Development and Characterization of Colloidal Gold‐Cysteamine‐Carbon Paste Electrodes

Abstract

The optimal conditions for the preparation of colloidal gold‐carbon paste electrodes (CPEs) by using CPEs modified with cysteamine (Cyst) are discussed. Cysteamine modified‐CPEs (Cyst‐CPEs) were prepared by immersion in a Cyst solution, the experimental variables involved in this modification process being optimized. Different colloidal gold deposition methods on the Cyst‐CPEs were evaluated by recording cyclic voltammograms of methionine solutions. Better electrochemical responses were found for colloidal gold‐Cyst‐CPEs (nAu‐Cyst‐CPEs) prepared by immersion of Cyst‐CPEs in a colloidal gold suspension for 4 hr. Optimization of the different experimental variables involved (colloidal particle size and time of immersion) was also carried out. The surface of nAu‐Cyst‐CPEs was characterized by SEM, and the gold coating electrochemically tested. A surface coverage, Γ, of 3.07 × 10⁻¹⁰ mol cm⁻² was obtained. The analytical suitability of nAu‐Cyst‐CPEs was verified by testing the voltammetric behavior of several compounds with sulfur atoms.

Keywords:

• Colloidal gold
• Carbon paste
• Cysteamine
• Sensors

Acknowledgments

Financial support from the Ministerio de Ciencia y Tecnología (Projects BQU 2001–2050 and BQU 2003–00365), and DANONE‐UCM Project No PR248/02–11716 are gratefully acknowledged.