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A controlled environment system, termed the Phyto-Nutri-Tron (PNT), has been established to study whole plant ecophysiological responses to multiple environmental factors. The PNT is a computer-controlled highly flexible growth facility with independent control of the shoot and the root environment. The facility consists of two growth cabinets each containing four separate hydroponic growth systems. The growth cabinets can be used as assimilation chambers with individual control of temperature, humidity, light, CO2 and monitoring of O2. The hydroponic growth systems are connected to nutrient supply units with disinfection systems and individual control of temperature, pH and oxygen. The ionic composition of the solutions has automated feedback control through a PO4 autoanalyzer and a flow injection analyzer which also analyzes NH4+, NO2- and NO3-. Other ions are automatically monitored by ICP-AES. The system has automated calibration procedures of the analytical equipment and prolonged studies of plant growth can be performed under constant environmental conditions. This paper describes the design and construction of the PNT, the results of a number of tests showing the degree of control of environmental factors and the results of a comparative study on NH4+ and NO3- uptake kinetics by Juncus effusus conducted in the PNT demonstrate the use of the PNT in ecophysiological studies.
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PMID:Design and performance of the Phyto-Nutri-Tron: a system for controlling the root and shoot environment for whole-plant ecophysiological studies. 1154 49

The cardiovascular system is currently considered a target for particulate matter, especially for ultrafine particles. In addition to autonomic or cytokine mediated effects, the direct interaction of inhaled materials with the target tissue must be examined to understand the underlying mechanisms. In the first approach, pulmonary and systemic distribution of inhaled ultrafine elemental silver (EAg) particles was investigated on the basis of morphology and inductively coupled plasma mass spectrometry (ICP-MS) analysis. Rats were exposed for 6 hr at a concentration of 133 microg EAg m(3) (3 x 10(6) cm(3), 15 nm modal diameter) and were sacrificed on days 0, 1, 4, and 7. ICP-MS analysis showed that 1.7 microg Ag was found in the lungs immediately after the end of exposure. Amounts of Ag in the lungs decreased rapidly with time, and by day 7 only 4% of the initial burden remained. In the blood, significant amounts of Ag were detected on day 0 and thereafter decreased rapidly. In the liver, kidney, spleen, brain, and heart, low concentrations of Ag were observed. Nasal cavities, especially the posterior portion, and lung-associated lymph nodes showed relatively high concentrations of Ag. For comparison, rats received by intratracheal instillation either 150 microL aqueous solution of 7 microg silver nitrate (AgNO(3) (4.4 microg Ag) or 150 microL aqueous suspension of 50 microg agglomerated ultrafine EAg particles. A portion of the agglomerates remained undissolved in the alveolar macrophages and in the septum for at least 7 days. In contrast, rapid clearance of instilled water-soluble AgNO(3) from the lung was observed. These findings show that although instilled agglomerates of ultrafine EAg particles were retained in the lung, Ag was rapidly cleared from the lung after inhalation of ultrafine EAg particles, as well as after instillation of AgNO(3), and entered systemic pathways.
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PMID:Pulmonary and systemic distribution of inhaled ultrafine silver particles in rats. 1154 61

Silica-immobilized palladium catalysts are readily prepared by treating partially dehydroxylated silica with solutions of the palladium(II) complexes, cis-[PdMeXL2] (X = Me, L2 = dmpe; X = Cl, L2 = dmpe, dppe, phen, bipy, 2PMe3), trans-[PdMeXL2] (X = Cl, NO3, OTf, L = PMe3; X = Cl, L = PPh3), or [PdPh(OH)L]2 (L = PPh3, PCy3), at room temperature. A chemisorption reaction is presumed to occur on the surface Si-OH groups, with elimination of 1 equiv of methane, benzene, or water and the initial formation of a covalent Pd-O bond to the silica surface. The amount of chemisorbed material is strongly dependent on the nature of the complex employed, and the Pd content of the materials, determined by ICP analysis, was found to vary widely (from 1.47 to 0.021 wt %). It appears that the complexes stabilized by more basic ligands undergo a more facile reaction with the surface. The catalytic activity of the materials was first tested in the cyclization of 6-aminohex-1-yne. Higher conversions were found for those catalysts containing more basic ligands, due to the higher loadings, and for those complexes containing more weakly coordinating anions. Silica/trans-[PdMe(NO3)(PMe3)2] was identified as the best catalyst and was used to test the generality of the catalytic cyclization method with two other alkynes, namely, 5-phenyl-4-pentyn-1-amine and 6-phenyl-5-hexyn-1-amine. The catalysts prepared here show rates comparable to, or greater than, those found for homogeneous late transition metal complexes, including their molecular precursors. Furthermore, the supported catalysts are only slightly air-sensitive and can be recycled, after filtration in air, with only moderate loss of activity.
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PMID:Preparation of new catalysts by the immobilization of palladium(II) species onto silica: an investigation of their catalytic activity for the cyclization of aminoalkynes. 1167 83

