Platinum group elements in the environment and their health risk

Effect of Nanoparticle Size and Natural Organic Matter Composition on the Bioavailability of Polyvinylpyrrolidone-Coated Platinum Nanoparticles to a Model Freshwater Invertebrate

The bioavailability of dissolved Pt(IV) and polyvinylpyrrolidone-coated platinum nanoparticles (PtNPs) of five different nominal hydrodynamic diameters (20, 30, 50, 75, and 95 nm) was characterized in laboratory experiments using the model freshwater snail Lymnaea stagnalis. Dissolved Pt(IV) and all nanoparticle sizes were bioavailable to L. stagnalis. Platinum bioavailability, inferred from conditional uptake rate constants, was greater for nanoparticulate than dissolved forms and increased with increasing nanoparticle hydrodynamic diameter. The effect of natural organic matter (NOM) composition on PtNP bioavailability was evaluated using six NOM samples at two nanoparticle sizes (20 and 95 nm). NOM suppressed the bioavailability of 95 nm PtNPs in all cases, and DOM reduced sulfur content exhibited a positive correlation with 95 nm PtNP bioavailability. The bioavailability of 20 nm PtNPs was only suppressed by NOM with a low reduced sulfur content. The physiological elimination of Pt accumulated after dissolved Pt(IV) exposure was slow and constant. In contrast, the elimination of Pt accumulated after PtNP exposures exhibited a triphasic pattern likely involving in vivo PtNP dissolution. This work highlights the importance of PtNP size and interfacial interactions with NOM on Pt bioavailability and suggests that in vivo PtNP transformations could yield unexpectedly higher adverse effects to organisms than dissolved exposure alone.

Emerging contaminants (Rh, Pd, and Pt) in surface sediments from a Brazilian subtropical estuary influenced by anthropogenic activities

The concentrations of Platinum (Pt), Rhodium (Rh) and Palladium (Pd) were evaluated from a highly impacted estuary in Brazil influenced by industrial pole, highway traffic and sewage outfall. The Santos-São Vicente region presents important economic activities derived from a largest harbor of Latin America and an industrial pole surrounded by intensive highway traffic. Values of Rh varied from 0.08 to 1.7 ng g^-1 with highest values at stations impacted by domestic waste. Pt ranged from 0.15 to 40.3 ng g^-1 with highest concentrations located close to the ferryboat traffic. Pd levels varied from 1.05 to 22.0 ng g^-1 with values >5 ng g^-1 in 50% of the stations. The spatial distribution of PGEs was not always directly associated with muddy sediments, because high PGE levels found even in sandy sediments. Pollution indexes, including anthropogenic factor (AF), geoaccumulation index (I_geo), Enrichment factor (EF), and Pollution Load Index (PLI) were used for evaluating contaminant potential. Based on EF, Igeo, and PLI, 50% of samples of the sediments from Santos-São Vicente Estuarine System (SSV) were classified with significant to strong PGE contamination. All stations on the Santos Channel (SC), São Vicente Channel (SVC) and Bertioga Channel (BC) had AF higher than 80% in at least one of PGE elements, as showed in station 2A, which presented AF <50% for Rh and Pd and 86% for Pt. Despite high anthropogenic enrichment, no correlations among PGE elements were observed in surface sediments. Only two stations presented Pd/Pt, Pt/Rh, and Pd/Rh typical ratios of auto catalyst (st. 14 and Piaçaguera) both located in the vicinity of highways. This could be due to the PGE deposition process in road dust, soil, and water as well as the biogeochemical cycling of PGEs involving organic metallic and inorganic complexes formed in the estuarine and seawaters.

Development and validation of DGT passive samplers for the quantification of Ir, Pd, Pt, Rh and Ru: A challenging application in waters impacted by urban activities

Platinum group elements (PGEs) are among the least abundant in the continental crust. They have become excellent tracers of anthropogenic activities, particularly due to their use in catalytic converters or in the medical industry. However, their quantification in environmental matrices is still problematic because of their low concentrations combined with the presence of interfering elements. Preconcentration methods are therefore necessary to measure accurate concentrations. In this study, the quantification of Ir, Rh, Ru, Pd and Pt was studied in depth by focusing on two resins: AG MP-1 (anion exchange) and Purolite® S-920 (chelating) with the aim of developing passive Diffusive Gradients in Thin films (DGT) samplers as in-situ pre-concentration tools. The characteristics of both resins (e.g. adsorption, elution, selectivity, etc.) were studied and the diffusion coefficients of PGEs in different matrices were determined. For the first time, carcinostatic platinum-based drugs were also studied. Better rates and percentages of adsorption were observed for S-920 while AG MP-1 was more selective with regard to spectral interferents and easier to elute. The diffusion coefficients of PGEs were resin-dependent, particularly for carcinostatic platinum-based drugs. For the first time, the applicability of these DGT samplers dedicated to PGEs was demonstrated in the field after their deployment in two wastewater treatment plants in Northern France for which concentrations were found to range from few pg L^-1 (Ir, Ru) to few ng L^-1 (Pt).

Bio-engineered palladium nanoparticles: model for risk assessment study of automotive particulate pollution on macrophage cell lines

The surge in vehicular activity in densely populated areas has led to an increased concentration of airborne palladium nanoparticles (PdNPs) in the environment. Recent toxicity data have indicated that PdNPs exhibit adverse effects in in vitro and in vivo models, however, their effect on the immune system is not fully understood. Therefore, in the present study, we aimed to evaluate possible toxic effects of bio-engineered palladium nanoparticles on the murine macrophage cell line (J774). Here we prepared palladium nanoparticles using aqueous leaf extract of Parthenium hysterophorus and characterized them by UV-Vis spectroscopy, XRD, FT-IR spectroscopy, HR-TEM, EDX, SEM and zeta potential. Toxicity parameters such as cell viability, cell membrane integrity, induction of apoptosis and ROS production were assessed on J774 cell lines. Spherical palladium nanoparticles of mean size ∼4 nm, when subjected to time and dose-dependent cytotoxicity assay, showed cell viability was >95% at lower doses (25, 200 μg mL-1) and <50% at higher doses of palladium nanoparticles (400, 500 μg mL-1) after 24 hours of incubation. We also observed cell membrane injury at higher doses by lactate dehydrogenase assay. The induction of apoptosis observed was moderate. H2DCFDA assay revealed visible cell damage which could be due to modest levels of ROS generation. The detection of Pd in the road-dust samples of New Delhi using inductively coupled plasma-mass spectroscopy (ICP-MS) technique was also investigated.

