Inductively Coupled Plasma Mass Spectrometry Results Research Articles

Expanding the use of portable XRF to monitor lead exposure in an Australian duck species two decades after a ban on lead shot

There is growing worldwide recognition of the threat posed by toxic lead for wildlife and humans. Lead toxicity from ammunition has been shown to be a threat to waterbirds across the globe. Lead shot was banned for all waterfowl hunting in Victoria, Australia, in 2002. However, no assessments of lead exposure in Australian waterfowl have been published since the 1990s. Our aim was to estimate contemporary lead exposure via measuring bone lead concentrations in a harvested dabbling duck, the Pacific black duck (Anas superciliosa). We collected wings from 77 Pacific black ducks, spanning 2018 (n = 30) and 2021 (n = 47), from nine sites with long-term histories of regular waterfowl hunting. We sought to validate portable X-ray fluorescence (XRF) for this purpose by taking a piece of humerus bone from each bird, and measuring lead concentration (mg/kg), first via non-destructive XRF and then via destructive inductively coupled plasma mass spectrometry (ICP-MS) and validated the relationship via regression analysis. Portable XRF bone lead measurement demonstrated a strong correlation with ICP-MS results using root-transformed regression (R2 = 0.85). Greater than 92 % of ducks had only background lead exposure (<10 mg/kg). When compared to historical studies in the same species at similar field sites from the 1990s, lead exposure levels were considerably lower, with mean lead concentrations ∼2-fold lower (3.7 c.f. 7.7 mg/kg), and the frequency of birds with severe lead exposure (>20 mg/kg) ∼3-fold lower (2.6 c.f. 7.5 %). Our results confirm that portable XRF is a useful option for measurement of bone lead in Australasian waterbird species. Our findings also demonstrate that a ban on the use of lead shot around 20 years ago has been associated with a substantial reduction in lead exposure in at least one species of waterfowl.

Experimental dissolution of fossil bone under variable pH conditions.

Fossils exposed at the surface are an integral component of the paleontologic record and provide an archive of past life. However, it is widely known that fossils are not stable indefinitely upon exposure to surface conditions such as physical, chemical, and biological processes, and this last phase of taphonomy is poorly understood. Studies regarding the longevity of fossils subject to weathering, such as acidic precipitation, are absent in the literature. The goal of this study was to experimentally determine vertebrate fossil dissolution rates under variable pH conditions in a controlled laboratory setting. It was hypothesized that fossils would dissolve within acidic solutions and do so at an increasing rate when exposed to increasingly acidic solutions. The experiments were conducted on three fossil vertebrae in triplicate in closed reaction vessels at pH 4, 5, and 6. The fossils were completely submerged for 21 days in a tap water solution with the pH adjusted using 0.1N hydrochloric acid (HCl). Fossil dissolution was quantified by changes to: (1) fossil mass; (2) elemental chemistry of water and fossils with inductively coupled plasma mass spectrometry (ICP-MS); (3) fossil mineralogy with X-ray diffraction (XRD); and (4) histologic structures with thin section analyses. All fossils exhibited mass loss, which increased with decreasing pH conditions, and was greatest under pH 4 (477 to 803 mg loss). The elemental analyses with ICP-MS indicated an increase of both calcium (maximum increase of 315 ppm) and phosphorus (increase of 18 ppm) in aqueous solutions with increasing pH and a loss of those same elements from the fossils (maximum loss of 10 ppm Ca and 6 ppm P). XRD revealed loss of gypsum in all post-dissolution samples. Taken together, the results of ICP-MS and XRD suggest dissolution of the primary mineral phases, including hydroxylapatite, and secondary phases, particularly calcite and gypsum, resulting in an estimated mass loss at pH 4 of 23 to 28 mg per day. Thin section analysis showed degradation of both cortical and trabecular bone in all post-dissolution images, demonstrating physical changes to the fossils as a result of water-rock interactions. These findings constitute the first quantitative analysis of fossil dissolution rates and provide insights into this last stage of taphonomy, addressing a largely understudied potential bias in the vertebrate fossil record.

