Ultrasound assisted dispersive solid phase microextraction of inorganic arsenic from food and water samples using CdS nanoflowers combined with ICP-OES determination

Simultaneous extraction of five heavy metal ions from root vegetables via dual-frequency ultrasound-assisted enzymatic digestion

The dual-frequency ultrasound-assisted enzymatic digestion (DUED) technique was developed for synchronous green extraction of five heavy metal ions in root vegetables. The combination of α-amylase, cellulase, and papain showed significant advantageous in extracting heavy metal ions. Under optimized dual-frequency ultrasonic conditions, the extraction rates of Cr, As, Cd, Pb, and Hg in carrots reached 99.04%, 105.88%, 104.65%, 104.10%, and 103.13% respectively. And the extraction process is highly efficient, completing in just 15 min. Compared to conventional microwave-assisted acid hydrolysis method, this technique eliminates the need for high-temperature concentrated acid, enhancing its environmental sustainability while maintaining mild reaction conditions, making it ideal for biosensors application. Additionally, simultaneous extraction and detection of four heavy metals in lotus roots were successfully achieved by using DUED and a fluorescent paper-based microfluidic chip. The obtained results are consistent with those obtained using conventional methods.

Environmentally friendly nanoflower Al2O3@carbon spheres as adsorbent for dispersive solid-phase microextraction of copper and lead in food and water samples

A fast and simple dispersive solid-phase microextraction method (d-SPμE) was described for the determination of copper and lead in food, water, and sediments using FAAS. Firstly, nanoflower Al2O3@carbon spheres composite (NF Al2O3@CSs) was synthesized and then characterized. The obtained NF Al2O3@CSs was used for the d-SPμE of copper and lead in aqueous solutions. The influence of important parameters like pH, contact time, eluent conditions, volume of sample, and competing ion effects on the d-SPμE efficiency of copper and lead was investigated. They were pH, 7; eluent, 2 mol L-1 HCl (2 mL); sample volume, 250 mL for copper and 150 mL for lead with recoveries ≥90%. The adsorption and elution of analytes on NF Al2O3@CSs were realized quickly without vortexing. The LODs of the d-SPμE for copper and lead were found to be 0.69 μg L-1 and 2.8 μg L-1, respectively, while its PF was 125 for copper and 75 for lead. The intra-day precision and inter-day repeatability (RSD%, n = 7) were 1.3% and 1.6% for Cu(II) and 2.3% and 3.2% for Pb(II), respectively. Finally, the accuracy of the d-SPμE was investigated by determination of the analytes in four certified reference materials (TMDA-53.3 Lake water, NW-TMDA-54.6 Lake water, NIST 1573a Tomato leaves, and NIST RM 8704 Buffalo River Sediment). The analyte recoveries together with analyses of dam water, river water, wastewater, sea water, sumac, tea, chocolate, and lentils were studied. The results indicate that recoveries ranged from 90 to 103% in water samples and 91 to 110% in food samples.

Arsenic speciation by using emerging sample preparation techniques: a review

Arsenic is a hazardous element that causes environmental pollution. Due to its toxicological effects, it is crucial to quantify and minimize the hazardous impact on the ecology. Despite the significant advances in analytical techniques, sample preparation is still crucial for determining target analytes in complex matrices. Several factors affect the direct analysis, such as trace-level analysis, advanced regulatory requirements, complexity of sample matrices, and incompatible with analytical instrumentation. Along with the development in the sample preparation process, microextraction methods play an essential role in the sample preparation process. Microextraction techniques (METs) are the newest green approach that replaces traditional sample preparation and preconcentration methods. METs have minimized the limitation of conventional sample preparation methods while keeping all their benefits. METs improve extraction efficacy, are fast, automated, use less amount of solvents, and are suitable for the environment. Microextraction techniques with less solvent consumption, such as solid phase microextraction (SPME) solvent-free methods, and liquid phase microextraction (LPME), are widely used in modern analytical procedures. SPME development focuses on synthesizing new sorbents and applying online sample preparation, whereas LPME research investigates the utilization of new solvents.

Novel covalent organic frameworks based electrospun composite nanofiber membranes as pipette-tip strong anion exchange sorbent for determination of inorganic arsenic in rice

Novel covalent organic frameworks (COFs) based PAN@TpBD(NH₂)₂ electrospun composite nanofiber membranes (ECNMs) were fabricated as strong anion exchange sorbent by implementing electrospinning technology. The finished sorbent was characterized, and key parameters of pipette-tip solid phase extraction (PTSPE) procedures were investigated. Inorganic arsenic (iAs) was successfully separated from rice under the optimal precondition conditions, and quantified by hydride generation-atomic fluorescence spectrometry (HG-AFS). This PTSPE-HG-AFS methodology achieved 0.015 μg L^-1 detection limit, 4.67 % relative standard deviation, and 86.48～99.11 % recoveries. In this work, preparation and characterization of this novel COFs-based anion exchange sorbent, PAN@TpBD(NH₂)₂ ECNMs, is described and its suitability for PTSPE applications is demonstrated.