Comparative study on a kilowatt-MPT-MS-based method with two ion polarity modes for the inert palladium metal

Inert metals are of much importance and play a key role in modern industrial manufacturing. The analytical techniques of inert metals remain challenging. In particular, the mass spectrometry of inert metal elements is yet to be further developed, which also limits the contemporary conceptual in situ analysis of inert metals. As the representative element, the mass spectral detection of palladium is critical and of far-reaching significance. Herein, we developed a mass spectrometry method, which can be used for the high-speed and in situ analysis of palladium, and even for other inert metals. Combining the line ion trap mass spectrometer with the versatile ambient ionization source, a novel kilowatt microwave plasma torch (MPT) can be used to obtain the fully characteristic MPT mass spectra of palladium. Detailed multistage tandem mass spectra show that the general form of target ions is [M(O2)x(NO)mNy(NO2)n]- for the negative ion mode and [M(H2O)x(NO2)y(N2)m]+ for the positive ion mode. Moreover, the formation and evolution of these palladium complex ions were reasonably derived based on the analysis of MPT background mass spectra. This mass spectrometric technique is also suitable for the determination of the palladium-containing solution in the sub-trace level. Semi-quantitative results showed that the detecting ability for palladium in the negative mode is better than that of the positive mode. Under the negative ion mode, the limit of detection (LOD) for m/z 259 were evaluated to be 0.5 μg L-1 under the optimized conditions of the negative mode, with the linear range of 1-100 μg·L-1 (R2 ≥ 0.9985) and the relative standard deviation (RSD, n = 11) being in the range of 1.20%-5.98% (refer to Table S3). Our experimental data showed that MPT-MS was a promising technique for providing another alternative in the on-site analysis of liquid samples and other intimate relevant fields, as the supplement of ICP-MS for the detection of inert metal elements. On the other hand, this work will also certainly promote the more broad applications of platinum-group elements (PGE) in modern science and industry.

Review of the interactions between vehicular emitted potentially toxic elements, roadside soils, and associated biota

Given the large size of the world road network, the land area affected by vehicular emissions is extensive. This review provides the first global picture of the relationships between vehicular emitted potentially toxic elements, roadside soils, and risks to associated biota. The following potentially toxic elements that accumulate in roadside soils have been examined in this review: As, Co, Cr, Cu, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Se, Sb, Sn, Sr, Ti and Zn. The meta-analysis undertaken demonstrated an increase in concentrations of Cd, Pb, Zn, Pt, Pd and Rh in roadside soils compared to the mean global crustal concentrations. Positive correlations between potentially toxic element concentrations in roadside soil, plants, microbes, and animals were observed. Roadside studies have found increased potentially toxic element concentrations in plants and animals with increasing proximity to roads. The mean concentrations of Pb in roadside plants and vertebrates were at values above the World Health Organisation guidelines. Research has shown a range of impacts of potentially toxic elements in roadside soils on microbial activity including decreased litter decomposition, nitrogen fixation, nutrient cycling and enzyme synthesis. However, aside from the impact on microbial communities, there has been little research investigating the impacts of roadside soil elements on the associated biota. Thus, there is a need for research that investigates the toxicity of elements in roadside soils to plants and animals and to investigate the transfer of roadside elements through the food chain, and thus, risks posed to human health and the environment.

Method development for determination of trace amounts of palladium in environmental water samples by ICP-MS/MS after pre-concentration on thiol-functionalized MCM-41 materials

The anthropogenic cycle of Pd in the environment, its fate and impact is still unknown due to limitations of measurement techniques. For separation and pre-concentration of Pd(II) ions, mesoporous silica materials MCM-41 were synthesized and functionalized with different amounts of 3-mercaptopropyltrimethoxysilane (MPTMS) by co-condensation and grafting methods. The structural and textural properties of materials were characterized using XRD, TEM, SEM and BET techniques. The results proved that functionalization with thiol groups did not significantly affect structural and textural parameters of synthesized sorbents. The Pd(II) ions were quantitatively retained on sorbents functionalized by grafting in acidic solutions (pH 2), efficiently eluted with 0.1 mol L^-1 thiourea solution in 1 mol L^-1 HCl and determined by electrothermal atomic absorption spectrometry (ETAAS). The limit of detection (LOD) of the developed SPE ETAAS method was 0.06 ng mL^-1, and the pre-concentration factor was 30. For analysis of Pd in environmental water samples inductively coupled plasma mass spectrometry (ICP-MS) in MS/MS mode was used. Spectral interferences on ¹⁰⁵Pd caused by the presence of Sr in water samples were eliminated using helium (5 mL min^-1) or ammonia (7 mL min^-1) gas in collision/reaction cell. The developed SPE ICP-MS method is characterized by good selectivity in the presence of interfering elements and chloride ions and detection limit of 0.0002 ng mL^-1. Its accuracy was confirmed by analysis of spiked water samples. The application of ICP-MS together with efficient separation/pre-concentration of analyte on thiol-functionalized MCM-41 sorbents allows to determine Pd in environmental water samples at pg mL^-1 level.

