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Colloidal organo-mineral associations contribute to soil organic matter (OM) preservation and mainly occur in two forms: (i) as water-dispersible colloids that are potentially mobile (free colloids) and (ii) as building units of soil microaggregates that are occluded inside them (occluded colloids). However, the way in which these two colloidal forms differ in terms of textural characteristics and chemical composition, together with the nature of their associated OM, remains unknown. To fill these knowledge gaps, free and occluded fine colloids220 nm were isolated from arable soils with comparable organic carbon (C

Size resolved elemental characterisation of nanoparticles and colloids is routinely performed via flow field flow fractionation online with inductively coupled plasma mass spectrometry (ICP-MS) for a variety of sample matrices. However, low molecular weight elemental species (i.e. the dissolved fraction in the context of this study) pass with the cross flow through the membrane of the separation channel and thus escape detection. The lack of information on the dissolved fraction is a significant disadvantage compared to centrifugal field flow fractionation and chromatographic techniques. This fraction is relevant to determine the ratio of free and particle bound nutrients or toxicologically relevant elemental species, to establish the dissolution rate of non-stabilised (nano)particles and to establish a mass balance for quality control of the fractionation results. Fraction collection of the cross flow followed by off-line elemental analysis is rarely performed to determine the dissolved fraction because of delayed elution through the frit of the channel, dilution and elevated blank levels for some elements. Therefore, a novel approach was developed in this study enabling the online monitoring of the dissolved fraction in the cross flow. A special interface was constructed to convert the discontinuous cross flow into a continuous flow to the ICP-MS. Two frit materials, ceramic and steel, were investigated to overcome the challenges of the interaction of dissolved elemental species with the frit and to improve recovery. Quantification was performed both for aqueous standard solutions and for environmental water samples using ultrafiltration as a reference method. Finally, a combined method including monitoring of the dissolved fraction in the cross flow and the particulate fractions in the detector flow was established. Comparison of the dissolved fraction obtained with the new method and via ultrafiltration indicates the suitability of the developed approach for environmental water samples with mean recoveries in the range of 87% to 120% for Ca, Mg and Si. In the case of Al and P the dissolved fraction is in the low μg L−1 range resulting in partially elevated recoveries but their concentrations match within their confidence intervals.

Microaggregates (250 µm) that resisted 60 J mL−1 ultrasonic dispersion. Afterwards, we assessed the C, N, Fe, and Si stable isotope composition in each size fraction. After four weeks we found a rapid build-up of stable macroaggregates comprising almost 50 % of soil mass in the treatment with plants and respective soil rooting, but only 5 % when plants were absent. The formation of these stable macroaggregates proceeded with time. Soil organic carbon (SOC) contents were elevated by 15 % in the large macroaggregates induced by plant growth. However, the recovery of EPS-derived 13C was below 20 % after 4 weeks, indicating rapid turnover in treatments both with and without plants. The remaining EPS-derived C was mainly found in macroaggregates when plants were present and in the occluded small microaggregates (

Two once-through steam generators and a combination of a steam generator and a gas preheater for supplying feed gases to solid-oxide electrolysis stacks were evaluated for their carryover characteristics of contaminants from the feed-water into the steam phase. The concentrations of various trace impurities in the steam were determined by sampling the steam condensates and screening them with inductively coupled plasma–mass spectrometry for 19 elements and liquid ion chromatography and continuous flow analysis for chloride and ammonium. Steam-soluble species such as boric acid undergo complete volatilization and transfer into the steam phase. During unstable evaporation in the steam generators an extensive physical carryover of alloying metal species was observed. At realistic operation conditions for steam electrolysis, the gas preheater caused a considerable release of silicon into the steam phase. Two stack experiments were performed with common preheater temperatures and showed largely increased cell voltage degradation at higher operation temperatures. The post-test chemical analysis of cell samples revealed significant concentrations of silicon in the samples that are regarded as primary cause for increased degradation. These findings could partially explain the wide spread of degradation rates reported for solid-oxide steam electrolysis experiments.

This work presents results for the profiling of eight essential elements (Co, Cu, Ni, V, Mo, Mn, Zn and Cr) in aqueous and enzymatic extracts of eight anti-diabetic medicinal plants, used by Traditional Medicine Practitioners from Nyamira County, Kenya determined by ICP-MS. The plants used in the study were Solanum indicum, Plectranthus barbatus, Ultrica dioica, Bidens pilosa, Solanum mauense, Clerodendrum myricoides, Carissa edulis and Aloe vera. A sequential filtration procedure was applied to fractionate the elemental contents of the obtained aqueous extracts into molecular size fractions. The results indicate that the low molecular size species (3 kDa) were predominant for Mo, Zn, Ni, Co, Mn and Cu, while the moderately large species (10 kDa-0.45 μm) of V were predominant in most of the medicinal plant extracts. In addition enzymatic extraction was compared to aqueous extraction to study the effect of the gastric and intestinal conditions on the release of selected elements from the plants. The amount of the elements extracted by the gastric phase enzymes was higher than the amount extracted by the intestinal phase enzymes. In general, the determined elemental amounts of enzymatic extractions were higher than those of corresponding water extractions for 70% of the elements studied.

Nano and colloidal particles (1-1000 nm) play important roles in phosphorus (P) migration and loss from agricultural soils; however, little is known about their relative distribution in arable crop soils under varying agricultural geolandscapes at the regional scale. Surface soils (0-20 cm depth) were collected from 15 agricultural fields, including two sites with different carbon input strategies, in Zhejiang Province, China, and water-dispersible nanocolloids (0.6-25 nm), fine colloids (25-160 nm), and medium colloids (160-500 nm) were separated and analyzed using the asymmetrical flow field flow fractionation technique. Three levels of fine-colloidal P content (3583-6142, 859-2612, and 514-653 μg kg-1) were identified at the regional scale. The nanocolloidal fraction correlated with organic carbon (Corg) and calcium (Ca), and the fine colloidal fraction with Corg, silicon (Si), aluminum (Al), and iron (Fe). Significant linear relationships existed between colloidal P and Corg, Si, Al, Fe, and Ca and for nanocolloidal P with Ca. The organic carbon controlled colloidal P saturation, which in turn affected the P carrier ability of colloids. Field-scale organic carbon inputs did not change the overall morphological trends in size fractions of water-dispersible colloids. However, they significantly affected the peak concentration in each of the nano-, fine-, and medium-colloidal P fractions. Application of chemical fertilizer with carbon-based solid manure and/or modified biochar reduced the soil nano-, fine-, and medium-colloidal P content by 30-40%; however,the application of chemical fertilizer with biogas slurry boosted colloidal P formation. This study provides a deep and novel understanding of the forms and composition of colloidal P in agricultural soils and highlights their spatial regulation by soil characteristics and carbon inputs.

