Search

Surface folded composites were prepared in situ using CoNi LDH hybrid films loaded with nitrogen-doped carbon dots on self-assembled ZnO microspheres (ZnO@CoNi LDH-NCDs). It acts as an electrode which has excellent sensing performance for hydrazine.

An ultraviolet light emitting diode (UV-LED) array chip as the irradiation source for nano-TiO2 catalyzed photochemical vapor generation (PCVG) was combined with a hollow electrode point discharge microplasma optical emission spectrometer (HEPD-OES) to realize instrumental miniaturization, and utilized for quantitative analysis of trace selenium (Se). Under the irradiation of the UV-LED array chip, Se(IV) and Se(VI) could be effectively converted into volatile species in a miniature quartz coil coating with nano-TiO2 on its inner wall as a photocatalyst. Meanwhile, volatile analyte species were totally guided into the hollow electrode and transported into the inside of micro-discharge plasma for excitation and enhanced sensitivity. Experimental conditions of PCVG and HEPD-OES were investigated in detail using an analytical line of Se at 203.98 nm through the peak area integrated for quantitation. Under optimized experimental conditions of 0.6 mL sample volume, 10% (v/v) acetic acid, 370 nm and 50 W LED, and 75 s UV irradiation, Se(IV) and Se(VI) could be detected with the same LODs, 3.9 μg L−1 and 4.1 μg L−1, respectively. The accuracy of the proposed method was validated by the analysis of the Certified Reference Materials (CRMs, GBW(E)080395 and BWB2427-2016) and real water samples. With the advantages of high compatibility, high efficiency, small size and low power consumption, the integration of UV-LED array chip based PCVG and HEPD-OES would be beneficial to fabricate miniaturized and portable devices for field analysis.

A method of cobalt ion assisted enhancement of photochemical vapor generation-atomic fluorescence spectrometry (PVG-AFS) was proposed for sensitive determination of ultratrace tellurium(IV). With a mixture of 5% (v/v) formic acid and 20% (v/v) acetic acid as the reaction medium, more than 13-fold improvement in AFS intensity for Te(IV) was achieved simply by adding 1 mg L−1 Co2+ as a homogeneous catalyst. A possible reaction mechanism was proposed with the characterization results of GC-MS and electron paramagnetic resonance (EPR). Under optimal conditions, the limit of detection (LOD) for Te(IV) was 0.06 μg L−1, with a relative standard deviation (RSD) of 1.3% (10 μg L−1 Te, 7 times). The accuracy and utility of this methodology were validated by analysis of real water samples, with satisfactory recoveries of 91–108%.

In this work, a 3D ultra-thin NiCo-LDH nanosheet array coated Cu nanoparticles on carbon cloth (NiCo-LDH@Cu NSA/CC) was ultrafast synthesized by plasma magnetron sputtering for the first time. This method has low toxicity and is easy to operate. As a durable and efficient 3D heteronanoarray electrocatalyst for glucose detection, NiCo-LDH@Cu NSA/CC has higher stable conductivity and faster electron transport rate than NiCo-LDH NSA/CC and Cu nanoparticles, which work through synergistic effect to form a high-performance sensing platform. The NiCo-LDH@Cu NSA/CC heteronanosheet structure has good electrocatalytic performance for glucose oxidation, with the sensitivity of the two linear ranges (0.001-1 mmol L

Composited carbon nanomaterials have attracted wide attention and are used for high-sensitivity biological assays due to their low toxicity, good biocompatibility, and excellent electrical conductivity. To further promote electron transfer and enhance electrocatalytic activity to detect dopamine (DA), this study proposed carbon dots (CDs) based on glycerol synthesized by liquid dielectric barrier discharge (DBD) microplasma. Combined with the multi-walled carbon nanotubes (MWCNTs) with excellent electrical conductivity, a composited carbon nanomaterial electrode of CDs/MWCNTs was constructed. As a DA biosensor, the interaction and electron exchange between MWCNTs, CDs, and DA can be enhanced thanks to the π-π stacking force, thereby facilitating the sensitive electrochemical detection of DA. The sensor exhibits good sensing performance toward DA detection with a linear range of 2.0-100 μM, a limit of detection (LOD) of 11.08 nM (S/N = 3), and a sensitivity of 29020 μA cm

