Chemische Charakterisierung und Spurenanalytik
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Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. An accurate separation, identification and characterization of nanoparticles becomes increasingly important.
A common method for nanoparticle separation, which was introduced in 1976 by Giddings, represents asymmetrical field-flow fractionation (AF4). It is a flow based separation method, which can be theoretically used to separate particles range from 1 nm to 50 µm. However, when the particles are smaller than 10 nm, separation with AF4 will become difficult to perform. Because in this case strong separation force, which induces aggregation of particles, should be applied. This will decrease recoveries of analytes and limit its application in accurate quantitative analysis. Capillary electrophoresis (CE) is another well-developed separation technique, in which samples will be separated in relation to their electrophoretic mobility. In recent years, CE has been used to separate different kinds of nanoparticles like, gold colloids or CdSe Quantum dots. However, till now only separation of particles smaller than 50 nm was reported. Because large size distribution of bigger particles will result in strong peak broadening and long separation time.
A two-dimensional coupling of AF4 and CE might provide us a new separation method, which can extend the separation ranges of both methods and be a way to characterise particles with large size distributions.
Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. An accurate separation, identification and characterization of nanoparticles becomes increasingly important.
A common method for nanoparticle separation, which was introduced in 1976 by Giddings, represents asymmetrical field-flow fractionation (AF4). It is a flow based separation method, which can be theoretically used to separate particles range from 1 nm to 50 µm. However, when the particles are smaller than 10 nm, separation with AF4 will become difficult to perform. Because in this case strong separation force, which induces aggregation of particles, should be applied. This will decrease recoveries of analytes and limit its application in accurate quantitative analysis. Capillary electrophoresis (CE) is another well-developed separation technique, in which samples will be separated in relation to their electrophoretic mobility. In recent years, CE has been used to separate different kinds of nanoparticles like, gold colloids or CdSe Quantum dots. However, till now only separation of particles smaller than 50 nm was reported. Because large size distribution of bigger particles will result in strong peak broadening and long separation time.
A two-dimensional coupling of AF4 and CE might provide us a new separation method, which can extend the separation ranges of both methods and be a way to characterise particles with large size distributions.
Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. An accurate separation, identification and characterization of nanoparticles becomes increasingly important1,2.
In this presentation, a two-dimensional separation approach based on AF4 and CE was showed and used to separate NPs with similar sizes but different coatings. Standard reference polystyrene NPs having comparable core sizes but different coatings were investigated. Different migration time and profiles were compared. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots in case of 20 and 50 nm particle mixtures, whereas the 100 nm NP mixture could not be separated. Various factors affecting the separation like hydrodynamic diameter or SDS concentration were discussed.
Future investigations will be focussed on inorganic NPs with differently charged coatings. There, AF4-CE coupling can be coupled with inductively coupled plasma mass spectrometry (ICP-MS) to enhance the sensitivity of this method.
The successful off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for Separation of nanoparticles (NPs) with different surface coatings was shown.
Two mixtures of polystyrene nanoparticles (PS-NPs) with comparable core sizes (20 nm and 50 nm) but different coatings (no coating/carboxyl-coated) were studied. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional off-line coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots and can obviouly improve separation resolution.
The successful off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for Separation of nanoparticles (NPs) with different surface coatings was shown.
Two mixtures of polystyrene nanoparticles (PS-NPs) with comparable core sizes (20 nm and 50 nm) but different coatings (no coating/carboxyl-coated) were studied. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional off-line coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots and can obviouly improve separation resolution.
Due to the fast growth of industry and the use of metal-containing compounds such as sewage sludge in agricultural fields, soil pollution associated with heavy metals presents a terrifying threat to the environment. Throughout the world, there are already 5 million sites of soil contaminated by heavy metals1. Some heavy metals pollutants can influence food chain safety and food quality, which in turn affects human health. According to the German Federal Soil Protection and Contaminated Site Ordinance (BBodSchV) 13 heavy metals such as arsenic (As), lead (Pb) and cadmium (Cd) are classified as heavily toxic to human health2. Therefore, elemental analysis and precise quantification of the heavy metals in soil are of great importance.
