DAD-UPLC : loss of sensibility (loss of Energy) associated with flow cell
Answers
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Hello,
did it happens that your system and DAD runs dry and lamp was still on?
Andreas
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Hello ;
* Normaly our UPLC Systems are working "all time " so eluant and DAD lamp are constantly stay on ....
F.Maquin.
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Hello,
it was a try - heard that there may be problems when cell runs dry and uv lamp is on.
But than there has to be another reason for your problem: It may be that your cell has gotten "coated" by something and the uv get's partly absorbed. This may be checked by changing cell (if you have a new one or a second cell which didn't show loss of sensibility).
Maybe you can try to purge the cell with acetic aid (60% to 100%)?
Andreas
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Hello
I agree with Andreas.
The Teflon AF flow cell conducts the light and is an integral part of the light transmission unlike stainless steel flow cells which simply contain the fluid and are usually are larger than the light path, or shaped to avoid interaction with the light path and so RI effects. The problem with standard flow cells with lens is their high volume.
Therefore, if deposits or precipitation of compounds occur on the surface of the Teflon AF flow cell will result in the light ibeing more scattered and so not totally internally reflected and light transmission drops and noise goes up. Fortunately, periodic cleaning can eliminate this and attached is a cleaning procedure that should restore your transmission. Take a look at the values for exposure times before and after cleaning.
Let us know how this goes. I would also be interested in the S/N of your detector to give guidance on the age of the flow cell.
Best regards,
Liz
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Dear all ;
* We do also what is suggested in you two documents 71500172306rA and LG flow cell Cleaning and Maintenance ... ( both our lab and SAV Waters France do this work) : we both try those procedures on three of our cells having this problems ... The energu and S/N
never recover ( even after 3-5 cleaning test)...
* Waters SAV France contact several times Waters US without clear answer ... we may think this problem is linked with the Teflon in the flow cell ...
Best Regads ;
F.Maquin.
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Then I think I would like to try the more aggressive cleaning procedure. We are pretty sure that this is less a Teflon AF issue, then that the wall surface is integral to conducting light. Have you tried the phosphoric and formic for at least 4 hours.
Liz
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Dear all ;
* Waters SAV have try since several months several procedures of cleaning incuding agressive and non agressive treatments .. ( three of our UPLC-DAD have been taken by SAV Waters France without evident results ).
May be it is times now for Waters US to redesign those UPLC-DAD cell for better reliability ???
F.Maquin.
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Hello:
Hello:
I am surprised as in all other cases we have been successful in restoring the flow cell - not to say that in some cases there have been defective flow cells. We are tracking down the specific flow cells that you ahve returned.
The other thing that interests me is your specific type of work and/or compounds. I have contacted our local Waters colleagues and we will be in touch with you directly.
However, it is very important to get this feedback.
Liz
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Dear Mrs Hodgdon ;
* As you suggested I let yoy contact your Waters colleagues (for example Mr Thierry Potin , SAV Waters France).
Thanking you in advance ;
Best Regards;
F.Maquin.
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Yes, will do and thank you for circling back,
Liz
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Following the last message .. I still wait news from this problem ???
Thanking you in advance ;
F.Maquin.
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Hello Dr. Maquin,
Waters wanted to design a flowcell that would provide total internal reflection "TIR" or as ideal to that design parameter as possible. As a result of this design effort providing these characteristics we now have the flowcells used in today's UPLC PDA's, and although slightly different, the TUV. The benefits associated with this cell are numerous. Unfortunately, it has also been recognized that there are some concerns that effect energy transmission; such as, physical interaction of the deuterium lamp to the walls of the flowcell, contaminants such as ion deposits or precipitated buffers. In some instances non specific absorption of material to the flowcell walls have occured. Suggested recoveries for the flowcell involve flushing with the mobile phase as your initial attempt; if there is still no improvement flush with 100% pure organic solution (100% ACN), if the problem persists flush with 1% formic acid then flush with water until the formic is removed or until the Ph is neutral. If the 1% formic acid fails please contact your local service rep so that they can perform a system level flush.
