Advancements in Portable Voltammetry: A Promising Approach for Iron Speciation Analysis

Iron, a crucial element in our environment, plays a vital role in numerous natural processes. Understanding the presence and concentration of iron in the environment is very important as it impacts various aspects of our planet's health. The on-site detection and speciation of iron are significant for several reasons. In this context, the present work aims to evaluate the applicability of voltammetry for the on-site determination of iron and its possible speciation using a portable voltammetric analyzer. Voltammetry offers the advantage of convenience and cost-effectiveness. For iron (III) determination, the modification of a glassy carbon electrode (GCE) with an antimony-bismuth film (SbBiFE) using the acetate buffer (pH = 4) as a supporting electrolyte was used. The technique adopted was Square Wave Adsoptive Cathodic Stripping Voltammetry (SW-AdCSV), and we used 1-(2-piridylazo)-2-naphthol (PAN) as the iron (III) ligand. Linearity, repeatability, detection limit, and accuracy were determined using synthetic solutions; then, a Standard Reference Material (SRM) of 1643f Trace Elements in Water (iron content: 93.44 ± 0.78 µg L-1) was used for validation measurements in the real matrix. the accuracy of this technique was found to be excellent since we obtained a recovery of 103.16%. The procedure was finally applied to real samples (tap, lake, and seawater), and the results obtained were compared via Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The amount of iron found was 207.8 ± 6.6 µg L-1 for tap water using voltammetry and 200.9 ± 1.5 µg L-1 with ICP-OES. For lake water, 171.7 ± 3.8 µg L-1, 169.8 ± 4.1 µg L-1, and 187.5 ± 5.7 µg L-1 were found using voltammetry in the lab both on-site and using ICP-OES, respectively. The results obtained demonstrate the excellent applicability of the proposed on-site voltammetric procedure for the determination of iron and its speciation in water.

Analytical Methods for the Characterization of Vegetable Oils

The determination of the authenticity of extra virgin olive oils (EVOOs) has become more interesting in recent years. Italy is the first country in Europe in terms of number of Protected Designation of Origin (PDO) oils, which connects consumers to a feeling of tradition and thus to higher quality standards. This work focused on the consideration of the inorganic content as a possible marker of EVOOs. Ten vegetable oils (VOs), eight Italian EVOOs and seven not Italian EVOOs were analyzed. After pretreatment by acid mineralization, Al, Ba, Ca, Cu, Fe, K, Li, Mg, Mn, Na, P, Sb, Se and Zn were determined by ICP-OES. The electrochemical properties of a selected group of EVOOs and other vegetal oils of different botanical origin were investigated by voltammetry. Carbon paste electrodes (CPEs) were prepared. The features observed in the voltammograms reflect the reactions of electroactive compounds, which are present in the oils. A chemometric treatment of the results was performed to assess the possibility to distinguish (i) the region of provenience considering the inorganic profile; and (ii) the plant species from which each oil was obtained on the basis of the current profile registered during voltammetric analysis. Inorganic composition seems to be a useful marker for the assessment of the geographical origin of an EVOO. The EVOO-CPEs voltammetry seems to have a good ability to distinguish the plant species of origin. This method could be useful to monitor the conservation status of the oils, as the redox profile is linked to the oxidative degradation state.

Strategies for mercury speciation with single and multi-element approaches by HPLC-ICP-MS

Mercury (Hg) and its compounds are highly toxic for humans and ecosystems, and their chemical forms determine both their behavior and transportation as well as their potential toxicity for human beings. Determining the various species of an element is therefore more crucial than understanding its overall concentration in samples. For this reason, several studies focus on the development of new analytical techniques for the identification, characterization, and quantification of Hg compounds. Commercially available, hyphenated technology, such as HPLC-ICP-MS, supports the rapid growth of speciation analysis. This review aims to summarize and critically examine different approaches for the quantification of mercury species in different samples using HPLC-ICP-MS. The steps preceding the quantification of the analyte, namely sampling and pretreatment, will also be addressed. The scenarios evaluated comprehend single and multi-element speciation analysis to create a complete guide about mercury content quantification.