Regular algal blooms are occurring in Taihu lake, which may be triggered by resuspension of sediments containing relevant amounts of phosphorus. Therefore, our study aims at quantification of phosphorus concentrations bound to suspended particulate matter in Taihu water samples to investigate this hypothesis. A field flow fractionation (FFF) method online with ICP-MS detection was developed to achieve an overview on particulate fractions of phosphorus and related elements including Fe, Al and C from the low nanometer to the low micrometer size range. Mass balance of dissolved and particulate elemental contents was established for quality control purpose and indicated low recovery of Fe, Al and P. Complementary determination of volume based particle size distribution by dynamic imaging analysis showed a majority of particle volume and thus mass in particles with size >5 μm. In order to address this challenge, the upper particle size limit of FFF online with ICP-MS was for the first time investigated in detail using well characterised monodisperse latex particles as model for organic matter in the low micrometer size range including microalgae. The effect of pre-filtration of the sample as well as the contribution of sample introduction via three different interfaces including micromist nebuliser/spray chamber, direct injection nebulisation and APEX with heated spray chamber and solvent removal by condensation on the particulate carbon recovery was studied by ICP-MS detection. The same instrumental setup was also applied for the characterisation of particulate elemental contents in the Taihu water samples as far as possible. Significant improvement of the detected particulate fraction in Taihu water samples was achieved by increasing the membrane pore size for pre-filtration and by using the APEX for introduction of the eluate from FFF into ICP-MS.

Non-invasive imaging of β-cells represents a desirable preclinical and clinical tool to monitor the change of β-cell mass and the loss of function during pre-diabetic stages. Although it is widely accepted that manganese (Mn) ions are actively gated by voltage-dependent calcium channels (VDCC) in response to glucose metabolism, little is known on its specificity in vivo for quantification of islet β-cell function using Mn and magnetic resonance imaging (MRI). On the other hand, glucagon-like-peptide-1 receptor (GLP-1R) represents a validated target for the estimation of β-cell mass using radiolabeled exendin-4 (Ex4) and positron emission tomography (PET). However, a multiparametric imaging workflow revealing β-cell mass and function quantitatively is still missing. Methods: We developed a simultaneous PET/MRI protocol to comprehensively quantify in vivo changes in β-cell mass and function by targeting, respectively, GLP-1R and VDCC coupled with insulin secretion. Differences in the spatial distribution of Mn and radiolabeled Ex4 were monitored overtime in native and transgenic pancreata, characterized by spontaneous pancreatic neuroendocrine tumor development. Follow-up with mass spectrometry imaging (MSI) and autoradiography allowed the ex vivo validation of the specificity of Mn and PET tracer uptake and the detection of endogenous biometals, such as calcium and zinc, throughout the endocrine and exocrine pancreas. Results: Our in vivo data based on a volumetric PET/MRI readout for native pancreata and insulinomas connects uptake of Mn measured at early imaging time points to high non-specific binding by the exocrine tissue, while specific retention was only found 24 h post injection. These results are supported by cross-validation of the spatial distribution of exogenous 55Mn and endogenous 44Ca and 64Zn as well with the specific internalization of the radiolabeled peptide targeting GLP-1R. Conclusion: Simultaneous PET/MR imaging of the pancreas enabled the comprehensive in vivo quantification of β-cell function and mass using Mn and radiolabeled Ex4. Most important, our data revealed that only late time-point measurements reflect the Mn uptake in the islet β-cells, while early time points detect non-specific accumulation of Mn in the exocrine pancreas.

Biogeochemical changes of whole catchments may, at least in part, be deduced from changes in stream water composition. We hypothesized that there are seasonal variations of natural nanoparticles (NNP; 1–100 nm) and fine colloids (

Asymmetric flow field flow fractionation (AF4) in particular online with elemental detection via inductively coupled plasma mass spectrometry (ICP-MS) has been developed as powerful and flexible separation technique for suspensions of nano- and micro-particles covering a broad range of applications including environmental water samples and soil extracts. However, for challenging applications, such as particulate phosphorus determination in non-contaminated water samples at levels close to the limit of detection the throughput of the analytical field flow fractionation (FFF) is not sufficient. The same holds true for more specific identification and quantification of black carbon (BC) which needs a subsequent complex multi-step analysis using the well-established benzene polycarboxylic acids (BPCA) method. To overcome these limitations, the performance of a commercially available preparative AF4 channel, which has rarely been applied, yet, was investigated in this study. Using the example of an extract from charcoal spiked soil, method development for the preparative channel was performed and the results from six replicate fractionations with multi-element online detection by ICP-MS were compared to the results from the analytical channel for the same extracts. A similar fractionation pattern was achieved and the quantitative results agreed well for most of the particulate fractions (ratio 1.7 with standard deviation (SD) 0.2 for fraction 1, ratio 0.81 with SD 0.14 for fraction 2 and ratio 1.1 with SD 0.2 for fraction 3). Relative standard deviations were in the range of 9% to 18% for the preparative channel and between 3% and 17% for the analytical channel. Transferability of the separation parameters between both channels is discussed as well as the operational challenges of the preparative channel. As proof of principle, preparative fractionation of an extract from charcoal spiked soil was performed with fraction collection and subsequent quantification of BC via the BPCA method including derivatization, cation exchange pre-cleaning and finally gas chromatographic separation and quantification via flame ionization detection. The results indicated the majority of detected BC in the often so-called dissolved fraction was bound to nanoparticles (48%) and colloids (27%). Only 25% was detected in the cross flow (truly dissolved fraction). This successful example opens new possibilities for hyphenation of FFF separation with multiple detection techniques for improved characterization of particulate matter in challenging applications.

Nanoparticles and colloids affect the mobilisation and availability of phosphorus for plants and microorganisms in soils. We aimed to give a description of colloid sizes and composition from forest soil profiles and to evaluate the size-related quality of colloids for P fixation. We investigated the size-dependent elemental composition and the P content of water-dispersible colloids (WDC) isolated from five German (beech-dominated) forest soil profiles of varying bulk soil P content by field-flow fractionation (FFF) coupled to various detectors. Three size fractions of WDC were separated: (i) nanoparticles

Biogeochemical cycling of elements largely occurs in dissolved state, but many elements may also be bound to natural nanoparticles (NNP, 1-100 nm) and fine colloids (100-450 nm). We examined the hypothesis that the size and composition of stream water NNP and colloids vary systematically across Europe. To test this hypothesis, 96 stream water samples were simultaneously collected in 26 forested headwater catchments along two transects across Europe. Three size fractions (~1-20 nm, >20-60 nm, and >60 nm) of NNP and fine colloids were identified with Field Flow Fractionation coupled to inductively coupled plasma mass spectrometry and an organic carbon detector. The results showed that NNP and fine colloids constituted between 2 ± 5% (Si) and 53 ± 21% (Fe; mean ± SD) of total element concentrations, indicating a substantial contribution of particles to element transport in these European streams, especially for P and Fe. The particulate contents of Fe, Al, and organic C were correlated to their total element concentrations, but those of particulate Si, Mn, P, and Ca were not. The fine colloidal fractions >60 nm were dominated by clay minerals across all sites. The resulting element patterns of NNP