I hope this help
Best Regards,
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Dear Dr Dave Depasquale ;
* For your suggestions for cleaning all have been test/try by Waters France (see your Waters-France -Europe collegues they know this problem !! ) : all those attemp have failed (actually Waters France have more than 5 UPLC-DAD cells not usable and no one have solution.... The only real solution is to replace those cells by a new one ...
* So I want Waters US reinvestigatte this problem and may be improve/modify the desingn of those ULPC-DAD Cell...
Best Regards;
Dr F.Maquin.
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Hello Dr. Maquin,
Thank-you for the response. We have been in active communication with our French colleagues and we can understand your frustration. Milford is always looking to provide constant improvement upon our instrumentation and designs; in the meantime, we suggest the cleaning process that was suggested and if this is not adequate to alleviate the concern than a replacement flowcell will be necessary. In order for Milford to work with you and our French organization it is imperative that the failed flowcells be returned to Milford for failure analysis; this will allow active investigations and hopeful resolutions.
Thank-You and best regards,
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Dear all ;
As you suggested in the last mail 2 DAD cell have been send back to Waters-US for testing;evaluation ... ( done about 2 -3 months ago) : I have no news since .. Could you give me some informations on those cells ??
Waiting news;
Best Regards;
Dr F.Maquin.
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Dr. Maquin:
We did indeed receive the flow cells and evaluated them. We were able to clean them, with a DMSO containing solution. I do apologize if the information was not conveyed to you. I will ask our colleagues in France to provide an appropriate wash procedure, but the suggestion that we would favor is to flush the entire system each day using the system start-up (MassLynx) based function) for 1 hour with Acetonitrile at 1.0 mL/min. (Rather than use a mix of DMSO/Water in an off line procedure that was used to recondition your cells). Additionally, it is our intention to ask if we might use your laboratory as an evaluation site if we can provide an alternate solution as Waters is actively pursuing options to improve our flowcell performance based upon customers and field input
Happy New Year,
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From Dr Francis Maquin ;
Thank you for your reply and news from the flow cells you received from us .. May be you can ask to Waters France to give back the cells you clean ... For testing/evaluation cleaning
procedureI I am very interest to collaborate with you on this idea ... : please keep me inform for more details on the way we can wok together ..
Best Regards and happy new year to you and all your colleage in US..
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Absolutely, next week I will be talking to your field personnel and we will all stay in contact.
Liz
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I assume you mean an ACQUITY PDA not an Agilent DAD? There is a procedure to wash the flow cell with acid to regenerate the teflon coating. Contact your Waters Service engineer for the procedure. How many hours does your lamp have on it? They are gauranteed up to 2000 hours I beleive.
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* As I have no real contact (information on loss of energy associated with your DAD-UPLC I send you again an E mail for news . I have "heard" you have actually a new DAD cell .. so I suspect
what we observed one year ago is also observed with others customers...Waiting news about this new flow cell ...
Best Regards ;
Dr F.Maquin
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Hello Dr. Maquin:
Fortunately our handling protocol for the flowcells has been received favorably and has been working quite well for customers running samples that require cleaning on a frequent basis. As for news of a new flowcell that information is partially correct. The "new" flowcell has the same materials of construction as the previous ones, which also have the same pathlength & volume. However, the "new" flowcell is now eqipped with an electronic chip allowing for information such as P/N, S/N, pathlength and material type, as well as, other info to be read and then propagated to the Console page within Empower for viewing. This data is also contained within a comprehensive status report. Additionaly, this flowcell is standard equipment on our most recently released PDA which has improved thermal performance along with a baseline noise level that is the best in the industry +/-3uAU while flowing with solvent. So, along with the new features of the Flowcell and the new features of the PDA, this allows us to continue our leadership position in PDA technology.
Thanks,
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