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The interaction between environmental plastic and trace elements is an issue of concern. Understanding their interaction mechanisms is key to evaluate the potential threats for the environment. To this regard, consolidating confidence in extraction protocols can help in understanding the amount of different species present on plastic surface, as well as the potential mobility of trace elements present inside the plastic matrix (e.g., additives). Here we tested the efficacy of different reagents to mimic the elemental phases bonded to meso- and microplastic in the environment, in relation to the grade of ageing and the polymer composition. Results showed that a relatively high portion of trace elements is bonded in a weak phase and that other phases abundant in other matrices (e.g., oxides and bonded to organic matter) are only present to a limited degree in the plastic samples. The comparison of different sample types highlighted the important role of plastic ageing in governing interactions with trace elements, while the polymer composition has a limited influence on this process. Finally, the future steps toward a tailored extraction scheme for environmental plastic are proposed.

Mercury is one of the most toxic heavy metals. By virtue of its triple bond, the novel ligand 1,2-bis(1H-pyrazol-4- yl)ethyne (H2BPE) was expressly designed and synthesized to devise metal−organic frameworks (MOFs) exhibiting high chemical affinity for mercury. Two MOFs, Zn(BPE) and Zn(BPE)·nDMF [interpenetrated i-Zn and noninterpenetrated ni-Zn·S, respectively; DMF = dimethylformamide], were isolated as microcrystalline powders. While i-Zn is stable in water for at least 15 days, its suspension in HgCl2 aqueous solutions prompts its conversion into HgCl2@ni-Zn. A multitechnique approach allowed us to shed light onto the observed HgCl2-triggered i-Zn-to- HgCl2@ni-Zn transformation at the molecular level. Density functional theory calculations on model systems suggested that HgCl2 interacts via the mercury atom with the carbon−carbon triple bond exclusively in ni-Zn. Powder X-ray diffraction enabled us to quantify the extent of the i-Zn-to-HgCl2@ni-Zn transition in 100−5000 ppm HgCl2 (aq) solutions, while X-ray fluorescence and inductively coupled plasma-mass spectrometry allowed us to demonstrate that HgCl2 is quantitatively sequestered from the aqueous phase. Irradiating at 365 nm, an intense fluorescence is observed at 470 nm for ni-Zn·S, which is partially quenched for i-Zn. This spectral benchmark was exploited to monitor in real time the i-Zn-to-HgCl2@ni-Zn conversion kinetics at different HgCl2 (aq) concentrations. A sizeable fluorescence increase was observed, within a 1 h time lapse, even at a concentration of 5 ppb. Overall, this comprehensive investigation unraveled an intriguing molecular mechanism, featuring the disaggregation of a water-stable MOF in the presence of HgCl2 and the self-assembly of a different crystalline phase around the pollutant, which is sequestered and simultaneously quantified by means of a luminescence change. Such a case study might open the way to new-conception strategies to achieve real-time sensing of mercury-containing pollutants in wastewaters and, eventually, pursue their straightforward and costeffective purification., University of Insubria for partial funding, Programa Juan de la Cierva Formación (FJC2020-045043-I), MCIN/AEI/10.13039/501100011033, European Union NextGenerationEU/PRTR (Grants PID2020- 113608RB-I00 and TED2021-129886B-C41)

The mechanism, the effectiveness, and the potential damage during limewash removal from wall painting models were evaluated for agar gels and water-based pads constituted by ArbocelTM BWW 40 cellulosic fibre. Cleaning materials in different formulations were compared: pure and with additives (ethylenediaminetetraacetic acid, EDTA, and ammonium citrate tribasic, TAC) in different percentages (2% and 3%). The cleaning action was evaluated on laboratory model samples, prepared with hematite a fresco and an egg-based tempera with limewash overlayers. Calcium and iron extracted by cleaning materials were quantified by inductively coupled plasma-mass spectrometry (ICP-MS). The potential damage to the hematite painting layers was also studied by electron paramagnetic resonance (EPR) spectroscopy. A visual observation of the limewash detachment induced by the overall cleaning was also performed. Results suggest that limewash removal mainly occurs by aqueous solution release from the cleaning system, with subsequent layer wetting, probable layer swelling, weakening and complete or partial detachment. A stronger limewash adhesion on the hydrophilic fresco surface than on tempera, was observed. None of the used cleaning materials resulted harmful to the integrity of the hematite layer underneath the limewash. A small damage in terms of extracted iron was detected in the cleaning systems after direct contact with fresco and tempera hematite layers; a “protective” effect by the tempera layer was observed for the pigment, due to the organic binder and triggered by the hydrophobic content of the egg-based medium. Cleaning materials with additives are more harmful than pure materials, with a greater coordinating ability for EDTA than for TAC, which increases with chelator percentage. Data suggest a more efficient backward transportation of aqueous solutions containing calcium and iron ions towards gels with respect to cellulose, due to their smallest pore size. All these results lead to operative suggestions: for fresco painting layers, pure gel allows both a good limewash removal and a lack of damage on the hematite layers. Instead, for tempera layers a good limewash removal and a negligible damage on the pigment was shown by gel, both pure and additivated with TAC, and pure cellulose. Therefore, the present study allows to identify proper characterization methods for evaluating effectiveness and damage in limewash removal and to give useful suggestions for the planning of repeated cleaning operations on a real polychrome object.

