Combined effects of pH and dissolved organic matter on the availability of pharmaceuticals and personal care products in aqueous environment

Huazhi Aolin; Lanxue Qin; Sihan Zhu; Xialin Hu; Daqiang Yin

doi:10.1016/j.scitotenv.2024.172637

Combined effects of pH and dissolved organic matter on the availability of pharmaceuticals and personal care products in aqueous environment

Sci Total Environ. 2024 Jun 15:929:172637. doi: 10.1016/j.scitotenv.2024.172637. Epub 2024 Apr 23.

Authors

Huazhi Aolin¹, Lanxue Qin¹, Sihan Zhu¹, Xialin Hu², Daqiang Yin¹

Affiliations

¹ Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
² Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China. Electronic address: xlhu@tongji.edu.cn.

PMID: 38663604
DOI: 10.1016/j.scitotenv.2024.172637

Abstract

The interaction between pharmaceuticals and personal care products (PPCPs) with dissolved organic matter (DOM) can alter their bioavailability and toxicity. Nevertheless, little is known about how pH and DOM work together to affect the availability of PPCPs. This study investigated the impact of pH and DOM on the availability of seven PPCPs, namely Carbamazepine, Estrone, Bisphenol A, Testosterone Propionate, Triclocarban, 4-tert-Octylphenol and 4-n-Nonylphenol, using negligible depletion solid-phase microextraction (nd-SPME). The uptake kinetics of PPCPs by the nd-SPME fibers increased proportionally with DOM concentrations, likely due to enhanced diffusive conductivity in the unstirred water layer. At neutral pH, the partitioning coefficients of PPCPs for Humic Acid (log K_DOC 3.87-5.25) were marginally higher than those for Fulvic Acid (log K_DOC 3.64-5.11). Also, the log K_DOC values correlated linearly with the log D_OW (pH 7.0) values of PPCPs, indicating a predominant role for hydrophobic interactions in the binding of DOM and PPCPs. Additionally, specific interactions like hydrogen bonding, π-π, and electrostatic interactions occur for certain compounds, influenced by the polarity and spatial conformation of the compounds. For these ionizable PPCPs, the log D_DOC values exhibit a strong dependence on pH due to the dual influence of pH on both DOM and PPCPs. The log D_DOC values rose from pH 1.0 to 3.0, peaked at pH 5.0 to 9.0, and then (sharply) declined from 11.0 to 13.0. The reasons are that in strong acidic circumstances, the coiled and compressed shape of DOM inhibits the hydrophobic interaction, whereas in strong alkaline conditions, significant electrostatic repulsion reduces the sorption. This study reveals that the effects of DOM on the bioavailability of PPCPs are dependent on both pH and the specific compound involved.

Keywords: Bioavailability; Fulvic acid; Humic acid; Interaction; Negligible depletion solid-phase microextraction; Partitioning coefficients.

MeSH terms

Cosmetics* / analysis
Humic Substances / analysis
Hydrogen-Ion Concentration
Pharmaceutical Preparations / analysis
Pharmaceutical Preparations / chemistry
Solid Phase Microextraction
Water Pollutants, Chemical* / analysis
Water Pollutants, Chemical* / chemistry

Substances

Water Pollutants, Chemical
Pharmaceutical Preparations
Cosmetics
Humic Substances