Journal of capillary electrophoresis and microchip technology最新文献

Capillary electrophoresis using a capillary coated with a double-strand coating of polyaniline:poly(methyacrylate-co-acrylic acid) (PAN:P[MA-AAI) was used to separate advanced glycation endproducts (AGEs) formed at 37 degrees C from model systems containing either glucose (Glc), fructose (Fru), or glyceraldehyde (GA) and N-alpha-acetyl-L-lysine (NALys). The presence of the P(MA-AA) as a second strand in the polymer allows the maintenance of the conductive state of the PAN at a wide pH range. Effects of buffer pH and coating concentration on the electroosmotic flow (EOF) were investigated. More AGE species can be detected for the GA/NALys mixtures using this coated capillary than upon an uncoated capillary. The coating procedure is simple and the stability of the coated capillary is good.

DNA analysis on microchannel plate (MCP) capillary electrophoresis platforms will be advanced by the development of new methods for the fluorescence labeling of analytes and standard sizing ladders. Here we evaluate end-labeling of commercially available DNA ladders and polymerase chain reaction (PCR) amplicons with terminal deoxynucleotidyl transferase (TdT) as a method for fluorescent double-stranded DNA sizing analysis. A PCR-based procedure for the facile construction of custom energy-transfer-labeled DNA sizing ladders is also presented. High-resolution sizing of single-stranded DNA fragments is demonstrated with this energy-transfer-labeled ladder. These DNA labeling procedures will be useful for double-and single-stranded DNA analyses on microdevices and other electrophoretic platforms.

HPLC often meets with difficulty in analyzing reactive dyes, their activation, and posterior hydrolysis. In this work, capillary electrophoresis methodology for two reactive dyes, C.I. Reactive Black 5 and C.I. Reactive Red 198, was studied. The methods developed permit the separation and detection of these reactive dyes and their major hydrolytic products. These methods can be used successfully for the optimization of these dye syntheses, purification process, formulation, and also to monitor effluents and dye-bath mixtures and extrapolation to similar compounds. Simple background electrolyte systems, such as 10 mM phosphate or 0.65% hydroxypropylmethylcellulose in 40 mM acetate, were used to follow the hydrolysis mechanism and process in the two different alkali media studied.

An amplification system was used in this study to evaluate the effect of sample preparation and its injection on the electrophoretic separation by capillary electrophoresis using a commercially available capillary electrophoresis instrument. The effect of dilution of amplified samples in water and in different sources of formamide (with conductivity values ranging from 47 to 1000 microS) was evaluated, as was contamination of the sample with high DNA concentrations or buffer salts. Although resolution remained constant in the different solvents tested, the sensitivity increased in samples diluted in water and high-purity formamide. An on-column sample preconcentration method for capillary-based DNA analysis was evaluated to increase the sensitivity of low-quality samples. This technique, pH-mediated sample stacking, is based on the injection of NaOH immediately before sample injection: A neutralization reaction occurs between OH- and tris+ ions so that a low-conductivity zone is created at the head of the capillary. DNA fragments are concentrated at the front of this zone. Using coated capillaries with hydroxycellulose 2% (MW 250,000) as a separation matrix, an improvement in sensitivity was detected in all the solvents studied. The gain in sensitivity was higher for more conductive solvents, and was not correlated with the size of the DNA fragments.