Development of dispersive liquid-liquid microextraction based on solidification of floating organic drop for the determination of trace nickel

Ultra-Sensitive Determination of Cadmium in Food and Water by Flame-AAS after a New Polyvinyl Benzyl Xanthate as an Adsorbent Based Vortex Assisted Dispersive Solid-Phase Microextraction: Multivariate Optimization

Background: Cadmium (Cd) is a very toxic and carcinogenic heavy metal even at low levels and it is naturally present in water as well as in food. Methods: A new polyvinyl benzyl xanthate (PvbXa) was synthesized and used as a new adsorbent in this work. It contains pendant sulfide groups on the main polystyryl chain. Using this new adsorbent, PvbXa, a vortex-assisted dispersive solid-phase microextraction (VA-dSPµE) procedure was developed for the determination of cadmium from food and water samples via flame atomic absorption spectrophotometry (FAAS). Synthesized PvbXa was characterized by 1H Nuclear magnetic resonance (NMR) Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The different parameters of pH, sample volume, mixing type and time, sorbent amount, and eluent time were optimized using standard analytical methods. Results: The optimized method for assessment of Cd in food and water samples shows good reliability. The optimum conditions were found to be a 0.20-150 µg L-1 linear range, 0.06 µg L-1 LOD, 0.20 µg L-1 LOQ, 4.3 RSD %, and a preconcentration factor of 160. Conclusions: The statistically experimental variables were utilized using a central composite design (CCD). The present method is a low-cost, simple, sensitive, and very effective tool for the recovery of Cd.

A New Trend and Future Perspectives of the Miniaturization of Conventional Extraction Methods for Elemental Analysis in Different Real Samples: A Review

Sample preparation is one of the viable procedures to be used before analysis to enhance sensitivity and reduce the matrix effect. The current review is mainly emphasized the latest outcome and applications of microextraction techniques based on the miniaturization of the classical conventional methods based on liquid-phase and solid-phase extraction for the quantitative elemental analysis in different real samples. The limitation of the conventional sample preparation methods (liquid and solid phase extraction) has been overcome by developing a new way of reducing size as compared with the conventional system through the miniaturization approach. Miniaturization of the sample preparation techniques has received extensive attention due to its extraction at microlevels, speedy, economical, eco-friendly, and high extraction capability. The growing demand for speedy, economically feasible, and environmentally sound analytical approaches is the main intention to upgrade the conventional procedures apply for sample preparation in environmental investigation. A growing trend of research has been perceived to quantify the trace for elemental analysis in different natures of real samples. This review also recapitulates the current futuristic scenarios for the green and economically viable procedure with special overemphasis and concentrates on eco-friendly miniaturized sample-preparation techniques such as liquid-phase microextraction (LPME) and solid-phase microextraction (SPME). This review also emphasizes the latest progress and applications of the LPME and SPME approach and their future perspective.

Trace Determination of Iron in Real Waters and Fruit Juice Samples Using Rapid Method: Optimized Dispersive Liquid-Liquid Microextraction with Synthesized Nontoxic Chelating Agent

The purpose of this research was to optimize a new method for preconcentration and determination of trace iron concentrations in aqueous solutions. For this purpose, a newly synthesized ligand, 3-(3-hydroxy-2-methyl-4-oxopyridin-1(4H)-yl) benzoic acid (3-OH-3-MOPBA), was used in the dispersive liquid-liquid microextraction (DLLME) method coupled with UV-vis spectroscopy. The experiments considering input variables of extractant volume, disperser volume, salt concentration, and pH were designed with the aid of central composite design (CCD). The results were analyzed using response surface methodology (RSM). The limit of detection (LOD) was found to be 4.0 μg L^-1 under the optimized conditions. A calibration curve with a good linearity (R² = 0.9986) was obtained over the concentration range of 15-800 μg L^-1. The relative standard deviations (RSD) were found to be around 2.1% (n = 7). The main advantages of the developed method are simple application, environment friendly, short time, and low cost which makes this method to be applied routinely for measuring iron in various water samples.

Application of Deep Eutectic Solvent Modified Cotton as a Sorbent for Online Solid-Phase Extraction and Determination of Trace Amounts of Copper and Nickel in Water and Biological Samples

Deep eutectic solvent (DES) was used as the extractant to improve the extraction properties of cotton. DES of choline chloride-urea (ChCl-urea) was prepared and immobilized on the surface of cotton fibers. The resulting sorbent was packed on a microcolumn, and a flow injection flame atomic absorption spectrometry was designed for the online separation and determination of trace amounts of copper and nickel. Various parameters affecting the extraction recovery of analytes such as pH, sample volume, sample loading rate, nature, volume, concentration, and flow rate of eluent were investigated and optimized. Under the optimum conditions, the method showed good linearity in the concentration range of 0.25-50.0 and 4.0-125.0 μg L^-1 with the coefficient of determination (r ²) of 0.9991 and 0.9990 for copper and nickel, respectively. The method was very sensitive with the detection limits (defined as 3S_b/m) of 0.05 and 0.60 μg L^-1 for Cu and Ni, respectively. It was successfully applied for the determination of Cu and Ni in water and biological samples. The accuracy of the method was evaluated through the recovery experiments and independent analysis by electrothermal atomic absorption spectrometry.