Preparation of alumina-coated magnetite nanoparticle for extraction of trimethoprim from environmental water samples based on mixed hemimicelles solid-phase extraction

In this study, a new type of alumina-coated magnetite nanoparticles (Fe₃O₄/Al₂O₃ NPs) modified by the surfactant sodium dodecyl sulfate (SDS) has been successfully synthesized and applied for extraction of trimethoprim (TMP) from environmental water samples based on mixed hemimicelles solid-phase extraction (MHSPE). The coating of alumina on Fe₃O₄ NPs not only avoids the dissolving of Fe₃O₄ NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS, satisfactory concentration factor and extraction recoveries can be produced with only 0.1 g Fe₃O₄/Al₂O₃ NPs. Main factors affecting the adsolubilization of TMP such as the amount of SDS, pH value, standing time, desorption solvent and maximal extraction volume were optimized. Under the selected conditions, TMP could be quantitatively extracted. The recoveries of TMP by analyzing the four spiked water samples were between 67 and 86%, and the relative standard deviation (RSD) ranged from 2 to 6%. Detection and quantification limits of the proposed method were 0.09 and 0.24 μg L⁻¹, respectively. Concentration factor of 1000 was achieved using this method to extract 500 mL of different environmental water samples. Compared with conventional SPE methods, the advantages of this new Fe₃O₄/Al₂O₃ NPs MHSPE method still include easy preparation and regeneration of sorbents, short times of sample pretreatment, high extraction yields, and high breakthrough volumes. It shows great analytical potential in preconcentration of organic compounds from large volume water samples.     

Pipette‐tip solid‐phase extraction using cetyltrimethylammonium bromide enhanced molybdenum disulfide nanosheets as an efficient adsorbent for the extraction of sulfonamides in environmental water samples

Surfactant cetyltrimethylammonium bromide enhanced molybdenum disulfide was used as an adsorbent in pipette‐tip solid‐phase extraction for the pretreatment of sulfonamides in environmental water samples. The factors affecting the extraction recoveries of the analytes, including the sample pH value, amount of sorbent, type and volume of eluent solution, and salt concentration were optimized. This pipette‐tip solid‐phase extraction method demonstrated good linearity (0.05–10.0 µg/L) with a coefficient of determination of 0.9984–0.9996, limit of detection (0.2–0.4 ng/L) and limit of quantitation (0.5–1.0 ng/L), good analyte recoveries (76–91), and acceptable limit of quantitation (<10%) under the optimized conditions. These results indicated that the proposed method was a good tool for monitoring sulfonamides in environmental water samples.     

Determination of fipronil and its metabolites in environmental water samples by meltblown nonwoven fabric-based solid-phase extraction combined with gas chromatography-electron capture detection

In this study, a new method for the determination of fipronil and its three metabolites in environmental water samples was developed based on meltblown nonwoven fabric solid-phase extraction combined with gas chromatography-electron capture detection. As the core material of medical masks, meltblown nonwoven fabric is made of polypropylene superfine fibers which are randomly distributed and bonded together with a relatively large specific surface area and good permeability. Polypropylene as a high molecular hydrocarbon-based polymer has the characteristics of good hydrophobicity and lipophilicity, which can be applied for the separation and enrichment of hydrophobic substances in food, environment, and biological samples. The meltblown nonwoven fabric is soft and can fill the solid-phase extraction cartridge tightly. This aspect also makes it suitable to be used as an ideal solid-phase extraction sorbent. A series of parameters influencing the extraction efficiency were investigated, and under the optimized conditions, fipronil and its three metabolites had a good linear relationship in the range of 0.2–100 μg/L with a correlation coefficient R^{2 of} more than 0.999. The recoveries at three spiked concentrations were in the range of 99.2–107.3% with the relative standard deviations less than 9.8% (intra-day) and 8.1% (inter-day). The limit of detection for the four target analytes was in the range of 0.02–0.06 μg/L. Finally, this method was successfully applied in the analysis of fipronil and its three metabolites in various types of environmental water samples.     