Combining microwave and ultraviolet energy for sample preparation of polymer-based materials for further halogen determination

In this work, a microwave-assisted ultraviolet wet digestion (MAWD-UV) protocol was used to digest polymer-based materials (e-waste, food packing, medical-care materials, and individual protection equipment) for further halogen determination. Digests were suitable for Cl, Br, and I determination by inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma optical emission spectrometry (ICP-OES). Fluorine determination was performed with ion selective electrode (ISE). The power radiation and the digestion solution were evaluated. The accuracy was evaluated by comparing the results with those obtained after neutron activation analysis (NAA) for Cl and Br or using microwave-induced combustion (MIC) as sample preparation for F and I. Two certified reference materials (CRM) of low-density polyethylene (ERM EC680k and EC681k) were evaluated, and no differences were observed (t-test, 95% confidence level) between the results and the certified values. Quantitative recoveries for Cl, Br, and I were obtained using 200 mg of the sample using diluted acid solution (15 mL of 0.5 mol L−1 HNO3 plus 10.6 mol L−1 of H2O2), with a 40 min radiation program (700 W, 25 min ramp). No statistical differences (ANOVA, 95% confidence level) were observed between the MAWD-UV and ICP-MS results and the reference values for Cl, Br, and I for several samples. However, results were lower than the reference values for fluorine, indicating that digestion efficiency was poor for this analyte, which was probably as an organic molecule (likely polytetrafluoroethylene). The limit of quantification (LOQ) was 0.216 mg g−1 for Cl, 3.33 µg g−1 for Br, and 0.036 µg g−1 for I using ICP-MS. The main advantage of MAWD-UV is that it enables decomposing several polymer-based matrices using diluted acid without halogen losses. The developed method represents an important contribution to the digestion of these hard-to-digest matrices and in compliance with green analytical chemistry, thereby being an advance in sample preparation.

Evidence of human impact in Antarctic region by studying atmospheric aerosols

Air quality is a global concerning topic because of its great impact on the environment and health. Because of that, the study of atmospheric aerosols looking for harmful pollutants is rising, as well as the interest in the origin of the contaminants. Depending on the nature and size of the aerosols, some elements can be detected at a great distance from the emission source, even in Antarctica, where this study is conducted. Several samples of PM filters from 2018 to 2019 (Deception Island) and 2019–2020 (Livingston Island) campaigns have been analyzed by three powerful spectroscopic techniques: FESEM (Field Emission Scanning Electron Microscopy), LIBS (Laser Induced Breakdown Spectroscopy), and ICP-MS (Inductively Coupled Plasma Mass Spectrometry). These techniques have allowed us to find some heavy metals in the air of the Antarctic region (Al, Fe, Ti, Ni, Cr, and Mn). Deeper studies on ICP-MS results have confirmed those results and have also provided information on their potential sources. Thus, while Al, Fe, Ti and Mn concentrations can be explained by crustal origin, Ni and Cr presented high values only coherent with important human contribution. The results point out that the Antarctic region is no longer a clean and isolated environment from human pollution.

Influence of Acidic Environment on Hydrolytic Stability of MDP-Ca Salts with Nanolayered and Amorphous Structures.

