Pros and Cons of two different LC systems

[Malarac]

Hi everyone,

I am after some assistance from anyone who has had experience with Waters and Dionex. My past experience has been with Agilent 1100 and 1200 machines and I know my way around them (and there limitations) well. However, my current lab is looking at purchasing a HPLC system (we already have a detector though) and it will not be an agilent system. The two choices so far are the Dionex U3000 HPLC system and the Waters Alliance (e2695) separations module.
We will be primarily using the system for the fluorescent detection of amino acids (glutamate and GABA) using a derivatisation protocol. Therefore we will be using online derivatisation and the injection program functions of the system (adding various solutions to the sample, mixing, waiting and injecting etc). My main questions involve whether people have had experience with these systems for these type of purposes and whether they had any difficulty due to limitations of the software/equipment?

I am happy to answer any more specific questions if that helps and I appreciate any feedback.
Thanks,
James

[unmgvar]

i have used and also taught 2 other labs to use the dionex hplcs for the application of amino acids
the application requires to do derivatisation and we do it on-line with the sampler
we get great results and reproducibility

the main reason to prefer dionex for our application in this case was the amount of sample
dionex needle picks up from the bottom with a 5ul left over volume in a conical vial
Waters has a side hole needle and so the loss of sample is very high unless you go for those very special and more expensive vials.
we found it not worth

also the dionex compared to alliance from our experience has a sampler with a wash port and a better carryover solution.

[Malarac]

Thanks unmgvar,

pretty much the sort of information I was after. You don't think to ask these questions unless you have encountered issues in the past.

[hema]

You may want to consider a Waters Acquity H-Class instead of the rather old 2695. The H-Class has the hole at the needle tip and is capable of picking up sample with only a few uL leftover in the vial. The autosampler can add derivatisation solutions but is not able to mix or shake. You have to rely on diffusion and therefore wait a few seconds before you draw the sample. Works fine and reproducible though.

The H-Class would probably be a bit more expensive than the 2695. But in the end, you’d invest in the latest technology (UHPLC) making your lab future-proof. This depends of course pretty much on what else you are planning to do with this instrument and whether your current amino acid method can be optimized on a UHPLC in one or the other way (i.e. increased throughput, improved resolution or even both).

I'm telling you this because of my own situation:
The predecessor of my current position bought a classic HPLC intrument right before he left. I have so many ideas what I could do with a UHPLC but the boss won't give me money as we just bought this HPLC system and now I am stuck with this old piece of technology.
In my previous jobs I have never came across problems that could only be solved on HPLC and not on UHPLC. If prize does not matter too much I would never ever buy a classic HPLC system anymore as this is simply out-of-date technology.

Just my opinion.

[jusuom]

Hema,
Maybe you could use columns with 2.6-2.8 micron core-shell/fused-core particles (e.g. Kintex or Ascentis Expresss) with your HPLC?

[Alex Buske]

If prize does not matter too much I would never ever buy a classic HPLC system anymore as this is simply out-of-date technology.

Just my opinion.

Call me old-fashioned, but I still use pen and paper, even though it is uotdated technology. It depends on the needs. Right now, I wouldn't replace our old HPLC workhorses, which run 4000-5000 hrs/a with new technology

I have never came across problems that could only be solved on HPLC and not on UHPLC.
...
The autosampler can add derivatisation solutions but is not able to mix or shake.

Is it possible to use 25 cm columns?
Don't understand me wrong, the H-Class is a good instrument. I am also in trouble with some old instruments.
The Ultimate autosampler can mix and its FL detector can detect up to 4 wavelength combinations. Sensitivity is very good, also in the lamp long-life mode (15000hrs).

Of course the H-class can handle fused core columns. I'd rather use 2mm id rather than 3 or 4.6mm id columns.
alex

[hema]

Alex:
You are absolutely right: It depends. If there is no need then why would you want to change a running system?
However, as technology and methods are constantly evolving and I am only able to invest once in a while in new instruments, I'd try to keep up to date as much as possible. This can be useful if you do method development but it might be different in QC labs with standardized or registered methods.

Is it possible to use 25 cm columns?

Yes you can use 25 cm columns on H-Class. I admit, this requires an external column compartment but is fully controlled by the software. Ok, this adds another few thousand bucks, but I refer to my disclaimer above:

If prize does not matter too much [...]

The Ultimate autosampler can mix[...]

Do you know how the mixing is achieved? Shaking? Stirring?

Thanks!
hema

[Mattias]

I have been quite hard against the Dionex systems, and I still think that their Summit series was a piece of junk. We have spent about 20-30.000 Euro on spare parts during the years we have had them. Close to everything has been exchanged (several power supply boards, autosampler motors, injection valves and much more). We are throwing these away now, despite their low age.

This week I have worked with their Ultimate 3000, and it seems to be a really good piece of equipment. Really a big step up!

[unmgvar]

hema,

you can actually shake the tray of the ultimate, but this is not how you make the mixing
what we do is simply to tell the system to take a certain amount in the needle and to dispense it back in the vial. we play around the dispensing speed as well
in order to increase mixing in conical vials we pick up from the bottom and dispense from "above" by playing around the height needle settings.