Probe 1, which contains an anilinopyridine chromophore and an azaoxa macrocyclic subunit, presented an absorption band centered at 340 nm in acetonitrile. Addition of Fe(III), Cr(III) and Hg(II) induced the growth of a new absorption band at 430 nm (with color change from colorless to yellow), whereas in the presence of Cu(II), Zn(II) and Pb(II), less marked changes were observed. The color changes observed upon addition of Fe(III), Cr(III) and Hg(II) were ascribed to the formation of 1:1 stoichiometry complexes with probe 1. Coordination of Fe(III), Cr(III) and Hg(II) with the pyridine fragment of 1 induced an enhancement of the charge transfer character accompanied with a marked bathochromic shift that was reflected in a color change from colorless to yellow. The strength of the interaction between probe 1 and Fe(III) cation was modulated upon interaction with anions. Of all the anions tested, only cyanide was able to induce the bleaching of the yellow 1·Fe(III) complex solution. This bleaching was ascribed to
the formation of 1·Fe(III)-CN complex that restored, to some extent, the optical features of the free probe allowing the chromogenic sensing of cyanide. Besides, 1·Fe(III) complex was used to detect
cyanide in acetonitrile-water 90:10 v/v mixtures with good recoveries.
Evaluation of methods for the analysis of soils according to § 8 of the German Federal Soil Protection Act (BBodSchG)
The German Federal Soil Protection Act establishes the conditions for effective soil protection and remediation of contaminated sites. In the German Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) limiting values and methods for the determination of environmentally harmful substances in soils are fixed. The aim of this project was to evaluate selected methods by comparative investigations and proficiency testing schemes. New methods for the determination of inorganic and organic pollutants should be developed and compared with the existing standard
methods. Despite the widespread use of ICP-OES up to now no national or international standard is available for the determination of heavy metals in soil extracts with this analytical method. The influence of spectral and non spectral interferences on the accuracy of the results was systematically investigated, especially based on aqua regia soil extracts. Analyte concentration equivalents were determined, too. Based on these results a proposal for a standard was submitted to the corresponding working group of ISO TC 190.[...]