Need advice on uHPLC pump purchase

[BHolmes]

Going to purchase a new Thermo Scientific uHPLC pump for our Ultilimate 3000 system and I would appreciate some feedback on the two options we have:
1. LPG-3400SD Quaternary Analytical Pump (Part No. 5040.0031)
2. HPG-3400SD Binary Analytical Pump w/Solvent Selection Valve (Part No. 5040.0041)
for additional product information and the design of these two pumps please refer to pages 6-7 of this brochure:http://www.thermoscientific.com/content ... -Pumps.pdf

With option 2 we would also need to purchase SRD 3400 Solvent rack w/4 degasser channels (Part No. 5035.9245). Option 1 has degasser channels included as part of the pump module. This is not a major concern as our budget allows for either purchase. We are more concerned with the accuracy and precision of the pump and gradient formation.

Option 1 uses low-pressure proportioning for gradient formation, whereas option 2 uses high-pressure proportioning. We routinely run gradient analysis, so would high-pressure be better for our application? Also we run at high pressures using core-shell technology columns.

We would prefer responses from actual users of Thermo Systems or similar setups from different manufacturers. We are planning on making this purchase in the next 6 months or so. Looking forward to the discussion! Thank you!

[Klaus I.]

Here is an ongoing discussion about low- and high-pressure systems in general:
http://chromforum.org/viewtopic.php?f=1&t=26208

I think most of the users prefer high-pressure systems since they seem to be more robust. Nevertheless most applications can be done with both systems.

I’m not sure what the ‘u’ in ‘uHPLC’ means for your applications, but are you aware about the pressure limit (620 bar) of the ‘SD’ series?