PurposeThis study aimed to investigate the hydrolytic stability of 10-methacryloyloxydecyl dihydrogen phosphate calcium (MDP-Ca) salts with nanolayered and amorphous structures in different pH environments.MethodsThe MDP-Ca salts were synthesized from MDP and calcium chloride and characterized by X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM). Inductively coupled plasma-mass spectrometry (ICP-MS) was used to quantify the release of calcium from the synthesized MDP-Ca salt, MDP-treated hydroxyapatite (MDP-HAp), and untreated HAp after soaking in acidic and neutral solutions for 1, 7, and 30 days. To study the hydrolytic process, we carried out molecular dynamics (MD) simulations of the nanolayered MCS-MD (monocalcium salt of the MDP dimer) and DCS-MD (dicalcium salt of the MDP dimer) structures, as well as of the amorphous-phase MCS-MM (monocalcium salt of the MDP monomer).ResultsThe TEM images showed that the nanolayered structures were partially degraded by acid attack. Based on the ICP-MS results, the hydrolysis rate of the MDP-Ca salt in acidic and neutral environments followed the order HAp > MDP-HAp > MDP-Ca salt. The MD simulations showed that, in acidic environments, clusters of MDP remained aggregated and all Ca2+ ions separated from the MDP monomer to interact with water molecules in aqueous solution. In neutral environments, Ca2+ ions always interacted with phosphate groups, OH− ions, and water molecules to form clusters centered on Ca2+ ions.ConclusionMDP-Ca presented higher hydrolysis rates in acidic than neutral environments. Nanolayered MCS-MD possessed the highest resistance to acidic hydrolysis, followed by amorphous MCS-MM and DCS-MD.

Health Hazards Assessment and Geochemistry of ElSibai-Abu ElTiyur Granites, Central Eastern Desert, Egypt

In this paper, a thorough radio- and chem-ecological evaluation of ElSibai-Abu ElTiyur granites located within Egypt’s crystalline basement rocks was conducted for risk and dose assessments. Twenty granitic samples from the study area’s various lithological units were analyzed using high-resolution γ-ray spectrometry to determine the natural radioisotopes (U-238, Th-232, and K-40) concentrations. The average concentrations of U-238, Th-232, and K-40 were 38.72, 38.23, and 860.71 Bq/kg, respectively, exceeding the GAV (global average value) documented by UNSCEAR (Scientific Committee on the Effects of Atomic Radiation, Vienna, Austria). The radiological parameters and indices judging the usage of ElSibai-Abu ElTiyur granites in homes were computed. The obtained results showed that ElSibai-Abu ElTiyur granites are safe to be used by inhabitants as superficial building materials, as per the globally accepted values and the recommended safety limits approved by UNSEAR, WHO (World Health Organization, Geneva, Switzerland), ICRP (International Commission on Radiological Protection, Ottawa, ON, Canada), and EC (European Commission, Luxembourg). Further, the samples were subjected to ICP-MS (inductively coupled plasma mass spectrometry) analysis for quantifying radionuclide variations with chemical composition. Geochemically based on the ICP-MS results, the studied granites proved to be highly evolved A-type granites. They span the metaluminous to peralkaline fields. The REE patterns are characterized by the enrichment of the light rare earths (LREE) over the heavy ones (HREE) where (La/Yb)n = 5.2, (Gd/Yb)n = 1.63 with pronounced negative Eu-anomalies (Eu/Eu*)n = 0.49. The albite granite exhibits the highest concentrations of Ga, Nb, Ta, U, and Y, and REE (Gd, Dy, Ho, Yb) than the Na-metasomatic granites. Finally, the obtained data serve as a valuable future database for finding out the compatibility of the geochemical data with the natural radioactivity levels of granites.

