Biomedical subjects

B Wenclawiak

Publications and source records attributed to B Wenclawiak.

4 recordsLinked to original sources

PubMed2006

Electroosmotic flow patterning using microfluidic delay loops.

A theoretical and experimental investigation of alternating electroosmotic flow patterns by means of specially designed delay loops is presented. Using elementary methods of compact network modeling and detailed FEM simulations the flow behavior and, in particular, the rearrangement of sample plugs is modeled. The proposed designs rely on flow splitting in combination with electroosmotic delay loops leading to a runtime difference or phase shift between two sub-streams. Due to this phase shift, a new fluid interface is generated at the merging point. The approach is experimentally validated by injection of a Rhodamine 6G solution into an aqueous sodium tetraborate buffer.

Borates↗

PubMed2000

Carbon-based quantitation of pyrethrins by supercritical-fluid chromatography.

All six insecticide active ingredients in pyrethrum extract were quantified by supercritical fluid chromatography and carbon calibration. Allethrin is a suitable reference compound for carbon calibration and pyrethrins calibrations. Carbon quantification in SFC is also applied to pyrethroids (phenothrin, permethrin, cypermethrin, fenvalerate and deltamethrin) and alkanes. Halogen substitution on pyrethroids requires halogens on the reference calibration compound. The method was applied to commercial extracts.

Alkanes↗

PubMed1996

High-performance liquid chromatographic determination of primary amines in aqueous solutions after extraction and derivatization with 2,2-diphenyl-1-oxa-3-oxonia-2-boratanaphthalene (DOOB).

Aqueous solutions of tryptamine, tyramine and ethanolamine are extracted and derivatizated to azomethine chelates using a solution of DOOB in diethyl ether. The extraction takes about 2 h. Diisopropyl ether and toluol have also been tested as extractants. The separation of the azomethine chelates is realized by a gradient program on a Si 60 column using a mixture of n-heptane/tert-butyl methyl ether. UV detection is carried out at 280 nm. The concentration of these three amines has been determined in a Chianti wine sample.

Journal Article↗

PubMed1984

High-performance liquid chromatographic investigations on the time-dependent reaction of cis-Pt(NH3)2Cl2, Pt(en)Cl2 and Pt(pn)Cl2 with RNA fragments.

The reaction of three platinum compounds, Pt(NH3)2Cl2, Pt(en)Cl2 and Pt(pn)Cl2 with nucleic acid fragments (Ade, Gua; GpG, GpA and ApA), both reactants (1:1, 1 X 10(-2) M; 1 X 10(-3) M) being dissolved in water, has been studied. UV measurements have been used to characterize the products. Kinetics and adduct formation in the nucleoside-Pt compound system were studied by reversed-phase high-performance liquid chromatography [gradient 0-30% methanol in 30 min, ammonium acetate buffer (0.1 M) at pH 4.25] at fixed intervals of time and the product formation was examined by measuring the peak heights. After 10 h, the reaction was complete for guanosine and showed a steady state for adenosine. The increasing lipophilicity in the sequence of the platinum compounds resulted in a shift to longer retention times.

Adenosine↗