Charge transfer modulation in charge transfer co-crystals driven by crystal structure morphology

The electronic properties of a charge-transfer (donor-acceptor) semiconducting organic co-crystal, Perylene:F4-TCNQ (PE:F4) (the donor, D, is PE and the acceptor, A, is 2,3,5,6-tetrafluoro-7,7,8,8 tetracyanoquinodimethane (F4)) in its 3 : 2 stoichiometry, are experimentally and theoretically studied. This is performed by means of electron paramagnetic resonance (EPR) and solid state electrochemical techniques, such as cyclic voltammetry (CV) measurements on single crystals. In particular, solid state electrochemistry proves to be an effective tool to probe, on a macroscopic scale, the electronic characteristics of the co-crystal. However, EPR highlights the presence of spin ½ radicals localized on F4 molecules, possibly linked to defects. The experimental findings are discussed on the basis of density functional theory (DFT) based calculations, carried out using both the projector augmented wave (PAW), with "periodic boundary conditions" (pbc), method and the localized orbitals, molecular cluster, approach. In particular, a satisfying agreement is found between the experimental, 0.336 eV (electrochemical), and theoretical, 0.303 eV (PAW), band gaps. Differences with the reported optical bandgap are discussed considering excitonic effects.

On-Site Determination of Methylmercury by Coupling Solid-Phase Extraction and Voltammetry

A measurement and speciation procedure for the determination of total mercury (Hg_TOT), inorganic mercury (Hg_IN), and methylmercury (CH₃Hg) was developed and the applicability for on-site determination was demonstrated. A simple, portable sample pretreatment procedure was optimized to extract the analytes. Home-made columns, packed with a new sorbent material called CYXAD (CYPHOS 101 modified Amberlite XAD), were used to separate the two forms of the analyte. Hg_TOT and CH₃Hg were determined by anodic stripping voltammetry (ASV), using a solid gold electrode (SGE). Two certified reference materials (BCR-463 Tuna Fish and Tuna Fish ERM-CE 464) and eight fresh fishes were analyzed. Then, the results that were obtained following the optimized portable procedure were compared with the concentrations obtained, using a direct mercury analyzer (DMA). This quantification, using the two techniques, demonstrated the good performance of the proposed method.

Mechanistic Insights into the Role of Iron, Copper, and Carbonaceous Component on the Oxidative Potential of Ultrafine Particulate Matter

Transition metals play a key role in the pathogenic potential of urban particulate matter (PM). However, air quality regulations include exposure limits only for metals having a known toxic potential like Pb, As, Cd, and Ni, neglecting other transition metals like Fe and Cu. Fe and Cu are mainly found in the water-soluble fraction of PM. However, a fraction of the ions may persist strongly bound to the particles, thus potentially acting as surface reactive sites. The contribution of surface ions to the oxidative potential (OP) of PM is likely different from that of free ions since the redox activity of metals is modulated by their local chemical environment. The aim of this study was to investigate how Fe and Cu bound to carbonaceous particles affect the OP and associated toxicity of PM toward epithelial cells and macrophages. Carbonaceous nanoparticles (CNPs) having well-defined size were loaded with controlled amounts of Cu and Fe. The effect of Cu and Fe on the OP of CNPs was evaluated by electronic paramagnetic resonance (EPR) spectroscopy associated with the spin-trapping technique and correlated with the ability to induce cytotoxicity (LDH, WST-1), oxidative stress (Nrf2 translocation), and DNA damage (comet assay) on lung macrophages (NR8383) and/or epithelial cells (RLE-6TN). The release of pro-inflammatory cytokines (TNF-α, MCP-1, and CXCL2) by macrophages and epithelial cells was also investigated. The results indicate a major contribution of surface Cu to the surface reactivity of CNPs, while Fe has a minor role. At the same time, Cu increases the cytotoxicity of CNPs and their ability to induce oxidative stress and DNA damage. In contrast, surface Fe increases the release of pro-inflammatory cytokines by macrophages. Overall, these results confirm the role of Cu and Fe in PM toxicity and suggest that the total metals content in PM might be a better indicator of pathogenicity than water-soluble metals.

Influence of start-up phase of an incinerator on inorganic composition and lead isotope ratios of the atmospheric PM10

A municipal solid waste incinerator (MSWI) was installed in a peripheral area of the city of Turin. In this study, we evaluated the contribution of this plant to the massive concentration of PM₁₀, to its chemical composition and to the distribution of the lead isotopes during the start-up phase.We assessed the inorganic composition of PM₁₀ collected in the vicinity of the Turin incinerator by inductively coupled plasma atomic emission spectroscopy (ICP-AES), magnetic sector inductively coupled plasma mass spectrometer (SF-ICP-MS) and ion chromatography (IC). The lead isotope ratios in PM₁₀ samples were determined by SF-ICP-MS by a method developed and optimized using experimental design approach. Element trends and data chemometric treatment evidence that the vehicular traffic, increased in this area due to the opening of the MSWI plant, and, to a lesser degree, the direct incinerator emissions influence As, Cd, Cr, Cu, Ba, Mo, Pb, Sn and Zn concentrations. As a whole, however, the element concentrations in PM₁₀ and the Enrichment Factors (EFs) were comparable with the values reported for other urban sites and target pollutant concentrations of MSWI emissions, namely Cd, Cr, Cu and Pb, were lower than in PM₁₀ emitted from older MSWIs. This confirms that incinerators of new installation have a lower impact on atmospheric PM₁₀ composition thanks to stricter current legislation and up-to-date technologies. The lead isotope ratios investigation allowed to distinguish the diverse sources (crustal, vehicular traffic and MSWI) that influence lead concentration in PM₁₀ collected near incinerator during start-up phase.

