Speciation of inorganic and organotin compounds in biological samples by liquid chromatography with inductively coupled plasma mass spectrometric detection

This paper describes the effect of inorganic tin chloride on the separation of trimethyl-, tributyl- and triphenyltin-chlorides by reversed-phase ion-pair high-performance liquid chromatography with detection by inductively coupled plasma mass spectrometry. The detection limits are 1.6 pg, 1.5 pg and 2.3 pg as tin for trimethyltin, tributyltin and triphenyltin, respectively. The relative standard deviation for ten injections of 20 ng of the tin compounds was less than 5%. Inorganic tin was held strongly on the columns used, to a greater extent on the silica column compared to the polymer column. Extraction and determination of tributyltin and triphenyltin as chlorides in fish tissue (certified reference material) and tuna fish (grocery store) were performed. The recovery study from fish tissue showed an efficiency of over 90% for both tributyltin and triphenyltin and over 60% recovery for spiked tuna.

Butyltins, polyaromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls in sediments and bivalve mollusks in a mid-latitude environment from the Patagonian coastal zone

Butyltins (BTs), polyaromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) were assessed in a mid-latitude environment of the Patagonian coast, distant from significant pollutant sources. Bioaccumulation processes through bottom sediment resuspension were suggested by BTs level (expressed as ng of tin [Sn] g(-1) dry wt) found in surface sediment (<limit of detection [LOD]-166.5 ng [Sn] g(-1) dry wt) and bivalve mollusks (29.4-206.0 ng [Sn] g(-1) dry wt); whereas imposex incidence was only 15% in the gastropod Pareuthria plumbea collected near a harbor. Low hydrocarbon pollution was found in sediments and bivalves with ∑PAHs(16) ranging from <LOD to 94.9 ng g(-1) dry weight and from <LOD to 54.9 ng g(-1) dry weight, respectively. Values were typical of locations distant from pollutant sources and showed different compositional patterns for both substrates. However, concentrations for some individual PAHs in sediments were found over the threshold effect level. On average, ΣPCB did not exceed the sediment quality guidelines being 0.57 ± 0.88 ng g(-1) dry weight in sediments and 0.41 ± 0.26 ng g(-1) dry weight in bivalves. Average ΣOCPs in sediments were 0.53 ± 0.34 ng g(-1) dry weight and ranged from <LOD to 0.22 ng g(-1) dry weight in bivalves, showing a different pattern and suggesting a different accumulation pathway as was found for PAHs. Although both discrete and atmospheric sources can be considered for PAHs, organochlorines pollution was clearly related to atmospheric global transport, indicating that in the studied area, OCPs and PCBs experience permanent or temporal deposition during their migration to southern zones.

A quantitative extraction method for the determination of trace amounts of both butyl- and phenyltin compounds in sediments by gas chromatography-inductively coupled plasma mass spectrometry

A simple and reliable extraction method was developed for quantitative determination of both butyl- and phenyltin compounds in sediments by capillary gas chromatography combined with inductively coupled plasma mass spectrometry (GC-ICP-MS). Both types of organotin compounds were extracted quantitatively from sediment by mechanical shaking into tropolone-toluene and HCl-methanol. After phase separation and pH adjustment, these organotins were ethylated with sodium tetraethylborate. The method was evaluated by analyzing PACS-2 and NIES No. 12 sediment certified reference materials. The dibutyltin (DBT; 1.14 +/- 0.02 micrograms g-1) and tributyltin (TBT; 1.01 +/- 0.04 micrograms g-1) values observed in PACS-2 sediment closely matched the certified values (DBT, 1.09 +/- 0.15; TBT, 0.98 +/- 0.13 microgram g-1 as tin). The monobutyltin (MBT) value was higher (0.62 +/- 0.02 microgram g-1) by more than two fold over the reference value (0.3 microgram g-1 as tin). The concentrations of TBT (0.18 +/- 0.04 microgram g-1) and triphenyltin (TPhT; 0.0099 +/- 0.002 microgram g-1) in the NIES No. 12 sediment were also in good agreement with the certified and reference values of TBT (0.19 +/- 0.03 microgram g-1 as compound) and TPhT (0.008 microgram g-1 as compound), respectively. Recoveries of TBT, tripentyltin (TPeT) and TPhT from spiked sediments were satisfactory (TBT, 102 +/- 3.4%; TPrT, 96 +/- 3.4%; TPhT, 99 +/- 8.5%). The detection limits as tin were in the range 0.23-0.48 ng g-1 for a 0.5 g sample size. It is also noteworthy that clean-up of the extract is not necessary because of the superior selectivity of ICP-MS detection. The present method was successfully applied to marine sediment samples.

