Commercial polymeric fiber as sorbent for solid-phase microextraction combined with high-performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons in water

Synthesis of an ordered macroporous metal-organic framework for efficient solid-phase extraction of aflatoxins from milk products

Aflatoxins (AFs) exhibit hepatotoxicity, immunotoxicity, and carcinogenicity, and their detection in food has attracted widespread concern. An ordered macroporous metal-organic framework (OM-ZIF-8) based on solid-phase extraction (SPE) was used to extract six AFs from milk products. The SPE conditions, including eluting solvent, eluting volume, amounts of OM-ZIF-8, pH of loading solution, loading solvent, ionic strength, loading flow rate, and elution flow rate, were exhaustively optimized. Under optimal parameters, the six AFs were detected by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The OM-ZIF-8 exhibited satisfactory AFs extraction performance through ordered macropore structure, π-π interaction, coordination interaction, and electrostatic interaction. Furthermore, linearity in the range of 0.01-100 ng mL-1 with low detection limits of 0.002-0.0150 ng mL-1 was obtained, and the relative recoveries of AFs were 80.3-110 % with relative standard deviation ≤8.7 %. Thus, this research provides a promising platform for the analysis of trace AFs in complex foods.

Graphene oxide modified magnetic polyamidoamide dendrimers based magnetic solid phase extraction for sensitive measurement of polycyclic aromatic hydrocarbons

In this study, graphene oxide modified magnetic polyamidoamine dendrimers (MNPs@PAMAM-G2.0@GO) nanoparticles were successfully prepared by amidation method. The obtained MNPs@PAMAM-G2.0@GO nanocomposites were examined by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM) and transmission electron microscopy (TEM), etc. MNPs@PAMAM-G2.0@GO exhibited excellent adsorption property and was investigated for magnetic solid phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) from water. The detection of extracted PAHs was accomplished by high performance liquid chromatography (HPLC) and gas chromatography tandem mass spectrometry (GC-MS/MS). The target PAHs included anthracene (ANT), pyrene (PYR), fluoranthene (FLT), carbazole (CB), 7-methylquinoline (7-MQL), 9-methylcarbazole (9-MCB), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DBT). Important operation parameters for MSPE that could affect the extraction efficiencies of PAHs were investigated in detail. Under optimal parameters, the constructed method demonstrated excellent linear range with 0.001-10 μg L^-1 for analytes and low limits of detection within the range of 0.11-0.9 ng L^-1. The spiked average recoveries of PAHs in natural water samples ranged from 92.5% to 105.2%. The promising results indicated that MNPs@PAMAM-G2.0@GO could be employed to efficiently extract PAHs from aqueous samples.

Construction of a magnetic covalent organic framework for magnetic solid-phase extraction of AFM1 and AFM2 in milk prior to quantification by LC-MS/MS

A magnetic covalent organic framework (M-COF) was designed and selected as sorbent for magnetic solid-phase extraction (MSPE) of AFM1 and AFM2 in milk, followed by LC-MS/MS analysis. The application of 2,5-Dihydroxy-1,4-benzenedicarboxaldehyde (Dt) and 4',5'-bis(4-aminophenyl)-[1,1':2',1″-terphenyl]-4,4″-diamine (BAPTPDA) as monomers endows M-COF excellent properties for adsorbing AFM1 and AFM2. The morphology, structure, stability, and magnetism of the Fe₃O₄@COF(BAPTPDA-Dt) were characterized by various techniques including scanning electron microscopy, transmission electron microscopy, FTIR, thermogravimetric analysis, and vibrating sample magnetometer. The Fe₃O₄ microspheres were covered by COF shells. Fe₃O₄@COF exhibited excellent magnetism and stability. Some parameters that may influence the adsorption efficiency of MSPE were also optimized, making the extraction process more effective, time-saving (about 3 min), and less organic-reagent-consuming (only 4 mL of acetonitrile required). It is noteworthy that the Fe₃O₄@COF(BAPTPDA-Dt) can be reutilized more than 8 times. The AFM1 and AFM2 were determined by LC-MS/MS. The LODs for AFM1 and AFM2 were in the range 0.0069 to 0.0078 μg kg^-1. A wide linearity range (0.01-100 μg kg^-1) with coefficients of determination (R²) ranging from 0.9998 to 0.9999 was obtained. The recoveries at four spiked concentrations (0.05, 0.5, 5, and 50 μg kg^-1) in the milk matrix ranged from 85.2 to 106.5%. The intraday RSDs and the interday RSDs were in the range 1.74-4.58% and 2.65-6.69%, respectively. The matrix effect (9.3% for AFM1 and 6.7% for AFM2) was also significantly lower than that observed in other work . Overall, the established method has provided a powerful tool for rapid pretreatment and sensitive determination of AFM1 and AFM2 in milk with negligible matrix effect, presenting important value in toxicant determination.

