@article {293,
	title = {A Rapid Testing Kit for 6PPD Screening in Rubber Products.},
	journal = {Anal Chem},
	year = {2025},
	month = {2025 Apr 26},
	abstract = {<p>-(1,3-dimethylbutyl)--phenyl--phenylenediamine (6PPD) has received increasing attention due to its ubiquitous environmental occurrence and extreme aquatic toxicity of its oxidation product 6PPD-quinone. Given 6PPD{\textquoteright}s application as an antioxidant in a wide array of rubber products, cost-effective detection of 6PPD is important for product and waste management. We herein developed a rapid testing kit for the detection (\&lt;10 min) of 6PPD in rubber products with low costs (\&lt;$1/sample), which was inspired by the observation of a red-colored product after 6PPD exposure to oxidants. The selectivity of this reaction was evaluated by 14 structurally diverse phenols and anilines. Interestingly, the protonated -1,3-dimethyl butyl--phenyl quinone diimine (6QDI+H), rather than its neutral or radical counterparts, appeared to be the red-colored product with λ = 490 nm. We further developed a "green" and user-friendly 6PPD rapid testing kit, which was further applied to a wide array of 50 rubber products. 6PPD was detected in 22 out of 50 samples, with a strong agreement ( = 0.896) observed between the results of the rapid testing kit and LC-MS. In summary, this study introduces a 6PPD rapid testing kit for users without requiring expertise in chemistry.</p>},
	issn = {1520-6882},
	doi = {10.1021/acs.analchem.5c00079},
	author = {Li, Zhuoyuan and Xie, Linna and Nair, Pranav and Yeung, Kirsten and Meek, Oliver and Tao, Juan and Hiki, Kyoshiro and Hao, Chunyan and Peng, Hui}
}
@article {276,
	title = {Structurally Selective Ozonolysis of -Phenylenediamines and Toxicity in Coho Salmon and Rainbow Trout.},
	journal = {Environ Sci Technol},
	year = {2024},
	month = {2024 Nov 23},
	abstract = {<p>The tire-rubber-derived ozonation product of -(1,3-dimethylbutyl)-{\textquoteright}-phenyl--phenylenediamine (6PPD), -(1,3-dimethylbutyl)-{\textquoteright}-phenyl--phenylenediamine-quinone (6PPD-Q), was recently discovered to cause acute mortality in coho salmon (). -Phenylenediamines (PPDs) with variable side chains distinct from 6PPD have been identified as potential replacement antioxidants, but their toxicities remain unclear under environmentally relevant ozone conditions. We herein tested the multiphase gas-surface ozone reactivity of four select PPDs [6PPD, -isopropyl-{\textquoteright}-phenyl--phenylenediamine (IPPD), ,{\textquoteright}-diphenyl--phenylenediamine (DPPD), and -phenyl-{\textquoteright}-cyclohexyl--phenylenediamine (CPPD)] and evaluated the toxicity of their reaction mixtures in coho salmon, rainbow trout (), and fathead minnow (). 6PPD and IPPD were found to rapidly react with ozone, while no significant multiphase ozone reactivity was observed for DPPD or CPPD. The viability of coho salmon CSE-119 cells was strongly affected by the ozonolysis products of 6PPD but not by those of the other three PPDs. Acute mortality was only observed in juvenile rainbow trout that were exposed to oxidized 6PPD, suggesting a common mechanism of toxic action in the two salmonid fish species. This study reports the structurally selective ozone reactivity of PPDs and the unique toxicity of 6PPD ozonolysis mixtures, which demonstrates that other PPDs are potential alternative antioxidants.</p>},
	issn = {1520-5851},
	doi = {10.1021/acs.est.4c04817},
	author = {Xie, Linna and Yu, Jie and Nair, Pranav and Sun, Jianxian and Barrett, Holly and Meek, Oliver and Qian, Xing and Yang, Diwen and Kennedy, Lisa and Kozakiewicz, Derek and Hao, Chunyan and Hansen, John D and Greer, Justin B and Abbatt, Jonathan P D and Peng, Hui}
}
