Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes
Yang, Wenrong, Gooding, J. Justin and Hibbert, D. Brynn 2001, Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes, Analyst, vol. 126, no. 9, pp. 1573-1577, doi: 10.1039/B102898G.
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Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes
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Redox voltammetry of sub-parts per billion levels of Cu2+ at polyaspartate-modified gold electrodes
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.
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