Multifunctionalized magnetic mesoporous silica as an efficient mixed-mode sorbent for extraction of phenoxy carboxylic acid herbicides from water samples followed by liquid chromatography-mass spectrometry in tandem

One-Pot Preparation of Mixed-Mode Reversed-Phase Anion-Exchange Silica Sorbent and its Application in the Detection of Cyclopiazonic Acid in Feeds and Agricultural Products

A novel co-bonded octyl and pyridine silica (OPS) sorbent was prepared and applied for the solid phase extraction (SPE) of cyclopiazonic acid (CPA, a type of mycotoxin) in feed and agricultural products for the first time. A simple mixed-ligand one-pot reaction strategy was employed for OPS sorbent preparation. Nitrogen adsorption-desorption measurements, elemental analysis (EI), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) analysis demonstrated the successful immobilization of octyl and quaternary ammonium groups onto the surface of silica gel. The large specific surface area, high-density functional groups, and mixed-mode anion-exchange characteristics of these silica particles made them the ideal material for the efficient extraction of CPA. Additionally, the OPS sorbents displayed excellent batch-to-batch reproducibility, satisfactory reusability, and low cost. The SPE parameters were optimized to explore the ionic and hydrophobic interactions between CPA and the functional groups, and the ultra-high performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-MS/MS) parameters were optimized to obtain a desirable extraction efficiency and high sensitivity to CPA. Meanwhile, the OPS sorbent presented a satisfactory extraction selectivity and low matrix effect. Under the optimized conditions, our developed CPA detection method was used to determine CPA level in rice, wheat flour, corn flour, peanut, and feed samples, exhibiting a lower detection limit, better linearity, higher sensitivity, and satisfactory extraction recovery rate than previously reported methods. Therefore, our method can be preferentially used as a method for the detection of CPA in agricultural products and feeds.

ZIF-67-modified magnetic nanoparticles for extraction of phenoxy carboxylic acid herbicides

Phenoxy carboxylic acid (PCA) herbicides are commonly used herbicides that can easily accumulate in soil, groundwater, crops, and vegetable surfaces. Thus, they pose a serious risk to human health. Accurate detection of trace amounts of PCAs in various matrixes is crucial. Herein, ZIF-67-modified magnetic nanoparticles (MNPs, ZIF-67@Fe3O4) were prepared by growing ZIF-67 on the surface of Fe3O4 MNPs. The introduction of ZIF-67 improved the dispersion of Fe3O4 nanoparticles in water and enhanced their extraction performance for PCAs. When an eluent consisting of ammonia water and acetonitrile (5% : 95%; v/v) was employed, 10 mg of ZIF-67@Fe3O4 displayed optimal extraction performance for PCAs in a 20 mL sample solution at a pH of 3. We achieved a limit of detection ranging from 0.014 μg L-1 to 0.056 μg L-1 for four types of PCA herbicides by using the newly developed method. Notably, the values were considerably lower than the maximum concentration levels of PCAs in drinking water set by the Environmental Protection Agency. The relative recovery rate of PCAs using ZIF-67@Fe3O4 ranged from 83.75% to 117.07% when applied to river water and apple samples. These results demonstrate the great potential of ZIF-67@Fe3O4 in determining the residues of organic pesticides in real samples.

Facile fabrication of naphthalene-functionalized magnetic nanoparticles for efficient extraction of polycyclic aromatic hydrocarbons from environmental water and fish samples

In this study, naphthalene-modified magnetic nanoparticles (Fe3O4@Nap) were simply prepared based on specific chelation interaction between phosphate groups and metal ions on Fe3O4 surface. The resultant Fe3O4@Nap were characterized by FTIR, BET, SEM, TEM, NAM, TGA, and VSM techniques. With Fe3O4@Nap as adsorbent, the polycyclic aromatic hydrocarbons (PAHs) were efficiently extracted by magnetic solid-phase extraction (MSPE) from environmental water and fish samples through the π-π interaction between modified naphthalene groups and PAHs, followed by their determination by GC-MS/MS. The key parameters influencing the extraction efficiency were investigated. Under the optimized conditions, the Fe3O4@Nap-based MSPE/GC-MS/MS method proposed in this paper was evaluated and applied for analyzing PAHs in environmental water and fish samples. And the proposed MSPE/GC-MS/MS method exhibited good linearities for water samples (in the range of 0.1-10 ng/mL, R2 >0.9945) and for fish samples (in the range of 1-100 ng/g, R2 > 0.9905). The limits of detection (LODs) for water and fish samples were 0.004-0.031 ng/mL and 0.07-0.28 ng/g, respectively. Additionally, this method exhibited desirable accuracy and precision. The PAH recovery values from water and fish samples ranged from 81.5% to 109.6% with inter- and intra-day relative standard deviations (RSDs) of less than 12.8%. The MSPE/GC-MS/MS method was successfully applied to the analysis of real environmental water and fish samples. Overall, the newly synthesized Fe3O4@Nap exhibited high sensitivity, specificity, reusability, repeatability, and it could efficiently extract PAHs from environmental water and fish samples by MSPE.