Iron speciation analysis in seawater is a fundamental step to understand the cycling of this element in oceanic waters, in view of its central role in regulating primary productivity and its connection to global planetary cycles. At present, analytical procedures are the bottleneck for speciation analysis, in term of both time and sample size requirement. Here we present a novel instrumental configuration for the speciation analysis of iron by the Competitive Ligand Equilibration - Cathodic Stripping Voltammetry (CLE-CSV) procedure. The new system features a 1 mL microcell and a silver wire pseudoreference enabling a tenfold reduction of the sample volume. 2,3-dihydroxynaphthalene was used as the complexing ligand and atmospheric oxygen as the catalytic enhancer because they ensured the best analytical performances in terms of detection capabilities. The side reaction coefficient for the FeDHN complex αFe’DHN was calibrated against EDTA and an average value of 9.25 for logK’Fe’DHN was calculated. The method was successfully validated in UV digested seawater using diethylenetriaminepentaacetic acid (DTPA), which has known stability constant for iron. The method was lastly applied to six samples from the Ross Sea water column (Antarctica), demonstrating its fit for purpose for the detection of trace amounts of iron ligands in seawater. Thanks to the employed instrumental configuration and the high sensitivity, the proposed method achieved a tenfold reduction in sample size, a tenfold increase in sensitivity compared with other methods employing DHN and halved the analysis time with respect to the fastest method reported in the literature. Half an hour is enough to measure a 12 point titration, making the analysis of at least three titrations per day feasible. It is expected that the application of this procedure will foster the sample throughput, thanks to the reduced analysis time, and make possible the analysis of limitedly available and challenging samples, like porewater and vent fluids via the tenfold reduction in sample size.

Maternal exposure to air pollutants has been associated with pregnancy complications and adverse birth outcomes. Endothelial dysfunction, an imbalance in vascular function, during pregnancy is considered a key element in the development of pre-eclampsia. Environmental exposure to particulate matter (PM) during the first trimester of pregnancy might increase maternal inflammatory status thus affecting fetal growth, possibly leading to preterm delivery.The purpose of the study was to evaluate possible effects of PM295 pregnant women were recruited. Individual PM exposure was assigned to each subject by calculating the mean of PMFor long-term exposure, we observed an increase in sVCAM-1 and a decrease of PAI-1 levels for each 10 μg/mThe present study showed that both long- and short-term exposures to PM are associated with changes in circulating levels of biomarkers in pregnant women reflecting systemic inflammation and endothelial dysfunction/activation. Our findings support the hypothesis that inflammation and endothelial dysfunction might have a central role in modulating the detrimental effects of air pollution exposure during pregnancy.

Copper complexes with different ligands (ethylenediaminetetraacetic acid, EDTA, ammonium citrate tribasic, TAC, and alanine, ALA) were studied in aqueous solutions and hydrogels with the aim of setting the optimal conditions for copper stain removal from marble by agar gels, with damage minimization. The stoichiometry and stability of copper complexes were monitored by ultraviolet-visible (UV-Vis) spectroscopy and the symmetry of Cu(II) centers in the different gel formulations was studied by electron paramagnetic resonance (EPR) spectroscopy. Cleaning effectiveness in optimized conditions was verified on marble laboratory specimens through color variations and by determining copper on gels by inductively coupled plasma-mass spectrometry (ICP-MS). Two copper complexes with TAC were identified, one having the known stoichiometry 1:1, and the other 1:2, Cu(TAC)2, never observed before. The stability of all the complexes at different pH was observed to increase with pH. At pH 10.0, the gel’s effectiveness in removing copper salts from marble was the highest in the presence of ALA, followed by EDTA, TAC, and pure agar gel. Limited damage to the marble surface was observed when gels with added EDTA and TAC were employed, whereas agar gel with ALA was determined to be the most efficient and safe cleaning material.

Biochar nanoparticles (BC NPs), produced by low temperature pyrolysis (350 °C) of microalgae (Nannochloropsis sp.) and nutshells, are proposed as low-cost and sustainable co-catalysts to promote the photocatalytic activity of TiO2 nanotube (NT) arrays towards the degradation of methylene blue (MB) used as an organic pollutant model molecule. BC NPs (size &lt, 25 nm) were obtained by treating bulk BC (i.e., biomass after pyrolysis) by sonication–centrifugation cycles in a water solution. The filtered BC NPs dispersion was deposited by simple drop-casting on the TiO2 NT support. The BC loading was varied by performing multiple depositions. Photocatalytic experiments under UV light (365 nm) revealed that the decoration with BC NPs significantly improves the TiO2 photoactivity. Such enhancement is mainly influenced by the amount of BC deposited, upon optimizing the BC deposition conditions, the rate of photocatalytic degradation of MB increases approximately three times with respect to bare TiO2, almost irrespective of the nature of the raw material. The greater photocatalytic activity of BC-TiO2 can be attributed to the synergistic combination of reactant/product adsorption and catalytic degradation of the adsorbed organic pollutant, as well as an improved charge carrier separation and electron transfer.

A frontal chromatography-ICP-MS method (FC-ICP-MS) is proposed as an innovative approach for fast elemental speciation analysis: inorganic arsenic speciation was selected as the first case study to prove the feasibility of the technique and to explore its potentialities and limits. The principal benefits of the FC-ICP-MS approach are the short analysis time and the very simple instrumental setup. As(III) and As(V) front separation is performed over a strong anion exchanger at pH 7.5. After the optimization of the instrumental setup and the frontal chromatographic parameters, As(III) and As(V) concentrations up to 240 μg/kg can be determined within 120-140 s using different univariate and multivariate calibration approaches. Best results in terms of accuracy in prediction were obtained using the partial least squares (PLS) calibration achieving limits of detection of 0.18 and 0.21 μg/kg for As(III) and As(V), respectively. This approach was also used to establish the figures of merit of the method. The proved feasibility and good performances (in terms of analysis time and accuracy) of this technique lay the groundwork for future applications of FC-ICP-MS for the speciation of other elements.