V-shaped bis-coumarin based fluorescent probe for detecting palladium in natural waters

A catalytic fluorescent probe based on V-shaped bis-coumarin has been designed and synthesized for detection of palladium (Pd). The detection mechanism of the probe is based on palladium-catalyzed Tsuji‒Trost reaction process and photoinduced electron transfer (PET), which can distinguish and detect palladium (0, +2/+4) in different valence states under different conditions. The fluorescence intensity of the probe enhances after adding the palladium in about 10 min at room temperature. The limit of detection (LOD) of the probe is as low as 40.0 nM (4.2 ng/g), and it has good selectivity and high sensitivity. Apart from that, it has been successfully applied to detection of palladium in environmental waters.

Spatiotemporal variations of platinum in seawater in Otsuchi Bay, Japan after the 2011 tsunami

Huge tsunami waves devastated coastal areas on the Pacific Ocean side of northern Japan on March 11, 2011, and seriously damaged these coastal environments. Since the tsunami, we have not yet obtained data on the present state of and changes in trace metal concentrations in seawater in these areas. Platinum (Pt), one of the rarest elements in the Earth's crust, is now widely used in a range of products, such as catalytic converters in automobiles and anticancer drugs. Increasing use and dispersal of Pt has the potential to affect aquatic environments, although Pt concentrations in open ocean seawater have been found to be very low (approximately 0.2 pmol/L). In this study, we reveal the Pt concentrations in seawater and sediment in Otsuchi Bay after the tsunami, and evaluate the behavior of the Pt. The concentrations of dissolved Pt in seawater are 0.40-1.99 pmol/L and those in river water are below the detection limit of 0.015 pmol/L. Comparing the Pt concentrations in May, higher concentrations were obtained in 2013 than in 2012, especially in the deepest seawater. The total Pt concentrations in sediment samples were 0.46-14.4 ng/g in Otsuchi Bay. Using a sequential leaching technique on the sediments, Pt concentrations in the acetic-acid fractions were 0.19-1.13 ng/g, and those in the acetic acid + hydrochloric acid hydroxylamine fractions were less than 0.03-0.71 ng/g. Seasonal variations in dissolved Pt concentrations reflected changes in the water mass structure. During the stratification season, vertical profiles indicated that Pt concentrations tended to increase with depth due to supply from the sediments, whereas in winter, the water mass was vertically well mixed. The Pt was supplied to the bottom of the water from the sediments, probably due to loosely adsorbed Pt on sediment particles being remobilized during post-depositional processes. The increased internal input of Pt within Otsuchi Bay can be explained by the release of 1.3-5.6% of the leachable fraction from sediments, probably transported from the land by the tsunami, during the water residence time in the bay.

Mechanistic simulation of bioconcentration kinetics of waterborne Cd, Ag, Pd, and Pt in the zebra mussel Dreissena polymorpha

Mechanistic models based on chemical properties of metals and body size have received substantial attention for their potential application to various metals and to different conditions without required calibration. This advantage has been demonstrated for a number of metals, such as Cd and Ag. However, the capacity of metal-specific chemical properties to explain variations in the accumulation for platinum-group elements (PGEs) has not been investigated yet, although emission of these metals is of increasing concern. Once being released, PGEs exist in the environment in mixtures with other metals. The present study attempted to model the accumulation of Pd and Pt in mixtures with Ag and Cd in the zebra mussel (Dreissena polymorpha) from the aqueous phase; and to investigate the potential application of mechanistic models to Pd and Pt. The present study showed statistically insignificant differences in metal accumulation among size groups in a narrow range of shell length (16-22 mm). Kinetic models could simulate well the accumulation of Cd, Ag, and Pt when metal-specific responses of zebra mussels are taken into consideration. These responses include enhanced immobilisation as a detoxifying mechanism and exchange between soft tissues and shells via the extrapallial fluid. Environmental conditions, e.g. the presence of abiotic ligands such as chloride, might also play an important role in metal accumulation. Significant relationships between the absorption efficiency and the covalent index indicate the potential application of mechanistic models based on this chemical property to Pt.

Platinum group elements study in automobile catalysts and exhaust gas samples

Platinum-Group Elements (PGEs, i.e. platinum; Pt, palladium; Pd and rhodium; Rh) are extensively employed in the production of automotive catalytic converters to catalyze and control harmful emissions from exhaust fumes. But catalytic converters wear out over time and the emission of PGEs along with the exhaust fumes are nowadays known to be the main reason of the presence of PGEs in urban environments. PGEs contents were studied on three gasoline 3-way catalytic convertors with low, medium and high kilometers. PGEs emission factors via exhaust gases from Euro 3, 4, 5 and 6 gasoline and diesel vehicles, were monitored using catalytic converters. Results show variable content for PGEs for the three converters, in the ranges of 6-511, 0.5-2507 and 0.1-312 mg kg^-1 for Pt, Pd and Rh respectively. PGEs contents in different catalyst supports show the replacement of Pt by Pd in more recent converters. Analysis of the exhaust gas shows that catalytic converters expel up to 36.5 ± 3.8 ng km^-1 of Pt, 8.9 ± 1.1 ng km^-1 of Pd and 14.1 ± 1.5 ng km^-1 of Rh. Higher emissions of PGEs have been observed by gasoline Euro 3 vehicle, possibly due to the older technology of motorization and of the catalytic converter in this vehicle. Euro 3 and 4 diesel vehicles seem to emit more PGEs during urban cycles. Emission of PGEs has been also observed during the cold start of the majority of vehicles which seems to be the result of incomplete combustion during the rise of temperature in the engine. Higher PGEs emissions were also observed during motorway cycles in newer (Euro 4 and 5) petrol and diesel vehicles, conceivably due to the greater combustion as the engine speeds up during this cycle.

