Pure and Antimony-doped Tin Oxide Nanoparticles for Fluorescence Sensing and Dye Degradation Applications.

Luminescent antimony doped tin oxide nanoparticles have drawn tremendous attention from researchers due to its low cost, chemical inertness and stability. Herein, a quick, facile and economic hydrothermal/solvothermal method was utilized for the preparation of antimony doped (1%, 3%, 5%, 7% and 10%) tin oxide nanoparticles. The antimony doping in a reasonable range can change the properties of SnO2. As such, a lattice distortion increases with increase in doping, which is evidenced through crystallographic studies. It was found that the highest photocatalytic degradation efficiency of malachite green (MG) dye of about 80.86% was achieved with 10% Sb-doped SnO2 in aqueous media due to small particle size. Moreover, 10% Sb-doped SnO2 also showed the highest fluorescence quenching efficiency of about 27% for Cd2+ of concentration 0.11 µg/ml in the drinking water. The limit of detection (LOD) comes out as 0.0152 µg/ml. This sample selectively detected the cadmium ion even in the presence of other heavy metal ions. Notably, 10% Sb-doped SnO2 could appeared as a promising sensor for fast analysis of Cd2+ ions in real samples.

A Novel Method for the Synthesis of MOF-199 for Sensing and Photocatalytic Applications.

Multifunctional Cu (II)-based Metal Organic Framework (MOF) [Cu3(BTC)2] has been synthesized by a facile electrochemical method. Crystallographic and morphological characterizations of synthesized MOF have been done using Powder X-ray Diffractometer and Scanning Electron Microscope (SEM), respectively, whereas Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDS), UV-Vis Absorption Spectroscopy and Energy Resolved Luminescence Spectroscopic studies have been used for the detailed qualitative, quantitative as well as optical analyses. Sharp PXRD peaks indicate the formation of highly crystalline MOF with face centered cubic (fcc) structure. Flakes (average length = 0.71 µm and width = 0.10 µm) and rods (average aspect ratio = ((0.1:8.3) µm) like morphologies have been observed in SEM micrographs. The presence of C, O and Cu has been confirmed by EDS analysis. Photocatalytic activity potential of the synthesized MOF has been tested using methylene blue dye (MB) as a test contaminant in aqueous media under sunlight irradiation. Selective and sensitive fluorescent sensing of different Nitroaromatic compounds (NACs) like 4-Nitroaniline (4-NA), 2-Nitroaniline (2-NA), 3-Nitroaniline (3-NA), 4-Nitrotoulene (4-NT), 2,4-Dinitrotoulene (2,4-DNT), 1,3-Dinitrobenzene (1,3-DNB), 2,6- Dinitrotoulene (2,6-DNT) has been done by exploring the photoluminescent behaviour of chemically stable Cu3(BTC)2. Synthesized MOF is extremely sensitive towards 4-NA, which is having PL quenching efficiency of 82.61% with highest quenching rate till reported. Indeed, a large quenching coefficient KSV = 34.02 × 10-7 M-1 and correlation coefficient R2 = 0.9962 in KSV plot have been elucidated with limit of detection (LOD) = 0.7544 ppb. The possible ways of luminescence quenching are successfully explained by the combination of Photoinduced Electron Transfer (PET) and Resonance Energy Transfer (RET) mechanisms. Additionally, the Density Functional Theory (DFT) calculations have been employed to support the experimental results. Cu3(BTC)2 fully demonstrates the power of a multi component MOF, which provides a feasible pathway for the design of novel material towards fast responding luminescence sensing and photocatalytic degradation of pollutants.

Direct Rapid Determination of Trace Aluminum in Various Water Samples with Quercetin by Reverse Phase High-Performance Liquid Chromatography Based on Fabric Phase Sorptive Extraction Technique.

The determination of trace levels of aluminum by high-performance liquid chromatography (HPLC) with UV detection using quercetin, a natural bioactive flavonol, as a metal complexation agent is presented in the current article. The developed method has been successfully applied to the direct determination of aluminum in water samples collected from various sources. A preconcentration technique is indispensable due to the presence of aluminum in environmental water at trace levels. Fabric phase sorptive extraction (FPSE), a relatively new but promising sample preparation technique, was applied to preconcentrate quercetin-Al(III) complex from water samples. Efficient extraction of the quercetin-Al(III) complex from aqueous samples has been accomplished by applying FPSE using a cellulose fabric substrate coated with sol-gel C18 hybrid nanocomposite sorbent. Baseline separation of Al-quercetin complex has been achieved on a reverse phase C18 column with the use of acetonitrile: 3% acetic acid (30:70; v/v) as the mobile phase at a flow rate of 1.0 mL/min. The new FPSE-HPLC-UV method can be used for the routine screening of Al ions in various water samples with high sensitivity, precision and reliability.

A Review on Recent Applications of High-Performance Liquid Chromatography in Metal Determination and Speciation Analysis.

High-performance liquid chromatography (HPLC) has several advantages over the conventional methods due to their operational simplicity. It is a vital tool to determine metal ions having same mass but different electronic configuration, to separate complex mixtures and to resolve ions that may be indistinguishable by mass spectrometry alone. Metal ions play vital role in many biological processes and involved in setting up of many diseases. Therefore, the development of simple methods for the detection and quantification of metals in real samples might serve as diagnostic tools for various diseases. This review article focuses on the recent main feature of this technique, i.e. speciation of metal ions and their applications to series of problem of metal ion chemistry in different environmental matrixes. Speciation of metals is of increasing interest and has a great importance because of bioavailability, environmental mobility, toxicity and potential risk of metals. With the capability of partitioning the complex species of different metal ions, HPLC is an efficient technique for this task. This review summarizes recent advances in the development of HPLC to the fundamental understanding of metal ion chemistry in the environment and discusses all the issues that still need a lot of consideration. It has been classified into different sections depending on the role of HPLC in separation used and metal speciation; furthermore, the underlying sample preconcentration techniques and detection systems involved for the determination of metal ions and their applications were discussed.