Self-Assembled Three-Dimensional Microporous rGO/PNT/Fe3O4 Hydrogel Sorbent for Magnetic Preconcentration of Multi-Residue Insecticides

The purpose of this work was to develop a highly selective, sensitive, and reliable method for multi-residual analysis. A three-dimensional microporous reduced graphene oxide/polypyrrole nanotube/magnetite hydrogel (3D-rGOPFH) composite was synthesized and utilized as a magnetic solid-phase extraction (MSPE) sorbent to preconcentrate thirteen insecticides, including five organophosphorus (isocarbophos, quinalphos, phorate, chlorpyrifos, and phosalone), two carbamates (pirimor and carbaryl), two triazoles (myclobutanil and diniconazole), two pyrethroids (lambda-cyhalothrin and bifenthrin), and two organochlorines (2, 4′-DDT and mirex), from vegetables, followed by gas chromatography-tandem mass spectrometry. This method exhibited several major advantages, including simultaneous enrichment of different types of insecticides, no matrix effect, high sensitivity, and ease of operation. This is ascribed to the beneficial effects of 3D-rGOPFH, including the large specific surface (237 m2 g−1), multiple adsorption interactions (hydrogen bonding, electrostatic, π–π stacking and hydrophobic interaction force), appropriate pore size distribution (1–10 nm), and the good paramagnetic property. Under the optimal conditions, the analytical figures of merit were obtained as: linear dynamic range of 0.1–100 ng g−1 with determination coefficients of 0.9975–0.9998; limit of detections of 0.006–0.03 ng g−1; and the intra-day and inter-day relative standard deviations were 2.8–7.1% and 3.5–8.8%, respectively. Recoveries were within the range of 79.2 to 109.4% for tomato, cucumber, and pakchoi samples at the fortification levels of 5, 25, and 50 ng g−1. This effective and robust method can be applied for determining multi-classes of insecticide residues in vegetables.

Monolithic mixed matrix membrane based on polyethersulfone/functionalized MWCNTs nanocomposite as an SPME fiber: Application to extract chlorophenols from human urine and serum samples followed by GC-ECD

A monolithic mixed matrix membrane of functionalized multi-walled carbon nanotubes-polyethersulfone (MWCNT/PES) was prepared in a non-covalent approach and employed as an SPME fiber for extraction of chlorophenols (CPs). The proposed extraction method was followed by GC-ECD to determine the analytes. The influencing factors on the extraction efficiency such as pH, ionic strength, extraction and desorption temperature and time were studied. Under the selected conditions, calibration curves were linear over a wide concentration range from 0.005 to 1000 µgL^-1 (r² > 0.9961) for target analytes. In addition, the limits of detection (LOD) of the method were obtained in the range of 0.3-30 ng L^-1. The relative standard deviation (RSD) for single fiber repeatability (n = 5) is from 1.4 to 4.6%. Fiber-to-fiber repeatability (n = 3) was also evaluated and the RSD is in the range of 1.3-6.3%. Applications of proposed fiber for extraction of CPs from the headspace of urine and serum samples were successfully investigated. The relative recovery in the biological samples spiked with different levels of CPs were in the range of 91.6-102.5%.

