Application of Ultrasonic Assisted-Dispersive Solid Phase Extraction Based on Ion-Imprinted Polymer Nanoparticles for Preconcentration and Trace Determination of Lead Ions in Food and Water Samples

Dispersive Solid-phase Microextraction of Lead in Waters and Edible Lettuce and Dill Extracts in the Unified Bioaccessibility Method (UBM) Saliva Solution

A new thiosemicarbazide-modified, sulfonamide-based poly (styrene) adsorbent (T-CSPS) was prepared starting from the reaction of chlorosulfonated polystyrene and thiosemicarbazide. It was characterized by SEM-EDX, FT-IR, and zeta potential. The T-CSPS was used as an adsorbent for the first time for the dispersive solid-phase microextraction (d-SPµE) and preconcentration of Pb(II) ions from waters and dill and lettuce extracts in the unified bioaccessibility method (UBM) saliva. Lead was then determined using the FAAS. In the first step of optimization, the solution pH was changed from 2 to 8, and pH 4 with a recovery value of 103% ± 5 was selected. Two milliliters of 2 mol L-1 HCl was chosen as eluent. Contact times were found to be only 2 min. Effects of coexisting ions and sample volume were tested. Under optimal conditions, the preconcentration factor (PF) and the adsorption capacity were 15 and 40 mg g-1. The RSD% was 2.2% and 3.1% for intra-day and inter-day precision, respectively. The LOD and LOQ were found to be 5.1 µg L-1 and 16.9 µg L-1, respectively. The accuracy of the d-SPµE was checked by TMDA-70.2 Lake water and BCR-482 Lichen-certified reference materials and also applying d-SPµE to spiked waters and lettuce and dill extracts in UBM saliva.

Eco-Friendly Simultaneous Estimation of Ponceau 4R and Carmoisine Employing an Analytical Quality by Design-Aided RP-HPLC Method in Commercial Food Samples Utilizing a Green Ultrasound-Assisted Extraction Technique

BACKGROUND

Ponceau 4R (E124) and carmoisine (CMS; E122) are frequently utilized azo synthetic dyes in the food industry owing to their aesthetically pleasing coloration and broad consumer acceptability. It is imperative to prioritize environmentally favorable technologies for quantifying these dyes, as excessive consumption of these poses significant health risks.

OBJECTIVE

The primary objective of this research was to establish a reversed-phase (RP)-HPLC method that could simultaneously detect Ponceau 4R and CMS, implementing green analytical chemistry (GAC) and analytical quality by design (AQbD), using an ultrasound-assisted extraction (UAE) technique in commercial food samples.

METHODS

An Agilent Eclipse Plus column (C18, 250 × 4.6 mm id, 5 µm) was utilized for effective separation with a mobile phase of ethanol-acetate buffer pH 5 (60:40, v/v), flow rate of 1 mL/min, and detection wavelength of 515 nm. Critical variables selected for method optimization were ethanol percentage and flow rate, determined using central composite design (CCD). In order to adhere to the 12 principles of green chemistry, hazardous solvents were substituted with ethanol, which is distinguished by its ease of use, effectiveness, and ecological sustainability. The greenness assessment was conducted utilizing the green analytical procedure index (GAPI), analytical eco-scale (AES), and analytical greenness metrics (AGREE).

RESULTS

The respective retention times for Ponceau 4R and CMS were 2.276 and 3.450 min. The recovery rate of Ponceau 4R and CMS fluctuated between 70% and 102% and 80% and 102%, respectively, across various marketed food samples. The procedure passed validation in accordance with the International Conference on Harmonization Q14 guidelines.

CONCLUSION

The devised method demonstrates that the validation parameters like linearity, precision, sensitivity, and reproducibility are within the specified limits of ICH guidelines. The greenness assesment tools GAPI, AES, and AGREE produced the most favorable results.

HIGHLIGHTS

In future, environmentally sustainable, solvent-based, robust AQbD methodologies for assessing varieties of food colorants may be adopted and improved commercially.