Machine Learning Profiling of Alzheimer's Disease Patients Based on Current Cerebrospinal Fluid Markers and Iron Content in Biofluids

Alzheimer's disease (AD) is the most common form of dementia, characterized by a complex etiology that makes therapeutic strategies still not effective. A true understanding of key pathological mechanisms and new biomarkers are needed, to identify alternative disease-modifying therapies counteracting the disease progression. Iron is an essential element for brain metabolism and its imbalance is implicated in neurodegeneration, due to its potential neurotoxic effect. However, the role of iron in different stages of dementia is not clearly established. This study aimed to investigate the potential impact of iron both in cerebrospinal fluid (CSF) and in serum to improve early diagnosis and the related therapeutic possibility. In addition to standard clinical method to detect iron in serum, a precise quantification of total iron in CSF was performed using graphite-furnace atomic absorption spectrometry in patients affected by AD, mild cognitive impairment, frontotemporal dementia, and non-demented neurological controls. The application of machine learning techniques, such as clustering analysis and multiclassification algorithms, showed a new potential stratification of patients exploiting iron-related data. The results support the involvement of iron dysregulation and its potential interaction with biomarkers (Tau protein and Amyloid-beta) in the pathophysiology and progression of dementia.

A mathematical model for the evaluation of iron transport across the blood-cerebrospinal fluid barrier in neurodegenerative diseases

Iron plays important roles in healthy brain but altered homeostasis and concentration have been correlated to aging and neurodegenerative diseases. Iron enters the central nervous system by crossing the brain barrier systems: the Blood- Brain Barrier separating blood and brain and the Blood-Cerebrospinal Fluid Barrier (BCSFB) between blood and CSF, which is in contact with the brain by far less selective barriers. Herein, we develop a two-compartmental model for the BCSFB, based on first-order ordinary differential equations, performing numerical simulations and sensitivity analysis. Furthermore, as input parameters of the model, experimental data from patients affected by Alzheimer's disease, frontotemporal dementia, mild cognitive impairment and matched neurological controls were used, with the aim of investigating the differences between physiological and pathological conditions in the regulation of iron passage between blood and CSF which can be possibly targeted by therapy.

Development of an easy portable procedure for on-site determination of mercury and methylmercury

A portable measurement and speciation procedure for inorganic mercury (Hg_IN) and methylmercury (CH₃Hg) was developed. A portable sample pretreatment was optimized to determine total mercury content. A new home-made sorbent (CYXAD, CHYPOS 101 modified Amberlite XAD), was prepared to separate Hg_IN and CH₃Hg. Mercury species were determined using square wave anodic stripping voltammetry (SW-ASV) with a solid gold electrode (SGE) and using a portable potentiostat. A certified reference material, five freeze-dried samples and three fresh samples were analysed with conventional voltammetric analyzer, after dissolution of the samples in microwave oven, and with a portable potentiostat after the mild eating procedure. The results obtained by SW-ASV were compared with those obtained using Direct Mercury Analyser (DMA). The quantification with the portable method is comparable to that obtained with the DMA. Retention tests showed the selectivity of CYXAD for Hg_IN, its stability and the possibility to re-use the same aliquot of resin.

The Inorganic Component as a Possible Marker for Quality and for Authentication of the Hazelnut's Origin

The inorganic component of hazelnuts was considered as a possible marker for geographical allocation and for the assessment of technological impact on their quality. The analyzed samples were Italian hazelnuts of the cultivar Tonda Gentile Romana and Turkish hazelnuts of the cultivars Tombul, Palaz and Çakildak. The hazelnuts were subjected to different drying procedures and different conservative methods. The concentration of 13 elements, namely Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, Sn, Sr and Zn, were quantified by inductively coupled plasma optical emission spectroscopy (ICP-OES). All the samples were previously digested in a microwave oven. Before proceeding with the analysis of the samples, the whole procedure was optimized and tested on a certified reference material. The results show that the inorganic component: (i) can represent a fingerprint, able to identify the geographical origin of hazelnuts, becoming an important quality marker for consumer protection; (ii) is strongly influenced by the treatments undergone by the investigated product during all the processing stages. A pilot study was also carried out on hazelnuts of the cultivar Tonda Gentile Trilobata Piemontese, directly harvested from the plant during early development to maturity and analyzed to monitor the element concentration over time.

