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Faecal contaminants in water are considered serious threats for human health, due to the presence of viruses, bacteria and other harmful microorganisms.1 Urobilin (UB) is a well-known faecal pigment and can be used as a marker for faecal matter in water.2 UB is commonly present in the urine of all mammals as the catabolic end product of bilirubin degradation.2 As the only simple chemical approach to its detection, Schlesinger’s test is usually used to enhance the weak fluorescence of UB in alcoholic media by complexation with Zinc.2, 3 The major limitation of this method is the only weak enhancement of the intrinsically weak UB fluorescence in aqueous media.3 This work presents an approach to introduce different Zn salts for improved fluorescence response, where we found a clear dependence of the fluorescence yield of UB-Zn(II) complexes on the counterion of the salt in water. By employing a combination of fluorescence parameters like transition energy, fluorescence intensity, and fluorescence lifetime, a photophysical understanding of the structure and conformation of the UB-Zn(II) complexes responsible for the fluorescence enhancement in water could be gained. The possibilities of developing a sensitive analytical method based on the acquired understanding are also discussed.
This contribution reports the development of a polymerizable BODIPY-type fluorescent probe targeting small-molecule carboxylates for incorporation into molecularly imprinted polymers (MIPs). The design of the probe crosslinker includes a urea recognition site p-conjugated to the 3-position of the BODIPY core and two methacrylate moieties. Titration experiments with a carboxylate-expressing antibiotic, levofloxacin (LEVO), showed a blue shift of the absorption band as well as a broadening and decrease in emission, attributed to hydrogen bonding between the probe’s urea group and the carboxylate group of the antibiotic. Using this probe crosslinker, core–shell particles with a silica core and a thin MIP shell were prepared for the detection of LEVO. The MIP exhibited highly selective recognition of LEVO, with an imprinting factor of 18.1 compared to the non-imprinted polymer. Transmission electron microscopy confirmed the core–shell structure and spectroscopic studies revealed that the receptor’s positioning leads to a unique perturbation of the polymethinic character of the BODIPY chromophore, entailing the favourable responses. These features are fully preserved in the MIP, whereas no such response was observed for competitors such as ampicillin. The sensory particles allowed to detect LEVO down to submicromolar concentrations in dioxane. We have developed here for the first time a BODIPY probe for organic carboxylates and incorporated it into polymers using the imprinting technique, paving the way for BODIPY-type fluorescent MIP sensors.
Wie können industriell synthetisierte Schadstoffe aus einer Stoffklasse quantifiziert werden, deren genauer Umfang unbekannt ist und auf mehrere tausend Verbindungen geschätzt wird? Im Falle der per- und polyfluorierten alkylierten Substanzen (PFAS) stellen sich Wissenschaftler*innen weltweit seit über zehn Jahren diese Frage. Neben der etablierten Methodik der Einzelstoffanalytik (engl. target analytic) existieren Summenparameteranalysen zur Quantifizierung
organisch gebundener fluorierter Verbindungen in Umweltmedien und Konsumprodukten. An der Bundesanstalt für Materialforschung und -prüfung (BAM) beschäftigen wir uns mit der Weiterentwicklung von Summenparametermethoden am Beispiel von PFAS-belasteten Umweltkompartimenten wie Böden, Klärschlämmen und Gewässerproben sowie PFAS-haltigen Konsumgütern. In diesem Beitrag stellen wir zwei ausgewählte Fallbeispiele vor und diskutieren die Vor- und Nachteile der Methoden im Vergleich zur Einzelstoffanalytik.
Increasing contamination of environmental waters with pharmaceuticals represents an emerging threat for the drinking water quality and safety. In this regard, fast and reliable analytical methods are required to allow quick countermeasures in case of contamination. Here, we report the development of a magnetic bead-based immunoassay (MBBA) for the fast and cost-effective determination of the analgesic diclofenac (DCF) in water samples, based on diclofenac-coupled magnetic beads and a robust monoclonal anti-DCF antibody. A novel synthetic strategy for preparation of the beads resulted in an assay that enabled for the determination of diclofenac with a significantly lower limit of detection (400 ng/L) than the respective enzyme-linked immunosorbent assay (ELISA). With shorter incubation times and only one manual washing step required, the assay demands for remarkably shorter time to result (< 45 min) and less equipment than ELISA. Evaluation of assay precision and accuracy with a series of spiked water samples yielded results with low to moderate intra- and inter-assay variations and in good agreement with LC–MS/MS reference analysis. The assay principle can be transferred to other, e.g., microfluidic, formats, as well as applied to other analytes and may replace ELISA as the standard immunochemical method.
Contamination of natural bodies of water with oil and lubricants (or generally, hydrocarbon derivatives such as petrol, fuel and others) is a commonly found phenomenon around the world due to the extensive production, transfer and use of fossil fuels. The timely identification of these contaminants is of utmost importance, since they directly affect water quality and represent a risk for wildlife and human health even in trace amounts.
In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPH) in water and soil, the "Spectrocube". The test is based on the measurement of the fluorescence signal emitted by the molecular rotor 4-DNS-OH dye. This dye is embedded in a hydrophobic polymeric matrix (PVDF), avoiding interactions of water with the dye and providing a robust support for use in test-strip fashion. The test-strip’s fluorescence intensity increases linearly at low concentrations of TPH, reaching a saturation value at higher concentrations.
For excitation and evaluation of the test-strip fluorescence, a simple miniature optical system was designed. The system works semi-quantitatively as solvent-free TPH detection kit, as well as quantitatively when using a simple cyclopentane extraction step. To simplify the fluorescence read-out, the device is coupled to a tablet computer via Bluetooth, running a self-programmed software ("app").
The European Water Framework Directive (WFD) 2000/60/EC specifies a list of 33 priority water pollutants. For these substances, Environmental Quality Standards (EQS), equivalent to the maximum allowable concentrations, had been defined at very low levels.
EQS values refer to the whole water body, i.e. include contaminants which are associated to suspended solids or colloids present in the natural water. For several priority pollutants primary analytical methods capable of measuring the target analytes at EQS level in natural water are still missing. The project has developed and validated such methods for three selected compounds, namely Tributyltin (TBT), Polybrominated Diphenylether (PBDE) and Polycyclic Aromatic Hydrocarbons (PAH).