Solid-phase Extraction Adsorbent Research Articles

Highly efficient enrichment of eugenol anesthetics in aquatic products using magnetic nanospheres decorated covalent organic framework microflowers

Herein, uniform magnetic covalent organic framework (MCOF) microflowers were synthesized by facile inlaying aldehyde-functionalized Fe3O4 nanoparticles onto the COF under mechanical stirring at room temperature. The MCOF microflowers kept flower-shaped morphology with high crystallinity and magnetism. In addition, the good water dispersibility and reusability made the MCOF microflowers to be good magnetic solid phase extraction (MSPE) adsorbents for the high-efficiency enrichment of eugenol anesthetics from aquatic products. The MCOF microflowers showed fast adsorption rate (10 min) and high extraction efficiency (above 84.02%) for eugenol anesthetics under optimal conditions. The MCOF microflowers displayed maximum adsorption capacities of 6.67, 12.31, and 16.78 µg g−1 for eugenol, eugenol acetate, and methyl isoeugenol, respectively. The MCOF microflowers based MSPE coupled with high-performance liquid chromatography method was proposed for enrichment and analysis of eugenol anesthetics in tilapia, shrimp and crab samples. The method showed a wide linear of 5.0–500.0 µg kg−1 and low detection limits of 2.4–3.6 μg kg−1 for eugenol anesthetics. The recoveries of spiked eugenol anesthetics ranged from 80.0% to 118.8% with relative standard deviations no>9.2%. Results indicate the high potential of MCOF microflowers to be an adsorbent for efficient extraction and analysis of eugenol anesthetics from complex aquatic product samples.

One-pot preparation of magnetic molecularly imprinted adsorbent with dual template molecules for simultaneously specific capture of sulfonamides and quinolones in water and milk samples

Specific capture is a beneficial tactic in simultaneous monitoring of sulfonamides (SAs) and quinolones (QLs). For this purpose, a new magnetic molecularly imprinted adsorbent based on double-template molecules (DT-MIP@MNA) was facilely prepared by “one-pot” hydrothermal technique and utilized as the adsorbent of magnetic solid-phase extraction (MSPE). Molecular simulation technique was employed to quickly screen functional monomer. The recognition factors of prepared adsorbent towards templates sulfamethazine and nalidixic acid were 5.89 and 2.90, respectively, and the corresponding adsorption capacities were as high as 8.85 mg/g and 8.97 mg/g, respectively. Under the optimized parameters, the proposed DT-MIP@MNA/MSPE was combined with HPLC to simultaneously and selectively monitor trace SAs and QLs residuals in water and milk samples. The achieved limits of detection were 0.012–0.028 μg/L and 0.015–0.032 μg/kg for water and milk samples, respectively. The current supplied a sensitive, reliable and anti-interference method for simultaneously monitoring trace SAs and QLs in food.

Biochar/sodium alginate mixed matrix membrane as adsorbent for in-syringe solid-phase extraction towards trace nitroimidazoles in water samples prior to ultra-high-performance liquid chromatography-tandem mass spectrometry analysis.

In the present work, the herb (Poria cocos (Schw.) Wolf) residue, as an environmentally friendly and renewable biomass source, was converted into novel biochar. Biochar/sodium alginate mixed matrix membrane was fabricated. On this basis, a biochar/sodium alginate mixed matrix membrane-based in-syringe solid-phase extraction was developed combined with ultra-high performance liquid chromatography-tandem mass spectrometry to determine nitroimidazoles in water samples. The factors including times of exaction, type, and volume of elution solvent, and sample solution pH were thoroughly optimized. Then the correlation coefficient was 0.9995-0.9997. The limit of detection of four analytes was between 0.006 and 0.014ng/mL, and the recovery was between 79.02% and 99.1%. Consequently, the established method would provide a new perspective on monitoring nitroimidazoles in water samples.