Design and characterization of a biomass template/SnO2 nanocomposite for enhanced adsorption of 2,4-dichlorophenol

2,4-Dichlorophenol (2,4-DCP) is a hazardous chlorinated organic chemical derived from phenol that exerts serious effects on living organisms. In the present study, SnO₂ templated with grapefruit peel carbon as a nanocomposite (SnO₂@GPC) was designed via ball-milling, and its mechanism of 2,4-DCP adsorption in aqueous solution was determined. Batch adsorption experiments revealed that the maximum adsorption efficiency of SnO₂@GPC occurred at 6.0 pH, 3 mg L^-1 initial adsorbate concentration, 2 h contact time, and 293 K temperature. The SnO₂@GPC nanocomposite and its non-tin-bearing counterpart, grapefruit derived char (@GPC), showed maximum adsorption capacities (Q_L) of 45.95 and 22.09 mg g^-1 and partition coefficients of 41.77 and 10.83 mg g^-1 μM^-1, respectively. The adsorption of 2,4-DCP was best described by the Redlich-Peterson model followed by the Langmuir model with high correlation coefficients (R² ≥ 0.96), and the adsorption kinetic data best fitted the pseudo-second-order model (R² ≥ 0.98). The thermodynamic parameters indicated that the reaction was spontaneous, exothermic, and involved high affinity between SnO₂@GPC and 2,4-DCP. The high desorption efficiency obtained (>80%) demonstrated the recyclability of the adsorbent. The enhanced Q_L of SnO₂@GPC was due to the effective combination of GPC and SnO₂. A thin porous layer of GPC on SnO₂ nanoparticles provided effective channels, a large surface area, and an abundance of active sites for 2,4-DCP adsorption. Thus, the SnO₂@GPC nanocomposite could potentially be used as a low-cost adsorbent to remove 2,4-DCP from water.

Use of and occupational exposure to indium in the United States

Indium use has increased greatly in the past decade in parallel with the growth of flat-panel displays, touchscreens, optoelectronic devices, and photovoltaic cells. Much of this growth has been in the use of indium tin oxide (ITO). This increased use has resulted in more frequent and intense exposure of workers to indium. Starting with case reports and followed by epidemiological studies, exposure to ITO has been linked to serious and sometimes fatal lung disease in workers. Much of this research was conducted in facilities that process sintered ITO, including manufacture, grinding, and indium reclamation from waste material. Little has been known about indium exposure to workers in downstream applications. In 2009-2011, the National Institute for Occupational Safety and Health (NIOSH) contacted 89 potential indium-using companies; 65 (73%) responded, and 43 of the 65 responders used an indium material. Our objective was to identify current workplace applications of indium materials, tasks with potential indium exposure, and exposure controls being used. Air sampling for indium was either conducted by NIOSH or companies provided their data for a total of 63 air samples (41 personal, 22 area) across 10 companies. Indium exposure exceeded the NIOSH recommended exposure limit (REL) of 0.1 mg/m(3) for certain methods of resurfacing ITO sputter targets, cleaning sputter chamber interiors, and in manufacturing some inorganic indium compounds. Indium air concentrations were low in sputter target bonding with indium solder, backside thinning and polishing of fabricated indium phosphide-based semiconductor devices, metal alloy production, and in making indium-based solder pastes. Exposure controls such as containment, local exhaust ventilation (LEV), and tool-mounted LEV can be effective at reducing exposure. In conclusion, occupational hygienists should be aware that the manufacture and use of indium materials can result in indium air concentrations that exceed the NIOSH REL. Given recent findings of adverse health effects in workers, research is needed to determine if the current REL sufficiently protects workers against indium-related diseases.

