Investigation of adsorption of nanogram quantities of iron(II) tris-(1,10-phenanthrolinate) on glasses and silica by thermal lens spectrometry

Thermal lens spectrometry is used for studying adsorption equilibria in aqu eous solutions at the level of nanogram quantities of iron(II) tris-(1,10-p henanthrolinate) as a model system. The kinetics of the sorption of the che late on silica is studied and adsorption isotherms are built. Thermal lensi ng is used as a method for direct determination of the chelate concentratio n adsorbed on a quartz surface. The detected amount is 4.1 x 10(-15) mol at the area irradiated by the excitation beam. The adsorption of iron(II) tri s-(1,10-phenanthroiinate) on laboratory glassware at the nanogram level is characterised by measuring the residual concentration of the sorbate in sol ution. A procedure for handling and cleaning the laboratory glassware for d etermining nanogram amounts of iron in aqueous solutions is proposed. The s ensitivity of thermal lensing both in measuring adsorption on silica and gl ass and quartz surfaces is 100-fold higher than diffuse-reflectance measure ments under the same conditions. (C) 2001 Elsevier Science B.V. All rights reserved.