Supplemental digital content is available in the text., Objectives Retrospective studies in patients with primary brain tumors or other central nervous system pathologies as well as postmortem studies have suggested that gadolinium (Gd) deposition occurs in the dentate nucleus (DN) and globus pallidus (GP) after multiple administrations of primarily linear Gd-based contrast agents (GBCAs). However, this deposition has not been associated with any adverse effects or histopathological alterations. The aim of this preclinical study was to systematically examine differences between linear and macrocyclic GBCAs in their potential to induce changes in brain and skin histology including Gd distribution in high spatial resolution. Materials and Methods Fifty male Wistar-Han rats were randomly allocated into control (saline, n = 10 rats) and 4 GBCA groups (linear GBCAs: gadodiamide and gadopentetate dimeglumine, macrocyclic GBCAs: gadobutrol and gadoteridol; n = 10 rats per group). The animals received 20 daily intravenous injections at a dose of 2.5 mmol Gd/kg body weight. Eight weeks after the last GBCA administration, the animals were killed, and the brain and skin samples were histopathologically assessed (hematoxylin and eosin; cresyl violet [Nissl]) and by immunohistochemistry. The Gd concentration in the skin, bone, brain, and skeletal muscle samples were analyzed using inductively coupled plasma mass spectroscopy (ICP-MS, n = 4). The spatial Gd distribution in the brain and skin samples was analyzed in cryosections using laser ablation coupled with ICP-MS (LA-ICP-MS, n = 3). For the ultra-high resolution of Gd distribution, brain sections of rats injected with gadodiamide or saline (n = 1) were assessed by scanning electron microscopy coupled to energy dispersive x-ray spectroscopy and transmission electron microscopy, respectively. Results No histological changes were observed in the brain. In contrast, 4 of 10 animals in the gadodiamide group but none of the animals in other groups showed macroscopic and histological nephrogenic systemic fibrosis–like skin lesions. The Gd concentrations observed in the skin/brain samples (in nanomole Gd per gram of tissue) for each agent were as follows: gadodiamide: 1472 ± 115/11.1 ± 5.1, gadopentetate dimeglumine: 80.8 ± 6.2/13.1 ± 7.3, gadobutrol: 1.1 ± 0.5/0.7 ± 0.4, and gadoteridol: 1.7 ± 0.8/0.5 ± 0.2. The average detected residual Gd concentration in the brain was approximately 15-fold higher for linear than for macrocyclic GBCAs. The highest amounts of Gd found in brain corresponded to less than 0.0002% of the injected dose per gram of tissue. Using LA-ICP-MS, high Gd concentrations in the deep cerebellar nuclei and in the granular layer of the cerebellar cortex were detected only for linear gadodiamide and gadopentetate dimeglumine but not for gadoteridol or gadobutrol. The energy dispersive x-ray spectroscopy analysis revealed Gd-containing spots in the skin of animals administered gadodiamide and gadopentetate dimeglumine. Transmission electron microscopy revealed several Gd-containing spots in the region of the dentate nuclei in the brain of 1 animal injected with gadodiamide. Conclusions After repeated high dosing, nephrogenic systemic fibrosis–like macroscopic and histopathological lesions of the skin were observed only in some of the gadodiamide-treated animals. No histopathological findings were detected in the rodent brain. The administration of linear GBCAs was associated with significantly higher Gd concentrations in the brain and skin compared with macrocyclic GBCA administration. The results of LA-ICP-MS demonstrated local accumulation of Gd within the deep cerebellar nuclei and the granular layer only after the administration of linear agents. In summary, the detected low Gd concentrations in the skin and brain were well correlated with the higher kinetic stability of macrocyclic GBCA.

Platinum–DNA adducts, and in particular Pt–GG, have been identified as the major cytotoxic species during chemotherapy treatment with platinum containing drugs. This paper reports for the first time a strategy based on the use of double species-specific isotope dilution analysis (IDA) for the quantification of carboplatin–GG adducts formed by exposing human lung carcinoma cells to carboplatin. The main challenge posed by the use of carboplatin in this pre-clinical application, in comparison with most previously reported studies using cisplatin, includes the relatively low reactivity of this drug, thus demanding for improved limits of detection to be achieved in order to perform accurate quantification of the adducts at low ng Pt per mg DNA levels with relatively small uncertainty in micro-volumes of the biological sample. This was alleviated by developing micro-flow HPLC reversed phased methodology coupled to sector field ICP-MS (R = 300), showing a limit of detection of 0.2 ng Pt per mg DNA. To perform IDA, carboplatin–GG calibrants and spikes (194Pt-enriched GG adducts) were synthesized in house and characterised for Pt mass fraction, Pt distribution and structural composition. In order to assess the accuracy of the developed procedure, in the absence of certified reference materials, a reference sample prepared by incubation of calf thymus DNA with carboplatin and characterised in house (e.g. for its total P and Pt contents and Pt–GG concentration) was analysed in parallel. The use of this sample as a quality control of the cleavage of DNA and recovery of Pt adducts from real samples makes the described strategy particularly novel. Moreover, spike recovery experiments on the cell samples with the reference carboplatin–DNA sample were undertaken. The validated methodology was applied to cultured human lung carcinoma cells exposed to carboplatin; Pt–GG adducts were found to be at a level of 5.54 ng Pt per mg DNA with a relatively expanded combined uncertainty (k = 2) of approximately 20%. The major contributing factors to the overall measurement uncertainty were the mass fraction of Pt in the natural carboplatin–GG standard, the measured isotope ratio precision of sample and calibration blends and the blend to blend variation. The SI traceable methodology presented here will be invaluable for the provision of reference values to clinical measurements and cancer clinical trials.

