Deciphering the Estrogenic Activity of Aqueous Leachates from Elastomers by Effect-Directed Analysis

Area of Science:

• Environmental Chemistry
• Endocrinology
• Analytical Chemistry

Background:

• N,N -substituted p-phenylenediamines (PPD) are common rubber antiozonants.
• Aqueous leachates from elastomer membranes can contain biologically active compounds.
• Estrogenic activity in environmental samples is a growing concern.

Purpose of the Study:

• To identify the specific compound responsible for estrogenicity in elastomer leachates.
• To investigate the transformation products of PPD antiozonants.
• To quantify the contribution of identified compounds to overall estrogenicity.

Main Methods:

• Effect-directed analysis combining high-performance thin-layer chromatography (HPTLC) and planar yeast estrogen screen (p-YES).
• Nontarget screening using liquid chromatography coupled to high-resolution mass-spectrometry (LC-HRMS).
• Identification of compounds via MS2-spectra elucidation and library research.

Main Results:

• 4-hydroxydiphenylamine (4HDPA) and N-phenyl-p-benzoquinone monoimine (QMI) were identified as transformation products.
• QMI transformed into 4HDPA within the yeast estrogen screen (YES) medium.
• 4HDPA was confirmed as the predominant driver (120 ± 30%) of estrogenicity in elastomer leachates.
• 4HDPA was detected in river and stream water at 7–20 ng/L.

Conclusions:

• 4HDPA is a newly identified estrogenic compound originating from PPD antiozonants.
• Transformation processes within the YES medium can influence results for redox-active compounds.
• Elastomer leachates pose an environmental risk due to 4HDPA elution and formation.
• The presence of 4HDPA in surface waters highlights the need for monitoring.