Incorporation of Cró thermal water in a dermocosmetic formulation: cytotoxicity effects, characterization and stability studies and efficacy evaluation

OBJECTIVE

Development of cosmetic formulations to provide a controlled release of hydrophilic active compounds from mineral medicinal waters constitutes an attractive challenge. The objective of this study was the development and the characterization of a dermocosmetic gel formulation with Cró thermal water, from Beira Interior of Portugal, as a major functional ingredient.

METHODS

Concentrations of mineral chemical elements of Cró thermal water were previously determined by inductively coupled plasma-optical emission spectrometry or mass spectrometry and cytotoxicity assays using thermal water were carried out on normal human dermal fibroblasts (NHDF) cells. Then, the Cró thermal water was included (more than 90%) in a developed gel formulation that was characterized through rheological and texture analysis and submitted to stability assays during 30 days. The effects on the skin volunteers, namely skin pH, the degree of hydration, transepidermal water loss and skin relief, were evaluated through non-invasive biometric techniques. A gel formulation including purified water was used as a control.

RESULTS

Cró thermal water is rich on several chemical elements in particular sodium, silica, potassium and calcium besides some trace elements, with important functions for the skin. NHDF cells adhered and proliferated in the presence of thermal water confirming the biocompatibility of the major component of the gel formulation. The developed gel formulation based on thermal water resulted in an improvement of textural parameters, comparing with the purified water-based one. Significant improvements in the cutaneous biometric parameters (degree of hydration, transepidermal water loss and skin relief) of volunteers were also registered for the gel formulation containing thermal water.

CONCLUSION

This study demonstrated for the first time the potential benefits of Cró thermal water in a gel formulation to be used in cosmetic and dermatological applications.

Magnetic Iron Oxide Nanoparticles: Synthesis, Characterization and Functionalization for Biomedical Applications in the Central Nervous System

Magnetic Nanoparticles (MNPs) are of great interest in biomedicine, due to their wide range of applications. During recent years, one of the most challenging goals is the development of new strategies to finely tune the unique properties of MNPs, in order to improve their effectiveness in the biomedical field. This review provides an up-to-date overview of the methods of synthesis and functionalization of MNPs focusing on Iron Oxide Nanoparticles (IONPs). Firstly, synthesis strategies for fabricating IONPs of different composition, sizes, shapes, and structures are outlined. We describe the close link between physicochemical properties and magnetic characterization, essential to developing innovative and powerful magnetic-driven nanocarriers. In conclusion, we provide a complete background of IONPs functionalization, safety, and applications for the treatment of Central Nervous System disorders.

Dynamics of inorganic components in lake waters from Terra Nova Bay, Antarctica

Water and Suspended Particulate Material (SPM) samples analysed in this work were collected in the austral summer 2011/12 from six shallow Antarctic lakes (Carezza, Edmonson Point 14 and 15a, Gondwana, Inexpressible Island 10b and Tarn Flat 20) of Terra Nova Bay (Northern Victoria Land, Antarctica). The total concentrations of a large suite of inorganic analytes were determined, in order to gain insight into the natural processes regulating species distribution, define natural background values and detect possible present or future local and/or global anthropogenic contamination. Lake water composition was found to be influenced by marine spray, lake geographical position and meltwater input. Seasonal variability was also evaluated for each analyte, and explained considering the natural transport processes involving each species. Multivariate chemometric techniques were used in order to identify groups of samples with similar characteristics and find out similarities and correlations among variables. The variability observed within the water samples is closely connected to the marine aerosol input; hence, it is primarily a consequence of geographical and meteorological factors, such as distance from the ocean and period of year. Higher element concentrations have been found in SPM than in water, suggesting that weathering plays an important role on the chemistry of these lakes or that adsorption processes take place. SPM samples were also examined with a Scanning Electron Microscope (SEM), and many diatoms belonging to different species were detected. No clear evidence of a relevant metal contamination was found in the investigated area.

