Journal of capillary electrophoresis and microchip technology最新文献

A chiral separation model of gel electrochromatography in a polydimethylsiloxane (PDMS) microfluidic device for amino acids (AAs) is presented. Six pairs of fluorescein isothiocyanate (FITC)-labeled dansyl amino acids (Dns-AAs) were separated in a 36-mm effectual separation channel in less than 120 sec, with resolutions all above 0.96. This highly efficient PDMS chiral microfluidic chip was prepared by inserting the mixture solution of monomers, crosslinkers, and radical initiation into the microchannel via syringe. Specifically, allyl-gamma-cyclodextrin (CD) as a chiral selector and crosslinker was bonded in gamma-CD-bonded polyacrylamide (PAA) gel, which was the separation media, and was immobilized in a PDMS microchannel through the stable linkage of 3-(trimethoxysilyl)-propyl methacrylate (Bind-Silane, Sigma, St. Louis, MO, U.S.A.). The preparation not only permitted the prompt chiral separation of AAs, but also extended application of the PDMS microfluidic device by restraining its hydrophobicity through the PAA gel monolithic column. Furthermore, the longevity of the PDMS microfluidic device was prolonged significantly. This can also be a powerful way to develop a rapid and efficient bioanalysis method and portable analytical apparatus.

Capillary electrophoresis is still widely used for DNA sequencing. The quality of the replaceable sieving matrix is a key area for massive sequencing with regard to speed and efficiency. The T25 polymer has been tested extensively and compared to poly(N,N-dimethylacrylamide) (PDMA). In terms of peak resolution, both polymers perform similarly. On the other hand, the run time is much shorter with the T25 polymer.

In this study, a novel electrochemical detection system for capillary electrophoresis was proposed. In the proposed system, sheath flow would transport analytes to the working electrode surface to allow electrochemical detection. The sheath-flow electrochemical detector would require no modification of capillaries and could accommodate capillaries larger than 25 microm i.d.

Voltage gradient partial-filling affinity capillary electrophoresis (VGPFACE) is used to determine binding constants between carbonic anhydrase B (CAB, E.C.4.2.1.1) and arylsulfonamides, and vancomycin (Van) from Streptomyces orientalis and teicoplanin (Teic) from Actinoplanes teicomyceticus and D-Ala-D-Ala terminus peptides. Two variations of VGPFACE are described herein. In the first technique, the capillary is partially filled with ligand at increasing concentrations followed by a sample containing receptor and two noninteracting standards and electrophoresed in buffer using a voltage gradient that increases from 0 to 25 kV over the duration of the experiment. Upon continued electrophoresis, zones of solution overlap, and equilibrium is established between the ligand and receptor, causing a shift in the migration time of the receptor with respect to the noninteracting standards. This change in migration time is utilized for estimating a binding constant (K(b)). In the second technique, voltage gradient partial-filling multiple-injection ACE (VGPFMIACE), a multiple-injection sequence is used whereby the capillary is partially filled with ligand at increasing concentrations, a noninteracting standard, three or four separate plugs of receptor each separated by small plugs of buffer, and a plug containing a second noninteracting standard; this is then electrophoresed in buffer with a similar voltage gradient. Upon continued electrophoresis, a similar equilibrium is established and a value for K(b) is obtained for the interaction. The VGPFACE technique expands the functionality and potential of ACE as an analytical tool to examine various receptor-ligand interactions.

Heteroduplex analysis is the most popular method for double-stranded DNA mutation detection thus far. Since different DNA fragments have various melting temperatures due to different base pair compositions and sizes, the PCR-amplified DNA fragments need to be denatured, generally, over 90 degrees C and reannealed to give a mixture of four duplexes, two homoduplexes, and two heteroduplexes for electrophoresis or chromatographic analysis. To separate homoduplex and heteroduplex DNA fragments, the column temperature must be controlled at the DNA melting temperature. This is tedious for DNA mutation study, since the melting point has to be measured before heteroduplex analysis. A novel heteroduplex analysis method using a capillary electrophoresis-laser-induced fluorescence (CE-LIF) detection system is described in this paper for the separation of all homo- and heteroduplex DNA fragments, which have different melting temperatures, at a single temdegrees C, 64 degrees C, and 70 degrees C--were separated and detected. The assay is simple, accurate, and sensitive, giving it potential for multiplex analysis for DNA mutation study.

Capillary zone electrophoresis with electrochemical detection has been used for the separation and determination of scopoletin, hyperin, chlorogenic acid, and quercetin in Mutouhui. The effects of several important factors, including running buffer acidity, separation voltage, and working potential, were evaluated to achieve the optimum conditions. The working electrode was a 300-microm carbon disk electrode at a working potential of + 0.95 V (versus saturated calomel electrode). Under the optimum conditions, the analytes can be well separated within 20 min in a 75-cm-long fused-silica capillary. The current response was linear over two orders of magnitude with detection limits (S/N = 3) ranging from 2.70 x 10(-8) g/mL to 1.30 x 10(-7) g/mL for all analytes. This method was used successfully in the analysis of Mutouhui, and the assay results were satisfactory.

The development and experimental optimization of a novel flow injection-capillary electrophoresis (FI-CE) analyzer employing UV-visible fiber optic detection is described. The analyzer incorporates a miniature charge-coupled device (CCD) spectrometer and operates in a graphical programming environment. Data from experimental optimization studies and small molecule separations involving affinity capillary electrophoresis (ACE) and indirect detection of anions are presented. Future directions in terms of instrument automation and incorporation into a microfluidic format are also discussed.

In this report, the most recent results regarding the use of microchip-capillary electrophoresis and pulsed electrochemical detection are reviewed. This article is particularly focused on the analysis of three groups of compounds: phenolic contaminants, phenolic acids, and phenolic antioxidants. Background information and a brief discussion covering other related analytical strategies are also included.