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  • 1
    Language: English
    In: Analytical chemistry, 15 May 2012, Vol.84(10), pp.4340-9
    Description: A new two-step extraction procedure is proposed for separation and preconcentration of gold nanoparticles (Au-NPs) from aqueous samples. First, Au-NPs are loaded onto a reversed phase C-18 (RP-C18) column, and then ligand-assisted extraction into chloroform is performed. 1-Dodecanethiol (1-DDT, 5 mM) was used as selective ligand for quantitative extraction under ultrasonic condition. Parameters of the extraction procedure, such as sample volume, organic solvent, concentration and nature of the ligand, ultrasonication time, pH of the sample, and different coating as well as sizes of Au-NPs were investigated in regard to the extraction efficiency of Au-NPs. The optimized procedure allows separation and preconcentration of the Au-NPs with an enrichment factor of up to 250 assuring no changes in size and/or shape of the NPs. This was proved by investigation of the particles by UV-vis spectrometry and transmission electron microscopy (TEM). Furthermore, the presence of potentially interfering other metal nanoparticles (M-NPs) and dissolved organic matter (DOM) was studied. Observed minor recoveries of Au-NPs in DOM model solutions were overcome by hydrogen peroxide pretreatment up to a DOM concentration of about 4 mg/L. Feasibility of the proposed method was proved by application of the optimized procedure to 5 real water samples. Recoveries of Au-NPs in the real waters spiked in a concentration range from 0.15 to 5100 μg/L obtained by this method varied from 68.4% to 99.4%. Consequently, the proposed approach has great potential for the analysis of M-NPs in environmental waters.
    Keywords: Ligands ; Nanoparticles ; Gold ; Extraction Processes ; Water ; Analytical Chemistry;
    ISSN: 00032700
    E-ISSN: 1520-6882
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  • 2
    In: Chemical Communications, 2012, Vol.48(73), pp.9165-9167
    Description: Capable of preserving the size and shape of nanoparticles, a novel method to effectively and selectively extract noble metal nanoparticles even at the 80 ng L 1 level from real environmental water was designed and performed using a noncovalent reversible adsorption onto an ionic exchange resin.
    Keywords: Adsorption ; Extraction ; Nanoparticles ; Noble Metals ; Polymers ; Preserving ; Resins ; Miscellaneous Sciences (So) ; Components and Materials (General) (Ea);
    ISSN: 1359-7345
    E-ISSN: 1364-548X
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  • 3
    Language: English
    In: Science of the Total Environment, 01 April 2017, Vol.583, pp.169-175
    Description: Roadside dust and soil samples were collected at different sites in the area of Ulm and Munich in Germany. Road dust samples were collected in tunnels where the traffic-related dust is less influenced by atmospheric conditions. Soil samples were taken with a drill bar at varying distances to motorways, district and regional roads with different traffic densities. The soil cylinders of 30 cm length were divided into four sections in order to obtain depth profiles for palladium (Pd) distribution. Determination of Pd in total digests of the samples was performed by ligand-assisted selective separation and preconcentration of Pd(II) using solid phase extraction followed by high-resolution continuum source graphite furnace spectrometry. The analytical procedure was successfully validated using the certified reference material and by recovery experiments in spiked soil samples. The average Pd concentration found in the road dusts was 311 μg kg , the maximum Pd concentration in the topsoil layer was 193 μg kg . Pd depth profiles reveal transportation of Pd into deeper soil layers, where even at a depth of 25 to 30 cm a Pd concentration of 19 μg kg was found, proving the high mobility of Pd. Different factors like traffic density and age of the soils are discussed in the context of the found Pd depth profiles.
    Keywords: Traffic-Related Palladium Emission ; Roadside Soil ; Pd Depth Profiles ; Migration of Palladium ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 4
    Language: English
    In: Environmental Pollution, November 2018, Vol.242, pp.1119-1127
    Description: The aim of this study was to evaluate the mobility of platinum (Pt) and palladium (Pd) emissions from automotive catalysts in soils and to contribute to the risk assessment of platinum group metals (PGMs) discharged from catalysts in the environment. To address this question, for the first time risk assessment code (RAC) was applied to consider the results from sequential extraction of different Pd and Pt species from soils. For this purpose, model soil samples were prepared spiking defined Pd or Pt species, respectively, at known concentrations. In order to mimic emitted species as well as possible transformation products of traffic-related Pd and Pt emissions in soils, coated and uncoated elemental nanoparticles (cPd/cPt NPs, Pd/Pt NPs) and ionic divalent metal species (Pd(II)/Pt(II)) were applied. All model samples were characterized in detail and the developed sequential extraction scheme was validated. RAC values ranged between 24 and 8% revealing medium to low risk. The order of mobility for the studied species was found to be Pt(II) 〉 cPd NPs » Pd(II) 〉 Pd NPs 〉 Pt NPs 〉 cPt NPs. Furthermore, migration of Pd species in gravity columns was studied confirming highest transport of cPd NPs. Mobility of traffic-related Pd and Pt emissions in soils depends on their species and evaluation by risk assessment code gives values ranging from 8 to 24%, hence medium risk potentials.
