Dispersive Solid-phase Extraction Procedure Research Articles

In situ-floating organic dispersive solid-phase extraction based on putrescine as a new adsorbent for the extraction of ions from crude oil prior to ICP-MS

ABSTRACT Quantification of ions in complex matrices like crude oil is an outstanding issue because of the high complexity of the sample. Herein, a facile, reliable, and precise floating dispersive solid-phase extraction procedure was introduced for the extraction of several ions (B, Ca, Cd, Cu, Cr, Ag, Fe, Mn, Ni, Na, Ba, Mg, Al, Si, Sn, Ti, Mo, V, Pb, Zn, P, and K) in which the need for adding complexing agent for the extraction of ions, centrifugation for separation of adsorbent, and shaker to enhance the contact area of the sample solution with absorbent was eliminated. These advantages were provided by using putrescine as the absorbent for the extraction of the analytes. To reach this goal, a proper amount of putrescine was dissolved in ethanol and injected into a diluted crude oil solution. During this step, putrescine formed stable complexes with the ions and extracted them from the solution and collected on top of the solution easily. The floated phase was collected by a spatula, and the extracted ions were determined by inductively coupled plasma mass spectrometry. Validation parameters of this method showed that low limits of detection (0.003–3.62 ng g−1) and quantification (0.009–12.0 ng g−1), broad linear range (12.0–80,000 ng g−1), acceptable relative standard deviation (≤5.3%) for intra- and inter-day precisions and high extraction recovery (72–90%) were the features of the method. The method was successful in the determination of the analytes in real crude oil samples.

Validation of an efficient analytical method for quantification of tetracycline antibiotic residues in egg samples along with investigating their decontamination using ultraviolet waves

ABSTRACT This study describes the development and application of a dispersive solid-phase extraction procedure combined with dispersive liquid – liquid microextraction for the extraction of tetracycline antibiotics from egg samples. In this method, a bio-metal organic framework was prepared and used in extraction of the analytes from sample solution. In this method, the sorbent synthesis was relatively easy and its crosslinker was vitamin B3 which is a green chemical compound. The sorbent provides particles can extract the analytes via interactions such as surface adsorption, occlusion van der waals and π–π interactions. The extraction procedure was done by mixing trichloroacetic acid with the egg sample to remove the sample proteins and then the synthesised sorbent at mg – level was added to the supernatant phase and the mixture was vortexed. After centrifuging, the supernatant phase was removed and sorbent particles containing the extracted analytes were eluted using acetonitrile. After that, this phase containing the analytes was taken and used in the following dispersive liquid – liquid microextraction process that was done to more enrichment the analytes using a deep eutectic solvent. After optimisation of the extraction process, sensitive limits of detection and quantification were found in the ranges of 0.21–0.28 and 0.70–0.93 ng g−1, respectively. Acceptable extraction recoveries of the analytes ranged from 60 to 73%. The method was selective regarding the analytes, as there were no interfering peaks eluted at the retention times of the analytes. After the validation step, the offered method was employed for the determination of the tetracycline antibiotics in various egg samples and the effect of ultraviolet waves in decontaminating them from egg samples was investigated.

Dispersive solid phase extraction of tacrolimus from biological samples using curcumin and iron-based metal organic frameworks nanocomposite followed by LC-MS/MS determination