Magnetic metal organic framework for pre-concentration of ampicillin from cow milk samples

The aim of this study is a present of a simple solvothermal synthesis approach to preparation of Cu-based magnetic metal organic framework (MMOF) and subsequently its application as sorbent for ultrasound assisted magnetic solid phase extraction (UAMSPE) of ampicillin (AMP) from cow milk samples prior to high performance liquid chromatography-Ultraviolet (HPLC-UV) determination. Characteristics of prepared MMOF were fully investigated by different techniques which showed the exclusive properties of proposed sorbent in terms of proper functionality, desirable magnetic property and also high specific surface area. Different influential factors on extraction recovery including sorbent dosage, ultrasonic time, washing solvent volume and eluent solvent volume were assessed using central composite design (CCD) based response surface methodology (RSM) as an operative and powerful optimization tool. This is the first report for determination of AMP using MMOF. The proposed method addressed some drawbacks of other methods and sorbents for determination of AMP. The presented method decreases the extraction time (4 min) and also enhances adsorption capacity (250 mg/g). Moreover, the magnetic property of presented sorbent (15 emu/g) accelerates the extraction process which does not need filtration, centrifuge and precipitation procedures. Under the optimized conditions, the proposed method is applicable for linear range of 1.0–5000.0 μg/L with detection limit of 0.29 μg/L, satisfactory recoveries (≥95.0%) and acceptable repeatability (RSD less than 4.0%). The present study indicates highly promising perspectives of MMOF for highly effective analysis of AMP in complicated matrices.

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MMOF was prepared and used for the first time for determination of ampicillin from cow milk samples.

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The extraction method was convenient, rapid and the MMOF can be used more than 8 times.

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The MMOF have high specific surface area (300.0 m²/g) and high adsorption capacity (250.5 mg g⁻¹).

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The separation time was only 5 min, which was much shorter than other reported.

Determination of polycyclic aromatic hydrocarbons (PAHs) in drinking water of Samsun and it's surrounding areas, Turkey

BACKGROUND

Polycyclic aromatic hydrocarbons (PAH) are considered to be one of the major contaminants of drinking water and natural water bodies. Some of the well documented polycyclic aromatic hydrocarbons that are water pollutants and were considered for analysis in this study included benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), benzo[g,h,i]perylene (BgP), and indeno[1,2,3-c,d]pyrene (InD). This study aimed at determining the levels of concentrations of basically five polycyclic aromatic hydrocarbons in 57 drinking water bodies located around Samsun, Ordu, Giresun, Çorum, Amasya, Kastamonu and Sinop provinces.

MATERIALS AND METHOD

In this study, the Environmental Protection Agency (EPA) method 550.1 for the determination of polycyclic aromatic hydrocarbons in drinking by Liquid-Solid Extraction (LSE) and High Performance Liquid Chromatography (HPLC) with Coupled Ultraviolet (CD) and Fluorescence Detection (FD) was used. Sampling procedures were done according to the validated method specified by the Turkish Ministry of Enivironment and Forestry. Prior to the determination of concentrations by HPLC, PAHs contained in the samples were separated from the solid phase by Solid-Phase Extraction (SPE). All data analyses were conducted using SPSS and Excel.

RESULTS

Obtained results from the investigation revealed that the average total PAH and benzo[a]pyrene (BaP) concentration levels in drinking water samples taken from the central districts of Samsun were 2.73 ± 1.51 and 0.35 ± 0.24 ng/L respectively. In drinking water samples taken from Ordu, Giresun, Çorum, Amasya, Kastamonu and Sinop, the average total PAH concentrations were found to be 5.85 ± 3.82 ng/L, 3.79 ± 1.27 ng/L, 1.08 ± 0.62 ng/L, 2.42 ± 1.04 ng/L; 1.92 ± 0.35 ng/L and 4.07 ± 2.33 ng/L respectively. The average (BaP) concentrations for the same named locations were determined as 0.97 ± 0.75 ng/L; 0.55 ± 0.29 ng/L; 0.11 ± 0.08 ng/L; 0.35 ± 0.10 ng/L; 0.14 ± 0.04 ng/L; 0.39 ± 0.23 ng/L, respectively. It is therefore evident that the values ​​of PAH and BaP in drinking water were below the limits of 100 and 10 ng/L ​​specified in the Regulation on Water Intended for Human Consumption. These values are below the set limits proposed by Turkish legislation and WHO.