    Keywords: Platinum Group Metals (Pgm) ; Car Exhaust Emissions ; Sequential Extraction ; Mobility in Soils ; Risk Assessment Code ; Migration of Pgm in Soils ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 5
    Language: English
    In: Journal of Colloid And Interface Science, 01 May 2013, Vol.397, pp.199-205
    Description: ► A ligand-assisted phase transfer was used to transfer Au-NPs from an aqueous solution to -hexane. ► 1-Dodecanethiol (DDT) was the most efficient ligand with the highest transfer efficiency (〉96%). ► DDT-assisted phase transfer can preserve the shape and size of Au-NPs during the phase transfer. ► The transfer efficiency is dependent on the molar ratio of ligand to Au-NPs. ► The transfer index is a parameter to evaluate the transfer efficiency. An efficient ligand-assisted phase transfer method has been developed to transfer gold nanoparticles (Au-NPs, : 5–25 nm) from an aqueous solution to -hexane. Four different ligands, namely 1-dodecanethiol (DDT), 1-octadecanethiol (ODT), dodecylamine (DDA), and octadecylamine (ODA) were investigated, and DDT was found to be the most efficient ligand. It appears that the molar ratio of DDT to Au-NPs is a critical factor affecting the transfer efficiency, and 270–310 is found to be the optimum range, under which the transfer efficiency is 〉96%. Moreover, the DDT-assisted phase transfer can preserve the shape and size of the Au-NPs, which was confirmed by UV–vis spectra and transmission electron microscopy (TEM). Additionally, the transferred Au-NPs still can be well dispersed in the -hexane phase and remain stable for at least 2 weeks. On the other hand, the ODT-, DDA-, and ODA-assisted phase transfer is fraught with problems either related to transfer efficiency or NPs aggregation. Overall, the DDT-assisted phase transfer of Au-NPs provides a rapid and efficient method to recover Au-NPs from an aqueous solution to -hexane.
    Keywords: Gold Nanoparticles ; 1-Dodecanethiol ; 1-Octadecanethiol ; Dodecylamine ; Octadecylamine ; Phase Transfer ; Transfer Efficiency ; Transfer Index ; Engineering ; Chemistry
    ISSN: 0021-9797
    E-ISSN: 1095-7103
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  • 6
    Language: English
    In: Journal of colloid and interface science, 2013, Vol.397, pp.199-205
    Description: An efficient ligand-assisted phase transfer method has been developed to transfer gold nanoparticles (Au-NPs, d: 5–25nm) from an aqueous solution to n-hexane. Four different ligands, namely 1-dodecanethiol (DDT), 1-octadecanethiol (ODT), dodecylamine (DDA), and octadecylamine (ODA) were investigated, and DDT was found to be the most efficient ligand. It appears that the molar ratio of DDT to Au-NPs is a critical factor affecting the transfer efficiency, and 270–310 is found to be the optimum range, under which the transfer efficiency is 〉96%. Moreover, the DDT-assisted phase transfer can preserve the shape and size of the Au-NPs, which was confirmed by UV–vis spectra and transmission electron microscopy (TEM). Additionally, the transferred Au-NPs still can be well dispersed in the n-hexane phase and remain stable for at least 2weeks. On the other hand, the ODT-, DDA-, and ODA-assisted phase transfer is fraught with problems either related to transfer efficiency or NPs aggregation. Overall, the DDT-assisted phase transfer of Au-NPs provides a rapid and efficient method to recover Au-NPs from an aqueous solution to n-hexane. ; p. 199-205.
