NOPR Collection:

A sensitive and selective fluorescence sensing of bisphenol A based on magnetic Fe3O4@SiO2@QDs@MIPs nanoparticles

2020-07-28T09:20:52Z

Title: A sensitive and selective fluorescence sensing of bisphenol A based on magnetic Fe3O4@SiO2@QDs@MIPs nanoparticles Authors: Zhang, Yafang; Wei, Xiaolong; Wang, Zhihua Abstract: A flexible magnetic and fluorescent sensing for the recognition and detection of bisphenol A (BPA) based on a hybrid magnetic Fe₃O₄@silica nanoparticle@Mn:ZnS quantum dots@molecularly imprinted polymers nanoparticles (Fe₃O₄@SiO₂@QDs@MIPs NPs) has been designed. Because of the high selectivity of MIPs, the strong fluorescence property of Mn:ZnS QDs, good magnetism of Fe₃O₄ and good water solubility of SiO₂_,the Fe₃O₄@SiO₂@QDs@MIPs NPs can effectively detect BPA effectively in human urine. In the presence of BPA, a new compound is produced via the amino group of Fe₃O₄@SiO₂@QDs@MIPs NPs and the hydroxyl group of BPA, the energy of the QDs is transferred to the compound, which led to fluorescence quenching. The relative fluorescence intensity has decreased linearly with the increasing of BPA concentration in the range 50 to 700 ng/mL and the detection limit is found to be 1.6 ng/mL. In addition, the sensor has shown a strong selectivity with an imprinting factor of 8.7 and distinguished selectivity is also exhibited to BPA over other possibly competing molecules. On the basis of the merits of the Fe₃O₄@SiO₂@QDs@MIPs NPs, the sensor can be applied to detect BPA in human urine sample successfully. Page(s): 887-894

Synthesis and spectral studies of coumarin derivatives as fluorescent probes towards Fe3+ and Cu2+

2020-07-28T09:16:40Z

Title: Synthesis and spectral studies of coumarin derivatives as fluorescent probes towards Fe3+ and Cu2+ Authors: Zhang, Jun; Pang, Zongwen; Dong, Chuan Abstract: Three novel coumarin derivatives have been designed and facilely synthesized, namely 6-[bis-(2-acetoxyethyl)aminomethyl]-4-methyl coumarin (BAMC), 4-(trans-4-methylformate-styryl)-6-[bis-(2-acetoxyethyl) aminomethyl]-coumarin (TSAC) and Trans-4-[2-(benzimidazole-2-substituted)vinyl]-6-methyl coumarin (TBVC). The synthesis route of the coumarin derivatives via various reactions including Pechmann, Wittig and substitution, three strategies are applied in the construction of the coumarin-based fluorescent probes, in view of the impact of the electronic push-pull effect, extended electronic conjugated system, and the strong fluorescence emission group, respectively. The compounds BAMC and TSAC are proved to be selective fluorescent probes to Fe³⁺ and Cu²⁺based on the intramolecular charge transfer mechanism. TBVC exhibits enhanced fluorescent emission in tetrahydrofuran offers the potential for the high-performance fluorescent probe. The relationship between the structure and the fluorescence mechanism of coumarin probes is explored. Page(s): 895-903

Kinetics, isotherms and thermodynamic modelling of reactive blue 52 and reactive orange 107 dyes from aqueous solution using PANI-CoCl2 as adsorbent

2020-07-28T09:14:00Z

Title: Kinetics, isotherms and thermodynamic modelling of reactive blue 52 and reactive orange 107 dyes from aqueous solution using PANI-CoCl2 as adsorbent Authors: Lingeswari, U D; Vimala, T Abstract: In this work decolourisation of organic dyes such as Reactive Blue 52 and Reactive Orange 107 from aqueous solution by PANI-CoCl₂ composite have been studied. Polyaniline (PANI) is a viable conducting polymer because of its unique proton dopability, excellent redox recyclability, chemical stability, variable electrical conductivity, low cost and ease of synthesis. The morphology of PANI-CoCl₂composite have been characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. It is also shown that many factors affected the adsorption rate, such as adsorbent mass, contact time, variation of pH, agitation speed, dye concentration and temperature. The capacity of the adsorbent is tested using recyclability process. Adsorption of Reactive Blue 52 and Reactive Orange 107 by PANI-CoCl₂follows pseudo-second-order kinetics and the best-fit isotherm is the Langmuir model which is confirmed by using correlation coefficients in ANOVA technique. The thermodynamic parameters like changes in free energy, enthalpy and entropy have been also calculated. Page(s): 904-913

Application of adsorptive stripping differential pulse voltammetry with chemometrics in the determination of ascorbic acid, rutin and quercetin in the food and health products

2020-07-28T09:11:48Z

Title: Application of adsorptive stripping differential pulse voltammetry with chemometrics in the determination of ascorbic acid, rutin and quercetin in the food and health products Authors: Zhang, Yue; Li, Fan; Zuo, Junhui; Ni, Yongnian; Qiu, Ping Abstract: The simultaneous determination of ascorbic acid, rutin and quercetin in the food and health products on the glassy carbon electrode have been investigated by adsorptive stripping differential pulse voltammetry (AdSDPV) with the aid of chemometrics. In the pH 5.2 KH₂PO₄– Na₂HPO₄buffer solution, both rutin and quercetin has shown a pair of sensitive reversible oxidation-reduction peak, while ascorbic acid only has shown an irreversible oxidation peak on the glassy carbon electrode. In the range of 0.35-0.50 V, the vlotammograms of three components has shown serious overlap with peak potential of ascorbic acid, rutin and quercetin. So, it is extremely difficult to realize direct measurement for the content of single component. Chemometrics methods have been introduced to determine the admixture of the three components. In this way, we have avoided the troublesome procedures of separation and purification, and assay the artificial compound of the three components all at once. We have estimated the three components in the food and the health products with satisfactory results. Page(s): 914-922