The HR-CS-GF-AAS determination and preconcentration of palladium in contaminated urban areas, especially in lichens

The increasing content of platinum group metal particles emitted into the environment by car traffic is gradually attracting the attention of the scientific community. However, the methods for the determination of platinum group metals in environmental matrices are either costly or suffer from low sensitivity. To facilitate the use of less sensitive, but significantly cheaper, devices, the preconcentration of platinum group metals is employed. For platinum, a multitude of preconcentration approaches have been published. On the contrary, the preconcentration approaches for palladium are still rare. In this work, the development, optimization, and testing of a new approach is described; it is based on a preconcentration of palladium on octadecyl modified silica gel together with the complexing agent dimethylglyoxime, and it is then analyzed with the high-resolution continuum-source atomic absorption spectrometry. For comparison, a newly developed sorbent, QuadraSil™ TA, with a high affinity for platinum group metals was also tested. The preconcentraiton approach was tested on the lichen Hypogymnia physodes, which served as a bioindicator of palladium emissions. The case study site was a mid-sized city in central Europe: Brno, Czech Republic. The dry "bag" monitoring technique was used to collect the palladium near roads with a large span of traffic density. The developed analytical approach confirmed an increasing concentration of palladium with increasing exposure time and intensity of the traffic. Consequently, a simple relationship between the amount of bioaccumulated palladium and traffic density was established.

Toxicity assessment of palladium oxide nanoparticles derived from metallosurfactants using multi assay techniques in Allium sativum

In today's world, nanotechnology is reaching practically every ground and entering the human lifestyle by becoming a part of it. Thus, it is vital to check the cytotoxic and genotoxic effects of nanosubstances on plants, as they are the base constituent of ecosystem. The present work deals with the toxicity evaluation of metallosurfactant derived palladium oxide nanoparticles towards Allium sativum (Garlic cloves). The nanoparticles were prepared using microemulsion quenching method (a softer approach) using palladium metallosurfactants as precursors. The three ligands used were cetyltrimethylammonium chloride (CTAC), dodecylamine (DDA) and hexadecylamine (HEXA). Further, their characterization was done using TEM, Size Distribution curve, FESEM, EDS, XRD and Zeta potential. Garlic (Allium sativum) cloves were used to investigate the cytotoxicity and genotoxicity of fabricated PdO NPs. To check the cytotoxicity, optical microscopy was employed and for the genotoxic assessment, different parameters such as chromosomal aberrations in the mitosis, circular dichroism, and gel electrophoresis were utilized. From mitosis study, chromosomes aberrations were confirmed such as chromosomes stickiness, breakage, C-Mitosis, delay in anaphase, spindle fibre abnormality, laggard, vagrant and condensed chromosomes. Morphology of A. sativum clove, rooting and shooting pattern in the presence of PdO nanosuspension was observed. From all the experiments, it was concluded that all the three PdO nanosuspension are toxic in nature to both the cells and to genome, although, bishexadecyltrimethyl ammonium palladium tetrachloride (PdCTAC) Ns was found to be the most cytotoxic and genotoxic. Gel electrophoresis also confirmed the complete degradation of DNA in the presence of PdCTAC Ns.

Heavy metal contamination in urban surface sediments: sources, distribution, contamination control, and remediation

Urban road sediments act as large basins for heavy metal contaminants produced as a result of natural processes and anthropogenic activities. This study is aimed at reviewing research over recent decades on heavy metal contamination in different cities around the world. The study reviews literature from Google Scholar, Web of Science, and Scopus journal publications. Cr, Cu, Pb, Zn, Ni, and Cd levels vary from one city to another. Based on the collected results, the pollution level and geoaccumulation index are estimated in each city. The levels of pollution in these cities range from low to extremely high, depending on the sources of pollution at each site (geogenic and anthropogenic sources, etc.) and factors like the distribution of industrial activities, population, and traffic emissions. This review shows that the development of modern cities and rapid urbanization are the major causes of heavy metal contamination in the environment. The contamination of the urban environment has different sources, both natural and anthropogenic in character. Solving the problem of heavy metal contamination in the urban environment requires the use of different techniques such as urban road control treatment and soil remediation.

A Near-infrared Fluorescent Probe of Dicyanoisophorone Derivatives for Selective Detection and Fluorescence Cellular Imaging of Palladium

Palladium (Pd) has been acknowledged to be a rare inner transition metal, which plays a pivotal role in many fields. This article focuses on developing a safe and effective near-infrared fluorescent probe, MW-PD, which would make a great contribution to the detection of palladium residue in drugs, especially trace residues. The fluorescent probe was rationally designed by combining the dicyanoisophorone fluorophore with an allyloxycarbonyl group. Based on the Tsuji-Trost reaction, the probe exhibited high selectivity and sensitivity toward Pd (0) over other common metal ions with a low detection limit (8.0 nM). Moreover, MW-PD showed biocompatibility and was successfully applied to imaging Pd (0) in Hela cells.

Investigating the Integrity of Graphene towards the Electrochemical Hydrogen Evolution Reaction (HER)

Mono-, few-, and multilayer graphene is explored towards the electrochemical Hydrogen Evolution Reaction (HER). Careful physicochemical characterisation is undertaken during electrochemical perturbation revealing that the integrity of graphene is structurally compromised. Electrochemical perturbation, in the form of electrochemical potential scanning (linear sweep voltammetry), as induced when exploring the HER using monolayer graphene, creates defects upon the basal plane surface that increases the coverage of edge plane sites/defects resulting in an increase in the electrochemical reversibility of the HER process. This process of improved HER performance occurs up to a threshold, where substantial break-up of the basal sheet occurs, after which the electrochemical response decreases; this is due to the destruction of the sheet integrity and lack of electrical conductive pathways. Importantly, the severity of these changes is structurally dependent on the graphene variant utilised. This work indicates that multilayer graphene has more potential as an electrochemical platform for the HER, rather than that of mono- and few-layer graphene. There is huge potential for this knowledge to be usefully exploited within the energy sector and beyond.