The application progress of magnetic solid-phase extraction for heavy metal analysis in food: a mini review

The emerging sample pretreatment technique of magnetic solid-phase extraction (MSPE) has drawn the attention of researchers owing to its advantages of less reagent consumption, fast separation/enrichment process, high adsorption capacity, and simple operation. This paper presents a review of synthesis techniques, classification, and analysis procedures for MSPE in the detection of heavy metals in food. Magnetic adsorbents derived from silica, metal oxides, carbon, polymers, etc., are applied for the detection of heavy metals in food. Then, the recent development of the technology of MSPE for the analysis of heavy metal extraction in food is summarized in detail. Finally, the future outlook for the improvement of MSPE is also discussed.

Bifunctional Amine- and Thiol-Modified Ti3C2Tx MXene for Trace Detection of Heavy Metals

Surface functionalization of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, also known as MXenes, is a powerful approach for modification of their physical and chemical properties for new applications. In this study, we demonstrate the synthesis of a bifunctional Ti₃C₂T_x MXene modified with amine and thiol groups through a facile condensation reaction. We successfully employed the resulting NH₂/SH-Ti₃C₂T_x MXene as a solid phase in the ultrasonic-assisted dispersive micro solid-phase extraction (d-μ-SPE) method for the analytical determination of heavy metals at trace levels in food and soil samples. The prepared NH₂/SH-Ti₃C₂T_x MXene showed remarkable performance in the ultrasonic-assisted d-μ-SPE method with limits of detection of 0.12 and 2.30 ng mL^-1, with linear dynamic ranges of 0.50-90 μg L^-1 and 10-120 μg L^-1 for cadmium (Cd²⁺) and lead (Pb²⁺) ions, respectively. Furthermore, the extraction efficiencies were greater than 97%, with a relative standard deviation of less than 3% for five separate batch experiments in the determination of 5.0 μg L^-1 of Cd²⁺ and Pb²⁺. This study shows that NH₂/SH-Ti₃C₂T_x can be used as a simple, rapid, reliable, selective, and sensitive material in the d-μ-SPE method for the trace determination of Cd²⁺ and Pb²⁺ in soil and agricultural products. This study demonstrates the utility of MXenes for analytical chemistry and suggests that further advances in methods for the functionalization of MXenes can open new applications for these already exciting materials.

A Novel Electrochemical Sensor Modified with a Computer-Simulative Magnetic Ion-Imprinted Membrane for Identification of Uranyl Ion

In this paper, a novel ion-imprinted electrochemical sensor modified with magnetic nanomaterial Fe₃O₄@SiO₂ was established for the high sensitivity and selectivity determination of UO₂²⁺ in the environment. Density functional theory (DFT) was employed to investigate the interaction between templates and binding ligands to screen out suitable functional binding ligand for the reasonable design of the ion imprinted sensors. The MIIP/MCPE (magnetic ion imprinted membrane/magnetic carbon paste electrode) modified with Fe₃O₄@SiO₂ exhibited a strong response current and high sensitivity toward uranyl ion comparison with the bare carbon paste electrodes. Meanwhile, the MCPE was fabricated simultaneously under the action of strong magnetic adsorption, and the ion imprinted membrane can be adsorbed stably on the electrode surface, handling the problem that the imprinted membrane was easy to fall off during the process of experimental determination and elution. Based on the uranyl ion imprinting network, differential pulse voltammetry (DPV) was adopted for the detection technology to realize the electrochemical reduction of uranyl ions, which improved the selectivity of the sensor. Thereafter, uranyl ions were detected in the linear concentration range of 1.0 × 10⁻⁹ mol L⁻¹ to 2.0 × 10⁻⁷ mol L⁻¹, with the detection and quantification limit of 1.08 × 10⁻⁹ and 3.23 × 10⁻¹⁰ mol L⁻¹, respectively. In addition, the sensor was successfully demonstrated for the determination of uranyl ions in uranium tailings soil samples and water samples with a recovery of 95% to 104%.

