A surface-based ammonium ion sensor: An electrode derivatized with a self-assembled monolayer

ANYL 110

Nantanit Wanichacheva, nantanit@wpi.edu1, Sara E. Strecker, streck@wpi.edu1, Ernesto Soto, esoto@wpi.edu2, Christopher R. Lambert, clambert@wpi.edu2, and W. Grant McGimpsey, wgm@wpi.edu1. (1) Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, (2) Department of Chemistry & Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609
Self-assembled monolayers (SAMs) of 11-mercapto-N-(4-(9,15,18-triisopropyl-6,12-dimethyl-2,5,8,11,14,17-hexaoxo-1,7,13-trioxa-4,10,16-triazacyclooctadecan-3-yl)butyl) undecanamide were prepared on gold. Characterization of the SAMs was carried out by sessile drop contact angle, ellipsometry, grazing angle FT-IR spectroscopy and electrochemical techniques. The cation recognition properties of the SAM were studied by cyclic voltammetry and impedance spectroscopy. The films show moderate selectivity for detection of ammonium ions in aqueous solution over potassium and sodium ions, with selectivity values calculated to be log K NH4+,Na+ ~ -1.1 and log K NH4+,K+ ~ -1.2. The selectivity of this sensor for ammonium ions over potassium ions was somewhat higher for this compound than for nonactin (log K NH4+,K+ ~ -0.9), a compound used for detection of ammonium ions in commercial ion selective electrodes. To the best of our knowledge, this is the first demonstration of an ammonium sensor fabricated using self-assembled monolayer technology.
 

General Papers
7:00 PM-9:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster

Division of Analytical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006