Issue 9, 2001

Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes

Abstract

An electrochemical sensor for the detection of Cu2+ is reported which incorporates poly-l-aspartic acid (PLAsp) with 32–96 aspartate units as a selective ligand for the metal ion. PLAsp is covalently attached to a gold electrode modified with a monolayer of 3-mercaptopropionic acid using carbodiimide coupling via an N-hydroxysuccinimide (NHS) ester intermediate. The acid side groups and deprotonated peptide nitrogens on two aspartate moieties are thought to be primarily responsible for chelation of Cu2+, which remains bound when reduced to Cu+. A consequence of the multiple binding points that are available with a polypeptide is the low detection limit. The lowest concentration detected was 3 nM (0.2 ppb) achieved with Osteryoung square wave voltammetry. This detection limit compares favourably with that of ICP-OES and previously reported cysteine-modified electrodes. Analysis of tap and lake water samples using the PLAsp-modified electrode agreed well with ICP-OES analysis of the same samples.

Article information

Article type
Paper
Submitted
29 Mar 2001
Accepted
29 Jun 2001
First published
16 Aug 2001

Analyst, 2001,126, 1573-1577

Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes

W. Yang, J. J. Gooding and D. B. Hibbert, Analyst, 2001, 126, 1573 DOI: 10.1039/B102898G

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