CONCLUSION

All the results for drinking water, usable water and natural spring water were below the values ​​specified in the Regulation on Water Intended for Human Consumption and WHO. The PAH content of the studied river waters as well were below the limits proposed by Turkish legislation and WHO.

In Situ Miniaturised Solid Phase Extraction (m-SPE) for Organic Pollutants in Seawater Samples

Solid phase extraction (SPE) is a consolidated technique for determining pollutants in seawater samples. The current tendency is to miniaturise systems that extract and determine pollutants in the environment, reducing the use of organic solvents, while maintaining the quality in the extraction and preconcentration. On the other hand, there is a need to develop new extraction systems that can be fitted to in situ continual monitoring buoys, especially for the marine environment. This work has developed a first model of a low-pressure micro-SPE (m-SPE) for persistent organic pollutants (POPs) that can be simply applied to in situ monitoring in the marine environment. This system reduces the volumes of sample and solvents required in the laboratory in comparison with conventional SPE. In the future, it could be used in automated or robotic systems in marine technologies such as marine gliders and oceanographic buoys. This system has been optimised and validated to determine polycyclic aromatic hydrocarbons (PAH) in seawater samples, but it could also be applied to other kinds of persistent organic pollutants (POPs) and emerging pollutants.

Development of a new sorptive extraction method based on simultaneous direct and headspace sampling modes for the screening of polycyclic aromatic hydrocarbons in water samples

A new straightforward and inexpensive sample screening method for both EPA and EU priority polycyclic aromatic hydrocarbons (PAHs) in water has been developed. The method is based on combined direct immersion and headspace (DIHS) sorptive extraction, using low-cost disposable material, coupled to ultraperformance liquid chromatography with fluorescence and UV detection (UPLC-FD-UV). Extraction parameters, such as the sampling mode, extraction time and ionic strength were investigated in detail and optimized. Under optimized conditions, water samples (16 mL) were concentrated in silicone disks by headspace (HS) and direct immersion (DI) modes simultaneously, at room temperature for 9h for the majority of the 24 studied compounds. Ultrasound-assisted desorption of extracted analytes in acetonitrile was carried out also at room temperature. The optimized chromatographic method provided a good linearity (R≥0.9991) and a broad linear range for all studied PAHs. The proposed analytical procedure exhibited a good precision level with relative standard deviations below 15% for all analytes. Quantification limits between 0.7 and 2.3 µg L(-1) and 0.16 and 3.90 ng L(-1) were obtained for compounds analyzed by UV (acenaphtylene, cyclopenta[c,d]pyrene and benzo[j]fluoranthene) and fluorescence, respectively. Finally, the proposed method was applied to the determination of PAHs in different real tap, river and wastewater samples.

A novel microextractor stick (polyaniline/zinc film/stainless steel) for polycyclic aromatic hydrocarbons in water

A novel microextractor stick (MES) has been developed for the determination of trace amounts of polycyclic aromatic hydrocarbons (PAHs) in water samples. The proposed MES was prepared by electrodepositing a Zn-film onto a stainless steel stick followed by a coating with polyaniline (PANI) sorptive layers. This PANI/Zn-film/stainless steel stick produced a large surface area, provided a high extraction efficiency (82.0 ± 6.2% to 111.0 ± 7.5% recovery) of spiked chrysene (Chry) and benzo(a)pyrene (BaP). This MES is cost-effective, easy to prepare, robust and provides a good stick-to-stick reproducibility (n = 10) with a relative standard deviation of less than 10%. The effect of various parameters on the efficiency of extraction of PAHs were optimized, including the extraction time, extraction and desorption stirring speeds, volume of desorption solvent and desorption time. Under the optimum conditions, the limit of detection (S/N ≥ 3) and limit of quantification (S/N ≥ 10) of both Chry and BaP were 0.05 and 0.12 μg L(-1), respectively. The developed MES was successfully applied to determine PAHs in real water samples.

