Analytical approaches for detecting biocides in aquatic environments: Advances and challenges

Biocides are chemical substances used to protect humans and animals from harmful organisms such as insects, rodents, algae, fungi, and bacteria. Due to their widespread application in domestic, industrial, and professional settings, biocides are usually detected in aquatic environments, including surface waters, wastewaters and seawaters. Their environmental presence raises concerns related to ecotoxicity, persistence, bioaccumulation, and the development of microbial resistance. This review provides a comprehensive overview of analytical approaches, over the last two decades, for detecting/quantifying major classes of biocides-including disinfectants, preservatives, antifouling agents, and pesticides-in aquatic environments. Sampling strategies were evaluated for their effectiveness in maintaining analytes stability across complex environmental matrices. Key sample preparation methods include traditional techniques such as solid-phase extraction (SPE) and liquid-liquid extraction (LLE), as well as emerging green and miniaturized alternatives like solid phase microextraction (SPME) and dispersive microextraction liquid-liquid (DLLME). Instrumental analysis is predominantly conducted using chromatographic methods coupled with mass spectrometry-gas chromatography-mass spectrometry (GC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) providing high sensitivity and specificity for trace-level detection in aquatic environments. The review highlights the importance of selecting analytical workflows tailored to specific biocide classes across various water types. • Detection and quantification of biocides in aquatic environments are challenging due to complex matrices and low analyte concentrations. • The absence of standardized analytical protocols limits data comparability across regions. • Multi-residue analysis is difficult because of the wide range of biocide polarities. • Rigorous method validation is essential to ensure analytical accuracy and reliability.