Fujian Xu

Metal–organic framework MIL-53(Fe) for highly selective and ultrasensitive direct sensing of MeHg+

A simple and rapid fluorescence sensing platform based on the MIL-53(Fe) MOF was developed for fast, highly selective and ultrasensitive direct determination of MeHg(+).

Metal-organic frameworks of zeolitic imidazolate framework-7 and zeolitic imidazolate framework-60 for fast mercury and methylmercury speciation analysis

A fluorescence sensing platform based on metal-organic frameworks (MOFs) nanoparticles (NPs) of both zeolitic imidazolate framework-7 (ZIF-7) and zeolitic imidazolate framework-60 (ZIF-60) was developed for speciation analysis of inorganic Hg [Hg(II)] and methylmercury (MeHg(+)). Microwave-ultrasound assisted synthesis was employed for the preparation of ZIF-7 and ZIF-60 NPs, with short reaction time, easy procedure, and small particle size obtained. Based on strict cavity confinement of the ZIF-7 and ZIF-60 structures, the proposed method exhibited excellent selectivity for both Hg(II) and MeHg(+), even in the presence of the other Hg species or various cations or anions with the concentration of 50 times high. Effect of pH and ionic strength on sensing behaviour of the ZIF MOF was studied as well. The calculated detection limit is 3 ng mL(-1) and 6 ng mL(-1) for Hg(II) and MeHg(+), respectively. Furthermore, the application of the developed method to the analysis of local drinking water was demonstrated to be feasible, and the obtained recovery was 102% and 96.2% for Hg(II) and MeHg(+), respectively.

Nanomaterials in speciation analysis of mercury, arsenic, selenium, and chromium by analytical atomic/molecular spectrometry

ABSTRACT The toxicity of elements largely depends on their chemical forms. Therefore, the elemental speciation analysis is of great importance and a hot topic in environmental science and engineering, food science, and biology. The use of nanomaterials in spectrometric detection provides a convenient, versatile, and sensitive technique for elemental speciation analysis. In this concise review, we aim to provide a brief overview of the versatility of nanomaterials in spectrometric elemental speciation analysis with focus on four elements: mercury, arsenic, chromium, and selenium. Various types of nanomaterials, together with their roles in the speciation analysis developed with prevailing spectrometric techniques, are discussed. We also offer an insight into the research trend of the application of nanomaterials for chemical speciation analysis.

Two-dimensional MoS2 nanosheets as a capillary GC stationary phase for highly effective molecular screening

Stable layered MoS2 nanosheets were employed as a stationary phase in gas chromatography. A wide range of different analytes were screened with excellent separation efficiency.

A novel capillary microplasma analytical system: interface-free coupling of glow discharge optical emission spectrometry to capillary electrophoresis

It was found that a capillary electrophoresis (CE) process can be induced by starting a low-temperature d.c. liquid-electrode glow discharge (GD). A novel capillary microplasma analytical system (C-μPAS) was constructed by interface-free coupling of d.c. glow discharge optical emission spectrometry (GD-OES) to CE and was applied in elemental (speciation) analysis. A GD was generated at one end of a capillary, and initiated not only a capillary electrophoresis process but also a microplasma; a sample was injected at the other end of the capillary, separated by CE, and detected by GD-OES. This portable C-μPAS integrates introduction of the sample, separation of the analyte species, and detection of the analytical signal into one unit. The performance of this new analytical system was first evaluated by the analysis of a mixed aqueous solution of mercury, cadmium, chromium, sodium and organic or inorganic species without derivatization, and the absolute limits of detection (LODs) were found to be in the range of 0.5 to 500 picograms under the optimized experimental conditions. Preliminary experimental results for mercury speciation showed that it provided effective separation and results as accurate as those obtained by HPLC-ICP-MS. The working mechanism of this system is discussed, with the theoretically calculated electron temperature and electron density of the microplasma. This C-μPAS has the advantages of portable instrumentation, green chemistry (low power consumption, tiny sampling volume and almost no pollutants), high sensitivity (detection of optical emissions), low interference (separation by CE and spectral resolution), versatility (organic, inorganic, cationic or anionic analytes), and fast analysis (several minutes). It should have a very promising future in a range of areas such as environmental analysis, metallomics research, water analysis, online monitoring and field analytical chemistry.

A miniaturized UV-LED photochemical vapor generator for atomic fluorescence spectrometric determination of trace selenium

A miniaturized UV-LED photochemical reactor is proposed for selenium photochemical vapor generation (Photo-CVG). The miniaturized Photo-CVG reactor with a coin size mainly consists of an ultraviolet light-emitting-diode (UV-LED) and a quartz coil with nano-TiO2 coating on its inner wall. It was coupled with an atomic fluorescence spectrometer (AFS) as a sample introduction device for trace selenium determination. The nano-TiO2 coating process, UV-LED wavelength and correlative experimental parameters as well as potential interference were investigated in detail. Under optimized experimental conditions, limits of detection of 0.21 and 0.28 μg L−1 for Se(VI) and Se(IV) were obtained, respectively, with a relative standard deviation (n = 3) of 2.5% and 1.0% at 20 μg L−1. The potential application of this UV-LED Photo-CVG AFS was demonstrated by successfully analyzing a certified reference water sample and several mineral water samples.