竹炭为高效吸附剂的固相萃取分析环境水样中的痕量三氯生

建立了一种由竹炭作为固相萃取高效吸附剂富集环境水样中痕量三氯生的新方法. 研究并优化了几个影响富集效率的参数. 在优化条件下, 三氯生的检测限为0.08 μg/L, 在1～100 μg/L 范围内有良好的线性关系, 相对标准偏差为2.9% (n=7). 方法可应用于实际废水样品的分析.     

Fabrication of highly crystalline covalent organic framework for solid-phase extraction of three dyes from food and water samples

Herein, a covalent organic framework, which was fabricated at room temperature by using 1,3,5-tris(p-formylphenyl) benzene and 1,3,5-tris(4-aminophenyl)benzene as building blocks, was employed as an adsorbent for solid-phase extraction of dyes including congo red, methyl blue and direct red 80 for the first time. The prepared covalent organic framework was properly characterized by different techniques and the results revealed that it had a uniform spherical structure, high crystallinity, satisfactory surface area, and good thermal stability. Moreover, the adsorption performance of the material was explored by using static and dynamic adsorption experiments and the results indicated that the material showed good adsorption capacities for three dyes with adsorption capacities in the range of 55.25–284.10 mg/g and the adsorption equilibrium can be achieved in 15 min. Further, to achieve the best adsorption effects of the material, the influence parameters such as pH, ionic strength, type of desorption solvent, and the material dosage in the solid-phase extraction column, were optimized in turn. Finally, under optimal conditions, the solid-phase extraction coupled with HPLC was applied to the analysis of dyes in food and water samples. The recoveries of dyes in actual samples were satisfactory, revealing the unique applicability of the material in the sample pretreatment field.     

Solid ink-printed filter paper as a green adsorbent material for the solid-phase extraction of UV filters from water samples

This work describes the development of a new green solid-phase extraction approach, which is based on the use of low-cost extraction discs composed of plain filter papers that are covered with a synthetic wax-like coating. The filter papers are printed in a commercial solid ink printer, which dispenses a synthetic wax-like ink on the surface of the paper, to cover the hydrophilic cellulose fibre matrix with an interface of lipophilic domains where non-polar analytes can partition through hydrophobic interactions. The modified paper filters were used to extract hydrophobic organic compounds from water samples following the customary procedure of solid-phase extraction without sorbent preconditioning and needless of high-vacuum sources. As a proof-of-concept application, a series of non-polar organic UV filters were used as model analytes to optimise the extraction parameters and evaluate the performance of the method in spiked water samples. Based on this principle, a new sample preparation platform with low environmental footprint has been developed that enables extraction to be carried out using low-cost, environmental benign and non-toxic conventional materials. The advantages and disadvantages of the method, alongside with its future prospects towards the development of custom-made ‘printed extraction kits’, are envisioned and discussed.     

Determination of phenolic compounds in water samples by on-line solid-phase extraction—supercritical-fluid chromatography with diode-array detection

Summary The eleven Environmental Protection Agency (EPA) priority phenolic compounds have been determined by solid-phase extraction (SPE) coupled on-line to supercritical-fluid chromatography (SFC) with diodearray detection. The variables affecting chromatographic separation were optimized and the analytes were separated at 40 °C in two diol columns connected in series; a gradient of methanol, as modifier, and CO₂ was used as mobile phase. Under these conditions, all the compounds studied were separated to baseline in less than 13 min. PLRP-S and LiChrolut EN were tested as sorbents in a 10×3 mm i.d. laboratory-packed precolumn for solid-phase extraction. An ion-pair reagent, tetrabutylammonium bromide (TBA), was used in the extraction process to increase break-through volumes. The performance of the method was checked with tap and river waters and the pre-concentration of 20 mL of sample in a PLRP-S pre-column enabled phenolic compounds to be determined at low μg L⁻¹ levels with limits of detection ranging between 0.4 and 2 μg L⁻¹. The repeatability and reproducibility between days (n=3) for real samples spiked at 10 μg L⁻¹ were lower than 10%.     

