Improving method cycle times

mattychem
mattychem
in Instrumentation and Mass Spectrometry
<p>I am using a UPLC system fitted with a binary pump, sample manager, column manager and sample organizer.  In some cases our method cycle times are nearly double our method run times.  Can anyone provide tricks for reducing the time required for injection?  Also, what is the fastest injection turnaround I can expect with this system (e.g. 30 sec)? </p>

Answers

  • lizh
    lizh

    Hello:

    What is the aim of the analysis, what is the cycle time that you are looking for and why and what are your experimental goals, is speed the most important to you? These will determine how best to optimize the method settings.

    For MassLynx, about 22 seconds is an average best, Empower can do better. Can you provide your method, including column dimension, flow rates, detector settings, needlewash volumes, the data software that you are using, as well as the ACQUITY UPLC Driver version as perfromance in cycle time depends entirely on the instruments and how they are configured.

    It also depends on the method as for example injection volumes. Obviously, a 50 uL injection will not be as fast as a 5 uL volume. In Full Loop injections can take time while the loop is being overfilled. Have you enabled "Load Ahead"? With a column manager the method will wait until the column temperature is stabilized. Hence my request for a summary of the conditions and setting used.

    Many TX

  • mattychem
    mattychem

    Elizabeth,

    Speed is most important.  I am using MassLynx SCN 714.  No column (FIA).  Flow rate is flexible (0.1-0.5 mL/min), TQD, standard needle wash volumes currently, Targetlynx processing, not sure on the Driver.

    Injection volume flexible (1-5 uL), 10 uL loop currently, Load ahead is enabled with PLNO.

    Thank you.

  • lizh
    lizh

    Apologies that it has taken me so long to get back to you, but to optimize a method, all the parameters are important to optimize. O if you will forgive the time, here is an outline of the items that influence cycle time and can be optimized, within acceptance.

    Firstly, based upon what you have noted, first think is to get the flow rate as high as possible, is there any reason why you are not going higher than 0.5 mL/min?

    Here are things to consider:

    System Configuration and Data System variability - Empower, MassLynx, Analyst have different overheads, Empower being the best. Obviously other factors, such as CPU speed and whether data processing time is included, which I will assume that you have optimized if you can. Also, if a PDA is included in the system configured, ensure that data rate is set appropriately, exposure time can increase when data rate is not set high, for UV absorbing mobile phases e.g. TFA etc.).

    Run time dependency - Sample Manager configuration, make sure that the needle wash volumes and Solvent are minimized/optimized  (50/50 MeOH is v. viscous). This is true of sample diluent, (avoid DMSO if you can), set the highest aspiration speed consistent with injection reproducibility. Injection Mode makes a difference, PLPA being fastest, (try varying this and see if this helps) or if need to use PLNO, reduce the pre-injection volume to reduce the time. Use the “Load Ahead” option. Speed I influenced by Injection Volume. But smaller loops have smaller ID’s so aspiration is slower, your 10 µL loop is a good intermediate choice for making a 1 or 2 µL injection. Finally, the Needle ID, use a 30 µL needle.

    Hope that this helps

    BR

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