Portable X-ray fluorescence for bone lead measurements of Australian eagles

Lead (Pb) toxicity from ammunition has been shown to be a threat to scavenging birds across the globe. Toxic levels of lead have recently been found in Australia's largest bird of prey, the wedge-tailed eagle (Aquila audax), through inductively coupled plasma mass spectrometry (ICP-MS) analysis of liver and bone samples. However, ICP-MS is consumptive (causing damage to archived specimens), time-consuming, and expensive. For these reasons, portable X-ray fluorescence (XRF) devices have been optimized to measure bone lead in North American avian species, humans, and other environmental samples. In this study, we assessed portable XRF for bone lead measurement in Australian raptors in two parts. First, we validated the method using tissues from wedge-tailed eagles from Tasmania (A. a. fleayi), analysing bone samples taken from sites on the femur immediately adjacent to sites for which we had ICP-MS data (n = 89). Second, we measured lead via portable XRF in the skulls of wedge-tailed eagles from south-eastern mainland Australia (A. a. audax) collected during a criminal prosecution (n = 92). Portable XRF bone lead measurement demonstrated an excellent correlation with ICP-MS results using root-transformed regression (R2 = 0.88). Calculated equivalent ICP-MS values revealed that greater than 50% of the eagles from mainland Australia had elevated lead levels (>10 mg/kg) and 13% had severe lead exposure (>20 mg/kg). Our results support previous studies of North American avian species and suggest that portable XRF could be a useful and inexpensive option for measurement of bone lead in Australian scavenger species.

Ruthenium Removal Using Silica-Supported Aromatic Isocyanides

New silica gel scavengers containing aromatic isocyanides have been synthesized and evaluated for Ru removal. A thiol-ene click reaction was used to attach the isocyanide precursor to a thiol-containing siloxane. Conventional methods for grafting to silica gel at elevated temperature resulted in significant hydrolysis of the isocyanide. A novel cleavage reaction was developed to quantitate the amount of surface-loaded isocyanide. Binding by the new materials was comparatively evaluated for a variety or Ru carbene catalysts. The optimal conditions were extended to two ring-closing metatheses (RCM). The residual Ru was determined by inductively coupled plasma mass spectrometry (ICP-MS). For facile RCM reactions, the UV data agreed with the ICP-MS results. However, more difficult RCM did not correlate well with the UV data. This was interpreted in terms of varying extent of catalyst decomposition. In all cases, isocyanide scavenger reagents were found to be superior to commonly used, silica gel-based metal scavengers.

Determination of Nickel, Zinc and Cobalt in Advanced Materials Based on NixCo3 –xO4 and ZnxCo3 –xO4 by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-Ray Fluorescence

An approach to analysis of advanced sensor materials based on cobalt oxide modified with zinc or nickel oxides is developed using X-ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). It is shown that determination of Ni, Zn, and Co in novel materials based on cobalt oxide using ICP-MS in solutions is possible, the standard deviation being 0.06, 0.06, and 0.05, respectively. The results of the ICP-MS determination of the elements in solutions are used to certify the results obtained by the XRF method without sample preparation. It is shown that NixCo3 –xO4 – δ samples can be correctly analyzed without decomposition using X-ray fluorescence analysis. The results of the determination match theoretically calculated values for the samples obtained both from nitrates and from oxalates of nickel and cobalt. However, calibration based on the ICP-MS results is necessary for X-ray fluorescence analysis of ZnxCo3 –xO4 samples. It is shown that the zinc content in the samples exceeds the theoretical determined value by 10–30% because of incomplete precipitation of cobalt from the solution upon synthesis.

The capability of nonlinear optical characteristics as a predictor for cellular uptake of nanoparticles and cell damage.

Current methods for determining the cellular effects of a treatment modality need expensive materials and much time to provide a researcher with results. The aim of this study was to evaluate the potential of nonlinear optical characteristics of cancer cells using Z-scan technique to monitor the level of cellular uptake and cell damage caused by a nanotechnology based treatment modality. Two nanocomplexes were synthesized and characterized. The first one was made of alginate hydrogel co-loaded with cisplatin and gold nanoparticles (AuNPs) named as ACA nanocomplex. The second one, named as AA nanocomplex, was the same as ACA, but without cisplatin and this AA nanocomplex was considered as the control for ACA. Different groups of CT26 mouse colon cancer cell line received various treatments of cisplatin, ACA, and AA nanocomplexes and then the samples were prepared for Z-scan studies. The MTT assay was used to evaluate the cytotoxicity induced by different treatment modalities. Transmission electron microscopy (TEM) and inductively coupled plasma-mass spectrometry (ICP-MS) were used for qualitative and quantitative assessments of the level of AuNPs cellular uptake. The trend of nonlinear optical properties changes for treated cells was in agreement with MTT, TEM and ICP-MS results. Z-scan technique was able to successfully indicate the occurrence of cell damage. It was also capable to determine the intensity of cell damage induced by ACA nanocomplex in comparison to free cisplatin. Furthermore, Z-scan results showed that it was able to discriminate the differences of optical properties of the cells incubated with ACA nanocomplex for various incubation times. Nonlinear optical characteristics of a cell may be considered as a reliable indicator to predict the level of cellular effects induced by a nanotechnology based treatment modality. The protocol suggested in this article does not waste materials, not take much time to provide the results, and it is inexpensive technique.