Spectrophotometric determination of Sb(III) and Sb(V) in biological samples after micelle-mediated extraction

This work presents a micelle-mediated extraction method for simultaneous preconcentration and determination of Sb(III) and Sb(V) species in biological samples as a prior preconcentration step to their spectrophotometric determination. The analytical system is based on the selective reaction between Sb(III) and bromopyrogallol red (BPR) in the presence of cetyltrimethylammonium bromide (CTAB) and potassium iodide at pH 6.4. Total Sb concentration was determined after reduction of Sb(V) to Sb(III) in the presence of potassium iodide and ascorbic acid. The optimal extraction and reaction conditions were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration factor, and improvement factors) were obtained. Linearity for Sb(III) and Sb(V) were obeyed in the range of 0.2-20.0 ng mL(-1) and 0.4-25.0 ng mL(-1), respectively. The detection limit for the determination of Sb(III) and Sb(V) were 0.05 ng mL(-1) and 0.08 ng mL(-1), respectively. The interference effect of some anions and cations was also studied. The method was applied to the determination of Sb(III) in the presence of Sb(V) and total antimony in blood plasma and urine samples.

In situ experiments for element species-specific environmental reactivity of tin and mercury compounds using isotopic tracers and multiple linear regression

The fate of mercury (Hg) and tin (Sn) compounds in ecosystems is strongly determined by their alkylation/dealkylation pathways. However, the experimental determination of those transformations is still not straightforward and methodologies need to be refined. The purpose of this work is the development of a comprehensive and adaptable tool for an accurate experimental assessment of specific formation/degradation yields and half-lives of elemental species in different aquatic environments. The methodology combines field incubations of coastal waters and surface sediments with the addition of species-specific isotopically enriched tracers and a mathematical approach based on the deconvolution of isotopic patterns. The method has been applied to the study of the environmental reactivity of Hg and Sn compounds in coastal water and surface sediment samples collected in two different coastal ecosystems of the South French Atlantic Coast (Arcachon Bay and Adour Estuary). Both the level of isotopically enriched species and the spiking solution composition were found to alter dibutyltin and monomethylmercury degradation yields, while no significant changes were measurable for tributyltin and Hg(II). For butyltin species, the presence of light was found to be the main source of degradation and removal of these contaminants from surface coastal environments. In contrast, photomediated processes do not significantly influence either the methylation of mercury or the demethylation of methylmercury. The proposed method constitutes an advancement from the previous element-specific isotopic tracers' approaches, which allows for instance to discriminate the extent of net and oxidative Hg demethylation and to identify which debutylation step is controlling the environmental persistence of butyltin compounds.

Trace determination of organotin compounds in water, sediment and mussel samples by low-pressure gas chromatography coupled to tandem mass spectrometry

A fast method for the determination of eight organotin compounds (OTs), monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), tetrabutyltin (TeBT), monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT) and tetraphenyltin (TePhT), in water, sediments and mussels, was developed using low-pressure gas chromatography/tandem mass spectrometry (LPGC/MS/MS). The method is based on sodium diethyldithiocarbamate (DDTC) complexation of the ionic organotins, followed by extraction of the target matrices and derivatization by a Grignard reagent, as described in a previously published method for water samples. Solid-phase extraction was selected as extraction method from water samples after comparison with liquid-liquid extraction, but extraction of the OTs from sediment and mussel samples was performed using toluene. Matrix-matched calibration standards were used to minimize matrix effects. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, detection limit (LOD), quantitation limit (LOQ), precision, and recovery were determined. Recoveries of OTs in spiked matrices ranged from 86-108% in water and from 78-110% in sediments and mussels, with precision values lower than 18%. Detection limits ranged from 0.1-9.6 ng L(-1) in water, and 0.03-6.10 microg kg(-1) in the other matrices. The present implementation of LPGC rather than conventional capillary GC permitted use of large-volume injection and reduced analysis time by a factor of two. The proposed methodology was applied to the determination of OTs in real samples of water, marine sediments and mussels from the west coast of the Mediterranean Sea (Spain).

