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RECEIVED for review October 2, 1984, Accepted November 26,1984. This work was supported by the National Science Foundation through Grant No. CHE 78-25542 and by the (hduate School of Eastern Michigan University through the Research and Sabbatical Leaves Program.
Performance Studies under Flow Conditions of Silica- Immobilized 8-Quinolinol and Its Application as a Preconcentration Tool in Flow Injection/Atomic Absorption Determinations Monte A. Marshall’ and Horacio A. Mottola*
Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078
The use of silica-lmmoblllred 8-quinolinol prepared by an improved synthetic route has been evaluated as a preconcentratlon material for trace metal Ions In flow systems. Breakthrough capacitles were evaluated under different flow, temperature, and geometric characteristics of the preconceniratlng column. Mass transfer IlmHatlons under flow condltlons explaln the dependence of breakthrough capacltles on these variables. The capabllltles of this material for on-line preconcentration of copper( I I ) using flow Injection analysis (FIA) for sample processlng and atomic absorption spectrometry (AAS) for detection have also been evaluated. The relatively hlgh capaclties of these simply and reproduclbly prepared materials as well as the absence of swelllng complications afforded by the Inorganic slllca framework allow for their effective use In FIA/AAS by Implementation of rather slmple manlfolds. Results obtained for the determlnation of ng/mL levels of copper( I I ) in some EPA water samples agreed very well with reported values.
Bonded silicas, widely used in liquid chromatographic separations, have recently shown recognized potential for sample preconcentration or matrix isolation. The so-called “extraction columns”, employing bonded silicas, have become popular for sample preparation prior to chromatographic separations, virtually replacing the more laborious liquidliquid extraction procedures. In fact, bonded-phase sample preparation has been identified as a growing technological trend (1) and has received prevalent attention for the selective preconcentration of trace metal ions (2-7). The immobilization of reagents on silica supports offers some distinct advantages over immobilization on organic polymer supports. First, the silica is readily modified by a variety of silylating agents allowing for a myriad of functional groups to be immobilized. Second, since the bound group is a t the surface of the support, high exchange rates are generally observed (2, Present address: Monsanto Co., Corporate Research Center, 800
N. L i n d b e r g h Blvd., St. Louis, MO 63167.
4 ) whereas some highly cross-linked organic polymer matrices may require hours for equilibration (8). Third, silica offers excellent swelling resistance with changes in solvent composition having little effect on the support at pH
