Thiacalix[4]arene-based complex with Co(II) ions as electrode modifier for simultaneous electrochemical determination of Cd(II), Pb(II), and Cu(II)

A complex [Co-4(TCTA)(2)(H2O)(8)]center dot 10H(2)O (Co-TCTA) based on thiacalix[4]arene derivative has been synthesized for the first time using the solvothermal method. The glassy carbon electrode (GCE) modified with Co-TCTA (Co-TCTA/GCE) could simultaneously determine Cd2+, Pb2+, and Cu2+ at around - 0.75 V, - 0.60 V, and - 0.10 V (vs. ref. Ag/AgCl) and had good stability, selectivity, and reproducibility with relative standard deviation (RSD) of 4.4% for Cd2+, 1.4% for Pb2+, and 5.4% for Cu2+. Co-TCTA/GCE showed wide linear range of 0.4-8.0 mu M for Cd2+, 0.4-7.0 mu M for Pb2+, and 0.6-6.0 mu M for Cu2+ when three ions were determined simultaneously. The limits of detection (LODs) of Cd2+, Pb2+, and Cu2+ were 0.071 mu M, 0.022 mu M, and 0.021 mu M, respectively. Moreover, the sensor was used to determine three ions in lake water sample with satisfactory recoveries of 93.6-93.8% for Cd2+, 93.8-103.3% for Pb2+ and 94.6-95.3% for Cu2+. The good adsorption capacity of Co-TCTA and Co(II)/Co(0) circular mechanism on the surface of the electrode were proposed to enhance the electrochemical signals. This work enriched the theoretical research on the complexes for the determination of heavy metal ions.

Automated summary

A complex material based on a thiacalix[4]arene derivative has been successfully synthesized using the solvothermal method. This material, when modified on a glassy carbon electrode, can simultaneously determine the concentrations of Cd2+, Pb2+, and Cu2+ ions with good stability and selectivity. The material also showed satisfactory results when applied to lake water samples.