We provided the first multi-species study investigating the presence and organotropism of trace elements in three tissues of 12 elasmobranch species. Shark species showed comparable TE loads, although milk sharks and juvenile scalloped hammerhead sharks exhibited the highest Cd and Hg levels, respectively. Fins accumulated higher levels of Pb, Co, and Cr; muscles higher V, As, and Hg; livers higher Se and Cd levels. The organotropism of TEs calls for cautious when choosing a tissue to be sampled since certain tissues, like fin clips, do not provide reliable surrogate for the internal loads of some TEs. Strong correlations between essential and toxic TEs indicated detoxification mechanisms, while the TMF provided evidence for Hg, As and Se biomagnification along the food-web. Considering the difficulties in assessing elasmobranchs contamination from different areas, the proposed multi-species approach represents a valuable way to estimate the species-specific accumulation and transfer of pollutants in sharks.

A laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) based method is proposed for the quantitative determination of the spatial distribution of metal nanoparticles (NPs) supported on planar substrates. The surface is sampled using tailored ablation patterns and the data are used to define three-dimensional functions describing the spatial distribution of NPs. The volume integrals of such interpolated surfaces are calibrated to obtain the mass distribution of Ag NPs by correlation with the total mass of metal as determined by metal extraction and ICP–MS analysis. Once this mass calibration is carried out on a sacrificial sample, quantifications can be performed over multiple samples by a simple micro-destructive LA–ICP–MS analysis without requiring the extraction/dissolution of metal NPs. The proposed approach is here tested using a model sample consisting of a low-density polyethylene (LDPE) disk decorated with silver NPs, achieving high spatial resolution over cm2-sized samples and very high sensitivity. The developed method is accordingly a useful analytical tool for applications requiring both the total mass and the spatial distribution of metal NPs to be determined without damaging the sample surface (e.g., composite functional materials and NPs, decorated catalysts or electrodic materials).

Plastic and microplastic pollution is an environmental and societal concern. The interaction of plastic with organic chemicals in the environment has attracted scientific interest. New evidences have highlighted an unexpectedly high affinity of environmental plastics also for metal ions. The degree and typology of plastic ageing (including from mechanical, UV and biological degradations) appear as a pivotal factor determining such an interaction. These earlier evidences recently opened a new research avenue in the plastic pollution area. This review is the first to organize and critically discuss knowledge developed so far. Results from field and laboratory studies of metal accumulation on plastic are presented and the environmental factors most likely to control such an interaction are discussed. On the light of this knowledge, a generalist conceptual model useful for building hypotheses on the mechanisms at stake and directing future studies was elaborated and presented here. Furthermore, all available data on the thermodynamics of the plastic-metal interaction obtained from laboratory experiments are inventoried and discussed here, highlighting methodological and technical challenges that can potentially affect cross-comparability of data and their relevance for environmental settings. Finally, insights and recommendations on experimental approaches and analytical techniques that can help overtaking current limitations and knowledge gaps are proposed.

Iron speciation in seawater is of the utmost importance as this element plays a central role in the regulation of primary productivity. Here we present the development of a CLE-CSV (Competitive Ligand Equilibration-Cathodic Stripping Voltammetry) procedure for iron speciation in seawater avoiding for the first time the use of the pH buffer (2,3-dihydroxynaphthalene is used as the added ligand, atmospheric oxygen as the catalytic enhancer and a 1 mL volume per sample aliquot). The unbuffered method was setup, validated by using known ligands and finally applied to the analysis of six seawater samples from the Ross Sea (Antarctica). The validation procedure demonstrated that ultratrace levels of ligands may be reliably determined and the application to seawater samples proved that the complex natural ligand pool can be detected with results undistinguishable from the ones obtained by the buffered procedure. The proposed method demonstrated a new principle in trace element speciation analysis by CLE-CSV, namely that the equilibration step may be performed at natural pH, whereas the pH may be set at its optimal value for sensitivity during analysis, thanks to the raise in pH at the electrode/solution interface caused by oxygen reduction. This change in paradigm paves the way to the investigation of iron speciation at natural pH in traditionally difficult samples that show circumneutral or slightly acidic pH values. The relevance of the here proposed approach to existing speciation procedures by CLE-CSV is also discussed.

A fast and cost-effective procedure based on Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) for the selective determination of methylmercury (MeHg) is proposed and validated for fish tissue analysis. Selectivity for MeHg is achieved by simply inserting a strong anion exchange resin to block inorganic mercury as negatively charged chloride species, leaving MeHg unretained. The procedure features a 15 min extraction time followed by a 100 s analysis time achieving a limit of detection of 1.6 μg kg

The investigation of trace element pollution is important for the environmental assessment and management of lacustrine ecosystems, especially when these represent critical freshwater resources in densely populated areas. In this context, this study determined the levels of 15 trace elements in muscles of shad, Alosa agone (Scopoli 1786), a commercialized zooplanktivourous fish, from three primary, but currently still poorly studied, Italian lakes, namely, Lake Como, Iseo, and Garda. Research findings show that shads present similar trace element accumulation patterns among lakes, except for arsenic, which occurs at lower levels in Lake Como. Results provide evidence also for mercury biomagnification in fish, whereas all the other selected trace elements undergo bio-dilution through the same trophic chain. Maximum allowable limits for foodstuff were exceeded for chromium and selenium in shads, whereas mercury levels exceeded the European Environmental Quality Standard biota. These results highlight the need for regular monitoring activities of trace elements in the biota of these lakes.

