Waters uBondapak C18 Column Problems

[Uwe Neue]

Guys, Please let us not spread unfounded rumors around in public! MicroBondapak C18 columns are stable way beyond 400 atm or 6000 PSI. Pressure is not the problem, JM, and irregular silica does not compress.

I stick exactly with my recommendation from before: try to equilibrate it for an extended time period with the ion-pair reagent. If it recoveres, be happy. If it does not, you have no choice but to buy a new one, but now I recommend to never put it into 100% organic storage, but keep it in the mobile phase. You will have many happy runs.

[Uwe Neue]

BTW - I forgot to ask if you had this high pressure already up front or only after some use? Or did it happen after your storage in methanol?

[lstyger]

I've always had this high pressure just from originally running the mobile phase and its been pretty much the same even with storing in methanol- its gotten slightly higher, but not by a significant amount.

[Uwe Neue]

Well, these two things (high backpressure and low performance) may or may not be related. The column is shipped in an organic solvent. Thus when there is something in your mobile phase upon start-up that could precipitate that could be a reason for the higher pressure.

If the added equilibration does not fix the column performance, I think it is time to get a new one.

[JM]

Uwe my observations about microbondapack are based on actual experience with these columns and not a rumor ,

Change the column to spherical silica ( may be inertsil or YMC ) and see the difference in performance and life.

JM

[Uwe Neue]

JM: I have nearly 30 years experience with this product, and I am familiar with the details how it is made. I am also familar with studies that have tested the mechanical stability of different silicas, and under what circumstances they fail, what the nature of the failure is and related things. Compression from repeated use is not on the list for this column, and your statement that 230 atm is too much is not on the list either.