Progress in the application of novel nano-materials to the safety analysis of agricultural products

The quality and safety of agricultural products are strongly related to human livelihood. Thus, the government and consumers have recently paid increased attention to the quality and safety of agricultural products. The development of efficient, rapid, and sensitive analytical methods for detecting pesticides, veterinary drugs, heavy metals, mycotoxins, and environmental pollutants in agricultural products is of great significance. Owing to the complexity of many sample matrices and the low concentration of pollutants in a typical sample, appropriate sample pretreatment steps are necessary to enrich pollutants in agricultural products. Solid-phase extraction (SPE) is the most widely used sample pretreatment technology; in this technique, the adsorbent generally determines the selectivity and efficiency of the extraction process. An increasing number of novel materials have been used as SPE adsorbents. The extraction efficiency, extraction selectivity, and analytical throughput of SPE could be greatly improved by combining these novel materials with various extraction modes (e. g., solid-phase microextraction, dispersed SPE, and magnetic SPE (MSPE)) during sample preparation. Because of their large specific surface area and high affinity toward target analytes, nanomaterials are often used as SPE adsorbents, thereby greatly improving the selectivity and sensitivity of the analytical technology. More importantly, these materials have become a priority area of research on preconcentration technologies for trace compounds in agricultural products. This paper summarizes the adsorption characteristics of several new nanomaterials, including magnetic materials, carbon-based materials, metal nanomaterials (MNs), metal oxide nanomaterials (MONs), metal organic frameworks (MOFs), and covalent organic frameworks (COFs). These nanomaterials present numerous advantages, such as large specific surface areas, high adsorption capacities, and tailorable structural designs. MSPE employs magnetic materials as sorbents to afford fast dispersion and efficient recycling when applied to complex sample matrices under an external magnetic field. The use of MSPE can avoid several typical problems associated with SPE such as poor adsorbent packing and high pressure, thereby greatly simplifying the pretreatment process and providing a high flux for sample analysis. Carbon-based materials are powdered or bulk nonmetallic solid materials with carbon as the main component; carbon and nitrogen materials, mesoporous carbon, carbon nanotubes, and graphene are some examples of these materials. These materials provide large specific surface areas, abundant pore structures, good thermal stability, high mechanical strength and adsorption capacity, and controllable morphology. Pure and modified carbon nanomaterials have been successfully used to purify target analytes from agricultural products. Given their unique physical and chemical properties, MNs and MONs have attracted significant interest for use in sample preparation. MNs and MONs with excellent thermal and mechanical stabilities show good resistance to a wide pH range and diverse organic solvents, which is crucial in adsorbent-based extraction methods. The surface of these materials can be easily modified with various ligands to improve their selectivity. MOFs and COFs present many advantages such as large specific surface areas, high porosity, adjustable pore performance, and good thermal stability. Several methods that employ novel adsorbent materials to analyze pollutants in a variety of agricultural products, such as chromatography, spectroscopy, mass spectrometry, and other detection technologies, have been established. This paper also reviews the application of adsorbent materials in the analysis of agricultural product quality and safety, and discusses the future development trends of these sorbents in sample preparation for the safety analysis of agricultural products.

BaTiO3 is a novel adsorbent for solid-phase extraction of copper at trace levels in food and water samples before HR-CS-FAAS detection

A simple, precise, and rapid method for preconcentration and determination of copper in food and water samples, based on sonication/vortex-free solid phase extraction with high resolution-continuum source flame atomic absorption spectrometry has been developed. In this study, BaTiO3 was synthesized using a single-step hydrothermal method and used as an adsorbent. BaTiO3 was characterized by FT-IR, SEM-EDX, STEM, XRD, and BET methods. The significant feature of the adsorbent is its high surface-to-volume ratio (177.4 m²/g). Important parameters (pH, adsorbent amount, eluent type and volume, adsorption and desorption time, model solution volume, and matrix effects) were optimized. The linear working range (5 – 250 µg L-1) and the detection limit (1.6 µg L-1) were calculated. The presented method was validated with certified reference material and the addition-recovery tests. The application of the method was evaluated for the extraction and determination of Cu(II) in selected food and water samples and quantitative data were obtained.