A chemical speciation insight into the palladium(ii) uptake and metabolism by Sinapis alba. Exposure to Pd induces the synthesis of a Pd-histidine complex

Palladium is recognized as a technologically critical element (TCE) because of its massive use in automobile exhaust gas catalytic converters. The release of Pd into the environment in the form of nanoparticles of various size and chemical composition requires an understanding of their metabolism by leaving organisms. We provide here for the first time a chemical speciation insight into the identity of the ligands produced or used by a plant Sinapis alba L. exposed in hydropony to Pd nanoparticles and soluble Pd (nitrate). The analytical method developed was based on the concept of 2D HPLC with parallel inductively coupled plasma mass spectrometry (ICP MS) and electrospray MS detection. Size exclusion chromatography - ICP MS of the plant extracts showed no difference between the speciation of Pd after the exposure to nanoparticles and after that to Pd²⁺ which indicated the reactivity and dissolution of Pd nanoparticles. A comparative investigation of the Pd speciation in a control plant extract spiked with Pd²⁺ and of an extract of a plant having metabolized palladium indicated the response of the Sinapis alba by the formation of a Pd-histidine complex. The complex was identified via Orbitrap MS; the HPLC-MS chromatogram produced two peaks at m/z 415.0341 each corresponding to a Pd-His₂ complex. An investigation by ion-mobility MS revealed a difference in their collision cross section indicating that the complexes present varied in terms of spatial conformation. A number of other Pd complexes with different ligands (including nicotianamine) circulating in the plant were detected but these ligands were already observed in a control plant and their concentrations were not affected by the exposure to Pd.

Platinum and rhodium in Tagus estuary, SW Europe: sources and spatial distribution

The spatial distribution of Pt and Rh was assessed in Tagus estuary and their sources discussed. Both elements were analysed in superficial sediment samples (n = 72) by adsorptive cathodic stripping voltammetry. Concentrations varied within the following ranges: 0.18-5.1 ng Pt g^-1 and 0.02-1.5 ng Rh g^-1. Four distinct areas were established: "reference"; waste- and pluvial water discharge; motorway bridges and industrialised areas. The calculated reference median concentrations were 0.55 ng Pt g^-1 and 0.27 ng Rh g^-1. Linear relationships were found between Pt and Al, Fe and LOI, whereas Rh depicted scattered patterns. The highest concentrations were found nearby industrialised areas and a motorway bridge, corresponding to the enrichment of 10 and 6 times the background of Pt and Rh, respectively. The main sources of contamination to the Tagus estuary derived from historical and present industrial activities and from automotive catalytic converters. Large variations of Pt/Rh ratio (0.48-39) point to different sources, reactivity and dilution effects.

Genomic and Transcriptomic Changes that Mediate Increased Platinum Resistance in Cupriavidus metallidurans

The extensive anthropogenic use of platinum, a rare element found in low natural abundance in the Earth's continental crust and one of the critical raw materials in the EU innovation partnership framework, has resulted in increased concentrations in surface environments. To minimize its spread and increase its recovery from the environment, biological recovery via different microbial systems is explored. In contrast, studies focusing on the effects of prolonged exposure to Pt are limited. In this study, we used the metal-resistant Cupriavidus metallidurans NA4 strain to explore the adaptation of environmental bacteria to platinum exposure. We used a combined Nanopore⁻Illumina sequencing approach to fully resolve all six replicons of the C. metallidurans NA4 genome, and compared them with the C. metallidurans CH34 genome, revealing an important role in metal resistance for its chromid rather than its megaplasmids. In addition, we identified the genomic and transcriptomic changes in a laboratory-evolved strain, displaying resistance to 160 µM Pt4+. The latter carried 20 mutations, including a large 69.9 kb deletion in its plasmid pNA4_D (89.6 kb in size), and 226 differentially-expressed genes compared to its parental strain. Many membrane-related processes were affected, including up-regulation of cytochrome c and a lytic transglycosylase, down-regulation of flagellar and pili-related genes, and loss of the pNA4_D conjugative machinery, pointing towards a significant role in the adaptation to platinum.

Synthesis, characterization, and environmental behaviors of monodispersed platinum nanoparticles

The release of platinum group elements, including platinum nanoparticles (PtNPs), has been increasing over recent decades. However, few studies have investigated the fate, behavior and effects of PtNPs in environmental media. Here, we report a protocol for the synthesis of five different sizes (8.5 ± 1.2, 10.3 ± 1.3, 20.0 ± 4.8, 40.5 ± 4.1, and 70.8 ± 4.2 nm) of monodispersed citrate- and polyvinylpyrrolidone (PVP)-coated PtNPs, together with a characterization of their behaviors using a multi method approach in relevant biological and toxicological media. In general, PtNPs sizes measured using dynamic light scattering, field flow fractionation, single-particle inductively-coupled plasma-mass spectroscopy, transmission electron microscopy and atomic force microscopy, were all in good agreement when PtNP sizes were larger than the size detection limits of each analytical technique. Slight differences in sizes measured were attributable to differences in analytical techniques, measuring principles, NP shape and NP permeability. The thickness of the PVP layer increased (from 4.4 to 11.35 nm) with increases in NP size. The critical coagulation concentration of cit-PtNPs was independent of NP size, possibly due to differences in PtNPs surface charges as a function of NP size. PtNPs did not undergo significant dissolution in any media tested. PtNPs did not aggregate significantly in Dulbecco's modified Eagle's medium; but they formed aggregates in moderately hard water and in 30 ppt synthetic seawater, and aggregate size increased with increases in PtNPs concentration. Overall, this study describes a general model NP system (i.e., PtNPs) of different controlled NP sizes and coatings that is predictable, stable and useful to investigate the fate, behavior, uptake, and eco-toxicity of NPs in the environment.

