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

Optimization of Cyanocobalamin (Vitamin B12) Sorption onto Mesoporous Superparamagnetic Iron Oxide Nanoparticles

The techniques used to detect and quantify cyanocobalamin (vitamin B12) vary considerably in terms of detection sensitivity, from the most sensitive, based on radioisotopes and mass spectrometry (MS) with limits of detection (LOD) in fg mL-1, to fluorescence (FL) and surface plasmon resonance (SPR) biosensors with LOD values in the range of a few µg mL-1. For accurate quantification of an analyte present at trace levels in complex biological matrices, a selective separation and enrichment step is required to overcome matrix interferences and ensure sufficient detection sensitivity. In this study, iron oxide magnetic nanoparticles (IONPs) were used for the extraction and initial preconcentration of cyanocobalamin (vitamin B12). In the dependence of the magnetization on the H-field (hysteresis loop), no coercivity and remanence values were found at 300 K, indicating the superparamagnetic properties of the tested IONPs. Perfluorinated acids were used as amphiphilic agents to allow the sorption of cyanocobalamin onto the IONPs. FT-IR/ATR spectroscopy was used to confirm the sorption of cyanocobalamin on the IONPs. The influence of the addition of a homologous series of perfluorinated acids such as trifluoroacetic acid (TFAA), heptafluorobutyric acid (HFBA), and trichloroacetic acid (TCAA) to the extraction mixture was tested considering their type, mass, and time required for effective sorption. The adsorption kinetics and isotherm, described by the Freundlich and Langmuir equations, were analyzed. The maximum adsorption capacity (qm) exceeded 6 mg g-1 and was 8.9 mg g-1 and 7.7 mg g-1 for HFBA and TCAA, respectively, as the most efficient additives. After the desorption process using aqueous KH2PO4 solution, the sample was finally analyzed spectrophotometrically and chromatographically. The IONP-based method was successfully applied for the isolation of cyanocobalamin from human urine samples. The results showed that the developed approach is simple, cheap, accurate, and efficient for the determination of traces of cyanocobalamin in biological matrices.

Biocompatible magnetite nanoparticles coated with ionic liquid-based surfactantas a hydrophilic sorbent for dispersive solid phase microextraction of cephalosporins prior to their quantitation by HPTLC

Extraction of highly hydrophilic compounds from biological fluids including urine or plasma samples is a dilemma due to high hydrophilicity of the matrix itself. The main aim of the current work is to explore the competence of ionic liquid (IL)-based surfactant-coated mineral oxide nanoparticles (NPs) in dispersive solid-phase microextraction (d-SPME) of highly hydrophilic analytes taking cefoperazone (CPZ) as a model analyte for the study. The IL-based surfactant coated Fe₃O₄ NPs is utilized as an innovative adsorbent for the separation and pre-concentration of CPZ after intramuscular injection (I.M) in rabbits. The utilized magnetite NPs were synthesized via simple and reliable co-precipitation procedure, which doesn't require any air-free environment and depends on a single iron (III) salt. Characterization of the as-synthesized NPs was achieved by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) and energy dispersive X-ray (EDX). Surface area measurements show that Fe₃O₄ NPs have large surface area of 75 m² g^-1. The developed approach utilizes the unique properties of the IL-based surfactant including multiple polar interaction types provided by the polar head in addition to merits of Fe₃O₄ nanoparticles, which include large adsorptive capacity and magnetic properties, to improve separation, save time, and achieve satisfactory recovery. Comprehensive study was developed for the factors, that affect the adsorption capacity such as pH, NPs amount, IL-based surfactant concentration, ionic strength, adsorption time, and desorption conditions. Moreover, the adsorption data was fitted to Langmuir and second-order kinetic models as reflected by the reasonable determination coefficients of 0.9319 and 0.9726, respectively. Under the optimized conditions, the developed approach achieves good correlation coefficient of 0.9975, and 0.9981 over linearity range of 0.7-12.0 and 4.0-50.0 µg mL^-1 for both CPZ standard solutions and spiked rabbit plasma, respectively. It also provides good sensitivity expressed by the low values of limit of detection (LOD) of 0.2 and 1.2 µg mL^-1 and limit of quantitation (LOQ) of 0.7 and 4.0 µg mL^-1 for both the standard solutions and spiked plasma, respectively. The developed approach was also applied successfully for monitoring CPZ in rabbit plasma samples with satisfactory recovery % (83-110). In addition, a detailed pharmacokinetic study is performed where pharmacokinetic parameters of CPZ in rabbit plasma samples were calculated.

