Occurrence, toxicity and risk assessment of plastic additives in Besos river, Spain.

The objective of the present study is to evaluate the presence, seasonal variability and impact of plastic additives along the Besos river basin (Catalonia, Spain). This river flows through a highly urbanized and industrialized area with discharge of >25 Wastewater Treatment Plants (WWTPs) and with large amounts of floating plastics. Compounds studied included 5 phthalates, its substitutes acetyl tributyl citrate (ATBC) and bis(2-ehtylhexyl) adipate, 12 long and short chain alkylphenols, bisphenol A and benzophenone, most of them high volume production chemicals. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) was used to determine ng/L concentrations. Toxicity evaluation was performed for each individual compound using Daphnia magna as test organism and it was found that the effect concentration (EC50) decreased with increasing octanol-water partition coefficients. The EC50 values calculated and Measured Environmental Concentrations were used to determine the risk quotients. Only diethylhexylphthalate, nonylphenol and octylphenol, with median concentrations from 41.9 to 826 ng/L, caused a small risk mostly in downstream waters with 50-75% of the samples overpassing the Environmental Quality Standards set by the European Union. Seasonal variations were observed with higher levels in summer due to low water flows. WWTPs effluents and leaching from floating plastics or microplastics were presumably main sources of pollution.

Multiresidue method for the determination of high production volume plastic additives in river waters.

The aim of this study was to develop a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)-based method for the multiresidue analysis of 21 plastic additives in river water. Analysed compounds included phthalates, benzophenone, bisphenol A and long- and short-chain alkylphenols (APs), which are of relevance because most of them are high production volume chemicals largely used in the plastic industry. These compounds can reach river waters due to direct discharge from wastewater treatment plants and leaching from plastic materials and microplastics present in rivers. In a first step, ionisation and acquisition parameters were optimised to obtain high sensitivity and structural information. Then, different solid-phase extraction cartridges and elution conditions were tested using Milli-Q and river water. With the optimised conditions, quality control parameters (recoveries, limits of detection, intra- and inter-day variability and blank contribution) proved that the method was accurate and selective for the trace monitoring of these compounds in river water. For nonylphenol, octylphenol and bis(2-ethylhexyl)phthalate, included in the Water Framework Directive, limits of detection were below environmental quality standard concentrations considering blank contributions. All other compounds were efficiently detected at trace levels, and focus was given to o- and p-substituted and di- and tri-substituted APs, which are first reported in the present study. A pilot survey was finally carried out to determine the occurrence of plastic additives in river waters surrounding the city of Barcelona.

Powerful combination of analytical and chemometric methods for the photodegradation of 5-Fluorouracil.

The photodegradation of the antineoplastic drug 5-fluorouracil (5-FU) under the action of UV light was studied using UV-vis spectroscopy and High Performance Liquid Chromatography coupled to Diode Array Detector and High Resolution Mass Spectrometry (HPLC-DAD-HRMS). To analyze, integrate and interpret the degradation kinetics, the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) chemometric method has been applied. The high complexity of the photodegradation process of this drug involving up to seven different photoproducts showed the advantages of the proposed approach which provides simultaneously mechanistic and structural information explaining the 5-FU photodegradability. Moreover, this study provides a new tool to be used for elucidating the photodegradation kinetics at real time.