磁性氧化石墨烯的制备及其在环境水样中7种内分泌干扰物检测中的应用

制备了十二胺修饰的磁性氧化石墨烯纳米材料并将其用于磁固相萃取。在对磁固相萃取材料合成与萃取条件以及液相色谱分离等条件进行优化的基础上,建立了磁固相萃取与高效液相色谱-紫外检测对环境水样中7种内分泌干扰物的分析方法。该方法对雌酮、雌二醇、雌三醇、双酚A、17α-乙炔基雌二醇、己烷雌酚和雄烯二酮7种内分泌干扰物的检出限在0.10～0.23 nmol/L之间。将该方法分别应用于废水样品和湖水样品的加标回收试验,回收率在73.9%～112.9%和74.9%～114.7%之间。该方法操作简便,分析成本较低,可为环境水体中内分泌干扰物的分析提供技术支持。     

Determination of aromatic amines in environmental water samples using solid-phase extraction modified with sodium dodecyl sulphate and micellar liquid chromatography

Extraction and determination of seven aromatic amines in environmental water samples were performed with solid-phase extraction (SPE) and micellar liquid chromatography (MLC) using experimental design. Extraction of aromatic amines was carried out with a C₁₈ cartridge modified with sodium dodecyl sulphate (SDS). The washing solution and elution solvent for extraction of aromatic amines were aqueous solution containing 5% (v/v) acetonitrile and 5% (v/v) acetone and 3 mL methanol, respectively. The chemometrics approach was applied for the separation optimisation of these compounds using MLC. Different mobile phase compositions were used for modelling based on retention times to obtain the best separation using central composite design. The optimum mobile phase composition for separation and determination of analytes in water samples was 69 mM SDS, 9% v/v 1-propanol and pH = 6.4. Recoveries were between 84.8–93.5% with relative standard deviation (RSD) less than 5.8% (n = 5). Limits of detection and linear range were 1–4.5 and 3.1–125.0 µg/L, respectively. The proposed method was applied to determine the aromatic amines in real samples (river and well waters). Amount of 4-nitroaniline and 3-nitroaniline in river water sample were 2.15 and 1.91 µg/L, respectively.     

对氨基苯亚甲基硫代若丹宁固相萃取分离光度法测定环境水和食品样品中的铅

合成了新试剂对氨基苯亚甲基硫代若丹宁(ABTR),并用红外光谱、核磁共振氢谱和元素分析鉴定其结构。研究了ABTR与铅的显色反应,在pH3.8的HAc NaAc缓冲介质中,吐温80存在下,ABTR与铅反应生成2∶1稳定络合物,该络合物可被WatersSep PakC18小柱固相萃取,小柱上富集的络合物用乙醇洗脱后富集倍数可达50倍,在乙醇介质中,λmax=545nm,体系摩尔吸光系数ε=1.09×105L·mol-1·cm-1。铅量在0.05～4.0μg/mL内符合比尔定律,本法可用于环境水和食品样品中铅的测定。     

