Chromatography Forum

Hello,
i´ve a problem with the base line, from one day to another the base line up from the original one and i dont know what is the problem....i turned the temperature up to clean it but its still up the base line when i run solvent... i need help i dont know where is the problem.


Thank you.

Hi there, I´ll recommend to clean the liner and check if the split ratio is the same in both days. Other option is that damage of stationary phase of the column and it need to be replaced, but since the results are from one day to another probably is the last option.

Have a great day and let know the result.

The erratic baseline at max temperature on the good run is also troubling. You may have an air leak near the inlet side of the system that is allowing in air which is quickly degrading the column. The rhythmic nature of the baseline could be from the electronic pressure control trying to maintain the higher pressure at the end of the run to compensate for a small leak.

i´d tryed changing the liner but still wrong the baseline, i'd changed the column, low a little bit but still up the baseline.
It could be a leak? like you said, the pressure valve is broken but the tecnitian said that we can still work...can i check the leak? where can i find it.... the moisture trap and the oxygen trap are empty, i have to change it...it could be that problem?
i have two chromathographers one is new and the other is an old Varian, but the base line in both are wrong at the end of the run...what could be the problem?

You must have oxygen and moisture scrubbers that are still working, because oxygen and moisture in the carrier gas will damage the stationary phase and cause the rising baseline that you see. If there is water and oxygen in the carrier gas baking the column will destroy it all the quicker. To check for leaks you need an electronic leak seeker.

Peter

thank you all, i will change the traps and see what happen. tell you later how its goes..