The use of a wavelength scanning technique for multi-element determinations by atomic fluorescence spectroscopy

Summary The simple modification necessary to a conventional atomic absorption spectrometer to enable it to be used for a wavelength scanning technique for multi-element atomic fluorescence determinations is described. Both a xenon arc lamp continuum and some dual-element electrodeless discharge lamps have been used as spectral sources. Results have been obtained for the rapid-sequential multi-element determination of several combinations of elements, and these show that the sensitivity and selectivity are the same by the scanning technique as by conventional atomic fluorescence.

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Wellenlängen-Scanning zur Multi-Elementbestimmung durch Atomfluorescenz-Spektroskopie

Zusammenfassung Eine einfache Modifikation eines konventionellen Atomabsorptions-Spektrometers wird beschrieben, die die Ausführung von atomfluorescenzspektrometrischen Bestimmungen mit Hilfe des Wellenlängen-Scanning gestattet. Als Lichtquellen dienen das Xenon-Bogenkontinuum sowie elektrodenlose Bielement-Entladungslampen. Die Ergebnisse der Bestimmung verschiedener Elementkombinationen zeigen, daß Empfindlichkeit und Selektivität der konventionellen Atomfluorescenzmethode entsprechen.

Lecture presented at Euroanalysis I Conference, 28. 8.–1, 9. 1972 in Heidelberg, Germany.     

Direct measurement of the counterion distribution within swollen polyelectrolyte films

The depth profile of the counterion concentration within thin polyelectrolyte films was measured in situ using contrast variant specular neutron reflectivity to characterize the initial swelling stage of the film dissolution. We find substantial counterion depletion near the substrate and enrichment near the periphery of the film extending into the solution. These observations challenge our understanding of the charge distribution in polyelectrolyte films and are important for understanding film dissolution in medical and technological applications.     

Influence of a water rinse on the structure and properties of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) films

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films exhibit a complex structure of interconnected conductive PEDOT domains in an insulating PSS matrix that controls their electrical properties. This structure is modified by a water rinse, which removes PSS with negligible PEDOT loss. Upon PSS removal, film thickness is reduced by 35%, conductivity is increased by 50%, and a prominent dielectric relaxation is eliminated. These results suggest that the removed PSS is not associated with PEDOT and that the conductive domain network is not substantially altered by the removal of a significant fraction of insulator. The removal of PSS may benefit organic light emitting diode fabrication by reducing acid attack on indium tin oxide electrodes and lead to more robust performance in switching circuits by extending the working frequency range.     

Nonacid cleavable detergents applied to MALDI mass spectrometry profiling of whole cells

Although cleavable detergents were first synthesized a number of years ago, they have only recently been successfully applied to problems involving biological molecules. Recent reports have demonstrated that these compounds are useful for applications involving both 2D PAGE and mass spectrometry. However, most cleavable surfactants have utilized acid-labile functional groups to affect cleavage. In applications where extreme pH is required, acid cleavable detergents have limited usefulness. We report the synthesis of fluoride cleavable silane compounds and photolabile cinnamate esters as cleavable detergents having alternative cleavage chemistries than previously reported cleavable detergents. These compounds were applied to whole cell analysis using MALDI mass spectrometry, and it was demonstrated that their use results in an increase in the number of proteins analyzed by increasing protein solubility.     

Duplex strand formation using alternating copolymers

The regular arrangement of complementary diaminopyridine-thymine (DAP-THY) on alternating copolymers permits cooperative binding events and the effective formation of well-controlled micrometre-scale aggregates.     

A general synthesis of tris-indole derivatives as potential iron chelators

The development of a novel route for the synthesis of a new class of compounds is described. The first tripodal, tris-indole amines are prepared by straightforward routes.