Chromium speciation study in polluted waters using catalytic adsorptive stripping voltammetry and tangential flow filtration

The catalytic adsorptive stripping voltammetry (CAdSV) has been applied to physico-chemical chromium speciation study in the upper Dunajec catchment, severely polluted by the tannery wastewater. The method is based on the adsorptive preconcentration of the Cr(III)-diethylenetriammine-N,N,N',N'',N''-pentaacetic acid (DTPA) complex and the utilization of the catalytic reaction in the presence of nitrate. Under optimized conditions the CAdSV enables the oxidation state speciation study of Cr content by direct determination of Cr(VI) in the presence of the predominant Cr(III) concentration with the detection limit for chromium(VI) of 0.08nM and the linearity range from 0.1 to 80nM obtained for 20s of accumulation, as well as the determination of total Cr after UV oxidation of Cr(III) to Cr(VI). Due to the difference in the chemical properties of different chromium species the CAdSV method makes possible a speciation study of Cr(III) and Cr(VI) oxidation state. The RSD of the determination of Cr(VI) and Cr(III) varies from 0.5 to 5%. It has been proved that in natural water in which strong complexants of Cr(III) such a humid acids are presented, Cr(VI) can be determined accurately in the presence of high excess of Cr(III). Fractionation of selected water samples with tangential flow filtration (TFF, cut-off 10 and/or 1kDa) provides insight into physical Cr speciation, i.e. partitioning of the Cr(VI) and Cr(III) between the colloidal and the dissolved fractions. It has been shown that the content of the Cr species in the Dunajec river depends on the season, and is significantly higher in autumn and winter during the most intensive tanneries production processes. The concentration of total Cr exceeds occasionally the legally admissible level. A large fraction of total Cr(III) concentration is associated with the colloidal material, while Cr(VI) occurs solely in the truly dissolved form.

Pharmacokinetic interaction after joint administration of zinc and imipramine in forced swim test in mice

Recent preclinical and clinical data indicate beneficial role of zinc in the antidepressant treatment. To evaluate the mechanism of interaction between zinc and antidepressants, in the present study we examined the brain zinc, imipramine and desipramine concentrations in mice treated with combinations of zinc and imipramine and subjected to the forced swim test. We have chosen doses of zinc (10 mg/kg) and imipramine (15 mg/kg) which we have previously found to be ineffective in the forced swim test when given alone. However, when administered jointly, a significant reduction in the immobility time in this test was demonstrated. In the present study, we demonstrated a significant ca. 60% reduction in the brain desipramine and non-significant reduction (ca. 40%) in brain imipramine concentrations in the group of animals treated with zinc plus imipramine compared with animals treated with imipramine alone. The brain zinc concentration in the zinc plus imipramine group was reduced when compared with the group treated with zinc or imipramine alone. Since there was no increase in brain imipramine/desipramine or zinc brain concentration after combined zinc and imipramine treatment, the data suggest that pharmacodynamic rather than pharmacokinetic interaction between zinc and imipramine is responsible for behavioral effect in the forced swim test.