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A certified reference material. NIMD-01, was developed for the analysis of mercury speciation in human hair. We collected the hair of Vietnamese males from a barbershop in Hanoi in 2016 and prepared 1200 bottles containing 3 g of sieved and blended hair powder. The certified value was given on a dry-mass basis, with the moisture content obtained by drying at 85°C for 4 h. Certified values with the expanded uncertainties (coverage factor, k = 2) were as follows: methylmercury, 0.634 ±0.071 mg kg -1 as mercury; total mercury. 0.794 ± 0.050 mg kg -1; copper, 12.8 ± 1.4 mgkg -1; /inc. 234 ± 29 mg kg -1; selenium, 1.52 ± 0.29 mg kg -1. An indicative arsenic concentration of 0.17 ± 0.03 mg kg 1 was measured. Extended uncertainties were estimated by sample homogeneity, long-and short-term stabilities, and a characterization from measurements made by collaborating laboratories.

Monitoring patients' metal ion blood concentrations can be useful in cases of problematic metal on metal hip implants. Our objective was to evaluate the reproducibility of metal ion level values measured by two different laboratories. Whole blood samples were collected in 46 patients with metal on metal hip arthroplasty. For each patients, two whole blood samples were collected and analyzed by two laboratories. Laboratory 1 had higher results than laboratory 2. There was a clinically significant absolute difference between the two laboratories, above the predetermined threshold, 35% of Cr samples and 38% of Co samples. All laboratories do not use the same technologies for their measurements. Therefore, decision to revise a metal on metal hip arthroplasty should rely on metal ion trends and have to be done in the same laboratory.

We review the state-of-the-art application of nanoparticles (NPs) in electrochemical analysis of environmental pollutants. We summarize methods for preparing NPs and modifying electrode surfaces with NPs. We describe several examples of applications in environmental electrochemical sensors and performance in terms of sensitivity and selectivity for both metal and metal-oxide NPs. We present recent trends in the beneficial use of NPs in constructing electrochemical sensors for environmental monitoring and discuss future challenges. NPs have promising potential to increase competitiveness of electrochemical sensors in environmental monitoring, though research has focused mainly on development of methodology for fabricating new sensors, and the number of studies for optimizing the performance of sensors and the applicability to real samples is still limited.

This study systematically examines the effect of four common polymers on the size, surface chemistry, colloidal stability, and sedimentation behaviour of nanoparticles of zero valent iron (NZVI). The mean diameters of NZVI ranged from 5 to 189 nm, depending on the synthesis conditions. The influence of the pre- or post-grafting of the polymers on the above parameters was also investigated. The four polymers are carboxymethyl cellulose (CMC), poly(styrenesulfonate) (PSS), poly(acrylic acid) (PAA) and polyacrylamide (PAM). The molecular weight of these polymers range over three orders of magnitude, from 1.8 × 103 to 5000 × 103 g mol−1 and they are all negatively charged with the exception of the non-ionic PAM. All NZVI samples were synthesized by sodium borohydride reduction of ferrous sulfate solutions. For pre-grafting, the NZVI was synthesized in the presence of the different polymers and identical synthesis conditions were maintained which allowed for an unbiased and direct comparison of the characteristics of the different particles. ATR-FTIR analyses revealed that both pre- and post-grafted polymers were bound to the iron nanoparticle surface with polar bonds between carboxylate groups of CMC and PAA, sulfonate groups of PSS, and with hydrogen bonds with the amine groups of the non-ionic PAM. TEM images and nanoparticle tracking analysis revealed that iron nanoparticles synthesised in the presence of the polymers were larger in diameter, with TEM mean diameters ranging from 84.5 to 189 nm, than the bare-NZVI (59.1 nm), when synthesized with the same initial Fe2+ concentration. Altering the CMC or Fe2+ concentration during synthesis allowed synthesis of relatively monodisperse, colloidally stabilized CMC-NZVI with defined average diameters ranging from 5 nm to 129 nm. XPS studies indicated that all pre-grafted polymer-stabilized NZVI had a polymer coating covering a core–shell structure with a shell of iron oxide–hydroxides and a core of Fe0. Pre-grafted CMC was found to be the most efficient in colloidally stabilizing NZVI. Sedimentation tests demonstrated that after 60 min pre-grafted CMC-NZVI were slightly more stable than pre-grafted PAA-NZVI, but at least two-times more stable than pre-grafted PSS- or PAM-NZVI and 13 times more stable than bare-NZVI. The colloidal stability of all post-grafted NZVI was lower than the corresponding pre-grafted particles by 1.3 to 6 times, with the exception of PSS. The nature of polymer–Fe interactions were further explored by ATR-FTIR spectra of pre- and post-grafted particles. These results highlight the relevance of the extent and the nature of the polymer–Fe interactions during synthesis of polymer-stabilized NZVI.

