Critical study of the speciation of aluminum in biological fluids by size-exclusion chromatography and electrothermal atomic absorption spectrometry

Pooled serum and the serum of a healthy volunteer were spiked with aluminum and aluminum species were separated on Bio-gel columns. With the P10 column, less than 40% of the aluminum was eluted with the high-molecular-weight (m.w.>20 00) fraction; the total aluminum concentration was 600 μg l^?1. Tw lower m.w. fractions were also recovered. With the P4 column, only one high m.w. (65–100%) and one low m.w. (0–53%) fraction were recovered; the total Al concentrations was 10–110 μg l^?1. When a hemofiltrate obtained from uremic patients on regular hemofiltration and spiked with 60–110 μg Al l^?1 was applied to the P4 gel, two lower m.w. fractions were detected. The adsorption/desorption of “free” aluminum on the column was studied with 0.9% NaCl solution, Earle's medium and filtrate. Normal column fractionation and frontal analysis (adsorption and desorption breakthrough curves) were used. Redistribution of aluminum seemed not to occur within the serum when in contact with the column, but contamination from extraneous aluminum could greatly alter the aluminum distribution. Different sources of errors were identified.8     

Analysis of size-classified fine and ultrafine particulate matter on substrates with laser-induced breakdown spectroscopy

Airborne particulate matter in the fine (0.1 µm–2.5 µm) and ultrafine (≤ 0.1 µm) size range is supposed to affect human health significantly. Smaller particles intrude more deeply into the lungs, so that an organism directly absorbs toxic compounds. Therefore, knowledge of the size-dependent composition of airborne particles is required to determine their health hazard. In this paper, we demonstrate the application of laser-induced breakdown spectroscopy to directly analyze size-classified particulate matter samples without any sample preparation. Samples analyzed are collected on filter substrates using a cascade impactor. Greased aluminum foils are used as filter substrate. To reduce ablation of the substrate material, low pulse energies of 0.6 mJ are used for plasma excitation. The plasma light is observed using an Echelle spectrometer. The effect of ambient gas and pressure on the line intensities is studied. Calibration samples for 14 elements relevant for human health were produced, and the system was calibrated for concentration ranges up to four orders of magnitude. Finally, the collected samples of particulate originating from steel-making processes were analyzed. The measurements show that the composition of these particles depends strongly on their size. For example, the elements lead, cadmium and copper are enriched within particles of about 200 nm diameter.     

Atomic emission spectrometric analysis of airborne particulate matter by direct nebulization of suspensions into the inductively-coupled plasma

A method is described for the rapid, direct emission spectrometric determination of iron in airborne particulate matter collected on polystyrene fiber filters using a conventional high-volume sampler and a Japanese low-volume sampler. The suspension prepared by dissolving the filter material in xylene was directly nebulized into the inductivelycoupled plasma excitation source. An ultrasonic immersion device was used for stirring purposes. Particles within the size range 0.1–100 μm in diameter are collected on the high-volume filters, while the largest particles on low-volume filters do not exceed 10 μm in diameter. The difference in the particle size composition entailed the use of a separate set of standard suspensions for each sample type. Standard suspensions for calibration were prepared from NBS SRM-1648 (urban particulates) as originally received and from its ground powder for high-volume and low-volume samples, respectively. The relative standard deviation was usually below 5%, which is acceptable for large-scale air pollution survey work. The possibility of determining other major and minor elements in airborne particulate matter was also examined.     

