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A poly(toluidine blue) modified glassy carbon electrode (PTB/GCE) was prepared by two-step electropolymerization, and was used for the stripping voltammetric analysis of trace uranium for the first time. The results showed that the PTB modified electrode had higher sensitivity of uranium detection compared with the glassy carbon electrode, and the standard addition method was satisfactory for seawater, river water and tap water. The PTB/GCE can be used as a mercury-free electrode for the electrochemical detection of uranyl ions in the environmental water, which provides a new way for the rapid detection of trace uranium. [ABSTRACT FROM AUTHOR]

New insights are proposed into enhancing detection of uranyl ions (UO22+) by electropolymerization brilliant cresyl blue–modified glassy carbon electrode (PBCB/GCE). The mercury-free PBCB/GCE sensor was applied to determine UO22+ in water samples by differential pulse adsorptive stripping voltammetry (DPAdSV). The unique combination of the PBCB/GCE and DPAdSV significantly improves sensitivity due to the polymer of high electroactive area and fast electron transfer rate. The DPAdSV current using a 3 mm diameter PBCB/GCE was proportional to the UO22+ concentration in the range 2.0–90.0 μg·L−1 (− 0.113 V vs. SCE) with a detection limit of 0.650 μg·L−1, RSD = 3.1% (n = 10), and 4.5% reproducibility. In addition, the sensitivity for UO22+ determination was further improved at using an 1 mm diameter PBCB/GCE, which enhances the efficiency of UO22+ deposition due to its higher current density. The 1 mm diameter PBCB/GCE based on DPAdSV technique could be used to determine uranyl ions in the concentration range 0.20–2.0 μg·L−1 (− 0.113 V vs. SCE) with a detection limit of 0.067 μg·L−1, RSD = 5.7 % (n = 10) and 5.4% reproducibility. Hence, the PBCB/GCE is a suitable candidate to substitute the mercury electrode. [ABSTRACT FROM AUTHOR]

Herein, a novel strategy for sensitive determination of uranium in natural water was proposed using electropolymerization of Nile blue modified glassy carbon electrode (PNB/GCE) and differential pulse adsorptive stripping voltammetry (DPAdSV). The preparation of modified electrodes, electrolyte, reproducibility, and substance interferences was studied. The PNB/GCE were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and DPAdSV. The DPAdSV peak current was proportional to the concentration of uranium in the range of 0.30–100 μg·L−1 with the detection limit of 0.19 μg·L−1 and R2 = 0.997. Finally, the PNB/GCE was successfully applied to determination of uranium in natural water samples. [ABSTRACT FROM AUTHOR]

Direct and rapid determination of trace amounts of uranium in natural water remains a challenge. Herein, determination of uranium by differential pulse adsorptive stripping voltammetry (DPAdSV) in presence of cupferron and diphenylguanidine on glassy carbon electrode was investigated. Under optimized conditions, the DPAdSV peak current was proportional to the concentration of uranium in the range of 3–80 μg L−1 with the detection limit of 1.0 μg L−1 and a linear correlation coefficient of 0.999. The DPAdSV method based on GCE was successfully applied to direct determination of trace uranium in natural water samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Neutral red electropolymerized in acid-doped ternary deep eutectic solvents (DES) • Ternary DES composed of choline chloride with ethylene glycol and/or fructose. • Electrochemical, impedance and microscopic evaluation of polymer-film modifiers. • Optimised modified electrode sensors with carbon nanotubes and polymer film. • Sensor applied to determination of acetaminophen by oxidation in aqueous solution. A new electrochemical sensor based on a neutral red (NR) and multiwalled carbon nanotubes (CNT) modified glassy carbon electrode (GCE) with NR electropolymerized in ternary deep eutectic solvents (DES), has been developed. Cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy were used to characterize the performance of the sensor. Differential pulse voltammetry was utilized to evaluate the analytical performance of acetaminophen (APAP) oxidation on the modified electrode (PNR/CNT/GCE) in Britton-Robinson buffer aqueous solution. The combined use of PNR prepared by electropolymerization in novel green DES on CNT led to a large electroactive surface area and a synergistic effect attributed to π–π electronic interactions and resulted in improved performance towards APAP detection, with a high sensitivity (56.4 µA µM−1 cm−2) in the range 2.0–70 µM and a low limit of detection (0.015 µM). The constructed sensor displayed outstanding selectivity to detect APAP in the presence of dopamine, and good repeatability, reproducibility and stability. The sensor was successfully applied to the determination of APAP in pharmaceutical samples, with good recoveries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Brilliant cresyl blue and neutral red electropolymerised in deep eutectic solvents. • Electropolymerisation done in binary and ternary deep eutectic solvents (DES) • DES were choline chloride with ethylene glycol, urea, fructose, oxalic acid. • H-bond donors, acid dopant, carbon nanotube roles on polymer film behaviour probed. • Sensor characteristics tested with ascorbate oxidation in aqueous solution. Brilliant cresyl blue (BCB) and neutral red (NR) have been electropolymerized in binary and ternary deep eutectic solvents (DES) on glassy carbon electrodes (GCE) modified with multiwalled carbon nanotubes (CNT). The influence of binary and ternary DES composition on the polymer film properties was evaluated. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterise the PBCB and PNR films. PBCB/CNT/GCE and PNR/CNT/GCE platforms with polymer formed in ternary DES led to an improvement of the electrochemical properties of the modified electrodes compared to polymer synthesised in the corresponding binary DES. The second hydrogen bond donor tuned the DES characteristics, leading to a sensor platform with higher sensitivity. The PNR/CNT/GCE prepared in different binary and ternary DES were successfully tested for ascorbate sensing and demonstrated the applicability of the sensor architectures. [ABSTRACT FROM AUTHOR]

[Display omitted] • • An electrochemical method was used to extract Sr2+ via an asymmetric pulsed current-assisted technology. • • A novel composite electrode for Sr2+ adsorption was prepared by covalent grafting crown ether derivative. • • This method presented satisfactory Sr2+ extraction performance. • • The adsorbed Sr2+ ions can be desorbed by applying a positive voltage without eluent. In this paper, 4′-aminobenzo-18-crown-6 ether was grafted onto the surface of carbon felt via a diazotization reaction, and a composite material (CE@CF) was obtained. Then, CE@CF was used as an electrode to extract Sr2+ from aqueous solutions and simulated seawater by an asymmetric pulsed current-assisted electrochemical (AP-CE) method. Due to the excellent conductivity of carbon felt and the selectivity of crown ether molecules, the CE@CF electrode exhibited excellent electrochemical extraction performance. Under the optimal alternating potential, the maximum removal efficiency and maximum adsorption capacity of Sr2+ reached 99.5% and 668.9 mg g−1, respectively. The Sr2+ ions adsorbed on the surface of the CE@CF electrode could be desorbed by applying a positive voltage without an eluent, and the CE@CF electrode displayed good recyclability. This work provides an effective strategy for developing covalently-decorated crown ether carbon felt electrodes. The AP-CE method is of great significance for the selective electrosorption of metal ions. [ABSTRACT FROM AUTHOR]