Large-scale hydrothermal synthesis of SnS2 nanobelts

SnS2 nanobelts were successfully synthesized through a controllable solution-phase hydrothermal method on a large scale. The nanobelts have a very high yield, which is more than 95%, with widths ranging from 100 to 200 nanometers, lengths up to several micrometers and thicknesses ca. 10 nanometers. X-ray diffraction patterns, electronic diffraction, X-ray photoelectron spectra, field emission scanning electron microscopy images, transmission electron microscopy images and high-resolution transmission electron microscopy investigated the phase structures, compositions, and morphologies of SnS2 nanobelts. Dodecanethiol played important roles in the process of SnS2 nanobelts formation and growth. The formation mechanism of SnS2 nanobelts was investigated and discussed on the basis of the experimental results.

Surface characterization of amalgam made with Hg-In liquid alloy

When amalgam was triturated with Hg-In liquid alloys instead of pure mercury, the resultant amalgams released a significantly smaller amount of mercury vapor during setting. To understand the mechanisms responsible for the drastic decrease in mercury evaporation from the In-containing amalgam, we used Auger Electron Spectroscopy to examine surface oxide films on amalgams made with Hg-10 wt% In or pure mercury. The surface of the In-containing amalgam was rapidly covered with both indium and tin oxide films. Greater amounts of oxygen were found on the gamma 1 Ag-Hg matrix in the In-containing amalgam than in the amalgam without indium. The rapid formation of the oxide film contributes to a reduction in the mercury release from the In-containing amalgam by forming an effective barrier to evaporation.

Bioavailability of CeO2 and SnO2 nanoparticles evaluated by dietary uptake in the earthworm Eisenia fetida and sequential extraction of soil and feed

The growing number of nanotechnology products on the market will inevitably lead to the release of engineered nanomaterials with potential risk to humans and environment. This study set out to investigate the exposure of soil biota to engineered nanoparticles (NPs). Cerium dioxide (CeO2 NPs) and tin dioxide nanoparticles (SnO2 NPs) were radiolabelled using neutron activation, and employed to assess the uptake and excretion kinetics in the earthworm Eisenia fetida. Through sequential extraction, NPs bioavailability in two contrasting soils and in earthworm feed was also investigated. Neither CeO2 NPs nor SnO2 NPs bioaccumulated in earthworms, and both were rapidly excreted when worms were transferred to clean soil. Low bioavailability was also indicated by low amounts of NPs recovered during extraction with non-stringent extractants. CeO2 NPs showed increasing mobility in organic soil over time (28 days), indicating that organic matter has a strong influence on the fate of CeO2 NPs in soil.

Assessing weak intramolecular donor-acceptor interactions using 1H-117Sn J-HMQC spectroscopy

