Jürgen Mattusch

Sorption on natural solids for arsenic removal

Steady state experiments were conducted on arsenic sorption from aqueous solutions by natural solids to test the feasibility of these materials to act as concentrator for arsenic removal from groundwater and drinking water. The solids considered were natural zeolites, volcanic stone, and the cactaceous powder CACMM. The arsenic species studied were As(III), As(V), dimethylarsinic acid (DMA) and phenylarsonic acid (PHA). The arsenic removed was determined from the data obtained by measuring the concentration diminution of the arsenic species in the liquid phase at equilibrium before and after the adsorption experiment by means of ICP-AES for the total concentration of arsenic and IC-ICP-MS to determine the arsenic species. The latter method allowed the detection of As(V) additionally formed as a result of the oxidation of As(III) on some of the zeolites. The sorption of the arsenic species onto zeolites was studied on both non-activated and activated zeolites, as well as on zeolites hydrogenated or modified with iron, and with respect to varying pH. The kinetics and the ability to desorb and readsorb the arsenic species were investigated for selected zeolites.

Determination of Anionic, Neutral, and Cationic Species of Arsenic by Ion Chromatography with ICPMS Detection in Environmental Samples.

Ion chromatographic methods developed to separate either cationic, neutral, and anionic arsenic species or soluble and suspended arsenic species were successfully used in DORM-2 standard reference material and in water samples of environmental interest. The most effective separation of the analytes within 10 min was achieved with a nitric acid gradient elution using a strong anion-exchange stationary phase with additional capacity for hydrophobic interactions (IonPac AS7). The elemental-specific detection mode allows the sensitive determination of the arsenic species in the submicrogram per liter range. The calibration results were compared with those obtained by an alkaline water-methanol mixed eluent combined with a weak anion-exchange column (IonPac AS4A-SC). Differences in sensitivities were eclipsed by the low level of the baseline and the noise when using nitric acid. The gradient method was used to determine arsenic species in highly ferrous/ferric-contaminated leachates of lignite spoil. The companion elements underwent parallel screening to explain the interactions of arsenic species with the major elements.

Uptake of arsenite and arsenate by clinoptilolite-rich tuffs

Abstract Clinoptilolite-containing rocks were used to study the possible uptake of arsenite (H 3 AsO 3 ) and arsenate (H 2 AsO 4 − ) species from aqueous solution. Two samples also exhibited mordenite and erionite zeolitic phases. Batch and isotherm studies at pH 4 in the concentration range 0.1 −1 were performed. The experimental data were used to model Freundlich, Langmuir and Langmuir–Freundlich adsorption isotherms. Solutions were analyzed by means of ion chromatography coupled with inductively coupled plasma mass spectrometric detection (IC-ICP-MS). All zeolitic samples investigated removed more H 2 AsO 4 − than H 3 AsO 3 at equivalent arsenic concentrations. Although the saturation capacity of the tuffs studied was inversely related to the silicium dioxide content and directly to the iron content in the acid-washed zeolite, the addition of iron did not significantly improve the removal efficiency. Up to 98% of H 3 AsO 3 were removed from a 500 μg As l −1 solution by three of the samples studied after a contact time of 70 days.

Voltammetric Detection of the DNA Interaction with Copper Complex Compounds and Damage to DNA

Binding reactions of copper(II) complexes of 1,10-phenanthroline (phen) and tetraaza macrocyclic ligand TAAB with calf thymus DNA have been investigated voltammetrically at bare and DNA modified glassy carbon electrodes. The values of binding constant, binding site size, ratio of binding constants for the reduced and oxidized copper complex forms as well as information on the electrostatic and intercalative binding modes were obtained by solution and surface-based methods. The Cu(phen)22+complex mediates the dsDNA cleavage to a higher degree than Cu(TAAB)2+as indicated by the redox marker Co(phen)33+and the anodic signal of the DNA base. A procedure for the damage to DNA detection using dsDNA/GCE biosensor is proposed.

Model experiments on the microbial removal of chromium from contaminated groundwater.

A bacterial consortium with representatives of sulfate-reducing and denitrifying bacteria was selectively enriched. Model experiments under microaerobic conditions showed that it precipitated chromium from Cr (VI)-containing waters (area of a former electroplating factory, Leipzig, Germany) by two different mechanisms: by sulfate reduction and precipitation as sulfide, and by some direct reduction. Sulfate reduction needed fatty acids as organic substrates and resulted at the first stage in no sulfide accumulation. In the absence of the fatty acids but with straw as organic substrate, the direct reduction of chromium was observed without sulfate reduction. In this case Cr (VI)-reduction rate correlated with that of the denitrification.

Determination of gadolinium in river water by SPE preconcentration and ICP-MS

An analytical scheme was developed for the determination of Gd-diethylenetriaminepentaacetate (Gd-DTPA), Gd and the other rare earth elements (REE) in river water by inductively coupled plasma (quadrupole) mass spectrometry (ICP-Q-MS). The preconcentration step was essential, since the limits of detection of this multielemental analytical technique are higher than the trace concentrations of the interesting elements in river water. Solid phase extraction (SPE) with different commercially available complexing agents (Chelex 100, Toyopearl and ethylhexylphosphates) was employed for the preconcentration of REE. The investigations revealed that complex stability (varying in dependence of the pH value) has a strong influence on the degree of the enrichment of Gd-DTPA. Based on acidified water samples (pH<3) a procedure using ethylhexylphosphates was proposed for the preconcentration of Gd and REE from surface water samples. For this purpose C(18)-cartridges loaded with ethylhexylphosphates were used, resulting in an enrichment factor of 40.

