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Boardwalk :: Forum List Forum Category HPLC Troubleshooting
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 Which is useful, a quaternary pump or binary pump - 2005/06/17 07:09 Dear all,

We are considering getting a HPLC system and hopefully a LC/MS. I am wondering if we should get a quaternary pump or a binary pump. Our applications are somewhat similar to a forensic type of application. We need to analyze a small sample and it is ideal if we can analyze a wide range of compounds in one run. I have used a binary pump and a reversed phase 4.6 mm I.D. column, but I want to develop the method further. For example, the use of narrow bore columns, on-line sample preparation and the use of three different polarities of mobile phases in one run. A quaternary pump seems to be more flexible for these purposes. However, I heard that it is less reliable in terms of delivery of solvents, in particular, those with low flow rate and may be more trouble prone. A binary pump seems to be generally reliable, even when it is used with a low flow rate.
I would appreciate any advice you could give me about this. Thank you.

Post edited by: admin, at: 2005/06/17 07:11
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 Re:Which is useful, a quaternary pump or a binary - 2005/06/17 07:10 I frequently work with flow rates around 0.2 mL/min (LC/MS)and prefer a quaternary pump because of the flexibility. I have only used Agilent's 1100, so I am not familiar with others. We qualify our pumps at several flow rates, and I think that this could be useful with any pump. Another possibility is get your hands on an old HP1090 with a tertiary pump. Those were very reliable.
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 Re:Which is useful, a quaternary pump or a binary - 2005/06/17 07:10 One point you may wish to note when looking at binary vs quaternary pumps is the differences in dead volumes for these. This could become more an issue at low flow rates. Speaking from the point of the Agilent 1100 series the differences can be quite significant. One of the jost significant differences arises from the ways the different systems mix the solvent before delivering it. In the cases of the binary system what appears to be a small empty column is used and in the case of the quaternary pump a chamber filled with ball bearings is used to cause turbulence, hence the mixing. A smaller dead volume exists in the binary system. In the Agilent 1100 capillary system only a binary system is available at the moment and I suspect one of the reasons for this is what I've just mentioned above. This is just one point to consider in the scheme of things. The LC/MS system we use utilizes an Agilent 1100 quaternary pump and is very reliable and support is excellent.
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 Re:Which is useful, a quaternary pump or a binary - 2005/06/17 07:10 Check out the Agilent 1100 OQ/PV documentation. The gradient accuracy spec for the quaternary pump is 1.5% and 0.7% for the binary pump.

As mentioned above the two pumps have a significantly different dwell volume because the pump itself is part of the dwell volume for a quaternary pump but not for a binary pump.

The only method that I have had any trouble transfering between quaternary and binary pump systems was a peptide map on a 3.0mm ID column. We had some transfer difficulity even after compensating for, then matching system dwell volumes.

The problem with the binary pump is you lose the flexibility of online mixing of trinary mobile phases. This greatly hinders our method development.

I recommend the quaternary pump unless your separations require the binary pump. Capilary columns or a very demanding separation might require you to switch to a binary pump.

We have 10 1100s and generally use channel B as a 100% orgainc channel. I have seen the "sticking" MCGV four times in five years. It has always been channel B leaking while filled with ACN. The problem is easily fixed/prevented by purging channel B with hot water.

Good Luck.
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 Re:Which is useful, a quaternary pump or a binary - 2005/06/17 07:13 Definitely, never clean a column feeding a detector.

Be very careful about cleaning columns with reverse flow. They are like cats. They do not mind being scratched backwards but will sometimes react violently to being stroked backwards. If you do back flush, do so with very slow flows and absolute minimum back pressure.
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