Voltammetric detection of lead(II) and mercury(II) using a carbon paste electrode modified with thiol self-assembled monolayer on mesoporous silica (SAMMS)

• Published in: Analyst (London) Vol. 128; no. 5; pp. 467 - 472
• Main Authors: YANTASEE, Wassana, YUEHE LIN, ZEMANIAN, Thomas S, FRYXELL, Glen E
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.05.2003
• Subjects: Analytical chemistry; Carbon; Chemistry; Electrochemical methods; Electrochemistry - methods; Electrodes; Exact sciences and technology; Lead - analysis; Mercury - analysis; Water Pollutants, Chemical - analysis; Electrode adsorption; Lead ion; Chemical analysis; Electrochemical method; Anodic stripping voltammetry; Carbon electrode; Electrochemical enrichment; Electrochemical storage; Mercury ion; Transition metal Ions; Multicomponent analysis; Preconcentration; Paste electrode; Silica gel; Quantitative analysis; Modified material
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/b300467h

The anodic stripping voltammetry at a carbon paste electrode modified with thiol terminated self-assembled monolayer on mesoporous silica (SH-SAMMS) provides a new sensor for simultaneous detection of lead (Pb2+) and mercury (Hg2+) in aqueous solutions. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the stripping analysis. Factors affecting the performance of the SH-SAMMS modified electrodes were investigated, including electrode activation and regeneration, electrode composition, preconcentration time, electrolysis time, and composition of electrolysis and stripping media. The most sensitive and reliable electrode contained 20% SH-SAMMS and 80% carbon paste. The optimal operating conditions were a sequence with a 2 min preconcentration period, then a 60 s electrolysis period of the preconcentrated species in 0.2 M nitric acid, followed by square wave anodic stripping voltammetry from -1.0 V to 0.6 V in 0.2 M nitric acid. The areas of the peak responses were linear with respect to metal ion concentrations in the ranges of 10-1500 ppb Pb2+ and 20-1600 ppb Hg2+. The detection limits for Pb2+ and Hg2+ were 0.5 ppb Pb2+ and 3 ppb Hg2+ after a 20 min preconcentration period.