Fast Determination of Carbamates in Environmental Water Based on Magnetic Molecularly Imprinted Polymers as Adsorbent

Magnetic molecularly imprinted polymers (MMIPs) were prepared with isoprocarb as template molecule and applied to extraction of carbamates pesticides in different water samples. This method based on magnetic solid-phase extraction (SPE) avoided the time-consuming column-passing process of loading large volume samples in conventional SPE. In the study, only 0.1 g MMIPs could be used to obtain satisfactory recoveries, due to the high-surface area and excellent adsorption capacity of these nano-magnetic adsorbents. Owing to the excellent selectivity of MMIPs, in high-performance liquid chromatography-mass spectrometry analysis, the matrix effects of this technique were obviously lower than the conventional SPE method. Under the optimal conditions, the detection limits of carbamates were in the range of 2.7-11.7 ng L-1. The relative standard deviations of intra-day and inter-day were 2.5-7.4% and 3.6-8.4%, respectively. At all the spiked level, the recoveries of four analyzed carbamates in environmental water samples were in the range of 74.2-94.2%. The significant positive results were achieved in the proposed method for the determination of four carbamates in water samples from different lakes and rivers. In the three samples we tested, the carbaryl was found in the lake water obtained from Yitong River, and the content was 2.4 ng L-1.

Magnetite nanoparticles grafted with murexide-terminated polyamidoamine dendrimers for removal of lead (II) from aqueous solution: synthesis, characterization, adsorption and antimicrobial activity studies

In this study, new, efficient, eco-friendly and magnetically separable nanoadsorbents, MNPs-G1-Mu and MNPs-G2-Mu, were successfully prepared by covalently grafting murexide-terminated polyamidoamine dendrimers on 3-aminopropyl functionalized silica-coated magnetite nanoparticles, and used for rapid removal of lead (II) from aqueous medium. After each adsorption process, the supernatant was successfully acquired from reaction mixture by the magnetic separation, and then analyzed by employing ICP-OES. Chemical and physical characterizations of new nanomaterials were confirmed by XRD, FT-IR, SEM, TEM, and VSM. Maximum adsorption capacities (q_m) of both prepared new nanostructured adsorbents were compared with each other and also with some other adsorbents. The kinetic data were appraised by using pseudo-first-order and pseudo-second-order kinetic models. Adsorption isotherms were found to be suitable with both Langmuir and Freundlich isotherm linear equations. The maximum adsorption capacities for MNPs-G1-Mu and MNPs-G2-Mu were calculated as 208.33 mg g^-1 and 232.56 mg g^-1, respectively. Antimicrobial activities of nanoparticles were also examined against various microorganisms by using microdilution method. It was determined that MNPs-G1-Mu, MNPs-G2-Mu and lead (II) adsorbed MNPs-G2-Mu showed good antimicrobial activity against S. aureus ATTC 29213 and C. Parapsilosis ATTC 22019. MNPs-G1-Mu also showed antimicrobial activity against C. albicans ATTC 10231.

Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization

In this study, we successfully coated cetyltrimethylammonium–silica on magnetite. The material produced is used to degrade phenol waste in the waters. The effect of the addition of cetyltrimethylammonium bromide (CTAB) on the ability of phenol adsorption was assessed through changes in CTAB concentration of 1, 5, and 10 mM. The results of Fourier-transform infrared spectroscopy explain that CTAB has electrostatic interactions with the silica surface, which is induced by opposite-loaded patches on the opposite surface of silica oxide. The results of the vibrating sample magnetometer show that the magnetite that has been coated by silica–CTA has magnetic properties that are weaker than the initial magnetite, which indicates that the silica–CTA layer has blocked the magnetite. Based on the measurement of the gas sorption analyzer, the largest pore size is in the micro-mesh region, which is between 2 and 6 nm. All magnetite-silica–cetyltrimethylammonium (MS–CTA) showed good adsorption ability of phenol and correlated with the amount of loaded CTAB and admicelle density of the adsorbent. The amount of phenol adsorbed increases proportionately with the increasing density of CTAB admicelles. The maximum phenol adsorption capacity (0.93 mg g−1 adsorbent) is achieved by MS–CTA prepared at a CTAB concentration of 10 mM.

