Artefact peak in RI chromatogram

Hi, 

I am working with a RI detector.(1200 agilent)

My eluant ist 800 MeOH, 100 Water, 100 0.1M ammonium acetate 

I have a problem at about 3 minutes. In some chromatograms, a peak is present but in other not. 

 

1: Blank

2: reference

3: sample 1 first preparation

4: sample 1. second preparation

 

I washed the system with IPA : no peak

I made injection of 10 blanks: no peak

10 injections of the sample: peak is present.

 

One of my hypothesis was a change in the eluant. The reinjection of the same vial over the time is leading to the same chromatogram.

Parents
  • A few ideas/thoughts/comments:

    - Can you clarify the "change in the eluent"?

    - I guess you´re running isocratic with premixed solvent, right?

    - Are you using an isocratic pump? If not, have you set up your bin/quat pump correctly?

    - 80% organic is a lot for a 100 mmol buffer. Can´t you lower the percentage or concentration?

    - Make sure you don´t overload the detector.

    - Can we see the entire method?

    - Can we see the chromatogram?

Reply
  • A few ideas/thoughts/comments:

    - Can you clarify the "change in the eluent"?

    - I guess you´re running isocratic with premixed solvent, right?

    - Are you using an isocratic pump? If not, have you set up your bin/quat pump correctly?

    - 80% organic is a lot for a 100 mmol buffer. Can´t you lower the percentage or concentration?

    - Make sure you don´t overload the detector.

    - Can we see the entire method?

    - Can we see the chromatogram?

Children
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