Tracking oxytetracyline mobility across environmental interfaces by second harmonic generation

Amanda L. Mifflin, Christopher T. Konek, Franz M. Geiger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


This work examines the binding behavior of the antibiotic oxytetracycline (OTC) to mineral oxide/water interfaces in the presence and absence of organic functional groups using the interface-specific technique second harmonic generation (SHG). Studies show that OTC binding to fused quartz, methyl ester, carboxylic acid, and alkyl interfaces is fully reversible and highly dependent on solution pH, with appreciable adsorption occurring only at pH 8. Relative surface coyerage at pH 8 is highest for the polar organic-functionalized surfaces, and surface saturation occurs for the methyl ester-functionalized fused quartz/water interface at 2 × 10-5 M. Adsorption isotherm measurements indicate that the binding process is controlled by hydrogen bonding and hydrophobic interactions, with free energies of adsorption on the order of -40 kJ/mol for all interfaces studied. The results indicate that OTC transport in the environment will depend heavily on soil pH and composition and have implications for the development of bacterial antibiotic resistance.

Original languageEnglish (US)
Pages (from-to)22577-22585
Number of pages9
JournalJournal of Physical Chemistry B
Issue number45
StatePublished - Nov 16 2006

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


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