Analytische Chemie
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Eingeladener Vortrag
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Reliable analysis of chemical indicators in water, sediment and soil samples for the purpose of environmental pollution assessment poses one of the greatest analytical challenges, having in mind the complexity of sample matrix and low concentrations of pollutants. Organics (pesticides, PAHs, PCBs, etc.) and heavy metals (Hg, Cd, Ni, Pb and As) represent target parameters. Laboratories performing sampling and tests in this field regulated by respective EU directives, need strong support in terms of providing them with appropriate matrix CRMs enabling the process of quality control. NMIs and DIs with proven metrological capabilities for the production and certification of such materials are necessary for the provision of quality data. This project is aiming to develop capacity to produce CRMs for environmental analysis by transferring the theoretical and practical know-how between the partners and combining their skills to focus on environmental CRM production in accordance with ISO Guide 34. Production process includes good manufacturing practices for processing materials, method development and validation for homogeneity, stability and characterisation tests, characterisation of selected analytes together with additional information about matrix constituents, the calculation of individual uncertainties (between units inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. Inter laboratory comparison registered as EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.
Reliable analysis of chemical indicators in water, sediment and soil samples for the purpose of environmental pollution assessment poses one of the greatest analytical challenges, having in mind the complexity of sample matrix and low concentrations of pollutants. Organics (pesticides, PAHs, PCBs, etc.) and heavy metals (Hg, Cd, Ni, Pb and As) represent target parameters. Laboratories performing sampling and tests in this field regulated by respective EU directives [1], need strong support in terms of providing them with appropriate matrix CRMs enabling the process of quality control. NMIs and DIs with proven metrological capabilities for the production and certification of such materials are necessary for the provision of quality data. This project is aiming to develop capacity to produce CRMs for environmental analysis by transferring the theoretical and practical know-how between the partners and combining their skills to focus on environmental CRM production in accordance with ISO Guide 34 [2]. Production process includes good manufacturing practices for processing materials, method development and validation for homogeneity, stability and characterisation tests, characterisation of selected analytes together with additional information about matrix constituents, the calculation of individual uncertainties (between units inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. Inter laboratory comparison registered as EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.
The use of magnetic materials as heterogeneous catalysts has attracted increasing attention in the last years since they proved to be promising candidates for water treatment. In the present study, two types of surface-modified magnetite (Fe3O4) nanoparticles, coated with non-hazardous naturally occurring agents—either tannic acid (TA) or dissolved natural organic matter—were evaluated as magnetic heterogeneous catalysts. Chemical synthesis (co-precipitation) was chosen to yield the nanocatalysts due to its well-established simplicity and efficiency. Subsequently, the properties of the final products were fully assessed by various characterization techniques. The catalytic activity in heterogeneous oxidation of aqueous solutions containing a model pollutant, Bisphenol A (BPA), was comparatively studied. The effect of operational parameters (catalyst loading, H2O2 dosage, and UV light irradiation) on the Degradation performance of the oxidation process was investigated. The optimum experimental parameters were found to be 1.0 g/L of catalysts and 10 mM H2O2, under UV irradiation. The highest mineralization rates were observed for Fe3O4-TA catalyst. More than 80 % of BPA was removed after 30 min of reaction time under the specified experimental conditions. The obtained results showed that the two catalysts studied here are suitable candidates for the removal of pollutants in wastewaters by means of heterogeneous reaction using a green sustainable treatment method.
Due to the demand of monitoring the water quality regarding emerging pollutants, such as drug residues, selective, high-throughput and multi-target analytical methods must be established. On the one hand, the influence of sewage on natural surface waters must be routinely monitored. On the other hand, estimation of removal efficiencies of pollutants, such as drug residues, is in the focus of industrial and public wastewater treatment. Immunoassays, such as ELISA, offer the possibility to be highly sensitive and selective due to the high target affine and specific recognition of antibodies to target molecules. Batch-wise processing in microtiter plates allow the necessary high-throughput, but only a single analyte can be determined within one measurement.
To overcome these disadvantages, we developed a four-plex micro-bead based flow cytometric assay, which is adaptable for the microtiter plate format. The modular and self-prepared bead support consists of polystyrene-core-silica-shell particles. While the polystyrene core is used for encoding, by introducing different amounts of fluorescent dyes, the silica-shell creates a solid-support for the immunoassay: The target analytes, three drugs, carbamazepine, diclofenac and caffeine and the f ecal marker isolithocholic acid are covalently coupled to amino-groups on the surface via NHS-chemistry. A competitive immunoassay is subsequently conducted in a simple mix-and-read procedure. Finally, we could use SAFIA to assess the influent of treated and untreated waste water on the Douro river estuary in Portugal. The results of the analysis are comparable to ELISA. However, measurements could be carried out in 25% the time of analysis.