A large number of medicinal plants is traditionally known in Kenya and used for treatment of various diseases, for example diabetes, where metals are supposed to be involved in pathogenesis and therapy. Therefore, detailed investigation of the concentration of a large number of metals in medicinal plants is required for improved understanding and optimisation of the therapeutic role of metals and also to exclude potentially toxic effects. Our study focused on the determination of 30 selected elements in 19 medicinal plant species each collected from 3 sampling locations in Nyamira County, Kenya. The obtained comprehensive data set showed large variability and multivariate data analysis revealed that the differences in the elemental composition were stronger dependent on the plant species than on the sampling location. In addition, hot water extractions were performed to mimic the traditional preparation of medicine from the plants. It was found that the mean extraction efficiencies were below 20% except for B, Mg, P, K, Mn, Co, Ni, Cu, Zn, Rb, Mo, Cd and Tl, which are mostly essential elements apart from Cd and Tl. Sequential (ultra)filtration of the extracts was applied as novel approach for molecular size-fractionation of the extracted elemental species. The results indicate more than 50% low molecular weight species (3 kDa up to

The high temperature air oxidation of the two conventionally cast Ni-based superalloys Rene 80 containing 92 wt ppm boron and CM 247 containing 110 wt ppm of boron was studied at temperatures between 850 and 1050 °C and times ranging from 1 to 100 h. Analysis by GD-OES and SEM/WDX/EBSD revealed the surface scale on Rene 80 after exposure at 1050 °C to consist of Cr2O3 with TiO2 in the outer part and BCrO3 and CrTi2O5 in the inner part. Internal Al2O3 precipitates were present below the external scale. After 1 h exposure of CM 247 an inner dense alumina scale formed over eutectic alloy regions containing coarse γ′ precipitates. Over dendritic regions a Cr-rich oxide scale with BCrO3-precipitates formed initially and aluminum was internally oxidized. After longer oxidation times an alumina sub-scale grew from the internal precipitates, and oxidation of the initially present depleted alloy zones resulted in formation of outer Ni and Co rich oxides. In both alloys, boron depletion in the bulk alloy occurred due to formation of the mentioned boron rich oxide. The extent of depletion was substantially higher for the chromia forming Rene 80 than for CM 247. In the latter material the boron depletion was suppressed after the formation of the dense, inner alumina scale.

Reliable and efficient analytical techniques are required for quantitative size-resolved carbon determination of nanoparticles and colloids in complex sample matrices due to the key role of carbon in biological and environmental processes. Field flow fractionation (FFF) online with inductively coupled plasma mass spectrometry (ICP-MS) is a powerful technique for identification and quantification of particle bound metals, but has not been applied for quantitative determination of particulate carbon, yet, due to several challenges. Therefore, our study explores the potential of online particulate carbon detection by ICP-MS to overcome limitations of previously used UV detection or offline total organic carbon measurements. A novel organic carbon detector (OCD) was used as independent sensitive carbon detector to validate the ICP-MS results. Basic validation of organic carbon detection by offline quadrupole and sector-field ICP-MS was performed for fresh water samples using OCD as reference achieving recoveries of 107 ± 16% with Q-ICP-MS and 122 ± 22% with SF-ICP-MS. Limits of detection were 0.6 mg L−1 for Q-ICP-MS, 0.3 mg L−1 for SF-ICP-MS and 0.04 mg L−1 for OCD. The main focus was on comparison of FFF-ICP-MS and FFF-OCD for quantification of particulate carbon in fresh water samples, soil extracts as well as in bovine serum albumin (BSA) as candidate reference standard. Recoveries obtained by FFF-Q-ICP-MS with a flow-injection calibration approach were in a range from 90 to 113% for replicate analyses of fresh water samples compared to FFF-OCD and from 87 to 107% with an alternative post-channel calibration strategy.

Purpose To investigate the long-term course of MRI signal intensity (SI) changes and the presence of gadolinium in the rat brain during a 1-year period after multiple administrations of gadolinium-based contrast agents (GBCAs). Materials and Methods Rats received a linear GBCA (gadodiamide, gadopentetate dimeglumine, gadobenate dimeglumine), a macrocyclic GBCA (gadobutrol, gadoterate meglumine, gadoteridol), or saline. Animals received eight injections over 2 weeks (1.8 mmol/kg per injection). Brain MRI and gadolinium measurements were performed with inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS 5, 26, and 52 weeks after administration. Results Animals that received linear GBCAs showed higher deep cerebellar nuclei (DCN)-to-brainstem SI ratios compared with the saline group (P.001 at all time points). After 1 year, mean gadolinium concentrations in the cerebellum were 3.38 nmol/g (gadodiamide), 2.13 nmol/g (gadopentetate dimeglumine), and 1.91 nmol/g (gadobenate dimeglumine). For linear agents, laser ablation ICP-MS revealed gadolinium depositions in the cerebellar nuclei. For macrocyclic GBCAs, the DCN-to-brainstem SI ratios did not significantly differ from those in the saline group (P.42) and the cerebellar gadolinium concentrations decreased between weeks 5 and 52, reaching 0.08 nmol/g (gadobutrol), 0.04 nmol/g (gadoterate meglumine), and 0.07 nmol/g (gadoteridol). The respective laser ablation ICP-MS analysis showed no gadolinium depositions. Conclusion Increased signal intensity in the deep cerebellar nuclei of rats persists for at least 1 year after administration of linear gadolinium-based contrast agents (GBCAs), in line with persistent brain gadolinium concentrations with no elimination after the initial 5-week period. The animals that received macrocyclic GBCAs showed an ongoing elimination of gadolinium from the brain during the entire observation period. © RSNA, 2018.

This tutorial review focuses on the use of ICP-MS based techniques for the analysis of metal-containing nanoparticles and colloids. Within the first part the capabilities of “stand alone” ICP-MS for the analysis of total metal contents and the suitability of stable isotopes for nanoparticle tracking (stable isotope labelling and naturally occurring variation in isotope ratios) are introduced (Chapter 3). Special focus was given on single particle ICP-MS (sp-ICP-MS) mode (Chapter 4). Upon a brief introduction into the theoretical concept, critical aspects such as calibration strategies, dwell time as well as ionic background were discussed and practical advice is given. References to current data assessment sheets are provided. Furthermore, a brief chapter on general sample preparation aspects is included within the first part (Chapter 2). The second part is dedicated to fractionation/separation systems, such as field-flow fractionation (FFF), hydrodynamic chromatography (HDC), high performance liquid chromatography (HPLC) and capillary electrophoresis (CE) coupled on-line with ICP-MS detection for metal-based nanoparticle and colloid analysis (Chapter 5). Each section starts with an introduction into the theoretical concept of the respective fractionation/separation system, followed by practical hints regarding method development (e.g. selection of appropriate carrier/mobile phase, membrane/stationary phase) as well as critical aspects and limitations. Particular attention is payed to laser ablation ICP-MS (LA-ICP-MS) for spatially resolved nanoparticle analysis. Each section concludes with selected application examples of the respective analytical technique from the most relevant fields of nanoparticle use or exposure (consumer products, food, medicine and environment), highlighting the performance of each technique in metal-based nanoparticle analysis. Chapter 6 is dedicated to aspects of quality assurance. Various critical points regarding method development and validation, mass balance, size calibration and quantification from the previous sections are revisited, discussed and practical advice is given. Finally, the authors provide some concluding remarks and future perspectives (Chapter 7). Furthermore, a flow-chart is included as a “hands-on” overview on all ICP-MS based techniques discussed within this tutorial review intended as a “method-decision tool” for users.

