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In this proof-of-concept study, we explore the detection of pesticides in food using a combined power of sensitive UV-induced fingerprint spectroscopy with selective capture by molecularly imprinted polymers (MIPs) and portable cost-effective paper-based analytical devices (PADs). The specific pesticides used herein as model compounds (both pure substances and their application products for spraying), were: strobilurins (i.e. trifloxystrobin), urea pesticides (rimsulfuron), pyrethroids (cypermethrine) and aryloxyphenoxyproponic acid herbicides (Haloxyfop-methyl). Commercially available spraying formulations containing the selected pesticides were positively identified by MIP-PADs swabs of sprayed apple and tomato. The key properties of MIP layer - imprinting factor (IF) and selectivity factor (α) were characterized using trifloxystrobin (IF-3.5, α-4.4) was demonstrated as a potential option for in-field application. The presented method may provide effective help with in-field testing of food and reveal problems such as false product labelling., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In this work, we explored a new approach to a simple and sensitive fluorescence detection of thiols. The approach takes advantage of an in-situ formation of UV light-induced fluorescent nanoparticles (ZnCd/S quantum dots), while utilizing the thiol group of the analyte as a capping agent. The selectivity is ensured by the selective isolation of the thiol analyte by a polydopamine molecularly imprinted polymeric (MIP) layer. Based on this approach, a method for determination of thiols was designed. Key experimental parameters were optimized, including those of molecular imprinting and of effective model thiol molecule (L-cysteine) isolation. The relationship between the fluorescence intensity of ZnCd/S quantum dots and the concentration of L-cysteine in the range of 12-150 µg/mL was linear with a detection limit of 3.6 µg/mL. The molecularly imprinted polymer showed high absorption mass capacity (1.73 mg/g) and an excellent selectivity factor for L-cysteine compared to N-acetyl-L-cysteine and L-homocysteine of 63.56 and 87.48, respectively. The proposed method was applied for L-cysteine determination in human urine with satisfactory results. Due to a high variability of molecular imprinting technology and versatility of in-situ probe formation, methods based on this approach can be easily adopted for analysis of any thiol of interest.

Synthesis of RNA nucleobases from formamide is one of the recurring topics of prebiotic chemistry research. Earlier reports suggest that thymine, the substitute for uracil in DNA, may also be synthesized from formamide in the presence of catalysts enabling conversion of formamide to formaldehyde. In the current paper, we show that to a lesser extent conversion of uracil to thymine may occur even in the absence of catalysts. This is enabled by the presence of formic acid in the reaction mixture that forms as the hydrolysis product of formamide. Under the reaction conditions of our study, the disproportionation of formic acid may produce formaldehyde that hydroxymethylates uracil in the first step of the conversion process. The experiments are supplemented by quantum chemical modeling of the reaction pathway, supporting the plausibility of the mechanism suggested by Saladino and coworkers.

In this work, a novel method was developed, for isolation of S. aureus from complex (food) samples using molecular imprinting.  Dopamine was used as a functional monomer and fluorescence microscopy was used for detection. Conditions for preparation of molecularly imprinted polymers (MIPs), adsorption performance, adsorption kinetic, and selectivity of the polymeric layers were investigated. The various procedures were combined in a single extraction process, with the imprinted layer on the surface of the magnetic particles (magnetic MIPs). Subsequently, MIPs were used for extraction of S. aureus from milk and rice. Moreover, raw milk from cows with mastitis was tested successfully. Using this novel MIP-based method, it was possible to detect bacteria in milk at 1 × 10 3 CFU·ml -1 , which corresponds to the limit set in European Union legislation for microbial control of food., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Inorganic nanoparticles might have played a vital role in the transition from inorganic chemistry to self-sustaining living systems. Such transition may have been triggered or controlled by processes requiring not only versatile catalysts but also suitable reaction surfaces. Here, experimental results showing that multicolor quantum dots might have been able to participate as catalysts in several specific and nonspecific reactions, relevant to the prebiotic chemistry are demonstrated. A very fast and easy UV-induced formation of ZnCd quantum dots (QDs) with a quantum yield of up to 47% was shown to occur 5 min after UV exposure of the solution containing Zn(II) and Cd(II) in the presence of a thiol capping agent. In addition to QDs formation, xanthine activity was observed in the solution. The role of solar radiation to induce ZnCd QDs formation was replicated during a stratospheric balloon flight.

Dairy cow feed contains, among other ingredients, soybeans, legumes, and clover, plants that are rich in phytoestrogens. Several publications have reported a positive influence of phytoestrogens on human health; however, several unfavorable effects have also been reported. In this work, a simple, selective, and eco-friendly method of phytoestrogen isolation based on the technique of noncovalent molecular imprinting was developed. Genistein was used as a template, and dopamine was chosen as a functional monomer. A layer of molecularly imprinted polymers was created in a microtitration well plate. The binding capability and selective properties of obtained molecularly imprinted polymers were investigated. The imprinted polymers exhibited higher binding affinity toward chosen phytoestrogen than did the nonimprinted polymers. A selectivity factor of 6.94 was calculated, confirming satisfactory selectivity of the polymeric layer. The applicability of the proposed sensing method was tested by isolation of genistein from a real sample of bovine milk and combined with micellar electrokinetic capillary chromatography with UV-visible detection., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The formation of new atmospheric particles involves an initial step forming stable clusters less than a nanometre in size (<~1 nm), followed by growth into quasi-stable aerosol particles a few nanometres (~1-10 nm) and larger (>~10 nm). Although at times, the same species can be responsible for both processes, it is thought that more generally each step comprises differing chemical contributors. Here, we present a novel analysis of measurements from a unique multi-station ground-based observing system which reveals new insights into continental-scale patterns associated with new particle formation. Statistical cluster analysis of this unique 2-year multi-station dataset comprising size distribution and chemical composition reveals that across Europe, there are different major seasonal trends depending on geographical location, concomitant with diversity in nucleating species while it seems that the growth phase is dominated by organic aerosol formation. The diversity and seasonality of these events requires an advanced observing system to elucidate the key processes and species driving particle formation, along with detecting continental scale changes in aerosol formation into the future.

This paper describes a method of estimating emission fluxes of biogenic volatile organic compounds (BVOCs) based on the approach proposed by Guenther et al. (1995) and the high-resolution Corine land-cover 2000 database (1x1km resolution). The computed emission fluxes for the Czech Republic (selected for analysis as being representative of a heavily cultivated, central European country) are compared with anthropogenic emissions, both for the entire country and for individual administrative regions. In some regions, BVOC emissions are as high as anthropogenic emissions; however, in most regions the BVOC emissions are approximately 50% of the anthropogenic emissions. The yearly course of BVOC emissions (represented by monoterpenes and isoprene) is presented, along with the spatial distribution of annual mean values. Differences in emission distributions during winter (January) and summer (June) are also considered., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)