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  • 11
    Electronic Resource
    Electronic Resource
    Two-phase buffer systems: theoretical considerations (1978)
    s.l. : American Chemical Society
    Analytical chemistry 50 (1978), S. 597-600 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50026a014
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  • 12
    Electronic Resource
    Electronic Resource
    Flow injection gas-diffusion method for preconcentration and determination of trace sulfide (1988)
    s.l. : American Chemical Society
    Analytical chemistry 60 (1988), S. 2791-2796 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00175a030
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  • 13
    Electronic Resource
    Electronic Resource
    Determination of the mechanism of the chlorination of gold in aqueous solutions (1990)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 29 (1990), S. 1696-1700 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00104a019
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  • 14
    Electronic Resource
    Electronic Resource
    Photocatalytic oxidation of aqueous ammonia (ammonium ion) to nitrite or nitrate at TiO2 particles (1992)
    Springer
    Monatshefte für Chemie 123 (1992), S. 333-339 
    Details
    ISSN: 1434-4475
    Keywords: Ammonia ; Nitrate ; Oxidation ; Photocatalysis ; Titanium(IV) oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde die photokatalytische Oxidation von Ammoniak (Ammoniumion) mittels Luft oder reinem Sauerstoff an Titan(IV)oxid-Pulveroberflächen unter Induktion von UV-Licht untersucht. Die experimentellen Bedingungen wurden variiert, wobei der Effekt despH-Wertes, des Spülgases und sowohl die Ammoniak- als auch die Photokatalysator-Konzentration berücksichtigt wurde. Dabei ergab sich, daß das Hauptprodukt der photokatalytischen Oxidation vompH abhängt und entweder Nitrit oder Nitrat ist. Ein Gasdiffusions-Fließinjektions-Analysensystem wurde zur on-line-Kontrolle der Ammoniak-Konzentration verwendet. Off-line-Ionenchromatographie mit UV-Detektion wurde zur Konzentrationsbestimmung für Nitrit und Nitrat herangezogen. Die Verwendung von Photokatalysatoren wie Titanoxid könnte sich als gangbarer Weg erweisen, um Ammoniak (Ammoniumion) entweder zu Nitrit oder zu Nitrat umzusetzen.
    Notes: Summary The photocatalytic oxidation of ammonia (ammonium ion) in the presence of air or pure oxygen at titanium(IV) oxide powder surfaces and induced by UV light was investigated. Experimental conditions were varied and the effect ofpH, sparging gas, as well as the concentration of both ammonia (ammonium ion) and photocatalyst were investigated. It has been established that the principal product of photocatalytic oxidation depends onpH, and is either nitrite or nitrate. A gas-diffusion flow injection analysis system with conductivity detection was used for on-line monitoring of ammonia concentration. In addition, ion-chromatography with UV detection was utilized for offline monitoring of nitrite and nitrate concentrations. The use of a photocatalyst such as TiO2 may prove to be a viable method for conversion of ammonia (ammonium ion) to either nitrite or nitrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810945
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  • 15
    Electronic Resource
    Electronic Resource
    Simultaneous determination of chromium(VI) and chromium(III) by flame atomic absorption spectrometry with a chelating ion-exchange flow injection system (1985)
    Springer
    Microchimica acta 87 (1985), S. 353-360 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Simultaneous Determination of Chromium(VI) and Chromium(III) by Flame Atomic Absorption Spectrometry with a Chelating Ion-Exchange Flow Injection System A simple method is described for the simultaneous determination of chromium(VI) and chromium(III) in a flow injection system comprising chelating ion-exchange and flame atomic absorption spectrometry. Sampling rates for 200μ1 and 1 ml sample volumes were 120 and 60 h−1 (240 and 120 speciations per hour), respectively. Typical relative standard deviations were 0.52% for Cr(VI) (0.50μg ml−1 and 0.67% for Cr(III) (0.10,μg ml−1) and the corresponding limits of detection were 85 ng ml−1, and 16 ng ml−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01196834
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  • 16
    Electronic Resource
    Electronic Resource
    Determination of acidic constants of some phenyl-hydroxyiminoethyl quinolinium compounds (1986)
    Springer
    Monatshefte für Chemie 117 (1986), S. 661-670 
    Details
    ISSN: 1434-4475
    Keywords: Acidic constants ; Potential antidotes ; Quinolinium oximes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Mischaciditätskonstanten (pK′ a ) der Chinolin-Oxime 1-(2-Phenyl-2-hydroxyiminoethyl)-1-chinolinium chlorid (F-1), 1-(2-Phenyl-2-hydroxyiminoethyl)-1-isochinolium chlorid (F-2), 1-(2-Phenyl-2-hydroxyiminoethyl)-1-(4′-methyl)-chinolinium chlorid (F-3) und 1-(2-Phenyl-2-hydroxyiminoethyl)-1-(6′-methyl)-chinolinium chlorid (F-4) wurden durch ihre UV-Absorptionspektren in einer Reihe vonBritton-Robinson-Pufferlösungen impH-Intervall 8.74–11.28 (t=25±0.5°C; μ=0.2) bestimmt. Die berechnetenpK a -Werte stimmen mit den über graphische Methoden erhaltenen Ergebnissen überein. DerpK′ a -Wert beträgt 9.93 für die VerbindungF-1 und 9.90 fürF-2, sowie 10.02 fürF-3 andF-4. Auf Grund der potentiometrischen Titration wurden auch die thermodynamischen Aciditätskonstanten (pK a ) berechnet: 9.82 fürF-1, 9.71 fürF-2, 9.91 fürF-3 und 9.86 fürF-4. Wenn man diese Konstanten in Mischaciditätskonstanten überträgt, erhält man Werte, die mit den durch spektrophotometrischen Bestimmungen erhaltenen Werten gut übereinstimmen.
