Development and application of high resolution mass spectrometry analytical method to study and identify the photoinduced transformation products of environmental pollutants

Exploring the hidden chemical landscape: Non-target and suspect screening analysis for investigating solid waste-associated environments

Solid waste is an inevitable consequence of urbanization. It can be safely managed in municipal landfills and processing plants for volume reduction or material reuse, including organic solid waste. However, solid waste can also be discarded in (un-)authorized dumping sites or inadvertently released into the environment. Legacy and emerging contaminants have the potential to leach from solid waste, making it a significant pathway to the environment. Non-target screening (NTS) and suspect screening analysis (SSA) have become helpful tools in environmental science for the simultaneous analysis of a wide range of chemical compounds. However, the application of these analytical approaches to environmental samples related to Raw or Processed Solid Waste (RPSW) has been largely neglected so far. This perspective review examines the potential and policy relevance of NTS and SSA applied to waste-related samples (liquid, gaseous and solid). It addresses the hurdles associated with the chemical safety of solid waste accumulation, processing, and reuse, and the need for landfill traceability, as well as effectiveness of leachate treatments. We reviewed the current applications of NTS and SSA to environmental samples of RPSW, as well as the potential adaptation of NTS and SSA techniques from related fields, such as oilfield and metabolomics, to the solid waste domain. Despite the ongoing technical challenges, this review highlights the significant potential for the implementation of NTS and SSA approaches in solid waste management and related scientific fields and provides support and guidance to the regulatory authorities.

Improvement of photocatalytic activity in the degradation of 4-chlorophenol and phenol in aqueous medium using tin-modified TiO2 photocatalysts

In this work, we present the synthesis of TiO₂ photocatalysts modified with different % mol of tin using the sol-gel method. The materials were characterized using different analytical techniques. The Rietveld refinement, XPS, Raman and UV-Vis techniques confirm the substitution of tin in the TiO₂ structural lattice due to changes in crystal lattice parameters, the low-energy shift of the Sn 3d_5/2 orbital, generation of oxygen vacancies and the decreased band gap and increased BET surface area. The material with 1 mol% tin shows superior catalytic activity compared to the references for the degradation of 40 ppm 4-chlorophenol (3 hours of reaction) and 50 ppm phenol (6 hours of reaction). Reactions fit pseudo first order kinetics in both instances. The increase in photodegradation efficiency was attributed to the generation of energy levels below the TiO₂ conduction band caused by the incorporation of 1% mol of tin, oxygen vacancies, and the heterojunction formed between the brookite-anatase-rutile, causing inhibition of the recombination of the electron (e^-) and hole (h⁺) photogenerated species. The easy synthesis, low cost and increased photodegradation efficiency of the photocatalyst with 1 mol% tin have the potential to favor the remediation of recalcitrant compounds in water.

Solar photodegradation of irinotecan in water: optimization and robustness studies by experimental design

Irinotecan, a widely prescribed anticancer drug, is an emerging contaminant of concern that has been detected in various aquatic environments due to ineffective removal by traditional wastewater treatment systems. Solar photodegradation is a viable approach that can effectively eradicate the drug from aqueous systems. In this study, we used the design of experiment (DOE) approach to explore the robustness of irinotecan photodegradation under simulated solar irradiation. A full factorial design, including a star design, was applied to study the effects of three parameters: initial concentration of irinotecan (1.0-9.0 mg/L), pH (5.0-9.0), and irradiance (450-750 W/m²). A high-performance liquid chromatography coupled with a high-resolution mass spectrometry (HPLC-HRMS) system was used to determine irinotecan and identify transformation products. The photodegradation of irinotecan followed a pseudo-first order kinetics. In the best-fitted linear model determined by the stepwise model fitting approach, pH was found to have about 100-fold greater effect than either irinotecan concentration or solar irradiance. Under optimal conditions (irradiance of 750 W/m², 1.0 mg/L irinotecan concentration, and pH 9.0), more than 98% of irinotecan was degraded in 60 min. With respect to irradiance and irinotecan concentration, the degradation process was robust in the studied range, implying that it may be effectively applied in locations and/or seasons with solar irradiance as low as 450 W/m². However, pH needs to be strictly controlled and kept between 7.0 and 9.0 to maintain the degradation process robust. Considerations about the behavior of degradation products were also drawn.

Time-Series-Dependent Global Data Filtering Strategy for Mining and Profiling of Xenobiotic Metabolites in a Dynamic Complex Matrix: Application to Biotransformation of Flavonoids in the Extract of Ginkgo biloba by Gut Microbiota

Efficient characterization of xenobiotic metabolites and their dynamics in a changing complex matrix remains difficult. Herein, we proposed a time-series-dependent global data filtering strategy for the rapid and comprehensive characterization of xenobiotic metabolites and their dynamic variation based on metabolome data. A set of data preprocessing methods was used to screen potential xenobiotic metabolites, considering the differences between the treated and control groups and the fluctuations over time. To further identify metabolites of the target, an in-house accurate mass database was constructed by potential metabolic pathways and applied. Taking the extract of Ginkgo biloba (EGB) co-incubated with gut microbiota as an example, 107 compounds were identified as flavonoid-derived metabolites (including 67 original from EGB and 40 new) from 7468 ions. Their temporal metabolic profiles and regularities were also investigated. This study provided a systematic and feasible method to elucidate and profile xenobiotic metabolism.