The use of insoluble bismuth salts, typically BiPO4, is known to be a viable alternative to classical Bi3+ ion electrochemical reduction for the preparation of bismuth film electrodes (BiFE) on screen-printed electrodes. The freshly prepared electrodes are indefinitely stable, and the active bismuth film is simply formed by in situ reduction. Two aspects are still to be investigated, namely the bismuth distribution on the working electrode and the possible residual presence of the counteranion, namely phosphate. High-vacuum techniques such as electron microscopy or spectroscopy, which are commonly employed for this purpose, cannot be safely used: the bismuth surface is well-known to reconstruct and recrystallize under the electron beam in vacuum. Here, we demonstrate the suitability and the effectiveness of laser ablation ICP-MS (LA-ICP-MS, a technique that vaporizes and analyzes the surface material under flowing helium at atmospheric pressure) for the characterization of BiFE. Fast and stable measurements of bismuth and phosphorous distribution are achieved with the advantage of a minimum alteration of the sample surface, avoiding possible interferences. This investigation evidenced how, upon reductive activation, the bismuth film is distributed with a radial symmetry and the phosphate counteranion is completely absent on the working electrode surface.

In this paper, we proposed a high-throughput microwave digestion system based on multi-batch reactors (three quartz test tubes inside commercial PTFE vessels). This original configuration was validated by ICP-MS analysis of several elements in biological certified reference materials (fish tissues and plankton). The proposed system was proved to be free from contamination showing very low LODs. The improved hardware configuration is therefore highly beneficial for the detection of trace elements in microsamples from the marine food web.

Hydrogels based on hyaluronic acid are used to restore volume, hydration, and skin tone, as well as to correct scars, asymmetries or defects of the soft tissue. Hyaluronic acid is often chemically crosslinked with different crosslinking agents in order to improve its mechanical and biological properties. Here we focused on defining the chemical and mechanical characterization of a new hydrogel with specific characteristics: hyaluronic acid polyethylene glycol (PEG)-crosslinked with a high concentration of hyaluronic acid (28 mg/mL), manufactured by MatexLab Spa, via Carlo Urbani 2, ang Via Enrico Fermi, Brindisi, Italy. We made a quantitative and qualitative analysis of the content of sodium hyaluronate in the hydrogel after polymerization and sterilization processes and also evaluated histologically the bio integration of these hydrogels in the cutaneous soft tissues. The results suggest that hyaluronic acid hydrogel PEG-crosslinked have great bio integration, great chemical and mechanical properties, compared with other products available on the market, that are cross-linked with different cross-linking agents. The nontoxicity and nonimmunogenicity of PEG guarantee the lack of allergic and immunological reactions. The PEG-crosslinking technology guarantees a high duration time of the implanted hydrogel because of more resistant physiological degradation.

Soy sauce is a widespread food commodity very common in East and Southeast Asia. It features a complex matrix, including a highly saline matrix (NaCl up to 15%) and a relevant organic component, typically around 15%. Methods for trace element determination in this matrix have been scarcely reported and no procedure has been proposed including Total Reflection X-Ray Fluorescence (TXRF). Aim of the present paper is to setup a TXRF method requiring minimum sample treatment and suitable for process control and risk assessment related to soy sauce consumption. Accordingly, a digestion (HNO3/H2O2) plus dilution (1:5 w/w) procedure was developed, applied to six soy samples from the Chinese market and the results compared to Inductively Coupled Plasma–Mass Spectrometry data. As a result, the procedure was fully validated for the six elements that could be compared: Cu, Fe, Mn, Rb, Sr and Zn. A dilution only procedure was also assessed showing, on average, a −5% bias only. Accordingly, sample digestion yields highly accurate data, whereas a simple 1:5 dilution may be perfectly suited for most purposes. Regarding detection capabilities, the limits of detection are typically below 0.5 mg/kg for both digested + diluted and diluted only samples. The reported procedures are accordingly fit for purpose in quality assurance/quality control procedures and risk assessment related to soy sauce consumption.

A suitable protocol for the collection, extraction, and characterization of a large quantity of a local and current fine particulate matter (PM2.5) was developed, to provide homogeneous PM2.5 amounts for use in in vitro and in vivo toxicological assays rather than a generic and obsolete standard reference material (SRM). PM2.5 samples were collected at an outdoor urban background site in Como, Northern Italy, using a high-volume air sampler (500 L/min) equipped with polytetrafluoroethylene (PTFE)-coated glass fiber filters (eight sampling campaigns of 24–96 h each, from February to April 2019). PM2.5 was extracted from the filters by sequential sonication steps and the final pooled extract was filtered to remove the glass fibers released during extraction. Several PM2.5 aliquots (n = 55) were then prepared from the PM2.5 dry residue for i) a chemical characterization of the elements, inorganic ions, and the carbonaceous fraction and ii) in vivo and in vitro studies. The proposed protocol allowed a large amount of ambient PM2.5 (>300 mg) to be collected within a reasonably short time. An average extraction efficiency of 75% was achieved, and the chemical analyses conducted on a set of PM2.5-replicates revealed a satisfactory level of precision, ranging from 3% (anions and OC) to 10% (trace metals and EC), thereby confirming the possibility of obtaining aliquots with homogeneous mass and composition. Finally, the emerging differences with the SRM 1648a elemental composition suggest the importance of location- and time-specific particulate testing, which is truly representative of the actual exposure scenario for specific populations.

