseline starts to bleed!! although the separation is occured but staionary phase ions always appearing.

I changed the septum, liner, reinstall the column at injector port but no sucssedense.

any hints?

First of all: all columns bleed some, some just more than others. If you magnify enough, you will always see some bleed. One tries to have the analyte signal considerably more than the noise or bleed. What is your split ratio and what are your concentrations? Are you getting enough analyte on the column?

If your carrier purification system is not removing oxygen to a low enough level you could be destroying your column.

That would be my guess.

Rodney George
consultant

che313,

You have a leak detector already installed. What is your 28 and 32 doing, how big are they? Any other odd ions at idle?

Best regards.