Combustion of aluminum particles in a high-temperature furnace under various O2/CO2/H2O atmospheres

The study focusing on the combustion of flowing aluminum particles and the properties of condensed phase products has important guiding significance for the practical application of aluminum-based propellants. Based upon an in-house built dynamic combustion experimental system, the dynamic combustion process of aluminum particles and the properties of condensed phase products under different atmospheres were studied in detail. The microstructure, size distribution and active aluminum content of samples were analyzed by field emission scanning electron microscopy, laser particle analyzer and inductively coupled plasma atomic emission spectroscopy. By monitoring the temperature distribution at different points in the furnace, the heat release of the samples at different positions is approximated, and the combustion efficiency is calculated. In the atmosphere containing CO₂, the maximum combustion efficiency can reach the value of 94.41%, followed by that in H₂O atmosphere, which had the value of 81.19%. Finally, under the N₂ containing atmosphere, the combustion is the weakest, and has the value of only 53.91%, confirming that the combustion followed the following descending order: CO₂?>?H₂O?>?N₂. The condensed phase products were mainly composed of agglomerates formed by the aggregation of particles and alumina smoke. It is well known that the reaction of the sample in the furnace not only follows the melt-dispersion mechanism, but also the diffusion mechanism. The high-speed camera captured four typical combustion forms of aluminum particles during flow, which are stable combustion, release of alumina smoke, crushing and extinction. The average burning time of four stages were studied. The two reaction mechanisms occurring under the same reaction conditions are determined by the nature of aluminum particles themselves.

     

Determination of Heavy Metals and Other Water Quality Parameters from the South China Sea

This study investigated the distribution and concentrations of chromium, copper, arsenic, zinc, cadmium, and lead in seawater and suspended particles in the South China Sea by collection of samples from different depths at sixteen stations. The salinity, temperature, pH, dissolved organic carbon, dissolved oxygen, and silicon concentration were also measured in seawater. The results showed that the concentration levels in seawater from 0 m to 4000 m followed this pattern: zinc > arsenic > copper > lead > chromium > cadmium. Significant correlations were observed between lead and chromium and between arsenic, cadmium, and lead at r > 0.728. Very weak correlations were observed between copper and arsenic and between copper and cadmium. The concentrations of dissolved metals and particulate metals had negative correlations except for zinc. The metal concentrations in seawater and suspended particles showed different correlation behavior with salinity, temperature, pH, dissolved oxygen, dissolved organic carbon, and silicon.     

Nonlinear viscoelasticity, percolation and particles dispersibility of PVA/aluminum hydroxide composite gels

We investigated the rheological properties of a composite gel consisting of poly(vinyl alcohol) and aluminum hydroxide particles, and discussed the relation among nonlinear viscoelasticity, percolation and particles dispersibility. The dynamic viscoelastic measurements revealed that the storage modulus at volume fractions ? < 0.04 satisfied with the Krieger-Dougherty equation representing random dispersion of particles. The storage modulus did not show any nonlinear viscoelastic response at ? < 0.04. However, the storage modulus at ? > 0.06 took a value which is far larger than that expected by the equation, indicating heterogeneous distribution of particles. Additionally, the nonlinear viscoelastic response was recognized clearly at ? > 0.06, suggesting a partial contact between particles. The storage modulus at ? > 0.18 showed a further increase satisfied with the percolation theory, therefore, the volume fraction is considered to be the percolation threshold of 3-dimension. Microscopic observations of the gel showed a clear network with a mesh size of few μm that is considered to be a partial network of particles.     

Characterization and kinetic performance of 2.1 × 100 mm production columns packed with new 1.6 μm superficially porous particles

The overall kinetic performance of three production columns (2.1 mm × 100 mm format) packed with 1.6 μm superficially porous CORTECS‐C₁₈+ particles was assessed on a low‐dispersive I‐class ACQUITY instrument. The values of their minimum intrinsic reduced plate heights (h_min = 1.42, 1.57, and 1.75) were measured at room temperature (295 K) for a small molecule (naphthalene) with an acetonitrile/water eluent mixture (75:25, v/v). These narrow‐bore columns provide an average intrinsic efficiency of 395 000 plates per meter. The gradient separation of 14 small molecules shows that these columns have a peak capacity about 25% larger than similar ones packed with fully porous BEH‐C₁₈ particles (1.7 μm) or shorter (50 mm) columns packed with smaller core–shell particles (1.3 μm) operated under very high pressure (>1000 bar) for steep gradient elution (analysis time 80 s). In contrast, because their permeabilities are lower than those of columns packed with larger core–shell particles, their peak capacities are 25% smaller than those of narrow‐bore columns packed with standard 2.7 μm core–shell particles.     