Synthesis of Nanomagnetite/Crosslinked Carboxymethyl kappa Carrageenan Nickel Imprinted Composite

Nickel(II) ions are carcinogenic water pollutants. To increase the accuracy of instrumental analysis of Ni(II) content, several analytical preparation methods have been developed, including solid phase adsorption extraction. The development of magnetic solid phase extraction adsorbents for metal ions is required, to support the application of magnetic solid phase adsorption as a method of separating metal ions in aqueous samples. This research describes the synthesis of Magnetic Solid Phase Extraction adsorbents as Ni(II) ion adsorbents, nano magnetite/carboxymethyl kappa-carrageenan (CMKC) crosslinked bisphenol A diglycidyl ether (BADGE) imprinted Ni(II)-IIP ion composites. This research was carried out in several stages, synthesis and characterization of nano magnetite (NM), synthesis and characterization of CMKC, and synthesis of NM/CMKCNi(II)-IIP adsorbents. The results of the synthesis were analyzed for morphological characteristics, magnetic strength, spectral characteristics, crystallinity, and composition using SEM, FTIR, XRD, and XRF instruments. The adsorption ability of Ni(II) of the adsorbent was tested. Determination of Ni(II) ion content in the sample before and after adsorption was carried out using a flame atomic absorption spectrophotometer (FAAS). Based on the results of spectral character analysis, crystal diffraction patterns, magnetic strength, and morphology, it is confirmed that nano-magnetite has been successfully synthesized. The diameter of the nano magnetite grains is 21.8 nm, the adsorbent NM/CMKCNi(II)-IIP has magnetic properties and wavy surface morphology. The optimum adsorption ability of Ni(II) for the NM/CMKCNi(II)-IIP composite was 2.44 mg Ni(II)/g adsorbent. To evaluate the tendency of the adsorption ability of the adsorbent towards Ni(II) ions in the presence of competitor ions, the adsorption ability of the adsorbent to adsorp Ni(II) ions in samples containing Ni(II) ions, Pb(II) ions and a mixture of Ni(II) ions. and Pb(II) were determined, based on the results of the analysis, the ability of the adsorbent to adsorb Ni(II) ions was higher than the ability of the adsorbent to adsorb Pb(II) ions, in all types of samples.

Slice-layer COFs-aerogel: a regenerative dispersive solid-phase extraction adsorbent for determination of ultra-trace quinolone antibiotics.

A novel type of three-dimensional network structure, covalent organic frameworks (COFs) aerogel, was fabricated and applied to dispersive solid-phase extraction (dSPE) of quinolone antibiotics (QAs). Density functional theory (DFT) was applied to investigate the possible interaction mechanism and results confirmed that the strong adsorption affinity is attributed to the intralayer hydrogen bonds and π-π interaction. Furthermore, a sensitive analytical method based on COFs-aerogel for determining quinolone antibiotics residues in water and honey samples was developed and HPLC-MS/MS was used for sample detection and quantification. Under the optimal conditions, COFs-aerogel exhibited a wide linearity (0.1-500 ng∙L-1), low limits of detection (0.02-0.06 ng∙L-1), and good precision (RSD ˂ 10%) for selected QAs. A preliminary practical application of the developed method was proved by the efficient detection of quinolone antibiotics in water and food samples with good recoveries (68.2-104% and 64.0-100% for water and honey samples, respectively). Combining the experimental data with theoretical calculation, results illustrated that COFs-aerogel holds a great potential to capture contaminants and address environmental and food safety issues.

A Carboxyl Group-Functionalized Ionic Liquid Hybrid Adsorbent for Solid-Phase Extraction and Determination of Trace Diclofenac Sodium in Milk Samples.

A simple and efficient sample pretreatment technology is very important for the accurate determination of trace drug residues in foods to ensure food safety. Herein, we report a new carboxyl group-functionalized ionic liquid hybrid solid- phase adsorbent (PS-IL-COOH) for the highly efficient extraction and quantitative determination of diclofenac sodium (DS) residue in milk samples. It was found that the adsorption efficiency of PS-IL-COOH for the ppb level of DS was greater than 93.0%, the adsorption capacity was 934.1 mg/g, and the enrichment factor was 620.0, which surpass most of the previously reported values for DS adsorbents. The high concentration of salts did not interfere with the adsorption of DS. Importantly, the recovery of DS was above 90% after 16 adsorption--regeneration cycles. The synergistic effect of the multiple interactions was found to be the main factor for the high efficiency of DS adsorption. The proposed method was applied to the extraction and detection of DS in milk samples, with the relative recovery ranging from 88.2 to 103.0%.

