Pesticides monitoring in water using laser-induced fluorescence and absorption techniques

Mihail-Lucian Pascu; Doina Cristu; Aurelia Vasile; N. Moise

doi:10.1117/12.203507

8 March 1995 Pesticide monitoring in water using laser-induced fluorescence and absorption techniques

Mihail-Lucian Pascu, Doina Cristu, Aurelia Vasile, N. Moise

Proceedings Volume 2461, ROMOPTO '94: Fourth Conference in Optics; (1995) https://doi.org/10.1117/12.203507
Event: ROMOPTO '94: 4th Conference on Optics, 1994, Bucharest, Romania

Abstract

Experimental techniques to monitor pesticides at low concentrations using absorption, laser induced fluorescence (LIF) and fluorescence lifetime measurements are reported. Since absorption spectra of chlortriasine samples in water are showing significant peaks in UV range at 224 nm and 260 nm, laser monitoring of chemically untreated samples is difficult due to the lack of tunable laser radiation available in this spectral range. Consequently, chlortriasines were complexed with pyridine and ethyl ester of cyanacetic acid in basic medium to be identified in the visible range. To obtain absorption spectra of the complexes (at chlortriasines concentration of some ppm), a nitrogen laser pumped tunable dye laser was used and an absorption maximum at 545.5 nm was measured. To measure the fluorescence spectra of the same complex the excitation was made at 530 nm; chlortriasines concentration range was between 5 ppm and 20 ppm and the fluorescence maximum was obtained at 577.2 nm. Fluorescence lifetime measurements performed on complexed chlortriasines using a 700 psec nitrogen pulsed laser, have shown a value of 2.6 nsec with an error of 6%. Time evolution of the LIF spectra and fluorescence lifetime has shown that the fluorescence peak emitted by the complex is shifted after 24 hours from 577 nm to 428 nm in direct connection with the modification of the excitation wavelength from 520 nm to 337.1 nm; in the same time the fluorescence lifetime increases in 24 hours to 6.6 nsec.

Citation Download Citation

Mihail-Lucian Pascu, Doina Cristu, Aurelia Vasile, and N. Moise "Pesticide monitoring in water using laser-induced fluorescence and absorption techniques", Proc. SPIE 2461, ROMOPTO '94: Fourth Conference in Optics, (8 March 1995); https://doi.org/10.1117/12.203507

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