If there are bacteria that can live in 100% ACN (a.k.a. methyl cyanide), I would not concern yourself with them. It's the bacteria/algae that grows in your aqueous mobile phase(s) that is your enemy.
Bacteria grow in your aqueous mobile phase over time. Then through the chromatographic process the bacteria-containing solution is pumped through your LC system, thus contaminating anything that comes in contact with it (e.g., mobile phase sinker, tubing, column, detector, etc).
As with many things in life, it is easier to prevent something than it is to cure it. Good laboratory practices are the key: use high quality water and solvents; filter your aqueous mobile phase and samples; change your aqueous mobile phase daily (or better yet add some organic modifier (5-10%) to your aqueous mobile phase); never 'top-off' your aqueous mobile phase, instead dispose of remaining mobile phase and prepare fresh & clean mobile phase; pre-mix your isocratic mobile phase - do not use the LC system to do the mixing; ensure your water purification system is well maintained; maintain your LC system; etc. Just follow good lab practices, nothing radical.
Contact your local Waters support person. He/she are very knowledgeable regarding the care of your ACQUITY UPLC system(s). If you are experincing bacterial growth issues in your mobile phase, they can provide you with guidance as well as recommend a decontamination procedure.
Some good references:
Sorry~ it was my typo & mistake. It was 70% IPA which bacteria become resistant, not 100% ACN.We've been trying waters guard column, washing the system, changing to fresh buffers and wash solutions. However, BEH200 Columns last 20 injection to 400 maximum;(
So, we need to figure out how to prevent & minimize these small enemies!
What is the reason to not use Autoblend system? I heard some of us are using that method...
Thanks a gain,
Apologies for the confusion. There is no reason not to use AUTOBLEND. It is a fantastic and enabling technology.
My 'pre-mix' suggestion was for isocratic separations so that you are mixing/adding your organic modifier (e.g., ACN, MeOH, IPA, etc) and ending up with a more bacteriostatic solution (vs. a 100% aqueous solution). Bacterial growth in 70% IPA? Really? I would not not worry about such a solution in LC (assuming a 'normal' time period for mobile phase use & replacement) unless the water that was/is used to prepare the 70% IPA solution already had bacteria in it.
Most people experience ZERO problems with bacterial growth in their LC systems. However, once it happens you must be vigilant in its removal. For that reason I ask that you please contact your local Waters support person. They can help. If you are not sure who that is please contact me directly and I will find out for you.