Determination of Cobalt in Food and Water Samples by Ultrasound-assisted Surfactant-enhanced Emulsification Microextraction and Graphite Furnace Atomic Absorption Spectrometry

Evaluation of green silicone surfactant-based vortex assisted dispersive liquid-liquid microextraction for sample preparation of organophosphorus pesticide residues in honey and fruit sample

A vortex assisted surfactant enhanced emulsification liquid-liquid microextraction based on non-ionic silicone surfactant was successfully developed for the determination of organophosphorus pesticides in food samples coupled to gas chromatography-mass spectrometry. A new type of non-ionic silicone surfactant composed of polysiloxane chains was employed as a green emulsifier to facilitate the emulsification of extraction solvent into the sample matrix, thereby intensifying the mass transfer of target analytes into the organic phase. The variables that affect the extraction were systematically optimized: 80 μL of hexane and 0.5% (v/v) of silicone surfactant were used as extraction solvent and surfactant respectively, the solution was mixed well under vortex agitation for 1 min with the addition of 4% (w/v) sodium sulfate. Under optimum conditions, the linearity of the method was obtained in the range of 0.1 - 200 μg/kg with good coefficient of determination varying from 0.9986 to 0.9996. The LOD and LOQ were in between 0.008 - 0.1 μg/kg and 0.02 - 0.3 μg/kg, respectively. Application of the proposed method to real samples gave satisfactory recovery values (80 - 118%) for the target analytes. The suggested approach has also proven to be convenient, expeditious and environmentally benign. This article is protected by copyright. All rights reserved.

Facile and High-yield Synthesis of N-doped Carbon Quantum Dots from Biomass Quinoa Saponin for the Detection of Co2

Hydrothermal synthesis of carbon quantum dots (CQDs) from natural biomass is a green and sustainable route for CQDs applications in various fields. In this work, the preparation and characterization of CQDs based on quinoa saponin were investigated. The optimum synthetic conditions determined by orthogonal experiments were as follows: 2 g quinoa saponin powder and 0.04 mol ethylenediamine reacted at 200°C for 10 h. The relative fluorescence quantum yield (QY = 22.2%) can be obtained, which is higher than some results reported in the literatures. The prepared CQDs had a small and uniform size (∼2.25 nm) and exhibited excitation wavelength-dependent blue light emission behavior. The CQDs displayed excellent sensitivity for Co²⁺ detection along with good linear correlation ranging from 20 to 150 µM and the detection limit of 0.49 µM. The CQDs prepared in this experiment were successfully implanted into soybean sprouts for fluorescence imaging. The sprouts could grow healthily even soaked in the CQDs solution for two weeks, demonstrating the low toxicity of the CQDs. The advantages of the CQDs, such as low cost, ease of manufacture, nontoxicity, and stability, have potential applications in many areas such as metal ion detection and biosensing.

One step hydrothermal synthesis and characterization of moss like MWCNT-Bi2S3 nanomaterial for solid phase extraction of copper

The present work was designed with the aim to one step simple hydrothermal synthesis of moss like MWCNT-Bi2S3 nanomaterial as solid phase extraction sorbent for separation, preconcentration and determination of copper in tobacco and food samples. Cu(II) ions was strongly retained on the MWCNT-Bi2S3 nanomaterial at the pH 7.0 and was successfully desorbed by using 1.5mL of 4M HNO3. The copper concentration in eluent was determined by flame atomic absorption spectrometer. The certified reference material (NC SZC 73033 Scallion) was analyzed for the verification and accuracy of the proposed method. This work was interpreted statistically and found the analytical performance of the proposed method which consist of preconcentration factor (20), limit of quantification (13.1µgL-1) and relative standard deviation (2.2%), respectively. It was concluded that this method was applied for the detection of copper from different types of tobacco and food samples successfully.

Synthesis and characterization of a novel chloromethylated polystyrene-g-2-adenine chelating resin and its application to preconcentrate and detect the concentration of mercury ions in edible mushroom samples

Edible mushrooms are widely usedtoday but the heavy metal pollution of edible mushrooms is not conducive to its industrialization. A novel chloromethylated polystyrene-g-2-adenine chelating resin (AR resin) with simple technology, high adsorption capacity, significant selectivity, and good regenerability was synthesized. Combined with the UV-Vis method, it was applied to mercury preconcentration and determination. The results indicated that the AR resin is essentially free from interferences, which can contribute to accurate determination in waters and foods. Optimization of the resin synthesis was carried out by using response surface methodology. The adsorption properties of the resin for Hg(II) were investigated by batch and column experiments. The statically and dynamic saturated adsorption capacities were 383.4 and 417.0 mg/g. The adsorption kinetic and equilibrium data were well fitted to the second-order model and the Langmuir isotherm model, respectively. Furthermore, the resin and its metal complexes were studied by Fourier transform infrared spectroscopy and thermogravimetric analysis.