Tacrolimus is a potent immunosuppressive drug used in the prevention of tissue rejection. It has a narrow therapeutic index. Therefore, the determination of its concentration in biological fluids like plasma and urine is a very crucial issue. In this research, tacrolimus concentrations in plasma and urine samples were determined with a dispersive solid phase extraction procedure coupled to high-performance liquid chromatography-tandem mass spectrometry. For this purpose, a curcumin modified metal-organic framework was synthesized and used in extraction procedure. Tacrolimus was adsorbed onto the sorbent surface with aid of vortexing. Then, the adsorbed tacrolimus was eluted by a suitable solvent. Important parameters in extraction procedure were optimized by “one-variable-at-a-time” approach and reported as below: sorbent amount, 10 mg; sample solution pH, 2; agitation mode, vortexing; adsorption and desorption times, 1 min, and eluent (volume), methanol (200 µL). Under the optimized conditions and according to the International Council for Harmonization guidelines, the validation of the method was performed, and the results showed acceptable accuracy and precision (relative standard deviations ≤14 %), good linearity in a wide range (4–200 ng mL−1), and low limits of detection (1.2 ng mL−1 in plasma and 0.34 ng mL−1 in urine) and quantification (4.7 ng mL−1 in plasma and 1.12 ng mL−1 in urine). Finally, the validated method was successfully applied for the determination of tacrolimus in the plasma samples of the patients.

In-situ formation of the adsorbent based on octadecylamine for the extraction of Ag+ ions from aqueous solutions and its determination by microinjection flame atomic absorption spectrometry.

In this research, a dispersive solid phase extraction procedure based on changing the solubility of octadecylamine with pH was proposed to determine Ag+ ions in different water samples. For this purpose, first, the pH of sample solution containing the analyte was adjusted to 10.5. Then desired volume of the octadecylamine dissolved in acidic solution was injected into the solution. Because of the low solubility of octadecylamine in alkaline solution, a cloudy state was formed. The produced octadecylamine particles acted as a complexing agent for Ag+ ions and adsorbent for the formed complex. The obtained cloudy solution was centrifuged and the sedimented particles were removed and dissolved in a diluted nitric acid solution. It was injected into a flame atomic absorption spectrometry to determine the extracted amounts of the analyte. The effect of important parameters such as the amount of octadecylamine, volume of nitric acid, and centrifugation and vortexing conditions on the extraction efficiency of the procedure was studied and optimized. In optimal conditions, the developed method showed a linear range of 0.50-200 µg L-1. The limits of detection and quantification were 0.18 and 0.50 µg L-1, respectively. Extraction recovery was 93.6%. The relative standard deviations were less than 4%. The effectiveness of the method was investigated by determination of Ag+ ions in water and wastewater samples.

Application of a hybrid large pore mesoporous silica functionalized with β-cyclodextrin as sorbent in dispersive solid-phase extraction. Toward sustainable sample preparation protocols to determine polyphenolic compounds in Arbutus unedo L. fruits by UHPLC-IT-MS/MS

A quick, sensitive and selective analytical reversed-phase method using ultra-high performance liquid chromatography coupled to an ion-trap mass spectrometry detector (UHPLC-IT-MS/MS) was employed for the simultaneous determination of nine phenolic compounds (PCs) in strawberry tree (SBT) berries. The sample treatment included a solid-liquid extraction followed by a dispersive solid-phase extraction (dSPE) procedure using a hybrid large pore mesoporous silica (LP-MS) functionalized with β-cyclodextrin (β-CD) as sorbent material. For this purpose, the initial synthesized LP-MS was modified with β-CD following three different synthetic routes, obtaining three new functionalized materials (denoted LP-MS-β-CD-R1, LP-MS-β-CD-R2 and LP-MS-β-CD-R3). All synthesized materials were comprehensively characterized, showing excellent textural properties, and they were also tested as sorbent materials in the extraction of PCs by comparison of SPE and dSPE procedures. The LP-MS-β-CD-R2 as sorbent material in the dSPE procedure showed the best potential to extract and purify the target PCs, being more effective than the other materials and compared with the SPE procedure. The performance of the proposed dSPE-UHPLC-IT-MS/MS method was validated in terms of selectivity, linearity, LOD, LOQ, trueness, precision, and matrix effect, achieving good analytical method performance and demonstrating its feasibility and practicality for the quantification of PCs in SBT fruits. The analysis of the investigated SBT berries revealed, mainly, high contents of arbutin reaching concentrations up to 5979 µg/g dry weight, followed by catechin (661 µg/g dry weight). Arbutin was, undoubtedly, the major PC determined in all SBT berry samples analyzed, being the most prominent and showing a high concentration compared to that of other polyphenols determined in other red berries.

