Fabrication of an electrochemical sensor based on metal-organic framework ZIF-8 for quantitation of silver ion: optimizing experimental conditions by central composite design (CCD)
The ZIF-8 was synthesized and carbon paste electrode (CPE) modified with this metal-organic framework utilized for quantitation of silver(Ι) by differential pulse anodic stripping voltammetry (DPASV) technique. The prepared ZIF-8 and matrix of the electrodes were distinguished by impedance spectroscopy (EIS), XRD, FT-IR, cyclic voltammetry (CV), and SEM/EDX methods. To obtain the strongest stripping peak currents, several significant variables were optimized with response surface methodology (RSM), including ligand amount (near 11% w/w), applied potential for preconcentration (approximately -1.36 V), pH of preconcentration solution (about 8.5) and preconcentration time (about 275 s). A calibration curve was acquired in the limits from 1.0×10−10 to 5.0×10−7 M with the Pearson correlation coefficient R = 0.9993. The limiting detectable concentration (LDC) was distinguished to be 1.0×10−11 M. The developed sensor has high selectivity against mercury (II). The excellent pH, potential and especially size-exclusion based selectivity of the prepared sensor is a unique characteristic that is very important in the determination of silver ion. The developed method was effectively employed for the quantitation of silver (Ι) ion in environmental and industrial samples.