title: A simple method for estimating surfactant impurities in solvents and subphases used for monolayer studies.
abstract: It is important to assess levels of surface active impurities in solutions used for characterization of monomolecular films and for deposition of Langmuir-Blodgett multilayers. Traditional surface pressure-area measurements lack sufficient sensitivity because of the extremely low surface pressures surfactants exhibit below the formation of a coherent film. In contrast, surface potential measurements at the gas-liquid interface increase in a surfactant-dependent manner in the gaseous-liquid expanded transition region. Using this property of such films together with area reduction, levels of impurities representing less than or equal to 0.1% of a typical coherent monolayer can be quantitated. The measurement does not require ultrapure reference materials and can be performed on a solution immediately before spreading and compression of an experimental monolayer film.
authors.affiliation: Hormel Institute, University of Minnesota, Austin 55912.
authors.forename: J M
authors.initials: JM
authors.lastname: Smaby
authors.forename: H L
authors.initials: HL
authors.lastname: Brockman
mesh_terms: D008081:Liposomes; D008564:Membrane Potentials; D010713:Phosphatidylcholines / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods; D012997:Solvents; D013501:Surface-Active Agents / Q000032:analysis*
chemical_list: D008081:Liposomes; D010713:Phosphatidylcholines; D012997:Solvents; D013501:Surface-Active Agents