    Notes: Abstract Mixed acidic constants (pK′ a ) of quinolinium oximes [1-(2-phenyl-2-hydroxyiminoethyl)-1-quinolinium chloride (F-1), 1-(2-phenyl-2-hydroxyiminoethyl)-1-isoquinolinium chloride (F-2), 1-(2-phenyl-2-hydroxyiminoethyl)-1-(4′-methyl)-quinolinium chloride (F-3), and 1-(2-phenyl-2-hydroxyiminoethyl)-1-(6′-methyl)-quinolinium chloride (F-4)] have been determined via their UV absorption spectra recorded in the series ofBritton-Robinson's buffer solutions in thepH region 8.74–11.28 (t=25±0.5°C, μ=0.2). The obtainedpK′ a values are in good agreement with those achieved by applying graphical methods. The followingpK′ a values have been obtained: 9.93 forF-1, 9.90 forF-2, and 10.02 forF-3 andF-4. On the basis of potentiometric titrations thermodynamic acidic constants (pK a ) of compoundsF-1,F-2,F-3, andF-4 have been determined and they were found to be 9.82, 9.71, 9.91, and 9.86, respectively. The values obtained by transferringpK a intopK′ a are in good agreement with the values obtained spectrophotometrically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00817903
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  • 17
    Electronic Resource
    Electronic Resource
    Indirect determination of bromide by diffusion flow injection analysis with amperometric detection (1992)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 342 (1992), S. 98-102 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid, indirect diffusion flow injection analysis (FIA) method with amperometric detection has been developed for the selective and sensitive determination of Br−. The method is based on permanganate oxidation of Br− to bromine. Bromine diffuses through a PTFE membrane and is quantified amperometrically at a platinum working electrode. Calibration graphs were linear up to the maximum concentration of Br− investigated (10.0 mmol/l). The precision of the technique was better than a relative standard deviation of 0.7% at 10.0 μmol/l, with a throughput of 30 samples per hour. The effects of temperature, acidity, working potential, composition of the reagent solution and interferents on the FIA signals were studied. The catalytic effect of Cl− on the permanganate oxidation of the analyte was utilized to lower the detection limit to 1 μmol/l (16 ng Br−). Similar detection limits were achieved by combining the effects of higher acidity (4.0 mol/l H2SO4) and elevated temperatures (40°C). The method was successfully applied to the determination of Br− in chloride and other reagents, as well as in natural waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321701
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  • 18
    Electronic Resource
    Electronic Resource
    Simultaneous flow injection speciation of iron(II) and iron(III) cyano complexes utilizing electrochemical and atomic absorption detectors in series (1988)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 330 (1988), S. 614-618 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the simultaneous speciation of Fe(CN) 6 4− and Fe(CN) 6 3− in a flow injection (FIA) system comprising electrochemical (EC) and flame atomic absorption spectrometry (AAS) detectors in series. One of these species is detected amperometrically at a Pt-electrode by applying the required potential and measuring the resulting reduction or oxidation current of the appropriate iron cyanide complex. Total iron in both species is determined by an AAS detector. The EC detector is inherently more sensitive, with a detection limit of 0.5 Μg Fe l−1 and a relative standard deviation of 1.0% for a 0.040 Μg Fe ml−1 sample. The limit of detection for the AAS detector is 0.5 Μg Fe ml−1, and the relative standard deviation for a 5.70 Μg Fe ml−1 sample is 0.40%. The method enables up to 60 analyses (120 speciations) per hour and obviates the problem of easy oxidation of Fe(CN) 6 4− .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00473778
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