Methods and apparatus for making a chromatography column
Methods for depositing a stationary phase in a tube for chromatography, in particular, as a variable gradient column are disclosed. The methods include providing a tube having a first end and a second end, the tube containing a fluid composition comprising a stationary phase precursor and a solvent, connecting the first end of the tube to a flow device, removing the solvent from a meniscus of the fluid composition, the solvent exiting the tube at the second end, and operating the flow device while removing the solvent such that the amount of the stationary phase precursor deposited within the tube changes as the meniscus retreats within the tube to deposit a stationary phase having a thickness gradient along the length of the interior of the tube.
1. A method for depositing a stationary phase in a tube for chromatography, the method comprising:
providing a tube having a first end and a second end, the tube containing a fluid composition comprising a stationary phase precursor and a solvent;
connecting the first end of the tube to a flow device;
removing the solvent from a meniscus of the fluid composition, the solvent exiting the tube at the second end; and
operating the flow device while removing the solvent such that the amount of the stationary phase precursor deposited within the tube changes as the meniscus retreats within the tube to deposit a stationary phase having a thickness gradient along the length of the interior of the tube.
2. The method of claim 1 wherein the tube has a generally uniform cross-sectional area along its length, and the stationary phase has a generally reducing thickness from the first end to the second end of the tube.
3. The method of claim 1 wherein the tube has a generally enlarging cross-sectional area along its length; wherein the loading step includes introducing a decreasing concentration of the stationary phase precursor from one end of the tube to the other end thereof; wherein the stationary phase is deposited in the tube as a layer of generally uniform thickness.
4. The method of claim 1 wherein the tube has a generally non-uniform cross-sectional area along its length; wherein the loading step includes introducing a decreasing concentration of the stationary phase precursor; wherein the stationary phase is deposited in the tube as a layer of generally non-uniform thickness.
5. The method of claim 1 wherein the tube includes a narrower cross-sectional area at the first end relative to the cross-sectional area at the second end, and wherein the stationary phase has a generally reducing thickness from the first end to the second end.
6. The method of claim 1 wherein the removing step includes evaporating the solvent.
7. The method of claim 1 wherein the removing step includes controlling the temperature of the tube.
8. The method of claim 1 wherein the flow device includes a syringe pump, a high pressure liquid chromatography pump, a peristaltic pump, a gravity feed device, and combinations thereof.
9. The method of claim 1 wherein the tube includes a surface area-increasing member within the tube; wherein the stationary phase precursor is deposited on the surface area-increasing member.
10. The method of claim 1 wherein the stationary phase is thicker at the first end and is thinner at the second end of the tube.
11. The method of claim 10 wherein the stationary phase varies along the length of the tube as a linear or non-linear function from the first end to the second end.
12. The method of claim 1 wherein the flow device includes a syringe pump, a high pressure liquid chromatography pump, a peristaltic pump, a gravity feed device, or a combination thereof.
13. The method of claim 1 wherein the tube includes a surface area-increasing member within the tube; wherein the stationary phase precursor is deposited on the surface area-increasing member.