It is demonstrated that long-range nJ(1H,117Sn) coupling constants down to 0.3 Hz, can be accurately quantified from non-linear fitting of the sine modulation of the associated 1H-117Sn correlation cross-peak intensities sampled as a function of the heteronuclear antiphase coherence preparation time in the 1H-117Sn J-HMQC pulse sequence. The contribution of additional, undesired modulations is illustrated and assessed using the product operator formalism, and is traced back to contributions that arise from miss-setting of the wandering 180 degrees pulse angle in the constant time period. The power of the method and its use in the characterization of weak intramolecular donor-acceptor interactions are illustrated by the determination of long-range nJ(1H,117Sn) coupling constants of bis[3-(dimethylamino)propyl]tin derivatives, [Me2N(CH2)3]2SnR2 (', R = Me; 3, R = Ph; 4, R = t-Bu). By comparing these with the values found for the corresponding bis(4-methylpentyl)tin derivatives, [Me2CH(CH2)3]2SnR2 (2', R = Me; 3', R = Ph), which lack such interactions, the use of long-range coupling constants to detect intramolecular donor-acceptor interactions is evaluated. It is concluded that nJ(1H,117Sn) couplings up to six bonds through an organic carbon chain can be quantified, whether donor-acceptor interactions are present or not. Furthermore, evidence is presented that, when two scalar coupling pathways co-exist, the pathway involving an intramolecular donor-acceptor interaction can have opposite sign, thus decreasing the overall coupling constant to a value smaller than that actually measured in the absence of a donor-acceptor interaction, where only one coupling pathway is active. There is nevertheless clear numerical value discrimination in the series of compounds investigated between long-range couplings in derivatives without weak intramolecular donor-acceptor interactions and those where such interactions can exist.

Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes

Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11kg/m(3) of copper and 1.35kg/m(3) of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100-500nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with>99% efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process.

Radiolabelling of egg meals for gastric emptying studies: a comparison of 99mTc sulfur and 99mTc stannous colloids

OBJECTIVES

To establish whether 99mTc stannous (Tc-Sn) colloid is a suitable alternative to 99mTc sulfur (Tc-S) colloid for gastrointestinal studies, we compared the per cent binding to egg solids (%BS) and radiochemical purity (RCP) of both colloids in digesting media.

METHODS

Egg white and yolk containing colloids were cooked separately and mashed. Samples of 4-5 g were digested over 2-3 h (37 degrees C) in excess simulated gastric juice (SGJ: 15 ml of 0.1 M HCl and 0.5 g.l-1 pepsin) or water, centrifuged, imaged with a gamma camera and the %BS computed. RCP was determined in aspirates taken from these preparations and from solutions of colloid added directly to SGJ.

RESULTS

The %BS in egg white after 3 h in SGJ for both colloids were similar: Tc-Sn, 62+/-8 (n=12); Tc-S, 61+/-6 (n=8), but markedly lower than 95% (the often quoted literature value). Egg yolk was digested more rapidly than egg white: %BS after 2 h in SGJ for Tc-Sn colloid was 55+/-10 (n=5) in the yolk, compared to 77+/-4 (n=5) in the white (P<0.01). The RCP for Tc-S colloid alone in SGJ was >94% over 3 h but for Tc-Sn colloid was as low as 14%. For egg white, the RCP in SGJ was 91-96% for Tc-S and 80-91% for Tc-Sn. For egg yolk the RCPs in SGJ were similar for both colloids (>90%). The RCP in water digesting egg white or yolk containing either colloid was always lower than in the corresponding SGJ aspirates, indicating a leakage of small amounts of non-colloidal 99mTc.

CONCLUSIONS

Although 99mTc-Sn almost completely dissociates in SGJ, once cooked in egg it is digested similarly to 99mTc-S. Variations in the size of digesting egg fragments and in SGJ composition can reconcile the lower %BS values obtained with previously reported higher results. 99mTc-Sn colloid cooked in egg appears suitable for gastrointestinal studies.

Continuous-wave terahertz system based on a dual-mode laser for real-time non-contact measurement of thickness and conductivity

Terahertz (THz) waves have been exploited for the non-contact measurements of thickness and refractive index, which has enormous industrial applicability. In this work, we demonstrate a 1.3-μm dual-mode laser (DML)-based continuous-wave THz system for the real-time measurement of a commercial indium-tin-oxide (ITO)-coated glass. The system is compact, cost-effective, and capable of performing broadband measurement within a second at the setting resolution of 1 GHz. The thickness of the glass and the sheet conductivity of the ITO film were successfully measured, and the measurements agree well with those of broadband pulse-based time domain spectroscopy and Hall measurement results.