Rapid determination of polycyclic aromatic hydrocarbons in rainwater by liquid-liquid microextraction and LC with core-shell particles column and fluorescence detection

Liquid-liquid microextraction coupled to LC with fluorescence detection for the determination of Environmental Protection Agency's 16 priority pollutant polycyclic aromatic hydrocarbons in rainwater has been developed. The optimization of the extraction method has involved several parameters, including the comparison between an ultrasonic bath and a magnetic stirrer as extractant apparatus, the choice of the extractant solvent, and the optimization of the extraction time. Liquid-liquid microextraction gave good results in terms of recoveries (from 73.6 to 102.8% in rainwater) and repeatability, with a very simple procedure and low solvent consumption. The reported chromatographic method uses a Core-Shell technology column, with particle size <3 μm instead of classical 5-μm particles column. The resulting backpressure was below 300 bar, allowing the use of a conventional HPLC system rather than the more expensive ultrahigh performance LC (UHPLC). An average decrease of 59% in run time and 75% in eluent consumption has been obtained, compared to classical HPLC methods, keeping good separation, sensitivity, and repeatability. The proposed conditions were successfully applied to the determinations of polycyclic aromatic hydrocarbons in genuine rainwater samples.

Evaluation of low-cost disposable polymeric materials for sorptive extraction of organic pollutants in water samples

The capabilities of four commercially available and low cost polymeric materials for the extraction of polar and non-polar contaminants (logK(ow)=-0.07-6.88, from caffeine to octocrylene, respectively) from water samples was compared. Tested sorbents were polyethersulphone, polypropylene and Kevlar, compared to polydimethylsiloxane as reference material. Parameters that affect the extraction process such as pH and ionic strength of the sample, extraction time and desorption conditions were thoroughly investigated. A set of experimental partition coefficients (K(pw)), at two different experimental conditions, was estimated for the best suited materials and compared with the theoretical octanol-water (K(ow)) partition coefficients of the analytes. Polyethersulphone displayed the largest extraction yields for both polar and non-polar analytes, with higher K(pw) and lower matrix effects than polydimethylsiloxane and polypropylene. Thus, a sorptive microextraction method, followed by large volume injection (LVI) gas chromatography-tandem mass spectrometry (GC-MS/MS), was proposed using the former sorbent (2 mg) for the simultaneous determination of model compounds in water samples. Good linearity (>0.99) was obtained for most of the analytes, except in the case of 4-nonylphenol (0.9466). Precision (n=4) at 50 and 500 ng L(-1) levels was in the 2-24% and limits of detection (LODs) were in the 0.6-25 ng L(-1) range for all the analytes studied.

Development of multiwalled carbon nanotubes based micro-solid-phase extraction for the determination of trace levels of sixteen polycyclic aromatic hydrocarbons in environmental water samples

Micro-solid-phase extraction (μ-SPE) was developed for the determination of trace level of 16 United States Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) in river water samples with gas chromatography-mass spectrometry (GC-MS). In the μ-SPE device, multiwalled carbon nanotubes was employed as sorbent and was packed inside an porous polypropylene membrane "envelope" whose edges were heat-sealed to secure the contents. The μ-SPE device was placed in a stirred sample solution to extract the analytes. The porous polypropylene membrane envelope in μ-SPE device acts as a filter to exclude potential interferences, such as eliminating or reducing the influence of particles that are bigger than the pore size. After extraction, analyte desorption was carried out with a suitable organic solvent under ultrasonication. Important extraction parameters were optimized in detail, including the selection and amount of sorbent materials, the extraction temperature and extraction time, desorption solvent and desorption time, amount of organic modifier, agitation speed and sample ionic strength. Under the developed extraction conditions, the proposed method provided good linearity in the range of 0.1-50 μg/L, low limits of detection (4.2-46.5 ng/L), and good repeatability of the extractions (relative standard deviations, <12%, n=5). The developed μ-SPE method was successfully applied to the extraction of PAHs in river water samples. The μ-SPE method was demonstrated to be a fast and efficient method for the determination of PAHs from environmental water samples.