Binary pump applications

[aldehyde]

Hi all, I was thinking recently about the internal flow path of quartenary and binary pumps and reviewed some documents explaining things. The quartenary pump mixes solvents at the multi channel gradient valve prior to entering the pump, so the mixing occurs at low pressure. With a binary pump two pump heads are used and the pumped fluids are combined under high pressure and subject to additional mixing.

As far as I can tell the only benefit to a binary pump is the higher gradient precision gained by pumping at high pressure, are there examples of methods that absolutely require a binary pump?

It seems like having two pump heads is just a ridiculous expense and repair hazard for such a small benefit.

I imagine there must be some solvent compositions that require high pressure mixing to function correctly?

edit: also, seal wash. Is it worth having a bunch of weird tubes all over your pump?

[tsoukalas1]

Hello,

I copy/paste a small abstract made by Agilent explaining differences between quat and binary pump :

"
The Agilent 1260 Infinity LC family offers two analytical scale LC gradient pump types:
a quaternary low pressure mixing pump and a binary high pressure mixing pump. Both
pumps show excellent performance within their design range. The optimum gradient
range for the quaternary pump is between 5% to 95% organic. The binary pump
shows optimum performance from 0% to 100% organic, which is advantageous for
compounds eluting at very low or at very high organic percentage. In the range of 5%
to 95% organic both pumps show comparable performance. Another advantage for
the binary pump is the high mixing efficiency, which is necessary if TFA is used as a
modifier. At high flow rates and fast gradients, both pumps show excellent retention
time precision. The quaternary pump has the advantage that ternary and quaternary
gradients can be applied "

I prefer quaternary pump, because binary pump is more expensive to maintain => 2pump Head and I don't need binary pump performance.

Have a good day

pierre

[aldehyde]

Yeah thats basically what I was getting at, seems like you could use some other tricks to optimize those hard to separate peaks, rather than paying for basically double the pump and twice as much to repair if anything goes wrong .

[Gaetan Glauser]

High pressure mixing systems (binary pumps) have much lower dwell volumes than low pressure mixing systems (quaternary pumps). In practice, this means you can save quite some time during your analysis (avoiding unwanted isocratic initial hold and long re-equilibration because of large dwell volume). This is especially important when running ballistic gradients of a couple of minutes in UHPLC.

I think it depends on your every day work: if you do a lot of method development with complex solvent mixtures such as ternary or quaternary mixtures (which BTW is rarely necessary), a quaternary pump may be the best option. If you do mainly very rapid analyses in UHPLC and saving time is your priority, better have a binary pump with low dwell volume. I would however be interested in other people's opinions...

[aldehyde]

Great point.. I would have thought that the dwell volume would be slightly larger because of the extra tubing used to do the mixing, but the reference materials I'm looking at agree with you.

Generally I see people with their quartenary pump set up for solvents A and B and then channels C and D are just sitting ignored in a wash bottle or are stuck in the same bottles as A and B hehe.

[HPLCaddict]

High-pressure systems tend to have smaller dwell volumes because the mixed fluids don't have to go the whole way through the pump heads as in low-pressure mixing. The extra tubing is neglectable.

For routine HPLC work, I'd prefer quaternary systems, mainly because they usually have better mixing capabilities, resulting in less noisier baselines (esp. with TFA applications), and less maintenance requirements (and less costs!). Plus the addon of greater flexibility - even though the majority of methods I use require not more than to eluents, you may use the extra channels for flushing solvents or the like. For method development, quaternary systems are unbeatable. Use every channel with buffers of different pH and/or different organic modifiers and let it run overnight...can't do that with high-pressure mixing unless you use solvent switching valves.

We have some high-pressure mixing systems for UHPLC applications. They actually DO show better gradient proportioning, especially in the extremes (0-5%, 95-100%) and of course have way less dwell volumes - a must if you want to run fast gradients. Actually there are UHPLC systems with quaternary mixing on the market, I just don't have experience with them.

Both systems have their benefits and their disadvantages, I guess that's why both still exist . You have to evaluate for yourself, which systems fits better to your needs...

[lmh]

Some quaternary systems don't work very well at low pressure, but every binary system I've used will pump an accurate gradient down to the very lowest back-pressures. Again not terribly relevant as it's never hard to increase back-pressure if you want to!

[aldehyde]

Well thank you all for your comments, I work on a bunch of different instruments but mainly GCMS.. so when it comes to LC I'm still pretty novice .