Characterization and exposure measurement for indium oxide nanofibers generated as byproducts in the LED manufacturing environment

This article aimed to elucidate the physicochemical characteristics and exposure concentration of powder and airborne particles as byproducts generated from indium tin oxide thin film process by an electron beam evaporation method during maintenance in light-emitting diode manufacturing environment. The chemical composition, size, shape, and crystal structure of powder and airborne particles as byproducts were investigated using a scanning electron microscope equipped with energy dispersive spectrometer, and an X-ray diffractometer. The number and mass concentration measurements of airborne particles were performed by using an optical particle counter of direct-reading aerosol monitor and an inductively coupled plasma-mass spectrometry after sampling, respectively. The airborne particles are composed of oxygen and indium. On the other hand, the powder byproducts consist mostly of oxygen and indium, but tin was found as a minor component. The shapes of the airborne and powder byproducts were fiber type. The length and diameter of fibrous particles were approximately 500-2,000 nm and 30-50 nm, respectively. The powder byproducts indicated indium oxide nanofibers with a rhombohedral structure. On the other hand, the indium oxide used as a source material in the preparation of ITO target showed spherical morphology with a body-centered cubic structure, and it was the same as that of the pure crystalline indium oxide powder. During maintenance, the number concentrations ranged from 350-75,693 particles/ft(3), and arithmetic mean±standard deviation and geometric mean±geometric standard deviation were 11,624±15,547 and 4,846±4.12 particles/ft(3), respectively. Meanwhile, under the same conditions, the airborne mass concentrations of the indium based on respirable particle size (3.5 µm cut-point 50%) were 0.09-0.19 µg/m(3). Physicochemical characteristics of nanoparticle can affect toxicity so the fact that shape and crystal structure have changed is important. Thus, nanoparticle occupational toxicology greatly needs observations like this.

Reactivation and reuse of TiO2-SnS2 composite catalyst for solar-driven water treatment

One of the most important features of photocatalytic materials intended to be used for water treatment is their long-term stability. The study is focused on the application of thermal and chemical treatments for the reactivation of TiO₂-SnS₂ composite photocatalyst, prepared by hydrothermal synthesis and immobilized on the glass support using titania/silica binder. Such a catalytic system was applied in solar-driven treatment, solar/TiO₂-SnS₂/H₂O₂, for the purification of water contaminated with diclofenac (DCF). The effectiveness of studied reactivation methods for retaining TiO₂-SnS₂ activity in consecutive cycles was evaluated on basis of DCF removal and conversion, and TOC removal and mineralization of organic content. Besides these water quality parameters, biodegradability changes in DCF aqueous solution treated by solar/TiO₂-SnS₂/H₂O₂ process using simply reused (air-dried) and thermally and chemically reactivated composite photocatalyst through six consecutive cycles were monitored. It was established that both thermal and chemical reactivation retain TiO₂-SnS₂ activity in the second cycle of its reuse. However, both treatments caused the alteration in the TiO₂-SnS₂ morphology due to the partial transformation of visible-active SnS₂ into non-active SnO₂. Such alteration, repeated through consecutive reactivation and reuse, was reflected through gradual activity loss of TiO₂-SnS₂ composite in applied solar-driven water treatment.

A photoelectrochemical biosensor based on SnO2 nanoparticles for phosphatidylcholine detection in soybean oil

A photoelectrochemical (PEC) biosensor based on SnO₂ nanoparticles (SnO₂ NPs) was developed and applied for phosphatidylcholine (PC) detection in soybean oil. SnO₂ NPs were grown on an indium tin oxide (ITO) electrode, polythionine (PTh) was electropolymerized on the surface of ITO/SnO₂ NPs, and choline oxidase (ChO_x) was immobilized to prepare the ITO/SnO₂ NPs/PTh/ChO_x electrode. The developed PEC biosensor can detect PC under visible light irradiation. The experimental conditions for PC detection were as follows: 1.8 mg mL^-1 ChO_x concentration, 0.5 V bias voltage, 18 mW cm^-2 light intensity, and pH 6. The PEC biosensor had a detection limit of 0.005 mM (S/N = 3) and a detection range from 0.03 mM to 4 mM. This PEC biosensor based on SnO₂ NPs was applied to detect PC in soybean oil. The recovery rate tested by the standard addition method was 95.2-107.4%. These findings were consistent with the results obtained by high-performance liquid chromatography (HPLC). Therefore, the proposed PEC biosensor based on SnO₂ NPs has excellent reproducibility, stability, and great potential applications in the PEC analysis of PC in soybean oil.

