The distribution of chromium between soil and leachate was monitored. The natural process of percolation of rainwater through soil was simulated under laboratory conditions and studied by column ...leaching extraction. Migration of chromium in soil is conditioned by the level of chromium soil contamination, the organic matter content in the soil and rainwat eracidity. Chromium(III) and chromium(VI) were determined by a spectrophotometric method with diphenylcarbazide in acidic media. Comparing the results of chromium speciation in the leachate obtained by experimental model systems and geochemical modelling calculations using the Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influences of pH and soil organic matter content were in compliance after their experimental and the oretical definition. The Stockholm humic model used to evaluate the leaching results corresponded rather well with the measured values.
Rutin (quercetin-3-O-rutinoside) is one of the most abundant bioflavonoids with various biological and pharmacological activities. Considering the ubiquitous presence of Mg(II) and Ca(II) ions in ...biological systems we decided to investigate their influence on the autoxidation of rutin in weakly alkaline aqueous solutions. Changes in UV-Vis spectra recorded during the rutin autoxidation in aqueous solution at pH 8.4 revealed that this process was very slow in the absence of metal ions. The presence of Mg(II) and, especially Ca(II) ion, increased the transformation rate of rutin. UV-Vis spectra recorded after prolonged autoxidation indicated the formation of humic acidlike products in the presence of Mg(II) and Ca(II) ions. Four new compounds formed during the initial stage of rutin autoxidation in the presence of Mg(II) and Ca(II) ions were detected by HPLCDAD. Based on the analysis of their DAD UV-Vis spectra and comparison of their retention times with the retention time value for rutin, we concluded that the initial rutin transformation products were formed by the water addition on double bond in ring C and hydroxylation of ring B. A very small decrease of the initial rutin concentration (4%) was observed by HPLC-DAD in the absence of metal ions for the period of 90 minutes. However, rutin concentration decrease was much larger in the presence of Mg(II) and Ca(II) ions (14% and 24%, respectively). The more pronounced effect of Ca(II) ion on the rutin autoxidation may be explained by the stronger binding of Mg(II) ion to rutin and thus greater stabilizing effect on reaction intermediates caused by its higher ionic potential (charge/ionic radius ratio) in comparison to Ca(II) ion. The results of this study may contribute to the better understanding of interactions of Mg(II) and Ca(II) ions with natural phenolic antioxidants which are important for their various biological activities.
Multivariate curve resolution — alternating least squares (MCR-ALS) has been applied to data collected from UV/Vis spectrophotometric analysis of the autoxidation process of pyrogallol in weakly ...alkaline aqueous solutions. The MCR-ALS analysis was able to explain the autoxidation kinetics of pyrogallol at pH 7.4 and 8.0, allowing deduction of the pure spectra and concentration changes of different species present throughout the entire process. The autoxidation process at pH 7.4 was found to follow a first-order reaction model, with formation of purpurogallin as the sole and terminal product. Changing the pH to 8.0 not only accelerated autoxidation of pyrogallol to purpurogallin but also introduced a further autoxidation of purpurogallin. At pH 8.0 the process fits a model of two consecutive first-order reactions. The first step is formation of purpurogallin, which reacts in a further autoxidation to form a yellow colored substance, most probably purpurogallin polymer.
Lipoic acid was shown to largely decrease the production of malondialdehyde in copper intoxicated rats. FTIR spectroscopy and ESI-MS were used to clarify the mechanisms of this beneficial effect by ...investigating Cu(II) ion-lipoic acid interactions in model systems. Display omitted
The effect of lipoic acid (LA) supplementation to Cu(II) ion intoxicated rats was investigated by measuring the level of malondialdehyde (MDA), a common marker for oxidative stress, in liver and kidney tissues. Significant decrease of MDA was achieved by LA administration to rats one day after Cu(II) ion intoxication thus proving that LA can have beneficial effects in the case of heavy metals intoxication. FTIR spectroscopy and ESI-MS were used to investigate molecular mechanisms of Cu(II) ion–ligand interactions in model systems containing LA or its reduced form DHLA at milimolar and micromolar levels, respectively. FTIR spectra revealed that LA behaves as a monodentate ligand while DHLA behaves as a bidentate ligand in interaction with Cu(II) ion. ESI-MS revealed that there was direct interaction of LA with Cu(II) ions even at the micromolar level.
The complexation of humic acid with certain heavy metal ions (Co(II), Ni(II),
Cu(II), Zn(II) and Pb(II)) was investigated. The stability constants of
humate complexes were determined by method which ...is based on distribution of
metal ions between solution and resin in the presence and the absence of
ligand, known as Schubert?s ion exchange method. Experiments were performed
at 25 ?C, at pH 4.0 and ionic strength of 0.01 mol dm-3. It was found that
the 1:1 complexes were formed between metal ions and humic acid. Obtained
results of the stability constants, log ?mn, of complexes formed between the
metal ions and humic acid follow the order Co(II) < Ni(II) < Cu(II) > Zn(II)
which is the same like in the Irving-Williams series for the binding strength
of divalent metal ion complexes. Stability constant of complex between Pb(II)
ions and humic acid is greater than stability constants of other investigated
metal-humate complexes. The investigation of interaction between heavy metal
ions and humics is important for the prediction of the distribution and
control of the migration of heavy metals in natural environment.
•Osteoporosis is induced by glucocorticoids in Wistar rats during a twelve week period of time.•FTIR results demonstrated that the composition of mandibular bone tissue was changed.•In recovery and ...treatment phase the increase of mineral content was statistically significant.
The influence of glucocorticoids on the composition and mineral/organic content of the mandible in tested animals after recovery and healing phase was investigated in this work. The results of FTIR analysis demonstrated that bone tissue composition was changed after glucocorticoid treatment. The increase of calcium, magnesium, phosphorus content and mineral part of bones was statistically significant in recovery phase and in treatment phase that included calcitonin and thymus extract. Some changes also happened in the organic part of the matrix, as indicated by intensity changes for already present IR bands and the appearance of new IR bands in the region 3500–1300cm−1.
This paper outlines the changes in the mineral tissue of teeth that had been exposed to the influence of the agents of natural media. Such mineral tissue could be used as a potentially important ...forensic material that is gradually altered under the influence of external media. The biometal content was determined using the ICP-OES technique. According to the quantitative changes of the biometals in teeth tissue after its exposure to different media, the migration of Ca super(2+), Mg super(2+), Fe super(2+), Cu super(2+) and Zn super(2+) in teeth-soil and teeth-water media was observed. The content of Ca super(2+) and Mg super(2+) in the mineral tissue increased, but the Cu super(2+) content decreased. The migration of Fe super(2+) and Zn super(2+) depended on the content and type of the soil media and differed for clay soil, limestone enriched soil and urban area soil. The changes that occurred in the mineral matrix of teeth were detected by the SEM-EDS technique. The intensity of the biometal content and the mineral matrix changes are a potentially significant subject matter for forensic examination, because they indicate the kind of medium to which the material was exposed.
A method for the determination of soluble lead in human teeth by potentiometric stripping analysis with constant inverse current in the analytic step (PSA-
i
R), is described. The metal ions were ...concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. This paper examined effect of various factors on the PSA-
i
R results including the electrolysis potential, the solution stirring rate, and the constant inverse current. Quantitative analysis was carried out by both standard addition and calibration curve methods; a good linearity was obtained in the concentration range from 5 to 25
μg/dm
3. A detection limit of 0.64
μg/dm
3 was obtained, with a 5.21% coefficient of variation. Results obtained for teeth were not significantly different from these obtained by flameless atomic absorption spectrophotometry (FAAS).
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