Rapid and efficient removal of silver nanoparticles from plant surfaces using sodium hypochlorite and ammonium hydroxide solution

With the increasing likelihood of significant release of engineered nanomaterials (ENMs) into the environment, investigations focused on the behavior and impact of ENMs on plant species which have become more important and prevalent. One consistent challenge in these studies is how to separate the plant surface-attached and internalized ENMs. Unfortunately, there are no current effective methods to remove ENMs from plant surfaces. In this study, a protocol was developed to remove surface-attached silver nanoparticles (AgNPs) from spinach leaves. Spinach leaves were exposed to three kinds of AgNPs (2 μg per leaf) for 1 h and 7-day foliar exposure times, including 40 nm CIT- and PVP-AgNPs, and 100 nm CIT-AgNPs. Harvested AgNPs-contaminated spinach leaves were sequentially immersed in solutions of Clorox bleach (sodium hypochlorite, 200 mg/L, 5 min) and ammonium hydroxide (NH3·H2O, 2.8%, 1 min), with a final rinse in deionized (DI) water (1 min). The AgNPs removal efficiency was evaluated by inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy (SEM). Both ICP-MS results and SEM images demonstrated effective removal of 91–93% of the surface-attached Ag residuals from the contaminated spinach leaves. This value was significantly higher than removal with DI water (7%), Clorox bleach alone (36%), or NH3·H2O alone (36%). However, no significant changes were observed for the internalized AgNPs, indicating that this method is only surface active. This study provides essential information for the rapid and efficient removal of surface-attached AgNPs and furthers understanding of NP interactions with food crops. Importantly, all chemicals used in this developed washing protocol are generally considered as safe (GRAS), and could readily be used as a postharvest washing procedure to reduce Ag contaminants in leafy vegetables.

DETERMINATION OF NICKEL, ZINC AND COBALT IN ADVANCED MATERIALS BASED ON NixCo3–xO4 AND ZnxCo3–xO4 BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY (ICP-MS) AND X-RAY FLUORESCENCE

An approach to analysis of advanced sensor materials based on cobalt oxide modified with zinc or nickel oxides is developed using X- ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). It is shown that determination of Ni, Zn and Co in novel materials based on cobalt oxide using ICP-MS in solutions is possible, standard deviation being 0.06, 0.06, and 0.05, respectively. The results of the ICP-MS determination of the elements in solutions are used to certify the results obtained by XRF method without sample preparation. It is shown that NixCo3–xO4–д samples can be correctly analyzed without decomposition using X- ray fluorescence analysis. The results of the determination match theoretically calculated values both for the samples obtained from nitrates and from nickel and cobalt oxalates as well. However, calibration based on the ICP-MS results is necessary for X-ray fluorescence analysis of ZnxCo3–xO4 samples. It is shown that zinc content in the samples exceeds the theoretical determined value by 10 – 30% due to incomplete precipitation of cobalt from the solution upon synthesis.