A stable core-shell metal-organic framework@covalent organic framework composite as solid-phase extraction adsorbent for selective enrichment and determination of flavonoids

Hydrophobization and stability is crucial for the practical application of most metal-organic frameworks (MOFs) in extraction technique. In this study, a stable core-shell MOF@COF composite (NH2-MIL-101(Fe)@TAPB-FPBA-COF) was successfully prepared by Schiff base reaction and applied to solid-phase extraction (SPE) of hydrophobic flavonoids. Notably, the TAPB-FPBA-COF shell acts as a hydrophobic "shield", which not only improves the hydrophobicity and stability of hydrophilic NH2-MIL-101(Fe), but also makes the extraction efficiency of flavonoids from MOF@COF composite significantly higher than that of pure NH2-MIL-101(Fe) and TAPB-FPBA-COF. In addition, a sensitive analytical method with excellent linearities (0.1–500 ng mL−1, R2 ≥ 0.9967), low limits of detection (0.02–0.04 ng mL−1 for water; 0.04–0.07 ng mL−1 for grape juice; 0.06–0.08 ng mL−1 for honey), good repeatability (intra-day/inter-day precision are 1.86–5.37%/1.82–7.79%, respectively) and only 5 mg of adsorbent per cartridge was established by optimizing the SPE process combined with high performance liquid chromatography with ultraviolet-visible detector (HPLC-UV). Meanwhile, selectivity study and comparative experiments with the commercial C18 adsorbent showed that the MOF@COF adsorbent exhibited satisfactory extraction efficiency for flavonoids due to multiple interactions such as hydrogen bonding, hydrophobic, and π-π interactions. Finally, the good recoveries in grape juice (84.5–102.5%) and honey (87.5–104.6%) samples further validated the applicability of the proposed method in complex samples.

Synthesis and application of quaternary amine-functionalized core-shell-shell magnetic polymers for determination of metabolites of benzene, toluene and xylene in human urine samples and study of exposure assessment

As production processes have evolved, airborne concentrations of benzene, toluene and xylene in many workplaces are already well below the occupational exposure limits. However, studies have shown that low levels of exposure to benzene, toluene and xylene can still cause health effects in people exposed occupationally. However, there is no literature on health risk assessment of internal exposure. In view of this, an analytical method based on quaternary amine-functionalized core-shell-shell magnetic polymers (QA-CSS-MPs) was developed for the determination of seven metabolites in urine by MSPE-UPLC-DAD-HRMS. Furthermore, an improved QuEChERS method for the extraction of seven metabolites from human urine samples was introduced for the first time and satisfactory extraction rates were achieved. In addition, QA-CSS-MPs microspheres with core-shell-shell structure were designed and synthesized, and the morphology, composition and magnetic properties of the materials were fully characterized to verify the rationality of the synthetic route. Subsequently, QA-CSS-MPs microspheres were used as magnetic solid-phase extraction (MSPE) adsorbents for the purification of urine extracts, and UPLC-DAD-HRMS was used for the detection of seven metabolites. As a result, this method allows the accurate determination of seven metabolites in urine samples over an ultra-wide concentration range (0.001–100 mg/L). Under optimal experimental conditions, i.e., 2% hydrochloric acid in urine for the hydrolysis and 20 mg of QA-CSS-MPs for 5 min purification, the spiked recoveries of the seven target metabolites ranged from 81.5% to 117.7% with RSDs of 1.0%–9.4%. The limits of detection (LODs, S/N≥3) for the established method were in the range of 0.2–0.3 μg/L. The developed method was applied to 254 human urine samples for the determination of seven metabolites. The results showed that the concentration distributions of three xylene metabolites in urine, 2-MHA, 3-MHA, 4-MHA and total MHA, showed statistically significant differences for occupational exposure (p<0.001). In addition, the results of the internal exposure assessment showed that there is a high potential health risk associated with occupational exposure processes.