BACKGROUND: Hyaluronic acid (HA) based hydrogels for esthetic applications found widespread use. HA should be crosslinked for this application to achieve the correct viscoelastic properties and avoid fast degradation by the hyaluronidase enzyme naturally present in the skin: these properties are controlled by the amount of crosslinker and the fraction that is effectively crosslinked (i.e. that binds two HA chains). AIM: Crosslinking by polyethylene glycol diglycidyl ether (PEGDE) has been more recently introduced and showed attractive features in terms of viscoelastic properties and reduced biodegradation. Aim of this paper is to define a method for the determination of the crosslinking properties of these recently introduced fillers, method that is lacking at the moment. MATERIAL AND METHOD: The percentage of crosslinker and the fraction that is effectively crosslinked were determined by proton Nuclear Magnetic Resonance (1H NMR) and by 13C NMR, respectively. The filler were preliminarily washed with acetonitrile to remove residual PEG and then digested by hyaluronidase to obtain a sample that can be analysed by NMR. RESULTS: The crosslinking parameters were determined in four samples of NEAUVIA PEG-crosslinked dermal fillers (produced by MatexLab S.p.A., Italy). The percentage of crosslinker was between 2.8% and 6.2% of HA, whereas the effective crosslinker ratios were between 0.07 and 0.16 (ratio between the moles of effectively crosslinked PEG and total moles of PEG). Moreover, a digestion procedure alternative to enzymatic digestion, based on acidic hydrolysis, was successfully tested for the determination of crosslinker percentage. CONCLUSIONS: The proposed method successfully determined the two crosslinking parameters in PEG-crosslinked dermal fillers. The estimated percentage of crosslinker is similar to previously reported data for other crosslinkers, whereas the effective crosslinker ratio is lower for PEG crosslinked hydrogels. BACKGROUND: Hyaluronic acid (HA) based hydrogels for esthetic applications found widespread use. HA should be crosslinked for this application to achieve the correct viscoelastic properties and avoid fast degradation by the hyaluronidase enzyme naturally present in the skin: these properties are controlled by the amount of crosslinker and the fraction that is effectively crosslinked (i.e. that binds two HA chains). AIM: Crosslinking by polyethylene glycol diglycidyl ether (PEGDE) has been more recently introduced and showed attractive features in terms of viscoelastic properties and reduced biodegradation. Aim of this paper is to define a method for the determination of the crosslinking properties of these recently introduced fillers, method that is lacking at the moment. MATERIAL AND METHOD: The percentage of crosslinker and the fraction that is effectively crosslinked were determined by proton Nuclear Magnetic Resonance (1H NMR) and by 13C NMR, respectively. The filler were preliminarily washed with acetonitrile to remove residual PEG and then digested by hyaluronidase to obtain a sample that can be analysed by NMR. RESULTS: The crosslinking parameters were determined in four samples of NEAUVIA PEG-crosslinked dermal fillers (produced by MatexLab S.p.A., Italy). The percentage of crosslinker was between 2.8% and 6.2% of HA, whereas the effective crosslinker ratios were between 0.07 and 0.16 (ratio between the moles of effectively crosslinked PEG and total moles of PEG). Moreover, a digestion procedure alternative to enzymatic digestion, based on acidic hydrolysis, was successfully tested for the determination of crosslinker percentage. CONCLUSIONS: The proposed method successfully determined the two crosslinking parameters in PEG-crosslinked dermal fillers. The estimated percentage of crosslinker is similar to previously reported data for other crosslinkers, whereas the effective crosslinker ratio is lower for PEG crosslinked hydrogels.

A comprehensive approach to the characterization and setup of metal determination by adsorptive stripping voltammetry with catalytic enhancement (CAdSV) is presented. The focus is on the understanding of the chemical features of these procedures to demonstrate which parameters can influence the analytical performances: the CAdSV method for the determination of iron at trace level using 2,3-dihydroxynaphthalene (DHN) is taken as case study. First, the ligand degradation was investigated by 1H NMR spectroscopy highlighting a significant degradation at alkaline pH of around 33% in 12 h. The use of degraded DHN had a detrimental effect on the analytical sensitivity, highlighting the need to frequently prepare the ligand. The thermodynamics of ligand and complex adsorption onto the working electrode (hanging mercury drop electrode, HMDE) was subsequently studied: both showed a strong adsorption onto the mercury surface (βDHN = 2.5·103 ± 5·102 L mol−1; βFe-DHN = 5.5·105 ± 8·104 L mol−1), but no competition for the mercury surface between the ligand and the complex was evident as determined by the multicomponent Langmuir isotherm. The mechanism of the electrode reaction was also investigated with and without the catalytic enhancement of the signal caused by air oxygen. The reduction of the complex Fe-DHN in purged solution showed α = 0.57 and k0 = 79 cm s−1, highlighting a quasireversible mechanism. The apparent catalytic constant (k'cat) was 168 s−1 for 1 mL sample volume: the simultaneous study of the kinetic and catalytic constant showed that the current signal was mostly influenced by the kinetic of the reaction.

An analytical method derived from the coupling of frontal chromatography (FC) with Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) is proposed for the fast determination of Cr(VI) ultra-traces. The insertion of a short, homemade column filled with a strong cationic exchange resin in the flow-path of a commercial ICP-MS allows on-line trapping of cationic Cr(III) and elution of anionic Cr(VI). As a result, only the Cr(VI) front reaches the detector. This separation mechanism enables the highly selective quantification of Cr(VI) ultra-traces (LOD = 0.026 µg/kg - defined as 3 s of 10 replicated measurements of a 0.050 µg/kg solution) over a wide linearity range (tested up to 1024 µg/kg), even in the presence of Cr(III) concentration as high as 50 mg/kg. Key advantages of the proposed method are the extremely short analysis time (one minute), together with the simplicity and cost-effectiveness of the modifications applied over a commercial ICP-MS instrumental configuration. No time- or chemical-consuming pretreatments are needed: it is only necessary to acidify the sample prior Cr(VI) determination, as normally performed for common ICP-MS analysis. The applicability of the method was demonstrated over mineral water samples and toy migration solutions.