Magnetic Ion Imprinted Polymers (MIIPs) for Selective Extraction and Preconcentration of Sb(III) from Environmental Matrices

Antimony(III) is a rare element whose chemical and toxicological properties bear a resemblance to those of arsenic. As a result, the presence of Sb(III) in water might have adverse effects on human health and aquatic life. However, Sb(III) exists at very ultra-trace levels which may be difficult for direct quantification. Therefore, there is a need to develop efficient and reliable selective extraction and preconcentration of Sb(III) in water systems. Herein, a selective extraction and preconcentration of trace Sb(III) from environmental samples was achieved using ultrasound assisted magnetic solid-phase extraction (UA-MSPE) based on magnetic Sb(III) ion imprinted polymer-Fe3O4@SiO2@CNFs nanocomposite as an adsorbent. The amount of antimony in samples was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The UA-MSPE conditions were investigated using fractional factorial design and response surface methodology based on central composite design. The Sb(III)-IIP sorbent displayed excellent selectivity towards Sb(III) as compared to NIIP adsorbent. Under optimised conditions, the enrichment factor, limit of detection (LOD) and limit of quantification (LOQ) of UA-MSPE/ICP-OES for Sb(III) were 71.3, 0.13 µg L-1 and 0.44 µg L-1, respectively. The intra-day and inter-day precision expressed as relative standard deviations (%RSDs, n = 10 and n = 5) were 2.4 and 4.7, respectively. The proposed analytical method was applied in the determination of trace Sb(III) in environmental samples. Furthermore, the accuracy of the method was evaluated using spiked recovery experiments and the percentage recoveries ranged from 95-98.3%.

Determination of lead ions in fish and oyster samples using a nano-adsorbent of functionalized magnetic graphene oxide nanosheets-humic acid and the flame atomic absorption technique

This study aims at the functionalization of magnetic graphene oxide nanosheets and the binding of humic acid as a lead complex ligand. Graphene oxide nanosheets possess a large surface area and various carboxylic acid groups which can be activated easily by activating agents. Therefore, they are suitable to be used for the extraction of heavy metals. To have a better process of extracting lead ions, magnetic graphene oxide was used in this research. Humic acid, as a lead metal complex agent, has an amine functional group which can be bound to modified graphene oxide from one side. The process of constructing the nano-adsorbent proposed for the preconcentration of lead ions as well as its characterization was studied by infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-visible), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The designed nano-adsorbent was tested to measure lead ions in simulated and real samples of sea water, fish, and oysters. The detection limit obtained in the simulated samples was 0.07 μg/L, and the linear range was 0.2-12 μg/L. The apparatus used to measure the ions was a flame atomic absorption device. In the analysis of the real samples, the values obtained through flame atomic absorption were compared with those obtained through furnace atomic absorption. The proposed technique is advantageous due to being cheap, precise, and sensitive for the trace measurement of lead ions.

Multi-functional porous organic polymers for highly-efficient solid-phase extraction of β-agonists and β-blockers in milk

A simple, accurate, and highly sensitive analytical method was developed in this study for the determination of ten β-agonists and five β-blockers in milk. In this method, new adsorbent phosphonic acid-functionalized porous organic polymers were synthesized through a direct knitting method. The synthesis procedure of the materials and the extraction conditions (such as the composition of loading buffer and eluent) were optimized. Benefitting from the high surface area (545–804 m² g⁻¹), multiple functional framework and good porosity, the phosphonic acid-functionalized porous organic polymers showed a high adsorption rate and high adsorption capacity for β-agonists (224 mg g⁻¹ and 171 mg g⁻¹ for clenbuterol and ractopamine, respectively). The analytes were quantified by ultra-high-performance liquid chromatography coupled to high-resolution tandem mass spectrometry. It showed a good linearity (with R² ranging from 0.9950 to 0.9991 in the linear range of 3–5 orders of magnitude), with low limits of quantification ranging from 0.05 to 0.25 ng g⁻¹. The limits of detection of the method for the analytes were measured to be in the range of 0.02 to 0.1 ng g⁻¹. The recoveries of target analytes from real samples on the material were in the range of 62.4–119.4% with relative standard deviations of 0.6–12.1% (n = 4). Moreover, good reproducibility of the method was obtained with the interday RSD being lower than 11.7% (n = 5) and intraday RSD lower than 12.2% (n = 4). The proposed method was accurate, reliable and convenient for the simultaneous analysis of multiple β-agonists and β-blockers. Finally, the method was successfully applied for the analysis of such compounds in milk samples.