Lab and Pilot-Scale Synthesis of MxOm@SiC Core-Shell Nanoparticles

The addition of light ceramic particles to bulk technological materials as reinforcement to improve their mechanical properties has attracted increasing interest in the last years. The metal matrix composites obtained using nanoparticles have been reported to exhibit an improvement of their properties due to the decrease in the size of the ceramic additives to the nanoscale. Additionally, important effects such as the dispersion of the nanoparticles, wettability, and low reactivity can be controlled by the modification of the nanoparticles' surface. In this work, we present the preparation of core-shell M_xO_m@SiC nanoparticles with different shell compositions. The accurate and reproducible preparation is developed both at the lab and pilot scale. The synthesis of these core-shell nanoparticles and their scale-up production are fundamental steps for their industrial use as additives in metal matrix composites and alloys. Powder X-ray diffraction and energy dispersive X-ray (EDX) coupled with scanning transmission electron microscopy (STEM) are used to corroborate the formation of the core-shell systems, whereas line scan-EDX analysis allows measuring the average shell thickness.

Dispersive admicelle solid-phase extraction based on sodium dodecyl sulfate coated Fe3 O4 nanoparticles for the selective adsorption of three alkaloids in Gegen-Qinlian oral liquid before high-performance liquid chromatography

A novel dispersive admicelle solid-phase extraction method based on sodium dodecyl sulfate-coated Fe₃ O₄ nanoparticles was developed for the selective adsorption of berberine, coptisine, and palmatine in Gegen-Qinlian oral liquid before high-performance liquid chromatography. Fe₃ O₄ nanoparticles were synthesized by a chemical coprecipitation method and characterized by using transmission electron microscopy. Under acidic conditions, the surface of Fe₃ O₄ nanoparticles was coated with sodium dodecyl sulfate to form a nano-sized admicelle magnetic sorbent. Owing to electrostatic interaction, the alkaloids were adsorbed onto the oppositely charged admicelle magnetic nanoparticles. The quick separation of the analyte-adsorbed nanoparticles from the sample solution was performed by using Nd-Fe-B magnet. Best extraction efficiency was achieved under the following conditions: 800 μL Fe₃ O₄ nanoparticles suspension (20 mg/mL), 150 μL sodium dodecyl sulfate solution (10 mg/mL), pH 2, and vortexing time 2 min for the extraction of alkaloids from 10 mL of diluted sample. Four hundred microliters of methanol was used to desorb the alkaloids by vortexing for 1 min. Satisfactory extraction recoveries were obtained in the range of 85.9-120.3%, relative standard deviations for intra- and interday precisions were less than 6.3 and 10.0%, respectively. Finally, the established method was successfully applied to analyze the alkaloids in two batches of Gegen-Qinlian oral liquids.

Magnetic mixed hemimicelle solid-phase extraction based on mixed hemi-/ad-micelle SDS-coated magnetic nanoparticles Fe2-xAlxO3 (x = 0.4) for the fluorimetric determination of carvedilol in biological samples

Mixed hemi-/ad-micelle SDS-coated magnetic nanoparticles (Fe2-xAlxO3 (x = 0.4)) were used as an efficient adsorbent for the extraction and preconcentration of carvedilol (CVD) based on magnetic mixed hemimicelle solid-phase extraction. The Fe2-xAlxO3 magnetic nanoparticles not only have better stability and resistance to acidity, as well as alkalinity, but also are easy to prepare, inexpensive, and environmentally friendly. Several parameters that affected the extraction efficiency were investigated, including the type and volume of desorption solvent, extraction and desorption times, pH of the solution, zeta potential, and amounts of adsorbent and surfactant. Under the optimized extraction conditions, the developed method showed good linearity (R2 = 0.9998) within the range of 0.02–2.7 ng mL−1, and the limit of detection was 0.009 ng mL−1. The spiked recoveries of CVD in urine and plasma samples ranged from 101.50% to 111.00%. To the best of our knowledge, this is the first time that a mixed hemi-/ad-micelle solid-phase extraction method based on magnetic separation and nanoparticles has been used as a simple and sensitive method for the monitoring of CVD in biological samples.

