Troubleshooting ghost peaks and Function field

When you are trying to figure out the source of a ghost peak in a run, what's the difference between using the following in Empower:

- Inject immediate sample (as Function in Run Samples)
- Condition column  (as Function in Run Samples)
- setting 0 ul as injection volume on a entry in the sequence table.

I figure some go past the injector and some don't?

Best Answer

  • MJSMJS
    Accepted Answer
    Inject XXX will perform an injection of course, but including the "immediate" in there changes that function to bypass the autoinjector, essentially allowing for a manual injection.  When troubleshooting, this would not make a whole lot of sense to me as you would just want to do a 0 µL injection to get the same effect without the hassle of interacting with the system.

    A 0 µL injection should go through the entire injection sequence.  There just wouldn't be any sample drawn up into the needle/sample loop.  If you select a vial with anything in it vs a water vial or even simply an empty vial, you risk contaminating the needle if the ghost peak is due to a contaminant.  I prefer to do an empty vial and a diluent/mobile phase blank to compare.

    A Condition Column will simply run through your instrument method, but won't acquire any data (although you can watch the real time plot).  It is similar to Equilibrate in that sense.  The difference is that Equilibrate sets the instrument at starting conditions and runs that way for the specified time whereas Condition Column will execute any gradient changes just like an injection (but should bypass the injector).  In chasing down a ghost peak, I could see using a Condition Column to "clean" the column without making any injections, but it sort of depends on what you think may be causing the ghost peak.  I use it most commonly just to get a system up and running prior to injections.

    I've attached the applicable Help file that describes the functions as well.
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