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Chlorination of pool water and wastewater, in food and pharmaceutical production, as well as in pesticide and paper manufacturing is a routinely used technique. However, the amount of chlorine in water must be strictly adjusted, to ensure enough concentration to kill pathogenic bacteria and viruses, while preventing too high concentrations inducing negative effects on human health. As an indicator, a molecular fluorescent probe based on a BODIPY structure was designed. This indicator exhibits a sensitive and selective fluorescence response upon increasing concentrations of hypochlorite in aqueous solvent mixtures. Real-time analyses became possible after the integration of this fluorescent indicator into newly designed 2D & 3D microfluidic chips incorporating a passive sinusoidal mixer and a micro-hydrocyclone, respectively. A comparison of the two microfluidic systems, including their ability to prevent accumulation or circulation of microbubbles, has shown excellent fluidic behaviour for the micro-hydrocyclone device. This system was distinctly more robust against gas bubbles, showed a higher signal gain and allowed to halve the limit of detection to 0.02 mg L–1. The use of the 3D system to quantify the chlorine content of pool water samples for sensitive and quantitative chlorine monitoring has been demonstrated.
A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilities relying on sustainable gold catalysis has been developed. A key to the tailored pyrrole precursors is the gold catalysis performed in ionic liquids as the reaction medium, allowing a facile recycling of the catalysts. The dyes prepared are well-matching with the spectral windows of popular rhodamine dyes and possess high brightness while showing a distinctly higher photostability than the rhodamines especially in aprotic solvents.
Gasoline adulteration is a frequent problem world-wide, because of the chance of quick, maximized profits. However, addition of cheaper ethanol or hydrocarbons like kerosene does not only result in economic damage but also poses problems for vehicles and the environment. To enable law enforcement forces, customers or enterprises to uncover such a fraudulent activity directly upon suspicion and without the need to organize for sampling and laboratory analysis, we developed a simple strip-based chemical test. Key to the favorable performance was the dedicated materials tailoring, which led to test strips that consisted of a cellulose support coated with silica, passivated with hexamethyldisilazane and functionalized covalently with a molecular probe. The probe fluoresces brightly across a broad solvent polarity range, enabling reliable quantitative measurements and data analysis with a conventional smartphone. The assays showed high reproducibility and accuracy, allowing not only for the detection of gasoline adulteration but also for the on-site monitoring of the quality of commercial E10 gasoline.
Contamination of natural bodies of water or soil with oils and lubricants (or generally, hydrocarbon derivatives such as petrol, fuels, and others) is a commonly found phenomenon around the world due to the extensive production, transfer, and use of fossil fuels. In this work, we develop a simple system for the on-field detection of total petroleum hydrocarbons (TPHs) in water and soil. The test is based on the measurement of the fluorescence signal emitted by the molecular rotor 2-[ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol (4-DNS-OH). This dye is embedded in a hydrophobic polymeric matrix (polyvinylidene fluoride), avoiding interactions with water and providing a robust support for use in a test strip fashion. Together with the strips, an embedded optical system was designed for fluorescence signal read-out, featuring a Bluetooth low-energy connection to a commercial tablet device for data processing and analysis. This system works for the detection and quantification of TPHs in water and soil through a simple extraction protocol using a cycloalkane solvent with a limit of detection of 6 ppm. Assays in surface and sea waters were conclusive, proving the feasibility of the method for in-the-field operation.