In-situ formation of a solid adsorbent for the extraction of some metal ions from crude oil before their determination by microflow nebulizer inductively coupled plasma-mass spectrometry

The presence of heavy metals in crude oil can create different problems on the oil processing and devices as well as pollution of the environment. Establishment of sample preparation methods for the extraction of metals from crude oil is the bottleneck of a successful determination method due to high hydrophobicity and complexity of crude oil matrix. In this study, a dispersive solid phase extraction procedure was developed for the simultaneous extraction of sixteen metal ions based on in-situ formation of an adsorbent in the sample solution. For this purpose, a suitable amount of dithiooxamide was dissolved in an organic solvent and was injected into the sample solution. By this action, dithiooxamide was re-precipitated in the sample solution and adsorbed the ions. The solid particles were separated and then the ions were eluted by a few microliters of choline chloride: 5-amino-8-hydroxyquinoline deep eutectic solvent under sonication. The presented method was validated and broad linear ranges (7.56–50000 ng g−1) were obtained for calibration curves with coefficient of determination ≥0.992. Acceptable limits of detection (0.003–2.32 ng g−1) and quantification (0.009–7.56 ng g−1) were achieved. Good precision (relative standard deviation less than or equal to 4.3% for intra and inter-day precisions) and acceptable extraction recoveries (66–91%) were also obtained. Seven crude oil samples were analyzed and ten metal ions were determined successfully. The method was compared with the methods reported in literature and it was found that the data obtained by this method were reliable and accurate.

Development of a rapid and efficient analytical method for trace lead determination: Manganese dioxide nanoflower based dispersive solid-phase extraction

Lead (Pb) is a heavy metal that is highly toxic and a major environmental pollutant. Anthropogenic activities are the main sources of Pb release into the air, water and food, from which humans and other organisms become exposed. In this study, a suitable, rapid, and environmental friendly dispersive solid phase extraction procedure based on manganese dioxide nanoflower (MnO 2 NF-DSPE) was developed for the effective enrichment of Pb coupled with flame atomic absorption spectrometry (FAAS). Under the optimal experimental conditions, limit of detection (LOD), quantification (LOQ) values and enhancement in detection power (EDP) obtained for the MnO 2 NFs-DSPE-FAAS system were calculated as 6.1 µg/L, 20.3 µg/L and 44, respectively. Three different ginger tea samples were used in recovery studies to investigate the applicability/accuracy of the proposed method. Matrix matching calibration strategy was performed in recovery studies and percentage recoveries were calculated between 106 and 122% with low standard deviation values. • Trace level lead was preconcentrated by DSPE prior to FAAS measurement. • MnO 2 nanoflowers were used as adsorbent in the extraction procedure. • LOD and LOQ for ginger tea matrix were 6.09 µg/L and 20.29 µg/L, respectively. • The detection limit for conventional FAAS system was improved by about 43.7 folds. • Recovery results for the prepared ginger tea were found in the range of 106.1–121.5%.

Determination of Multi-pesticides Residues in Jasmine Flower and Its Scented Tea.

For minor crops such as jasmine, the lack of pesticide registration and maximum residue limits are important issues that need to be solved in order to facilitate trading and ensure food safety. Meanwhile, reliable and quick analytical methods for multi-pesticide residues in these commodities are few, but required by various stakeholders. In this study, a method for detecting twenty-five most frequently used pesticides in jasmine flower and its scented tea by multi-plug filtration cleanup and ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated. The cleanup process was optimized and compared with the dispersive solid phase extraction procedure. The method was validated, showing that except for methomyl, recoveries of twenty-five pesticides were 64%-108%, with relative standard deviations (n = 5) of 0.33%-10%. The method was successfully applied to detect pesticide residues in marketed samples. The results showed that some flower and tea samples contained a combination of different pesticide residues.