Multivariate covalent organic frameworks guided carboxyl functionalized magnetic adsorbent for enrichment of fluoroquinolones in milk prior to high performance liquid chromatographic analysis

Herein, we prepared a carboxyl functionalized magnetic covalent organic framework (Fe3O4@iCOF-COOH) by combining multivariate synthetic strategy with post-synthetic modification. It was used as an adsorbent for magnetic solid phase extraction (MSPE) of six fluoroquinolones (FQs), and showed good absorption performance at neutral pH. Carboxyl groups are found to be crucial for the adsorption of fluoroquinolones. The adsorption mechanism was primarily attributed to strong hydrogen bonding, π-π interaction as well as potential hydrophobic effect. The optimal extraction conditions are sample pH at 6.0, adsorbent dosage of 3 mg, eluent of 1.0 mL methanol solution containing 7.5% ammonia, and extraction/desorption time of 30 min. Under the optimized conditions, the Fe3O4@iCOF-COOH was used as an adsorbent for MSPE of FQs in milk, an analytical method was established by combining with high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The limits of detection (LODs) and limit of quantification (LOQs) were 1.24–4.58 ng⋅mL−1 and 4.12–15.3 ng⋅mL−1, respectively. The recoveries of target FQs in spiked milk were 68.4–105%. This work provides a new way to prepare covalent organic framework based adsorbents for solid phase extraction, and can be readily extended to other type of adsorbents.

A novel doped metal–organic skeleton MnDUT-52 as a sorbent for dispersive solid phase extraction of diphenyl ether herbicides in the water environment

A manganese doped metal–organic framework composite (MnDUT-52) was fabricated by a facile solvothermal method and applied as an adsorbent for dispersive solid phase extraction (DSPE) of trace diphenyl ether herbicides (Des) in water samples. The doped material exhibited large surface area (527.3 m2/g) and a higher zeta potential (43.2 mV) compared with its precursor (8.57 mV). And the quantitative parameters affecting the DSPE process (i.e., adsorbent amount, adsorption time, pH, ionic strength, desorption solvent and desorption volume) were optimized in detail. Under the optimal conditions, MnDUT-52 exhibited good reusability (6 times reuse, RSDs ≤ 5.8 %). Notably, the conjugation, hydrophobic and electrostatic interactions contributed to the good adsorption of Des by MnDUT-52. Finally, a method coupled with high-performance liquid chromatography-ultraviolet (HPLC-UV) was developed. It provided wide linear range (0.2–300 ng/mL), low detection limits (0.06–0.10 ng/mL) and extraction recovery (82.4–102.5 %). The developed method was successfully applied for the fast and sensitive determination of Des in water samples.

Calix[4]arene-based covalent organic frameworks with host-guest recognition for selective adsorption of six per- and polyfluoroalkyl substances in food followed by UHPLC-MS/MS detection

Long-term ingestion or exposure to food contaminated with per- and polyfluoroalkyl substances (PFASs) may cause potential harm to human health. Due to the low contents of PFASs in complex food matrices, it is of great significance to develop adsorbents with excellent properties to enrich PFASs before analysis. Herein, calix[4]arene (CX4) was used as building block to prepare ordered crystalline covalent organic frameworks (COFs). The perfect combination of the host-guest recognition ability of CX4 and the porosity of COFs makes the CX4-COFs selective and high adsorption capacity for linear molecular PFASs (261–1055 mg/g). The adsorption behavior and mechanism were verified by isotherm adsorption experiments and simulation calculations. The CX4-COFs were then used as adsorbents for membrane solid-phase extraction (M-SPE), combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) to determine PFASs in food. The method has low detection limits (0.11–0.28 ng/kg) and good precision (1.3%−9.8%), and has been successfully applied to the simultaneous enrichment and determination of six PFASs in fish, shrimp and shellfish. Satisfactory recoveries (79.9%−118%) were obtained. This study provides a new strategy for preparing CX4-COFs containing macrocyclic molecules with different morphologies and expands the application of COFs as attractive enrichment media for sample pretreatment.

