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I-Class SM-FL: "Sample fluidics over-pressure" during characterization and "sample-pressure low" at injection - WKB7433

Article number: 7433

SYMPTOMS

  • Low pressure followed by high sample pressure failure when resetting the Sample Manager from console.
    • Low pressure failure occurs when "emptying the sample syringe" after washes performed and in preparation for sample draw/aspiration. Intermittent every 40 injections or so. Progressively worsened to an occurrence every 2-3 runs.
    Replacement sample needle, inject valve, sample loop resolves issue for short period of time.
    • Performance maintenance and operations successful for ~4,000 injections, and then intermittent failures occur.
    Reproduce the low sample pressure error when making injections. Reproduce the high sample pressure error when calibrating the loop and needle volumes.

ENVIRONMENT

  • ACQUITY I-Class Sample Manager - Fixed Loop (SM-FL).
    • 384 shallow well plates with water covers with 20-ul total sample volumes. Needle placement programmed to 0.8-mm needle depth (from the bottom of the well) to meet residual volume and make 10-ul injections. Chemists centrifuge the plates to spin down the sample protein, but over time. Precipitate formed out of solution.

CAUSE

  • Needle placement programmed to 0.6 mm-and 0.8-mm (needle depth from bottom) much lower than specified or as recommended.
    • Lowering the needle placement risk elevates risk of introducing debris or precipitate into the fluidics lines. Suspect sample precipitating in the exchange of strong and weak washes in needle, loop, inject valve, and waste lines.

FIX or WORKAROUND

  • Follow recommendation for 384 well plates:
    • Sample Manager Fixed Loop using 384 well plate (Default Needle Placement of 2 mm has a residual sample volume of 15 ul in order to make an injection.
      1. Set the needle placement to "automatic" in the instrument/inlet method. Use minimum 25 ul of sample to reduce risk precipitates/debris clogging Sample Manager fluidics.

ADDITIONAL INFORMATION

 Performance maintenance:

  • Consider more frequent PM schedule running application. Replace sample needle, sample loop, and inject valve as necessary.

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