ABSTRACT
A sensor was developed for the first time based on polydopamine nanospheres doped with I2, I-, and IO3- species (PDA-Iodine), to determine the concentration of p-aminophenol (p-AP), phenol (Ph), and p-nitrophenol (p-NP) simultaneously. These polymeric nanospheres were successfully characterized using a variety of techniques including field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, Raman spectroscopy, and X-ray diffraction analysis. A carbon paste electrode was modified with the PDA-Iodine (CPE/PDA-Iodine). Because of the electrocatalytic activity of DA/DQ, I2 and I- species (in the structure of PDA-Iodine), CPE/PDA-Iodine shows enhancement in the electrooxidation peak currents as well as slight negative shift in peak potentials of p-AP, Ph, and p-NP compared with a bare carbon paste electrode. Under optimal experimental conditions, the linear calibration plots are linear in the ranges 0.5-120 µM for p-AP, 0.7-120 µM for Ph, and 1.0-100 µM for p-NP with limits of detection of 30, 40, and 80 nM for p-AP, Ph, and p-NP, respectively (S/N = 3). To prove the performance of the method, the repeatability of the signals of CPE/PDA-Iodine was evaluated and the RSD values obtained were 2.9%, 3.2%, and 3.1% for p-AP (45 µM), Ph (40 µM), and p-NP (40 µM), respectively. The CPE/PDA-Iodine is a promising new sensor for sensing p-AP, Ph, and p-NP simultaneously in tap and river water sample and the values of recoveries for spiked samples were in the range 94.0-104.4%.
Subject(s)
Iodine , Nanospheres , Aminophenols , Carbon/chemistry , Electrochemical Techniques/methods , Iodides , Nitrophenols , Phenol , PhenolsABSTRACT
Two dimensional single-crystal hexagonal gold nanosheets (SCHGNSs) were prepared by microwave heating of a solution of HAuCl4 in an ionic liquid. The SCHGNSs were characterized by field emission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy and electrochemical impedance spectroscopy. The SCHGNSs were then used to modify a graphite paste electrode for voltammetric determination of the hypertension drug captopril (CAP). The modified electrode showed a well-defined oxidation peak (at 0.41 V vs. Ag/AgCl) at pH 7.0 using differential pulse voltammetry. Under the optimum conditions, the response is linear in the 2-400 nM and 4.0-50 µM CAP concentration range, and the detection limit (at S/N = 3) is 0.3 nM. The sensor was successfully applied to the determination of CAP in pharmaceutical tablets and in spiked urine. Graphical abstract Schematic presentation of the preparation of single crystal hexagonal gold nanosheets and their use to modify a carbon paste electrode for ultra-trace voltammetric determination of the drug captopril.
