The combination of a low-pressure mercury lamp and chlorine (UV/chlorine) was applied as an emerging advanced oxidation process (AOP), to examine paracetamol (PRC) degradation under different operational conditions. The results indicated that the UV/chlorine process exhibited a much faster PRC removal than the UV/H₂O₂ process or chlorination alone because of the great contribution of highly reactive species (^•OH, ^•Cl, and ClO^•). The PRC degradation rate constant (k_obs) was accurately determined by pseudo-first-order kinetics. The k_obs values were strongly affected by the operational conditions, such as chlorine dosage, solution pH, UV intensity, and coexisting natural organic matter. Response surface methodology was used for the optimization of four independent variables (NaOCl, UV, pH, and DOM). A mathematical model was established to predict and optimize the operational conditions for PRC removal in the UV/chlorine process. The main transformation products (twenty compound structures) were detected by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS).

A novel method was developed for the sensitive, cheap and fast quantitation of 10 phthalates in non-alcoholic beverages by liquid–liquid extraction (LLE) combined with gas chromatography tandem mass spectrometry (GC-MS/MS). The best results were obtained when n-hexane was used as extraction solvent. A central composite design (CCD) was applied to select the most appreciated operating condition. The method performance was evaluated according to the SANTE/11945/2015 guidelines and was linear in the 0.1 to 200 µg/L range for 10 phthalate compounds, with r² > 0.996 and individual residuals <15%. Repeatability (RSD_r), within-laboratory reproducibility (RSD_wr), and the trueness range were from 2.7 to 9.1%, from 3.4 to 14.3% and from 91.5 to 118.1%, respectively. The limit of detection (LOD) was between 0.5 to 1.0 ng/L and the limit of quantitation (LOQ) was between 1.5 to 3.0 ng/L for all 10 compounds. The developed method was successfully applied to the analysis of non-alcoholic beverages.

The aim of the present study was to investigate the electrochemical formation of active chlorine and its subsequent use for the degradation of the pesticide fenobucarb. Initially, the process of electrochemical active chlorine production was investigated using an electrochemical flow-cell with a Ti/RuO₂ plate electrode. The contribution of four main factors (chloride concentration, current density, the retention time of chloride in the cell (flow rate), and initial pH of inlet solution) to form active chlorine was determined by a central composite design (CCD). The influence of the four variables was statistically significant, and the contributions of flow rate, chloride concentration, pH, and current density were found to be 37.2%, 33.59%, 18.28%, and 10.93%, respectively. A mathematical model was established to predict and optimize the operating conditions for fenobucarb removal in the NaCl electrolysis process. The main transformation products (seven compound structures) were detected by liquid chromatography coupled with high-resolution mass spectrometry (LC–HRMS). The results of the model and transformation products indicated that fenobucarb was degraded due to direct oxidation on the electrode surface, and indirectly by active chlorine and other radicals present during the NaCl electrolysis process.