Evaluation of extraction procedures for the ion chromatographic determination of arsenic species in plant materials

The determination of arsenic species in plants grown on contaminated sediments and soils is important in order to understand the uptake, transfer and accumulation processes of arsenic. For the separation and detection of arsenic species, hyphenated techniques can be applied successfully in many cases. A lack of investigations exists in the handling (e.g., sampling, pre-treatment and extraction) of redox- and chemically labile arsenic species prior to analysis. This paper presents an application of pressurized liquid extraction (PLE) using water as the solvent for the effective extraction of arsenic species from freshly harvested plants. The method was optimized with respect to extraction time, number of extraction steps and temperature. The thermal stability of the inorganic and organic arsenic species under PLE conditions (60-180 degrees C) was tested. The adaptation of the proposed extraction method to freeze-dried, fine-grained material was limited because of the insufficient reproducibility in some cases.

Accelerated fractionation of heavy metals in contaminated soils and sediments using rotating coiled columns

A new approach to performing an accelerated sequential extraction of trace elements from solid samples has been proposed. It has been shown that rotating coiled columns (RCC) earlier used in counter-current chromatography can be successfully applied to the dynamic leaching of heavy metals from soils and sediments. A solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while different eluents (aqueous solutions of complexing reagents, mineral salts and acids) were continuously pumped through. The procedure developed is time saving and requires only 4-5 h instead of the several days needed for traditional sequential extraction (TSE), complete automation being possible. Losses of solid sample are minimal. In most cases the recoveries of readily bioavailable and leachable forms of Pb, Zn, and Cd are higher, if a dynamic extraction in RCC is used. Since naturally occurring processes are always dynamic, continuous extraction in RCC may help to estimate the contents of leachable forms and their potential risk for the environment more correctly than batch TSE. The Kersten-Foerstner and McLaren-Crawford leaching schemes have been compared, the former has been found to be preferable.

Detection of arsenic-containing hydrocarbons in canned cod liver tissue

Arsenic is a metalloid well known to be potentially toxic depending of its species. Lipid-soluble arsenicals (arsenolipids) are present in a wide range of biological samples in which they could play a role in the biosynthesis of organoarsenic compounds from inorganic arsenic compounds. Arsenolipids have recently attracted considerable interest. In order to gain deeper insights into the impact of arsenolipids new analytical approaches for reliable determination of this class of arsenic-containing hydrocarbons in various matrices are needed. High concentrations of arsenolipids were found in seafood which served as sample material in this study. We report the investigation of three arsenolipids found in canned cod liver from which they were extracted and purified by solid phase extraction (SPE) using a silica gel column and ethyl acetate/methanol as eluent. Analytical studies were conducted by means of gas chromatography coupled with ICP-MS, MIP-AES and EI-qMS and by TOF-MS. The results obtained by GC-ICP-MS and GC-MIP-AES showed the existence of numerous arsenic compounds in the SPE fractions collected. Three major peaks were found within a retention time window between 10 and 25 min. The presence of arsenic compounds in the fish tissue could be confirmed using GC-EI-qMS analysis. Corresponding information of the molecular weights of the major arsenic species were provided by TOF-MS which allows highly accurate mass determinations. The results showed the presence of the arsenic-containing hydrocarbons with the following molecular formulas: C(17)H(37)AsO (calculated for [M+H](+) 333.2133; found 333.2136; Deltam=0.90 ppm); C(19)H(41)AsO (calculated for [M+H](+) 361.2446; found 361.2446; Deltam=0.00 ppm); C(23)H(37)AsO (calculated for [M+H](+) 405.2133; found 405.2145; Deltam=2.96 ppm). Suggestions for the corresponding structures are discussed.

Application of natural zeolites for preconcentration of arsenic species in water samples.

Zeolites of the clinoptilolite type produced in Mexico and Hungary were investigated with respect to their sorption efficiency for various redox species of arsenic. Long-term experiments showed that arsenate remains stable for a long period in spiked deionised water and drinking water, as well as in the surface water of the Biela valley in Saxony, Germany. Both clinoptilolites are able to decrease the initial arsenic concentration of 200 microg l(-1) by more than 75% in deionised, drinking, ground and surface waters. In the case of the Mexican zeolite, both the arsenite and the arsenate concentrations (200 microg l(-1)) can be lowered from 200 microg l(-1) to 10 microg l(-1), which is the World Health Organisations (WHOs) recommended maximum level. It was found that the presence of cations and anions in the natural waters of Biela, Germany, and Zimapán, Mexico, did not reduce the efficiency of the selected zeolites. The Hungarian zeolite removed 75% of the arsenate in the Zimapán water and only 50% when the sample was first acidified. This zeolite totally desorbed the fixed arsenic into a water volume that was half the volume in the adsorption experiment.