Using deep 96 well plates on an LC 1290 Autosampler (G4226A)

We are using deep 2mL 96-well plates on a 1290 autosampler (G4226A), with MassHunter acquisition B08. We are using an automation platform where ~1.5 mL of eluant is collected in these plates, evaporated to dryness and then reconstituted in 50 uL of solvent. The wells are covered with a silicone closing mat and then run on the instrument. Generally this works fine with a plate with a very steep taper at the bottom of the well. We are exploring alternative plates with a different shape and are struggling to get the needle to get to the bottom of the well to sample the low volume of liquid.


The plate I am testing is an Agilent plate with an Agilent closing mat. Plate height (with mat) 46.1 mm, well depth (with mat) 43.85 mm.


With well bottom sensing on: The needle touches the bottom of the well and then moves up ~2mm (rough estimate) before sampling. Using a negative draw offset does not make the needle go lower. If I use positive offsets the needle does sample from a higher location.


With well bottom sensing off: Negative draw offsets do not get the needle closer to the bottom of the plate. Manipulating the well depth to trick the instrument to thinking the well is deeper does not make the needle go deeper into the well. I can do the reverse and trick the sampler to think the well is shallower.


On a side-note. Changes to the plate dimensions seem to only take effect after a power cycle of the autosampler, even when the changes are made to a plate that is not currently assigned to the sample tray.


I have seen the needle touch the bottom of the plate using well bottom sensing so I know the arm can get to the bottom, but how can I get the needle to sample lower? Is there a firmware/setting that prevents sampling below a certain height?




Parents Reply
  • Hi Andy,

    With bottom sensing off I tried -1.0, -1.9, -2.0, -3.0, -4.0 mm. There was no noticeable change in needle heights.

    With bottom sensing on I tried -0.5, -1.0, -1.4, -1.9, -2.0, -2.5 mm. There was no noticeable change in needle heights.

    If I put in positive offsets then I noticed tip heights change.



  • Hi David

    I'm surprised to hear that setting the needle height offset to -4.0mm makes no difference; I've seen this sort of depth hit the bottom of well plates on other samplers.  Got to be worth a call to your local Agilent support team.


  • Hi Andy,


    Thanks for your help. I have the issues raised with Agilent support, but they are struggling with reasons it is not working - lack of experience working with well plates. 

    Something that seems odd to me is that in the help menu it says there is a check box "is wellplate" in the edit wellplate panel. This apparently distinguished vial plates from well plates. There is no such check box in my edit wellplate panel. Not sure if the help menu is for an older version, or something is missing in my acquisition version.



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