Selective solid-phase extraction of tebuconazole in biological and environmental samples using molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) were prepared by precipitation polymerization using tebuconazole (TBZ) as a template. Frontal chromatography and selectivity experiments were used to determine the binding capabilities and binding specificities of different MIPs. The polymer that had the highest binding selectivity and capability was used as the solid-phase extraction (SPE) sorbent for the direct extraction of TBZ from different biological and environmental samples (cabbage, pannage, shrimp, orange juice and tap water). The extraction protocol was optimized and the optimum conditions were: conditioning with 5 mL methanol:acetic acid (9:1), 5 mL methanol and 5 mL water respectively, loading with 5 mL aqueous samples, washing with 1.2 mL acetonitrile (ACN):phosphate buffer (5:5, pH3), and eluting with 3 mL methanol. The MIPs were able to selectively recognize, effectively trap and preconcentrate TBZ over a concentration range of 0.5–15 μmol/L. The intraday and interday RSDs were less than 9.7% and 8.6%, respectively. The limit of quantification was 0.1 μmol/L. Under optimum conditions, the MISPE recoveries of spiked cabbage, pannage, shrimp, orange juice and tap water were 62.3%, 75.8%, 71.6%, 89% and 93.9%, respectively. MISPE gave better HPLC separation efficiencies and higher recoveries than C18 SPE and strong cation exchange (SCX) SPE. Figure HPLC analysis of spiked pannage after MISPE (A) and after C18 SPE (B). HQ (1), E3 (2), p-NP (3), FTF (4), TBZ (5), PNZ (6), HXZ (7) Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Multi-walled carbon nanotubes as a solid-phase extraction adsorbent for the determination of chlorophenols in environmental water samples

Multi-walled carbon nanotubes (MWCNs) are used as adsorbent for solid-phase extraction (SPE) of several chlorophenols (CPs). CPs were adsorbed on MWCNs cartridge, then desorbed with pH 10.0 methanol, finally determined by HPLC. Under the optimized conditions, detection limits of 0.08-0.8 ng mL(-1) were obtained. The method had been applied to analyze the five CPs in tap water and river water.     

Preparation and evaluation of molecularly imprinted ionic liquids polymer as sorbent for on-line solid-phase extraction of chlorsulfuron in environmental water samples

In this report, vinylimidazolium ionic liquid as a functional monomer for preparation of chlorsulfuron (CS) imprinted polymers were first studied. The imprinted materials showed high selectivity for CS, and fast kinetics so that adsorption equilibrium was achieved within 5 min. These materials have been further employed to detect trace CS from water samples by online preconcentration coupled with HPLC. The sorbent offered good linearity (0.005-30 μg L(-1), r(2)>0.99) for on-line solid-phase extraction of trace chlorsulfuron. Under the optimal experimental conditions, the recovery for chlorsulfuron was in the range of 81.0-110.1% for the water samples, with RSDs ranging from 1.2 to 7.6%.     

Preparation of magnetic surface molecularly imprinted polymers for the selective extraction of triazines in environmental water samples

ABSTRACT

In this work, a magnetic molecularly imprinted polymer (Fe₃O₄@SiO₂@MIPs) was prepared via a surface-imprinted method for the determination of the triazines in environmental water samples combined with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer showed that the Fe₃O₄@SiO₂@MIPs was successfully synthesised and exhibited superparamagnetism. The isotherm adsorption, selectivity and adsorption kinetics experiments showed that the Fe₃O₄@SiO₂@MIPs exhibited excellent specific recognition and fast adsorption equilibrium for triazines. The adsorption process is spontaneous and endothermic. The isotherm adsorption was consistent with Scatchard model and adsorption kinetic fit pseudo-second-order kinetic model. Under the optimised adsorption conditions, the Fe₃O₄@SiO₂@MIPs was directly used to selectively enrich six triazines in environmental water samples. The enrichment volume was up to 500 mL, and the matrix effects were down to 0.7–12.4%. The built method has excellent linearities in the range of 0.25–500 ng L^?1 with R² in the range of 0.998–0.999, lower limit of detections (0.02–0.08 ng L^?1) and higher precision (2.4–7.2%). The Fe₃O₄@SiO₂@MIPs is expected to be widely applied to the direct enrichment of triazines in bulk environmental water samples.     