Simple fabrication of a carbaldehyde based fluorescent “turn-on” probe for the selective and sole detection of Pd2+: application as test strips

A simple fluorescent “turn-on” probe (DHMC) has been designed for selective and sole detection of Pd²⁺.

A colorimetric and “off–on” fluorescent Pd2+ chemosensor based on a rhodamine-ampyrone conjugate: synthesis, experimental and theoretical studies along with in vitro applications

We successfully designed and developed a rhodamine based “turn-on” chemosensor L for the detection of Pd²⁺ ions down to 1.19 × 10⁻⁵ M (11.9 μM).

Placental concentrations of essential, toxic, and understudied metals and relationships with birth outcomes in Chattanooga, TN

BACKGROUND

Comprehensive examinations of placental metal concentrations and correlations with infant parameters are under-investigated. Chattanooga, Tennessee's consistently high incidence of low birth weight and potential for metal exposure provides an ideal opportunity to investigate potential correlations.

OBJECTIVES

To investigate the associations between a wide variety of metals in placental tissue and multiple infant parameters.

METHODS

A total of 31 elements were screened via ICP-MS in 374 individual placental samples. Of those, 14 were quantifiable in > 86% of the samples. We examined correlations between metal concentrations and infant parameters (birth weight, gestational age, birth weight centile, placental weight, birth length and head circumference). We fit multivariable regression models to estimate the covariate-adjusted associations of birth weight with ln-transformed concentrations of each of the 14 metals and used generalized additive models to examine nonlinear relationships.

RESULTS

Some of the strongest relationships with infant parameters came from several lesser-studied metals. Placental rhodium concentrations were negatively correlated with almost all infant parameters. In the fully adjusted regression model, birth weight was significantly associated with several metals. On an IQR (25th to the 75th percentile) basis, estimated changes in birthweight were: for cobalt (82.5 g, IQR=6.05 µg/kg, p = 0.006), iron (-51.5 g, IQR = 171800 µg/kg, p = 0.030), manganese (-27.2 g, IQR=152.1 µg/kg, p = 0.017), lead (-72.7 g, IQR=16.55 µg/kg, p = 0.004) and rhodium (-1365.5 g, IQR = 0.33 µg/kg, p < 0.001). Finally, a generalized additive model showed significant nonlinear relationships between birth weight and concentrations of Co and Rh.

CONCLUSIONS

Our comprehensive examination of placental metals illustrate many strong associations between lesser-studied metals and infant parameters. These data, in combination with our correlations of well-studied metals, illustrate a need to consider in utero exposure to a broad array of metals when considering fetal development.

Rational design of a boron-dipyrromethene-based fluorescent probe for detecting Pd2+ sensitively and selectively in aqueous media

A novel fluorescent probe for Pd²⁺ based on the BODIPY fluorophore exploiting the PET (Photoinduced Electron Transfer) mechanism was designed and successfully synthesized.

Monitoring of the Palladium Concentration in River Water and Sediment at an Acidic Hot Spring Spa Area in Gunma Prefecture

In an effort to elucidate the deposition pathway of Pd in river sediments, we analyzed the amount of Pd in the river water and sediments of the Yukawa and Yazawa rivers, as well as in the sediments of the Shinaki dam-lake of the Kusatsu hot-spring area, which is located northwest in Gunma Prefecture of Japan. The crystal structures and elemental compositions of the river sediment samples differed significantly before and after neutralization. This was attributed to the lime input, which also affected the Pd abundance ratio obtained by the sequential extraction procedure. Additionally, the low leachability of Pd in the sediment suggested possible difficulties in its recovery. Considering the analysis of the Pd variation in the environments, it was concluded that the Pd content in the sediment of the Shinaki dam-lake was mainly supplied by the Yukawa river water inflowing the surrounding tributary rivers and hot-spring waters before neutralization, rather than the lime input.

Determination of ultra-trace Pt, Pd and Rh in seawater using an off-line pre-concentration method and inductively coupled plasma mass spectrometry

A method was modified for the preconcentration of platinum (Pt), palladium (Pd) and rhodium (Rh) from seawater by a solid phase extraction using a commercially available resin Nobias-chelate PA1^®. All the determination was conducted using inductively coupled plasma mass spectrometry (ICP-MS) which had a low detection limit for Pt, Pd and Rh, about 16.53, 16.41 and 26.88 pg L^-1, respectively. It was found that the adsorption performance of the resin was closely related to the matrix, ligands and pH of the samples. Significant difference in recovery was found in various samples: seawater ≈ artificial seawater > ultra-pure deionized water. This method had low method blank in the range of 5.51-8.89 pg L^-1 and high enrichment factor of up to 180-200. The recoveries of Pt and Pd were 93 ± 4.2% in the spiked real seawater. However, the recovery of Rh on the resin was below 70% but stable in the range of 65-68%. It indicated that the Rh recovery seemed to be reproducible and higher volumes of seawater must be processed in order to obtain the lower limit of quantification and excellent recovery.

Metallothionein: An Aggressive Scavenger-The Metabolism of Rhodium(II) Tetraacetate (Rh2(CH3CO2)4)

Anthropogenic sources of xenobiotic metals with no physiological benefit are increasingly prevalent in the environment. The platinum group metals (Pd, Pt, Rh, Ru, Os, and Ir) are found in marine and plant species near urban sources, and are known to bioaccumulate, introducing these metals into the human food chain. Many of these metals are also being used in innovative cancer therapy, which leads to a direct source of exposure for humans. This paper aims to further our understanding of nontraditional metal metabolism via metallothionein, a protein involved in physiologically important metal homeostasis. The aggressive reaction of metallothionein and dirhodium(II) tetraacetate, a common synthetic catalyst known for its cytotoxicity, was studied in detail in vitro. Optical spectroscopic and equilibrium and time-dependent mass spectral data were used to define binding constants for this robust reaction, and molecular dynamics calculations were conducted to explain the observed results.