Association of uranium with colloidal and suspended particulate matter in Arabian sea near the west coast of Maharashtra (India)

The purpose of the present study is the association of natural uranium in seawater with colloidal and suspended-particulate matter was determined. The separation of suspended particulate material (>0.45 µm) and colloidal fraction (as dissolved fractions) in seawater were done by suction and ultra filtration techniques. Seawater samples were collected at 1 km away from the shore and subjected to sequential fractionation in nine stages ranging from 2.7 µm to 1.1 nm. Suspended particulate matter were separated in three different size groups namely >2.7 µm, <2.7–>0.45 µm and <0.45–>0.22 µm by suction filtration using cellulose acetate and nitrate membranes filters. To concentrate the solution with colloidal particles <0.22 µm–1.1 nm (0.5 k Nominal Molecular Weight cut-off Limit {NMWL}), the solution obtained from filtration through <0.22 µm was passed through stirred ultra-filtration cell. The pH and conductivity at different stages of fractionation (dissolved) showed minor variations. The concentration of uranium was measured in suspended and dissolved fractions by using a pulsed nitrogen laser at 337.1 nm. In order to evaluate the role of mineral colloids in various stages of filtration, concentration of calcium, magnesium, potassium were measured by using ion chromatography and atomic absorption spectrometry. The clay mineral at seawater pH (approximately 8) behave as negative ions and provides binding site for the positively charge species of uranium. Among the dissolved fraction, the maximum concentrations of colloidal uranium was observed about 4 times higher than that compared to average concentration of 6.93±3.10 ppb in other fractions. In the case of suspended particulate matter, the concentration of uranium was below detection limits (<1 ppb). The maximum concentration of Ca, Mg and K in the dissolved fraction were in the <1.1 nm fraction, while for suspended particulate matter, the concentration of Ca, Mg and K decreased with the decrease in size and it is highest in the fraction of 0.22 –0.45 µm.This revised version was published online in November 2005 with corrections to the Cover Date.     

Study of phosphorus distribution in coastal surface sediment by sequential extraction procedure (NE Mediterranean Sea, Antalya-Turkey)

The paper presents the results of the distribution of phosphorus (P) bioavailability (total P, organic and inorganic P) in marine surface sediments collected from four coasts that are under different anthropogenic pressures of NE Mediterranean Sea (Alanya, Serik, Kemer, Finike — Antalya, Turkey) in May, 2009. Speciation of inorganic phosphorus (IP) was carried out using a method on sequential extractions, with each releasing four forms of IP — loosely bound P, phosphorus bound to aluminum (P-Al), phosphorus bound to iron (P-Fe), and phosphorus bound to calcium (P-Ca) and determined by the inductively coupled plasma-optical emission spectrometer (ICP-OES). The total P contents ranged from 152.18 to 275.12 mg/kg. It was found that more than 96% of the total P is IP. Among the four forms of IP, IP distribution ranges were 1.20-3.59% for loosely bound P, 2.38-4.74% for P-Fe, 4.43-8.55% for P-Al, and 84.36-91.99% for P-Ca. The region of Alanya was characterized by the highest total P concentration in the surface sediment than Serik, Kemer, Finike sediments. For all the marine surface sediment samples, the rank order of inorganic P-fractions was Ca-P > Al-P > Fe-P > loosely bound P.     