The chemical analysis of tree rings has attracted the interest of researchers in the past five decades in view of the possibility of exploiting this biological indicator as a widely available, high-resolution environmental archive. Information regarding the surrounding environment can be derived either by directly measuring environmental variables (nutrient availability, presence of pollutants, etc.) or by exploiting proxies (e.g. paleoclimatic and paleoenvironmental reconstructions). This review systematically covers the topic and provides a critical view on the reliability of dendrochemical information. First, we introduce the determinable chemical species, such as major elements, trace metals, isotopic ratios, and organic compounds, together with a brief description of their uptake mechanisms and functions in trees. Subsequently, we present the possibilities offered by analytical techniques in the field of tree ring analysis, focusing on direct methods and recent developments. The latter strongly improved the details of the accessible information, enabling the investigation of complex phenomena associated with plant life and encouraging the direct analysis of new analytes, particularly minor organic compounds. With regard to their applications, dendrochemical proxies have been used to trace several processes, such as environmental contamination, paleoclimate reconstruction, global environmental changes, tree physiology, extreme events, ecological trends, and dendroprovenance. Several case studies are discussed for each proposed application, with special emphasis on the reliability of tracing each process. Starting from the reviewed literature data, the second part of the paper is devoted to the critical assessment of the reliability of tree ring proxies. We provide an overview of the current knowledge, discuss the limitations of the inferences that may be drawn from the dendrochemical data, and provide recommendations for the best practices to be used for their validation. Finally, we present the future perspectives related to the advancements in analytical instrumentation and further extension of application fields.

A method with negligible blank values for the determination of total iron at the ultratrace level in seawater has been optimized and validated exploring for the first time the performance and limitations of Adsorptive Cathodic Stripping Voltammetry (AdCSV) in non-buffered solutions. The method is based on the CSV determination of the Fe-dihydroxynaphthalene (DHN) complex using atmospheric oxygen to catalytically enhance the signal via hydrogen peroxide formation at the electrode/solution interface. The accumulation of hydroxyl ions, the by-product of the hydrogen peroxide formation, increased the pH in the diffusion layer in the absence of buffer bringing it to 9, the optimum for the analytical performance of the method. Voltammograms in UV digested seawater showed no stability or reproducibility drawbacks. The negligible, lower than 5pM, blank level, is due to the simplicity of the procedure requiring no sample manipulation and a maximum of three reagents only, necessarily the ligand DHN and a base only for those samples previously acidified to raise the pH to circumneutral values (here HCl and NH3 according to common trace metals protocols). These reagents do not require cleaning before use, further simplifying the overall procedure. Analysis of seawater previously acidified at pH ~1.5 with HCl and neutralized with ammonia showed interferences due to the buffering properties of the NH3/NH4Cl couple and the transient formation of a volatile electroactive interference that can be easily removed by simply allowing a set time before analysis. In general, the proposed method features several advantages, including high sample throughput, an excellent limit of detection at 12pM, minimum sample handling (no preconcentration or change of matrix is required), cost effectiveness and mainly a negligible blank. The method was successfully validated using open ocean consensus samples (SAFe D2 and S).

The presence of elemental impurities in fuels is a key topic with important consequences: they may both adversely affect the performances of engines and contribute to the contamination of the environment, primarily air, but on the long term also waters and soils. Accordingly, the determination of trace elements in fuels is of the utmost importance in several fields, ranging from quality control to regulatory issues (e.g. control of emissions). Traditionally, atomic spectrometric techniques have been employed to this aim: these techniques typically require a pretreatment step involving either sulfate ashing, microwave digestion or dilution in solvents. Here we propose a fast, direct and sensitive method for the quantification of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Pb at trace level in light and middle distillates, namely gasoline, racing and jet fuel, by Total Reflection X-Ray Fluorescence (TXRF). A simple sample treatment procedure, based on on-site enrichment, allowed to achieve limits of detection below 1 ng/g. The quantification method by internal standard was assessed and validated by recovery tests: its optimization and limits will be presented and discussed.

Within Djibouti (Gulf of Aden), the scalloped hammerhead shark (Sphyrna lewini) and milk shark (Rhizoprionodon acutus) are important components of the artisanal fishery and they are caught to be exported or sold for local consumption. However, little scientific information exists on the contamination load of these species in this area of the world. With global populations of elasmobranchs in decline, understanding the extent of contaminant exposure is critical to future conservation as well as to assess the health risks for consumers of these species. The contaminants analyzed in this study comprised PCB, DDT and trace elements in livers, muscles and fins of both hammerhead sharks and milk sharks. The overall organochlorine compounds (OCs) and trace elements concentrations were similar among the two sharks' species and the pattern of PCB and DDT tissue distribution showed the highest burdens in livers compared with muscles and fins. However, the different accumulation profiles of OCs among shark species suggest species-specific accumulation of these contaminants. The p,p'DDE/∑DDT ratios were equal or slightly higher than the critic value of 0.6, suggesting possible recent inputs of technical DDT in the area. Concentration of trace elements from this study were generally comparable to those found in sharks from other areas of the world and, highlight the wide variation in metal concentrations between species, individuals and tissues. As far as Hg is concerned, scalloped hammerhead sharks showed higher accumulation in muscles compared with milk sharks. Both species showed elevated concentration of Se, which might be related to high Hg levels since Se inhibits Hg toxicity. The potential cancer risk for PCB, Cd, Ni, Cr and As fell within the range of 10-6-10-4, suggesting some concerns for the overall contamination levels in both species. Indeed, consuming of fish involves a mixture of all analyzed elements, and therefore, some potential risk might arise from regularly consuming these species.

