Chromatography Forum

Dear colleagues,

I have some issue with baseline. While temperature program is isothermal I observe increasing baseline. When the ramps starts baseline goes down and it is the same until run ends. Here you can see it on this picture. Have you any ideas what could I do to prevent baseline increasing at the begining of the run?

The temperature is 60°C until 4.5 minutes. Maximum temperature is 260°C. Blue line is from ECD and red one from FPD.

Check for an air leak, it could be drawing in a little air at the low oven temperature then sealing once the temperature increases. You may have a cracked ferrule either at inlet to column or inlet to detector.

Is this an Agilent system? Initial baseline seems really high for a uECD, and even more so for ECD. Do you have a blank plug to check detector without the column?

Maybe oven ramp is chocking off column flow. Have you done any inlet maintenance, septa or liner?