Determination of trace phenoxy carboxylic acid herbicides in environmental water samples by covalent organic frameworks based solid phase extraction coupled with liquid chromatography-tandem mass spectrometry

The determination of traces levels of pesticide residue in water is crucial for monitoring water quality. In this study, covalent organic frameworks (COFs), namely TAPA-TFPB-COFs were prepared at room temperature (25 °C) and applied as adsorbents for the solid phase extraction (SPE) of phenoxy carboxylic acid herbicides (PCAs). The extraction was followed by analyzation using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under the optimal conditions, ultrasensitive and specific analysis of PCAs in water samples was achieved. The method exhibited high sensitivity with low limits of detection (0.08-0.28 ng L^-1), good linearity in the range of 1.00 to 200 ng L^-1 and satisfactory repeatability (intra-day: 3.72-5.30%; inter-day: 2.02-4.04%). The method was successfully applied to the analyzation of trace PCAs in tap, well, and river water and the spiked recoveries were in the range of 81.1-112%. These results indicate that the SPE-LC-MS/MS technique with TAPA-TFPB-COFs as the SPE adsorbent is a promising technique for the detection of trace levels of PCAs in environmental water samples.

Development of sol-gel silica-based mixed-mode zwitterionic sorbents for determining drugs in environmental water samples

Four novel mixed-mode zwitterionic silica-based functionalized with strong moieties sorbents were synthesized and evaluated through solid-phase extraction (SPE) to determine acidic and basic drugs in environmental water samples. All sorbents had the same functionalization: quaternary amine and sulfonic groups and C₁₈ chains so that hydrophobic and strong cationic exchange (SCX) and strong anionic exchange (SAX) interactions could be exploited, in addition, two of them had carbon microparticles embedded. All sorbents retained both acidic and basic compounds in the preliminary assays but only the basic compounds were retained selectively through ionic exchange interactions when a clean-up step was introduced. The SPE method was therefore optimized to promote the selective retention of the basic compounds, initially with the two best-performing sorbents. After optimization of the SPE protocol, these sorbents were evaluated for the analysis of environmental water samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method with the best-performing sorbent was then validated with 100 mL of river samples and 50 mL of effluent wastewater samples in terms of apparent recoveries (%R_app) spiking samples at 50 ng/L (river) and 200 ng/L (river and effluent), matrix effect, linear range, method quantification and detection limits, repeatability, and reproducibility. It should be highlighted that %R_app ranged from 40 to 85% and matrix effects ranged from -17 to -4% for spiked river samples. When the method was applied to river and effluent wastewater samples, most compounds were found in the range from 24 to 1233 ng/L with detection limits from 1 to 5 ng/L.

Recent advances of ordered mesoporous silica materials for solid-phase extraction

This review mainly focuses on the development and application of ordered mesoporous silica materials for solid-phase extraction in recent years. It overviews not only bare mesoporous silica but also the functionalized mesoporous silica with organic groups, molecularly imprinted polymers, and magnetic materials. These mesoporous silica materials were used as the extraction adsorbents in cartridge solid-phase extraction, dispersive solid-phase extraction, magnetic solid-phase extraction, micro-solid-phase extraction and matrix solid phase dispersion. Coupled with atomic emission spectrometry, chromatography or other detection methods, these techniques efficiently extracted and sensitively determined various targets, such as metal ions, perfluorocarboxylic acids, pesticides, drugs, endocrine disruptors, phenols, flavanones, polycyclic aromatic hydrocarbons, parabens and so on. Based on unique advantages of mesoporous silica materials, the developed analytical method successfully analyzed different matrix samples, like environmental water samples, soil samples, food samples, biological samples and cosmetics. In addition, the prospects of these materials in solid-phase extraction are presented, which can offer an outlook for the further development and applications.

