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  • 1
    Electronic Resource
    Electronic Resource
    Spectrofluorimetric and synchronous scanning first derivative spectrofluorimetry for determination of magnesium with salicylaldehyde 2-pyridylhydrazone (1984)
    s.l. : American Chemical Society
    Analytical chemistry 56 (1984), S. 2035-2038 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00276a013
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  • 2
    Electronic Resource
    Electronic Resource
    Enzymatic determination of fenitrothion by cholinesterase and acetylcholinesterase on fluorogenic substrates (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 958-961 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The action of the enzymes acetylcholinesterase and cholinesterase on the substrates indoxylacetate and 2-naphthyl acetate was studied kinetically. Both enzymes convert the substrates to highly fluorescent products (3-hydroxy-indole and 2-naphthol, respectively). The kinetic curves present the initial rate as the variation of fluorescence for a unity of time (ΔF/Δt) against the substrate concentration. This enzymatic reaction was investigated in presence of the inhibitor organophosphate pesticide fenitrothion. From the kinetic curves the enzymatic parameters and enzyme and substrate concentrations used for the calibration curve can be obtained. Four simple spectrofluorimetric methods for the enzymatic determination of fenitrothion were developed showing detection limits between 5.5 to 19.5 μmol/l, depending on the enzyme and the substrate used. The precisions (R.S.D.) of the methods were between 1.6 and 9.6%. A comparative study of the kinetic enzymatic parameters and the detection limits was performed. A good correlation was obtained between inhibition constants and the detection limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050281
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  • 3
    Electronic Resource
    Electronic Resource
    HPLC determination of tryptophan enantiomers with photometric, fluorimetric and diode-laser polarimetric detection (1996)
    Springer
    Chromatographia 42 (1996), S. 494-498 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Tryptophan ; Chiral separations ; Diode-laser polarimetric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The combined utilization of photometric, fluorimetric and polarimetric detection liquid chromatography detectors in series for the identification and quantification of D-tryptophan and L-tryptophan was evaluated. Detection limits of about 1 μg were established with the range of linearity extending to about 100 μg. The relative standard deviation of the D-form and L-form tryptophan were 7.32 and 4.22%, respectively. The amount unknown of tryptophan enantiomers in the different mixtures was determined with an accuracy of 1.58% at the 40 μg injection level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290282
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic-fluorimetric determination of microamounts of cerium(IV) by means of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulphonate (1982)
    Springer
    Microchimica acta 77 (1982), S. 175-181 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine kinetische Methode zur Bestimmung von Spuren Cer(IV) mit Hilfe von Natrium-4,8-diamino-1,5-dihydroxyanthrachinon-2,6-disulfonat wurde beschrieben. Dabei wird ein fluoreszierendes Oxydationsprodukt gebildet, das bei 525 nm angeregt mit einer maximalen Emission bei 585 nm fluoresziert. Die Reaktion ermöglicht die Bestimmung von 0,02–0,37 ppm Cer(IV). Die vorgeschlagene Methode wird nur durch wenige Störungen eingeschränkt.
    Notes: Summary A kinetic method for determination of traces of Ce(IV), based on the oxidation of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2, 6-disulphonate is described. The reaction is monitored by means of the fluorescence of the oxidation product (λ ex=525nm,λ em=585 nm), and allows determination of 0.02–0.37 ppm Ce(IV). The proposed method has few interferences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01237805
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  • 5
    Electronic Resource
    Electronic Resource
    Environmentally shifted fluorescence lifetimes for multicomponent phase-modulation fluorimetric analysis (1994)
    Springer
    Journal of fluorescence 4 (1994), S. 11-16 
    Details
    ISSN: 1573-4994
    Keywords: Fluorescence lifetimes ; solvent effects ; diuretic drugs ; simultaneous analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Several cyclodextrins, surfactants, and a series of three organic solvents-methanol, isoamylic alcohol, and hexanol-with different polarities and viscosities, were used to study the influence of the microenvironment on the fluorescent behavior of three diuretics-furosemide, triamterene, and piretanide. We concluded that on going from methanol to hexanol, the fluorescence lifetime of furosemide from 0.91 to 2.10 ns, that of triamterene from 4.54 to 4.44 ns, and that of piretanide from 5.24 to 10.37 ns. At 40 MHz, the phase shifts (excitation/emission) produced by furosemide, triamterene, and piretanide were 12.0, 29.6, and 30.2° in methanol and 27.8, 48.1, and 69.0° in hexanol. A three-factor, three-level factorial design allowed us to establish a calibration matrix of the three diuretics that covered the three ranges from 10 to 40, 1.5 to 6, and 0.1 to 0.4 μM for furosemide, piretanide, and triamterene, respectively. Data processing incorporated PLS adjustment values. The function was fitted to a phase-resolved fluorescence intensity at the three phase angles selected. Percentages recoveries were from 88 to 115%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01876649
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  • 6
    Electronic Resource
    Electronic Resource
    Synchronous scanning first and second derivative spectrofluorimetric determination of the alkaloid berberine (1986)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 323 (1986), S. 153-156 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Solvent effects on the spectral characteristics of berberine solutions and their influences on the sensitivity of its spectrofluorimetric determination are discussed. Linear calibration graphs in the ng·ml−1 range for zero, normal and synchronous first and second derivative are established. The prototropic behaviour of berberine in the ground and excited state was determined and related with the influence of proton motions in the analytical procedure. The influence of reaction variables, instrumental parameters and some interfering substances was studied. The application of the methods to synthetic mixtures is also described.
