How do a lose this ghost peak?

[efirth]

Someone please help! We are running sugar, ethanol and organic acid analysis on a Rezex RHM (H+) column using a waters alliance 2695 with RI and UV detection with 5mM Sulphuric MP. We have been running this analyses problem free for some time now, until a new Waters system was installed(I say new, it is a loan system from Waters and I do not know what it was used for previously). On the new system, a ghost peak appears right on the tail of the ethanol peak (typical!!) I have tried purging the needle wash and injector wash. I have changed the needle/injector wash to show that MeOH is not the problem. I have run counltess blanks and samples and the peak does not diminish at all. I have also performed a strange Pagan ritual and this has not helped either. Anyone got any ideas?

[danko]

Hi Elliot,

Are you using both systems (the old and the new) simultaneously and if so, try shifting columns.

Best Regards

[efirth]

Good point, Danko. I'll give that a try.
Thanks. Don't think it will help, but will let you know.

[Noser222]

can you do a manual injection?

[efirth]

Manual injection not possible. Going to flush the whole thing with 30% phosphoric acid. Lets see if this peak can defy me know! Any other suggestions still welcome.

[AdrianF]

Glad to see you are enjoying yourself in your new job!
Does the ghost peak appear in the UV or RI trace or both.

[efirth]

Is that the learned Mr. Fairhead of a certain pharma co in Eastbourne? I hope you are well and that Cyndie is leaving you alone! The peak is in the RI trace only and it still appears with a zero volume injection (ie. Injector does not enter the stream). I have a chap from Waters in today to pacivate the system (better make sure I remove the column!) Think that this should do the trick.

[AdrianF]

Thats me. After I had written I realised it must be RI as etanol has no response in UV. It looks as if its a contaminated system.

Nice you are able to get your teeth into an interesting problem.

All the best - Happy Christmas from Eastbourne

[efirth]

Merry christmas to you too. Try to ensure that Silvester doesn't slack off and that Johnson is quiet occassionally! Ha ha!

[efirth]

Just to complete this topic......

A full system flush with 30% phosphoric acid did not do the trick!! It seems that the high pressure inlet valve was the offending article as, once this was replaced, the ghost peak was no more. About time!