Magnetic solid phase extraction of mefenamic acid from biological samples based on the formation of mixed hemimicelle aggregates on Fe(3)O(4) nanoparticles prior to its HPLC-UV detection

Dispersive Magnetic Solid-Phase Extraction as a Novelty Sample Treatment for the Determination of the Main Aflatoxins in Paprika

Dispersive magnetic solid-phase extraction (DMSPE) technique is proposed as a new sensitive and effective sample treatment method for the determination of aflatoxins in paprika samples. DMSPE was followed by ultrahigh-performance liquid chromatography and high-resolution mass spectrometry detection (UHPLC-HRMS) using a non-targeted acquisition mode for the detection of main aflatoxins (aflatoxin G1, G2, B1 and B2) and derivatives. DMSPE was based on the use of magnetic nanocomposite coated with polypyrrole (PPy) polymer and the main experimental parameters influencing the extraction efficiency in adsorption and desorption steps have been studied and optimized. Analyses were performed using 250 µL magnetic PPy nanocomposite into the sample solution, adsorbing the analytes in 30 min and desorbing them with ethyl acetate (2 mL) in 15 min. The method has been validated, obtaining quantification limits between 3.5 and 4.7 µg kg-1 and recoveries between 89.5-97.7%. The high recovery rate, wide detection range and the use for the first time of the reusable Fe3O4@PPy nanomaterial in suspension for solid food matrices, guarantee the usefulness of the method developed for adequate control of aflatoxins levels in paprika. The proposed methodology was applied for the analysis of 31 samples (conventional and organic) revealing the absence of aflatoxins in the samples.

Development of magnetic dispersive micro-solid phase extraction based on magnetic agarose nanoparticles and deep eutectic solvents for the isolation and pre-concentration of three flavonoids in edible natural samples

In the present study, an environmentally friendly magnetic dispersive micro-solid phase extraction was developed based on magnetic agarose nanoparticles and deep eutectic solvents for the isolation and pre-concentration of three flavonoids (morin, quercetin, and kaempferol) from dark tea, chocolate, vegetable, and fruit juice samples. In this method, deep eutectic solvents were synthesized from less toxic and low-cost substances under feasible conditions and used as eluents in the desorption process. These solvents can be considered as a green alternative to traditional organic reagents to increase the adsorption capacity and reduce the matrix interferences, dangerous waste generation and environmental pollution. A Plackett-Burman design was employed for screening the experimental variables. The effective variables were then optimized by Box-Behnken design (BBD). Under the optimial conditions, the presented method demonstrated wide linear ranges of 1-500 μg. L^-1 for morin and quercetin, and 5-500 μg. L^-1 for kaempferol with satisfactory recoveries above 91%. Limit of detections (LODs) and quantifications (LOQs) of flavonoids varied in 0.2-1.1 μg. L^-1 and 0.66-3.63 μg. L^-1, respectively. The precision of the proposed method was the range of 2.6-5.7%.

Preconcentration and Detection of Gefitinib Anti-Cancer Drug Traces from Water and Human Plasma Samples by Means of Magnetic Nanoparticles

Along of widespread application of anti-cancer drug Gefitinib (GEF), it appears in human body fluids as well as clinical wastewater. Consequently, a reliable and easy-to-adapt detection technique is of essential importance to quantify the drug in different media. The extraction and quantitative detection of anti-cancer drug Gefinitib (GEF) is demonstrated based on a straightforward and efficient magnetic nanoparticle-assisted preconcentration route from water and human plasma samples. Iron oxide magnetic nanoparticles (Fe₃O₄) have been prepared with an average particle size of 15 nm and utilized as extractible adsorbents for the magnetic solid-phase extraction (MSPE) of GEF in aqueous media. The method is based on MSPE and preconcentration of GEF followed by High-Performance Liquid Chromatography-Ultraviolet Detection (HPLC-UV). The yield of GEF extraction under the optimum MSPE conditions were 94% and 87% for water and plasma samples, respectively. The chromatographic separation was carried out isocratically at 25 °C on a Phenomenex C8 reversed phase column (150 mm × 4.6 mm, with 5 µm particle size). The proposed method was linear over concentration ranges of 15.0–300.0 and 80.0–600.0 ng/mL for water and plasma samples with limits of detection of 4.6 and 25.0 ng/mL in a respective order. Relative standard deviations (%RSD) for intra-day and inter-day were 0.75 and 0.94 for water samples and 1.26 and 1.70 for plasma samples, respectively. Using the magnetic nanoparticles (MNPs) as loaded drug-extractors made the detection of the anti-cancer drug environmentally friendly and simple and has great potential to be used for different drug-containing systems.

