Binairy and quaternary pumps

[Jorim]

I'm working on a HPLC project and I like to know what the main difference is between a binary and a quaternary pump, in which situation should I use the binary pump and in which situation the quaternary pump?

Thanks!

Jorim

[DR]

Binary = 2, Quarternary = 4 solvents to choose from. Most chromatography is accomplished with 1 or 2 mobile phases. Quarternary systems are rarely needed to get a separation done, but they are frequently used for post analysis 'clean-up' of a column and system.

There is another consideration too - high or low pressure mixing. Some binary systems and, (as far as I know) all quarternary systems use a proportioning valve and gravity to dispense the mobile phases into a small mixing chamber, then pump the resulting mixture into the column. High pressure systems use a pump for each of the mobile phases and the mixing chamber is between the pumps and the column. This typically allows for a smaller mixing chamber and more efficient mixing with less outgassing but is more expensive.

[Jorim]

There is another consideration too - high or low pressure mixing. Some binary systems and, (as far as I know) all quarternary systems use a proportioning valve and gravity to dispense the mobile phases into a small mixing chamber, then pump the resulting mixture into the column. High pressure systems use a pump for each of the mobile phases and the mixing chamber is between the pumps and the column. This typically allows for a smaller mixing chamber and more efficient mixing with less outgassing but is more expensive.

So, if I understand you correct, if you want to use high pressure you need (as far as you know) binary pumps? Small thing, what is high ??

[Mark]

Jorim,

Most of the high pressure mixing systems use a separate pump for each solvent, i.e. binary uses 2 pumps, trinary uses three pumps, etc. High pressure mixing means that the mixing is done on the outlet side of the pumps (the "high" pressure side). Low pressure mixing can be accomplished by mixing in the pump head using proportioning valves (i.e. Varian Prostar system) or using an external proportioning valve like some of the older Waters systems.

Regards,
Mark

[tom jupille]

Here's a link to a free on-line course about HPLC that may help clarify some of the issues:
http://www.lcresources.com/resources/getstart/index.htm

[DR]

or using an external proportioning valve like some of the older Waters systems.

and newer ones (Alliance, for example).