Trends in sorbent development for dispersive micro-solid phase extraction

A new SERS quantitative analysis strategy for ultratrace chloramphenicol with Fe3O4@MIP nanocatalytic probe

Three functional magnetic nanocatalytic probe, which integrates recognition, catalytic amplification, and separation enrichment, is a new approach to construct a simple, fast, highly selective, and sensitive analytical method. In this article, a new magnetic nanosurface molecularly imprinted polymer nanoprobe (Fe3O4@MIP) with trifunctionality was rapidly prepared using a microwave-assisted method with magnetic Fe3O4 nanoparticles as a substrate, chloramphenicol (CAP) as a template molecule, and methacrylic acid as a functional monomer. The characterized nanoprobe was found that could specifically recognize CAP, strongly catalyze the new indicator nanoreaction of fructose (DF)-HAuCl4. The gold nanoparticles (AuNPs) exhibit strong resonance Rayleigh scattering (RRS) and surface enhanced Raman scattering (SERS) effects. Upon addition of CAP, the SERS/RRS signals were linearly weakened. Accordingly, a new SERS/RRS analysis platform for highly sensitive and selective determination of CAP was constructed. The SERS linear range was 0.0125-0.1 nmol/L, with detection limit (DL) of 0.004 nmol/L CAP. Furthermore, it could be combined with magnet-enriched separation to further improve the sensitivity, with a DL of 0.04 pmol/L CAP. The SERS method has been used for the determination of CAP in real samples, with relative standard deviations of 2.37-9.89 % and the recovery of 95.24-107.1 %.

Molecularly imprinted polymers in the analysis of chlorogenic acid: A review

Chlorogenic acid, a phenolic compound, is prevalent across various plant species and has been known for its pharmacological advantages. Health care experts have identified chlorogenic acid as a potential biomarker for treatment of a wide range of illnesses. Therefore, achieving efficient extraction and analysis of chlorogenic acid from plants and their products has become essential. Molecularly imprinted polymers (MIPs) are highly effective adsorbent for the extraction of chlorogenic acid from complex matrices. Currently, there is a lack of comprehensive review article that consolidate the methods utilized for the purification of chlorogenic acid through molecular imprinting. In this context, we have surveyed the common approaches employed in preparing MIPs specifically designed for the analysis of chlorogenic acid, including both conventional and newly developed. This review discusses the advantages, limitations of polymerization techniques and proposed strategies to produce more efficient MIPs for chlorogenic acid enrichment in complex samples. Additionaly, we present advanced imprinting methods for designing MIPs, which improve the adsorption capacity, sensitivity and selectivity towards chlorogenic acid.

Heteroatom cobalt-based metal-organic framework and reduced graphene oxide nanocomposite for dispersive solid phase extraction of caffeine from exhaled breath condensate samples of premature infants prior to HPLC-PDA

A cobalt-based metal-organic framework and graphene oxide were combined to prepare a new nanocomposite for extracting of caffeine from exhaled breath condensate (EBC) samples. Dispersive micro solid phase extraction of caffeine was conducted using the nanocomposite as a sorbent by adding 10 mg of it to the sample solution and vortexing for 3 min. After extracting of the analyte, it was eluted using the mobile phase. The analyte was then analyzed using high performance liquid chromatography-photodiode array detector. Under optimal conditions, the limit of detection, limit of quantification, and linear range of the calibration curve were found to be 1.7, 5.9, and 10-500 µg/L, respectively. To assess the precision of the method, five replicates of standard solutions containing caffeine at two different concentration levels (50 and 100 µg/L) were tested. The relative standard deviations for intra- and inter-day precisions ranged from 4.3 to 6.8 %. The applicability of the method was demonstrated by analyzing the samples obtained from premature infants undergoing caffeine treatment and caffeine concentrations were 4.9 ± 0.6, 2.7 ± 0.2 µg/L in the EBC samples of who were under treatment by a 5-mg dose. Also, caffeine concentrations were 5.9 ± 0.3 and 18 ± 0.6 µg/L in the the infants who obtained the 10-mg and 25-mg doses, respectively. The results indicated a satisfactory, extraction recovery of 86 % showcasing the method's reliability and effectiveness in analyzing real samples.

