21 October 1994 Detection of toxic metal ions with near-infrared compounds
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The determination of toxic metal ions in water using near-infrared compounds synthesized in our laboratories will be reported. Several near-infrared tetrasubstituted chloroaluminum 2,3-naphthalocyanine derivatives with spectral characteristics (absorbance and fluorescence) between 700 nm and 1000 nm have been used in these investigations. In the presence of metal ions the NIR dye's absorbance maximum undergoes a bathochromic shift of about 25 nm accompanied by changes in the fluorescence spectra along with molecular lifetime. The response of the NIR dye in the presence of several concentrations of toxic metal ions will be reported. The fluorescence intensity generated by the complex formed by the metal ion and the dye was monitored by (a) a modified commercially available spectrofluorometer and (b) an NIR instrument developed in our laboratories. The fluorescence intensity changes measured with the probe in the presence of metal ions can be used to construct a calibration curve for the monitoring of contaminants' metal ions in the environment. The effect of metal ions on the lifetime of the NIR dye as compared to the uncomplexed dye will be reported. The NIR instrument consists of a semiconductor laser diode, the NIR dye and a detector. The output wavelength of a 780 nm diode (used as the excitation source) matched the absorbance of these dyes and improved the detection limits of the analytes. Long term stability of the probe was investigated by a week-long period of observation. After one week the intensity varies by only 2%, suggesting suitably for long storage.
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Guillermo A. Casay, Guillermo A. Casay, Tibor Czuppon, Tibor Czuppon, Lawrence Evans, Lawrence Evans, Gabor Patonay, Gabor Patonay, "Detection of toxic metal ions with near-infrared compounds", Proc. SPIE 2293, Chemical, Biochemical, and Environmental Fiber Sensors VI, (21 October 1994); doi: 10.1117/12.190975; https://doi.org/10.1117/12.190975


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