Acquity H-Class wash solvent

<p> Hi Everyone,</p><p></p><p>My laboratory just purchased our first UPLC, I wonder what everybody uses for needle wash and seal wash solvent? For HPLC, we usually use 50% MeOH 50% H2O in our laboratory. We also use it to wash our column and systems after sample set is finished.</p><p></p><p>Thanks!</p><p>Jianshi</p>

Answers

  • In the past I have always used 100% MeOH for the seal wash. However, using 50:50 H2O:MeOH is also quite common. So, there should be no worries there.

    For a UPLC the needle wash has been broken out into Solvent Manager 1 and Solvent Manager 2. As it was explained to me, Solvent Manager 1 is a weak needle wash and Solvent Manager 2 is a strong needle wash. As a result, I have used the sample solvent minus any acid, base, or buffer salts for Solvent Manager 1. I will generally use 100% organic solvent of what ever the Solvent Manager 1 solution is assuming that the product/api being tested is more ogranic soluble than water.

  • Hi

    The best way to look at this is to ask what each solvent's purpose is.

    For the seal wash the solvent is removing the salts or buffers that might precipitate on the plumnger, crystalize and wear the seal suface. The solvent then needs to dissolve the salts, acids, bases, additives. It also can run at different flow rates. The compatibility is only with the solvents, but for the H-Class the ability to blend four solvents means that the mobile phase can be wide ranging. I believe that 50/50 is too high a concentration for this purpose. More aqueous, with some organic would make a better re-solvent. However, this is a risky statement as it assumes your work is 100% reversed phase, but if your methods are normal phase or HILIC or ion exchange, clearly this would be inappropriate.

    The needlewash has a very different job, it is re-solvating any precipitated sample and sample diluent on the needle surface and preventing carryover. Its choice should be to dissolve the sample and be compatible with the sample diluent and therefore in this sense should be closely related to the sample diluent. Needlewashn is more specific to the sample and the actual analysis. Samples can have wide solubilities and so this should be more organic, as sample components elute across the range of a gradint analysis. If the analysis is isocratic, than a similar solvent to the mobile phase would be appopriate. It is often necessary to adjus between sample sets, but not in all cases. Clearly a sample soluble in 100% methanol and a sample soluble in 10% methanol would be better served by different needlewashes. The H-Class sample manager needlewash is in contact with the external surface of the needle and des not have to match the mobile phase, it only has to ensure the sample solubility.

    For exisitng and transfered methods, what has worked in the past is a good place to start. However, in general, a good needlewash is not the same solvent mix as a good seal wash.

    Hope this helps

    Liz

  • Hello again

    I just answered assuming that you have an ACQUITY UPLC H-Class, and an FTN type injector. Can you confirm, as it may be that your system is the priginal ACQUITY. The easiest way to tell is to list the labels on te pump and the injector

    Best regards,

    LIz

  • Thanks very much, very helpful information!

  • Yes, my system is H-Class with FTN sample manager

  • Thanks Liz! Very detailed and helpful tips.

    Best

    Jianshi

  • Nicely put.  I agree with this post completely.  Oh how often have I had to explain this to new analysts in our labs.

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