Automation in quantifying phenoxy herbicides and bentazon in surface water and groundwater using novel solid phase extraction and liquid chromatography tandem mass spectrometry

The occurrence of phenoxy herbicides is a financial and regulatory concern for drinking water treatment plants. This paper presents a new method of quantification for nine phenoxy-acids and bentazon in different water samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). The method is based on an automated solid phase extraction (SPE) process that applied hydrophilic modified polystyrene and divinylbenzene cartridges at low pH (<2.0). Main advantages of the presented method include the reduced consumption of organic solvent in extraction and the fully automated sample pre-concentration. The method is thus more environmentally-friendly. In the quantification step, five stable isotopically labelled analogues were used as internal standards to account for the losses during sample preparation and to calibrate the ion source response under the mass spectrometric detection. The method was optimized in terms of sample preparation and subsequent LC-MS/MS separation to obtain reliable measurement of the analyte concentration during real sample analysis. The method quantification limit was between 1.5 and 10.0 ng/L for target compounds in surface water and groundwater samples. The method was validated at three fortification levels between 10.0 and 1000 ng/L, and the results showed fit-for-purpose recovery with appropriate precision at low concentration levels. The method was also utilized to analyse thirty-two actual water samples from different sources. Forty percent of the analysed samples contained detectable level of herbicides, ranging from 1.91 to 40.5 ng/L. The concentrations of targeted herbicides in our study were comparable to those found in water samples in other regions of world.

Adsorptive remediation of environmental pollutants using magnetic hybrid materials as platform adsorbents

Effective separation and remediation of environmentally hazardous pollutants are burning areas of research because of a constant increase in environmental pollution problems. An extensive number of emerging contaminants in the environmental matrices result in serious health consequences in animals, humans, and plants, even at trace levels. Therefore, it is of paramount significance to quantify these undesirable pollutants, even at a very low concentration, from the natural environment. Magnetic solid-phase extraction (MSPE) has recently achieved huge attention because of its strong magnetic domain and easy separation through an external magnetic field compared with simple solid-phase extraction. Therefore, MSPE appeared the most promising technique for removing and pre-concentration of emerging pollutants at trace level. Compared to the normal solid-phase extraction, MSPE as magnetic hybrid adsorbents offers the unique advantages of distinct nanomaterials and magnetic hybrid materials. It can exhibit efficient dispersion and rapid recycling when applying to a very complex matrix. This review highlights the possible environmental applications of magnetic hybrid nanoscale materials as effective MSPE sorbents to remediate a diverse range of environmentally toxic pollutants. We believe this study tends to evoke a variety of research thrust that may lead to novel remediation approaches in the forthcoming years.

[Determination of seven phenoxy acid herbicides in water by dispersive solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on cationic metal-organic framework mixed matrix membrane]

离子型金属有机骨架材料(iMOFs)对离子型化合物具有良好的选择吸附性,利用水热法合成了一种金属有机骨架材料MIL-101-NH₂,以聚偏二氟乙烯(PVDF)为交联剂将其制备成混合基质膜(MMM),然后用三氟甲烷磺酸甲酯进行季胺基功能化改性,最终得到阳离子型金属有机骨架膜材料MIL-101-$NMe_{3}^{+}$-PVDF MMM,采用分散固相萃取方式富集水中的苯氧羧酸类除草剂,建立了一种基于阳离子型MOF混合基质膜的分散固相萃取-超高效液相色谱-串联质谱(UPLC-MS/MS)测定水体中7种苯氧羧酸类除草剂的分析方法。通过傅里叶变换红外光谱和扫描电子显微镜对制备的混合基质膜进行表征,结果表明季胺基功能化改性是成功的,得到了阳离子型MOF膜。对影响萃取效果的主要因素(吸附剂用量、水样pH值、萃取时间、洗脱剂种类、洗脱剂体积及洗脱时间)进行了优化,确定了最佳萃取条件。以0.01%(v/v)甲酸水溶液和乙腈作为流动相进行梯度洗脱,目标化合物在ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)上分离,在电喷雾电离源、负离子模式下进行多反应监测(MRM),外标法定量。结果表明,7种苯氧羧酸类除草剂在各自范围内线性关系良好,线性相关系数均大于0.997,方法的检出限(LOD)和定量限(LOQ)分别为0.00010~0.00090 μg/L和0.00033~0.00300 μg/L。在0.005、0.05和0.2 μg/L 3个加标水平下进行加标回收率试验,7种待测物的平均回收率为80%~102%,日内、日间相对标准偏差分别为1.4%~9.4%和4.2%~12.6%。该方法操作简单、快速,灵敏度高,适用于环境水体中7种苯氧羧酸类除草剂的检测。