Size-dependent genotoxicity of silver, gold and platinum nanoparticles studied using the mini-gel comet assay and micronucleus scoring with flow cytometry

Metallic nanoparticles (NPs) are promising nanomaterials used in different technological solutions as well as in consumer products. Silver (Ag), gold (Au) and platinum (Pt) represent three metallic NPs with current or suggested use in different applications. Pt is also used as vehicle exhaust catalyst leading to a possible exposure via inhalation. Despite their use, there is limited data on their genotoxic potential and possible size-dependent effects, particularly for Pt NPs. The aim of this study was to explore size-dependent genotoxicity of these NPs (5 and 50 nm) following exposure of human bronchial epithelial cells. We characterised the NPs and assessed the viability (Alamar blue assay), formation of DNA strand breaks (mini-gel comet assay) and induction of micronucleus (MN) analysed using flow cytometry (in vitro microflow kit). The results confirmed the primary size (5 and 50 nm) but showed agglomeration of all NPs in the serum free medium used. Slight reduced cell viability (tested up to 50 µg/ml) was observed following exposure to the Ag NPs of both particle sizes as well as to the smallest (5 nm) Au NPs. Similarly, at non-cytotoxic concentrations, both 5 and 50 nm-sized Ag NPs, as well as 5 nm-sized Au NPs, increased DNA strand breaks whereas for Pt NPs only the 50 nm size caused a slight increase in DNA damage. No clear induction of MN was observed in any of the doses tested (up to 20 µg/ml). Taken together, by using the comet assay our study shows DNA strand breaks induced by Ag NPs, without any obvious differences in size, whereas effects from Au and Pt NPs were size-dependent in the sense that the 5 nm-sized Au NPs and 50 nm-sized Pt NPs particles were active. No clear induction of MN was observed for the NPs.

Spectroscopic and Voltammetric Analysis of Platinum Group Metals in Road Dust and Roadside Soil

The emission of toxic compounds by increasing anthropogenic activities affects human health and the environment. Heavy road traffic and mining activities are the major anthropogenic activities contributing to the presence of metals in the environment. The release of palladium (Pd), platinum (Pt), and rhodium (Rh) into the environment increases the levels of contamination in soils, road sediments, airborne particles, and plants. These Pd, Pt, and Rh in road dusts can be soluble and enter aquatic environment posing a risk to environment and human health. The aim of this study is to determine the levels of Pd, Pt, and Rh with spectroscopy and voltammetric methods. Potential interferences by other metal ions (Na(I), Fe(III), Ni(II), Co(II)) in voltammetric methods have also been investigated in this study. At all the sampling sites very low concentrations of Pd, Pt, and Rh were found at levels that range from 0.48 ± 0.05 to 5.44 ± 0.11 ng/g (dry weight (d.wt)) for Pd(II), with 17.28 ± 3.12 to 81.44 ± 3.07 pg/g (d.wt) for Pt(II), and 14.34 ± 3.08 to 53.35 ± 4.07 pg/g (d.wt) for Rh(III). The instrumental limit of detection for Pd, Pt, and Rh for Inductively Coupled Plasma Quadrupole-based Mass Spectrometry (ICP-QMS) analysis was found to be 3 × 10−6 µg/g, 3 × 10−6 µg/g and 1 × 10−6 µg/g, respectively. In the case of voltammetric analysis the instrumental limit of detection for Pd(II), Pt(II), and Rh(III) for differential pulse adsorptive stripping voltammetry was found to be 7 × 10−8 µg/g, 6 × 10−8 µg/g, and 2 × 10−7 µg/g, respectively. For the sensor application, good precision was obtained due to consistently reproduced the measurements with a reproducibility of 6.31% for Pt(II), 7.58% for Pd(II), and 5.37% for Rh(III) (n = 10). The reproducibility for ICP-QMS analysis were 1.58% for Pd(II), 1.12% for Pt(II), and 1.37% for Rh(III) (n = 5). In the case of repeatability for differential pulse adsorptive stripping voltammetry (DPAdSV) and ICP-QMS, good standard deviations of 0.01 for Pd(II); 0.02 for Pt(II), 0.009 for Rh(III) and 0.011 for Pd, 0.019 for Pt and 0.013 for Rh, respectively.

Spatial and temporal distribution of platinum, palladium and rhodium in Zagreb air

Platinum (Pt), palladium (Pd) and rhodium (Rh) are most widely used in the production of automotive catalytic converters that serve to reduce toxic emissions from motor vehicles. The aim of this study was to quantitatively determine the levels of platinum, palladium and rhodium in the PM₁₀ and PM_2.5 fraction of airborne particle matter and find their spatial and temporal distribution at different polluted areas of the city of Zagreb, Croatia. The method used in this paper included weekly sampling of airborne particle matter on quartz filters, microwave digestion in acid under high pressure and temperature, and analysis by inductively coupled plasma mass spectrometry (ICP MS). The results have shown that the highest mean values at all three sampling stations (North, Center, South) were obtained for palladium (3.856 pg m^-3, 5.396 pg m^-3, 5.600 pg m^-3) and the lowest for rhodium (0.444 pg m^-3, 0.643 pg m^-3, 0.750 pg m^-3). The average mass concentrations of platinum group elements (PGE) in PM₁₀ increased for all three elements in the direction North < Center < South which had to do with the traffic load nearby the monitoring stations. The ratio of measured mass concentrations to all measuring stations was similar to platinum, palladium and rhodium content in automotive catalytic converters. Factor analysis grouped platinum, palladium and rhodium at all of the monitoring stations, and their relation to other metals together with the aforementioned results indicate that their main source of pollution is traffic or precisely automotive catalytic converters. At all three of the monitoring sites, higher values were measured during the colder part of the year. The results of measuring platinum, palladium and rhodium levels in the city of Zagreb are the first results of their kind for this area and will provide insights into the contribution of catalytic converters to the presence of these elements in the environment.

