The wide use and continuous abrasion of rubber-related products appears to be leading to an incredible release of p-phenylenediamine (PPD) antioxidants in the environment. However, no related research has been conducted on the pollution characteristics and potential health risks of PM 2.5 -bound PPDs. We report for the first time the ubiquitous distributions of six emerging PPDs and a quinone derivative, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPDQ), in PM 2.5 from urban areas of China. Atmospheric contamination levels of PM 2.5 -bound PPDs were found to be mostly in pg m −3 amounts between 2018 and 2019. Urban vehicle rubber tire abrasion was found to probably contribute to the PPDs in PM 2.5 and accounted for their significant spatiotemporaldependent concentration variations. Furthermore, 6PPDQ, an emerging oxidation product of 6PPD in the environment, was first quantified (pg m −3 ) with a total detection rate of 81% in the urban PM 2.5 , demonstrating its broad existence. On the basis of the determined ambient concentrations, the annual intakes of PPDs and 6PPDQ for adults were not low, indicating their possible human health risks induced by long-term exposure. This study confirms the widespread occurrence of PPDs and 6PPDQ in PM 2.5 , showing that the pollution of such compounds in urban air should not be underestimated.

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To satisfy the requirement of simultaneous extraction and characterization of diverse kinds of multitarget analytes, the preparation, characterization, and application of a novel tetraazacalix[2]arene[2]triazine (TCT) coated magnetic nanoparticle (TCT MNP) adsorbent are presented in this paper. TCT assembles two benzene rings and two triazines with nitrogen cross-bridging links, which exhibits a unique structural framework and versatile recognition features based on the multiple recognition sites. These include π electron stacking, charge transfer, hydrogen bonding, and ion-exchange. TCT MNPs acted as a dispersive SPE adsorbent showing strong interaction with and adsorption of polycyclic aromatic hydrocarbons (PAHs), nitroaromatics, and heavy metal ions. The dispersive magnetic nanoparticle solid phase extraction (d-MNSPE) strategy with the simultaneous extraction and stepwise elution (SESE) procedure was designed and optimized for the five PAHs (phenanthrene, anthracene, pyrene, chrysene, and benzo(a)pyrene), six nitroaromatics (4-nitrotoluene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, 4-nitrophenol, 2,4-dinitrophenol, and 2,4,6-trinitrophenol), and four metal ions (Cu, Zn, Mn, Cd) in aqueous samples. Due to the high stability, desirable durability, larger saturation magnetization, reuse and distinct enrichment capacity of TCT MNPs, the d-MNSPE method with the SESE strategy provided high recovery (>90%) and good precision (relative standard deviations, RSD < 10%). Coupled with the commonly used HPLC-fluorescence detection, HPLC-UV detection, and atomic absorption spectrometry, these trace probes in tap water, river water, and lake water were determined with very low detection limits, in the range of 0.09-0.15 pg mL for PAHs, 6-11 pg mL for nitroaromatics, and 17-53 pg mL for metal ions after being enriched by the d-MNSPE. The determination of trace PAHs in urine samples from smokers and nonsmokers was successfully carried out with this method, which implied that the versatile TCT MNPs and the robust method together represent a significant potential application in the analysis of body fluids and disease markers. Such methods for accurate quantification of trace components in water are very valuable as they fulfill an unmet need in environmental and medicinal chemistry.