Classic Acquity - common challenges and resolutions

<p> Having used classic binary Acquity for more than 5 years now, I can categorize the most common challenges encountered as follows :</p><p></p><p>1. Carryover - Variables include injection mode, piercing and sample needle, wash solvent type, composition and volumes, loop fitting, wash station, injector POD, air sensor tube etc.) </p><p>2. Adsorption (in cases when not observed in HPLC) - Variables include type of needle material, loop, adsorption in Tefzel tubing in bubble sensor etc.</p><p>3. Low recovery of API from formulations (tablets, capsules- assuming HPLC recovery is fine)- Variables include sample viscosity (not something that can be changed), injection mode, draw speed, overfill factor, needle material, sample solubility in dileunt etc.</p><p>4. Non-linearity at low end of concentration (Response factor quite different compared to higher conc, assuming HPLC linear range is acceptable).</p><p>5. Variable precision for standards. Variables include injection mode as one of the factors</p><p></p><p>Can Waters pull together a document to guide the UPLC community stepwise on how to address the above 5 areas, using binary Acquity UPLC.</p>

Answers

  • Hello HPLC UPLC:

    I would be interested in other responses from the rest of the eCommunity, but generalizing, it seems to that the challenges that have been encountered have been making the UPLC method completely equivalent to the HPLC method.  This can prove difficult for some examples, if the limitations/limits of the original HPLC method are not taken into account. Or rather limitations that were not significant for HPLC become more important in UPLC. There are other critical factors to consider for perfecting method transfer:

    • The UPLC system characteristics of low dispersion/bandspread and low dwell volume
    • The design differences between a low dispersion ACQUITY UPLC system and the typical higher volume HPLC system.

    Do you agree?

    Do you have some suggestion in mind for the guide, a troubleshooting tree? Traditionally, Waters has addressed issues like this with training courses. Another option might be a web based tutorial. Waters has also provided pod casts as another alternative. I am not sure that all of these issues arise in all cases, but I will wait to see what the response from the rest of the eCommunity is. I am worried that a tool will be too complex and/or less relevant

    My own experience has been that some transfer examples where the nature of the analytes are diverse can be tricky and that the difference that the system design can enhance this. Generally, the lower dispersion UPLC system can lead to solubility issues which are not encountered in HPLC and therefore unexpected.

    It was from feedback such as this in mind, that the ACQUITY UPLC H-Class system was designed. The Autoinjector in particular is more HPLC–like. It is a flow-through-needle design and so has advantages (1) The entire contents of the needle are transferred to the column and (2) the flow paths of the FTN Sample Manager experience the entire gradient, which also ensures that the sample constituents are transferred to the column. Waters believes that customers will trade this lack of complexity over some of the performance characteristics of the Fixed Loop version. This was the entire design premise behind H-Class to make a UPLC system with HPLC characteristics, to enable more straightforward transfers as the inherent system design differences are essentially eliminated and method transfer can be less complex.

    What does everyone else think?

  • Hello Liz,

    Thank you for the note. A generic decision tree guide will be appropriate way to address some of these challenges. Also, to clarify, typically people will develop UPLC methods as the default method development practice these days,to take advantage of the UPLC benefits. The method transfer aspect is absent for companies which may decide that any new project should be using UPLC instead of HPLC as the first choice. So, the challenges like carryover, recovery, poor linearity at low conc needs to be tackled from UPLC perspective, with no reference HPLC results. If however, the same issue persists with both std and H-Class Acquity, then it may be worth looking into HPLC (i.e- translate to HPLC) and see if it also occurs in HPLC. Also, the othe aspect is many companies have invested already in std binary Acquity over the past 5 years or so, and will continue to use those systems.

    My feeling is going with simple decision tree /flow chart to take the user through the troubleshooting in stepwise manner will be useful.

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