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Single Capillary (single + capillary)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Penetration of Porous Systems by Nonwetting Liquids

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2003
S. Palzer
Wetting of porous systems and the corresponding penetration of liquids into single capillaries is one of the most important processes in process engineering. Wetting liquids with a contact angle smaller than 90° are penetrating spontaneously into capillaries. The presented study demonstrates that, under certain conditions, even nonwetting liquids with contact angles larger than 90° can do so. Furthermore, it is shown that the time for such wetting processes can be calculated. [source]

Determination of trace cationic impurities in butylmethylimidazolium-based ionic liquids: From transient to comprehensive single-capillary counterflow isotachophoresis-zone electrophoresis

ELECTROPHORESIS, Issue 23 2006
Marek Urbánek
Abstract Determination of impurities in ionic liquids (ILs) remains a difficult task. In this work, the hyphenation of isotachophoretic,(ITP) preconcentration to zone electrophoresis,(ZE) has been explored for the trace analysis of the cationic impurities Na+, Li+, and methylimidazolium (MI+) in butylmethylimidazolium (BMI+)-based ILs. Simultaneous detection of UV-transparent and UV-absorbing impurities was ensured by a BGE composed of creatinine-acetate buffer. To induce ITP, three different strategies were evaluated: (i),Sample self-stacking ensured by the addition of ammonium acetate (NH4Ac) to 25,50-fold diluted IL solution (transient ITP). (ii),Complete ITP-ZE separation performed in a single capillary: ITP was realized in discontinuous electrolytes comprising an 80,mM NH4Ac, 40,mM acetic acid, 30,mM ,-CD, pH,5.05, leading electrolyte,(LE) and a 10,mM creatinine, 10,mM acetic acid, pH,4.9, terminating electrolyte,(TE). To create the ZE stage, the ITP stack of analytes was moved back toward the capillary inlet by pressure and simultaneously the capillary was filled with the BGE. This protocol made it possible to accommodate a 2.5-times diluted IL sample. (iii),Complete counterflow ITP-ZE with continuous electrokinetic sample supply: the ITP stage was performed in a capillary filled with a 150,mM NH4Ac, 75,mM acetic acid, 30,mM ,-CD, pH,5.0 LE, with 40-times diluted IL at the capillary inlet. BMI+ from IL acts as the terminating ion. The LODs reached in this latter case were at the 10 and 1,ppb levels for MI+ and Li+ in diluted IL matrix, respectively. [source]

In-capillary solid-phase extraction,capillary electrophoresis for the determination of chlorophenols in water

ELECTROPHORESIS, Issue 16 2006
Luo-Hong Zhang
Abstract A novel CE method combined with SPE in a single capillary was developed for analysis of chlorophenols in water. A frit of 0.5,mm was first made by a sol-gel method, followed by packing a SPE sorbent in the inlet end of the capillary. Two phenol derivatives, 2,4-dichlorophenol and 2,4,5-trichlorophenol, were used as the model compounds. By loading sample solutions into the capillary, the two chlorophenols were extracted into the sorbent. They were desorbed by injecting only about 4,nL of methanol. Finally, the analytes were separated by conventional CE. The technique provided a concentration enhancement factor of over 4000-fold for both chlorophenols. The detection limits (S/N,=,3) of 2,4-dichlorophenol and 2,4,5-trichlorophenol were determined to be 0.1,ng/mL and 0.07,ng/mL, respectively. For replicate analyses of 5,ng/mL of 2,4-dichlorophenol, within-day and between-day RSDs of migration time, peak height and peak area were in the range of 1.8,2.0%, 4.0,4.4% and 4.1,4.6%, respectively. The method shows wide linear range, acceptable reproducibility and excellent sensitivity, and it was applied to the analyses of spiked river water samples. The capillary packed with the SPE sorbents can be used for more than 400 runs without performance deterioration. [source]

Crystallization and diffraction patterns of the oxy and cyano forms of the Lucina pectinata haemoglobins complex

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2009
Carlos R. Ruiz-Martínez
The native oxygen-carrier haemoglobins complex (HbII,III) is composed of haemoglobin II (HbII) and haemoglobin III (HbIII), which are found in the ctenidia tissue of the bivalve mollusc Lucina pectinata. This protein complex was isolated and purified from its natural source and crystallized using the vapour-diffusion and capillary counter-diffusion methods. Oxy and cyano derivatives of the complex crystallized using several conditions, but the best crystals in terms of quality and size were obtained from sodium formate pH 5 using the counter-diffusion method in a single capillary. Crystals of the oxy and cyano complexes, which showed a ruby-red colour and nonsingular prismatic shapes, scattered X-rays to resolution limits of 2.15 and 2.20,Å, respectively, using a 0.886,Å synchrotron-radiation source. The crystals belonged to the tetragonal system, space group P42212, with unit-cell parameters a = b = 74.07, c = 152.07 and a = b = 73.83, c = 152.49,Å for the oxy and cyano complexes, respectively. The asymmetric unit of both crystals is composed of a single copy of the heterodimer, with Matthew coefficients (VM) of 3.08 and 3.06,Å3,Da,1 for the oxy and cyano complexes, respectively, which correspond to a solvent content of approximately 60.0% by volume. [source]