Xbridge 2.5um, its brilliant.
Answers
-
Hello, I read and replied to your previous post in about 1.7 um BEH column lifetimes. I also spoke with Pat Boyce at length. I must admit, this was one of only a couple times where I have ever seen this in my 5+ years of managing the Waters UPLC column family. In both cases, high pH, high temperatures and high pressures were present. I can only attempt to explain why it is happening.
When you combine elevated temperatures with elevated (UPLC) pressures and elevated pH, you can/will observe shorter column lifetime. It's a chemical, not a physical/mechanical, phenomenon. I do mention that in the . By the way, what are you injecting (sample & solvent)? What is the maximum pressure reached in your ballistic gradient method and could you please post your gradient profile?
I am glad to hear that you are enjoying longer column lifetimes with 2.5 um XBridge BEH columns. As you know, this is EXACTLY the same particle & chemistry as corresponding ACQUITY BEH columns: same particle substrate; same bonding; same endcapping; same synthesis location/people; same packing location/people. The only difference is the particle size and resulting pressures they generate.
By choosing a larger particle that requires HPLC pressure constraints, you are removing one of the three parameters that can shorten column lifetimes (pressure). If you did the same with the 1.7 um BEH particle, you'd see longer lifetimes as well. I have many long lifetime examples with one achieving more than 70000 injections on a single UPLC column.
I equate this driving fast on a winding road on a dark, rainy night. If you remove one or more of the three parameters (speed, darkness and/or rain) driving on the winding road is easy. Combine all three and you are tempting fate.
Regarding your marketing question, the 2.5 um XBridge particle columns are marketed as part of the XBridge HPLC column family that consists of 2.5, 3.5, 5 and 10 um particle sizes. The 2.5 um particle size is popular with people who wish to achieve fast separations but it does generate quite a bit of backpressure when you consider most HPLC systems' pressure limitations. Because it is the larger particle analog of the 1.7 um BEH particle, HPLC<> UPLC transition is quite easy.
I'm not sure if this helps any but I just want to make sure that you (and others) are aware that XBridge and ACQUITY BEH are based on the same BEH particle technology. The only differences are the particle sizes and maximum suggested operating pressures.
--Doug
0 -
Hi Doug,
Thanks for the reply. I am indeed aware that XBridge and BEH are exactly the same which is why I was so dissappointed in the lifetimes we were getting from the BEH columns. We have been using XBridge 5um columns on our HPLC systems running equivalent methods for several years and these columns do seem to be quite indestructable and I (perhaps naively) expected to see a similar level of performance from BEH, with the added bonus of much faster run times and/or much better resolution. We have opened a number of the failed BEH columns and the large void is clear to see so we are definately dissolving the packaging!
We did try reducing the pressure and temperature of our methods (from 11,000psi to 8,000psi and from 40°C to 30°C) and we changed from pH10 buffer to 0.1% aq ammonia but it didn't seem to make any difference to the lifetimes of BEH which is why we've started this alternative column trial.
Our gradient profile is 98% aqueous to 98% acetonitrile in 0.8min, hold at 98% acetonitrile until 1.2min. We're running at 0.8ml/min.
Our samples are a whole variety of different things from reaction mixtures to clean final products, our system runs as a high throughput machine which supports around 100 chemists so the amount and variety of samples it handles is quite large. The samples are all dissolved in methanol, acetonitrile, water or DMSO or any combination of these.
I've posted this on the forum as I'm so surprised that the XBridge 2.5um and the BEH 1.7um materials seem to behave so differently on our systems as far as lifetimes goes, especially as they are exactly the same stuff!
I'm sure I'm not the only person running at high pH and thought it would be good to share this info around as I wasn't aware of the 2.5um material until my sales rep mentioned it, thanks Terry!!
I was also wondering if anyone else had come across the same limitation of BEH at high pH...
Jo
0 -
Hi Jo,
I'm not as convinced that it is high pH alone since virtually every UPLC separation developed in the columns support labs since 2004 utilize high pH and I've not encountered any high pH lifetime issues. As I look at the description of your method, I think that it is more than just pH and max pressure. Perhaps the rapid change in pressure that you are subjecting the column to during your ballistic gradient, in combination with elevated pH and temperature may be accelerating the chemical dissolution of the BEH substrate.
What is the delta pressure for your method? In other words, during your gradient what is your minumum pressure and maximum pressure? What is this pressure change after you inject DMSO and how much are you injecting?
Like you, I too, hope that others chime in with their experience with UPLC column lifetimes at high pH. Of the few UPLC columns that eventually do fail, the cause is usually plugging, never voiding. At Waters we've had excellent luck with running BEH-based UPLC and HPLC columns at high pH. If we didn't, in 2005 we'd have never made the HPLC column version (XBridge) of the BEH columns.
Thanks for sharing your experience,
--Doug
0 -
We have traditionaly ( several years) used xbridge at pH 10 with ACN, MeOH, or both as the organic . I have always been amazed at how well xbridge columns have held up. We now have several variations of this theme with UPLCs and aquity beh C18 with no problems. The most extreme conditions is 85C, 10mM ammonium acetate buffer, 0 -90% ACN and max pressure of ~10k psi. The column i used for development has seen 1000+ injections with a 15 minute cycle time (including stonger and different pH 10 buffers) and still performs well. My experience is in aggrement with Doug when we experience column failures it is sample related fouling, not pH.
0 -
Hi, I have found that column lifetimes running at pH10, 60 deg C and moderate back pressures (~8000 psi) on a sub 1 minute method have been very good, usually lasting at minimum 5000 injections. We were getting issues with column fouling, even with the pre column frit but have found that the VanGuard precolumns have solved that problem.
0