Novel phosphonic acid-functionalized porous organic polymers were synthesized through direct knitting method. It shows high adsorption efficiency and high adsorption capacity for multiple β-agonists and β-blockers analysis.

Multi-ion imprinted polymers (MIIPs) for simultaneous extraction and preconcentration of Sb(III), Te(IV), Pb(II) and Cd(II) ions from drinking water sources

Simultaneous extraction and preconcentration of several potentially toxic metal ions have received great attention because of their toxicological effects on aquatic life and human beings. Multi-ion imprinted polymers (MIIP) have proved to be promising adsorbents with excellent specific recognition performance than single-ion imprinted polymer. Therefore, in this study, the MIIP strategy was employed for simultaneous extraction and enrichment of Sb(III), Cd(II), Pb(II) and Te(IV) ions from drinking water sources. MIIPs was used as a sorbent material in ultrasound-assisted dispersive solid phase extraction combined with inductively coupled plasma optical emission spectrometry (UA-DSPE/ICP-OES). The experimental parameters that affect the extraction efficiency and recovery of Sb(III), Cd(II), Pb(II) and Te(IV) were investigated using response surface methodology. Under optimum conditions, the enhancement factors, linear range, limit of detection (LOD) and limit of quantification (LOQ) were 37.7-51.1, 0.04-100 µg L^-1, 0.011-0.28 µg L^-1, 0.037-093 µg L^-1, respectively. The intra-day (n = 10) and inter-day (n = 5) precision expressed as relative standard deviations (%RSDs,) were 3% and 5%, respectively. The proposed UA-DSPE/ICP-OES method was applied for preconcentration and determination of the trace metal ions in environmental samples. Furthermore, the accuracy of the method was evaluated using spiked recovery experiments and the percentage recoveries ranged from 95% to 99.3%.

Determination of Six Tetracyclines in Eggs and Chicken by Dispersive Liquid-Liquid Microextraction Combined with High-Performance Liquid Chromatography

BACKGROUND

The wide livestock usage of tetracyclines may result in drug residues in foods. Therefore, it is necessary to develop reliable methods for the determination of tetracyclines in foods.

OBJECTIVE

A dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography (HPLC) method was developed for the analysis of six tetracyclines in eggs and chicken.

METHODS

After deproteinization, tetracyclines in acidic solutions were concentrated by vortex-assisted DLLME. Followed by the addition of NaCl (35% for eggs and 20% for chicken), a mixture of ionic liquid [Bmim]PF6 and ethyl acetate (300 μL-50 μL for eggs and 200 μL-60 μL for chicken) was used as the extractant. After centrifugation, the extract was collected for HPLC analysis.

RESULTS

The developed method showed good linear relationship (10.0-500 μg/kg), low method detection limits (0.219-1.42 μg/kg) and quantification limits (0.731-4.72 μg/kg), satisfactory relative recoveries (87.1-104%) with intra-day and inter-day RSDs in the ranges of 0.853-8.62% and 1.65-11.8%, respectively. The established method was successfully applied for the determination of six tetracyclines in eggs and chicken of different parts. The contents of tetracyclines in all samples were lower than their maximum residue limits.

CONCLUSIONS

A DLLME-HPLC method has been developed for the analysis of six tetracyclines in animal derived foods using ionic liquid and ethyl acetate as the extractant.

HIGHLIGHTS

The developed method is simple, sensitive, cost-effective and has strong anti-interference ability. This method has been successfully applied to the analysis of six tetracyclines in eggs and chicken.