Decentralization of on-site and in-site trace metal analysis has been a key topic over the last 30 years, owing to the increasing need for environmental protection as well as industrial and health-based field applications. In trace (and ultratrace) metal analysis, electrochemical stripping analysis with mercury (or bismuth) screen-printed film electrodes has shown a fast growth in popularity thanks to the good limits of detection, the ease of application in the field, and the low cost. Moreover, the availability of new wall-jet flow cells has opened the opportunity for their use in in situ industrial monitoring. The analytical figures of merit in stripping voltammetry with screen-printed electrodes (SPEs) under decentralized conditions and/or with sensor arrays are heavily affected by some analytical factors, primarily the presence of a pseudo-reference electrode, the efficiency of mass transport during the preconcentration step, and the need for external calibration. A careful model investigation of the analytical parameters for an efficient use of SPEs in decentralized conditions has been undertaken and discussed. Different instrumental approaches were investigated, comparing optimized batch conditions and flow cell operation under either continuous flow or stopped-flow sample injection. The stripping efficiency under wall-jet flow conditions was found to be high and comparable to that in batch conditions, leading to sub-ppb (&mu, g/L) limit of detection (LOD) figures. Finally, external calibration in stripping voltammetry was studied as a viable alternative to conventional standard addition quantitation. Results showed, indeed, that external calibration was demonstrated to be reliable for quantitation of Pb and Cd in real water samples.

Neauvia Intense is biocompatible, injectable hyaluronic acid (HA) filler PEG cross-linked for facial soft-tissue augmentation that provides volume to tissues. The aim of the present study is to evaluate the sensitivity of Neauvia Intense in hyaluronidase from bovine testes in a time-course analysis. The test is based on the colourimetric determination of the N-acetyl – D - glucosamine (NAG) released by the hyaluronidase in standardised conditions. The in vitro conditions involve the treatment of Neauvia Intense with a known concentration of the enzyme (6080U/ml). The NAG content was determined at different times to assess the kinetics of the degradation (1h, 3h, 6h, 24h, 48h, 72h, 120h, and 168h); the Ehrlich’s reagent was used for the colourimetric quantification, by the method described by Reissing and colleagues. The intensity of the violet colour developed after the chemical reaction was proportional to the NAG present in each sample. A microplate reader at 585 nm read the absorbance. The amount of NAG released by the product was proportional to the time of incubation with bovine hyaluronidase, reaching a plateau after 168 hours.

OBJECTIVE: Neauvia Stimulate is biocompatible, injectable hyaluronic acid (HA) filler (26 mg/ml) PEG crosslinked with 1% of calcium hydroxyapatite (CaHA) for facial soft-tissue augmentation that provides volume to tissues, followed by process of neocollagenesis for improving skin quality. AIM: The aim of the present study is to evaluate the biosafety of the product (Lot. 160517-26-1/2 PEG) on human keratinocytes cultured in vitro. MATERIAL AND METHODS: The experimental model proposed, despite being an in vitro system, allows the derivation of useful information to predict the possible activity of the product in further in vivo application. Human keratinocytes (HaCaT cells) were treated with the product for 24h at increasing concentrations of product respect to control (untreated cells). RESULTS: The biosafety of the product to be tested has been evaluated performing different methods: MTT test, NRU test, Kenacid Blue assay. Moreover, any possible effect on the structure, morphology, and viability of cells has been evaluated. CONCLUSION: In conclusion, the results obtained by the different methods show that the product Neauvia Stimulate® does not cause any cytotoxic effect and does not affect the correct structure and morphology of cells cultures. OBJECTIVE: Neauvia Stimulate is biocompatible, injectable hyaluronic acid (HA) filler (26 mg/ml) PEG crosslinked with 1% of calcium hydroxyapatite (CaHA) for facial soft-tissue augmentation that provides volume to tissues, followed by process of neocollagenesis for improving skin quality. AIM: The aim of the present study is to evaluate the biosafety of the product (Lot. 160517-26-1/2 PEG) on human keratinocytes cultured in vitro. MATERIAL AND METHODS: The experimental model proposed, despite being an in vitro system, allows the derivation of useful information to predict the possible activity of the product in further in vivo application. Human keratinocytes (HaCaT cells) were treated with the product for 24h at increasing concentrations of product respect to control (untreated cells). RESULTS: The biosafety of the product to be tested has been evaluated performing different methods: MTT test, NRU test, Kenacid Blue assay. Moreover, any possible effect on the structure, morphology, and viability of cells has been evaluated. CONCLUSION: In conclusion, the results obtained by the different methods show that the product Neauvia Stimulate® does not cause any cytotoxic effect and does not affect the correct structure and morphology of cells cultures.

Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS) is a powerful method to determine the elemental composition of solid-state samples as it combines the high sensitivity and isotope selectivity of ICP-MS detection and the simplicity of laser ablation sampling. This technique enables rapid multiple sampling of the analysed material, such as needed for mapping or in-depth profiling applications. However, the duration of these measurements is practically restricted by the time taken for the particle to be transported from the sampling point to the ICP torch. The ablation cell, i.e. the sample holder, should combine high removal rate, high efficiency (i.e. complete transport of the ablated material) and reduced memory effects. These goals may be achieved by carefully designing the geometry of the cell and its gas flow patterns. A new cell design which enables a homogeneous wahout time of around 210 ms from a cylindrical chamber with 70 mm diameter is introduced in this paper. Washout time was determined as the time for the transient signal of 238U from a NIST610 glass standard to fall to 10% of its peak value. This result is achieved by combining a diffused, cylindrical flow pattern with an extraction tube coaxial with the laser beam and fixed to the laser assembly which enables the sampling point to be constantly positioned on the ablation spot. The lower part of the cell is mounted on the x,y stage for sample movement: the cell sealing is warranted by a viscous film junction between the lower and upper cell parts. Optimisation and performances of the apparatus are discussed in detail and performances are compared to existing designs.