Superparamagnetic graphene oxide-based dispersive-solid phase extraction for preconcentration and determination of tamsulosin hydrochloride in human plasma by high performance liquid chromatography-ultraviolet detection

In the present study, superparamagnetic graphene oxide-Fe₃O₄ nanocomposites were successfully prepared by a modified impregnation method (MGO_mi) and their application as a sorbent in the magnetic-dispersive solid phase extraction (M-dSPE) mode to the preconcentration and determination of tamsulosin hydrochloride (TMS) in human plasma was investigated by coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV). The structure, morphology and magnetic properties of the prepared nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Some factors affecting the extraction efficiency, including the pH value, amount of sorbent, extraction time, elution solvent and its volume, and desorption time were studied and optimized. Magnetic nanocomposites plasma extraction of TMS following HPLC analyses showed a linear calibration curve in the range of 0.5-50.0ngmL^-1 with an acceptable correlation coefficient (R²=0.9988). The method was sensitive, with a low limit of detection (0.17ngmL^-1) and quantification (0.48ngmL^-1). Inter- and intra-day precision expressed as relative standard deviation (n=3) and the preconcentration factor, were found to be 5.6-7.2%, 2.9-4.2% and 10, respectively. Good recoveries (98.1-101.4%) with low relative standard deviations (4.2-5.0%) indicated that the matrices under consideration do not significantly affect the extraction process. Due to its high precision and accuracy, the developed method may be a HPLC-UV alternative with M-dSPE for bioequivalence analysis of TMS in human plasma.

Platform construction and extraction mechanism study of magnetic mixed hemimicelles solid-phase extraction

Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What’s more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples.

Mixed hemimicelles solid-phase extraction of cephalosporins in biological samples with ionic liquid-coated magnetic graphene oxide nanoparticles coupled with high-performance liquid chromatographic analysis

A novel mixed hemimicelles solid phase extraction based on magnetic graphene oxide (Fe3O4/GO) and ionic liquid (IL) was developed for the simultaneous extraction and determination of trace cephalosporins in spiked human urine. The high surface area and excellent adsorption capacity of the graphene oxide after modification with1-hexadecyl-3-methylmidazoliumbromide(C16mimBr) were utilized adequately in the solid phase extraction(SPE) process. A comprehensive study of the parameters affecting the extraction recovery, such as the zeta-potential of magnetic graphene oxide, amounts of magnetic graphene oxide and surfactant, pH of solution, ionic strength, extraction time, and desorption condition were optimized. A comparative study on the use of different surfacant-coated Fe3O4/GO NPs as sorbents was presented. Good linearity (R(2)>0.9987) for all calibration curves was obtained. The LODs were ranged between 0.6 and 1.9ng mL(-1) for the cephalosporins and the LOQs were 1.5 to 5.5, respectively. Satisfactory recoveries(84.3% to 101.7%)and low relative standard deviations from 1.7% to 6.3% in biological matrices were achieved. The mixed hemimicelles magnetic SPE (MSPE) method based on ILs and Fe3O4/GO NPs magnetic separation has ever been successfully used for pretreatment of complex biological samples.

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 ionic liquid in stirring-assisted drop-breakup microextraction: Proof-of-concept extraction of phenolic endocrine disrupters and acidic pharmaceuticals

The use of magnetic ionic liquids (MILs) is in constant growth due to their switchable properties in the presence of an external magnetic field along with the outstanding properties of ionic liquids. In this study, a novel stirring-assisted drop-breakup microextraction (SADBME) approach is put forward, based on the synthesis and utilization of methyltrioctylammonium tetrachloroferrate (N8 8,8,1[FeCl4]), as a MIL. The proposed procedure complies with the principles of the green chemistry, since it uses low volumes of easily synthesized ILs-based magnetic extracting phases avoiding the use of toxic solvents. To demonstrate its applicability, the proposed microextraction procedure is studied in conjunction with HPLC for the determination of selected phenols and acidic pharmaceuticals in aqueous matrices, taking into account the main experimental variables involved. The results obtained are accurate and highly reproducible, thus making it a good alternative approach for routine analysis of phenols and acidic pharmaceuticals. The low-cost approach is straightforward, environmentally safe and exhibits high enrichment factors and absolute extraction percentages and satisfactory recoveries. To the best of our knowledge, this is the first time that a MIL is used for analytical purposes in a practical, efficient and environmentally friendly drop-breakup microextraction approach for small molecules.