Tunable magnetophoretic method for distinguishing and separating wear debris particles in an Fe-PDMS-based microfluidic chip

Wear debris analysis provides an early warning of mechanical transmission system aging and wear fault diagnosis, which has been widely used in machine health monitoring. The ability to detect and distinguish the ferromagnetic and nonmagnetic debris in oil is becoming an effective way to assess the health status of machinery. In this work, an Fe-poly(dimethylsiloxane) (PDMS)-based magnetophoretic method for the continuous separation of ferromagnetic iron particles by diameter and the isolation of ferromagnetic particles and nonmagnetic particles with similar diameter by type is developed. The particles experience magnetophoretic effects when passing through the vicinity of the Fe-PDMS where the strongest gradient of the magnetic fields exists. By choosing a relatively short distance between the magnet and the sidewall of the horizontal main channel and the length of Fe-PDMS with controlled particles flow rate, the diameter-dependent separation of ferromagnetic iron particles, that is, smaller than 7 µm, in the range of 8–12 µm, and larger than 14 µm, and the isolation of ferromagnetic iron particles and nonmagnetic aluminum particles based on opposite magnetophoretic behaviors by types are demonstrated, providing a potential method for the detection of wear debris particles with a high sensitivity and resolution and the diagnostic of mechanical system.     

Catalytic effects of Fe,Al and Si on the formation of NO<Subscript>X</Subscript> precursors and HCl during straw pyrolysis

The catalytic effects of iron, aluminum or silicon on the formation of NO_X precursors (HCN, NH₃ and HNCO) and HCl during wheat straw pyrolysis were studied using a thermogravimetric analyzer (TG) coupled with a Fourier transform infrared (FTIR) spectrometer in argon atmosphere. The results show that the presence of iron, aluminum or silicon decreases conversion of straw-N into NH₃ with the sequence of Fe > Si > Al. The iron or silicon addition suppresses N-conversion into HCN and HNCO, and the aluminum addition has no notable influence on HCN emission during pyrolysis. The share of N-conversion to NH₃ and HCN increases, but that to HNCO and NO decreases a little in the presence of added iron, aluminum or silicon. The addition of SiO₂ results in the highest HCl removal efficiency.     

Study of the spectral properties of inhomogeneous granular materials

The variation of the spectral properties of semi-transparent (polystyrene: PS), transparent (potassium bromide: KBr) and opacified particles (silver coated silica spheres: Ag-SiO₂) is presented from 0.25 to 20 μm. The spectral properties of binary mixtures PS/KBr and PS/Ag-SiO₂ are also studied. The sensitivity of the spectral properties to the particle diameters causes the near-normal hemispherical spectral reflectance R to decrease when the particle size increases from 10 to 1800 μm. The addition of KBr transparent particles to PS powders results in an increase in the reflectance values of the mixtures in the near and mid-infrared wavelength range. Furthermore, the effect of the addition of opacified reflecting particles depends on the wavelength region and on the PS content ([PS]). For < < 1.64 μm, R decreases when [PS] decreases from 1 to 0.56 and then R increases for [PS] values decreasing from 0.56 to 0. For < > 1.64 μm, R decreases when PS content increases from 0 to 1.     

Determination of trace-metal concentrations in size-classified atmospheric particles by ETV-ICP-MS

Atmospheric particles were sampled and fractionated according to their size by a cascade impactor in Berlin, capital city of Germany, on the Brocken, peak of the Harz mountains and on the Szrenica peak in the Giant mountains, Republic Poland. The fractionated particles were collected on small graphite targets and subsequently analyzed by ETV-ICP-MS. Distribution curves were measured showing trace-metal contents in air versus the aerodynamic particle diameter for the elements Pb, Ag, Cd and Tl. Despite good element correlation, the distribution curves differ significantly for the three sampling locations. The limits of detection for the elements of concern were in the pg/m³ range at a sampling time of 4 h. An attempt was made to determine single particles: in urban aerosols a content was found of 1 · 10^–13 g Tl and 9 · 10^–13 g Ag in single particles of the size fraction < 7.5 μm and > 3.45 μm.     