The impact of occupational exposure to traffic-related air pollution among professional motorcyclists from Porto Alegre, Brazil, and its association with genetic and oxidative damage

Vehicles play an important role in modern life; however, they also generate hazards. Occupational exposed subjects are in long-term contact with harmful products, which sets these professionals in a susceptible group to air pollutant damage. The aims of this study were to quantify individual exposure to pollutant gases and chemical elements and to evaluate oxidative and genetic damage in professional motorcyclists and office workers. We recruited professional motorcyclists and office workers from Porto Alegre, Brazil, between January and December 2016. Individual exposure to air pollutants was assessed by passive monitoring. Fingernail trace elements were determined by using inductively coupled plasma mass spectrometry. Oxidative stress biomarkers were quantified spectrophotometrically, and genotoxicity was evaluated by micronuclei assay. Individual exposure to NO₂ and O₃, trace element content (Sb, Pt, As, Cd, V, Mn, and Co), oxidative stress factors, and genetic damage were statistically higher in professional motorcyclists (p < 0.05). Moreover, NO₂ and O₃ levels showed very strong positive correlation with plasmatic lipid peroxidation (p < 0.001 and r = 0.8849 and 0.8995) and strong positive correlation with micronuclei frequency (p < 0.001 and r = 0.7683 and 0.7280). Results suggest that professional motorcyclists are at high risk due to long-term air pollution exposure, which implies in the onset of several harmful effects and worsening of pre-existent diseases.

Adsorption of platinum ion from "aged" aqueous solution: application and comparative study between purified MWCNTs and triphenylphosphine MWCNTs

This study entails adsorption attempt of platinum ion from "aged" aqueous solution with purified multiwalled carbon nanotubes and tryphenylphosphine-linked multiwalled carbon nanotubes (1) and (2) (Tpp-MWCNTs (1) and Tpp-MWCNTs (2)). The aims were to produce and use purified MWCNTs, Tpp-MWCNTs (1) and (2) and compare their adsorption capacity. These adsorbents were characterised with SEM, FTIR, XPS, BET and zeta potential. Tpp-MWCNTs (1) and (2) differ by their atomic percentage content of phosphorus which is 0.7 and 2.6%, respectively. A commercial stock solution (1000 mg/L) of platinum was used for the batch adsorption experiments. The data revealed that the adsorption was dependent on the following parameters: pH, contact time and initial concentration. The adsorbents attained higher adsorption capacity at pH 2 with an initial concentration of 7.9 mg/L, adsorbent dose of 0.8 g/L, contact time of 60 min at room temperature (RT), whereas 48.25, 40.06 and 41.31 mg/g were adsorbed from 20 mg/L by purified MWCNTs, Tpp-MWCNTs (1) and (2), respectively. The results are quite interesting and show that purified MWCNTs are better than Tpp-MWCNTs under the experimental conditions. The data was best described by the Langmuir model and the adsorption process occurs on the surface monolayer of the adsorbents. The isotherm studies confirmed that the adsorption of platinum ion is favourable. The findings indicate that the practical adsorption of platinum ion using the adsorbents investigated is useful.

Application of double-focusing sector field ICP-MS for determination of ultratrace constituents in samples characterized by complex composition of the matrix

The performance of double focusing, sector field mass spectrometry (ICP-SFMS) for determination of analytes, including technology critical elements (TCE), at ultra-trace levels in environmental and clinical matrices was critically evaluated. Different configurations of the ICP-SFMS introduction system as well as various sample preparations, pre-concentration and matrix separation methods were employed and compared. Factors affecting detection capabilities and accuracy of data produced (instrumental sensitivity, contamination risks, purity of reagents, spectral interferences, matrix effects, analyte recovery and losses) were discussed. Optimized matrix-specific methods were applied to a range of reference and control materials (riverine, brackish and seawaters; whole blood, serum and urine) as well as tap water and snow samples collected in the area of Luleå city, northern Sweden; brackish and seawater from the Laptev Sea; venous blood samples with a special emphasis on determination of Au, Ag, Ir, Os, Pd, Pt, Re, Rh, Ru, Sb and Te. Even though these low abundant elements are relatively under-documented, the results produced were compared with published data, where available.

Road dust and its effect on human health: a literature review

The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words "road dust" and "health" or "fugitive dust" and "health" in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure.

Road dust and its effect on human health: a literature review

The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words “road dust” and “health” or “fugitive dust” and “health” in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure.

Identification of platinum nanoparticles in road dust leachate by single particle inductively coupled plasma-mass spectrometry

Elevated platinum (Pt) concentrations are found in road dust as a result of emissions from catalytic converters in vehicles. This study investigates the occurrence of Pt in road dust collected in Ghent (Belgium) and Gothenburg (Sweden). Total Pt contents, determined by tandem ICP-mass spectrometry (ICP-MS/MS), were in the range of 5 to 79ngg^-1, comparable to the Pt content in road dust of other medium-sized cities. Further sample characterization was performed by single particle (sp) ICP-MS following an ultrasonic extraction procedure using stormwater runoff for leaching. The method was found to be suitable for the characterization of Pt nanoparticles in road dust leachates. The extraction was optimized using road dust reference material BCR-723, for which an extraction efficiency of 2.7% was obtained by applying 144kJ of ultrasonic energy. Using this method, between 0.2% and 18% of the Pt present was extracted from road dust samples. spICP-MS analysis revealed that Pt in the leachate is entirely present as nanoparticles of sizes between 9 and 21nm. Although representing only a minor fraction of the total content in road dust, the nanoparticulate Pt leachate is most susceptible to biological uptake and hence most relevant in terms of bioavailability.