Element variability in lacustrine systems of Terra Nova Bay (Antarctica) and concentration evolution in surface waters

Major, minor and trace elements were determined in freshwater of lacustrine systems in Terra Nova Bay, along Victoria Land coast, Antarctica, as well as in algae and mosses. The samples were collected during some of the sampling campaigns between 2007 and 2011 (and the one of 2002) within the framework of the Italian National Program of Research in Antarctica (PNRA). Data were processed with chemometric techniques. Results showed that elements typically considered as potential anthropogenic pollutants (e.g. As, Pb, Zn, Cu and Ni) present a strong correlation with the lithogenic elements (e.g. Al, Si, Fe) in all matrices, suggesting that their origin is connected to natural phenomena. Metal concentrations in vegetation samples are in the same range as previously published data. The obtained results were compared with older literature data (since the early '90s) from the same lacustrine systems, in order to present a historical overview of element concentrations. This approach furnishes important information on surface water evolution as a function of time. A considerable variability was observed in metal concentrations but no clear trend was identified. This suggests that their concentration evolution is hardly correlated to specific natural or anthropic phenomena. No evidence of an increase of concentrations over time was apparent. Our results represent new important data about metal concentrations in lacustrine systems in Antarctica, furnishing ranges of values that can be considered as a reference. These data, therefore, could be used to detect or monitor future local and/or global anthropogenic contaminations.

Size resolved metal distribution in the PM matter of the city of Turin (Italy)

A work on the characterization of the air quality in the city of Turin was carried out in different sampling periods, reflecting early autumn and winter conditions, including a snow episode during the early 2012 European cold wave. The concentrations of 13 elements in eight size fractions of the aerosol were determined using inductively coupled plasma-mass spectrometry. The collection was carried out with a Andersen MkII cascade impactor. The size distribution of elements allowed the identification of three main behavioural types: (a) elements associated with coarse particles (Cd, Cr, Cu, Fe, Mn, Mo and Sn); (b) elements found within fine particles (As, Co, Pb and V) and (c) elements spread throughout the entire size range (Ni and Zn). Principal Component Analysis allowed to examine the relationships between the inorganic elements and to infer about their origin. Chemometric investigation and assessment of similarity in the distribution led to similar conclusions on the sources. The concentration of gaseous trace pollutants (O3, NOx and VOCs) was determined. The concentrations of these pollutants are scarcely correlated with the metal contents of all the size classes of the PM. The differences found in the O3, NO2 and VOCs levels of the two winter campaigns due to the high photochemical reactivity in the period after the snow episode, do not reflect in differences in the metals distribution in the PM. Since PM metals, NOx and VOC have common sources, this behaviour is due to relevant differences in the transformation and deposition processes.

Spatial distribution and potential sources of trace elements in PM10 monitored in urban and rural sites of Piedmont Region

The results on elemental composition of aerosol (PM10) sampled during 2011 in Piedmont region (Italy) are interpreted using meteorological data, Enrichment Factors (EF), chemometric processing by Principal Component Analysis (PCA), Factor Analysis (FA) and Hierarchical Cluster Analysis (HCA). Daily concentrations of about 30 elements were measured using HR-ICP-MS in five monitoring sites. A clear seasonal pattern, with higher concentrations in autumn and winter, was observed, particularly in the urban sites. Levels of As, Cd, Ni and Pb in most of the samples were within the limits imposed by the European legislation. Spatial differences in PM10 and metal concentrations were significant, with rural and urban sites showing different metal patterns, indicating different sources. K and Ca were used, respectively, as marker of biomass burning and industrial marker (cement plant); EFs showed that Ca was enriched just in one area and K was enriched only in the winter period considered and in some stations. Data analysis through PCA, FA and HCA allowed us to identify correlations among the investigated elements and similarities between sampling sites in order to individuate specific emission sources, such as non-exhaust vehicle emission.

Determination of major, minor and trace elements in Glyceric Macerates and Mother Tinctures and in the starting plant materials

Glyceric Macerates (GMs) and Mother Tinctures (MTs) are liquid preparations obtained from plant buds (for GMs) and flowers, leaves or roots (for MT) by extraction with a mixture of solvents. Their quality depends on the quality of the plant materials and on the preparation procedures. In this work we determined the concentrations of major, minor and trace elements in buds, flowers and other plant components and in the GMs and MTs obtained from them by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) after microwave mineralization. To the best of our knowledge, this procedure has been applied for the first time here to the analysis of buds. We have taken into account spectral interferences and other causes of errors. Analogies and differences with regard to the method reported by European Pharmacopoeia for heavy metal determination in herbal drugs have been highlighted. The experimental results have been interpreted with chemometric techniques. No significant contamination was detected during the manufacturing step. Element concentrations in GMs and MTs, taking into account their daily dosages, are lower than acceptable intake levels.