A miniaturized/portable visual colorimetric system based on hydride generation headspace solid phase extraction (HG-HS-SPE) was proposed for arsenic detection by naked eyes. As(III) was transformed into AsH

Chemical vapor generation (CVG) is widely used in analytical atomic spectrometry, with advantages of high efficiency of sample introduction (vapor generation and transportation) and matrix separation. Photochemical vapor generation (Photo-CVG) is a new subset of CVG and it has been demonstrated a powerful alternative to conventional CVG techniques due to its inherent advantages. For a long time, most research works have been devoted to improving vapor generation efficiency and expanding the vaporable element scope of Photo-CVG. Nowadays, with the help of nanomaterials and enhancement reagents, Photo-CVG covers a wide range of detectable elements and the vapor generation efficiency of some elements has been improved significantly. In this review, we summarizes the developments and applications of nanomaterials/enhancement reagents assisted Photo-CVG for analytical atomic spectrometry, including TiO2 and TiO2-based composites, MOFs and some metal ions utilized as photocatalysts, photo-oxidation/reduction and enhancement reagents; as well as nanomaterials for preconcentration/separation in Photo-CVG systems.

The development of an efficient and convenient non-enzymatic glucose (Glu) sensor is an extremely attractive and challenging subject. In this work, a 3D cobalt phosphide coated nickel-cobalt layered double hydroxide heteronanosheet array on Ni foam (CoxP@NiCo-LDH NSA/NF) was constructed using electrodeposition and high-temperature phosphating technology. Its unique heteronanosheet array structure and synergistic effect resulting in excellent electrochemical activity for Glu. The response time of the sensor is ultra-fast (

Selenium was taken as an example to investigate the effect of variable ultraviolet (UV) wavelength and intensity on its photochemical vapor generation (photo-CVG) process. A broadband laser-driven light source (LDLS) and a UV lamp were utilized as irradiation sources for the photo-CVG of trace selenium which was sensitively detected by atomic fluorescence spectrometry (AFS). Five filters with bandpass at different wavelength (254 nm, 285 nm, 315 nm, 365 nm and 395 nm) were used to filtrate the light from the LDLS and the UV lamp. The signal change of Se(VI) by photo-CVG-AFS was monitored when a TiO2-coated quartz coil was irradiated by variable wavelength and intensity. The experimental results indicated: (1) the efficiency of Se(VI) photo-CVG varied with irradiation wavelength; (2) a synergistic effect existed for the photo-CVG, and the efficiency of the full spectrum was thus better or close to the sum of all wavelengths; and (3) the efficiency of Se(VI) photo-CVG was also affected by the UV intensity.

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.

Nano g-C 3 N 4 /TiO 2 composite was synthetized and utilized as a novel photocatalyst for enhanced photochemical vapor generation for sample introduction to atomic fluorescence spectrometry. High reduction efficiency for Se (VI) was obtained to facilitate its ultrasensitive determination by atomic fluorescence spectrometry, with a limit of detection of 0.08 ng mL − 1 . The photocatalytic mechanism of this composite was also discussed and demonstrated its highly efficient photocatalytic capacity and promissing applications in trace selenium (VI) determination and extraction.

Inductively coupled plasma (ICP) is one of the most popular sources in analytical atomic spectrometers, including inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). There are several unique independent advantages for either of them. Therefore, a simultaneous elemental analysis system was established for synergetic work of ICP-MS and ICP-OES by sharing one ICP to improve the analytical figures of merit. To demonstrate its unique utility, several special applications were studied, including correction of interferences for each other, synergetic determination for accurate analysis and combinatorial analysis for larger linear ranges of calibration curves.

