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 6,387 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this work, a new physically adsorbed coating for capillary electrophoresis (CE) is presented. The coating is based on a N,N-dimethylacrylamide-ethylpyrrolidine methacrylate (DMA-EPyM) copolymer synthesized in our laboratory. The capillary coating is simple and easy to obtain as only requires flushing the capillary with a polymer aqueous solution for 2 min. It is shown that by using these coated capillaries the electrostatic adsorption of a group of basic proteins onto the capillary wall is significantly reduced allowing their analysis by CE. Moreover, the DMA-EPyM coating provides reproducible separations of the basic proteins with RSD values for migration times lower than 0.75% for the same day (n = 5) and lower than 3.90% for three different days (n = 15). Interestingly, the electrical charge of the coated capillary wall can be modulated by varying the pH of the running buffer which makes possible the analysis of basic and acidic proteins in the same capillary. The usefulness of this coating is further demonstrated via the reproducible separation of whey (i.e. acidic) proteins from raw milk. The coating protocol should be compatible with both CE in microchips and CE-MS of different types of proteins.
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PMID:New physically adsorbed polymer coating for reproducible separations of basic and acidic proteins by capillary electrophoresis. 1450 46

In this work, a comparative study on the use of different polymers as physically adsorbed coatings for CE is presented. It is demonstrated that the use of ad hoc synthesized polymers as coatings allows tailoring the EOF in CE increasing the flexibility of this analytical technique. Namely, different polymers were synthesized at our laboratory using different percentages of ethylpyrrolidine methacrylate (EpyM) and N,N-dimethylacrylamide (DMA). Thus, by modifying the percentage of EpyM and DMA monomers it is possible to manipulate the positive charge of the copolymer, varying the global electrical charge on the capillary wall and with that the EOF. These coated capillaries are obtained by simply flushing a given EpyM-DMA aqueous solution into bare silica capillaries. It is shown that by using these coated capillaries at adequate pHs, faster or more resolved CE separations can be achieved depending on the requirements of each analysis. Moreover, it is demonstrated that these coated capillaries reduce the electrostatic adsorption of basic proteins onto the capillary wall. Furthermore, EpyM-DMA coatings allow the reproducible chiral separation of enantiomers through the partial filling technique (PFT). The EpyM-DMA coated capillaries are demonstrated to provide reproducible EOF values independently of the pH and polymer composition with%RSD values lower than 2% for the same day. It is also demonstrated that the coating procedure is reproducible between capillaries. The compatibility of this coating protocol with CE in microchips is discussed.
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PMID:Capillary electrophoresis using copolymers of different composition as physical coatings: a comparative study. 1647 Jul 81

Two different families of compounds, i.e., phenolic and amino acids have been separated by capillary electrophoresis using a physically adsorbed polymer as capillary coating. The polymer used was N,N-dimethylacrylamide-ethylpyrrolidine methacrylate (DMA-EpyM) and it provided an stable coating by only flushing the capillary with a DMA-EpyM aqueous solution for 2min between runs. The usefulness of this procedure has been demonstrated through the fast analysis of different families of solutes. Two different detection systems, diode-array detector and laser-induced fluorescence, have been used to determine phenolic acids and derivatized amino acids with fluorescein isothiocyanate, respectively. The main factors affecting reversal of electroosmotic flow (EOF) such as pH, type and concentration of buffer, and concentration and influence of organic solvents, as well as all the instrumental conditions were studied and optimized for both families of compounds.
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PMID:Coelectroosmotic capillary electrophoresis of phenolic acids and derivatized amino acids using N,N-dimethylacrylamide-ethylpyrrolidine methacrylate physically coated capillaries. 1907 18

In this work, the properties of four cationic copolymers synthesized in our laboratory are studied as physically adsorbed coatings for capillary electrophoresis (CE). Namely, the four copolymers investigated were poly(N-ethyl morpholine methacrylamide-co-N,N-dimethylacrylamide), poly(N-ethyl pyrrolidine methacrylate-co-N,N-dimethylacrylamide), poly(N-ethyl morpholine methacrylate-co-N,N-dimethylacrylamide) and poly(N-ethyl pyrrolidine methacrylamide-co-N,N-dimethylacrylamide). Capillaries were easily coated using these four different macromolecules by simply flushing into the tubing an aqueous solution containing the copolymer. The stability and reproducibility of each coating were tested for the same day, different days and different capillaries. It is demonstrated that the use of these coatings in CE can drastically reduce the analysis time, improve the resolution of the separations or enhance the analysis repeatability at very acidic pH values compared to bare silica columns. As an example, the analysis of an organic acids test mixture revealed that the analysis time was reduced more than 6-times whereas the separation efficiency was significantly increased to nearly 10-times attaining values up to 595,000 plates/m using the coated capillaries. Moreover, it was shown that all the copolymers used as coatings for CE allowed the separation of basic proteins by reducing their adsorption onto the capillary wall. Links between their molecular structure, physicochemical properties and their performance as coatings in CE are discussed.
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PMID:Connections between structure and performance of four cationic copolymers used as physically adsorbed coatings in capillary electrophoresis. 2097 71