Sensitive and selective determination of triclosan using visual spectroscopy

Triclosan is a commonly used biocide effective against bacterial and fungal infections. However, its overuse in pharmaceutical and personal care products has resulted in its abundance in the natural environment. The detection of triclosan by visual spectroscopy can be carried out using the azo-coupling reaction of diazonium complexes. However, the reaction is also common to other phenolic compounds and aromatic amines, posing significant challenge. In this work, we investigate the azo-coupling reaction of triclosan and several commonly occurring analogous compounds to develop an improved spectroscopic method for the selective determination of triclosan without interference. We find that the azo-coupling reaction between the diazotized derivative and the phenolic compounds is highly dependent on the pH of the reaction media. At pH 7.2, the absorbance of the azo dye product of triclosan shows a peak at 452 nm which has minimal interference from other phenolic azo-dye products with the exception of naphthol. Naphthol shows an interference corresponding to 58% of the analytical signal of equimolar triclosan concentration. To overcome this, we develop an analytical model for the simultaneous determination of triclosan and naphthol from mixed solutions of the compounds. A linear calibration plot from 1.7 to 34 µM was obtained for both triclosan and naphthol with limit-of-detection (LOD) of 0.62 µM and 1.03 µM respectively. The developed protocol was tested for the analysis of water samples collected from various environmental sources spiked with different concentrations of triclosan and naphthol. The samples were enriched by solid-phase-extraction which allowed a 50-fold enhancement in detection of triclosan. The average relative recovery of triclosan in real samples was found to be 98.6% .

Immobilization of unmodified aminoanthraquinone derivatives onto silica gel surface for solid-phase extraction and pre-concentration of Pb(II)

In this project, silica gel chemically bonded with derivatives of aminoanthraquinone were synthesized and characterized. Adsorbents 1,8-aminoanthraquinone-3-aminopropylsilica (SL1), 2-aminoanthraquinone-3-aminopropylsilica (SL2) and 1-aminoanthraquinone-3-aminopropylsilica (SL3) were produced and tested to adsorb heavy metal solutions including Pb(II) Cu(II) Zn(II) Cd(II) and Co(II). The concentrations of the adsorbed heavy metals solution were calculated by atomic adsorption spectrophotometry employing a batch method. The results showed that speed at 200 rpm for 30 min with pH 9 is the optimum condition for heavy metal adsorption. The result also indicated that adsorbent SL3 is the best adsorbent for Pb(II) at 82.5%, and the relative standard deviation (R.S.D.) was lower than 6%. The method detection limit was 1.1 µg L^-1 for Pb²⁺. In addition, Density Functional Theory (DFT) calculation results suggested that the adsorbent sensor formed stable complexes with Pb(II) through a large number of cation-dipole interactions. The method was also applied with satisfactory results to the pre-concentration of trace Pb(II) in environmental samples.

N-doped mesoporous carbon as a new sorbent for ultrasonic-assisted dispersive micro-solid-phase extraction of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene, from urine samples

This study aimed to optimize a new sample preparation method using N-doped mesoporous carbon sorbent for simultaneous measurement of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene. The samples were analyzed using high-performance liquid chromatography supplied with ultraviolet detector (HPLC-UV). N-doped mesoporous carbon sorbent was obtained via the hard template procedure. The synthesized nanosorbent was then characterized by transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and elemental analysis (CHN). The effective factors in the extraction of the studied biomarkers were examined by the Box-Behnken (BBD) methodology. Regarding the optimum conditions, the sketched calibration curve for naphthols was linear in the concentration levels of 1-600 µg L^-1 for human urine samples. The accuracy and reproducibility of the introduced method were determined using the relative recovery (RR %) and relative standard deviation (RSD %) tests on the fortified urine samples. RR% and RSD% were found to be 97.0-101.2% and 3.1-9.0%, respectively. The calculated method detection limit of the optimized procedure was 0.3 µg L^-1 and 0.5 µg L^-1 for 1-naphthol and 2-naphthol, respectively.

Recent Materials Developed for Dispersive Solid Phase Extraction

Solid phase extraction (SPE) is an analytical procedure developed with the purpose of separating a target analyte from a complex sample matrix prior to quantitative or qualitative determination. The purpose of such treatment is twofold: elimination of matrix constituents that could interfere with the detection process or even damage analytical equipment as well as enriching the analyte in the sample so that it is readily available for detection. Dispersive solid phase extraction (dSPE) is a recent development of the standard SPE technique that is attracting growing attention due to its remarkable simplicity, short extraction time and low requirement for solvent expenditure, accompanied by high effectiveness and wide applicability. This review aims to thoroughly survey recently conducted analytical studies focusing on methods utilizing novel, interesting nanomaterials as dSPE sorbents, as well as known materials that have been only recently successfully applied in dSPE techniques, and evaluate their performance and suitability based on comparison with previously reported analytical procedures.