Flame synthesis is one of the important methods for the synthesis of nanomaterials. In this work, NiO nanoparticles on carbon cloth (NiO/CC) were synthesized via a flame method, and the synthesized NiO/CC was used as a non-enzymatic sensor for the detection of glucose and formaldehyde. NiO/CC shows an excellent analytical performance for glucose sensing with a satisfactory reproducibility and selectivity, providing a response time as short as 3 s, a wide detection ranging from 5 μM to 2 mM, a LOD with 7.45 nM (S/N = 3), and a sensitive response with 4025 μA mM−1cm−2. Furthermore, the sensor also has a sensitive response to formaldehyde, a LOD of 6.8 nM (S/N = 3), a sensitivity of 5752 μA mM−1cm−2 and a response time of 3 s were obtained.

In this work, magnetic Fe3O4@ZIF-8 core-shell nanoparticles (MNPs) were employed for effective adsorption of inorganic arsenic for preconcentration, with adsorption mechanism thoroughly discussed. The adsorbed inorganic arsenic was easily separated by a magnet along with the MNPs from the sample matrix, with possible matrix interference eliminated. The MNPs were then completely dissolved in hydrochloric acid prior to the determination of inorganic arsenic by hydride generation-atomic fluorescence spectrometry. The Fe3O4@ZIF-8 MNPs were prepared with a facile step-by-step assembly method in aqueous solution at room temperature. Under the optimized conditions, the sensitivity for inorganic arsenic determination was significantly increased through preconcentration, with satisfactory analytical merits obtained.

The NiCl(OH) nanosheet array grown in situ on the carbon cloth (NiCl(OH) NS/CC) was synthesized using only anhydrous ethanol and NiCl2·6H2O as a raw material in a mild hydrothermal method. In this paper, NiCl(OH) NS/CC was used as the working electrode for electrochemically sensing glucose under alkaline conditions. Compared with some reports of nickel-based electrochemical detection of glucose, the NiCl(OH) NS/CC electrochemical sensor demonstrates a high sensitivity of 8052.0 μA mM−1 cm−2, a wide linear range of 0.001–3.45 mM, a lower detection limit of 0.29 μM and a response time of less than 5 s. In addition, our sensors can effectively detect glucose in serum and saliva of human beings. Furthermore, the NiCl(OH) NS/CC catalyst has good long-term stability and is highly selective for glucose detection.

Selenium was the first reported element that could be converted into its volatile compounds via photochemical vapor generation (photo-CVG) process before its atomic spectrometric detection. Photo-CVG is a newly emerging vapor generation technique, offering its inherent advantages of matrix interferences eliminated and high vapor efficiency etc., photo-CVG has been combined with various methods for selenium determination and mechanism exploration. Herein, we summarize the development of selenium in photo-CVG from the first report in 2003, the mechanisms of selenium with or without TiO2 were discussed and its applications for selenium determination, speciation analysis and prereduction were summarized.

Atomic fluorescence spectrometry (AFS), as one of the common atomic spectrometric techniques with high sensitivity, simple instrumentation, and low acquisition and running cost, has been widely used in various fields for trace elemental analysis, notably the determination of hydride-forming elements by hydride generation atomic fluorescence spectrometry (HG-AFS). In recent years, the soaring demand of field analysis has significantly promoted the miniaturization of analytical atomic spectrometers or at least instrumental components. Various techniques have also been developed to approach the goal of portable/miniaturized AFS instrumentation for field analysis. In this review, potentially portable/miniaturized AFS techniques, primarily involving advanced instrumental components and whole instrumentation with references since 2000, are summarized and discussed. The discussion mainly includes five aspects: radiation source, atomizer, detector, sample introduction, and miniaturized atomic fluorescence spectrometer/system.