We report herein the synthesis of a new hybrid material, PdNPs@CNCs consisting of monodisperse Pd nanoparticles (PdNPs) evenly deposited onto colloidal cellulose nanocrystallites (CNCs). This material proved an active catalyst for the hydrogenation reaction of phenol to cyclohexanone in water as a solvent, at room temperature, under 4 bar of dihydrogen. Moreover, the catalyst perfomed well in the Heck coupling of styrene and iodobenzene in a hydro-organic mixture. CNCs constitute a highly crystalline, ordered and yet accessible green material easily obtained from wood pulp. This work demonstrates the possibility of using colloidal CNCs as an efficient support for catalysis.

A mathematical model of the electrocatalytic hydrogenation of phenol on a Pd/Al 2 O 3 (10%, w/w) catalyst is developed and presented from the chemical kinetic to the fluid mechanical point of view in a laboratory scale cell. The model includes the heterogenous electrochemical steps at the microscopic scale, integrated in a full transient, three-dimensional representation of the fluid mechanics and species concentration in the electrochemical cell. In this reactor, the catalytic particles are dispersed and recirculated in the solution. The brief contact of the powder with a porous reticulated vitreous carbon is sufficient to obtain adsorbed hydrogen on the nanoaggregates who contains the phenol adsorbed. The isotherm of Langmuir and the pseudo-second-order model, based on assumption of second-order mechanism are developed. The aim of this work is to understand and validate the pseudo-second-order adsorption model when used with hydrogen adsorption isotherm, and to develop a full model of the electrochemical cell. The proposed model could be used to improve the design of industrial scale reactors. The model is validated using experimental results from [A. Bannari, C. Cirtiu, F. Kerdouss, P. Proulx, H. Menard, Chem. Eng. Process. 45 (2006) 471].

The electrocatalytic hydrogenation (ECH) of octyl aldehyde (octanal) to octyl alcohol (octan-1-ol) was investigated using commercial Pd/alumina catalysts in aqueous ethanol. The influence of different parameters, such as catalyst support, current intensity, polarity of solvent, supporting electrolyte, and octanal concentration, on the electrocatalytic hydrogenation of octanal was studied.Key words: octanal, octan-1-ol, Pd/alumina catalyst, electrocatalytic hydrogenation.

Catalytic and electrocatalytic hydrogenation of benzophenone was performed in aqueous ethanol onto 10% (w/w) Pd–alumina supported catalyst and finely divided Pd catalyst. Efficiency of catalytic and electrocatalytic hydrogenation of the studied ketone is discussed here as a comparative study.

Electrocatalytic reaction was examined as an alternative method for the catalytic hydrogenation of cyclohexanone over Pd catalysts. The behavior of Pd/alumina catalyst and finely divided Pd catalyst in the electrocatalytic and catalytic hydrogenation of cyclohexanone in aqueous solution were investigated as a comparative study. The role of the pH of the solution was studied both in electrocatalytic and catalytic hydrogenation over Pd/alumina catalyst using acetic acid as a supporting electrolyte. High current yields were obtained for the electrocatalytic process, whereas, as expected from the literature, the catalytic hydrogenation was inefficient.

Biomonitoring for manganese (Mn) exposure is important due to its potential to cause adverse health effects. In this study, we investigate how different sample preparation methods (simple dilution, digestion, volumetric, gravimetric), calibration protocols (aqueous, blood-based, standard additions), and instrumental techniques affect Mn method bias and analytical imprecision. The techniques used included graphite furnace atomic absorption spectrometry (GFAAS), dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS), and sector field (SF-) ICP-MS. We analyzed NIST SRM 1643e Trace Elements in Water and SRM 1598a Inorganic Constituents in Animal Serum (both certified for Mn), and SRM 955c Toxic Metals in Caprine Blood – Level 1 (not certified for Mn). Various matrix effects in ICP-MS produced inaccurate results for SRM 1643e and discrepant results for SRM 955c. In the absence of a certified value for Mn in SRM 955c, we assigned a “consensus” value by combining data from the New York State Department of Health (NYS), the Centers for Disease Control and Prevention (CDC) and the Centre de toxicologie du Québec (CTQ). With this interlaboratory approach, we established an “all-lab” consensus value of 16.3 ± 0.8 μg L−1 based on data from DRC-ICP-MS with simple dilution sample preparation and blood-based calibration. We also assigned an “all-method” consensus value of 16.3 ± 0.9 μg L−1 based on GFAAS and SF-ICP-MS data from the NYS lab and the DRC-ICP-MS all-lab consensus value. Although the expanded uncertainty (U) calculated for the consensus values may not fully account for all sources of uncertainty, it does show the relative variation that might be expected from one study to the next for the determination of Mn in blood.