Dual functional monomers modified magnetic adsorbent for the enrichment of non-steroidal anti-inflammatory drugs in water and urine samples

According to the molecular properties of non-steroidal anti-inflammatory drugs (NSADs), a new adsorbent for magnetic solid phase extraction (MSPE) was designed and synthesized. Triethyl-(4-vinylbenzyl)aminium chloride and 4-vinylbenzeneboronic acid were utilized as dual functional monomers to copolymerize with divinylbenzene on the surface of pre-modified Fe₃O₄ nanoparticles. The prepared magnetic adsorbent (Fe₃O₄@TCVA) was characterized by elemental analysis, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer. Due to the abundant boronic acid, quaternary amine and phenyl groups, the Fe₃O₄@TCVA displayed satisfactory extraction performance for target NSADs (diclofenac acid, ibuprofen and mefenamic acid) by means of B-N coordination, anion-exchange, π-π and hydrophobic interactions. Under the optimized conditions, the Fe₃O₄@TCVA/MSPE was combined with high-performance liquid chromatography with diode array detection (HPLC-DAD) to sensitively analyze NSADs in water and human urine samples. Results indicated that the limits of detection for water and urine samples were in the ranges of 0.014-0.031 μg/L and 0.029-0.11 μg/L, respectively. The relative standard deviations for the intra-day and inter-day assay variability were below 10%. The applicability of the proposed Fe₃O₄@TCVA/MSPE-HPLC-DAD method was demonstrated by the successful extraction and quantification of trace levels of NSADs in real water and human urine samples. Satisfactory spiked recovery and reproducibility were achieved.

Simultaneous magnetic dispersive micro solid phase extraction of valsartan and atorvastatin using a CMC-coated Fe3O4 nanocomposite prior to HPLC-UV detection: multivariate optimization

In this study, a sensitive, rapid, accurate and practical procedure is established for determination of atorvastatin and valsartan from human biological fluids by dispersive micro solid phase extraction (D-μ-SPE) combined with HPLC-UV detector.

Mixed hemimicelles solid-phase extraction based on sodium dodecyl sulfate-coated nano-magnets for selective adsorption and enrichment of illegal cationic dyes in food matrices prior to high-performance liquid chromatography-diode array detection detection

In this study, mixed hemimicelles solid-phase extraction (MHSPE) based on sodium dodecyl sulfate (SDS) coated nano-magnets Fe3O4 was investigated as a novel method for the extraction and separation of four banned cationic dyes, Auramine O, Rhodamine B, Basic orange 21 and Basic orange 22, in condiments prior to HPLC detection. The main factors affecting the extraction of analysts, such as pH, surfactant and adsorbent concentrations and zeta potential were studied and optimized. Under optimized conditions, the proposed method was successful applied for the analysis of banned cationic dyes in food samples such as chili sauce, soybean paste and tomato sauce. Validation data showed the good recoveries in the range of 70.1-104.5%, with relative standard deviations less than 15%. The method limits of determination/quantification were in the range of 0.2-0.9 and 0.7-3μgkg(-1), respectively. The selective adsorption and enrichment of cationic dyes were achieved by the synergistic effects of hydrophobic interactions and electrostatic attraction between mixed hemimicelles and the cationic dyes, which also resulted in the removal of natural pigments interferences from sample extracts. When applied to real samples, RB was detected in several positive samples (chili powders) within the range from 0.042 to 0.177mgkg(-1). These results indicate that magnetic MHSPE is an efficient and selective sample preparation technique for the extraction of banned cationic dyes in a complex matrix.

