High-Resolution MS and MSn Investigation of UV Oxidation Products of Phenazone-type Pharmaceuticals and Metabolites

Assessing the pharmaceutical residues as hotspots of the main rivers of Catalonia, Spain

The global increase in pharmaceutical consumption, driven by factors such as aging populations and chronic diseases, has raised concerns regarding the environmental impact of pharmaceutical contaminants. Europe, and more specifically Catalonia (Spain), exhibits high pharmaceutical consumption rates, potentially exacerbating environmental contamination. Pharmaceuticals enter rivers through various pathways, persisting after wastewater treatment plants and posing risks to aquatic organisms and human health. Llobregat and Besòs Rivers in Catalonia, crucial water sources, demonstrate detectable pharmaceutical levels, necessitating comprehensive analysis. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) proves effective in detecting pharmaceutical residues, facilitating their risk assessment. This paper reviews the occurrence, fate, and risks associated with 78 pharmaceuticals and metabolite in Llobregat and Besòs Rivers, using LC-MS/MS for analysis. Understanding pharmaceutical impacts on Catalonian River ecosystems is essential for developing mitigation strategies.

Environmental occurrence, risk, and removal strategies of pyrazolones: A critical review

Pyrazolones, widely used as analgesic and anti-inflammatory pharmaceuticals, have become a significant concern because of their persistence and widespread presence in engineered (e.g., wastewater treatment plants) and natural environments. Thus, the urgent task is to ensure the effective and cost-efficient removal of pyrazolones. Advanced oxidation processes are the most commonly used removal method. Furthermore, the biodegradation of pyrazolones has been exploited using microbial communities or pure strains; however, screening for efficient degrading bacteria and clarifying the biodegradation mechanisms required further research. In this critical review, we overview the environmental occurrence of pyrazolones, their potential ecological health risks, and their corresponding removal techniques (e.g., O3 oxidation, photocatalysis, and Fenton-like process). We also emphasize the prospects for the risk and contamination control of pyrazolones in various environments using physicochemical-biochemical coupling technology. Collectively, the environmental occurrence of pyrazolones poses significant public health concerns, necessitating heightened attention and the implementation of effective methods to minimize their environmental risks.

Efficient elimination of phenazone by an electro-assisted Fe3+-EDDS/PS process at neutral pH: Kinetics, mechanistic insights and toxicity evaluation

The feasibility of the degradation of phenazone (PNZ), a common anti-inflammatory drug used for reducing pain and fever, in water at neutral pH by an electrochemically assisted Fe³⁺-ethylenediamine disuccinate-activated persulfate process (EC/Fe³⁺-EDDS/PS) was investigated. The efficient removal of PNZ at neutral pH condition was mainly attributed to the continuous activation of PS via electrochemically driven regenerated Fe²⁺ from a Fe³⁺-EDDS complex at the cathode. The influence of several critical parameters, including current density, Fe³⁺ concentration, EDDS to Fe³⁺ molar ratio, and PS dosage, on PNZ degradation was evaluated and optimized. Both hydroxyl radicals (•OH) and sulfate radicals (SO₄^●-) were considered major reactive species responsible for PNZ degradation. To understand the mechanistic model of action at the molecular level, the thermodynamic and kinetic behaviors of the reactions between PNZ with •OH and SO₄^●- were theoretically calculated using a density functional theory (DFT) method. The results revealed that radical adduct formation (RAF) is the most favorable pathway for the •OH-driven oxidation of PNZ, while single electron transfer (SET) appears to be the dominant pathway for the reaction of SO₄^●- with PNZ. In total, thirteen oxidation intermediates were identified, and hydroxylation, pyrazole ring opening, dephenylization, and demethylation were speculated to be the major degradation pathways. Furthermore, predicted toxicity to aquatic organisms indicated that PNZ degradation resulted in products that were less harmful. However, the developmental toxicity of PNZ and its intermediate products should be further investigated in the environment. The findings of this work demonstrate the viability of effectively removing organic contaminants in water at near-neutral pH by using EDDS chelation combined with electrochemistry in a Fe³⁺/persulfate system.

Oxidation of pyrazolone pharmaceuticals by peracetic acid: Kinetics, mechanism and genetic toxicity variations

Peracetic acid (PAA) oxidation is an emerging technology in water disinfection and purification. This study evaluated the oxidation of three pyrazolone pharmaceuticals (i.e., Aminopyrine (AMP), Antipyrine (ANT), and Isopropylphenazone (PRP) by PAA. Experimental results showed that PAA exhibited structure selectivity to the above three pharmaceuticals and oxidized AMP with the highest reactivity. The degradation kinetics of AMP was investigated by calculating the apparent second-order rate constants (k_app) under different initial pH. Through kinetic simulation, the second-order rate constants of elementary reactions between AMP (i.e., neutral (AMP⁰) and protonated (AMP⁺) species) with PAA (i.e., neutral (PAA⁰) and anionic (PAA^-) species) were obtained to be 0.34 ± 0.077 M^-1 s^-1(k"_{AMP+, PAA0}), 0.89 ± 0.091 M^-1 s^-1(k"_{AMP0, PAA-}) and 5.94 ± 0.142 M^-1 s^-1(k"_{AMP0, PAA0}), respectively. The PAA could oxidize AMP via electrophilic attack, and the degradation site of AMP was confirmed to be the central nitrogen of -N(CH₃)₂ with the highest relative electrophilicity (s_k^-/s_k⁺, 48.8614) by Density Functional Theory (DFT) calculation. The intermediates/products of AMP degradation were identified by high-performance liquid chromatography-mass spectrometry (LC-MS/MS), and the transformation pathways of AMP during PAA oxidation were inferred to be hydroxylation, demethylation, and CC cleavage. The genetic toxicity of AMP contaminated water could be reduced after PAA oxidation, which was evaluated by the micronucleus test of Vicia faba root tips.

Efficiency and mechanism of diclofenac degradation by sulfite/UV advanced reduction processes (ARPs)

Diclofenac (DCF) is a non-steroidal anti-inflammatory drug which is frequently detected in the aqueous environment. The synergistic treatment using sulfite and UV irradiation is proposed to be one of the most effective advanced reduction processes (ARPs) to degrade refractory contaminants. This paper systematically investigated the performance and mechanism of DCF degradation by sulfite/UV ARP under various conditions. A significant enhancement in degradation efficiency of DCF was exhibited via sulfite/UV ARP compared with direct UV photolysis, which is primarily due to the generation of reductive radicals (e_aq^- and H). This process was well described by a pseudo first-order kinetic model with a rate constant of 0.154 min^-1. The influence of solution pH, sulfite dosage, initial DCF concentration and UV intensity were evaluated. Results revealed that DCF more favorably reacted with H in an acidic environment than with e_aq^- under alkaline conditions. A positive impact on the DCF decomposition was observed with increasing sulfite dosage, but with an inhibiting trend at high sulfite concentrations. The degradation rate constant was accelerated by increasing the UV intensity, while decreased by promoting the initial DCF concentration. Degradation mechanisms at different pH levels revealed that the reduction reactions were induced by e_aq^- at pH 9.2, and dominated by H at pH 6.0. Complete dechlorination was readily achieved with all chlorine atoms in DCF released as chloride ions under sulfite/UV ARP, which may lead to a decreased toxicity of the degradation products. This observation emphasized the advantages of sulfite/UV ARP on DCF degradation, in comparison with that under direct UV photolysis.