I am with Gilson Inc. We have developed a capillary pumping system capable of delivering gradient flow rates down to 100 nl/min with out splitting. I am trying to determine how many people are working with Capillary LC and specifically Capillary LCMS. Does anyone know how big of a demand there is for this type of technology or if the demand will be coming in the future?

This system removes all the problems associated with using splitters.

Thanks,

Luke Roenneburg
Application chemist
Gilson Technical Support

I would give as a conservative guess that we have about 15-20 cap LC/MS units at the location where I work. I also know that one department has budgeted for 9 new units this year. I believe 4 are already in and have been installed. Any of the other sites in the company, I don't know about.

we use mainly cap LC and LC/MS. the only issue that i'd be worried about is the amount of dead volume in the pump. if I'm running a gradient at a flow of 100 nL/min and the pump has a dead volume of 1 uL, it would kill my gradient. very interested in your system otherwise. i'm glad somebody is tailoring their equiptment to capillary LC. what do you estimate the dead volume to be?

The pump dead volume (meaning from pump inlet to pump outlet is 37 ul. This is very small in comparison to other cap LC systems (which most are analytical pumps with splitters) and this volume is not really crucial. The place were the dead volume is critical is in the Mixer and in the tubing post mixer. The mixer we offer has a dead volume of 60 nl. We recommend having the shortest possible connection from mixer outlet to the injector valve. I would recommend at the 100 nl flow rate to use a maximum of 6 cm of 25-50 um ID capillary tubing from mixer outlet to injector valve inlet. Please let me know if what I am saying on the pump dead volume makes sense. Also, I mentioned the pump has a void volume of 37 ul and the piston stroke volume is 39 ul.

Luke,
Running a gradient at 100 nL/min using a pump with a volume of 37 uL. To re-equilibrate this system at this flow would take about 18 hours with these conditions. (3 X 37 uL) / 0.1 uL/min = 1110 min.

Anonymous,

Two run a gradient requires two pumps. Each pump contains one of the gradient solutions. Therefore the entire volume of the pumps is filed with this solution up to the mixer inlet. This never changes for either of the pumps. The only thing that changes is the percentages of pump1 vs pump2. The only volume that you have to take into consideration for equlibration is the void volume of the mixer (60nl), column volume, and the volume of the tubing post mixer as well as the volume of the Flow cell (if using UV detector).

Re-equilibration should be roughly around 10 min. if all the tubing volumes have been minimized. And I am erroring on the excess. I have gradient data to show this.