A. Navas

Synchronous scanning derivative spectrofluorimetry for the determination of cadmium with benzyl-2-pyridylketone 2-quinolylhydrazone

Abstract Synchronous scanning derivative spectrofluorimetry is used to determine cadmium by means of the fluorescent chelate formed with benzyl-2-pyridylketone 2-quinolylhydrazone at an apparent pH of 11 in 80% (v/v) ethanol. The normal spectrofluorimetric method is also described. The limits of detection are 0.7 and 4.1 ng Cd2+ ml−1, for the first derivative and normal techniques, respectively. Interferences in both methods are reported.

KINETIC FLUORIMETRIC DETERMINATION OF TRACES OF VANADIUM(V) BY MEANS -OF A CATALYSED AUTOXIDATION PROCESS

A kinetic method for determination of traces of vanadium(V) (0.04-0.5 ppm) is described. It is based on the catalytic action of vanadate in the autoxidation of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulphonate, giving rise to kinetic curves characterized by an induction period before the appearance of a product exhibiting an intense red fluorescence in acidic solution. This product has been investigated and the experimental variables and interferences have been studied.

Photometric and fluorimetric kinetic determination of manganese by means of the oxidation of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulphonate

Three kinetic methods for the determination of manganese, two of them by photometric monitoring and another by fluorimetric monitoring, based on the oxidation of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulphonate are described. A critical comparative evaluation of both monitoring techniques and their effect on the analytical figures of merit of the methods has been made. Manganese contents between 6.5 and 21.7 ng ml can be determined with relative standard deviation of +/- 3.7%. Under appropriate working conditions, the fluorimetric method can be satisfactorily applied to the determination of manganese in environmental samples of tap water and workroom metallic fumes.

Iron(III) as activator for catalytic fluorimetric microdetermination of V(V).

The activation of the vanadium(V)-catalysed aerial oxidation of sodium 4,8-diamino-1,5 -dihydroxyanthraquinone-2,6-disulphonate by iron(III) is discussed. The oxidation product is intensely fluorescent and allows fluorescence-monitoring of the slow reaction, which is preceded by an induction period. On the basis of this investigation, an accurate method for determination of vanadium(V) at the 1-10 ng/ml level has been developed.

Fluorimetric determination of iron(III) by a kinetic method

Abstract A sensitive and relatively interference-free method for the kinetic determination of iron(III) is described. The method is based on the catalytic action of this ion on the autoxidation process of 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulfonate (disodium salt), to produce a strong pink fluorescence that increases with time. The reaction is monitored at 585 nm, when excited at 525 nm, and the initial rate method is applied to perform the analytical procedure. The influence of reaction variables and the effect of foreign ions are discussed. Iron(III) contents between 0.1 and 1 μg ml −1 can be determined with R.S.D. of ± 3.7%.

Kinetic-fluorimetric determination of microamounts of cerium(IV) by means of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2,6-disulphonate

SummaryA 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 (λex=525nm,λem=585 nm), and allows determination of 0.02–0.37 ppm Ce(IV). The proposed method has few interferences.ZusammenfassungEine 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.

Benzyl 2-pyridyl ketone 2-pyridylhydrazone as reagent for the fluorimetric determination of zinc at ng/ml levels.

A sensitive fluorimetric method for the determination of zinc, based on the formation of a fluorescent chelate with benzyl 2-pyridyl ketone 2-pyridylhydrazone is described. In darkness, the fluorescence develops rapidly and remains stable for 1 hr. The detection limit is 15 ng/ml. The effect of reaction variables, and methods of removing interferences, are discussed.

Studies on ground and excited state prototropic equilibria of 2-fluorenaldehyde 2-pyridylhydrazone

Abstract The ground and excited state pK values of 2-fluorenaldehyde 2-pyridylhydrazone obtained from variations in fluorescence intensity with pH are reported. The two acid-base equilibria are separately treated by instrumental and chemical means. Absorption and fluorescence spectral shifts are employed to show that solute-solvent interactions through hydrogen-bonding are responsible for the disagreement between the excited state pK values obtained from Forster cycle calculations and from fluorimetric titration measurements.

Spectrofluorimetric Determination of Nanogram Amounts of Cadmium with Benzyl-2-Pyridylketone 2-Pyridylhydrazone

Abstract A rapid, simple and sensitive spectrofluorimetric determination of cadmium based on the formation of a fluorescent chelate with benzyl-2-pyridylketone 2-pyridylhydrazone is described. In d...

Coupled redox and complex formation processes as a kinetic fluorimetric method for the determination of cobalt

ZusammenfassungEine 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.SummaryA 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.