Cellulose nanocrystals (CNCs), derived from cellulose, provide us with an opportunity to devise more sustainable solutions to current technological challenges. Enantioselective catalysis, especially heterogeneous, is the preferred method for the synthesis of pure chiral molecules in the fine chemical industries. Cellulose has been long sought as a chiral inducer in enantioselective catalysis. We report herein an unprecedentedly high enantiomeric excess (ee) for Pd patches deposited onto CNCs used as catalysts for the hydrogenation of prochiral ketones in water at room temperature and 4 bar H2. Our system, where CNCs acted as support and sole chiral source, achieved an ee of 65% with 100% conversions. Cryo-electron microscopy, high-resolution transmission electron microscopy, and tomography were used for the first time to study the 3D structure of a metal functionalized CNC hybrid. It established the presence of sub-nanometer-thick Pd patches at the surface of CNCs and provided insight into the chiral induction mechanism.

In order to study the improvement in reaction efficiency associated with the improved flow characteristics over static or quasi static cells, a dynamic electrochemical reactor is designed and tested. Experimental results are compared to a computational fluid dynamics (CFD) model of the cell, based only on turbulence characteristics. We intend to identify the optimal geometrical configuration, using CFD to determine how the electrodes, inlet and outlet tubes should be positionned. It is found that the overall reaction efficiency of the cell correlates almost perfectly with the volumetric turbulence intensity. The incidence angle (IA) formed by the inlet and the position of the electrodes governs the overall reaction rate.

The electrocatalytic hydrogenation (ECH) of phenol has been studied using palladium supported on gamma-alumina (10% Pd-Al2O3) catalysts. The catalyst powders were suspended in aqueous supporting electrolyte solutions containing methanol and short-chain aliphatic acids (acetic acid, propionic acid, or butyric acid) and were dynamically circulated through a reticulated vitreous carbon cathode. The efficiency of the hydrogenation process was measured as a function of the total electrolytic charge and was compared for different types of supporting electrolyte and for various solvent compositions. Our results show that these experimental parameters strongly affect the overall ECH efficiency of phenol. The ECH efficiency and yields vary inversely with the quantity of methanol present in the electrolytic solutions, whereas the presence of aliphatic carboxylic acids increased the ECH efficiency in proportion to the chain length of the specific acids employed. In all cases, ECH efficiency was directly correlated with the adsorption properties of phenol onto the Pd-alumina catalyst in the studied electrolyte solution, as measured independently using dynamic adsorption isotherms. It is shown that the alumina surface binds the aliphatic acids via the carboxylate terminations and transforms the catalyst into an organically functionalized material. Temperature-programmed mass spectrometry analysis and diffuse-reflectance infrared spectroscopy measurements confirm that the organic acids are stably bound to the alumina surface below 200 degrees C, with coverages that are independent of the acid chain length. These reproducibly functionalized alumina surfaces control the adsorption/desorption equilibrium of the target phenol molecules and allow us to prepare new electrocatalytic materials to enhance the efficiency of the ECH process. The in situ grafting of specific aliphatic acids on general purpose Pd-alumina catalysts offers a new and flexible mechanism to control the ECH process to enhance the selectivity, efficiency, and yields according to the properties of the specific target molecule.

The catalyst shows selectivity towards the less activated double bonds and tolerates the presence of air and water.

We report for the first time the use of iron-iron oxide core–shell nanoparticles for the hydrogenation of olefins and alkynes under mild conditions in ethanol and in an aqueous medium. This catalyst proves robust towards the presence of oxidants, such as oxygen and water, is magnetically recoverable and shows selectivity towards the less activated double bonds.

A robust, safe and magnetically recoverable Fe3O4 nanoparticle catalyzed three-component coupling of aldehyde, alkyne, and amine (A3-coupling) was developed. A diverse range of propargylamines were obtained in moderate to high yield under mild conditions in air. The separation and reuse of the magnetic Fe3O4 nanoparticles were very simple, effective and economical.

A robust, safe and magnetically recoverable Fe3O4 nanoparticle catalyzed three-component coupling of aldehyde, alkyne, and amine (A3-coupling) was developed. A diverse range of propargylamines were obtained in moderate to high yield under mild conditions in air. The separation and reuse of the magnetic Fe3O4 nanoparticles were very simple, effective and economical.

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