A Critical Review on the Synthesis and Application of Ion-Imprinted Polymers for Selective Preconcentration, Speciation, Removal and Determination of Trace and Essential Metals from Different Matrices

The presence of toxic trace metals and high concentrations of essential elements in the environment presents a serious threat to living organism. Various methods have been used for the detection, preconcentration and remediation of these metals from biological, environmental and food matrices. Owing to the complexicity of samples, methods with high selectivity have been used for detection, preconcentration and remediation of these trace metals. These methods are achieved by the use of ion-imprinted polymers (IIPs) due to their impressive properties such as selectivity, high extraction efficiency, speciation capability and reusability. Because of the increase of toxic trace and essential metals in the environment, IIPs have attracted great use in analytical chemistry. This review, provide a brief background on IIPs and polymerization method that are used for their preparation. Recent applications of IIPs as adsorbents for preconcentration, removal, speciation and electrochemical detection of trace and essential metal is also discussed.

Ultrasound-assisted dispersive micro-solid-phase extraction based on N-doped mesoporous carbon and high-performance liquid chromatographic determination of 1-hydroxypyrene in urine samples

In this research, a new ultrasound-assisted dispersive micro-solid-phase extraction method based on N-doped mesoporous carbon sorbent followed by high-performance liquid chromatography equipped with diode array detector for trace measurement of 1-hydroxypyrene as a metabolite of exposure to polycyclic aromatic hydrocarbons was optimized. Herein, the hard template method was used for the preparation of N-doped mesoporous carbon sorbent. The prepared sorbent was characterized using the Brunauer-Emmett-Teller method, transmission electron microscopy, and elemental analysis. Parameters affecting the extraction of the target metabolite were investigated using the Box-Behnken design method. Considering optimum parameters, the plotted calibration curve for 1-hydroxypyrene was linearly correlated with the concentration span of 0.1-50 μg/L for urine media. The accuracy of the optimized procedure was examined through the relative recovery tests on the fortified urine specimens. The relative recoveries fell between 95 and 101%. The method detection limit of the proposed procedure was also calculated to be 0.03 μg/L.

Preparation and application of guanidyl-functionalized graphene oxide-grafted silica for efficient extraction of acidic herbicides by Box-Behnken design

A highly selective and efficient extraction material was synthesized through the functionalization of guanidyl onto the graphene oxide-grafted silica via a simple chemical modification, which was designed and proposed to improve the enrichment capacity for acidic herbicides. The extraction material was confirmed by scanning electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectrometry, thermal gravimetric analyzer and zeta potential analysis. Theoretical adsorption energies, static- and dynamic-state binding experiments, and comparative experiments with various adsorbents were investigated to elucidate the adsorption mechanism. The introduction of guanidyl endowed the sorbent with stronger Lewis base property and electron-donating ability, hence, excellent extraction recoveries for acidic herbicides could be obtained. Besides, electrostatic and π-π interactions were considered as two major driving impetuses in the adsorption process. Single-factor experiment and response surface methodology were utilized for the optimization of extraction and desorption conditions. Under the optimized conditions, the wide linearities were obtained with correlation coefficients ranging from 0.9904 to 0.9980, and the method detection limits were in the range of 0.5-2 μg L^-1. The relative standard deviation values of the recoveries of five different extractions were 3.0-7.1%. Coupled with high performance liquid chromatography, the as-proposed method was successfully applied to detect five acidic herbicides in Lycium barbarum (Goji). It turned out that the proposed method provided a promising perspective for the selective extraction and determination of polar acidic compounds in complex samples.

The conjunction of a new ultrasonic-assisted dispersive solid-phase extraction method with HPLC-DAD for the trace determination of diazinon in biological and water media

Herein, a new ultrasonic-assisted dispersive solid-phase extraction method was successfully developed for the trace detection of diazinon.

Preconcentration and ultra-trace determination of hexavalent chromium ions using tailor-made polymer nanoparticles coupled with graphite furnace atomic absorption spectrometry: ultrasonic assisted-dispersive solid-phase extraction

We describe ultrasonic assisted-dispersive solid-phase extraction based on tailor-made polymer (UA-DSPE-TMP) nanoparticles for selective extraction of Cr(vi) ions.