title: Laser desorption 7.87 eV postionization mass spectrometry of antibiotics in Staphylococcus epidermidis bacterial biofilms.
abstract: This paper describes the development of laser desorption 7.87 eV vacuum UV (VUV) postionization MS to detect antibiotics within intact bacterial colony biofilms. As >99% of the molecules ejected by laser desorption are neutrals, VUV photoionization of these neutrals can provide significantly increased signal as compared to the detection of directly emitted ions. Postionization with VUV radiation from the molecular fluorine laser single photon ionizes laser desorbed neutrals with ionization potentials below the 7.87 eV photon energy. Antibiotics with structures indicative of sub-7.87 eV ionization potentials were examined for their ability to be detected by 7.87 eV laser desorption postionization MS. Tetracycline, sulfadiazine, and novobiocin were successfully detected neat as dried films physisorbed on porous silicon oxide substrates. Tetracycline and sulfadiazine were then detected within intact Staphylococcus epidermidis colony biofilms, the former with LOD in the micromolar concentration range.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607-7061, USA.
authors.forename: Gerald L
authors.initials: GL
authors.lastname: Gasper
authors.forename: Ross
authors.initials: R
authors.lastname: Carlson
authors.forename: Artem
authors.initials: A
authors.lastname: Akhmetov
authors.forename: Jerry F
authors.initials: JF
authors.lastname: Moore
authors.forename: Luke
authors.initials: L
authors.lastname: Hanley
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis*; D018441:Biofilms; D008855:Microscopy, Electron, Scanning; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013212:Staphylococcus epidermidis / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D000900:Anti-Bacterial Agents