On-line analysis of ambient air aerosols using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy is developed for the detection of aerosols in ambient air, including quantitative mass concentration measurements and size/composition measurements of individual aerosol particles. Data are reported for ambient air aerosols containing aluminum, calcium, magnesium and sodium for a 6-week sampling period spanning the Fourth of July holiday period. Measured mass concentrations for these four elements ranged from 1.7 parts per trillion (by mass) to 1.7 parts per billion. Ambient air concentrations of magnesium and aluminum revealed significant increases during the holiday period, which are concluded to arise from the discharge of fireworks in the lower atmosphere. Real-time conditional data analysis yielded increases in analyte spectral intensity approaching 3 orders of magnitude. Analysis of single particles yielded composition-based aerosol size distributions, with measured aerosol diameters ranging from 100 nm to 2 μm. The absolute mass detection limits for single particle analysis exceeded sub-femtogram values for calcium-containing particles, and was on the order of 2–3 femtograms for magnesium and sodium-based particles. Overall, LIBS-based analysis of ambient air aerosols is a promising technique for the challenging issues associated with the real-time collection and analysis of ambient air particulate matter data.     

Concentrations of aluminium, iron, and copper in water of some Shatskiye Lakes and specificity of their distribution among different forms of occurrence

The results of studies on the occurrence of aluminum, iron, and copper in water of Lyutsimir and Chernoe Bol’shoe Lakes belonging to the large group of Shatsk Lake system are discussed. Iron was shown to migrate mostly as suspended particles, and copper, as soluble species. The average annual fraction of suspended aluminum is about 40%. The ratio of suspended and dissolved aluminum depends not only on the concentration of suspended particles in water, but also on their nature. Anionic complexes predominate among soluble forms of the examined metals; their fractions in water of Lyutsimir and Chernoe Bol’shoe Lakes are on the average 86 and 70% (Al), 73 and 59% (Cu), and 60 and 47% (Fe). This is determined by the major contribution of humic substances to the total content of organic matter in water of both lakes and their participation in the complexation with metals. The metals compete for active centers in humic macroligands. Carbohydrates constitute the second important group of organic substances that participate in the complexation. Neutral complexes were found to consist mainly of iron compounds. Compounds with a molecular weight not exceeding 2.0 kDa predominate among anionic metal complexes.     

Monodisperse Poly (Styrene-co-Divinylbenzene) Particles (3.2 μm) with Relatively Small Pore Size as HPLC Packing Material

Monodisperse 3.2-μm porous poly(styrene-co-divinylbenzene) particles have been prepared by a new multistage polymerization procedure, so-called ‘modified seeded polymerization’. In the synthesis of the particles sufficient porosity was generated by use of a diluent mixture with relatively low viscosity. The use of relatively high diluent/seed latex ratio resulted in the formation of particles with an average pore size of 13 nm. The particles were used as column-packing material in HPLC and their performance was compared with that of larger particles (d _n = 7.8 μm) obtained by the same method. The SEC plot for the 3.2 μm particles showed that the proposed material was particularly suitable for separation of analytes in the molecular weight range 100–2000. In reversed-phase mode alkylbenzenes were separated with resolution >2 by use of a relatively small column (50 mm × 4.6 mm i.d.) packed with 3.2-μm particles. Theoretical plate numbers (TPN) in excess of 35 000 plates m^?1 could be achieved with benzene as analyte. Whereas the ratio of TPN determined with pentylbenzene to that determined with benzene was less than 0.7 for the 7.8-μm particles, the same ratio was 0.95 for the 3.2-μm particles. With the 3.2-μm packing material proposed no significant decrease in resolving power was observed when the mobile-phase flow rate was increased sevenfold.     

