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A method to perform on-line sample preconcentration of serum immunoglobulin E by affinity capture is described. Purified anti-IgE antibodies were covalently bound to an analyte concentrator-reaction chamber or cartridge. The immunoglobulins (IgE) were bound to and eluted from the cartridge by the optimum dissociating buffer system, and the eluent(s) were then subjected to capillary electrophoresis. The first design used was a 5 mm solid-phase cartridge fabricated by assembling a bundle of multiple microcapillaries in which a monoclonal antibody directed against IgE was covalently bound to the surface of every microcapillary. The whole assembly was connected, through sleeve connectors, to the capillary column for affinity capillary electrophoresis. The second design used consisted of an analyte concentrator-reaction chamber that was fabricated from a solid rod of glass. Several small diameter passages or through holes containing a similar surface area was tested for the same experiments and perfor...

A method to measure glutamate in brain dialysates was developed. Nanomolar concentration of glutamate labeled with naphthal-ene-2,3-dicarboxaldehyde (NDA) was measured by using capillary electrophoresis and laser-induced fluorescence detection. The limit of mass detection was in the zeptomole concentration (10−21 M) range. The technique was linear between 10−5 M to 10−8 M. It was possible to reduce the migration time of brain dialysate glutamate to 60 seconds when capillaries of 15 μm inside diameter were used. The potential of capillary electrophoresis coupled to laser-induced fluorescence detection for in vivo monitoring of neurotransmitters is discussed.

The link between brain and reproduction is the release of the decapeptide luteinizing hormone-releasing hormone (LHRH) from the brain median eminence (ME), a release modulated by other neuropeptides such as β-endorphine (BEND) and neuropeptide Y (NPY) impinging on the LHRH neuron. Analysis of brain perfusates is the metnod of choice to determine in vivo release from discrete brain areas. For this, push-pull cannula (PPC) and microdialysis sampling are the most prominent technologies. However, sample volume is a limiting issue when attempting to measure by radioimmunoassays (RIA) in vivo release of multiple neuropeptides from these sources, especially when neuropeptide concentration is low and the whole sample (100 μl PPC perfusate/10 min) has to be dedicated to measure only one neuropeptide. We developed a capillary electrophoresis (CE)-based assay for the simultaneous determination of LHRH, BEND and NPY in PPC samples from the ewe ME. This assay uses CE for the separation of these neuropeptides ...

Humanized anti-Tac monoclonal antibody has been characterized by both SDS-PAGE and isoelectric focusing using traditional polyacrylamide methods. In addition to these techniques, capillary electrophoresis has been adapted to isoelectric focusing in a liquid phase. The humanized antibody has a pl in the range of 8.2–9.0, a region in which precast polyacrylamide or agarose gels are not stable in the 7–10 pH range. Experiments have been conducted to generate gradients in the 3–10 pH range and these gradients have successfully separated differently charged subspecies of humanized anti-TAC. Because of the simplicity in generating a variety of gradients, the power of resolution in different modes, its high efficiency, and the minimum sample volume requirements, capillary electrophoresis may become the method of choice for the routine characterization of therapeutic monoclonal antibodies and their stability profiles.

A quantitative spectrophotometrc assay for the determination of proline and hydroxyproline is described. The assay is based on the derivatization of the imino acids with the fluorogenic chromophore fluorescamine and the separation of the derivatized analytes by capillary electrophoresis. Fluorescamine reacts efficiently with secondary amino acids to form nonfluorescent aminoenone type chromophores which are easily detected at the low UV region. The assay is simple, rapid, and offers a significant improvement in detection sensitivity when compared with standard colorimotric methods for determining these imino acids. Derivatization with fluorescamine also enhances the degree of resolution of the two imino acids, enabling baseline separation of the derivatized analytes.

Two methods were developed using capillary electrophoresis to concentrate urinary constituents in order to collect adequate amounts of separated analytes. the first method utilizes multiple capillaries arranged in bundles and coupled to a single capillary through a glass connector. the second method consists of the use of an analyte concentrator containing an antibody covalently bound to a solid support material. Both methods allow loading of increased amounts of samples into the capillary, and the continuous collection of purified material in nanogram-microgram quantities. the samples collected by the two methods were further analyzed by mass spectrometry.

A quantitative ultraviolet detection method for the determination of urinary metabolites is described using capillary zone electrophoresis. The determination of these metabolites is simple, fast. reproducible and utilizes very small amounts of sample. This method is linear between 1.0 × 10−4 and 1.0 × 10−2 M for creatinine and between 1.0 × 10−1 and 1.0 M for urea. The ultraviolet method shows detection limits for creatinine in the picogram (femtomol) range, and for urea in the nanogram (picomol) range.