Removal of aflatoxin M1 in milk using magnetic laccase/MoS2/chitosan nanocomposite as an efficient sorbent

The current study tries to find the impact of the integration of laccase enzyme (Lac) onto magnetized chitosan (Cs) nanoparticles composed of molybdenum disulfide (MoS2 NPs) (Fe3O4/Cs/MoS2/Lac NPs) on the removal of AFM1 in milk samples. The Fe3O4/Cs/MoS2/Lac NPs were characterized by FT-IR, XRD, BET, TEM, FESEM, EDS, PSA, and VSM analysis. The cytotoxic activity of the synthesized nanoparticles in different concentrations was evaluated using the MTT method. The results show that the synthesized nanoparticles don't have cytotoxic activity at concentrations less than 20 mg/l. The ability of the prepared nanoparticles to remove AFM1 was compared by bare laccase enzyme, MoS2, and Fe3O4/Cs/MoS2 composite, indicating that the Fe3O4/Cs/MoS2/Lac NPs the highest adsorption efficiency toward AFM1. Besides, the immobilization efficiency of laccase with a concentration range of 0.5-2.0 was investigated, indicating that the highest activity recovery of 96.8% was obtained using 2 mg/ml laccase loading capacity. The highest removal percentage of AFM1 (68.5%) in the milk samples was obtained by the Fe3O4/Cs/MoS2/Lac NPs at a contact time of 1 h. As a result, Fe3O4/MoS2/Cs/Lac NPs can potentially be utilized as an effective sorbent with high capacity and selectivity to remove AFM1 from milk samples.

Nickel-manganese-cobalt tetragonal spinel ternary oxide nanocomposite as an effective adsorbent for dispersive solid phase micro-extraction of cadmium in food and water samples

Nickel-manganese-cobalt tetragonal spinel ternary oxide nanocomposite (NMC-TSO) was synthesized. It was utilized as an efficient sorbent for the dispersive solid phase microextraction (D-SPμE) without vortexing of cadmium. The analysis of the cadmium was carried out by FAAS. The effective analytical parameters including pH (6) contact times (no vortexing), sample volume (70 mL), eluent volume (3 mL of 2 mol L-1 HCl), linear dynamic ranges (1.07-85.7 μg L-1), and re-useability (33) on the D-SPμE efficiency were investigated. The PF, RSD% and LOD of the D-SPμE for cadmium were 23.3, ≤ 2.8% and 0.49 μg L-1, respectively. The tolerable concentrations of Ca2+, Mg2+, K+ and Na+ on Cd(II) were 50,000 mg L-1, 50,000 mg L-1, 25,000 mg L-1 and 7500 mg L-1, respectively. The method was accurated by analysis of food and water certificate reference materials (NW-TMDA-54.6 Lake water, SPS-WW1 121 Batch wastewater, 1573a Tomato Leaves and TORT-3 Lobster Hepatopancreas) and - recovery experiments. The D-SPμE-FAAS method was applied for the cadmium determination in dam water, wastewater, river water, well water, sea water, tea, cacao, nut, bitter chocolate, rice, leek, cinnamon and parsley.

Exploration of novel solid-phase extraction modes for analysis of multiclass emerging contaminants

Solid-phase extraction (SPE) has gained an essential role in environmental analytical chemistry. Classic off-line SPE coupled with LC-MS/MS systems creates powerful analytical procedures for ultratrace analysis of contaminants of emerging concern (CECs) in water. But, being associated with tedious work and large consumption of materials, alternative SPE modes are becoming interesting. As so, the study focuses on development, evaluation, and overall comparison of established and novel SPE modes. Off-line SPE, dispersive micro SPE (DMSPE), and 'fast' single-pump on-line SPE were explored, using commercially available sorbents. Their efficiency was evaluated on their performance in water analysis of 20 multiclass CECs. Hydrophilic-lipophilic sorbent and mixture of C18/C8 sorbents were the best choice for off-line and DMSPE, respectively. All optimized SPE modes coupled with UHPLC-MS/MS reached environmentally-relevant limits of detection (LODs 0.1-12 ng L-1), acceptable repeatability (<20 % RSD), and exhibited less than ±30 % matrix effects in real river water sample. Among all, on-line SPE showed a potential to fully replace the well-established off-line SPE and even improve analytical performance. This was due to the best repeatability (<10 % RSD), automatization, simplicity, the highest multiplexing capacity, as well as comparable LODs of <2 ng L-1. DMSPE is, on the other hand, the most innovative and could be seen as a quick and green alternative to off-line SPE for determination of semi-to-nonpolar CECs, but within sub-10 ng L-1 range. Overall, the study shows workflow for the exploration of important and promising sample pretreatment techniques in water analysis. Comparison of the developed three SPE-UHPLC-MS/MS methods suggests that alternative SPE modes can compete with the well-established off-line SPE and can even improve the analysis quality if properly applied.