Layered Double Hydroxide/Graphene Quantum Dots as a New Sorbent for the Dispersive Solid-Phase Microextraction of Selected Benzophenones, Phenols, and Parabens

In this study, the synthesis of a layered double hydroxide (LDH) composite with graphene quantum dots (GQDs) and its utilization for the development of a dispersive solid-phase extraction procedure are described. To this end, a carbonate-free Mg-Al LDH was synthesized. The development of the composite material made feasible the use of GQDs in a sample preparation procedure, while the incorporation of the GQDs in the LDH structure resulted in an 80% increase in extraction efficiency, compared to the bare LDH. As a proof of concept, the composite material was used for the development of an analytical method for the extraction, and preconcentration, of benzophenones, phenols, and parabens in lake water using high-performance liquid chromatography, coupled to a diode array detector. The analytical method exhibits low limits of quantification (0.10-1.33 μg L-1), good recoveries (92-100%), and satisfactory enrichment factors (169-186). Due to the abovementioned merits, the easy synthesis and simple extraction, the developed method can be used for the routine analysis of the target compounds.

H-beta zeolite-based dispersive solid-phase strategy for the multi-residue determination of pesticides

In this work, electrostatic interactions, hydrogen bonding and other interactions between a variety of pesticides and H-beta zeolite are discussed based on thermodynamics (Gibbs free energy, enthalpy, and entropy). Combined with the physical properties of the target compounds (octanol-water partition coefficient and molar volume), the characteristics of the physical adsorption on the synthetic zeolite were analyzed, the results of H-beta zeolite adsorption showed that the adsorption rate had a nonlinear relationship with the physical properties, and the adsorption reaction was dominated by the adsorption on the surface and in the pores of the H-beta zeolite. Based on the principle of zeolite adsorption, the parameters of absorbent amount, adsorption time, sample pH, ion strength, sample volume and desorption solvent were optimized, a vortex-assisted dispersive solid-phase extraction procedure coupled with liquid chromatography-tandem mass spectrometry was developed for the analysis of multiple pesticides in surface water. The sample was adjusted by phosphate buffer or hydrochloric acid to pH 4, then adsorbed by 50 mg of zeolite within 10 min, adding 2% (g/v) sodium chloride to the solution. The absorbent was eluted with a mixture of acetonitrile-methanol containing 0.5% formic acid after separation, then filtered prior to analysis. The optimized vortex-assisted dispersive solid-phase extraction method simultaneously achieved a low adsorbent dosage, a high enrichment factor of 25, rapid pre-concentration for 30 min, a low solvent usage of 2 mL and multi-target simultaneous analysis. Method performance in terms of accuracy, precision, limit of detection, and limit of quantitation was performed to validate the reliability of the procedure. The proposed protocol achieved acceptable accuracy (recoveries between 62% and 107%), and precision (relative standard deviation < 20%). The limit of detection of the method was below 0.1 μg/L, and the limit of quantitation was 0.08 μg/L or 0.2 μg/L. The results indicated that zeolite is a promising adsorbent with high adsorption capacity. It has the advantages of being a fast, simple, green and economical method for determining residual pesticides in water.

Simultaneous quantitation of commonly encountered drugs (lidocaine, orphenadrine, chlorpheniramine and chloroquine) in biological specimens using modified QuEChERS technique

