Exfoliated Graphite Oxide Modified Electrode for the Selective Determination of Picomolar Concentration of Lead

Abstract

We report the selective, picomolar determination of lead(II) ions using exfoliated graphite oxide (EGO) modified glassy carbon electrode. Exfoliated graphite oxide is the oxidized form of exfoliated graphite containing a variety of functional groups such as hydroxyl, phenolic and carboxyl groups. The EGO can be dispersed as a stable colloid in a wide range of pH, from 2 to 11. This leads to the flexibility of film formation on substrates and use of a variety of functional groups to complex lead ions. The analyte is preconcentrated and subsequently determined using differential pulse anodic stripping voltammetry. The factors influencing the determination of lead such as the pH of the analyte solution, preconcentration time and the thickness of EGO layer on the electrode surface have been optimized. Two linear ranges are observed between 1 mM and 10 mm and 0.1 mM and 1 pM for a 5 minute preconcentration time. The lowest detection limit is found to be 1 pM. The main advantages of the electrode are the ease of preparation of the modified electrode, low cost, sensitivity and selectivity. The analytical utility of the EGO modified electrode in the determination of lead is demonstrated by application to several water samples.

Covalent modification of glassy carbon spheres through ball milling under solvent free conditions: A novel electrochemical interface for mercury(II) quantification

“…The unmodified glassy carbon spheres have revealed the presence of peaks due to -OH and CQO groups of -COOH at 3435 and 1600 cm À 1 , respectively. The peak at 1351 cm À 1 might be due to the stretching of -OH group of phenol, and the peak at 2800 cm À 1 is due to the stretching of aromatic protons which are in good agreement with the reported literature [18]. However, the IR spectrum of the modified glassy carbon spheres showed peaks at 1618 and 3336.4 cm À 1 , revealing the presence of CQO and -NH groups of amide bond.…”

A binderless, covalently bulk modified electrochemical sensor: Application to simultaneous determination of lead and cadmium at trace level

“…However in the subsequent reverse scan, the voltammogram showed two peaks at −0.49 and −0.75 V which corresponds to the reoxidation of lead and cadmium ions, respectively. The redox potential of Pb 2+ is in agreement with the literature [21] and the peaks at −0.87 and −0.75 V might be due to the reduction and oxidation of Cd 2+ ions, respectively. In case of oxidized and modified electrode there is a small increase in the capacitive current when compared to unmodified electrode.…”

“…These observations have revealed that the presence of modifier molecule with suitable functionalities could enhance the electrochemical response for both lead and cadmium ions. This kind of modified electrode behavior might be attributed to the interacting ability of the functional groups i.e., carboxyl and hydroxyl present on the surface of carbon toward lead and cadmium ions present in the electrolyte at the interface [21].…”

“…The oxygen containing functionalities like carboxyl and hydroxyl groups are known to show potential affinity towards metal ions like lead and cadmium [21][22][23]. In the present study, we have used salicylic acid as a modifier molecule and covalently anchored onto the surface of graphitic carbon in bulk quantities through microwave irradiation.…”

Amino-calixarene-modified graphitic carbon as a novel electrochemical interface for simultaneous measurement of lead and cadmium ions at picomolar level

“…Finally, the carbon powder particles were washed with acetone to remove the moisture. The functionalized carbon powder was dried by placing in a fume hood for a period of 10 h and stored in an airtight container prior to its use [44] (Scheme 2).…”