Advances and Applications of Hybrid Graphene-Based Materials as Sorbents for Solid Phase Microextraction Techniques

The advancement of traditional sample preparation techniques has brought about miniaturization systems designed to scale down conventional methods and advocate for environmentally friendly analytical approaches. Although often referred to as green analytical strategies, the effectiveness of these methods is intricately linked to the properties of the sorbent utilized. Moreover, to fully embrace implementing these methods, it is crucial to innovate and develop new sorbent or solid phases that enhance the adaptability of miniaturized techniques across various matrices and analytes. Graphene-based materials exhibit remarkable versatility and modification potential, making them ideal sorbents for miniaturized strategies due to their high surface area and functional groups. Their notable adsorption capability and alignment with green synthesis approaches, such as bio-based graphene materials, enable the use of less sorbent and the creation of biodegradable materials, enhancing their eco-friendly aspects towards green analytical practices. Therefore, this study provides an overview of different types of hybrid graphene-based materials as well as their applications in crucial miniaturized techniques, focusing on offline methodologies such as stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), pipette-tip solid-phase extraction (PT-SPE), disposable pipette extraction (DPX), dispersive micro-solid-phase extraction (d-µ-SPE), and magnetic solid-phase extraction (MSPE).

Nitrophenols in the environment: An update on pretreatment and analysis techniques since 2017

Nitrophenols, a versatile intermediate, have been widely used in leather, medicine, chemical synthesis, and other fields. Because these components are widely applied, they can enter the environment through various routes, leading to many hazards and toxicities. There has been a recent surge in the development of simple, rapid, environmentally friendly, and effective techniques for determining these environmental pollutants. This review provides a comprehensive overview of the latest research progress on the pretreatment and analysis methods of nitrophenols since 2017, with a focus on environmental samples. Pretreatment methods include liquid-liquid extraction, solid-phase extraction, dispersive extraction, and microextraction methods. Analysis methods mainly include liquid chromatography-based methods, gas chromatography-based methods, supercritical fluid chromatography. In addition, this review also discusses and compares the advantages/disadvantages and development prospects of different pretreatment and analysis methods to provide a reference for further research.

The determination of thallium in the environment: A review of conventional and advanced techniques and applications

Thallium (Tl) is a potential toxicity element that poses significant ecological and environmental risks. Recently, a substantial amount of Tl has been released into the environment through natural and human activities, which attracts increasing attention. The determination of this hazardous and trace element is crucial for controlling its pollution. This article summarizes the advancement and progress in optimizing Tl detection techniques, including atomic absorption spectroscopy (AAS), voltammetry, inductively coupled plasma (ICP)-based methods, spectrophotometry, and X-ray-based methods. Additionally, it introduces sampling and pretreatment methods such as diffusive gradients in thin films (DGT), liquid-liquid extraction, solid phase extraction, and cloud point extraction. Among these techniques, ICP-mass spectrometry (MS) is the preferred choice for Tl detection due to its high precision in determining Tl as well as its species and isotopic composition. Meanwhile, some new materials and agents are employed in detection. The application of novel work electrode materials and chromogenic agents is discussed. Emphasis is placed on reducing solvent consumption and utilizing pretreatment techniques such as ultrasound-assisted processes and functionalized magnetic particles. Most detection is performed in aqueous matrices, while X-ray-based methods applied to solid phases are summarized which provide non-destructive analysis. This work improves the understanding of Tl determination technology while serving as a valuable resource for researchers seeking appropriate analytical techniques.

Vortex-assisted dispersive micro-solid-phase extraction using silica-supported Fe2O3-modified khat (Catha edulis) biochar nanocomposite followed by GC-MS for the determination of organochlorine pesticides in juice samples

In this paper, dispersive micro-solid phase extraction technique was developed for the purpose of extracting and preconcentrating organochlorine pesticide residues in juice samples before their separation and quantitative analysis by gas chromatography-mass spectrometry. A sorbent composed of a silica-supported Fe2O3-modified khat leftover biochar nanocomposite (SiO2-Fe2O3-KLBNC) was implemented in the process. To improve the dispersion of the sorbent in the solution, vortex mixer was employed. Experimental parameters influencing the performance of the method were optimized, and the optimal conditions were established. With these conditions, linear dynamic ranges ranged from 0.003 to 100.0 ng/mL were achieved, with a correlation coefficient (r2) ≥ 0.9981. The limits of detection and quantification, determined by signal-to-noise ratios of 3 and 10, respectively, were found to be in the ranges of 0.001-0.006 ng/mL and 0.003-0.020 ng/mL. Intra- and inter-day precision, values ranging from 0.3-4.8% and 1.7-5.2% were obtained, respectively. The matrix-matched extraction recoveries demonstrated favorable outcomes, falling within the range of 83.4-108.3%. The utilization of khat leftover as an adsorbent in contemporary sample preparation methodologies offers a cost-effective alternative to the currently available, yet expensive, adsorbents. This renders it economically viable, particularly in resource-constrained regions, and is anticipated to witness widespread adoption in the coming future.