Feasibility of a portable X-ray fluorescence device for bone lead measurements of condor bones

Lead based ammunition is a primary source of lead exposure, especially for scavenging wildlife. Lead poisoning remains the leading cause of diagnosed death for the critically endangered California condors, which are annually monitored via blood tests for lead exposure. The results of these tests are helpful in determining recent exposure in condors and in defining the potential for exposure to other species including humans. Since condors are victim to acute and chronic lead exposure, being able to measure both would lend valuable information on the rates of exposure and accumulation through time. A commercial portable X-ray fluorescence (XRF) device has been optimized to measure bone lead in vivo in humans, but this device could also be valuable for field measurements of bone lead in avian species. In this study, we performed measurements of bone Pb in excised, bare condor bones using inductively coupled plasma mass spectrometry (ICP-MS), a cadmium 109 (Cd-109) K-shell X-ray fluorescence (KXRF) system, and a portable XRF system. Both KXRF and portable XRF bone Pb measurement techniques demonstrated good correlations with ICP-MS results (r=0.93 and r=0.92 respectively), even with increasing skin thickness (r=0.86 between ICP-MS and portable XRF at 1.54mm of soft tissue). In conclusion, our results suggest that a portable XRF could be a useful option for measurement of bone Pb in avian species in the field.

Quantification of impurities in carbon nanotubes: Development of ICP-MS sample preparation methods

Carbon nanotubes (CNTs) are one of the prospective nanomaterials to be used in consumer products. Commercially available carbon nanotubes contain significant amounts of metal impurities which are added during synthesis as a catalyst. The presence of metal impurities in CNTs influences the physicochemical properties of materials and its applications. The quantification of metal impurities in CNTs is essential to conduct environmental and health risk assessments. This study aims to develop a method which can be used effectively in laboratories to quantify multi-element impurities in CNTs using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Prior to the analysis, samples were prepared by conventional microwave acid digestion (CMAD) and microwave oxygen combustion (MOC). In addition, the ICP-MS method was validated by determining multiple analytical figures of merit such as linear calibration range, system suitability, method detection limit (MDL), limit of quantitation (LOQ), and accuracy. The developed CMAD and MOC methods were suitable to digest metal impurities in carbon nanotubes and the ICP-MS results were in good agreement (80–110% of recovery) with the certified values. In comparison of two methods, CMAD is a simple and straightforward two-step procedure with safe experimental conditions, and requires only 5 mg of sample. Moreover, CMAD overcomes the disadvantage of the pre-existing CNT digestion methods such as the requirement of multi-step acid digestion and drying processes.

Gunshot residues (GSR) analysis of clean range ammunition using SEM/EDX, colorimetric test and ICP-MS: A comparative approach between the analytical techniques

Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool for a rapid analysis of chemical elements due to its high sensitivity, selectivity and multi-elemental character. Herein, the ability of the ICP-MS technique is evaluated to determine the gunshot residues (GSR) from clean range ammunition using a 0.40 caliber pistol and a 0.38 caliber revolver as a function of number of shots (n=1–7 shots for the pistol and n=1–5 shots for the revolver). The GSR was collected on the two regions of right and left hands: thumb and forefinger palm and thumb and forefinger back. ICP-MS results were compared to classical techniques in the forensic ballistics: the colorimetric test using sodium rhodizonate reagent and scanning electron microscope with energy dispersive X-ray spectrometry (SEM/EDX). Negative results were found for Pb and Ba using the colorimetric test from GSR with n=7 shots from 0.40 caliber pistol. For SEM/EDX analysis, photomicrographs show indefinite morphology for the GSR of clean range ammunition, in contrast to reported by conventional GSR. Moreover, the EDX results primarily identified C, O, K, Al, S, Si, Cu, Zn, Ti, Cr, Cl, Mo, Sr, and Fe. Differently, ICP-MS provided positive results for Pb, Ba and Sb, with maximum concentrations of 4.20μg·L−1, 10.9μg·L−1 and 0.119μg·L−1, respectively, as well as for Al, Ti, Cr, Mo, Cu, Zn and Sr. Finally, Al, Zn, Cu and Sr can be used as new markers of GSR of clean range ammunition, since they are the most abundant species detected.

