How to record a chromatogram containing two different signals? HPLC-Agilent Infinity II 1260

We would like to record one chromatogram with two different signals:

Signal A at 220nm from 0 - 7 min

Signal B at 230nm from 7 - 27 min

The substances eluating before 7min are having their maximum of absoption at 220nm and the substances from 7 to 27 min at 230nm. We need to determine a purity using the 100% method.

When recording the Signals separately OpenLab calculates a purity for each wavelength.

It doesn´t work with the following settings:

The chromatogram always records at 220nm. Without signal change, which could be verified by peaks after 7 minutes.

The function extract maximum wavelength in data analysis is not an option.

  • The first method you describe, where you change the Signal A settings at 7 minutes is what I would do.  You say it doesn't work.  What does happen?  I think you would only see 1 signal, suggesting that only data at 220nm were collected, but the signal should have changed at 7 minutes.  You should see this in the instrument status panel.  You won't see a change in the signal description in data analysis.

    A more general comment is 1nm bandwidth is unnecessarily narrow.  Even single/variable wavelength detectors don't operate with such a narrow bandwidth.


    How about you collect data with a Signal at 225 nm with a bandwidth of 14nm?  That would give you a single chromatogram, covering the range 218 - 232nm, including both wavelengths you want to collect?


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