Selection of Sample Needle for the Acquity

<p><span>I have two questions: </span></p><p></p><p><span>A) There are three types of needles listed in your parts locator for the Acquity UPLC, namely they are:</span></p><p></p><p><span>1) peek</span></p><p><span>2) FEP tubing/steel tip</span></p><p><span>3) Stainless steel</span></p><p></p><p><span>What material is FEP tubing? Other than for the difference in price (and material), what are the advantages of one over the other? Currently we have peek needle but it bends easily.</span></p><p></p><p><span>B) If the tests for characterizing the seal and needle and loop volumes pass, it there a possiblity that there still might be blockages anywhere in the sample manager?</span></p><p></p><p></p><p><span>Lotus </span></p>


  • Dear Lotus:

    The FEP is Teflon with a stainless steel tip, it is just as robust as stainless steel, but offers a less expensive alternative.

    The PEEK is not as robust as SS if it hits the sample well/vial too often, but this should be manageable with the correct settings and configuration. For example, I would recommend the SS or SS tipped needle for 384 well plates if this is your routine format, but not necessarily for vials. Can you comment on what your sample format you use most commonly? Also sometimes the pre-puncture needle is not replaced as often as it should be and becomes dull. Also check that your needle depth setting has the correct offset and calibration. What is your firmware version of the system driver?

    In chromatography anything is possible. For absolute confidence the whole suite of tests would be recommended, this includes the Needle Seal Leak Test, Weak Wash Syringe Leak Test, Sample Metering Syringe Leak Test, Strong Wash Syringe Leak Test, and Pressure Regulator Leak Test. This will determine the wetted flow path area to troubleshoot. I am guessing you see low sample pressure errors, also do not forget sample viscosity could be the root of the issue and not the Sample Manager, if your syringe speed is too high.

    Best regards,


  • Hi,

    I did replace needle once and found that the best choise would be SS with teflon tubing. SS with SS tubing is very difficult to install. The PEEk needl was originally installed but bending was an issue plus carryover for some compound like Glyphosate, I am duing environmental trace analysis.

    Hope this helps.

  • Thank you Maxim.

    The bending of the peek has been an issue for us too. I have already ordered the teflon with SS needle. Your reply is very much appreciated.