On the pH dependence of polymerization efficiency, as investigated by capillary zone electrophoresis

Organic monolithic stationary phases for CEC were synthesized in situ in fused-silica capillaries. Polymerization mixtures were composed of butyl methacrylate, ethylene dimethacrylate, and [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride in the presence of a porogenic solvent, using ammonium peroxodisulfate as chemical initiator, and N,N,N',N'-tetramethylethylenediamine to activate the reaction. The influence of the amount of initiator, temperature, and composition of porogenic solvent on the physical and chromatographic properties of monolithic stationary phases has been investigated. A minimum plate height of 14.5 microm was obtained at 18 wt% of 1,4-butanediol in the polymerization mixture. The produced monolithic stationary phases exhibited a good repeatability and batch-to-batch and mixture-to-mixture reproducibility, with RSD values below 5.6% in the electrochromatographic parameters studied. A comparison with columns prepared by thermal initiation with alpha,alpha'-azobisisobutyronitrile (AIBN) was also performed. The most efficient column initiated with peroxodisulfate showed better efficiencies and selectivities than that prepared with AIBN at the same composition mixture.

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“…The conversion efficiency for methacrylate-based monoliths was evaluated according to the procedure reported by Righetti and co-workers [45,46].…”

Section: Preparation Of Polymeric Monolithic Columnsmentioning

confidence: 99%

Peroxodisulfate as a chemical initiator for methacrylate‐ester monolithic columns for capillary electrochromatography

et al. 2008

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“…This was obviously due to the fact that most of the nonidentifiable proteins were hydrophobic proteins (e.g., membrane proteins). Since these are known to often escape PMF (MALDI-TOF MS) [37] several of the nonidentified protein spots might represent transmembrane proteins.…”

Section: Resultsmentioning

confidence: 99%

Separation of membrane proteins by two‐dimensional electrophoresis using cationic rehydrated strips

et al. 2008

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Due to their poor solubility during IEF membrane proteins cannot be separated and analyzed satisfactorily with classical 2-DE. A more efficient method for such hydrophobic proteins is the benzyldimethyl-n-hexadecylammonium chloride (16-BAC)/SDS-PAGE, but the corresponding protocol is intricate and time-consuming. We now developed an easy-to-handle electrophoresis method in connection with a novel device which enables reproducible separation of ionic solubilized membrane proteins using individually rehydrated plastic sheet gel strips. These strips are suitable for the first dimension in a 2-D 16-BAC/SDS system and can be handled easily; this is demonstrated by the separation of membrane proteins of human embryonic kidney (HEK293) cells.

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“…Although not specifically investigated here, we found some fundamental differences among a number of catalysts as a function of pH of the gelling solution [13]. In riboflavin-driven reactions, there is indeed only a sharp maximum in the pH 6.2-6.5 range, the efficiency slowly declining at more acidic pH values and sharply decreasing in an alkaline pH milieu, to the point of no gelation at pH 10.…”

Section: Effect Of Ph On the Reacting Mixturementioning

confidence: 88%

On the efficiency of methylene blue versus persulfate catalysis of polyacrylamide gels, as investigated by capillary zone electrophoresis

Caglio

Righetti

1993

Electrophoresis

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The efficiency of a novel method of photopolymerization, based on photoinitiating the reaction with methylene blue (MB), in presence of a redox couple (sodium toluenesulfinate and diphenyliodonium chloride), vs, the conventional persulfate--N,N,N',N'-tetramethylethylenediamine redox couple was investigated as a function of different effectors in solution. Oxygen dissolved in the gelling mixture strongly quenches persulfate catalysis, while leaving essentially unaltered the process initiated by photopolymerization. On the contrary, the presence of 8 M urea substantially accelerates a persulfate-driven reaction, boosting the conversion of monomers to near completion (> 98%) while leaving the photopolymerization process largely unaffected. Polyacrylamide polymerization has also been performed in a number of hydroorganic solvents (all in a 50:50 v/v ratio): dimethyl sulfoxide (DMSO), tetramethylurea, formamide and dimethylformamide. In all cases, the persulfate-catalyzed reaction was strongly quenched and even completely inhibited (in DMSO), whereas the photopolymerization process was essentially unaffected by any of these organic solvents. The reaction kinetics of the methylene blue-driven reaction could not be ameliorated when admixing an anionic dye (e.g., eosin Y) to the cationic MB, even when amply changing their molar ratios. Thus, it appears that photocatalysis with MB (and the redox couple sodium toluene-sulfinate and diphenyliodonium chloride) is a unique process, proceeding at optimum rate under the most adverse conditions, completely insensitive to any kind of positive and negative effectors and able to ensure at least 95% monomer conversion under the standard conditions of 1 h reaction time at room temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

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On the pH dependence of polymerization efficiency, as investigated by capillary zone electrophoresis

Cited by 42 publications

References 18 publications

Peroxodisulfate as a chemical initiator for methacrylate‐ester monolithic columns for capillary electrochromatography

Peroxodisulfate as a chemical initiator for methacrylate‐ester monolithic columns for capillary electrochromatography

Separation of membrane proteins by two‐dimensional electrophoresis using cationic rehydrated strips

On the efficiency of methylene blue versus persulfate catalysis of polyacrylamide gels, as investigated by capillary zone electrophoresis

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