Influence of the electrografting method on the performances of a flow electrochemical sensor using modified electrodes for trace analysis of copper (II)

• Influence of the modification process of electrodes on their sensor properties.
• The modified electrodes were characterized by electrochemical analysis and XPS.
• For cyclam-modified electrodes, the signal increased with the surface coverage.
• A more specific receptor enhanced the selectivity of the sensor.
• The nature of the ligand can affect the signal and the selectivity of the sensor.

The performances of carboxylate- and cyclam-modified graphite felt electrodes prepared by different electrografting methods for trace analysis of copper (II) were compared to determine the influence of the immobilization process of the linkers on the sensor properties. The derivatization performed by cathodic reduction of diazonium salts and by anodic oxidation of amines in organic and aqueous media was first evaluated by cyclic voltammetry and X-ray photoelectron spectroscopy analyses, showing a higher surface coverage for the reduction process. Cyclam was subsequently attached on the COOH-modified graphite felts by a coupling reaction. The modified electrodes were then employed in a flow analytical system for trace analysis of copper (II) ions. The influence of the surface coverage and the nature of the linker on the electrochemical signal obtained by linear sweep stripping voltammetry analysis after a preconcentration step performed at open circuit was highlighted. The selectivity estimated in the presence of lead used as a common ion interferent was higher when a selective receptor was used and depends on the nature of the linker.

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