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

Question asked by davidbrown on Mar 25, 2020
Latest reply on Apr 2, 2020 by davidbrown

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?

 

thanks

David

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