Based on the negative charge of polycarboxylic chelators, an anion-exchange separation has been developed that is compatible with sensitive metal detection by ICP-MS. A low capacity hydrophilic polymer (AS11) was used as the anion exchanger and ammonium nitrate as the eluent. The new procedure provided high selectivity in the isocratic mode as well as a large separation window and high separation efficiency in the gradient mode. This was demonstrated for different types of chelators and their metal complexes. The aminopolycarboxylates NTA, EDTA, CDTA, DTPA, EDDS and for the EDTA derivatives HEDTA, ED3A and EDTMP, the phosphonic acid analogue of EDTA were tested. Their retention times generally depended on the charge, which was lower in 1:1 metal chelator complexes. Evaluation of the separation mechanism demonstrated that they were all separated predominantly by an anion-exchange mechanism with only a minor contribution from hydrophobic attraction. The method is useful for species identification and for predicting the charge of unknown analogous species from retention times. A gradient separation procedure achieved on-column preconcentration and matrix removal for the interference-free detection of metal chelates down to low nanomolar concentration in samples from various fields of environmental research.
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PMID:Determination of strong binding chelators and their metal complexes by anion-exchange chromatography and inductively coupled plasma mass spectrometry. 1188 54

Biogenic (e.g. phytochelatins, porphyrins, DOM) as well as anthropogenic (e.g. NTA, EDTA, phosphonates) chelators affect the mobility and cycling of heavy metals in environmental waters. Since such chelators can form strongly bound anionic heavy metal complexes that are stable and highly mobile, anion-exchange chromatography coupled to ICP-MS was investigated. A narrow bore HPLC system was connected to a micro concentric nebuliser for in-line sample introduction. A new chromatographic procedure based on a synthetic hydrophilic quaternary ammonium anion exchanger in combination with nitrate as a strong eluent anion, and gradient elution, provided high separation selectivity and a large analytical window. Low detection limits (nmol L(-1)) were achieved by on-column matrix removal and sample preconcentration. This allowed the method to be successfully applied to different environmental research areas. In ecotoxicological studies of heavy metal effects on algae low concentrations of metal EDTA complexes were determined in nutrient solutions without interference from high (buffer) salt concentrations. In groundwater, infiltrated by a polluted river, mobile metal EDTA species were observed. In river water of different pollution levels beside CuEDTA other anionic Cu-complexes were found in nmol L(-1) concentrations.
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PMID:Speciation of heavy metals in environmental water by ion chromatography coupled to ICP-MS. 1193 32

An extraction method was developed for the determination of toxic elements in contaminated soil samples by inductively coupled plasma atomic emission spectrometry (ICP-AES). The determination of arsenic, cadmium, lead, and silver in ultrasound-assisted extracts of SRM 2710 and SRM 2711 by ICP-AES was carried out with high accuracy and precision (RSD<3.7%). The certified concentrations of the SRMs were obtained for arsenic, cadmium, lead, and silver by using an ultrasound-assisted extraction method with a digestion solution of (1+1)-diluted aqua regia. The determination of copper in SRMs by the ultrasound-assisted extraction method and analysis by ICP-AES failed to obtain the certified concentrations at the 95% level of confidence using (+/-2 s) as confidence limits of the mean. However, the same results were observed with the use of the microwave digestion method and reflux, which is the ISO 11466 standard method. The analysis of the SRMs showed that the ultrasound-assisted extraction method is highly comparable with the other methods used for such purposes. The major advantages of the ultrasound-assisted extraction method compared to the microwave and reflux methods are the high treatment rate (50 samples simultaneously in nine minutes) and low reagent usage, the main benefit of which are the low chloride and nitrate concentrations in the extracts.
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PMID:Ultrasound-assisted extraction in the determination of arsenic, cadmium, copper, lead, and silver in contaminated soil samples by inductively coupled plasma atomic emission spectrometry. 1201 78

