Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1990-08-14
1992-01-28
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
264299R, G01N 2627, B01D 5702
Patent
active
050841505
DESCRIPTION:
BRIEF SUMMARY
ity so that separations of the molecules of particular interest can be readily optimized.
The invention provides an electrokinetic method of separating molecular species, in which colloidal particles are provided in a dispersing medium containing a buffer, and the surface of the colloidal particles possesses the ability to interact with at least one of the molecular species to be separated. The colloid and its buffered dispersing medium are placed in a capillary tube, and an aliquot of a sample mixture containing the molecular species to be separated is injected into the capillary tube with the result that the species to be separated distribute themselves between the dispersing medium and the colloidal surface. An electric field is imposed across the length of the capillary tube, causing a separation of the analytes to occur, and the separated materials are finally detected.
The surface of the colloidal particles is employed in its original state provided it has the required interacting capability, or is modified appropriately, for accomplishing a particular separation, by incorporation thereon of chemical functional groups or by addition thereto of material which can interact with species to be separated. In one example of this process, the surface of negatively charged colloidal particles is modified by the addition of positive ions of at least one metal having the ability to interact with the species being separated. In another embodiment, the colloids surface is modified by the incorporation thereon of affinity groups. It is to be emphasized that the foregoing are only a few of many possible examples of the invention.
A capillary column for carrying out the above-described electrokinetic separation of molecular species includes a 0 capillary tube containing colloidal particles in an electrically-conductive dispersing medium, and at least one material having the ability to interact with the molecular species to be separated, this material being located at least in part on the surface of the colloidal material, thereby modifying that surface. Where the colloidal particles as formed have a surface with the requisite interacting ability, however, no further surface-modifying material is necessary.
DESCRIPTION OF THE DRAWING
The invention will be better understood from a consideration of the following detailed description taken in conjunction with the solely exemplary drawing in which:
FIG. 1 shows a schematic diagram of the proposed mechanism for one variant of the separating method, illustrated for a system containing negatively charged colloidal particles, negatively charged analytes, positively charged complexing agents, and a fused silica capillary;
FIG. 2 shows a diagram of the equipment employed in carrying out separations using the method and capillary column of the invention;
FIG. 3 shows an electropherogram of a polythymidine mixture the constituent oligonucleotides of which contain from 2-18 bases, using copper(II) for modifying the colloidal surface;
FIG. 4 shows a separation of the same polythymidine mixture as shown in FIG. 3, but using magnesium(II) in this case for modifying the colloidal surface;
FIG. 5A shows a standard electrophoretic separation of the same polythymidine mixture as shown in FIG. 3, without the use of any colloidal material or surface-modifying complexing agents;
FIG. 5B shows an electrophoretic separation of the same polythymidine mixture shown in FIG. 3, employing as colloidal particles micelles of sodium dodecyl sulfate, but without any surface-modifying complexing agents being present;
FIG. 6 shows the separation of a mixture of oligonucleotides, each of which contains 8 bases, as a function of the complexing agent employed in modifying the colloidal surface; and
FIG. 7 shows the separation of a mixture of 18 oligonucleotides, each containing 8 bases, using the method and capillary of the invention.
DETAILED DESCRIPTION
As used in this document, the terms "colloidal material" and "colloidal particles" mean particles of solid material or groupings of molecules sur
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The Government has rights in this invention pursuant to contract Number Che-7918536 awarded by The National Science Foundation.
This application is a continuation of application Ser. No. 07/374,639, filed June 30, 1989 which is a continuation of application Ser. No. 07/030,225, filed Mar. 24, 1987, now abandoned.
Cohen Aharon
Karger Barry L.
Niebling John
Northeastern University
Starsiak Jr. John S.
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