Coumarin-rhodamine hybrids-novel probes for the optical measurements of viscosity and polarity
(2017)
A comprehensive systematic study of Absorption and fluorescence properties in solvents of varying viscosity and polarity of three novel and red-emitting coumarin-rhodamine hybrid derivatives with differences in the rigidity of their substituents is presented. This includes ethanol-polyethylene glycol, toluene-polyethylene glycol, and tolueneparaffin mixtures. Moreover, protonation-induced effects on the spectroscopic properties are studied. A viscosity-induced emission enhancement was observed for all coumarin-rhodamine hybrid derivatives. MCR2 bearing a julolidine donor showed the expected low sensitivity to viscosity whereas MCR3 with its freely rotatable diphenylamino Substituent revealed a particularly pronounced sensitivity to this parameter.
Moreover, MCR2 shows an enhancement in Emission in the open, i.e., protonated form in conjunction with a largely Stokes shift fluorescence in the deep red spectral region. This enables the application of these dyes as viscosity sensors and as far red emitting pH-sensitive probes.
The unparalleled excited-state potential-energy landscape of the chromium(III)-based dye [1]3+ ([Cr(ddpd)2]3+; ddpd=N,N’-dimethyl-N,N’-dipyridin-2-ylpyridin-2,6-diamine) enables a strong dual emission in the near infrared region. The temperature dependence of this dual emission allows the use of [1]3+ as an unprecedented molecular ratiometric thermometer in the 210–373 K temperature range in organic and in aqueous media. Incorporation of [1]3+ in biocompatible nanocarriers, such as 100 nm-sized polystyrene nanoparticles and solutol micelles, provides nanodimensional thermometers operating under physiological conditions.
Structural design and application have always been linked to the compressive strength of concrete as the main relevant criterion. This was justifiable in the past, where concrete consisted of water, ordinary Portland cement and aggregates, but this concept is no longer relevant for modern and more sustainable cement and concrete.
Despite these new developments, existing standards, guidelines and academic curricula have not been much updated and are still used worldwide. There is a need to change this situation by proper education of the users.
This overview describes the challenges that arise at a user Level from the higher complexity of modern concrete, and defines needs and requirements for enhanced applicability of sustainable concrete concepts.
Furthermore, recommendations are given on how better concrete practice can be communicated to all the involved parties, from civil and design engineers to constructors and site-appliers on the construction site.
This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
In summary, by combining the NIR-emissive [Cr(ddpd)2][BPh4]3 complex CrBPh4 with its extremely large energy gap between the longest wavelength absorption and emission maxima with a pH-responsive fluorescein derivative (FITC) and an inert reference dye like Nile Red (NR) and 5,10,15,20tetrakis(pentafluorophenyl) porphyrin (TFPP), we developed nanosensors for simultaneously sensing temperature, O2 partial pressure, and pH. These novel TOP nanosensors (temperature, oxygen, pH) cover the biologically and physiologically relevant concentration ranges of these parameters/analytes with single wavelength excitation in PBS buffer and in a cell culture medium containing bovine serum albumin (BSA). The response of both nanosensors to all parameters is fully reversible and only minimally affected by the presence of BSA, the most common serum albumin. Moreover, comparative studies with nanosensors containing only a single type of stimuli-responsive molecule and with the respective molecular systems revealed that the different sensor components do not interfere with each other. Future research will include the testing of these nanosensors in cellular uptake studies and, after surface modification with targeted bioligands, eventually in in vivo experiments as previously done by some of us with other polystyrene nanoparticle reporters and nanosensors.46,47 Moreover, this concept of multianalyte sensing will be expanded to nanosensors derived from differently sized premanufactured biocompatible polymer particles and different stimuli-responsive dyes like fluorescent indicators for biologically and bioanalytically relevant metal ions.
Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nmsized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near-infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20tetrakis(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pHsensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands, allowing for ratiometric intensity-based and time-resolved studies in the visible and near-infrared wavelength region. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of these nanosensors for the sensitive luminescence readout of TOP simultaneously at the same spatialposition.