There is a broad range of carbon based engineered particles including polymer latex particles and carbon black. Also in environmental systems particulate carbon such as humic acids and soot or coal (the latter two summarized as black carbon) is of great importance and is involved in nutrient storage and (re)cycling. Therefore, detailed characterisation of the size distribution and elemental composition of such particles is required to understand the material properties and their environmental relevance. Field flow fractionation (FFF) online with inductively coupled plasma mass spectrometry (ICP-MS) is routinely applied for the characterisation of metal containing particles. However, the far majority of FFF studies relies on UV detection for organic carbon while elemental detection of carbon has hardly been used. Our previous work demonstrated the capability of FFF-ICP-MS for the determination of carbon in fine particulate matter, focusing on humic acid in water samples. The current work investigates the feasibility of carbon detection and quantification in larger particles with sizes up to about 750 nm. For this purpose, latex particle size standards of 21 nm, 100 nm, 250 nm and 740 nm were analysed as well as extracts of charcoal spiked soil. Elemental analysis using combustion techniques was employed as reference for the total carbon content of the samples to establish a mass balance. Recoveries for FFF separation of latex particle standards were in the range from 69% to 83% and in the range from 78% to 104% in flow injection mode. Carbon mass balance calculated from FFF fractionation, ultrafiltration and total content for the extracts from soil and charcoal spiked soil achieved 76% to 105%. Variation of the sampling depth was investigated to check if increased dwell time of the particles in the plasma affects the carbon ionisation and quantification. No significant change of carbon recoveries was observed, yet the signal to noise ratio improved 3-fold. This study provides a method for the analyses of carbon containing particles via FFF-ICP-MS, which allows for the first time the simultaneous measurement of carbon and other nutrients and is hence more timesaving than other methods.

Pseudomonas putida rubredoxin-2 (Rxn2) is an essential member of the alkane hydroxylation pathway and transfers electrons from a reductase to the membrane-bound hydroxylase. The regioselective hydroxylation of linear alkanes is a challenging chemical transformation of great interest for the chemical industry. Herein, we report the preparation and spectroscopic characterization of cobalt-substituted P. putida Rxn2 and a truncated version of the protein consisting of the C-terminal domain of the protein. Our spectroscopic data on the Co-substituted C-terminal domain supports a high-spin Co(II) with a distorted tetrahedral coordination environment. Investigation of the two-domain protein Rxn2 provides insights into the metal-binding properties of the N-terminal domain, the role of which is not well understood so far. Circular dichroism, electron paramagnetic resonance and X-ray absorption spectroscopies support an alternative Co-binding site within the N-terminal domain, which appears to not be relevant in nature. We have shown that chemical reconstitution in the presence of Co leads to incorporation of Co(II) into the active site of the C-terminal domain, but not the N-terminal domain of Rxn2 indicating distinct roles for the two rubredoxin domains.

The leaching of P from the upper 20 cm of forest topsoils influences nutrient (re-)cycling and the redistribution of available phosphate and organic P forms. However, the effective leaching of colloids and associated P forms from forest topsoils was so far sparsely investigated. We demonstrated through irrigation experiments with undisturbed mesocosm soil columns, that significant proportions of P leached from acidic forest topsoils were associated with natural colloids. These colloids had a maximum size of 400 nm. By means of Field-flow fractionation the leached soil colloids could be separated into three size fractions. The size and composition was comparable to colloids present in acidic forest streams known from literature. The composition of leached colloids of the three size classes was dominated by organic carbon. Furthermore, these colloids contained large concentrations of P which amounted between 12 and 91% of the totally leached P depending on the type of the forest soil. The fraction of other elements leached with colloids ranged between 1% and 25% (Fe: 1–25%; Corg: 3–17%; Al

The conventionally cast Ni-base superalloy Rene 80 containing 90 wt ppm boron was oxidized in synthetic air at 850–1,050 °C for times up to 100 h. Extensive microstructural studies using GD-OES and SEM/WDX/EBSD revealed formation of a porous chromia scale containing TiO2 precipitates at its outer surface and semi-continuous layers of BCrO3 and CrTi2O5 at its base. The development of B-rich oxide in the scale is related to its high thermodynamic stability and the high alloy boron diffusivity. Its enrichment in the oxide scale resulted in B-depletion from the alloy matrix, which was extremely rapid at 1,050 °C, draining the boron content of a 2 mm thick alloy coupon in 100 h. After 100 h exposure at 950 °C, the B-content dropped below 40 wt ppm, but only minor depletion was found after 100 h at 850 °C. Predictions of B-depletion based on calculation of its diffusion from a thin, flat sheet were in good agreement with experiment at 1,050 °C. Precipitation of B-containing compounds (borides) within the alloy is shown to account qualitatively for slower B-outdiffusion at lower temperatures.

This study is focusing on a novel approach to screen a large number of medicinal plants from Kenya regarding their contents and availability of selected metals potentially relevant for treatment of diabetes patients. For this purpose, total levels of zinc, chromium, manganese, and copper were determined by flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry as well as BCR sequential extraction to fractionate the elemental species in anti-diabetic medicinal plants collected from five natural locations in two sub counties in Nyamira County, Kenya. Solanum mauense had the highest zinc level of 123.0 ± 3.1 mg/kg while Warburgia ugandensis had the lowest level of 13.9 ± 0.4 mg/kg. The highest level of copper was in Bidens pilosa (29.0 ± 0.6 mg/kg) while the lowest was in Aloe vera (3.0 ± 0.1 mg/kg). Croton macrostachyus had the highest manganese level of 1630 ± 40 mg/kg while Clerodendrum myricoides had the lowest (80.2 ± 1.2 mg/kg). The highest level of chromium was in Solanum mauense (3.20 ± 0.06 mg/kg) while the lowest (0.04 ± 0.01 mg/kg) were in Clerodendrum myricoides and Warburgia ugandesis among the medicinal plants from Nyamira and Borabu, respectively. The levels of the elements were statistically different from that of other elements while the level of a given element was not statistically different in the medicinal plants from the different sub counties. Sequential extraction was performed to determine the solubility and thus estimate the bioavailability of the four investigated essential and potentially therapeutically relevant metals. The results showed that the easily bioavailable fraction (EBF) of chromium, manganese, zinc, and copper ranged from 6.7 to 13.8%, 4.1 to 10%, 2.4 to 10.2%, and 3.2 to 12.0% while the potentially bioavailable fraction (PBF) ranged from 50.1 to 67.6%, 32.2 to 48.7%, 23.0 to 41.1%, and 34.6 to 53.1%, respectively. Bidens pilosa, Croton macrostachyus, Ultrica dioica, and Solanum mauense medicinal plants used to treat diabetes by 80 % of the herbalists in Nyamira County were found to be rich in chromium, manganese, copper, and zinc. The EBF of zinc, manganese, and chromium constitutes adequate amounts recommended for daily intake not exceeding the ADI and delivered a low percentage of RDA when estimating daily intake during therapy from typically applied doses. The plants did not show any significant differences at p