Effects of magnetic particles and carbon black on structure and properties of magnetorheological elastomers

Isotropic magnetorheological elastomers (MREs) consisting of ethylene-propylene-diene monomer (EPDM), carbon black and two different micron-sized iron particles (carbonyl iron powder (CIP) and bare iron powder (BIP)) were prepared for dynamic automotive applications such as tunable engine mounts, vibration absorbers and suspension bushings. The sample that contains 5 phr CIP and 60 phr carbon black has the best tensile strength, elongation at break and elastic modulus and the highest MR effect of 77%. Based on SEM and EDS, homogenous distribution of single CIP and its aggregates of 8 μm and larger BIP aggregates of 15–20 μm were observed with 30 phr loadings of CIP and BIP, respectively. EPDM/carbon black/CIP MREs show significant property improvements compared to EPDM/carbon black/BIP MREs. The system containing CIP particles has substantially lower damping factor, Payne effect, elastic modulus, hardness, aggregation behavior and higher tensile strength and elongation at break values compared to BIP system.     

The determination of hydrogen chloride in ambient air with diffusion/denuder tubes

A manual method for the determination of hydrogen chloride in air, based on diffusion/denuder tube separation from particulate chloride aerosol is described. When air is drawn through a tube coated with a selective absorbent (sodium fluoride), separation is achieved because gaseous hydrogen chloride diffuses much more rapidly to the tube walls than particulate chloride aerosol, which passes through virtually unabsorbed. After the sampling period (the length of which depends on the concentration of gaseous hydrogen chloride expected), the sorbed hydrogen chloride is washed from the tube and measured with a highly sensitive chloride ion-selective electrode with a mercury (I) chloride membrane. The method is examined theoretically and experimentally. The experimentally derived absorption efficiencies of the diffusion/denuder tubes were > 90% and the standard deviation of the method was 0.023 μg m^?3 for hydrogen chloride concentrations of 0.16–0.55 μg m^?3. Interference from particulate chloride salts was negligible; this was confirmed by tests with artificially generated aerosol particles from an aerosol generator. The diffusion/denuder tubes have high capacity; level as high as 330 μg m^?3 hydrogen chloride can be sampled for 60 min without affecting performance. A detection limit of (50/t) μg m^?3 can be achieved, where t is the sampling rime (min); e.g., 1μg m^?3 hydrogen chloride can be detected with a sampling period of 50 min.     

Particle Size Determination of Trace Elements in Urban Air

Abstract

Airborne urban particulate matter was collected and fractionated according to size by cascade impactors. The elements zinc, cadmium, copper and lead on each size fraction were analyzed by anodic stripping voltammetry. The elements aluminum, iron, manganese, calcium and magnesium were analyzed by atomic absorption spectrophotometry. The data showed three different classes of particle size distribution for these nine elements. Lead and cadmium belonged to the first class with more than 70 % of the total collected element associated with particles having aerodynamic diameters below 0.5 micron. The calculated average mass median equivalent diameter (MMD) of cadmium and lead was approx. 0.1 micron. In the second class about 60% of the elements Zn, Cu, Mg and Fe was associated with particles smaller than 0.5 micron. The average MMD's for these elements were between 0.3 and 0.4 micron. For the elements Al, Ca and Mn about 50% of the metal was associated with particles smaller than 0.5 micron and the MMD's were between 0.5 and 0.6 micron. Examination of elemental ratios (using Al as a reference element) showed that Pb and Cd were about 1000 times more concentrated in atmospheric particulate matter than in average crustal material and that in general the Pb/Al and Cd/Al ratios are inversely proportional to particle size. The Zn/Al and Cu/Al ratios of atmospheric partides were age or less independent of particle size and approx. 20 times higher than these same ratios in average crustal material. The ratios Fe/Al, Mn/AI, Ca/M and Mg/AI in all sizes of particulate matter were essentially identical to the same ratios in average crustal material.     

The heterometric micro-determination of copper with quinaldic acid in the presence of foreign metals

1. During the heterometric determination of copper, bivalent cations may be present in solution in large excesses (>95%) and no complexing agents are necessary. In the presence of zinc, excesses of citrate of tartrate must be added. Error: 0—2 %. 2. Excesses of chromium or aluminum (>95%) are without effect. In the presence of an excess of iron (>95%) the determination is made by the addition of tartrate which increases the maximum density value obtained. Error: 0—3%.