Inductively coupled plasma mass spectrometry (ICP-MS) emerged as a powerful technique for trace analysis of soil due to its multi-element capability, high sensitivity and low sample consumption. However, despite its success and widespread use, ICP-MS has several persistent drawbacks, such as high argon gas consumption, argon-based polyatomic interferences and the need for complicated RF-power generators. Unlike argon-based ICP, the nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) uses nitrogen as plasma gas, which eliminates high operating costs associated with argon-gas consumption as well as the argon-based interferences3. For the first time, the applicability of MICAP-MS for elemental analysis of environmental soils is investigated in this work. For this purpose, 7 reference- and 3 random soil samples containing vanadium (V), cobalt (Co), zink (Zn), copper (Cu), chrome (Cr), mercury (Hg), As, Pb and Cd are digested with aqua regia and used for analysis. Concentrations of selected elements are determined using MICAP-MS and validated using ICP-MS. Sensitivities, limits of detection and gas consumption for both methods are compared and discussed in detail. Moreover, the performance of MICAP-MS under different nitrogen plasma gas concentrations is investigated and compared
Due to the fast growth of industry and the use of metal-containing compounds such as sewage sludge in agricultural fields, soil pollution associated with heavy metals presents a terrifying threat to the environment. Throughout the world, there are already 5 million sites of soil contaminated by heavy metals1. Some heavy metals pollutants can influence food chain safety and food quality, which in turn affects human health. According to the German Federal Soil Protection and Contaminated Site Ordinance (BBodSchV) 13 heavy metals such as arsenic (As), lead (Pb) and cadmium (Cd) are classified as heavily toxic to human health2. Therefore, elemental analysis and precise quantification of the heavy metals in soil are of great importance.
Inductively coupled plasma mass spectrometry (ICP-MS) emerged as a powerful technique for trace analysis of soil due to its multi-element capability, high sensitivity and low sample consumption. However, despite its success and widespread use, ICP-MS has several persistent drawbacks, such as high argon gas consumption, argon-based polyatomic interferences and the need for complicated RF-power generators. Unlike argon-based ICP, the nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) uses nitrogen as plasma gas, which eliminates high operating costs associated with argon-gas consumption as well as the argon-based interferences3. For the first time, the applicability of MICAP-MS for elemental analysis of environmental soils is investigated in this work. For this purpose, 7 reference- and 3 random soil samples containing vanadium (V), cobalt (Co), zink (Zn), copper (Cu), chrome (Cr), mercury (Hg), As, Pb and Cd are digested with aqua regia and used for analysis. Concentrations of selected elements are determined using MICAP-MS and validated using ICP-MS. Sensitivities, limits of detection and gas consumption for both methods are compared and discussed in detail. Moreover, the performance of MICAP-MS under different nitrogen plasma gas concentrations is investigated and compared.
Inductively coupled plasma mass spectrometry (ICP-MS) emerged as a powerful technique for trace analysis of soil due to its multi-element capability, high sensitivity and low sample consumption. However, despite its success and widespread use, ICP-MS has several persistent drawbacks, such as high argon gas consumption, argon-based polyatomic interferences and the need for complicated RF-power generators. Unlike argon-based ICP, the nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) uses nitrogen as plasma gas, which eliminates high operating costs associated with argon-gas consumption as well as the argon-based interferences1. In this work, the applicability of MICAP-MS for elemental analysis in different matrices is investigated. For this purpose, reference soil samples and steel samples are digested with aqua regia and used for analysis. Concentrations of selected elements are determined using MICAP-MS and validated with ICP-MS und certified values. Sensitivities, limits of detection and gas consumption for both methods are compared and discussed in detail. Performance of MICAP-MS under different nitrogen plasma gas concentrations is investigated and compared. Moreover, the performance of MICAP-MS in alloy matrices is investigated and discussed.
Trace elemental analysis in human serum is integral in both clinical and research settings. Analyzing the level of some specific elements like Se and Zn helps indicate the nutritional and health status. Furthermore, elucidating the roles of trace elements in various physiological and pathological conditions can shed light on disease mechanisms and potential treatments. Inductively coupled plasma mass spectrometry (ICP-MS) stands out as a preeminent method for trace elemental analysis, given its exceptional sensitivity and minimal sample requirements. However, ICP-MS has challenges, such as argon-related interferences that hinder the accurate quantification of elements like Ca, Fe, and Se. The naturally most abundant isotopes of Ca (40Ca), Fe (56Fe), and Se (80Se) are subject to isobaric interference from 40Ar+, 40Ar16O+, and 40Ar2+, thereby complicating their direct measurement and preventing isotope dilution analysis.
In response to these challenges, nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) emerges as a viable alternative to ICP-MS, eliminating argon consumption and associated interferences. This study employed MICAP-MS to quantify Ca, Fe, and Se in 11 certified reference human serums using matrix-matched calibration and isotope dilution with the isotopes 40Ca, 56Fe, and 80Se. The results obtained with both methods were validated against certified values, and the suitability of MICAP-MS for isotope dilution was evaluated. Additionally, the performance of MICAP-MS in the Na matrix was investigated and discussed alongside the impact of organic species.