Double Peak

[kermit]

Hi ! I am new here
I am a student currently working on hplc separation
The problem was the separation was fine a couple of weeks ago


However, when I try running the separation last week, all the peaks began showing a double peak at the tailing end




I have tried preparing fresh standards and mobile phases, but it doesn't seem to help though

Any advice is appreciated. Thanks

[Friederike]

Hi kermit,

looks like the inlet of your column is contaminated/partly clogged.
If you use a guard column: replace it (if not: consider its use).
Try backflush the column. Maybe your column allows for the change of the inlet frit. I also would advise you to re-think your sample preparation.

Good luck

[Consumer Products Guy]

I agree with Friederike's post. Try a new column, see if that reproduces the good separation on the standard or sample, just to make sure the instrument is fine. Most column suppliers have a process to clean out columns, might include backflushing, stronger solvents, check with supplier.

You may need to inject less volume/material, clean up your samples more prior to injection, stuff like that. Your initial chromatography looks nice.

[Ron]

Is the instrument used regularly, or does it sit unused for several days at a time? If you are using buffers and the instrument sits for several days or weeks without being used you can have precipitation of buffer in the system and that can cause problems.

[Dr-mostafa_omar]

I would like to ask you if u washed the column after the last use that was Ok? cuz if your mobile phase contains a buffer then most probabaly there might be some distortion to the stationary phase....also i think that even if the instrument is used regularly, flushing the whole system after finishing your runs prevents the precepitation of any salts in the whole system's tubing.

[tom jupille]

We have a mini-seminar on our web site that addresses your problem exactly:
http://www.lcresources.com/more_resourc ... hp?f=3&t=3

You will have to register (free) to view it.