Preparation of silicon-modified antimicrobial polyethylene endotracheal tubes.

Antimicrobial coating of polyethylene endotracheal tubes (PE ETTs) has proven to be an effective method to prevent endoluminal biofilm formation. A transparent silicon-modified antimicrobial PE ETT was obtained by coating PE with a SiO2 /γ-methacryloxypropyl trimethoxy silane (KH-570)/methyltriethoxysilane (MTES)/Ag-SiO2 solution prepared by chemically mixing Ag-SiO2 with SiO2 /KH-570/MTES in solution via a dip-coating method, with tetraethyl orthosilicate (TEOS) as the inorganic silicon source, followed by drying. All the films were characterized by various techniques, including the pencil hardness test, infrared spectroscopy, scanning electron microscopy, UV-vis analysis, and inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the TEOS/KH-570/MTES/Ag-SiO2 (15:6:1:0.6-1.0) films, which exhibited simple in-solution film formation on PE ETTs, had a homogeneous morphology, high transmittance above 87%, high hardness of 5H and strong adhesion to the tubes. The concentration of Ag+ ion dissolved out from the antibacterial coating is very low in ICP-MS results. The antibacterial test results show that the antibacterial coatings have excellent antibacterial property with antibacterial ratio up to 93.5% when Ag-SiO2 content is 2.6%. In pyrogen test and hemolytic test, the body temperature of rabbits rise 0.03°c for 3 h after inserting antibacterial PE ETT, and the hemolytic ratio is 0.7512%, which conform to the requirements of biomedical material. The results preliminarily proved that the antibacterial materials could be a good candidate of medical catheter material application or medical device surface coating materials. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 91-98, 2017.

Flow system, physical properties and heavy metals concentration of groundwater: A case study of an area within a municipal landfill site

Groundwater within the Olusosun landfill site in Lagos Metropolis was evaluated. Previous research on quality parameters of groundwater in the area made use of equipment of low detection capacity for heavy metals concentrations in water. Also, subsurface flow and significant attenuation of leachate due to horizontal distance between wells and landfill site are yet to be technically elucidated. In the present investigation, priority was given to heavy metals as small quantities may build up in human systems to become a significant health hazard. Then analysis was done with Inductively Coupled Plasma Mass Spectrometry (ICP-MS), while Geographical Information Systems (GIS) technique was used for spatial data analysis and management to illustrate localised flow of groundwater. Digital subsurface model of data from 20 drinking-water wells showed that flow directions are north-south, north-west and south-east. The two extremes of the pH for the groundwater are 4.04 and 8.05, indicating slightly acidic to weakly basic water. Total Dissolved Solids (TDS) are positively-strongly correlated with electrical conductivity (EC) in a line of fit TDS = 29.71 EC - 47.9. From the ICP-MS results, Fe concentrations at locations 1, 3 and 4, and Pb concentrations at locations 1, 5, 7, 8, 14 and 16 did not conform to international human-health benchmarks. Generally, the longer the horizontal distance between a well and the landfill site, the lesser its potential for groundwater contamination. This study better clarifies heavy metals concentrations in water, with GIS for satisfactorily display of positional and attribute for groundwater flow in the area. Key words: Heavy metals, groundwater, landfill, Geographical Information Systems (GIS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

Determination of mercury in phosphate fertilizers by cold vapor atomic absorption spectrometry