Synthesis and evaluation of a chitosan nanomaterial as efficient sorbent for determination of fungicide residues in waters and wine by liquid chromatography high resolution mass spectrometry

In the present study a novel, cost-effective, environmentally friendly, and efficient analytical method was developed to analyze fungicide residues in water and wine. The method relies on the application of a newly developed sorbent nanomaterial named Nano-Cs-NAT, synthesized by modifying chitosan, a naturally occurring, low-cost polysaccharide, through grafting with two acrylic monomers and a cross-linker. Nano-Cs-NAT was introduced as analytical sorbent for Dispersive Micro Solid Phase Extraction (D-μ-SPE) before Liquid Chromatography-Orbitrap High-Resolution Mass Spectrometry (LC-Orbitrap HRMS) analysis of twelve fungicides commonly used in viticulture (among the others, triazoles, strobilurines and N-substituted imidazoles). Characterization of the sorbent was conducted, confirming the successful acrylation of chitosan. A multivariate approach was employed to optimize D-μ-SPE extraction parameters. The material was found to be highly effective in simultaneously purifying and concentrating the target analytes, enhancing overall analytical efficiency and sensitivity. The Nano-Cs-NAT-D-μ-SPE-LC-Orbitrap-HRMS method was thoroughly validated, exhibiting good recoveries (72-104%), reproducibility (average RSD ≤ 6%) and repeatability (average RSD ≤ 7%). It also achieved low limits of detection (LOD) in river water (average LOD of 0.04 μg L-1) and wine (average LOD of 0.72 μg kg-1), highlighting its potential for routine fungicide residue analysis. This developed method addresses environmental and food safety concerns by providing an efficient solution for detecting fungicide residues in waters and wine.

An efficient deep eutectic magnetic nano gel for rapid ultrasound-assisted dispersive µ-solid phase extraction of residue of tetracyclines in food samples

In the present study, a magnetic nano gel as the sorbent which is the combination of octatonic acid: cumarin as eutectic solvent and Fe3O4@SiO2 was introduced as the sorbent in ultrasound-assisted dispersive µ-solid phase extraction process coupled with high performance liquid chromatography with photo diode array detector for simultaneous separation and determination of tetracyclines residues in food samples. FT-IR, SEM, VSM were used for the characterization of the synthetized magnetic nano gel. Under obtained optimum conditions, the obtained linear ranges were 1.5-500 (µg L-1), 2.5-750 (µg L-1), 2-750 (µg L-1), and 2.5-500 (µg L-1) for tetracycline, oxytetracycline, chlortetracycline, and doxycycline, respectively. Moreover, the below level of quantification (BLQ) (based on S/N = 3) of 0.47 µg L-1, 0.11 µg L-1, 0.85 µg L-1, 0.66 µg L-1, 0.81 µg L-1 and the limit of quantification (based on S/N = 10) of 1.61, 2.74, 2.23 (µg L-1), and 2.66 were achieved for tetracycline, oxytetracycline, chlortetracycline, and doxycycline, respectively. The intra-day and inter-day precision (%) of the procedure were less than 3.2 and 3.8, respectively. The recoveries over 95% confirmed high sufficiency of the proposed method for application in complex matrices such as honey, milk, and egg.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05798-w.

Optimization and synthesis of a novel sorbent composite based on magnetic chitosan-amine-functionalized bimetallic MOF for the simultaneous dispersive solid-phase microextraction of four aflatoxins in real water, herbal distillate, and food samples

Aflatoxins (AFs), an important category of pollutants, are formed in many foods and adversely affect human health. Therefore, their determination is critical to ensuring human food health. An efficient dispersive solid-phase microextraction technique was developed as a simple and straightforward sample preparation technique for determination of four aflatoxins using a high-performance liquid chromatography (HPLC) fluorescence detector. A novel efficient, green sorbent for extracting AFs was synthesized based on hydrothermal and chemical strategies. The amounts of three sorbent components were optimized using a mixture design (simplex lattice design), including 14 experiments. The optimal amount of amino-bimetallic Fe/Ni-MIL-53 nanospheres, chitosan, and magnetic Fe3O4 nanoparticles as sorbent components was 0.87, 0.67, and 0.47 g, respectively. Also, various factors affecting the process of AF determination were studied and optimized in two successive experimental designs, including the definitive screening design and the Box-Behnken design. Under optimal conditions, the linear ranges for measuring aflatoxin B1, aflatoxin B2, aflatoxin G1, and aflatoxin G2 were 0.05-82.6, 0.07-86.4, 0.08-85.7, and 0.07-89.5 ng mL-1, respectively. The relative standard deviations under inter-day and intra-day conditions for measuring AFs at three analyte concentrations were determined in triplicate analysis and were in the ranges of 3.7-4.6% and 4.9-6.1% for water sample analysis, respectively. The qualitative detection limits for determining AFs were between 0.01 and 0.05 ng mL-1. The pre-concentration factor of the method for measuring AFs ranged from 739.7 to 802.1. The proposed method was used for determining AFs in several real samples, including herbal distillate, black tea, corn, and real water samples. The relative recovery and standard deviation were 87.8-97.8% and 4.10-6.82%, respectively.