Determination of sulfonamide residues in water samples by in-line solid-phase extraction-capillary electrophoresis

An in-line solid-phase extraction-capillary electrophoresis method with UV–vis detection was developed for the monitoring of residues of five sulfonamides (sulfadoxin, sulfadimethoxine, sulfamerazine, sulfachloropyridazine and sulfamethoxazole) in tap, bottled mineral and river waters. For this purpose an analyte concentrator was constructed, based on the introduction of a small portion of a solid-phase extraction sorbent into the electrophoretic capillary to carry out an in-line concentration step, improving sensitivity. A detailed study was carried out to optimize parameters affecting the in-line solid-phase extraction process, such as the design of the concentrator device, type of sorbent and conditions of elution and injection. The proposed method is simple for the environmental monitoring of these antibiotic residues in waters, allowing the direct injection of the samples without any off-line pretreatment and achieving limits of detection between 0.3 and 0.6 μg/L. Recoveries ranging 52.2–109.2% and relative standard deviations below 13.4% were obtained.     

Selective magnetic solid-phase extraction of amide herbicides from fish samples coupled with ultra-high-performance liquid chromatography with tandem mass spectrometry

An efficient magnetic dummy template molecularly imprinted polymer nanocomposite was prepared using multi-walled carbon nanotubes as a support and metolachlor deschloro as a dummy template. The obtained nanocomposites were characterized using Fourier transform infrared spectroscopy, vibrating sample magnetometry, scanning electron microscopy, and transmission electron microscopy. The adsorption performance of the obtained nanocomposites was evaluated through binding experiments, including static adsorption, kinetic adsorption, and selective recognition studies. The obtained nanocomposites were successfully applied as selective sorbents for the magnetic solid-phase extraction of seven amide herbicides (alachlor, acetochlor, pretilachlor, butachlor, metolachlor, diethatyl ethyl, and dimethachlor) coupled with liquid chromatography-tandem mass spectrometry from fish samples. Under the optimized conditions, the limit of detection was 0.01–0.1 μg/kg. The obtained recoveries of the amide herbicides from the fish samples were in the range of 88.0 to 102.1% with a relative standard deviation of less than 7.5%. This method, which eliminated the effect of template leakage on qualitative and quantitative analysis was found to be superior to the methods reported in the literature. The results indicated that it could be successfully applied to analyze amide herbicides in fish samples with satisfactory recoveries.     

Selective solid-phase extraction of bisphenol A using molecularly imprinted polymers and its application to biological and environmental samples

Molecularly imprinted polymers (MIPs) were prepared using bisphenol A (BPA) as a template by precipitation polymerization. The polymer that had the highest binding selectivity and ability was used as solid-phase extraction (SPE) sorbents for direct extraction of BPA from different biological and environmental samples (human serum, pig urine, tap water and shrimp). The extraction protocol was optimized and the optimum conditions were as follows: conditioning with 5 mL methanol–acetic acid (3:1), 5 mL methanol, 5 mL acetonitrile and 5 mL water, respectively, loading with 5 mL aqueous samples, washing with 1 mL acetonitrile, and eluting with 3 mL methanol. MIPs can selectively recognize, effectively trap and preconcentrate BPA over a concentration range of 2–20 μM. Recoveries ranged from 94.03 to 105.3 %, with a relative standard deviation lower than 7.9 %. Under the optimal condition, molecularly imprinted SPE recoveries of spiked human serum, pig urine, tap water and shrimp were 65.80, 82.32, 76.00 and 75.97 %, respectively, when aqueous samples were applied directly. Compared with C18 SPE, a better baseline, better high-performance liquid chromatography separation efficiency and higher recoveries were achieved after molecularly imprinted SPE.      

