Strange split peak problem

[shoom]

I have just changed a column in a like for like swap ( db-wax) due to the previous column apparently coming to the end of its life. Since then new column has been installed and conditioned. When doing analysis the early eluting peaks give nice sharp peaks but the late eluters just give a spiky mess of split peaks that the ms says are the same analyte. Why would this happen? the early eluters seem fine but the late ones not?

I have changed all the easy stuff so far, septum, liner and no other setting have been changed on the GC.

Thanks for any help and advice offered in advance.

[chromatographer1]

check the installation and the condition of the ends of the column.

You have a misinstallation of the column.

best wishes,

Rod

[Peter Apps]

I addition to what Rod said, make sure that the column is not touching the oven wall.

Peter

[shoom]

Thanks.

I have checked the ends of the column and all seemed fine. I am going to reinstall both ends again and check for touching as suggested.

Thanks again.

[shoom]

Right, done all that, reinstalled column. checked for leaks, none. But when I inject a standard the solvent appears as expected no sign of the analyte anywhere ( Methyl stearate). I have tried injecting the same sample on a different GC with a different column and I get a completely reasonable result.

I am completely flumoxed by this?

Any help please?

Thanks

Shoom.

[chromatographer1]

Shoom,

Clearly describe each column and the temperatures (injector, oven, detector, + amount of analyte) you are using and it may become clear why you are having the loss of analyte you are experiencing.

Some things in chromatography are not rocket science.

best wishes,

Rod

[Peter Apps]

Check that the oven is actually running its temperature programme.

Peter

[Bigbear]

Could be a bad column. Just because it's new is meaningless.

[cleh]

May want to make sure the transfer line temp is correct. May have been unintentionally changed and saved in the method.

[shoom]

Thanks all, will try suggestions.