To highlight the importance of simultaneous quantitation of commonly encountered drugs (lidocaine, orphenadrine, chlorpheniramine and chloroquine) in biological specimens (blood, urine, and liver) using GC-MS technique. Introduction: quantitation of drugs is of paramount importance in forensic toxicology. It plays a decisive role in establishing the cause of death by determining the therapeutic, toxic or lethal range of drugs in biological specimens. This presentation will provide an insight into the simultaneous quantitation of drugs in blood, urine, and liver in a short time using the dispersive solid phase extraction method. In recent years, the author's lab has seen an increase in the number of cases with a history of overdose of commonly used therapeutic drugs and wrong injections. To address the high influx of cases and backlog situation, there was a need to quantitate the drugs simultaneously with a short run time. The extraction was performed using the modified QuEChERS method. QuEChERS method for extraction of these drugs from biological specimens has already been developed and validated. The separation was achieved on GC-MS (Agilent-7890A/5975, capillary column DB-5, 15 m × 250 μm × 0.25 μm, split less, run time 14.75 min, scan mode) using helium as carrier gas. Brucine was used as an internal standard. Screening of biological specimens on GC-MS indicated the presence of orphenadrine, lidocaine, chlorpheniramine and chloroquine in three different cases. The Selected Ion Monitoring (SIM) mode was used for the quantitation of these analytes in respective case samples. The quantitated amount of lidocaine in liver in case No.1 was 10.25 mg/kg. The quantitated amounts of chloroquine and chlorpheniramine in liver in case No.2 were 19.93 mg/kg and 0.95 mg/Kg respectively. The quantitated amounts of orphenadrine and chlorpheniramine in blood in case No.3 were 1.35 mg/L and 0.13 mg/L respectively. The quantitated amounts of orphenadrine and chlorpheniramine in urine in case No.3 were 5.51 mg/L and 0.47 mg/L respectively. The current method demonstrated a good linearity range (r2) above 0.985 from 100 to 1000 μg/L. The limit of detection (LOD) and limit of quantitation (LOQ) were 100 μg/L for all the analytes. No interference from the matrices was observed and samples remained stable for 12 hours in the GC-MS ALS. The developed method is robust and reproducible which employed the dispersive solid phase extraction procedure with a recovery above 90% for all the analytes. This method has been successfully used for the quantitation of the above mentioned drugs in routine cases. The goal of this research was to simultaneously analyze orphenadrine, lidocaine, chlorpheniramine and chloroquine in blood, urine, and liver samples using GC-MS technique. This research is highly important in forensic toxicology labs in establishing the therapeutic, toxic and lethal range of these therapeutically used drugs. The current method is quick, easy, cheap and reproducible.

Dispersive solid phase extraction of several pesticides from fruit juices using a hydrophobic metal organic framework prior to HPLC-MS/MS determination

A metal organic framework (MOF)-based dispersive solid phase extraction procedure was introduced using a hydrophobic sorbent for the extraction of multi class pesticides from fruit juice samples prior to their determination by high performance liquid chromatography-tandem mass spectrometry. For this purpose, NH2-UiO-66(Zr) MOF was synthesized by a hydrothermal approach. Then the sorbent was silylated and used in the extraction procedure. The extraction procedure was done by using 7 mg of the sorbent from 5 mL of a sample solution containing the analytes. After that, the extracted analytes were eluted and preconcentrated by vaporizing the elution solvent. The method was linear within the range of 0.29–500 ng mL−1. The limits of detection, intra- and inter-day relative standard deviations, and extraction recoveries were in the ranges of 0.02–0.1 ng mL−1, 2.9–8.8%, 6.8–14.4%, and 74–89%, respectively. Performing the method on the selected samples showed that they were free of the analytes. This method can help to monitor the studied pesticides in juice samples as well as improving the safety of foods.

