Determination of zinc by flow injection with fluorimetric detection in a micellar medium.

A room-temperature flow injection spectrofluorimetric method is presented for the determination of Zn(II), based on the use of salicylaldehyde thiocarbohydrazone in the presence of Triton X-100 and sodium acetate-acetic acid buffer. Various physical and chemical variables affecting the reaction in the flow system were evaluated. The proposed method is very selective. The calibration graph is linear over the range 10-1000 ng/ml, with a detection limit of 5 ng/ml and a relative standard deviation at the 50 ng/ml level of 1.8 %. The method was successfully applied to the determination of Zn(II) in drinking waters and biological samples.

Recent developments in derivative ultraviolet/visible absorption spectrophotometery.

The instrumental development and analytical applications of derivative ultraviolet/visible region absorption spectrophotometry produced in the last seven years (since 1987) are reviewed.

Evaluation of various N-phenylthiosemicarbazones as chromogenic reagents in spectrophotometric analysis.

The synthesis, physicochemical properties and interactions with metal ions of three new reagents of the N-phenylthiosemicarbazone family, namely pyridoxal phenylthiosemicarbazone, 3-hydroxypyridine-2-aldehyde phenylthiosemicarbazone and 2,6-diacetylpyridine bis(phenylthiosemicarbazone), as well as their ionization constants and the spectral features of their complexes with transition-element cations are reported. A photometric determination of cobalt with pyridoxal phenylthiosemicarbazone in perchloric acid medium is proposed and has been used in analysis of steels.

Derivative ultraviolet-visible region absorption spectrophotometry and its analytical applications.

Theoretical aspects, instrumental devices and analytical applications of derivative ultraviolet-visible region absorption spectrophotometry are reviewed.

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.