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Thermo Fisher Scientific

AS-AP Poor RSD or inconsistent peak areas


One or more of the following is occurring:

  • System is not reproducible and is not reliable
  • Injections are varying from sample to sample
  • Poor RSD


AS-AP Autosampler


  1. The placement of the 2 green waste lines are important to maintain consistent area response as an incorrect waste lines can siphon liquid causing poor area reproducibility. See the AS-AP Operator's Manual.
    reproducibility - image 01.png
  2. Be sure the sample loop, syringe size and buffer loop used on your hardware matches what’s in the configuration.  Below are the default settings:

    reproducibility - image 02.png
  3. See slide below for more causes of poor RSD:
    reproducibility - image 03.png
    1. You can change the puncture offset of the sampler in the “commands” 

      reproducibility - image 04.png
    2. You must set the command level to “expert” by right clicking in the left pane in the red circle area and setting to “expert”

      reproducibility - image 05.png
  4. Be sure your 250ul syringe on the ASAP is fully primed with no air bubbles. Any air bubbles will cause poor RSD.  It a good idea to run these 3 action items before every sequence to ensure the sampler is fully primed:

    reproducibility - image 06.png
  5. If any air bubbles are still present, remove the syringe, prime by hand, and reconnect the syringe.

  6. If reproducibility issues persist, replace the suppressor. 


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