Evaluation of reduced graphene oxide-based nanomaterial as dispersive solid phase extraction sorbent for isolation and purification of aflatoxins from poultry feed, combined with UHPLC-MS/MS analysis

Poultry feed comprises cereals and their by-products and is vulnerable to aflatoxins contamination. This study utilised reduced graphene oxide-titanium dioxide (rGO-TiO2) nanomaterial as a dispersive solid phase extraction (d-SPE) adsorbent to extract, enrich and purify aflatoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1 and aflatoxin G2). The synthesis of rGO-TiO2 nanomaterials through hydrothermal process and characterisation by transmission electron microscopy, scanning electron microscopy, Brunauer-Emmett-Teller (BET) and X-ray diffraction reveals that the nanomaterials have a single-layer structure embedded with TiO2 nanoparticles. The matrix-spiked technique was employed for the extraction process, optimisation of d-SPE, and analytical method validation. The most appropriate extraction solvent was acetonitrile/water/formic acid (79/20/1, v/v/v), with 30 min of extraction time assisted by ultra-sonication. The optimised d-SPE parameters were: 50 mg of rGO-TiO2 as sorbent amount, 2% methanol as the sample loading solvent, 30 min as adsorption time, and absolute ethanol as the washing reagent. The d-SPE method exhibited good desorption efficiency with 3 mL of acetonitrile/formic acid (99/1, v/v) and 20 min desorption time. After validation, the UHPLC-MS/MS analytical method has an acceptable range of specificity, linearity (R2 ≥ 0.999), sensitivity (LOQ 0.04-0.1 µg kg-1), recoveries (74-105% at three matrix-spiked levels) and precision (RSD 1.5-9.6%). Poultry feed samples (n = 12) were pretreated by this method to extract, enrich and analyse aflatoxins, which were detected in all poultry feed samples. The contamination levels were within the permissible limits.

Magnetic layered double hydroxides for the sensitive dispersive solid phase microextraction of hippuric acid in urine samples prior to HPLC-UV analysis

The core- shell structural layered double hydroxide (Fe₃O₄-SiO₂-EN@Zn-Al-LDH) was successfully synthesized and applied as a solid sorbent in the magnetic dispersive micro solid-phase-extraction (M-DµSPE) method. It was combined with high-performance liquid chromatography for the trace analysis of hippuric acid (HA) from urine samples. The obtained magnetic layered double hydroxides (LDHs) were characterized by XRD, FT-IR, VSM, FE-SEM, and BET techniques. The characterization analysis indicated that Fe₃O₄- SiO₂- EN@ Zn-Al-LDH has a sufficient surface area and good saturation magnetism. The affecting variables on the extraction of HA by the proposed method were optimized. Excellent adsorption capacity (127.8 mg g^-1), wide linearity dynamic range (0.015-500 µg mL^-1), and satisfactory limits of detection and quantification (0.055 and 0.014 µg mL^-1, respectively) could be obtained under optimum conditions. The good repeatability and low relative standard deviation (7.2 %), low carry-over (2.7%), good matrix effect (93.6%), high reusability (up to 19 times), and an acceptable percent recovery value (97.2%) proved the selectivity and applicability of the proposed method for the extraction of the trace levels of HA in real urine samples.

Solvent-assisted dispersive micro-solid phase extraction of bisphenols using iron(III) thenoyltrifluoroacetonate complex (Fe(TTA)3) as a new nanostructured sorbent: a proof of concept

In this work, we describe for the first time the use of iron(III) thenoyltrifluoroacetonate complex (Fe(TTA)₃) as a novel sorbent for solvent-assisted dispersive micro-solid phase extraction (SA-dμSPE) of bisphenols from water samples. The extraction procedure is based on the formation of nanoparticles in situ following the rapid injection of a methanolic solution of Fe(TTA)₃ into the stirred aqueous sample. Herein, the synthesis of Fe(TTA)₃ and study of the essential parameters of the preparative procedure are described. The optimized procedure allowed for efficient enrichment of bisphenols from various water samples, chosen as model contaminants and matrix, within 2.5 min. The sorbent was collected by centrifugation, dissolved in methanol, and injected to perform HPLC with spectrophotometric detection. The limits of detection and quantification obtained ranged from 1.0-3.1 and 3.1-7.5 μg L^-1, respectively. Intraday and interday precisions of <7% relative standard deviation (RSD) and <8% RSD with analyte recoveries ranging between 70-117% (103.8% on average) were obtained for the analysis of river water, wastewater treatment plant effluent, and bottled water.