Ultrasound-assisted dispersive solid-phase extraction for the preconcentration of dyes in water samples

In this research, the magnesium ferrite/zinc oxide (MgFe2O4/ZnO) nanocomposite has been utilized as an effective adsorbent in the ultrasound-assisted dispersive solid-phase extraction (USA-DSPE) coupled to a spectrophotometric method for preconcentration of methylene blue (MB) and safranin O (SO) dyes. X-Ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) analyses were performed to characterize and confirm the properties of the synthesized MgFe2O4/ZnO nanocomposite. Box-Behnken design (BBD) based on response surface methodology (RSM) was utilized to optimize the variables. The results of this research showed that the maximum extraction efficiency was obtained at pH = 7, eluent volume of 140 µL, adsorbent amount of 1.53 mg, and ultrasonic time of 8 min. After optimization by RSM and using the Quadratic model, the extraction efficiency for MB and SO was 98.60% and 97.23%, respectively. The analysis of variance (ANOVA) showed that the data obtained from the experiment were consistent with the predicted model. Under optimal conditions, the calibration curve was linear in the range of 5–1000 µg/L (coefficient of determination of 0.9884) for MB and 10–1100 µg/L (coefficient of determination of 0.9973) for SO. The limit of detections (LOD) of the proposed method for MB and SO were determined as 1.5 µg/L and 3 µg/L, respectively. The relative standard deviations (RSD, n = 5) for MB and SO were obtained as 1.1% and 2.1%, respectively. The results of adsorbent recovery revealed that MgFe2O4/ZnO nanocomposite could be used several times without a significant adsorbent efficiency loss. Furthermore, the findings of interference studies revealed that the presence of different ions does not cause substantial interference with the extraction of dyes. The environmental water samples analysis showed that the extraction efficiency for dyes was in the range of 93.74–99.11%.

Preparation of COF-coated nickel foam adsorbents for dispersive solid-phase extraction of 16 polycyclic aromatic hydrocarbons from Chinese herbal medicines

Covalent organic framework coated nickel foam (NF@COF) was prepared as a sorbent for the dispersive solid phase extraction (DSPE) of polycyclic aromatic hydrocarbons (PAHs) from Chinese herbal medicines (CHMs) prior to their determination by gas chromatography-mass spectrometry (GC-MS). The structure and morphology of the as-synthesized NF@COF were characterized by different techniques. Various key parameters affecting the performance of the DSPE method, including the amount of sorbent, desorption solvent, desorption volume and time, extraction time, and sample volume, were investigated. Under the optimized conditions, NF@COF combined with GC-MS was successfully applied to the determination of 16 PAHs in CHMs. The method showed wide linearity (20–2000 ng mL−1), low limits of determination (0.3–2.7 ng mL−1), and high recoveries (78.0–124%). These results revealed that NF@COF has the potential for efficient extraction of PAHs from complex samples.

Carboxyl-based deep eutectic solvent modified magnetic graphene oxide as a novel adsorbent for fast enrichment and extraction of estrogens in milk prior to HPLC-UV analysis

In this study, a magnetic graphene oxide modified with green carboxyl-based deep eutectic solvent (MGO@DES) was synthesized for the first time and employed as a highly efficient adsorbent for the magnetic solid-phase extraction (MSPE) of three estrogens in milk samples. With large specific surface, good hydrophobicity and abundant adsorption sites, MGO@DES exhibited excellent extraction performance for estrogens. The adsorption kinetic experiment revealed that 5 mg of MGO@DES reached the equilibrium of estrogen adsorption within 3 min. MGO@DES based MSPE coupled with HPLC-UV method was developed and applied to the determination of three estrogens in milk samples. Good linearity (R2 > 0.9953) was obtained in the range of 1–200 ng mL−1 and the low limits of detection were 0.20–0.28 ng mL−1. The spiked recoveries were in the range of 90.3–105.7%, with RSDs less than 7.9%.