In this paper, a method for the determination of mercury in phosphate fertilizers using slurry sampling and cold vapor atomic absorption spectrometry (CV QT AAS) is proposed. Because mercury (II) ions form strong complexes with phosphor compounds, the formation of metallic mercury vapor requires the presence of lanthanum chloride as a release agent. Thiourea increases the amount of mercury that is extracted from the solid sample to the liquid phase of the slurry. The method is established using two steps. First, the slurry is prepared using the sample, lanthanum chloride, hydrochloric acid solution and thiourea solution and is sonicated for 20min. Afterward, mercury vapor is generated using an aliquot of the slurry in the presence of the hydrochloric acid solution and isoamylic alcohol with sodium tetrahydroborate solution as the reducing agent. The experimental conditions for slurry preparation were optimized using two-level full factorial design involving the factors: thiourea and lanthanum chloride concentrations and the duration of sonication.The method allows the determination of mercury by external calibration using aqueous standards with limits of detection and quantification of 2.4 and 8.2μgkg−1, respectively, and precision, expressed as relative standard deviation, of 6.36 and 5.81% for two phosphate fertilizer samples with mercury concentrations of 0.24 and 0.57mgkg−1, respectively. The accuracy was confirmed by the analysis of a certified reference material of phosphate fertilizer that was provided by the National Institute of Standards & Technology (NIST). The method was applied to determine mercury in six commercial samples of phosphate fertilizers. The mercury content varied from 33.97 to 209.28μgkg−1. These samples were also analyzed employing inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS results were consistent with the results from our proposed method.

Pilot estuarine mesocosm study on the environmental fate of Silver nanomaterials leached from consumer products

Although nanosilver consumer products (CPs) enjoy widespread availability, the environmental fate, leaching, and bioaccumulation behaviors of silver nanoparticles (AgNPs) from these products are not well understood. In this work, three nanosilver CPs, two AgNP standards, and an ionic silver (Ag+) standard were studied in estuarine mesocosms. The CPs exhibited long-term release of significant amounts of silver over a 60d residence time in the mesocosms, and ultimately released 82 - 99% of their total silver loads. Measurements of total silver as a function of time, by inductively coupled plasma mass spectrometry (ICP-MS), indicated that the silver was transferred from the water column and accumulated in the estuarine biota, including hard clams, grass shrimp, mud snails, cordgrass stalks and leaves, biofilms, intertidal sediment, and sand. The ICP-MS results and calculations of bioconcentration and trophic transfer factors indicated that significant amounts of silver were taken up by the organisms through trophic transfer. Silver was also adsorbed from the seawater into the biofilms, sediment, and sand, and from the sand into the clams.

Function of mesenchymal stem cells following loading of gold nanotracers

Background:Stem cells can differentiate into multiple cell types, and therefore can be used for cellular therapies, including tissue repair. However, the participation of stem cells in tissue repair and neovascularization is not well understood. Therefore, implementing a noninvasive, long-term imaging technique to track stem cells in vivo is needed to obtain a better understanding of the wound healing response. Generally, we are interested in developing an imaging approach to track mesenchymal stem cells (MSCs) in vivo after delivery via a polyethylene glycol modified fibrin matrix (PEGylated fibrin matrix) using MSCs loaded with gold nanoparticles as nanotracers. The objective of the current study was to assess the effects of loading MSCs with gold nanoparticles on cellular function.Methods:In this study, we utilized various gold nanoparticle formulations by varying size and surface coatings and assessed the efficiency of cell labeling using darkfield microscopy. We hypothesized that loading cells with gold nanotracers would not significantly alter cell function due to the inert and biocompatible characteristics of gold. The effect of nanoparticle loading on cell viability and cytotoxicity was analyzed using a LIVE/DEAD stain and an MTT assay. The ability of MSCs to differentiate into adipocytes and osteocytes after nanoparticle loading was also examined. In addition, nanoparticle loading and retention over time was assessed using inductively coupled plasma mass spectrometry (ICP-MS).Conclusion:Our results demonstrate that loading MSCs with gold nanotracers does not alter cell function and, based on the ICP-MS results, long-term imaging and tracking of MSCs is feasible. These findings strengthen the possibility of imaging MSCs in vivo, such as with optical or photoacoustic imaging, to understand better the participation and role of MSCs in neovascularization.