Search

Because of its widespread distribution in the environment, bisphenol A (BPA) has become a global concern as an endocrine disruptor and a threat to human health through the food chain. Thus an efficient determination method is urgently needed for monitoring the levels of BPA. Herein, a novel electrochemical technique for the detection of BPA was performed by synchronous extraction and pre-concentration of BPA onto magnetic molecularly imprinted polymer (BMMIP), with subsequent readout on a magneto-actuated glassy carbon electrode (MGCE) by differential pulse voltammetry. Compared to the current methods of BPA determination, this BMMIP-based electrochemical sensor (BMMIPs@MGCE) not only simplifies the sample handling procedures substantially, without filtration, centrifugation, or other complex operations, but also can be easily renewed by a controllable magnetic field. As a sensor component, the core–shell BMMIPs exhibited excellent binding capacity (Qe = 82.5 mg g−1), short adsorption equilibrium time (30 s), and outstanding selectivity (k′ = 7.239) towards BPA, as well as stability and recyclability. Importantly, the BMMIPs@MGCE sensor was successfully applied for the on-site monitoring and rapid detection of BPA in complicated real-world specimens, with good recoveries (81.31–119.77%) and a low limit of detection (0.133 μmol L−1). Therefore, the stable and low-cost BMMIPs@MGCE sensor provides a new approach for the rapid determination of BPA in the field of environmental control and food safety. [ABSTRACT FROM AUTHOR]

Abstract A novel magnetic MIPs (DUMIPs) was prepared by surface molecular imprinting method using superparamagnetic core-shell nanoparticle (Fe 3 O 4 @SiO 2) as the sacrificial support matrix, herbicide diuron as template, α-methacrylic acid as the functional monomer, trimethylolpropane trimethacrylate as the crosslinker, azobisisobutyronitrile as the initiator, and acetonitrile as the porogen. Highly cross-linked porous surface and excellent magnetic property were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometer, respectively. The adsorption capacity of DUMIPs was 8.1 mg g−1, 2.6-fold over its corresponding non-imprinted polymers (DUNIPs). The adsorption in DUMIPs was considered as multilayer adsorption and posed high affinity to diuron, due to the better fitting to Freundilich isotherm. Competitive recognition study demonstrated DUMIPs had highly selective binding diuron. DUMIPs, as an influential sorbent has been used for selective extraction of diuron from environmental samples (paddy field water, paddy soil and grain seedlings) and the elution was determined by high efficiency liquid chromatography (HPLC). In this analytical method, various factors affecting the extraction efficiency such as pH, sorbent dosage, utilization efficiency and volumes of eluent were simultaneously investigated. Under the optimal conditions, the linearity of the method obtained is in the range of 0.02–10.0 mg L−1. The limit of detection is 0.012 mg L−1. In four spiked levels (0.04, 0.2, 1.0, and 4.0 mg kg−1), the recoveries of diuron in real samples are in the range of 83.56%–116.10% with relative standard deviations in the range of 1.21–6.81%. Importantly, compared to C 18 -SPE column, the MMIPs exhibited convenient separation by external magnetic field, strong clean-up capacity, and selective enrichment for diuron. Thus, the DUMIPs-based method is great potential for efficient sample preparation in the determination of trace amounts of diuron residues in complex matrices. Graphical abstract Image 1 Highlights • Magnetic separation and surface imprinting were reasonably combined for smart material preparation. • SiO 2 -coated Fe 3 O 4 effectively prevent the agglomerate of magnetic nanoparticles. • The DUMIPs exhibited magnetic properties with specific recognition, high binding capacity, and fast binding kinetics. • The DUMIPs were feasible materials for selective enrichment and efficient separation of diuron from complicated matrices. [ABSTRACT FROM AUTHOR]

Triclosan (TCS) is a kind of chronic toxicity to aquatic organisms. Due to its highly effective antimicrobial, TCS has been widely applied in personal−care products, which naturally poses a potential risk to the ecological system and human health since its release into water−ecological environment. Therefore, it urgently demands a selective, easily separated, recyclable, and low−cost adsorbent to remove the residues of TCS from aquatic environments. In this study, a novel magnetic molecularly imprinted nano−polymers (TMIPs) were prepared for selective adsorption and convenient collection of TCS in aquatic samples, based on a core−shell technique using TCS as template molecule and SiO 2 −coated Fe 3 O 4 nanoparticles as the support substrate. The functional groups, particle size, morphology and magnetic property of TMIPs were characterized by Fourier−transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy and vibrating sample magnetometer, respectively. The obtained TMIPs possessed excellent adsorption capacity (Q e = 53.12 mg g−1), speedy adsorption equilibrium time (2 min) and high selectivity (k' = 6.321) for TCS. Moreover, the pH−tolerance and stability tests manifested that the adsorption capacity of TMIPs for TCS was acid−resistance and could retain 94.2% of the maximum Q e after 5 times removal−regeneration cycles. The feature of magnetically susceptibility can simplify the procedures of sample handling in TCS determination, because the TMIPs of TCS are easy to be recycled from aquatic samples. As an application demonstration, the toxicity test in microalgae confirmed that a tiny amount of TMIPs could significantly eliminate the toxic effect of TCS on Chlamydomonas reinhardtii via the efficient binding with TCS. Image 1 • A kind of nano-polymers with magnetic property and excellent adsorption were prepared by core-shell technique. • The molecularly imprinted nano-materials (TMIPs) have specific binding with triclosan. • High recoveries in spiked aquatic samples proved that the TMIPs were feasible sample handling nanomaterials for rapid enrichment of triclosan. • TMIPs as magnetically recyclable sorbents were successfully applied in the efficient removal of triclosan from aquatic environments. [ABSTRACT FROM AUTHOR]