Efficient dispersive solid-phase extraction of methylprednisolone from exhaled breath of COVID-19 patients

In the current study, bismuth ferrite nano-sorbent was synthesized and utilized as a sorbent for the dispersive solid-phase extraction of methylprednisolone from exhaled breath samples. The size and morphology of the nano-sorbent were characterized by X-ray diffraction analysis and scanning electron microscopy. Following its desorption with acetonitrile, methylprednisolone was quantified by a high-performance liquid chromatography-ultraviolet detector. Factors affecting the extraction of methylprednisolone were optimized. Under optimized experimental conditions, a linear relationship between the analytical signals and methylprednisolone concentration was obtained in the range of 0.001-0.2 μg mL^-1 for exhaled breath condensate samples and 0.002-0.4 μg per filter for filter samples. A pre-concentration factor of 6.4-fold, corresponding to an extraction recovery of 96.0%, was achieved. The validated method was applied for the determination of methylprednisolone in real samples taken from the exhaled breath of COVID-19 patients under mechanical ventilation.

Dispersive solid phase extraction of metronidazole and clarithromycin from human plasma using a β-cyclodextrin grafted polyethylene polymer composite

In this work, for the first time, a polymeric composite based on β-cyclodextrin grafted with polyethylene has been prepared through ball milling and used as an efficient sorbent for dispersive solid phase extraction of metronidazole and clarithromycin from plasma samples. The prepared sorbent was characterized using Fourier transform infrared spectrophotometry, X-ray diffraction, and scanning electron microscopy. In the extraction process, after precipitating the proteins, the sorbent was added into the sample solution, and the mixture was vortexed to facilitate and speed up the sorption of the analytes onto the sorbent surface. After centrifuging, the sorbent particles were contacted with methanol to elute the analytes under the vortexing process. After this step, an aliquot of the eluate was taken and injected into high-performance liquid chromatography-diode array detector for quantitative analysis. Under the optimum extraction conditions, the extraction recoveries for metronidazole and clarithromycin were 76 and 83%, respectively. The limits of detection were 2.6 and 2.2 ng/ml for metronidazole and clarithromycin, respectively. The repeatability of the offered approach, expressed as relative standard deviation, was equal to or less than 4.7%. Finally, the method was successfully applied to plasma samples of the patients treated with metronidazole and clarithromycin.

Magnetic solid-phase extraction of warfarin and gemfibrozil in biological samples using polydopamine-coated magnetic nanoparticles via core-shell nanostructure

Herein, polydopamine-coated Fe₃ O₄ spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe₃ O₄ ) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe₃ O₄ . The prepared polydopamine-coated Fe₃ O₄ spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1-200.0 μg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026-0.055 μg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089-0.185 μg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%-3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.

Application of MIL-53(Al)-NH2 as a Dispersive Microsolid-Phase Extraction Material for Determination of Cyclophosphamide in Urine by High-Performance Liquid Chromatography

In this paper, an aluminum-based metal-organic framework (MIL-53(Al)-NH₂) was synthesized and employed as a well-known and efficient dispersive microsolid-phase extraction (Dμ-SPE) sorbent for reliable determination of cyclophosphamide in urine samples by the high-performance liquid chromatography (HPLC) technique. The synthesized MIL-53(Al)-NH₂ was characterized by FT-IR, PXRD, FE-SEM, and EDS for more details. Then, the effective parameters of the preconcentration and extraction of urinary cyclophosphamide including the amount of the solid sorbent, the pH of the sample, sample volume, extraction and desorption time, and the type and volume of elution solvent were thoroughly investigated and optimized. According to the results, a linear dynamic range of 0.14-120 μg mL^-1 with a good correlation coefficient (R ² = 0.998) and a limit of detection (LOD) of 0.05 μg mL^-1 were obtained with intra- and interday relative standard deviations (n = 9) of 3.13 and 3.99% in optimized conditions, respectively. Furthermore, the absolute recovery of urinary cyclophosphamide at three concentrations (0.5, 50.0, and 100.0 μg mL^-1) was 94.0%. Finally, the optimal condition of the developed method was successfully applied to the extraction and analysis of cyclophosphamide from the real urine samples with satisfactory recovery (94.0-97.0%) and acceptable precision (<4.1%). The findings proved that MIL-53(Al)-NH₂ can be utilized as a suitable adsorbent for highly reliable extraction of cyclophosphamide in biological matrices.