This work represents a first systematic approach to the size-based elemental quantification and size estimation of metal(loid) oxide nanoparticles such as silica (SiO2) in a real food matrix using asymmetric flow field-flow fractionation coupled online with inductively coupled plasma mass spectrometry (ICP-MS) and multi-angle light scattering (MALS) and offline with transmission electron microscopy (TEM) with energy-dispersive X-ray analysis (EDAX). Coffee creamer was selected as the model sample since it is known to contain silica as well as metal oxides such as titania at the milligramme per kilogramme levels. Optimisation of sample preparation conditions such as matrix-to-solvent ratio, defatting with organic solvents and sonication time that may affect nanoparticle size and size distribution in suspensions was investigated. Special attention was paid to the selection of conditions that minimise particle transformation during sample preparation and analysis. The coffee creamer matrix components were found to stabilise food grade SiO2 particles in comparison with water suspensions whilst no significant effect of defatting using hexane was found. The use of sample preparation procedures that mimic food cooking in real life was also investigated regarding their effect on particle size and particle size distribution of silica nanoparticles in the investigated food matrix; no significant effect of the water temperature ranging from ambient temperature to 60 °C was observed. Field-flow fractionation coupled to inductively coupled plasma-mass spectrometry (FFF-ICP-MS) analysis of extracts of both unspiked coffee creamer and coffee creamer spiked with food grade silicon dioxide, using different approaches for size estimation, enabled determination of SiO2 size-based speciation. Element-specific detection by ICP-MS and post-FFF calibration with elemental calibration standards was used to determine the elemental composition of size fractions separated online by FFF. Quantitative data on mass balance is provided for the size-based speciation of the investigated inorganic nano-objects in the complex matrix. The combination of FFF with offline fractionation by filtration and with detection by ICP-MS and TEM/EDAX has been proven essential to provide reliable information of nanoparticle size in the complex food matrix.

Stagnant water conditions may release phosphorus (P) in soil solution that was formerly bound to Fe oxides. To understand which P species are potentially involved, we obtained water extracts from the surface soils of a gradient from Cambisol, Stagnic Cambisol to Stagnosol from temperate grassland, Germany. These were filtered to Stagnosol. Across all soil types, elevated proportions of inositol hexakisphosphate species (e.g. myo-, scyllo-, and D-chiro-IHP) were associated with soil mineral particles (i.e. bulk soil and small-sized soil colloids) whereas other orthophosphate monoesters and phosphonates were found in the ‘dissolved’ P fraction. We conclude that stagnic properties affect P speciation and availability by potentially releasing dissolved inorganic and ester-bound P forms as well as nano-sized organic matter-Fe/Al-P colloids.

International audience; This chapter reviews the current knowledge of important functions of selenium (Se) and selenoproteins in physiology and pathology in human. The outcome of the different clinical trials reveals the need for a better understanding of Se biology. The physiology of Se depends on its continuous supply to the body and its optimal distribution to tissues. The development and application of mass spectrometry imaging (MSI) techniques are of great interest in cancer research and diagnosis to study elemental distributions in biological tissue samples at microscopic level. The ability to record spatial accumulation of multiple analytes in tissue samples under native conditions and to directly correlate obtained images with histological features has made MSI an invaluable analytical tool. The chapter concentrates on literature about manganese (Mn) speciation targeting neurodegeneration effects, first, in human samples, such as serum or cerebrospinal fluid (CSF) samples, where some studies were summarized in 2007. It also presents a case study of Alzheimer's disease.

Due to the limited solubility of phosphorus (P) in soil, understanding its binding in fine colloids is vital to better forecast P dynamics and losses in agricultural systems. We hypothesized that water-dispersible P is present as nanoparticles and that iron (Fe) plays a crucial role for P binding to these nanoparticles. To test this, we isolated water-dispersible fine colloids (WDFC) from an arable topsoil (Haplic Luvisol, Germany) and assessed colloidal P forms after asymmetric flow field-flow fractionation coupled with ultraviolet and an inductively coupled plasma mass spectrometer, with and without removal of amorphous and crystalline Fe oxides using oxalate and dithionite, respectively. We found that fine colloidal P was present in two dominant sizes: (i) in associations of organic matter and amorphous Fe (Al) oxides in nanoparticles

The increased use of nanoparticles in industrial and medical products is driving the need for accurate, high throughput in vitro testing procedures to screen new particles for potential toxicity. While approaches using standard viability assays have been widely used, there have been increased reports of the interactions of nanoparticles with their soluble labels or optical readouts which raise concerns over the potential generation of false positive results. Here, we describe the use of an impedance spectroscopy approach to provide real-time reagent free detection of toxicity for a panel of metal oxide nanoparticles (ZnO, CuO, and TiO(2)). Using this approach, we show how impedance measurements can be used to track nanoparticle toxicity over time with comparable IC(50) values to those of standard assays (ZnO-55 μg/mL, CuO-28 μg/mL) as well as being used to identify a critical 6 h period following exposure during which the nanoparticles trigger rapid cellular responses. Through targeted analysis during this response period and the use of a novel image analysis approach, we show how the ZnO and CuO nanoparticles trigger the active export of intracellular glutathione via an increase in the activity of the ATP dependent MRP/1 efflux pumps. The loss of glutathione leads to increased production of reactive oxygen species which after 2.5 h triggers the cells to enter apoptosis resulting in a dose dependent cytotoxic response. This targeted testing strategy provides comprehensive information beyond that achieved with standard toxicity assays and indicates the potential for cell-nanoparticle interactions that could occur following in vivo exposure.

Citrate complexes of Mn and Fe, and potentially those of Cu and Zn, are considered as important low molecular mass species in human serum and cerebrospinal fluid (CSF). For example, Mn is supposed to enter the brain under excess exposure as Mn-citrate leading to neurotoxic effects. Mn-citrate has been characterised in human CSF using chromatography and electrophoresis online with inductively coupled plasma mass spectrometry, but not yet with molecular mass spectrometry. Therefore, this study explores the potential of electrospray ionisation (ESI) with selected reaction monitoring (SRM) for the detection of metal-citrate complexes, in particular Mn-citrate. The collision-induced dissociation of precursor ions with various metal:citrate stoichiometries was studied for Mn-citrate, Fe-citrate, Cu-citrate and Zn-citrate. High selectivity was achieved for Mn(II)-citrate even in respect to Fe(III)-citrate which forms isobaric precursor ions. The limit of detection for Mn-citrate was estimated to be around 250 µg L−1 (referring to the total Mn content in the standard) using flow injection. The sensitivity was sufficient for the determination of Mn-citrate in standard solutions and in an extract of an Mn-citrate-containing supplement. An improved ESI source design is expected to reduce the limits of detection significantly. The developed ESI-SRM method has the potential to provide complementary data for the quality control of current separation methods for metal citrates using element-selective detection, with application to biomedical samples and further matrices. Copyright © 2009 John Wiley & Sons, Ltd.