    Notes: Zusammenfassung Lösungsmitteleffekte auf die Spektralcharakteristik von Berberinlösungen und ihr Einfluß auf die Empfindlichkeit der spektrofluorimetrischen Bestimmung werden diskutiert. Lineare Eichkurven im ng/ml-Bereich wurden für die nullte, normale sowie synchrone erste und zweite Ableitung aufgestellt. Das prototrope Verhalten des Berberins im Grund- und angeregten Zustand wurde bestimmt und zum Einfluß der Protonbewegungen in der analytischen Methode in Bezug gesetzt. Der Einfluß der Reaktionsvariablen, der instrumenteilen Parameter sowie von störenden Substanzen wurde untersucht. Die Anwendung auf synthetische Mischungen wird beschrieben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01172909
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  • 7
    Electronic Resource
    Electronic Resource
    Coupled redox and complex formation processes as a kinetic fluorimetric method for the determination of cobalt (1983)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 315 (1983), S. 491-495 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A sensitive and relatively interference-free method for the kinetic determination of cobalt is described. The method is based on the slow oxidation of pyridin-2-aldehyde-2-pyridylhydrazone (PAPH) to a fluorescent product in the same medium as the complex formation with cobalt ions. The influence of reaction variables and the effect of foreign ions are discussed. Cobalt contents between 20 and 150 ng ml−1 can be determined with a relative standard deviation of 4%. The composition of the chelate species, and the stability constant of the complex have also been determined.
    Notes: Zusammenfassung Eine empfindliche und relativ störungsfreie Methode zur Cobaltbestimmung wird beschrieben. Sie beruht auf der langsamen Oxidation von Pyridin-2-aldehyd-2-pyridylhydrazon (PAPH) zu einem fluorescierenden Produkt und der Komplexbildung mit Cobaltionen in demselben Medium. Der Einflu\ von Reaktionsvariablen sowie von Fremdionen wird diskutiert. Cobaltgehalte von 20 bis 150 ng/ml können mit einer relativen Standardabweichung von 4% bestimmt werden. Die Zusammensetzung und StabilitÄtskonstante des Komplexes wurden ebenfalls bestimmt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493793
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  • 8
    Electronic Resource
    Electronic Resource
    Enhancement and inhibition of luminol chemiluminescence by phenolic acids (1995)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 10 (1995), S. 175-184 
    Details
    ISSN: 0884-3996
    Keywords: Luminol ; enhanced chemiluminescence ; phenolic acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We explored the behaviour of a series of phenolic acids used as enhancers or inhibitors of luminol chemiluminescence by three different methods to determine if behaviour was associated with phenolic acid structure and redox character. All the phenolic acids inhibited chemiluminescence when hexacyanoferrate(III) was reacted with the phenolic acids before adding luminol. The redox character of these compounds was clearly related to structure. When hexacyanoferrate(III)-luminol-O2 chemiluminescence was initiated by phenolic acid-luminol mixtures some phenolic acids behaved as enhancers of chemiluminescence, and others as inhibitors. We propose a mechanism to explain these findings. We found direct relationships between the redox character of the phenolic acids and the enhancement or inhibition of the chemiluminescence of the luminol-H2O2-peroxidase system and we propose mechanism to explain these phenomena.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170100306
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  • 9
    Electronic Resource
    Electronic Resource
    Phenol derivatives as enhancers and inhibitors of luminol-H2O2-horseradish peroxidase chemiluminescence (1998)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 75-84 
    Details
    ISSN: 0884-3996
    Keywords: luminol ; enhanced chemiluminescence ; phenol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Systematic studies on phenol derivatives facilitates an explanation of the enhancement or inhibition of the luminol-H2O2-horseradish peroxidase system chemiluminescence. Factors that govern the enhancement are the one-electron reduction potentials of the phenoxy radicals (PhO•/PhOH) vs. luminol radicals (L•/LH-) and the reaction rates of the phenol derivatives with the compounds of horseradish peroxidase (HRP-I and HRP-II). Only compounds with radicals with a similar or greater reduction potential than luminol at pH 8.5 (0.8 V) can act as enhancers. Radicals with reduction potentials lower than luminol behave in a different way, because they destroy luminol radicals and inhibit chemiluminescence. The relations between the reduction potential, reaction rates and the Hammett constant of the substituent in a phenol suggest that 4-substituted phenols with Hammett constants (σ) for their substituents similar or greater than 0.20 are enhancers of the luminol-H2O2-horseradish peroxidase chemiluminescence. In contrast, those phenols substituted in position 4 for substituents with Hammett constants (σ) lower than 0.20 are inhibitors of chemiluminescence. On the basis of these studies, the structure of possible new enhancers was predicted. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Assay of cholinesterase using a proenhancer of the luminol-H2O2-horseradish peroxidase reaction (1995)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 10 (1995), S. 285-289 
    Details
    ISSN: 0884-3996
    Keywords: Cholinesterase ; luminol ; pro-enhancer ; chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 2-Naphthyl acetate acts as a pro-enhancer of the luminol-H2O2-horseradish peroxidase reaction. Cholinesterase hydrolyses the bound acetyl group and produces 2-naphthol, and this compound is an enhancer of the chemiluminescent reaction. We studied the kinetics of chemiluminescent emission and the influence of 2-naphthyl acetate and cholinesterase enzyme concentration. The cholinesterase concentration versus chemiluminescence intensity maximum was linear for cholinesterase between 0 and 181 μU/mL, with a detection limit of 8 μU/mL and a relative standard deviation of 9.5% (n = 3), for a sample containing 90.67 μU/mL of cholinesterase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170100505
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