Phenylenediamines and quinone derivatives: analytical advances

Phenylenediamines (PDs) and their N,N′ -substituted derivatives (PPDs) are widely used antiozonants in rubber and polymer manufacturing, with significant release into the environment via tire wear particles. Once emitted, they undergo oxidative transformations, producing quinone derivatives and other products through ozonolysis, photooxidation, and hydrolysis. Among these transformation products, quinone derivatives are the most extensively studied due to their enhanced stability and high toxicity, exemplified by 6PPDQ-induced mortality in coho salmon at ng/L levels. Their occurrence has been reported in water, soils, air, dust, and food products, raising concerns over ecological risks and potential human exposure. This review critically assesses current analytical methodologies, highlighting liquid chromatography–mass spectrometry as the most powerful tools, complemented by tailored extraction approaches such as solid-phase extraction (SPE), liquid–liquid extraction (LLE), Quick, Easy, Cheap, Effective, Rugged, and Safe extraction (QuEChERS), and accelerated solvent extraction (ASE). Despite methodological advances, major challenges persist, including low environmental concentrations, chemical instability, and lack of certified standards. Future priorities include harmonized protocols, interlaboratory validation, and development of emerging analytical and real-time monitoring technologies.