Recent applications of atomic spectroscopy coupled with magnetic solid-phase extraction techniques for heavy metal determination in environmental samples: A review

Atomic spectroscopy is the most popular approach to determine the presence of heavy metals in the environment. Heavy metals are potentially toxic and have various negative effects on many living organisms, including humans. With the rapid increase in the variety of industries and human activities, large amounts of heavy metals are released into the atmosphere, water, and soil. Heavy metal analysis of environmental samples is very important for determining the exposure limits. Environmental samples are highly complex matrices, and various sample preparation techniques have been developed for the extraction of heavy metals from them, including magnetic solid-phase extraction (MSPE). The use of MSPE in heavy metal analysis has recently gained significant attention owing to a number of advantages. MSPE technique overcomes main issues such as phase separation, handling, and column packing. The use of magnetic adsorbents in sample preparation has grown over the past few years, making MSPE a promising technique for sample preparation. The objective of this review article is to provide the latest applications of MSPE coupled with atomic spectroscopy for heavy metal determination in environmental samples. In addition, new magnetic adsorbents and their analytical merits are emphasized.     

环境样品中双酚类化合物的固相萃取研究进展

双酚类化合物作为一类内分泌干扰物广泛存在于环境介质中,经过多种途径迁移至人体后,可对人体产生内分泌毒性、细胞毒性、基因毒性、生殖毒性、二噁英毒性和神经毒性,已被加拿大政府风险评估识别为进一步优先控制名录。随着环境领域对双酚类化合物的广泛关注,相关研究工作逐渐向水、沉积物、灰尘和生物样品等多介质开拓。但是,由于不同环境样品在基质复杂性和污染物浓度水平等方面存在显著差异,开发提取效率高、净化选择性好、普适性强、操作简单、高通量的提取和净化方法,有助于实现环境介质中双酚类化合物的高灵敏、批量检测。近年来,新型前处理技术发展迅速,尤其是固相萃取技术,在双酚类化合物提取与净化方面取得了长足的发展,不仅在一定程度上克服了传统提取净化方法存在的耗时、耗力和耗溶剂等不足,而且为新型污染物分析提供了更多的技术支持。该文简述了典型双酚类化合物的理化性质、用途用量和环境危害,重点围绕新型固相萃取吸附剂开发和固相萃取模式转变两个方面,总结了固相萃取在双酚类化合物提取净化方法方面取得的进展。商品化固相萃取产品普适性强,在环境监测领域应用范围较广,适用于双酚类化合物的产品种类有限;新型吸附剂研发聚焦吸附容量(如介孔硅材料、碳纳米材料、金属-有机框架材料、环糊精)和选择性(如分子印迹聚合物和混合模式离子交换聚合物)两个方面,种类多样化可满足不同检测需求;越来越多的高灵敏分析仪器不断推向市场,为适应新的发展形势,固相萃取模式正逐渐向微型化、自动化、简易化等方向发展,如QuEChERS、固相微萃取、磁固相萃取等。     

Magnetic solid-phase extraction based on Fe3O4/graphene oxide nanoparticles for the determination of malachite green and crystal violet in environmental water samples by HPLC

This work describes a magnetic Fe₃O₄/graphene oxide (GO)-based solid-phase extraction (MSPE) technique for high performance liquid chromatography (HPLC) detection of malachite green (MG) and crystal violet (CV) in environmental water samples. Fe₃O₄/ GO magnetic nanoparticles were synthesised by a chemical co-precipitation method and characterised by scanning electron micrograph, transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and surface area analyser. The prepared Fe₃O₄/GO magnetic nanoparticles were used as the adsorbents of MSPE for MG and CV. By coupling with HPLC, a sensitive and cost-effective method for simultaneous determination of MG and CV was developed. The important parameters including the amount of Fe₃O₄/GO, pH of the sample solution, extraction time, salt effect, the type and volume of desorption solvent were investigated in detail. Under optimised conditions, the calibration curves were linear in the concentration range of 0.5–200 μg L^?1, and the limits of detection were 0.091 and 0.12 μg L^?1 for MG and CV, respectively. Finally, the established MSPE-HPLC method was successfully applied to determine MG and CV in environmental water samples with the recoveries ranging from 91.5% to116.7%.