N,N-diethyl-N'-benzoylthiourea--a new spectrophotometric reagent for rhenium determination

The reagent N,N-diethyl-N'-benzoylthiourea produces a green complex with rhenium in hydrochloric acid medium in the presence of tin(II) chloride. The complex extracted into toluene shows an absorption maximum at 383 nm, obeys Beer's law from 1.5 to 22 micrograms ml-1 of rhenium while its molar absorptivity and Sandell sensitivity are 6.66 x 10(3) L mol-1 cm-1 and 0.028 microgram cm-2, respectively. It tolerates the presence of a large number of ions, including Mo(VI), W(VI) and some platinum metals. Job's and the mole ratio methods indicate that the rhenium metal and the chelating agent ratio of 1:2 in solution. The system has been applied to the determination of rhenium on synthetic samples and alumina based catalysts.

[Study on the contamination level and intake of organotins of Chinese dietary]

OBJECTIVE

To obtain the baseline data of organotins' pollution of Chinese meal in order to carry on primary danger analysis of the exposure.

METHODS

The samples of the third Chinese total diet study were determined by gas-chromatography pulsed flame photometric detector to estimate dietary intake of organotins. The dietary intake of organotins was estimated according to the contamination level of organotins and food consumption.

RESULTS

Only several kinds of organotin were founded in several foods and no organotins was found in fruit, sugar and alcoholic beverages. Dimethyltin (DMT) were detected in some samples from Southern 1 area, the content ranged from 1.5 microg/kg to 4.1 microg/kg. Butyltin compounds existed in seafoods from Southern 1 area, the contents of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MTB) being 0.9 microg/kg, 1.1 microg/kg, 1.4 microg/kg respectively. The lower limit and upper limit of exposure to tributyltin were from 0.003 microg x kg(-1) x d(-1) to 0.006 microg x kg(-1) x d(-1) and from 0.004 microg x kg(-1) x d(-1) to 0.019 microg x kg(-1) x d(-1) respectively. Comparing to ADI of tributyltin (WHO), the Chinese dietary intake of tributyltin only accounted for 2.5% and that of butyltin only accounted for 3.5%. To identify the contamination source of organotins in Southern 1 area, the individual samples of aquatic food from individual province were analyzed, revealing that Fujian province and Shanghai City were the main contributors of organotins pollution in this area. The belt fish and yellow croaker were typical pollution samples. Higher levels of DMT were detected in seafood samples from Shanghai.

CONCLUSION

The exposure level of Chinese dietary was relative low, however the sources of organotin pollution needs further investigation.

Osseointegration of rough acid-etched implants: one-year follow-up of placement of 100 minimatic implants

Between January 1992 and October 1992, 100 Minimatic screw implants made of titanium alloy with rough acid-etched surfaces were placed in 63 consecutive partially edentulous patients. At second-stage (uncovering) surgery performed after a 4- to 6-month healing period, none of the implants showed any signs of mobility, peri-implant infection, or bone loss. After an additional healing phase averaging 2 weeks, the patients were restored with fixed prostheses. Patients were reexamined every 3 months for 1 year, with all 63 patients available for evaluation during this period. Periapical radiographs were taken preoperatively, immediately after surgery, and at 6 and 12 months after implantation. There were no signs of peri-implant radiolucencies in any of the implants, and alveolar bone loss was less than 1 mm on average 1 year after implantation. Based on Plaque Index, sulcular bleeding index, pocket probing depth, attachment level, width of keratinized mucosa, and hand-tested mobility, 99 implants were considered successful and 1 (which developed peri-implant infection) was considered a failure. Study results substantiate other reports that implants with a rough surface can yield predictable good results.

