Investigations on immobilized porphyrine-derivates for the development of an optochemical sensor for the detection of lead-, cadmium- and mercury-ions in hydrous solutions. (Untersuchungen an immobilisierten Porphyrinderivaten zur Entwicklung eines optochemischen Sensors fuer die Bestimmung von Blei-, Cadmium- und Quecksilberionen in waessrigen Loesungen)

摘要

An optochemical sensor for the determination of the toxic heavy metal ions lead(II), cadmium(II) and mercury(II) in hydrous solutions was developed. The complexation reaction of bivalent metal ions with a porphyrine derivate (5,10,15,20-mesotetra (N-methylepyridyle) porphyrine-iodid, TMPyP), which causes changes in the absorbance spectra, was used for the detection. The spectral changes correlate with the given metal concentration and they are specific for each cation. The reaction of the three cations with TMPyP was investigated and characterized both in solution and in immobilized state. The dye was immobilized in a porous glasslike matrix which was coated on a glass support by the sol-gel method. The calibration for the single components showed detection limits of 10(sup -7) mol/l respectively, corresponding to 20 (mu)g/l for (Pb)II, 11 (mu)g/l for Cd(II) and 20 (mu)g/l for Hg(II). The reproducibility of the measured signals layed in the range of 10%. By using a chemometrical evaluation method, the Partial Least Square- (PLS-) algorithm, it was possible to determine the concentrations of binary and ternary mixtures of Pb(II), Cd(II) and Hg(II) in the range from 10(sup -7) to 10(sup -5) mol/l. These investigations were made as well in solution as in sensors. Summing up, it may be said that it was succeeded to detect the three environmental relevant cations lead(II), cadmium(II) and mercury(II) separately and simultaneously with an optochemical sensor. Because of the obtained detection limits for the single cations it could be possible to use these sensors for waste water monitoring. The limits which should be controlled could be measured by the sensor with sufficient certainty. (orig./SR)