Selective Extraction of Trace Arsenite Ions Using a Highly Porous Aluminum Oxide Membrane with Ordered Nanopores

Metal ion extraction and determination at trace level concentration are challenging due to sample complexity or spectral interferences. Herein, we prepared a through-hole aluminum oxide membrane (AOM) by electrochemical anodization of aluminum substrates. The prepared AOM was characterized by scanning electron microscopy, surface area analysis, porosity measurements, and X-ray photoelectron spectroscopy. The AOM with ordered nanopores was highly porous and possess inherent binding sites for selective arsenite sorption. The AOM was used as a novel sorbent for solid-phase microextraction and preconcentration of arsenite ions in water samples. The AOM's sub-micrometer thickness allows water molecules to flow freely across the pores. Before instrumental determination, the suggested microextraction approach removes spectral interferents and improves the analyte ion concentration, with a detection limit of 0.02 μg L^-1. Analyzing a standard reference material was used to validate the procedure. Student's t-test value was less than critical Student's t-value of 4.303 at a 95% confidence level. With coefficients of variation of 3.25%, good precision was achieved.

Conductive Polymer-Based Nanocomposites as Powerful Sorbents: Design, Preparation and Extraction Applications

Conductive polymers as composite materials have been attracted tremendous attention due to their versatile and excellent features such as tunable conductivity, facile synthesis and fabrication, high chemical and thermal stability etc. These characteristics make them versatile and let them being used in numerous fields including microelectronics, optics and biosensors. Throughout the mentioned fields, conductive polymers particularly perform as effective sorbents. Although tremendous efforts have been put into this topic, to the best of our knowledge, a comprehensive up-to-date review on the applications of conductive polymers as efficient sorbents has not been reported. The main objective of this paper is to make a significant contribution to the recent literature toward the synthesis and extraction applications of conductive polymers as efficient sorbents.

Stir bar sorptive-dispersive microextraction by a poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent for the determination of tricyclic antidepressants and their main active metabolites in human urine

A poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent was used for the rapid and sensitive determination of tricyclic antidepressants and their main active metabolites in human urine. This material was characterized by magnetism measurements, zeta potential, scanning electron microscopy, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The proposed analytical method is based on stir bar sorptive-dispersive microextraction (SBSDME) followed by liquid chromatography-tandem mass spectrometry. The main parameters involved in the extraction step were optimized by using the response surface methodology as a multivariate optimization method, whereas a univariate approach was employed to study the desorption parameters. Under the optimized conditions, the proposed method was properly validated showing good linearity (at least up to 50 ng mL-1) and enrichment factors (13-22), limits of detection and quantification in the low ng L-1 range (1.4-7.0 ng L-1), and good intra- and inter-day repeatability (relative standard deviations below 15%). Matrix effects were observed for the direct analysis of urine samples, but they were negligible when a 1:1 v/v dilution with deionized water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, one of them consuming a prescribed drug for depression that tested positive for clomipramine and its main active metabolite. Quantitative relative recoveries (80-113%) were obtained by external calibration. The present work expands the applicability of the SBSDME to new analytes and new types of magnetic sorbents.

Developments of Microextraction (Extraction) Procedures for Sample Preparation of Antidepressants in Biological and Water Samples, a Review

Antidepressants are an important class of drugs to treat various types of depression. The determination of antidepressants is crucial in biological samples to control adverse effects in humans and study pharmacokinetics and bioavailability. Direct measurement of antidepressants in biological and water samples is a considerable challenge for analysts due to their low concentration, the high matrix effects of real samples, and the presence of metabolites of these drugs in biological samples. The challenge leads to using sample preparation processes as a critical step in determining antidepressants. Extraction and microextraction procedures have been widely utilized as sample preparation procedures for these drugs. The purposes of extraction or microextraction methods for antidepressant medications are to preconcentrate the analyte, reduce the matrix effects, increase the selectivity of the procedures, and convert the sample to a suitable format for introducing it into detection systems. In the review, the various extraction and microextraction methods of these drugs in biological, real water, and wastewater samples were investigated. The theory of each technique was briefly addressed to understand the features and factors affecting each method. The extraction and microextraction methods were classified based on their application for antidepressants, and the advantages and disadvantages of each technique were reviewed. The new developments to overcome the limitations of each procedure were discussed. The investigation indicated the number of applications of liquid-phase microextraction for extracting antidepressants has been almost equal to that of solid-phase microextraction.