Eight spirituous samples were analyzed for trace metal content with Horizon Total Reflection X-Ray Fluorescence (TXRF) Spectrometer. The expected single metal amount is at the ng/g level in a mixed aqueous/organic matrix, thus requiring a sample preparation method capable of achieving suitable limits of detection. On-site enrichment and Atmospheric Pressure-Vapor Phase Decomposition allowed to detect Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr and Pb with detection limits ranging from 0.1 ng/g to 4.6 ng/g. These results highlight how the synergy between instrument and sample preparation strategy may foster the use of TXRF as a fast and reliable technique for the determination of trace elements in spirituous samples, either for quality control or risk assessment purposes.

The recent growing interest in peracetic acid (PAA) as disinfectant for wastewater treatment demands reliable and readily-available methods for its measurement. In detail, the monitoring of PAA in wastewater treatment plants requires a simple, accurate, rapid and inexpensive measurement procedure. In the present work, a method for analyzing low concentrations of PAA, adapted from the US EPA colorimetric method for total chlorine, is assessed. This method employs N,N-diethyl-p-phenylelnediamine (DPD) in the presence of an excess of iodide in a phosphate buffer system. Pink colored species are produced proportionally to the concentration of PAA in the sample. Considering that PAA is available commercially as an equilibrium solution of PAA and hydrogen peroxide (H2O2), a measurement method for H2O2 is also investigated. This method, as the one for the determination of PAA, is also based on the oxidation of iodide to iodine, with the difference that ammonium molybdate Mo(VI) is added to catalyze the oxidation reaction between H2O2 and iodide, quantifying the total peroxides (PAA+ H2O2). The two methods are suitable for concentration ranges from about 0.1–1.65 mg L−1 and from about 0.3–3.3 mg L−1, respectively for PAA and H2O2. Moreover, the work elucidates some relevant aspects related to the operational conditions, kinetics and the possible interference of H2O2 on PAA measurement.

A new method based on adsorptive cathodic stripping voltammetry with catalytic enhancement for the determination of total dissolved iron in seawater is reported. It was demonstrated that iron detection at the ultratrace level (0.1 nM) may be achieved in small samples (500 μL) with high sensitivity, no need for purging, no added oxidant, and a limit of detection of 5 pM. The proposed method is based on the adsorption of the complex Fe/2,3-dihydroxynaphthalene (DHN) exploiting the catalytic effect of atmospheric oxygen. As opposite to the original method (Obata, H.; van den Berg, C. M. Anal. Chem. 2001, 73, 2522-2528), atmospheric oxygen dissolved in solution replaced bromate ions in the oxidation of the iron complex: removing bromate reduces the blank level and avoids the use of a carcinogenic species. Moreover, the new method is based on a recently introduced hardware that enables the determinations to be performed in 500 μL samples. The analyses were carried out on buffered samples (pH 8.15, HEPPS 0.01 M), 10 μM DHN and iron quantified by the standard addition method. The sensitivity is 49 nA nM(-1) min(-1) with 30 s deposition time and the LOD is equal to 5 pM. As a result, the whole procedure for the quantification of iron in one sample requires around 7.5 min. The new method was validated via analysis on two reference samples (SAFe S and SAFe D2) with low iron content collected in the North Pacific Ocean.

Summary Developments in iron detection and speciation in natural waters by electrochemical methods are reviewed considering latest, post 2010, evolutions. Voltammetric and potentiometric methods have been employed to detect iron and iron species in natural waters, potentiometric methods being devoted to redox speciation only. Regarding iron detection by voltammetry on the mercury electrode, several improvements have been introduced since 2014, leading to a very low detection limit (LOD, 5 pM), reduced analysis time, elimination of the UV pretreatment and a 20-fold reduction in sample size. Chemically modified, mercury free, electrodes have started to be introduced. Among bulk electrodes, bismuth and bismuth alloy offer the best performances in term of detection limit (0.2 nM). Gold or gold nanoparticle electrodes modified with self-assembled monolayers of different thiols are the most promising among chemically modified electrodes: thiols bear an iron complexing moiety that efficiently preconcentrate iron onto the electrode surface with a claimed LOD of 30 pM. Regarding iron speciation analysis, no substantial advances have been recently achieved. Several ionophores were synthesised and tested in potentiometric electrodes for iron redox speciation (for the detection of both Fe(III) and Fe(II) species), but their use is limited to acidic solutions due to sensitivity limitations. Finally, the voltammetric detection of iron complexation by competitive ligand—cathodic stripping voltammetry has made limited methodological progresses since its introduction in 1994, although improved data treatment procedures have been conveniently implemented.

Voltammetric techniques have emerged as powerful methods for the determination and speciation of trace and ultratrace elements without any preconcentration in several research fields. Nevertheless, large sample volumes are typically required (10 mL), which strongly limits their application and/or the precision of the results. In this work, we report a 20-fold reduction in sample size for trace and ultratrace elemental determination and speciation by conventional voltammetric instrumentation, introducing the lowest amount of sample (0.5 mL) in which ultratrace detection has been performed up to now. This goal was achieved by a careful design of a new sample holder. Reliable, validated results were obtained for the determination of trace/ultratrace elements in rainwater (Cd, Co, Cu, Ni, Pb) and seawater (Cu). Moreover, copper speciation in seawater samples was consistently determined by competitive ligand equilibration-cathodic stripping voltammetry (CLE-CSV). The proposed apparatus showed several advantages: (1) 20-fold reduction in sample volume (the sample size is lowered from 120 to 6 mL for the CLE-CSV procedure); (2) decrease in analysis time due to the reduction in purging time up to 2.5 fold; (3) 20-fold drop in reagent consumption. Moreover, the analytical performances were not affected: similar detection capabilities, precision and accuracy were obtained. Application to sample of limited availability (e.g. porewaters, snow, rainwater, open ocean water, biological samples) and to the description of high resolution temporal trends may be easily foreseen.