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In this study, a simple electrochemical sensor based on l -arginine membrane (P-L-arg/GCE) was developed for rapid and sensitive detection of MDMA and MDA. A polyarginine membrane was obtained through one-step direct electropolymerization, which provides more reaction sites for the analyte and improves the sensitivity of the sensor. Following the optimized selection parameters, the MDMA detection range was established at 1.0 × 10−7∼3.5 × 10−5 mol L−1, with a detection limit of 3.3 × 10−8 mol L−1. Similarly, the detection range for MDA was established at 1.0 × 10−7∼5.3 × 10−5 mol L−1 with a detection limit of 3.3 × 10−8 mol L−1. Additionally, the potential oxidation mechanism of MDMA and MDA during the REDOX process was analyzed by cyclic voltammetry. Furthermore, the proposed sensor exhibited superior selectivity, excellent reproducibility, and satisfactory stability. The proposed sensors can be used for reliable monitoring of MDMA or MDA in human urine and hair samples, respectively, and it has acceptable analytical reliability and enormous potential for practical applications. A simple and highly sensitive electrochemical technique has been developed to quantitatively detect MDMA and MDA using P-L-arg/GCE. By means of this sensor, the electrochemical characteristics of both analytes were thoroughly investigated. The sensor demonstrates sound selectivity, repeatability, and long-term stability in the detection of MDMA and MDA. Furthermore, the method can be applied to the determination of MDMA and MDA in human urine and blood samples. [Display omitted] • A high-sensitive sensor for trace detection of ecstasy was designed. • The possible mechanisms of MDMA and MDA were deduced. • The sensor exhibited a wide detection range and low detection limit. • The sensor was successfully applied to the detection of MDMA and MDA in human serum. [ABSTRACT FROM AUTHOR]

[Display omitted] Overexploitation of nature by humans has led to an increasingly serious issue of heavy-metal water pollution. To reduce the threat of water pollution to humans and the environment, it is imperative to develop or improve the water treatment technology for heavy-metal-containing wastewater. Functionalized Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 MNPs) have been widely used as effective adsorbents for the removal of heavy-metal ions from water owing to their high efficiency, low cost, selective adsorption ability, and recyclability. In this study, Fe 3 O 4 @DA-DMSA magnetic nanoparticles (FDDMs) were prepared by the functionalization of Fe 3 O 4 MNPs with environmentally friendly dopamine (DA) and a heavy-metal detoxifying agent such as 2,3-dimercaptosuccinic acid (DMSA) for the efficient and rapid adsorption of Pb2+, Cu2+, and Cd2+, with maximum adsorption capacities of 187.62, 63.01, and 49.46 mg/g, respectively. FDDMs exhibited the best ability to remove Pb2+ with a maximum adsorption capacity than that of the most reported Fe 3 O 4 MNP-related adsorbents. In actual wastewater and multi-component simulated water samples contaminated with Pb2+, Cu2+, and Cd2+, the as-prepared adsorbent maintained a good removal ability for Pb2+ with low influence by ionic strength and interfering ions, as well as exhibited an excellent selectivity. According to the results of batch experiments and X-ray photoelectron spectroscopy (XPS) analysis of the adsorbent before and after adsorption, the adsorption mechanism of the adsorbent for the removal of heavy-metal ions mainly involves coordination and ion exchange. In addition, the adsorbent exhibited a good regeneration performance. Therefore, FDDMs can be considered as a promising adsorbent for the treatment of heavy-metal wastewater. [ABSTRACT FROM AUTHOR]