In situ adsorbent formation based dispersive micro-solid phase extraction using a deep eutectic solvent as an elution solvent for the extraction of some pesticides from honey samples prior to GC-MS analysis

In this work, a simple, inexpensive, green, and fast dispersive micro-solid phase extraction method has been developed for the extraction of several pesticides from honey samples. In this approach, a solution of curcumin was prepared in ethanol and it was dispersed into a sample solution with the aid of a syringe. Curcumin was precipitated in the sample solution as tiny particles and the analytes were adsorbed onto them. After centrifugation the adsorbed analytes were eluted with tetrabutylammonium chloride:dichloroacetic acid deep eutectic solvent. The dissolved analytes in the deep eutectic solvent were analyzed by gas chromatography-mass spectrometry. Parameters affecting the extraction efficiency of the method including sorbent amount, dispersive solvent type and volume, elution solvent type and volume, salting out effect, and sonication time were investigated. Extraction recovery of the method was obtained in the range of 70-83%. Also wide calibration ranges and low detection limits (0.22-0.81 ng g^-1) were obtained. Relative standard deviation values for intra- and inter-day precisions were ≤10.2% for all analytes at a concentration of 5 ng g^-1 of each (n = 6). Finally, ten honey samples were analyzed and data showed that all of the studied samples were free of the analytes.

Insights into Paraben Adsorption by Metal-Organic Frameworks for Analytical Applications

Metal-organic frameworks (MOFs) are attractive materials used as sorbents in analytical microextraction applications for contaminants of emerging concern (CECs) from environmental liquid matrices. The demanding specs for a sorbent in the analytical application can be comprehensively studied by considering the interactions of the target analytes with the frameworks by the use of single-crystal X-ray diffraction, computational analysis, and adsorption studies, including the kinetic ones. The current study intends a better understanding of the interactions of target CECs (particularly, propylparaben (PPB) as a model) and three Zn-based layered pillared MOFs: CIM-81 [Zn₂(tz)₂(bdc)] (Htz = 1,2,4-triazole and H₂bdc = 1,4-benzenedicarboxylic acid) and their amino derivatives [Zn₂(NH₂-tz)₂(bdc)] CIM-82 and [Zn₂(tz)₂(NH₂-bdc)] CIM-83 (NH₂-Htz = 3-amino-1,2,4-triazole and NH₂-H₂bdc = 2-amino-1,4-benzenedicarboxylic acid). The crystal structures of the two solvate compounds (dma@CIM-81 (dma = dimethylacetamide) and acetone@CIM-81) were solved by single-crystal X-ray diffraction to determine the points of interaction between the framework and the guest molecules. They also served as a starting point for the computational modeling of the PPB@CIM-81 compound, showing that up to two PPB molecules can be hosted in one of the pores, while only one can be trapped in the second pore type, leading to a maximum theoretical capacity of 291.9 mg g^-1. This value is close to the value obtained by the adsorption isotherm experiment for CIM-81 (283 mg g^-1). This value is, by far, higher than those previously reported for other materials for the removal of PPB from water, and also higher than the experimental values obtained for CIM-82 (54 mg g^-1) and CIM-83 (153 mg g^-1). The kinetics of adsorption is not very fast, with uptake of about 40% in 3 h, although a 70% release in methanol is achieved in 1 h. In addition, a further comparison of performance in analytical microextraction (requiring only 10 mg of CIM-81) was carried out together with chromatographic analysis to support all insights attained, with the method being able to monitor CECs as low as μg L^-1 levels in complex environmental water samples, thus performing successfully for water monitoring even in multicomponent scenarios.

Application of curcumin as a green and new sorbent in deep eutectic solvent-based dispersive micro-solid phase extraction of several polycyclic aromatic hydrocarbons from honey samples prior to gas chromatography-mass spectrometry determination

A green, simple, and efficient dispersive micro-solid phase extraction method was developed for the extraction of polycyclic aromatic hydrocarbons from honey samples. In this method, for the first time, curcumin was used as an efficient and green sorbent to extract the analytes from the sample. After that the adsorbed analytes were eluted using a deep eutectic solvent prepared by mixing tetrabutylammonium chloride: ethylene glycol and analyzed by gas chromatography-mass spectrometry. Important experimental factors affecting adsorption and desorption steps of the method were optimized and under optimal experimental conditions, low limits of detection (0.14-0.37 ng/g) and quantification (0.49-1.3 ng/g), wide linear range (1.3-500 ng/g) with a coefficient of determination ≥0.994 were obtained. Relative standard deviation values for intra- and interday precisions were ≤7.5% for all of the analytes at a concentration of 2 ng/g for each analyte (n = 6). Extraction recovery of the method was in the range of 72-81%. Finally, 20 honey samples were analyzed and the analytes were successfully detected. The method is environment friendly because of the use of curcumin as a sorbent. Also, biodegradability of the used deep eutectic solvent components is another advantage of the method.