Magnetic solid-phase extraction based on modified ferum oxides for enrichment, preconcentration, and isolation of pesticides and selected pollutants

Recently, a simple, rapid, high-efficiency, selective, and sensitive method for isolation, preconcentration, and enrichment of analytes has been developed. This new method of sample handling is based on ferum oxides as magnetic nanoparticles (MNPs) and has been used for magnetic solid-phase extraction (MSPE) of various analytes from various matrices. This review focuses on the applications of modified ferum oxides, especially modified Fe3O4 MNPs, as MSPE adsorbent for pesticide isolation from various matrices. Further perspectives on MSPE based on modified Fe3O4 for inorganic metal ions, organic compounds, and biological species from water samples are also presented. Ferum(III) oxide MNPs (Fe2O3) are also highlighted.

Magnetic scavengers as carriers of analytes for flowing atmospheric pressure afterglow mass spectrometry (FAPA-MS)

In this paper, a procedure for the preconcentration and transport of mixtures of acids, bases, and drug components to a mass spectrometer using magnetic scavengers is presented. Flowing atmospheric pressure afterglow mass spectrometry (FAPA-MS) was used as an analytical method for identification of the compounds by thermal desorption from the scavengers. The proposed procedure is fast and cheap, and does not involve time-consuming purification steps. The developed methodology can be applied for trapping harmful substances in minute quantities, to transport them to specialized, remotely located laboratories.

Microextraction with phases containing nanoparticles

In this article, the state of the art of microextraction techniques that involve nanoparticles or nanomaterials (NPs) is reviewed, with special emphasis on the applications described in the biomedical field. The uses and advantages of the different types of NPs such as carbon nanotubes (either single- and multi-walled) and other carbon-based materials, metallic NPs, including gold, silver and magnetic NPs, and silica NPs are summarized. The main strategies used to modify the selectivity, extractive capacity and/or the stability of NPs through a chemical reaction are also reviewed. The potential advantages of NPs in different forms of off-line and on-line microextraction are discussed, and illustrative examples of application in the biomedical field are shown.

Surfactant-enhanced spectrofluorimetric determination of total aflatoxins from wheat samples after magnetic solid-phase extraction using modified Fe₃O₄ nanoparticles

The extraction and preconcentration of total aflatoxins (including aflatoxin B1, B2, G1, and G2) using magnetic nanoparticles based solid phase extraction (MSPE) followed by surfactant-enhanced spectrofluorimetric detection was proposed. Ethylene glycol bis-mercaptoacetate modified silica coated Fe3O4 nanoparticles as an efficient antibody-free adsorbent was successfully applied to extract aflatoxins from wheat samples. High surface area and strong magnetization properties of magnetic nanoparticles were utilized to achieve high enrichment factor (97), and satisfactory recoveries (92-105%) using only 100mg of the adsorbent. Furthermore, the fast separation time (less than 10 min) avoids many time-consuming cartridge loading or column-passing procedures accompany with the conventional SPE. In determination step, signal enhancement was performed by formation of Triton X-100 micelles around the analytes in 15% (v/v) acetonitrile-water which dramatically increase the sensitivity of the method. Main factors affecting the extraction efficiency and signal enhancement of the analytes including pH of sample solution, desorption conditions, extraction time, sample volume, adsorbent amount, surfactant concentration and volume and time of micelle formation were evaluated and optimized. Under the optimum conditions, wide linear range of 0.1-50 ng mL(-1) with low detection limit of 0.03 ng mL(-1) were obtained. The developed method was successfully applied to the extraction and preconcentration of aflatoxins in three commercially available wheat samples and the results were compared with the official AOAC method.

