title: Sorption mechanisms of cephapirin, a veterinary antibiotic, onto quartz and feldspar minerals as detected by Raman spectroscopy.
abstract: Raman spectroscopy was used to investigate sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO(2)) and feldspar (KAlSi(3)O(8)) at different pH. Sorption occurs by electrostatic attraction, monodentate and bidentate complexation. The zwitterion (CHP(o)) adsorbs to a quartz((+)) surface by electrostatic attraction of the carboxylate anion group (-COO(-)) at low pH, but adsorbs to a quartz((-)) surface through electrostatic attraction of the pyridinium cation, and possibly COO(-) bridge complexes, at higher pH. CHP(-) bonds to quartz((-)) surfaces by bidentate complexation between one oxygen of -COO(-) and oxygen from carbonyl of an acetoxymethyl group. On a feldspar((+/-)) surface, CHP(o) forms monodentate complexes between CO, and possible -COO(-) bridges and/or electrostatic attachments to localized edge (hydr)oxy-Al surfaces. CHP(-) adsorbs to feldspar((-)) through monodentate CO complexation. Similar mechanisms may operate for other cephalosporins. Results demonstrate, for the first time, that Raman techniques can be effective for evaluating sorption mechanisms of antibiotics.
authors.affiliation: Department of Geological & Environmental Sciences, Hope College, P.O. Box 9000, Holland, MI 49422-9000, USA. peterson@hope.edu
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Peterson
authors.forename: Theresa A
authors.initials: TA
authors.lastname: O'Meara
authors.forename: Michael D
authors.initials: MD
authors.lastname: Seymour
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Baohua
authors.initials: B
authors.lastname: Gu
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002514:Cephapirin / Q000032:analysis*; D054750:Ecotoxicology / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D017680:Potassium Compounds; D011791:Quartz; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods; D019155:Veterinary Drugs / Q000032:analysis*
chemical_list: D000538:Aluminum Silicates; D000900:Anti-Bacterial Agents; D004785:Environmental Pollutants; D017680:Potassium Compounds; D019155:Veterinary Drugs; C016447:feldspar; D011791:Quartz; D002514:Cephapirin