Room temperature ionic liquids as useful overlayers for estimating food quality from their odor analysis by quartz crystal microbalance measurements

An array of quartz crystals coated with different room-temperature ionic liquids (RTILs) is proposed for the analysis of flavors by quartz crystal microbalance (QCM) measurements. Seven RTILs were adopted as sensing layers, all containing imidazolium or phosphonium cations, differing from one another in the length and branching of alkyl groups and neutralized by different anions. The array was at first applied to the analysis of 31 volatile organic compounds (VOCs), such as alcohols, phenols, aldehydes, esters, ketones, acids, amines, hydrocarbons and terpenes, chosen as representative components of a wide variety of food flavors. Multivariate data analysis by the principal component analysis (PCA) approach of the set of the corresponding responses led to separated clusters for these different chemical categories. To further prove the good performance of the RTIL-coated quartz crystal array as an "electronic nose", it was applied to the analysis of headspaces from cinnamon samples belonging to different botanical varieties ( Cinnamon zeylanicum and Cinnamon cassia ). PCA applied to responses recorded on different stocks of samples of both varieties showed that they could be fully discriminated.

Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

Recently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30ppm cadmium(II) or 50ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plant's hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development.

Temporal trends of elements in Turin (Italy) atmospheric particulate matter from 1976 to 2001

The temporal trends of major, minor and trace elements in the total atmospheric particulate sampled in the urban area of Turin (Italy) were determined for the following years: 1976, 1986, 1996 and 2001. The wavelength dispersive X-ray fluorescence (WD-XRF) technique was adopted to determine the concentrations of Ba, Br, Ca, Cl, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, S, Ti and Zn. A smaller number of samples was also analysed by ICP atomic emission spectroscopy (ICP-AES) and the results were compared with those obtained by WD-XRF to confirm their validity. A clear seasonal pattern with higher concentrations of the aforementioned elements in the cold periods was observed. Moreover, a change in the chemical composition of atmospheric particulate matter was evidenced, particularly between the first (1976 and 1986) and the last (1996 and 2001) years. This change can be attributed both to the greater contribution of Pb and Br to atmospheric pollution in the past and, in recent years, to the higher level of pollutants associated with increased vehicular traffic and industrial activities. The application of chemometric techniques (Principal Component Analysis and Cluster Analysis) allowed us to speculate about the main emitting sources influencing the total atmospheric particulate in these years.

Fractionation and speciation of arsenic in three tea gardens soil profiles and distribution of As in different parts of tea plant (Camellia sinensis L.)

The distribution pattern and fractionation of arsenic (As) in three soil profiles from tea (Camellia sinensis L.) gardens located in Karbi-Anglong (KA), Cachar (CA) and Karimganj (KG) districts in the state of Assam, India, were investigated depth-wise (0-10, 10-30, 30-60 and 60-100 cm). DTPA-extractable As was primarily restricted to surface horizons. Arsenic speciation study showed the presence of higher As(V) concentrations in the upper horizon and its gradual decrease with the increase in soil depths, following a decrease of Eh. As fractionation by sequential extraction in all the soil profiles showed that arsenic concentrations in the three most labile fractions (i.e., water-soluble, exchangeable and carbonate-bound fractions) were generally low. Most arsenic in soils was nominally associated with the organic and Fe-Mn oxide fractions, being extractable in oxidizing or reducing conditions. DTPA-extractable As (assumed to represent plant-available As) was found to be strongly correlated to the labile pool of As (i.e. the sum of the first three fractions). The statistical comparison of means (two-sample t-test) showed the presence of significant differences between the concentrations of As(III) and As(V) for different soil locations, depths and fractions. The risk assessment code (RAC) was found to be below the pollution level for all soils. The measurement of arsenic uptake by different parts of tea plants corroborated the hypothesis that roots act as a buffer and hold back contamination from the aerial parts.

The role of chemometrics in single and sequential extraction assays: a review. Part II. Cluster analysis, multiple linear regression, mixture resolution, experimental design and other techniques

Single and sequential extraction procedures are used for studying element mobility and availability in solid matrices, like soils, sediments, sludge, and airborne particulate matter. In the first part of this review we reported an overview on these procedures and described the applications of chemometric uni- and bivariate techniques and of multivariate pattern recognition techniques based on variable reduction to the experimental results obtained. The second part of the review deals with the use of chemometrics not only for the visualization and interpretation of data, but also for the investigation of the effects of experimental conditions on the response, the optimization of their values and the calculation of element fractionation. We will describe the principles of the multivariate chemometric techniques considered, the aims for which they were applied and the key findings obtained. The following topics will be critically addressed: pattern recognition by cluster analysis (CA), linear discriminant analysis (LDA) and other less common techniques; modelling by multiple linear regression (MLR); investigation of spatial distribution of variables by geostatistics; calculation of fractionation patterns by a mixture resolution method (Chemometric Identification of Substrates and Element Distributions, CISED); optimization and characterization of extraction procedures by experimental design; other multivariate techniques less commonly applied.

