Peak area difference

Hi All,

I am looking for information that would explain a significant difference in peak areas between G1321B (Agilent 1260 Infinity) and G7121B (Agilent 1260 Infinity II) FLDs. The same method and samples are being analyzed on both HPLCs, LU response is higher on G7121B (0.35 LU) than that on G1321B (0.05 LU), but peak areas are significantly smaller on G7121B (e.g., 2 uV*sec.) versus G1321B (e.g., 294344 uV*sec). Initially it was thought that this was caused by an analog output range setting of 0.1V versus 1V, however, it was not the case since G7121B had been verified as being set at 1V. What causes this peak area difference?

Maybe it is still due to the analog output range that may have a different setting in Empower configuration? Empower configuration will override settings on the instrument, if they're not a part of the instrument method. Analog voltage range was a part of the instrument method on G1321A (Agilent 1100), but not anymore on Agilent 1260s. In any case, what does this setting do? How does it impact the peak area?

Many Thanks for your help!

  • Hello...

    This is from one of the service notes:

    In order to achieve identical results for the analog out on G7121A/B FLDs than on G1321A/B/C FLDs, the attenuation has to be increased by 1.

    If an existing method from G1321A/B/C FLDs is using an attenuation setting of 9, the value needs to be set to 10 on G7121A/B FLDs. However, the attenuation AAT1 cannot be entered directly in Chemstation, but the advanced method setting "Analog Output/Attenuation" of 100 LU in Chemstation corresponds to an AAT1 value of 9, so in order to achieve identical results as on G1321A/B/C, Attenuation 200 LU needs to be set.

  • Hi jhagel,

    Thank you so much for this info and your prompt response to my question!

    Is the attenuation increase by 1 (or by 100 LU) still applicable to the Empower acquisition since data are not acquired via analog out, but rather via LAN in Empower?

    Is there any technical document that would explain the difference between G1321A/B/C and G7121A/B FLDs? Comparing technical specifications for both, these FLDs are identical. 

    We have dual detectors installed (VWD and FLD) on both, Agilent 1260 Infinity and Infinity II HPLCs. So, we only see this phenomena of peak area difference for FLDs only. The VWDs G7114A and G1314F generate the same peak areas with a 1000 mAU attenuation on both. So, is this attenuation difference only applicable to FLDs?

    Many Thanks for your help!

  • The attenuation is if you are using the analog cables out the back.  

    Here is the user manual: Agilent InfinityLab LC Series 1260 Infinity II Fluorescence Detectors User Manual

    pages 125-129 explain how to adjust for scaling. I'm not sure about Empower

  • Thank you so much for your response!

    We are not using the analog cables, so attenuation is not the issue.

    I've got a response to my query from Waters, and was told that there's an Empower software defect, which is fixed in ICF 3.1 version.

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