Highly sensitive and selective sensor for sunset yellow based on molecularly imprinted polydopamine-coated multi-walled carbon nanotubes.

Polydopamine (PDA) can be formed by monomeric self-polymerization in water. This convenient behavior was exploited to prepare a molecularly imprinted polymer (MIP) layer on the surface of multi-walled carbon nanotubes (MWCNTs) with sunset yellow (SY) as a template molecule. The prepared nanocomposites were characterized, and their electrochemical behavior towards SY was investigated. Under the optimized conditions, a glassy carbon electrode modified with the imprinted nanocomposite showed a highly selective and ultrasensitive electrochemical response to SY compared with the performance of control electrodes and previously reported electrochemical sensors for SY. The improved behavior of the developed sensor can be attributed to its superficial highly matched imprinted cavities on the excellent electrocatalytic matrix of MWCNTs and the electronic barrier of the non-imprinted PDA to outside molecules. The fabricated sensor expressed a linear relationship to SY concentrations from 2.2nM to 4.64µM with a detection limit of 1.4nM (S/N = 3). The sensor also exhibited excellent selectivity for SY over its structural analogs, good stability, and adequate reproducibility. The prepared sensor was successfully used to detect SY in real spiked samples. This methodology has potential application value and may be readily adapted to design other PDA-based MIP sensors.

Synthesis, properties and application research of atrazine Fe3O4@SiO2 magnetic molecularly imprinted polymer.

INTRODUCTION: Magnetic Fe3O4 nanoparticles were prepared by coprecipitation and then were coated with SiO2 on the surface. MATERIALS AND METHODS: Fe3O4@SiO2 composite microspheres were modified by KH570. Using molecular imprinting technology, atrazine magnetic molecularly imprinted polymer was prepared by using atrazine as template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linkers. The morphology, composition and magnetic properties of magnetic nanoparticles were characterized. The recognition selectivity of polymer was studied for template molecule and simulation by UV spectrophotometry. The adsorption properties and selectivity ability were analyzed by Scatchard analysis. RESULTS: Scatchard linear regression analysis indicated that there are two binding sites of the target molecules. The magnetic molecularly imprinted polymer has been applied to the analysis of atrazine in real samples. CONCLUSION: The results show that: the recovery rates and the relative standard deviation were 94.0∼98.7% and 2.1∼4.0% in corn, the recovery rates and the relative standard deviation were 88.7∼93.5% and 2.8∼7.2% in water.

[Analysis the properties of Cr2O7(2-) adsorption onto functional organic reagent modified nano-SiO2 by flame atomic absorption spectroscopy].

A new type of functional organic reagent modified nano-SiO2 sorbent (Si/ (CH2)3-NH-CO-Ph-CH2-P(C6H5)3 Br) was synthesized by several reasonable organic combination reactions using nano-SiO2, gamma-Aminopropyl triethoxysilane (KH-550) and functional organic reagent (COOH-Ph-CH2-P(C6 H5)3 Br) as raw materials. The prepared new sorbent was characterized by using FTIR, particle diameter and TG. A batch of adsorption experiments was performed to evaluate its adsorption behavior of Cr2O7(2-) by flame atomic absorption spectroscopy (FAAS). The effects of solution pH, shaken time and sorbent amount on the extraction of Cr2O7(2-) from aqueous solutions were studied. Results showed that when under the optimum conditions the solution pH 1, sorbent amount = 0.1 g, and shaken time = 30 min, the adsorption efficiency can be more than 95%. It indicated that this novel sorbent (Si/ (CH2)3-NH-CO-Ph-CH2-P (C6 H5)3 Br) was a solid sorbent being efficient and low-cost, with convenient separation, and can remove trace Cr2 O7(2-) in environmental waste water.

[Analysis of properties of cadmium adsorption onto whisker surface ion-imprinted polymer by inductively coupled plasma atomic emission spectrometry].

A new type of surface ion-imprinted polymer was synthesized in aqueous media with sodium trititanate whisker in the presence of Cd(II), chitosan and gamma-glycidoxypropyl trimethoxysilane (KH-560). A batch of adsorption experiments were performed to evaluate its adsorption of Cd(II) using inductively coupled plasma atomic emission spectrometry (ICP-AES). The factors affecting adsorption capacity, including pH and sorbent amount, were discussed. The adsorption kinetics and adsorption isothermals were also obtained. The Langmuir isotherm can fit in the experimental equilibrium data. Under the optimum conditions, the value of the adsorption was above 99%, and the maximum adsorption capacity was 52.34 mg x g(-1). In accordance with the parameters distribution coefficient (K(d)) and selectivity coefficient (K), the selectivity for Cd(II) of the prepared imprinted polymer was estimated. Finally, the adsorption mechanism was discussed and the detection limit of 0.024 microg x mL(-1) with the relative standard deviation (RSD) of 1.74% (c = 1.0 microg x mL(-1), n = 13) for Cd(II) was obtained. Results showed that the surface Cd(II)-imprinted polymer was a solid sorbent with high efficiency, low-cost, convenient separation/enrichment for environmental trace Cd(II).