Accumulation of heavy metals from contaminated soil to plants and evaluation of soil remediation by vermiculite

We evaluated the distribution of 15 metal ions, namely Al, Cd, Cu, Cr, Fe, La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr, in the soil of a contaminated site in Piedmont (Italy). This area was found to be heavily contaminated with Cu, Cr and Ni. The availability of these metal ions was studied using Tessier's sequential extraction procedure: the fraction of mobile species, which potentially is the most harmful for the environment, was much higher than that normally present in unpolluted soils. This soil was hence used to evaluate the effectiveness of treatment with vermiculite to reduce the availability of the pollutants to two plants, Lactuca sativa and Spinacia oleracea, by pot experiments. The results indicated that the addition of vermiculite significantly reduces the uptake of metal pollutants by plants, confirming the possibility of using this clay in amendment treatments of metal-contaminated soils. The effect of plant growth on metal fractionation in soils was investigated. Finally, the sum of the metal percentages extracted into the first two fractions of Tessier's protocol was found to be suitable in predicting the phytoavailability of most of the pollutants present in the investigated soil.

Determination of As(III) by anodic stripping voltammetry using a lateral gold electrode: experimental conditions, electron transfer and monitoring of electrode surface

The aim of this work is to evaluate the efficiency of the determination of As(III) by anodic stripping voltammetry (ASV) using a lateral gold electrode and to study the modifications of the electrode surface during use. Potential waveforms (differential pulse and square wave), potential scan parameters, deposition time, deposition potential and surface cleaning procedure were examined for they effect on arsenic peak intensity and shape. The best responses were obtained with differential pulse potential wave form and diluted 0.25 M HCl as supporting electrolyte. The repeatability, linearity, accuracy and detection limit of the procedure and the interferences of cations and anions in solution were evaluated. The applicability of the procedure for As(III) determination in drinking waters was tested. Cyclic voltammetry (CV) was used to study the electrochemical behaviour of As(III) and for the daily monitoring of electrode surface. Also scanning electron microscopy (SEM) analysis was used to control the electron surface. Finally we evaluated the possibility to apply the equations valid for flow systems also to a stirred system, in order to calculate the number of electrons transferred per molecule during the stripping step.

An approach for arsenic in a contaminated soil: speciation, fractionation, extraction and effluent decontamination

The fractionation and speciation of As in a contaminated soil were investigated, and a remediation strategy was tested. Regarding speciation, we found that As(V) prevails over As(III) whereas more than 40% of total arsenic is in organic form. The fractionation of As was investigated with two sequential extraction methods: a low mobility was found. Then we tested the possibility of using phosphoric acid to extract As from the soil and cleaning the washing effluents by sorption onto montmorillonite. The efficiency of the extraction and of the adsorption onto the clay were also investigated for Cr, Cu, Fe, Mn, Ni, Pb and Zn, whose total concentrations and fractionation in the soil are reported here. The extraction percentages for As and metals ranged from 30 to 65%; the residual proportions in the soil are presumably in very unreactive forms. Montmorillonite showed a good uptake capacity towards the investigated pollutants.

Adsorption of heavy metals on vermiculite: Influence of pH and organic ligands

The sorption behaviour of vermiculite has been studied with respect to cadmium, copper, lead, manganese, nickel, and zinc as a function of pH and in the presence of different ligands. The continuous column method was used in order to evaluate the feasibility to use the clay in wastewater purification systems. The total capacity of vermiculite was found to decrease in the following order: Mn > Ni > Zn > Cd > Cu > Pb. The adsorption of metal ions on vermiculite decreases with decreasing pH and increasing ionic strength. In general, the metal uptake on the clay was hindered by the presence of strong complexing agents in solution and it decreases with increasing of the complexation constants of the ligands with exception of cysteine and tiron. It is necessary, hence, to consider all these factors to effectively predict the uptake efficiency of this sorbent. However, it is possible to conclude that the vermiculite has good potentialities for cost-effective treatments of metal-contaminated wastewaters.

The Use of Sequential Extraction Procedures for the Characterization and Management of Contaminated Soils

Metal mobility and availability in solid samples, such as soils, sediments and sludges, is frequently studied with sequential extraction procedures, which allow to partition the total metal content into classes of different reactivity. From the experimental point of view, each extraction step requires many practical operations, which can represent sources of error if they are not properly executed. The first part of the paper gives indication on how to perform sequential extractions, from sample pretreatment to extract analysis, in order to reduce experimental errors. The second part describes the main applications of sequential extraction schemes for the characterization and management of contaminated soils: the assessment of the risks associated to metal pollution, the evaluation of the feasibility and efficiency of remediation techniques, the study of soil properties and of metal behaviour and plant availability.