Development of copper nanoflowers based dispersive solid-phase extraction method for cadmium determination in shalgam juice samples using slotted quartz tube atomic absorption spectrometry

In this work, dispersive solid-phase extraction procedure was developed for trace cadmium determination before flame atomic absorption spectrometry (FAAS) measurement. Copper(II) based nanoflowers were synthesized to utilize as adsorbent for preconcentration of cadmium. The detection power of the spectrometric system was enhanced by placing a slotted quartz tube (SQT) onto the flame burner which increases the residence time of the analyte atoms in the flame region. The analytical performance of the developed system was evaluated with and without SQT equipment and the enhancement in detection power was calculated by the ratio of detection limits of CuNF-DSPE-FAAS (copper nanoflower based dispersive solid phase extraction-flame atomic absorption spectrometry) and FAAS system. Enhancement was determined as 73 and 104.3 times for CuNF-DSPE-FAAS and CuNF-DSPE-SQT-FAAS (CuNF-DSPE-slotted quartz tube-FAAS), respectively. Percent recovery results indicated the applicability of the developed method for the determination of trace cadmium.

Application of magnetic benzamide-coated SiC nanocomposite in effervesces-assisted DSPE combined with DLLME for the extraction of pesticides from fruit juice samples

In the present study, a magnetic benzamide-coated SiC composite was synthesized, characterized, and used in a dispersive solid phase extraction procedure. The designed method was used for the extraction of mostly used pesticides (permethrin, chlorpyrifos, haloxyfop methyl ester, hexaconazole, pretilachlor, diniconazole, tebuconazole, triticonazole, phosalone, and difenoconazole) from fruit juice samples prior to their determination by gas chromatography-mass spectrometry. In this approach, an effervescent tablet was prepared by pressing a mixture of tartaric acid, sodium bicarbonate, and the synthesized sorbent. Then the tablet was released into the sample solution and the produced carbon dioxide bubbles were used for dispersion of the sorbent particles into the solution. After extraction, the sorbent was collected by an external magnet and the supernatant was discarded. The analytes adsorbed onto the sorbent surface were eluted by acetone. After vortexing and centrifugation, the supernatant was drawn and mixed with carbon tetrachloride and the mixture was dispersed into a sodium chloride solution. Under the optimal conditions, linear ranges of the calibration curves were in the range of 0.53–2000 ng mL−1. The detection limits and precision of the method (expressed as relative standard deviation) were in the ranges of 0.02–0.21 ng mL−1 and 3.1–6.4%, respectively. Finally, the method was done on grape, apple, and orange juices and difenoconazole and chlorpyrifos were found in grape juice at the concentrations of 3.9 ± 0.3 and 1.5 ± 0.1 ng mL−1, respectively.

Renewable sorbent dispersive solid phase extraction automated by Lab-In-Syringe using magnetite-functionalized hydrophilic-lipophilic balanced sorbent coupled online to HPLC for determination of surface water contaminants

An automated methodology for magnetic dispersive solid phase microextraction integrating bead injection approach for renewable sorbent introduction is presented for the first time and was successfully applied to the enrichment of water contaminants. For this purpose, a simple procedure was developed for the functionalization of commercial SupelTM-Select HLB (Hydrophilic modified styrene polymer) sorbent beads that allowed embedding magnetite nanoparticles (Fe3O4). The sorbent was then used in a dispersive solid phase extraction procedure that was carried out entirely inside the void of an automatic syringe pump following the flow-batch concept of Lab-In-Syringe including automated renewal of the sorbent for each analysis. Mixing processes, sorbent dispersion, and sorbent recovery were enabled by using a strong magnetic stirring bar, fabricated from a 3D printed polypropylene casing and neodymium magnets, inside the syringe. The final extract was submitted to online coupled liquid chromatography with spectrometric detection. System and methodology were applied to determine mebendazole, bisphenol A, benzyl 4-hydroxybenzoate, diclofenac, and triclosan selected as models from different groups of environmental contaminants of current concern. Experimental parameters including extraction and elution times, composition and volume of eluent, and bead recollection were optimized. Required system elements were produced by 3D printing. Enlarging the sample volume by repeated extraction to enhance the sensitivity of the method was studied. Using double extraction from 3.5 mL, limits of detection ranged from 1.2 μg L−1 to 6.5 μg L−1 with an RSD (n = 6) value less than 7% for all the analytes at 25 μg L−1 level. The method was linear in the range of 5–200 μg L−1 and was successfully implemented for the analysis of surface waters with analyte recoveries ranging from 78.4% to 105.6%.