Determination and speciation of trace inorganic arsenic species in water samples by using metal organic framework mixed-matrix membrane and EDXRF spectrometry

A facile method to selectively determine trace As(V) species in the existence of As(III) one in water samples was developed, which was based on the batch adsorption process by using a miniaturized MIL-101(Fe) mixed-matrix membrane (MOF-MMM) followed by a direct determination through energy dispersive X-ray fluorescence (EDXRF) spectrometry. The quantitative adsorption of As(V) was achieved at pH (3-6) from 30 mL sample in 120 min of equilibrium time by employing the membrane with a monolayer adsorption capacity of Q_o = 1.953 mg g^-1. The direct determination of As(V) adsorbed on the membrane by EDXRF spectroscopy provided a method, not only easy-to-use and operable without elution stage, but also cost effective due to low gas consumption during the analysis. With a limit of detection of 0.094 μg L^-1, analytical performance of the method, which was evaluated on fortified real water samples with three levels of As(V) (5, 10 and 50 μg L^-1), demonstrated good recoveries in the range of 98(±3)-105(±10)%. Furthermore, the speciation of As(III) and As(V) in the fortified real samples containing other ionic species was also successfully achieved by described approach with characteristics of simple, cheap, viable and reproducible.

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.

Simultaneously speciation and determination of manganese (II) and (VII) ions in water, food, and vegetable samples based on immobilization of N-acetylcysteine on multi-walled carbon nanotubes

A novel method based on the immobilization of N-acetylcysteine on chloro-functionalized multi-walled carbon nanotubes (MWCNTs@NAC) was used for the speciation of manganese ions [Mn (II) and Mn(VII)] in water samples. Also, the total manganese (TMn) in vegetables and food samples was determined by the AT-FAAS. By ultrasound-assisted-dispersive ionic liquid trap micro solid-phase extraction (UA-DILT-μ-SPE), the Mn (II)/Mn(VII) ions were extracted in the presence of MWCNTs@NAC for 50 mL of water samples at a pH of 6.5 and 3.0, respectively. The adsorption capacity of MWCNTs@NAC for Mn(II) and Mn(VII) ions was obtained at 146.7 mg g^-1 and 138.8 mg g^-1, respectively. Under the optimized conditions, the detection limits (LOD), linear range (LR), and enrichment factor (EF) for Mn(II) and Mn(VII) ions were obtained (0.12 μg L^-1; 0.14 μg L^-1), (0.48-36 μg L^-1; 0.55-38.1 μg L^-1) and (100.2; 94.5), respectively. The proposed methodology was successfully validated by the CRM samples.

Hydrolytic enzyme modified magnetic nanoparticles: An innovative and green microextraction system for inorganic species in food samples

In the presented study, the usability of hydrolytic enzyme immobilized magnetic nanoparticles as an extraction agent for the microextraction of metal ions from food samples was investigated. α-amylase modified magnetic carbon nanotubes (α-amylase-Fe₃O₄/MWCNTs) was used as an extraction agent for direct microextraction of trace arsenic from food sample phase into liquid phase medium prior to its ICP-MS determination. In extraction studies using hydrolytic enzymes, it is impossible to recover the free soluble enzyme after extraction without losing its activity. In our study, this problem was overcome by immobilizing the hydrolytic enzyme on magnetic support. In this way, α-amylase-Fe₃O₄/MWCNTs as an extraction agent with a reuse property of at least six times was used. α-amylase-Fe₃O₄/MWCNTs was characterized by FT-IR, XRD, SEM, SEM-EDX, VSM, TGA, and DTG techniques. Optimization of the presented method was performed using 1568 A rice flour certified reference material. Analytical parameters such as type of hydrolytic enzyme, pH and volume of the aqueous phase, extraction temperature and ultrasonic irridation time were optimized. The microextraction step was performed in ultrasonic water bath within only ∼15 min. Limit of detection (LOD), limit of quantification (LOQ) and relative standard deviation (RSD %) values for the developed method were found to be 14.3 μg kg^-1, 47.3 μg kg^-1 and 7.5%, respectively. The method was successfully applied to the analysis of arsenic contents of different rice and flour samples.

Platinum nanoparticles-embedded raspberry-liked SiO2 for the simultaneous electrochemical determination of eugenol and methyleugenol

Based on platinum nanoparticle-embedded raspberry-liked SiO₂, a sensitive and selective electrochemical sensor was developed for simultaneous determination of eugenol (EU) and methyleugenol (MEU). Raspberry-liked SiO₂ (RL-SiO₂) was characterized with open pores on the surface, which can be used as a path for utilizing the inner space fully. So, platinum nanoparticles (Pt NPs) could be embedded in the inner and outer surface of RL-SiO₂. As a carrier, RL-SiO₂ not only avoided the agglomeration of the Pt NPs but also improved the catalytic performance. Therefore, the prepared Pt NPs@RL-SiO₂/GCE exhibited excellent electrocatalytic activity for simultaneous determination of EU and MEU; the linearity ranges were 0.50 ~ 60 μmol/L for EU at a working potential of 0.65 V (vs. saturated calomel electrode) and 0.50 ~ 50 μmol/L for MEU at a working potential of 1.10 V; the detection limits were 0.12 μmol/L and 0.16 μmol/L (S/N=3); and the relative standard deviations (RSDs) were 3.2% and 4.5%, respectively. In addition, Pt NPs@RL-SiO₂/GCE was successfully applied to the analysis of fish samples; the obtained recoveries were between 92.0 and 107%. Notably, the results conducted on samples were highly consistent with those obtained from high-performance liquid chromatography. It can be concluded that the study provided a simple method for simultaneous electrochemical determination of EU and MEU in fish samples. Schematic illustration of the preparation of RL-SiO2@Pt NPs/GCE for simultaneous determination of eugenol and methyleugenol in fish samples.