Adsorption of heavy metals on Na-montmorillonite. Effect of pH and organic substances

Clays (especially montmorillonite and bentonite) are widely used as barriers in landfills to prevent contamination of subsoil and groundwater by leachates containing heavy metals. For this reason it is important to study the adsorption of metals by these clays. The sorption of seven metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) on Na-montmorillonite was studied as a function of pH and in the presence of ligands, forming complexes of different stabilities with the metals of interest. The continuous column method was used as it better simulates natural conditions. The total capacity of Na-montmorillonite towards these metals was determined. The pH variations influence to a higher extent the concentrations of Cu, Pb and Cd in the effluent. Moreover the results suggest that complex formation hinders the sorption of the metals on the clay, with an increasing influence in the order: Mn < or = Pb < or = Cd < or = Zn < Ni < Cu < Cr. The evaluation of the total capacity of Na-montmorillonite shows that this clay is a good sorbent towards all examined metals.

The use of mosses as environmental metal pollution indicators

The possibility of using mosses as environmental indicators of metal pollution has been investigated. Mosses of the species Bryum argenteum were collected from different parts of Piedmont (Italy), ranging from highly polluted areas to nearly uncontaminated mountain areas. Periodical samplings were planned in every site on a monthly base, in order to check variations of metal uptake throughout one year; correlations with pluviometric and thermal patterns were investigated for all sampling stations. On every moss sample 20 elements, ranging from major (K, P, Al, Ca, Fe and Mg) to minor (Mn, Na, Ti and Zn) and trace (As, Ba, Cd, Co, Cr, Cu, Li, Ni, Pb and Sr), were quantitatively determined by inductively coupled plasma-atomic emission spectrometry or graphite furnace-atomic absorption spectrometry, depending on the needed sensitivity. Statistical analyses, carried out with principal component analysis and cluster analysis methods, revealed that a good correlation exists between metal content in mosses and pollution degree in the areas sampled.

Heavy metals in agricultural soils from Piedmont, Italy. Distribution, speciation and chemometric data treatment

The distribution and speciation of heavy metals in five agricultural soils of Piedmont Region (north-western Italy) were investigated. Ten metals, namely Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Ti and Zn were considered. Analytical determinations were performed by atomic emission or atomic absorption spectroscopy after microwave sample dissolution in acid solution. Total metal concentrations fit in the typical concentration ranges for unpolluted soils, with the exception of cadmium and lead content in some horizons. The effect of sampling depth on concentrations was discussed. Speciation studies were carried out by applying Tessier's procedure, which allows to subdivide the total metal content into five fractions, representing portions bound to different components of the soil. Moreover, the element labilities in two soils were evaluated by extraction with EDTA. Correlations among the variables and/or similarities among the sampling points were identified by principal component analysis and hierarchical cluster analysis.

Determination of metals in wine with atomic spectroscopy (flame-AAS, GF-AAS and ICP-AES); a review

Metals in wine occur at the mg l(-1) level or less and, though not directly related to the taste of the final product, their content should be determined because excess is undesirable, and in some cases prohibited, due to potential toxicity. Lead content in wine, for example, is restricted in several states by legislation to guarantee consumer health protection. Of several methods for metal determination, techniques of atomic spectroscopy are the most sensitive and rapid. Most of the elements present in wine can be determined with these techniques, at concentrations ranging from the mg l(-1) to the microg l(-1) level. Here, inductively coupled plasma-atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry (flame-AAS) and graphite furnace-atomic absorption spectrometry (GF-AAS) are compared for their characteristics as employed in metal determination in wine.

Distribution and mobility of metals in contaminated sites. chemometric investigation of pollutant profiles

The distribution and mobility of heavy metals in the soils of two contaminated sites in Piedmont (Italy) was investigated, evaluating the horizontal and vertical profiles of 15 metals, namely Al, Cd, Cu, Cr, Fe. La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr. The concentrations in the most polluted areas of the sites were higher than the acceptable limits reported in Italian and Dutch legislations for soil reclamation. Chemometric elaboration of the results by pattern recognition techniques allowed us to identify groups of samples with similar characteristics and to find correlations among the variables. The pollutant mobility was studied by extraction with water, dilute acetic acid and EDTA and by applying Tessier's procedure. The fraction of mobile species, which potentially is the most harmful for the environment, was found to be higher than the one normally present in unpolluted soils, where heavy metals are, to a higher extent, strongly bound to the matrix.