Magnetic chitosan-zeolite composite as an adsorbent in ultrasound-assisted magnetic solid phase extraction of tetracyclines in water samples

An ultrasound-assisted magnetic solid-phase extraction method was developed to pre-concentrate tetracyclines (TCs) in wastewater and river water. The magnetic chitosan-zeolite composite was used as an adsorbent. The morphological and structural properties of the adsorbent were characterised by various analytical techniques. The factors affecting the ultrasound-assisted magnetic solid-phase extraction method were optimised using a central composite design. A high performance liquid chromatography equipped with a photodiode array detector was used to quantify TCs in wastewater and river water samples. Under optimised parameters, the developed analytical approach gave acceptable linearity (LOQ-400 µg L−1) with correlation coefficients exceeding 0.993, while the detection and quantitation limits ranged from 0.05–0.67 and 0.14–2.03 µg L−1, respectively. Attained recoveries were 90–101%, with intraday and interday precision expressed as the relative standard deviation (%RSD) below 5%. Even though the target analytes (tetracycline, oxytetracycline and oxytetracycline) were not detected in environmental samples, the synthesised adsorbent was suitable for the isolation of TCs in a complex matrix resulting in an accurate, precise, rapid and sensitive analytical method.

The Influence of Foreign Ions on Determination and Speciation of Cr(VI) and Cr(III) from Water Samples

This study reports: a) the content of Ca, Cd, Co, Cr(III), Cr(VI), Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn in wastewater from metal industries and rivers that flow near the metal processing industries; b) the possibility of quantitative determination of Cr(III) and Cr(VI) in the presence of the following cations: Fe3+, Cu2+, Ca2+, Mg2+, Ni2+, Mn2+; and Zn2+ and anions Cl-, NO3-, and SO42-; c) speciation of Cr(III) and Cr(VI) on silica gel modified with Nb2O5 . Metals were determined by flame atomic absorption spectrometry, except for Na and K, which were determined by atomic emission spectrometry, and Cr(VI) by ultraviolet-visible spectrophotometry. When the concentration of cations is higher than Mg2+ (&gt;25 mg/L), Ni2+ (&gt;100 mg/L), Fe3+ (&gt;250 mg/L), Zn2+ (&gt;500 mg/L), and Mn2+ (&gt;1000 mg/L), an error greater than 10 % is obtained in the measurement of Cr(III) . Silica gel modified with Nb2O5 can be considered as an effective solid phase extraction adsorbent for speciation of Cr species and simultaneous concentration of Cr(III). The proposed method was successfully applied to the speciation and determination of Cr(III) and Cr(VI) in the analyzed samples. The content of almost all analyzed metals has been below the permitted values for wastewaters.

Application of Diphenyl Functionalization of Nickel Foam as Dispersive Solid-Phase Extraction Adsorbent to Polycyclic Aromatic Hydrocarbon Contaminants in Chinese Herbal Medicines

Application of Diphenyl Functionalization of Nickel Foam as Dispersive Solid-Phase Extraction Adsorbent to Polycyclic Aromatic Hydrocarbon Contaminants in Chinese Herbal Medicines

Separation and purification of glycosides from medicinal plants based on strong polar separation medium with online closed-loop mode

Natural glycosides widely distributed in medicinal plants are valuable sources of therapeutic agents, showing various pharmacological effects. The separation and purification of natural glycosides are meaningful for their pharmacological research, which face with great challenges due to the complex of medicinal plants samples. In this work, two kinds of functional monolithic separation mediums A and S were fabricated and fully applied in the online extraction, separation and purification of active glycoside components from medicinal plants with a simple-procedure closed-loop mode. Chrysophanol glucoside and physcion glucoside were detected and separated from Rhei Radix et Rhizoma using separation medium A as a solid-phase extraction adsorbent. Rhapontin was isolated and purified from Rheum hotaoense C. Y. Cheng et Kao using separation medium S as the stationary phase of high-performance liquid chromatography. Compared to the reported literatures, high yield of 5.68, 1.20 and 4.76 mg g−1 of these three products were obtained with high purity. These two online closed-loop mode methods were carried out using high-performance liquid chromatography system, in which the sample injection, isolation and purification procedures are all online mode, and reduced loss compared to offline extraction and purification procedures, thus achieving high recovery and high purity.