Abstract
Heavy metal pollution can be toxic to humans and wildlife, thus it is of great significance to develop rapid and sensitive methods to detect heavy metal ions. Here, a novel type of electrochemical sensor for the simultaneous detection of heavy metal ions has been prepared by using poly(l-glutamic acid) (PGA) and graphene oxide (GO) composite materials to modify the glassy carbon electrode (GCE). Due to the good binding properties of poly(l-glutamic acid) (PGA) for the heavy metal ions (such as Cu2+, Cd2+, and Hg2+) as well as good electron conductivity of graphene oxide (GO), the heavy metal ions, Cu2+, Cd2+, and Hg2+ in aqueous solution can be accurately detected by using differential pulse anodic stripping voltammetry method (DPASV). Under the optimized experiment conditions, the modified GCE shows excellent electrochemical performance toward Cu2+, Cd2+, and Hg2+, and the linear range of PG/GCE for Cu2+, Cd2+, and Hg2+ is 0.25–5.5 μM, and the limits of detection (LODs, S/N ≥ 3) Cu2+, Cd2+, and Hg2+ are estimated to be 0.024 μM, 0.015 μM and 0.032 μM, respectively. Moreover, the modified GCE is successfully applied to the determination of Cu2+, Cd2+, and Hg2+ in real samples. All obtained results show that the modified electrode not only has the advantages of simple preparation, high sensitivity, and good stability, but also can be applied in the field of heavy metal ion detection.
Highlights
With the development of industry and agriculture, a large amount of heavy metal ions are discharged into the ecological environment
We prepared a novel type of electrochemical sensor for the simultaneous detection of heavy metal ions Cu2+, Cd2+, and Hg2+, which was constructed through using poly(L-glutamic acid) (PGA) and graphene oxide (GO) composite materials to modify the glassy carbon electrode (GCE)
On the surface of PG lms, approximate uniform surfaces without macroscopic phase separation can be observed (Fig. 1C), indicating that they are well composited. This may be due to the strong interactions between some polar groups in GO and PGA chains
Summary
As a representative of 2D carbon materials, graphene oxide (GO) has been widely used to detect heavy metal ions in electrochemical analysis region.7b,8,10 This is mainly due to its good hydrophobicity, moderate conductivity, high chemical stability and excellent electrochemical properties, which is bene cial to improve the detection effect. We prepared a novel type of electrochemical sensor for the simultaneous detection of heavy metal ions Cu2+, Cd2+, and Hg2+, which was constructed through using poly(L-glutamic acid) (PGA) and graphene oxide (GO) composite materials to modify the glassy carbon electrode (GCE). Interest of the constructed electrochemical sensor originated from the following criteria: the ability to bind heavy metal ions with poly(L-glutamic acid) (PGA) due to many carboxyl groups on the side chain of PGA, the conductivity and chemical stability of GO, and their easy preparation and low-cost. The modi ed electrode can be used for the content analysis of Cu2+, Cd2+, and Hg2+ in practical samples, which can be a promising electrode for practical applications in heavy-metal-ion detection
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