Neurodegenerative diseases like Alzheimer's disease and Parkinson's disease are gaining increasing relevance in our aging society. However, the complex multifactorial mechanisms of these diseases are not sufficiently understood yet. Several studies indicate that metal ions play an important role in the promotion of these diseases. Consequently, the transport pathways of metals and their species to the brain are of special interest. Following oral or inhalative uptake metals are absorbed and distributed via the blood stream in the body. Transport into the brain requires crossing of the neural barriers. Our study focuses on the investigation of the permeability of the blood-cerebrospinal fluid (CSF)-barrier for selected metals (Mn, Fe, Cu, Zn, Mg and Ca). For the first time paired human serum and CSF samples obtained from a neurological department were characterised for total metal concentrations and metal species. For CSF few data are available in the literature on total metal contents and applications of element speciation analysis in CSF samples are rare. In our study mean CSF/serum ratios (n=29) were 0.7 for Mn, 0.02 for Fe, 0.02 for Cu, 0.03 for Zn, 1.3 for Mg and 0.5 for Ca. Size exclusion chromatography (SEC) online with inductively coupled plasma mass spectrometry was further developed for the size characterisation of the metal species in CSF and serum with limits of detection of 0.4microgL(-1) for Fe, 0.01microgL(-1) for Mn, 0.2microgL(-1) for Cu, 0.2microgL(-1) for Zn, 0.6microgL(-1) for Mg and 3.8microgL(-1) for Ca in the eluate from the HPLC column. Apart from Mn the application of this technique has not been published for metal speciation in CSF, yet. In the case of some Mn species it turned out that methanol, which was contained in the mobile phase of a SEC method previously published from our group on qualitative characterisation of Mn species, was interfering with the quantification. The modified method developed in this work (with NaCl but without methanol in the mobile phase; use of internal standard) allowed reliable quantification. The results clearly indicate changes in the metal species pattern due to different permeation behaviour at the blood-CSF-barrier. As part of the method validation the relative stability of complexes of albumin, transferrin and citrate with Mn, Fe, Cu and Zn was investigated.

The narrow gap between essentiality and toxicity of selenium requires detailed investigations on selenium metabolism in order to find suitable indicators for the selenium status in the human body. Current methods for quantitative selenium speciation in human urine are based on separation by high-performance liquid chromatography (HPLC) coupled online with elemental mass spectrometry (MS), and the potential of molecular MS detection techniques for the reliable identification and quantification of selenosugars in crude human urine has not been utilized. Now we report the development of an HPLC tandem mass spectrometric (MS/MS) method for the reliable determination in crude human urine of three significant selenium urinary metabolites, collectively termed selenosugars, namely methyl 2-acetamido-2-deoxy-1-seleno-beta-D-galactopyranoside (SeGalNAc), methyl 2-acetamido-2-deoxy-1-seleno-beta-D-glucopyranoside (SeGluNAc) and methyl 2-amino-2-deoxy-1-seleno-beta-D-galactopyranoside (SeGalNH2). Reversed-phase HPLC, with and without cation-exchange guard columns, was applied for the separation of the selenosugars, and atmospheric pressure chemical ionization (APCI) and selected reaction monitoring (SRM) were used for selective and sensitive detection. The collision-induced dissociation behaviour of the selenosugars was studied in detail using APCI triple quadrupole MS/MS and electrospray ion trap MS. The developed method was applied to urine samples collected prior to and after selenium supplementation for the quantification of SeGalNAc using both external calibration and the method of standard additions. Additionally, SeGalNH2 was detected in urine samples after Se supplementation. Finally, neutral loss scanning was explored as a possible method for the detection of unknown methyl-selenosugars.

Their increasing commercial availability and their rather high total arsenic contents necessitate a more detailed arsenic speciation analysis of marine algal products. Compared to current HPLC-ICPMS methods, HPLC on-line with electrospray tandem mass spectrometry in the selected reaction monitoring mode (HPLC-ES-SRM) offers much higher detection selectivity with similarly high sensitivity for most known organoarsenic species. This study demonstrates the advantages of HPLC-ES-SRM for the detection of the main as well as trace arsenic species in extracts of 12 commercially available marine algal powders. The main focus was the unambiguous identification of the detected arsenic species. Four quality control tools were applied for this purpose, including matching chromatographic retention times, comparing SRM transition ratios, recording product ion spectra, and determining accurate masses. As a result, evidence was obtained for the presence of 19 organoarsenic species in the analyzed algal extracts. The method of standard addition was used for quantification. Estimated matrix effects on the analyte signal were similar for most of the investigated arsenic species in extracts of different types of brown algae. This allowed the comparison of the contents of the arsenic species present in the 12 algal extracts on the basis of normalized peak areas. A partial correlation of the arsenic speciation pattern with the algal family or algal order, respectively, was found.

Following recent reports on the detection of the new group of thioarsenosugars in marine molluscs we have developed two chromatographic methods in order to explore the presence of additional species of this group in biological samples. A series of thioarsenosugar standards, containing four different thioarsenosugars in total, was prepared and used for method optimization. First, conventional anion exchange chromatographic conditions were modified to achieve efficient elution of the thioarsenosugars. This required relatively high contents of methanol in the mobile phase (up to 40%). Online hyphenation with electrospray tandem mass spectrometry provided good quality product ion mass spectra for the thioarsenosugars. These allowed the generation of collision induced dissociation breakdown curves for each compound which finally resulted in the development of a very sensitive and specific selected reaction monitoring approach. However, the high amount of methanol used with this method was not optimum for direct hyphenation with inductively coupled plasma mass spectrometry (ICP-MS) without a specially adapted interface. Therefore, reversed phase anion pairing HPLC with a low methanol content (5%) in the mobile phase was developed and used in this case. The combined application of both analytical techniques revealed the presence of two novel thioarsenosugars in marine bivalves and marine algae. Moreover, this is the first time that the detection of thioarsenosugars in marine algae is reported.

