Bio-rad Laboratories, Inc.

Christopher J Siebert

Stellan Hjerten

Rand Dill

Jia-li Liao

Jia-Li Liao

James F Monthony

Ming-De Zhu

Rong Zhang

The present invention provides new methods for the concentration of ionic solutes, particularly ampholytes, such as, for example, peptides, proteins and nucleic acids. The methods are based on the fact that the electrophoretic migration velocities of solutes decrease upon a decrease in the absolute value of the zeta-potential of a solute or the pore size of the electrophoresis medium, and upon an increase in the cross-section of the electrophoresis chamber, the viscosity of the electrophoresis medium, or the electrical conductivity of the electrophoresis medium. When applied to capillary electrophoresis, the methods described herein permit concentration of a solution of solutes in the same capillary tube as is used for the electrophoretic analysis. Alternatively, however, the sample can be withdrawn from the capillary tube following concentration of the solution of solutes and processed by techniques other than high-performance capillary electrophoresis (HPCE).

Concentration of biological samples on a microliter scale and analysis

The phenomenon of electroendosmosis which occurs in electrophoretic separations and interferes with the efficiency, accuracy and reproducibility of the separations, is suppressed by the inclusion in the separation medium of a dissolved hydrophilic polymer which has been modified by amine groups covalently bonded thereto, in a controlled proportion relative to the polymer. This modified polymer suppresses electroendosmosis in both flee zone electrophoresis and molecular sieve electrophoresis. When this modified polymer is used in a capillary, the reduction which it produces in the electroendosmosis is the same as that achieved by coating the capillary wall with a neutral polymer.

Suppression of electroendosmosis during electrophoresis in gel-free

The present invention provides new methods for desalting samples of ionic polymers or weak electrolytes, preferable ampholytes (e.g., peptides, proteins and glycoconjugates) or, compounds which can be transformed into these substances by complex formation. The methods of the present invention are based on the fact that salts can be removed from a sample by electrophoretically replacing the salts with ampholytes present in the ampholytic media of the anolyte and the catholyte or, with displacing cations and anions that have been introduced into the anolyte and catholyte, respectively, and which have mobilities less than the mobilities of the cations and anions to be removed from the sample. Although applicable to both small-volume and large-volume samples, the methods are particularly well suited for small-volume samples. Moreover, when applied to capillary electrophoresis, the methods described herein permit desalting of a sample in the same capillary tube as is used for the electrophoretic analysis. Alternatively, however, the sample can be withdrawn from the capillary tube following desalting and processed by techniques other than high-performance capillary electrophoresis (HPCE). Regardless of which method is used, the desalting methods of the present invention are rapid, highly reproducible, and they give a high recovery of sample compared to dialysis.

Methods for the desalting of biological samples: a simple approach to

A cartridge for high performance capillary electrophoresis is constructed to accommodate a capillary with a flexible length of tubing surrounding it for the passage of a liquid coolant. Connections and fittings in the cartridge permit quick insertion and removal of the capillary and coolant tube so that capillaries of different lengths can be used with the same cartridge. Apertures in the cartridge body permit the capillary and tubing to be looped outside the cartridge so that different lengths can be connected without the need to coil the capillary inside the cartridge body. A removable capillary aligning device is also disclosed, which fits in the cartridge in a fixed orientation and holds the capillary in alignment with lenses if used and a light beam passing through the cartridge.

Capillary aligning device for on-line optical detection

HPCE capillary cartridge for uncoiled capillaries with liquid coolant

Gels for electrophoresis such as polyacrylamide gels are formed in a neutral pH medium containing a salt solution of preselected concentration. This salt is incorporated in the gel and in subsequent use in electrophoresis is displaced upon application of an electrical potential (direct current) by ionic species which form a pH buffer in the gel. Prior to introduction of the buffer, the gel containing the neutral salt is storage stable for prolonged periods of time. The gel is reproducible since it is always formed under the same conditions and the buffer only thereafter introduced.

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Berkeley, CA, United States of America

Christopher J Siebert