Establishing Healthy Breath Baselines With Tin Oxide Sensors: Fundamental Building Blocks for Noninvasive Health Monitoring

INTRODUCTION

Volatile organic compounds (VOCs) in breath serve as a source of biomarkers for medical conditions relevant to warfighter health including Corona Virus Disease and other potential biological threats. Electronic noses are integrated arrays of gas sensors that are cost-effective and miniaturized devices that rapidly respond to VOCs in exhaled breath. The current study seeks to qualify healthy breath baselines of exhaled VOC profiles through analysis using a commercialized array of metal oxide (MOX) sensors.

MATERIALS AND METHODS

Subjects were recruited/consented through word of mouth and using posters. For each sample, breath was analyzed using an array of MOX sensors with parameters that were previously established. Data were also collected using a lifestyle questionnaire and from a blood test to assess markers of general health. Sensor data were processed using a feature extraction algorithm, which were analyzed through statistical approaches to identify correlations with confounding factors. Reproducibility was also assessed through relative standard deviation values of sensor features within a single subject and between different volunteers.

RESULTS

A total of 164 breath samples were collected from different individuals, and 10 of these volunteers provided an additional 9 samples over 6 months for the longitudinal study. First, data from different subjects were analyzed, and the trends of the 17 extracted features were elucidated. This revealed not only a high degree of correlation between sensors within the array but also between some of the features extracted within a single sensor. This helped guide the removal of multicollinear features for multivariate statistical analyses. No correlations were identified between sensor features and confounding factors of interest (age, body mass index, smoking, and sex) after P-value adjustment, indicating that these variables have an insignificant impact on the observed sensor signal. Finally, the longitudinal replicates were analyzed, and reproducibility assessment showed that the variability between subjects was significantly higher than within replicates of a single volunteer (P-value = .002). Multivariate analyses within the longitudinal data displayed that subjects could not be distinguished from one another, indicating that there may be a universal healthy breath baseline that is not specific to particular individuals.

CONCLUSIONS

The current study sought to qualify healthy baselines of VOCs in exhaled breath using a MOX sensor array that can be leveraged in the future to detect medical conditions relevant to warfighter health. For example, the results of the study will be useful, as the healthy breath VOC data from the sensor array can be cross-referenced in future studies aiming to use the device to distinguish disease states. Ultimately, the sensors may be integrated into a portable breathalyzer or current military gear to increase warfighter readiness through rapid and noninvasive health monitoring.

[Determination of inorganic and organic tin in water samples by graphite furnace atomic absorption spectrometry]

This paper proposed a method for the determination of inorganic tin and organotin species. Total tin contents can be directly detected by zirconium-coated graphite furnace atomic absorption spectrometry,while the organotin was detected by hydride generation combined with solvent extraction and the difference between the total tin and organotin was inorganic tin. The detection limits were 58 pg and 27 pg for organotin and inorganic tin,respectively. The relative standard deviations of this procedure, were 2.13% and 2.04%, respectively. Several water samples were analyzed by this method. The recoveries ranging from 90.5% and 98.5% were obtained.

Electrical heating synchronized with IR imaging to determine thin film defects

Measuring conductive thin film properties during production and in end products is a challenge. The main demands for the measurements are: production control, reliability and functionality in final applications. There are several ways to measure thin film quality in a laboratory environment, however these methods are poorly applicable for production facilities. In order to bypass the limitations of existing methods, a simple synchronized heating and IR-imaging based system was implemented. To demonstrate the proposed method, Indium Tin Oxide (ITO) was selected as an example of conductive thin films. PET-ITO films were bent to obtain samples with defects. The proposed method was used and automated signal processing was developed. The results show that the system developed here is suitable for defining breakage types and localizing defects.