Recently, the identification of four thio-arsenosugars in extracts of marine samples was reported. The biosynthesis of these arsenic species is most likely closely related to the well known oxo-arsenosugars. Due to their symbiotic algae giant clams contain oxo-arsenosugars with Carboxyl-, Carbamate- and Adenine-aglycone in significant amounts. Now we provide evidence for the presence of the thio analogues of these three arsenosugars in tissue extracts of the giant clams Tridacna maxima and Tridacna derasa. Anion-exchange high-performance liquid chromatography (HPLC) online with electrospray tandem mass spectrometry was applied for the identification of the thio-arsenosugars and the indirect quantification via their oxo analogues.

The large number of arsenic species known to be present in marine samples and their broad range of chemical properties pose a significant challenge for arsenic speciation analysis. The predominantly used ICPMS detection online with HPLC only provides element-selective information, which is not sufficient for the identification of arsenic species without standards. However, electrospray tandem mass spectrometry in the selected reaction monitoring (SRM) mode enables molecule-selective detection with high sensitivity for quantification. A new HPLC-ES-SRM method was developed for the determination of more than 20 organoarsenic species. Two chromatographic systems were compared, an anion exchange method and a combined cation anion exchange method. Collision-induced dissociation breakdown curves were constructed for all arsenic species investigated and used to optimize the SRM conditions. External calibration was performed with mixed standard solutions containing 21 arsenic species. Two SRM transitions were monitored for most of the analytes, and their intensity ratio was used for quality control. The developed methods were applied for the quantification of arsenic species in extracts of four marine reference materials. Spiking experiments revealed, especially for the early-eluting analytes on the anion exchange system, significant signal suppression by coeluting matrix constituents. Therefore, the standard addition approach was used for quantification. AsB, the major arsenic species in tuna CRM 627 and DORM-2, was accurately quantified with the combined cation anion exchange ES-SRM method.

For the optimisation of the extraction procedures PtCl42− and PtCl62− were used as model species for extractable Pt(II)- and Pt(IV)-compounds in road dust. A previously developed ion exchange chromatography–ICP–MS method was applied for the quantification of the Pt species in the extracts. A concept in three steps was realised. First, the stability of the model species in several extractants like HCl, methionine, EDTA and thiourea was studied under variation of the concentrations of the extracting agents, the pH and the supply of energy (refluxing, exposure to microwaves, sonication). Second, spiked road dust samples were extracted with those solvents that provided good results in the first step. The results from samples spiked with a mixture of both model species were compared to analogous extractions from dust samples which were spiked with only one of the chloroplatinates. Moreover, the extractant-to-dust-ratio was optimised. Third, the optimised procedures from the second step were applied to unspiked dust samples originating from two different road tunnels in order to characterise the extractable Pt species. The results of the optimisation proved that the model species are fairly stable in the extractants in the absence of the dust matrix. However, the recoveries of PtCl42− from the spiked dust samples were significantly lower and PtCl62− could not be recovered without transformation at all. The extraction efficiencies for total Pt from the unspiked samples were below 5%. The concentrations of the model species in the extracts of these samples were below the limit of detection of the applied HPLC–ICP–MS method. For quality control mass balances of total Pt were established for all extractions.

The emission of platinum from automobile catalytic exhaust converters is well known and the accumulation of Pt in road dust has been studied by the analysis of total Pt contents. However, there are few studies on the speciation of the emitted Pt-compounds in the environment. A separation method with HPLC-UV has been developed by Nachtigall et al. [Chromatogr. A 775 (1997) 197] with aqueous standards of Pt(II)- and Pt(IV)-chloro complexes. Due to the limited selectivity and sensitivity of the UV-detection this method is not suitable for Pt-speciation in road dust extracts. Therefore, in this study the method of Nachtigall et al. was modified to realize an on-line coupling to ICP-MS with the advantage of Pt-specific detection. Calibration was performed with aqueous standards and spiked road dust extracts. Calibration curves were linear with low residual standard deviation (1.3-3.1% for the aqueous standards) and approximately 10-times lower detection limits compared to the HPLC-UV-method. Moreover, the stability of the model species was investigated using isocratic as well as gradient separation. Isotopic ratios of 194Pt, 195Pt, 196Pt and 198Pt were determined for quality control. A new mathematical correction method for the HfO-interference on the 195Pt-signal was developed. Additionally, the elution pattern of further elements in the road dust extracts was monitored and total element contents were determined in unspiked road dust extracts.

The characterisation of trace element species in solid biomatrices like liver is necessary to obtain a more detailed knowledge of the complex functions and interactions of these compounds in organisms. Gentle i.e. species-preserving extraction techniques and chromatographic separation with multielement detection are useful methods for this purpose. In the present study extracts from porcine liver were investigated. Especially, Fe-, Cu-, Zn- and Mn-species were considered. Size exclusion chromatography and reversed phase chromatography were applied coupled either online to ICP-MS for species quantification via their trace element content or offline to ESI-MS for species identification via their molecular weight. Transferrin, metallothionein and superoxide dismutase were characterized. Additionally, total element contents in extracts and residues were determined with ICP-AES. Different sample pretreatment procedures were evaluated and the results from three previously optimised extraction procedures were compared in respect of extraction efficiency and species stability. Moreover, a cell fractionation of a liver homogenate was performed to investigate the subcellular location of selected trace element species. The results showed that freezing for several weeks does not significantly affect the stability of the quantified species. The Tris buffer provided the best extraction results. Cu- and Zn- species were detected mainly in the cytosolic fraction, Fe predominantly in the microsomal fraction. Mn is present in the cytosolic fraction as well as the mitochondrial/lysosomal fraction.

A two-dimensional chromatographic method for the characterization of metallothionein isoforms (MT) and superoxide dismutase (SOD) in spiked liver extracts was developed for the optimization of extraction procedures from liver samples. Element-specific detection (ICP-MS) and molecule-specific detection (ESI-MS) were applied for maximum species information. A special focus was laid on the quantitative data evaluation (species stoichiometry, calibration with and without matrix, recovery), which is neglected in most MT/SOD publications with hyphenated techniques. Linearity, precision (residual standard deviation of calibration curves

Two approaches have been used to investigate changes in the nature of metal binding in river sediments caused by atmospheric oxygen. Firstly, non-inert and inert sample preparation were applied, in combination with sequential extraction, to determine for which metals inert sample preparation is necessary for correct determination of metal mobility under environmental conditions. Secondly, the metal contents of sediments sampled before and after a river weir were fractionated by sequential extraction to study the effect of the oxygen impact at the weir on heavy metal mobility in the sediments. Different grain-size fractions from one sample were also extracted, to enable selection of the upper grain-size limit most suitable for answering this analytical question. The results showed the need for the inert sample preparation technique for Cd, Zn, Pb, Mn, and Fe, but not for Co, Ni, Cu, and Cr. No significant change of heavy metal mobility at the weir could be proved, although the mobilization behavior of some elements was different. The optimum upper grain-size limit was 63 microm.