Zeolite H-Beta as a Dispersive Solid-Phase Extraction Sorbent for the Determination of Eight Neonicotinoid Insecticides Using Ultra-High-Performance Liquid Chromatography—Tandem Mass Spectrometry

In this study, a dispersive solid-phase extraction (DSPE) pretreatment procedure using zeolite H-Beta as a sorbent was exploited for the determination of eight neonicotinoids in bottled water and honey products based on ultra-high-performance liquid chromatography–tandem mass spectrometry analysis. The zeolite H-Beta was demonstrated to be a suitable sorbent for neonicotinoid insecticides, even after 10 recycles of reuse. The method performance was evaluated by the linearity (R2 ≥ 0.998), recovery (71–108%), precision (0.1–7.8%), limit of detection (0.05–0.1 ng/mL) and limit of quantification (0.1–0.2 ng/mL), which suggested excellent stability and high sensitivity with the use of the DSPE procedure. The method was further successfully applied in the test of neonicotinoid insecticides in 34 samples. Zeolite H-Beta shows promise as an efficient and practical material for monitoring neonicotinoid insecticides in bottled water and multiplex honey matrices.

Experimental and density functional theoretical modeling of triazole pesticides extraction by Ti2C nanosheets as a sorbent in dispersive solid phase extraction method before HPLC-MS/MS analysis

In this research, a convenient, fast, and green dispersive solid phase extraction procedure based on Ti2C nanosheets was developed for effectively enrichment of some triazole pesticides prior to high performance liquid chromatography-tandem mass spectrometry. Characterization of the etching sorbent was carried out in details. Adsorption and desorption steps have been optimized in detail to obtain efficient phase separation and reliable analytical results. Under optimized conditions, the presented method exhibited a wide working range (0.52–1000 ng mL−1), low detection limits (0.03–0.30 ng mL−1) and acceptable extraction recoveries (70–75%). The introduced method precision was checked by calculating intra and inter-day relative standard deviations for three different concentrations of triazole pesticides. The matrix effect was investigated by the recovery study. Following validation studies, the presented method was successfully applied to the extraction and determination of the studied triazole pesticides from fruit juice samples. The adsorption mechanism was supported by theoretical studies. The interactions between the studied pesticides and Ti2C nanosheets were investigated with the help of density functional theoretical calculations. The calculations supported the obtained experimental results.

Determination of polycyclic aromatic hydrocarbons in soil, tree leaves, and water samples by magnetic dispersive solid-phase extraction based on β-cyclodextrin functionalized graphene oxide followed by GC-FID

A high-performance sorbent was synthesized and used to extract some polycyclic aromatic hydrocarbons (naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, benzo[a]pyrene) from environmental samples by using magnetic dispersive solid-phase extraction (MdSPE) procedure followed by a gas chromatography-flame ionization detector (GC-FID). The sorbent was synthesized by grafting β-cyclodextrin (β-CD) onto magnetic graphene oxide (MGO) via hexamethylene diisocyanate (HMDI) as a linker. Prepared magnetic sorbent (MGO/HMDI/β-CD) was characterized by Fourier transform infrared spectroscopy (FT-IR), the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), the X-ray diffraction (XRD), vibrating-sample magnetometer (VSM), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy. The variables that affect the performance of the extraction method were investigated in detail and thoroughly optimized using experimental design and response surface methodology. Under the optimum conditions (sorbent amount: 25 mg, extraction time: 20 min, concentration of NaCl: 27% (w/v), desorption time: 6 min, volume of desorption solvent: 300 µL, and desorption solvent: toluene), enrichment factors were obtained between 46 and 62. The results indicated that the extraction recoveries of these compounds were in the range of 73.0–97.1%. Good linearity within the range of 5.0–1000.0 ng/mL with coefficients of determination higher than 0.984 was achieved. Detection limits were found to be 0.1–0.5 ng/mL, while the relative standard deviations (RSDs) were calculated to be ≤ 8.0% (n = 3). The fabricated sorbent was successfully applied for the extraction and quantification of PAHs in pretreated environmental samples (soil, tree leaves, and river water).