    Keywords: Transmission Electron Microscopy ; Nanogold ; Ligands ; Hexane ; Ddt (Pesticide) ; Aqueous Solutions
    ISSN: 0021-9797
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 7
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2014, Vol.406(16), pp.3887-3894
    Description: In this work, we present a fast and simple approach for detection of silver nanoparticles (AgNPs) in biological material (parsley) by solid sampling high-resolution–continuum source atomic absorption spectrometry (HR-CS AAS). A novel evaluation strategy was developed in order to distinguish AgNPs from ionic silver and for sizing of AgNPs. For this purpose, atomisation delay was introduced as significant indication of AgNPs, whereas atomisation rates allow distinction of 20-, 60-, and 80-nm AgNPs. Atomisation delays were found to be higher for samples containing silver ions than for samples containing silver nanoparticles. A maximum difference in atomisation delay normalised by the sample weight of 6.27 ± 0.96 s mg −1 was obtained after optimisation of the furnace program of the AAS. For this purpose, a multivariate experimental design was used varying atomisation temperature, atomisation heating rate and pyrolysis temperature. Atomisation rates were calculated as the slope of the first inflection point of the absorbance signals and correlated with the size of the AgNPs in the biological sample. Hence, solid sampling HR-CS AAS was proved to be a promising tool for identifying and distinguishing silver nanoparticles from ionic silver directly in solid biological samples. Figure Fast and simple approach for direct identification and sizing of silver nanoparticles in biological material (parsley) applying solid sampling high-resolution continuum source atomic absorption spectrometry and a novel data evaluation strategy
    Keywords: Silver nanoparticle detection ; High-resolution–continuum source atomic absorption spectrometry ; Solid sampling ; Food analysis
    ISSN: 1618-2642
    E-ISSN: 1618-2650
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  • 8
    Language: English
    In: Analytical and bioanalytical chemistry, June 2014, Vol.406(16), pp.3887-94
    Description: In this work, we present a fast and simple approach for detection of silver nanoparticles (AgNPs) in biological material (parsley) by solid sampling high-resolution-continuum source atomic absorption spectrometry (HR-CS AAS). A novel evaluation strategy was developed in order to distinguish AgNPs from ionic silver and for sizing of AgNPs. For this purpose, atomisation delay was introduced as significant indication of AgNPs, whereas atomisation rates allow distinction of 20-, 60-, and 80-nm AgNPs. Atomisation delays were found to be higher for samples containing silver ions than for samples containing silver nanoparticles. A maximum difference in atomisation delay normalised by the sample weight of 6.27 ± 0.96 s mg(-1) was obtained after optimisation of the furnace program of the AAS. For this purpose, a multivariate experimental design was used varying atomisation temperature, atomisation heating rate and pyrolysis temperature. Atomisation rates were calculated as the slope of the first inflection point of the absorbance signals and correlated with the size of the AgNPs in the biological sample. Hence, solid sampling HR-CS AAS was proved to be a promising tool for identifying and distinguishing silver nanoparticles from ionic silver directly in solid biological samples.
    Keywords: Food Contamination -- Analysis ; Metal Nanoparticles -- Chemistry ; Petroselinum -- Chemistry ; Silver -- Chemistry ; Spectrophotometry, Atomic -- Methods
    ISSN: 16182642
    E-ISSN: 1618-2650
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  • 9
    Language: English
    In: Analytical and Bioanalytical Chemistry, 2012, Vol.403(8), pp.2419-2428
    Description: A fully automated online ultraviolet (UV) digestion method for subsequent mercury (Hg) quantification in humic matter containing river waters is reported. The new developed flow injection analysis system (FIAS) consists basically of a UV lamp, a meander-form quartz glass reaction tube for online irradiation of the sample, and a nano-gold collector for preconcentration of dissolved mercury species. The FIAS is coupled to an atomic fluorescence spectrometer (AFS) for Hg detection. The optimized procedure allows accurate mercury quantification in water samples with up to 15 mg C L −1 as dissolved organic carbon by addition of only 1% ( v / v ) of hydrogen peroxide solution and online UV irradiation for 6 min. Addition of strong oxidants and any other reagents is avoided due to the use of the catalytic active nano-gold collector. Here, preconcentration of Hg species, release of mercury as Hg 0 , and AFS measurement are performed without addition of any reagents. Hence, the proposed approach offers significant advantages over existing methods. Analytical figures of merit showed the good performance of the developed method: The limit of quantification was found to be as low as 0.14 ng Hg L −1 . The linear working range is from 0.1 to 200 ng Hg L −1 and relative standard deviation is 〈6.0% ( n  = 9). The system was successfully validated by comparison of the mercury concentrations found in model and real water samples obtained by the reference method EPA 1631 and the proposed method. Furthermore, application to six real river waters confirmed the feasibility of the proposed approach. Figure Ultra-trace determination of mercury in river waters after online UV digestion of humic matter
    Keywords: Mercury trace analysis ; Natural waters ; Humic matter ; Online digestion ; HO-assisted UV digestion ; Preconcentration ; Nano-gold collector ; Flow injection analysis
    ISSN: 1618-2642
    E-ISSN: 1618-2650
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  • 10
    Language: English
    In: Analytica Chimica Acta, 2010, Vol.663(2), pp.127-138
    Description: This review summarises current knowledge on Hg species and their distribution in the hydrosphere and gives typical concentration ranges in open ocean, coastal and estuarine waters, as well as in rivers, lakes, rain and ground waters. The importance of reliable methods for the determination of Hg species in natural waters and the analytical challenges associated with them are discussed. Approaches for sample collection and storage, pre-concentration, separation, and detection are critically compared. The review covers well established methods for total mercury determination and identifies new approaches that offer advantages such as ease of use and reduced risk of contamination. Pre-concentration and separation techniques for Hg speciation are divided into chromatographic and non-chromatographic methods. Derivatisation methods and the coupling of pre-concentration and/or separation methods to suitable detection techniques are also discussed. Techniques for sample pre-treatment, pre-concentration, separation, and quantification of Hg species, together with examples of total Hg determination and Hg speciation analysis in different natural (non-spiked) waters are summarised in tables, with a focus on applications from the last decade.
    Keywords: Mercury Analysis ; Speciation ; Natural Waters ; Sample Storage ; Pre-Concentration ; Separation ; Chemistry
    ISSN: 0003-2670
    E-ISSN: 1873-4324
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