Optimal Needle Volume

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RMJ
RMJ
in Instrumentation and Mass Spectrometry
<p><span>Is the 30-uL needle optimal for the 2-uL loop, or is there advantage to switch to a smaller needle size?</span></p>

Answers

  • lizh
    lizh
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    Hello:

    The 15 uL needle was designed for the nanoACQUITY, because of the lower dispersion. However, the diameter is narrower and so in combination with a small loop with a small ID tubing the impact on cycle time is high. Even though you now only have 15 uL volume to pull instead of 30 uL it still takes longer as the syringe speeds need to be lower to avoid cavitation too. So I would say stick with the 30 uL. Tell me more about the application and perhaps I can recommend a compromise.

    Liz

  • UPLCMD
    UPLCMD
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    I have found that the advantage of a configuration change when using a 2uL loop is gained when you switch to a smaller sample syringe (100uL to the 50uL). You will get much better precision results during method validation if you are performing partial loop injections that are less than 1uL on the 2uL loop.

  • RMJ
    RMJ
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    Thank you very much. I will simply stick with the 30uL needle.

    The advice about the smalll syringe was something I did not think about. Fortunately I am only using partial loop injections for development work, but will use full loop, and change to a 5 uL with more dilute samples in a weaker diluent, to circumvent the precision issue.

  • lizh
    lizh
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    Glad to hear that is OK,

    Liz

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