Ruthenium isotopic data for a pure Aldrich ruthenium nitrate solution obtained using a Nu Plasma multi collector inductively coupled plasma-mass spectrometer (MC-ICP-MS) shows excellent agreement (better than 1 epsilon unit = 1 part in 10(4)) with data obtained by other techniques for the mass range between 96 and 101 amu. External precisions are at the 0.5-1.7 epsilon level (2sigma). Higher sensitivity for MC ICP-MS compared to negative thermal ionization mass spectrometry (N-TIMS) is offset by the uncertainties introduced by relatively large mass discrimination and instabilities in the plasma source-ion extraction region that affect the long-term reproducibility. Large mass bias correction in ICP mass spectrometry demands particular attention to be paid to the choice of normalizing isotopes. Because of its position in the mass spectrum and the large mass bias correction, obtaining precise and accurate abundance data for 104Ru by MC-ICP-MS remains difficult. Internal and external mass bias correction schemes in this mass range may show similar shortcomings if the isotope of interest does not lie within the mass range covered by the masses used for normalization. Analyses of meteorite samples show that if isobaric interferences from Mo are sufficiently large (Ru/Mo < 10(4)), uncertainties on the Mo interference correction propagate through the mass bias correction and yield inaccurate results for Ru isotopic compositions. Second-order linear corrections may be used to correct for these inaccuracies, but such results are generally less precise than N-TIMS data.
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PMID:High-precision Ru isotopic measurements by multi-collector ICP-MS. 1214 10

Tin is considered to be a priority contaminant by the Codex Alimentarius Commission. Tin can enter foods either from natural sources, environmental pollution, packaging material or pesticides. Higher concentrations are found in processed food and canned foods. Dissolution of the tinplate depends on the of food matrix, acidity, presence of oxidising reagents (anthocyanin, nitrate, iron and copper) presence of air (oxygen) in the headspace, time and storage temperature. To reduce corrosion and dissolution of tin, nowadays cans are usually lacquered, which gives a marked reduction of tin migration into the food product. Due to the lack of modern validated published methods for food products, an ICP-AES (Inductively coupled plasma-atomic emission spectroscopy) method has been developed and evaluated. This technique is available in many laboratories in the food industry and is more sensitive than atomic absorption. Conditions of sample preparation and spectroscopic parameters for tin measurement by axial ICP-AES were investigated for their ruggedness. Two methods of preparation involving high-pressure ashing or microwave digestion in volumetric flasks were evaluated. They gave complete recovery of tin with similar accuracy and precision. Recoveries of tin from spiked products with two levels of tin were in the range 99+/-5%. Robust relative repeatabilities and intermediate reproducibilities were <5% for different food matrices containing >30 mg/kg of tin. Internal standard correction (indium or strontium) did not improve the method performance. Three emission lines for tin were tested (189.927, 283.998 and 235.485 nm) but only 189.927 nm was found to be robust enough with respect to interferences, especially at low tin concentrations. The LOQ (limit of quantification) was around 0.8 mg/kg at 189.927 nm. A survey of tin content in a range of canned foods is given.
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PMID:Determination of total tin in canned food using inductively coupled plasma atomic emission spectroscopy. 1232 43

The article reviews effects of nitrogen (N) deposition on beech forest ecosystems in Europe. On the basis of beech plots of the Pan-European Monitoring Programme of ICP Forests and the EU, the deposition of N compounds as well as input-output budgets are listed and compared with studies in North America. The authors also discuss the critical threshold for N leaching. At present, N is leached in 10% of the plots evaluated. An in-depth evaluation of a beech plot in central Germany is presented. The high N leaching results in a considerable increase (four times higher N content in 2000 compared to 1965) in the export of nitrate from the beech forests from a nearby source. Finally, ecophysiological indicators (N content in beech leaves, fine root system, N content, root/shoot ratios) are discussed as a result of high N input.
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PMID:Assessments of impacts of nitrogen deposition on beech forests: results from the Pan-European Monitoring Programme. 1280

In this paper, the decomposition method of sulfur and the determination of trace arsenic in sulfur by GFAAS with La(NO3)3-Ni(NO3)2 matrix modifier were studied in detail. The decomposition of sulfur with mixed acid HNO3-HClO4 by controlled temperature electrothermal method or pressure crucible method was efficient and safe. The sensitivity of the determination of arsenic with La(NO3)3-Ni(NO3)2 matrix modifier was higher than with Ni(NO3)2 or Mg(NO3)2 matrix modifiers. The detection limit was 0.034 microgram.mL-1 (k = 3). The analytical results of the sulfur samples were coincident with the results of determination by HG-ICP-AES. The adding recoveries were 97.5%-110% and the relative standard deviation was less than or equal to 2.1% (n = 4).
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PMID:[Determination of trace arsenic in sulfur by graphite furnace atomic absorption spectrometry with La(NO3)3-Ni(NO3)2 matrix modifier]. 1294 52


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