Selenium speciation using capillary electrophoresis coupled with modified electrothermal atomic absorption spectrometry after selective extraction with 5-sulfosalicylic acid functionalized magnetic nanoparticles

A new method for selenium speciation in fermented bean curd wastewater and juice was described. This method involved sample extraction with 5-sulfosalicylic acid (SSA)-functionalized silica-coated magnetic nanoparticles (SMNPs), capillary electrophoresis (CE) separation, and online detection with a modified electrothermal atomic absorption spectrometry (ETAAS) system. The modified interface for ETAAS allowed for the introduction of CE effluent directly through the end of the graphite tube. Elimination of the upper injection hole of the graphite tube reduced the loss of the anlayte and enhanced the detection sensitivity. The SSA-SMNPs were synthesized and used to extract trace amounts of selenite [Se(IV)], selenite [Se(VI)], selenomethionine (SeMet), and selenocystine (SeCys2) from dilute samples. The concentration enrichment factors for Se(VI), Se(IV), SeMet, and SeCys2 were 21, 29, 18, and 12, respectively, using the SSA-SMNPs extraction. The limits of detection for Se(VI), Se(IV), SeMet, and SeCys2 were 0.18, 0.17, 0.54, 0.49ngmL(-1), respectively. The RSD values (n=6) of method for intraday were observed between 0.7% and 2.9%. The RSD values of method for interday were less than 3.5%. The linear range of Se(VI) and Se(IV) were in the range of 0.5-200ngmL(-1), and the linear ranges of SeMet and SeCys2 were 2-500 and 2-1000ngmL(-1), respectively. The detection limits of this method were improved by 10 times due to the enrichment by the SSA-SMNP extraction. The contents of Se(VI) and Se(IV) in fermented bean curd wastewater were measured as 3.83 and 2.62ngmL(-1), respectively. The contents of Se(VI), Se(IV), SeMet, and SeCys2 in fermented bean curd juice were determined as 6.39, 4.08, 2.77, and 4.00ngmL(-1), respectively. The recoveries were in the range of 99.14-104.5% and the RSDs (n=6) of recoveries between 0.82% and 3.5%.

Magnetic adsorbents based on micro- and nano-structured materials

Micro- and nano-sized magnetic adsorbents based on elemental metals, iron oxides, and ferrites and supported by inorganic (carbon, graphene, silica, and zeolites) or organic (macromolecules, polysaccharides, and biomolecules) compounds are reviewed.

Magnetically assisted solid phase extraction using Fe3O4 nanoparticles combined with enhanced spectrofluorimetric detection for aflatoxin M1 determination in milk samples

A novel, facile and inexpensive solid phase extraction (SPE) method using ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol grafted Fe(3)O(4) nanoparticles coupled with spectrofluorimetric detection was proposed for determination of aflatoxin M1 (AFM1) in liquid milk samples. The method uses the advantage fluorescence enhancement by β-cyclodexterin complexation of AFM1 in 12% (v/v) acetonitrile-water and the remarkable properties of Fe(3)O(4) nanoparticles namely high surface area and strong magnetization were utilized to achieve high enrichment factor (57) and satisfactory extraction recoveries (91-102%) using only 100 mg of magnetic adsorbent. Furthermore, fast separation time of about 15 min avoids many time-consuming column-passing procedures of conventional SPE. The main factors affecting extraction efficiency including pH value, desorption conditions, extraction/desorption time, sample volume, and adsorbent amount were evaluated and optimized. Under the optimal conditions, a wide linear range of 0.04-8 ng mL(-1) with a low detection limit of 0.015 ng mL(-1) was obtained. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method.

Carbon dots as nanoantennas for anti-inflammatory drug analysis using surface-assisted laser desorption/ionization time-of-flight mass spectrometry in serum

C-dots assisted LDI MS method has been developed for the detection of Mefenamic acid in serum.