Determination of eight ultraviolet absorbers in surface water and wastewater by ultra performance liquid chromatography-triple quadrupole mass spectrometry

Ultraviolet （UV） absorbers are a group of chemicals widely used in various industrial and consumer products， such as plastics， coatings， and personal care products， to protect against UV radiation. Among them， benzotriazole derivatives （e.g. UV-326， UV-327， UV-328， UV-329， and UV-P） are the most frequently employed. Owing to their widespread use and potential persistence in the environment， these compounds have been detected in various environmental matrices， including surface water， wastewater， sediment， and biota. Certain UV stabilizers have been reported to exhibit endocrine-disrupting properties and pose potential ecological risks. Therefore， developing sensitive and reliable analytical methods for monitoring these compounds in environmental samples is essential. To address the need for reliable detection methods， this study developed a robust method based on liquid-liquid extraction （LLE） coupled with ultra performance liquid chromatography-triple quadrupole mass spectrometry （UPLC-MS/MS） for the simultaneous determination of eight UV absorbers in surface water and wastewater. Critical optimization of the pretreatment process focused on solvent selection and purification parameters. The finalized protocol involved extracting 100 mL water samples twice with dichloromethane. After nitrogen-assisted solvent evaporation， the residue was reconstituted in methanol and mixed with the internal standard solution. UPLC-MS/MS parameters were optimized to achieve optimal instrumental performance. The separation of the eight UVs was performed using a BEH C18 column （100 mm × 2.1 mm， 1.7 μm） with a gradient elution system consisting of 0.2% （mass fraction） formic acid aqueous solution and acetonitrile at a flow rate of 0.4 mL/min. The injection volume was 2 μL. Detection was performed in positive ion mode using multiple reaction monitoring （MRM）， with an electrospray ionization voltage set at 5 500 V. Quantification was achieved via internal standard calibration to ensure precision and accuracy. The method demonstrated excellent linearity for all target compounds across their respective concentration ranges， with a correlation coefficient （<italic>r</italic>）&gt;0.995. The method detection limits （MDLs） ranged from 1.3 ng/L to 2.8 ng/L， indicating high sensitivity. Recovery tests conducted at low， medium， and high spiking levels （20， 200， and 800 ng/L） yielded recoveries of 80.3%-117.8%， with relative standard deviations （RSDs） of 1.4%–10.5%， confirming the method’s robustness across different sample matrices. Application of the method to 10 textile dyeing wastewater samples revealed the presence of four UV absorbers： UV-329， UV-326， UV-328， and UV-350. Notably， UV-329 showed the highest detection frequency and accounted for 85% of the total detected mass concentrations， ranging from not detected （ND） to 2 109 ng/L. Its prevalence suggests its widespread use in industrial processes and potential persistence in aquatic environments. In conclusion， the developed method is highly sensitive， accurate， and reliable for detecting UV absorbers in environmental water samples. Its successful application to surface water and wastewater analysis provides a valuable tool for monitoring these emerging contaminants， thereby supporting the assessment of their environmental and health risks. This study highlights the importance of continued monitoring and regulation of UV absorbers to mitigate their potential adverse effects on ecosystems and human health.