Hello,

I'm interested in trying to do some HPLC at pressures around 15000 psi using 2u or 1.5 u
silica. First, I need a pump. Does anyone know of a pump that will work at that pressure, or one that can be modified to work at that pressure (or just near it) ? I have several Hitachi 6000 series pumps that I wouldn't mind mangling.

The old Beckman model 100 that went up to 10,000 psi is the highest pressure commercial pump I've heard of. Of course you could use the Haskal-type pneumatic amplifier pumps like are used to pack columns, but these are constant pressure, not constant flow.

Tom,
I remember hearing Jim Jorgenson speaking on Ultra-high Pressure LC a few years ago. Below I've list two of his references. Take a look at them and see what he did to get ultra-high pressures. I do remember he had safety concerns at those pressures and encased the LC in a plexiglass box.

I hope these references are fruitful for you

Title
"Ultrahigh-pressure reversed-phase liquid" chromatography in packed capillary columns.
Author
MacNair JE; Lewis KC; Jorgenson JW
Address
Department of Chemistry, University of North Carolina at Chapel Hill 27599-3290, USA.
Source
Anal Chem, 69(6):983-9 1997 Mar 15
Abstract
The use of extremely high pressures in liquid chromatography can improve the efficiency and reduce analysis time for columns packed with small particles. In this work, fused-silica capillaries with inner diameters of 30 microns are slurry packed with 1.5 microns nonporous octadecylsilane-modified silica particles. These columns are prepared in lengths up to 66 cm with packing pressures as high as 4100 bar (60,000 psi). Near the optimum flow rate, columns generate as many as 300,000 theoretical plates for lightly retained compounds (k' < 0.5) and over 200,000 plates for more retained compounds (k' approximately 2). These translate to plate heights (Hmin) as low as 2.1 microns. The pressures required to run at optimum flow rates are on the order of 1400 bar (20,000 psi). Analysis times at these pressures are on the order of 30 min (k' approximately 2) and can be reduced to less than 10 min at higher than optimum flow rates. Capacity factors are observed to increase linearly with applied pressure.
Language
Eng
Unique Identifier
97229837


Title
"Ultrahigh-pressure reversed-phase capillary" liquid chromatography: isocratic and gradient elution using columns packed with 1.0-micron particles.
Author
MacNair JE; Patel KD; Jorgenson JW
Address
Department of Chemistry, University of North Carolina at Chapel Hill 27599-3290, USA.
Source
Anal Chem, 71(3):700-8 1999 Feb 1
Abstract
Fused-silica capillaries with inner diameters of 33 microns and lengths of 25-50 cm are slurry-packed with 1.0-micron nonporous octadecylsilane-modified (C18) silica spheres. These columns are used to perform ultrahigh-pressure reversed-phase liquid chromatographic analyses in both isocratic and gradient elution modes. Mobile-phase pressures as high as 5000 bar (72,000 psi) are applied to column inlets to generate more than 200,000 theoretical plates in 6 min (k' approximately 1) for small, organic analytes. Average capacity factors of analytes are found to increase linearly with applied pressure. An electrically driven constant-flow syringe pump capable of generating mobile-phase pressures as high as 9000 bar (130,000 psi) is described. This pump is used in conjunction with an exponential dilution method for the gradient separation of peptides from a tryptic digest on a 27-cm-long capillary packed with 1.0-micron particles. A peak capacity of 300 is demonstrated for a 30-min analysis.
Language
Eng
Unique Identifier
99143978

Tom,

I have made a simple syringe that can be made cheaply and adapted to most syringe drive pumping systems. The syringe that I built was tested up to 10,000 psi (the limit of our pressure gauge); however, simply making the teflon seal longer will enable you to go to higher pressures. Here is the paper:

An Affordable High-Performance Pumping System for Gradient Capillary Liquid Chromatography

J. Microcolumn Separations, 11(4) 299-304, (1999)

If you can not get a copy of the paper let me know and I can fax a copy to you. Contact me at

TSKephart@aol.com

Scott Kephart
Lubbock, TX

One of Jorgenson's current students has developed modifications for a Waters 510 (or similar) pump for pressures in your range of interest. the student might even modify one for you for some$$. I would be interested in your success in this project as we are contemplating something similar.