Application of Magnetic Nanoparticles Coated with Crosslinked Zwitterionic Poly(ionic liquid)s for the Extraction of Oligonucleotides.

Magnetic nanoparticles coated with zwitterionic poly(ionic liquid)s were applied for dispersive solid-phase extraction of oligonucleotides. The materials were synthesized by miniemulsion copolymerization of ionic liquids and divinylbenzene on magnetic nanoparticles. The functional monomers contain a positively charged imidazolium ring and one of the anionic groups: derivatives of acetate, malonate, or butyl sulfonate ions. Adsorption of unmodified DNA oligonucleotide on obtained materials was possible in ion-exchange (IE) and hydrophilic interactions (HI) mode. The adsorption in IE was possible at low pH and was almost complete. The adsorption in HI mode required the usage of appropriate addition of organic solvent but did not provide full adsorption. Studies on the desorption of the analytes included determining the impact of ammonium acetate concentration and pH and organic solvents addition on the recovery. The material containing acetic fragments as an anionic group was selected for the final procedure with the use of 10 mM ammonium acetate (pH = 9.5)/methanol (50/50, v/v) as an elution solution. The magnetic dispersive solid-phase extraction procedure was tested for the oligonucleotides with various modifications and lengths. Moreover, it was applied to extract DNA oligonucleotide and its synthetic metabolites from enriched human plasma without any pre-purification, with recoveries greater than 80%.

Solvent-loaded metal-organic framework of type MIL-101(Cr)-NH2 for the dispersive solid-phase extraction and UHPLC-MS/MS analysis of herbicides from paddy field waters.

A novel solvent-loaded dispersive solid-phase extraction (SL-DSPE) method integrated with liquid-phase microextraction (LPME) has beendeveloped by the direct loading of solvent into the pores of a metal-organic framework (MOF), MIL-101(Cr)-NH2. Despite numerous advantages of MOFs, they are usually highly hydrophobic which limits their dispersibility and therefore effective contact with the analytes in aqueous samples. To overcome this and promote its interactions with polar compounds, MIL-101(Cr) was functionalized with -NH2 and loaded with a comparatively polar organic solvent, dichloromethane. The purpose of dichloromethane was to condition the MIL-101(Cr)-NH2, promote LPME of the analytes and facilitate the re-collection of the materials after the extraction. Five chlorophenoxy acid herbicides, including 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, 4-chlorophenoxyacetic acid, 2-(2,4-dichlorophenoxy)propionic acid, and 2-(2,4,5-trichlorophenoxy)propionic acid, were studied and determinedby ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). MIL-101(Cr)-NH2 was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and surface area measurement. Several extraction parameters were optimized, and under the most favorable conditions, the SL-DSPE-UHPLC-MS/MS method achieved enrichment factors between 25 and 66. Low limits of detection (2.66-19.7ng·L-1) and wide dynamic working ranges with good linearity (r2 ≥ 0.991) were attained for all analytes. The method was repeatable, with intra- and inter-day relative standard deviations (RSDs) below4.5 and 7.6%, respectively, for three replicate determinations. The application of SL-DSPE-UHPLC-MS/MS to paddy field waters gave satisfactory relative recoveries ranging between 80.2 and 108%, with RSDs better8.4%. Several of the CPAs were detected in these samples. Graphical abstract Schematic of the solvent-loaded dispersive solid-phase extraction procedure. By directly loading dichloromethane into the pores of MIL-101(Cr)-NH2, this method improves the extraction capability of the sorbent through the combination of solvent- and sorbent-based microextraction.