Mixed hemimicelles solid-phase extraction based on sodium dodecyl sulfate (SDS)-coated nano-magnets for the spectrophotometric determination of Fingolomid in biological fluids

In this study, mixed hemimicelles solid-phase extraction (SPE) based on sodium dodecyl sulfate (SDS)-coated nano-magnets Fe3O4 was investigated as a novel method for the separation and determination of Fingolimod (FLM) in water, urine and plasma samples prior to spectrophotometeric determination. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS, satisfactory extraction recoveries can be produced. The main factors affecting the adsolubilization of analysts, such as pH, surfactant and adsorbent amounts, ionic strength, extraction time and desorption conditions were studied and optimized. Under the selected conditions, FLM has been quantitatively extracted. The accuracy of the method was evaluated by recovery measurements on spiked samples, and good recoveries of 96%, 95% and 88% were observed for water, urine and plasma respectively. Proper linear behaviors over the investigated concentration ranges of 2-26, 2-17 and 2-13 mg/L with good coefficients of determination, 0.998, 0.997 and 0.995 were achieved for water, urine and plasma samples, respectively. To the best of our knowledge, this is the first time that a mixed hemimicelles SPE method based on magnetic separation and nanoparticles has been used as a simple and sensitive method for monitoring of FLM in water and biological samples.

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.

Superparamagnetic Fe3 O4 @SiO2 core-shell composite nanoparticles for the mixed hemimicelle solid-phase extraction of benzodiazepines from hair and wastewater samples before high-performance liquid chromatography analysis

Magnetic Fe3 O4 /SiO2 composite core-shell nanoparticles were synthesized, characterized, and applied for the surfactant-assisted solid-phase extraction of five benzodiazepines diazepam, oxazepam, clonazepam, alprazolam, and midazolam, from human hair and wastewater samples before high-performance liquid chromatography with diode array detection. The nanocomposite was synthesized in two steps. First, Fe3 O4 nanoparticles were prepared by the chemical co-precipitation method of Fe(III) and Fe(II) as reaction substrates and NH3 /H2 O as precipitant. Second, the surface of Fe3 O4 nanoparticles was modified with shell silica by Stober method using tetraethylorthosilicate. The Fe3 O4 /SiO2 composite were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. To enhance their adsorptive tendency toward benzodiazepines, cetyltrimethylammonium bromide was added, which was adsorbed on the surface of the Fe3 O4 /SiO2 nanoparticles and formed mixed hemimicelles. The main parameters affecting the efficiency of the method were thoroughly investigated. Under optimum conditions, the calibration curves were linear in the range of 0.10-15 μgmL(-1) . The relative standard deviations ranged from 2.73 to 7.07%. The correlation coefficients varied from 0.9930 to 0.9996.

Simultaneous removal of binary mixture of Brilliant Green and Crystal Violet using derivative spectrophotometric determination, multivariate optimization and adsorption characterization of dyes on surfactant modified nano-γ-alumina

The present study deals with the simultaneous removal of Brilliant Green (BG) and Crystal Violet (CV) by surfactant-modified alumina. The utilization of alumina nanoparticles with an anionic surfactant (sodium dodecyl sulfate (SDS)) as a novel and efficient adsorbent is successfully carried out to remove two cationic dyes from aqueous solutions in binary batch systems. A first-order derivative spectrophotometric method is developed for the simultaneous determination of BG and CV in binary solutions. The linear concentration range and limits of detection for the simultaneous determination of BG and CV were found to be: 1-20, 1-15 mg/L, 0.3 and 0.5 mg/L, respectively. The influence of various parameters, such as contact time, initial concentration of dyes and sorbent mass on the dye adsorption is investigated. A response surface methodology achieved through performing the Box-Behnken design is utilized to optimize the removal of dyes by surfactant-modified nanoparticle alumina through a batch adsorption process. The proposed quadratic model resulting from the Box-Behnken design approach fitted very well with the experimental data. The optimal conditions for dye removal were contact time t=50 min, sorbent dose=0.036 g, CBG (Initial BG concentration)=215 mg/L and CCV (Initial CV concentration)=170 mg/L. Furthermore, FT-IR analysis, the isotherms and kinetics of adsorption were also explored.

Extraction of Sudan dyes from environmental water by hemimicelles-based magnetic titanium dioxide nanoparticles

A novel method for the extraction of Sudan dyes including Sudan I, II, III, and IV from environmental water by magnetic titanium dioxide nanoparticles (Fe3O4@TiO2) coated with sodium dodecylsulfate (SDS) as adsorbent was reported. Fe3O4@TiO2 was synthesized by a simple method and was characterized by transmission electron microscopy, Fourier-transform infrared spectrometry, and vibrating sample magnetometer. The magnetic separation was quite efficient for the adsorption and desorption of Sudan dyes. The effect of the amount of SDS, extraction time, pH, desorption condition, maximal extraction volume, and humic acid on the extraction process were investigated. This method was employed to analyze three environmental water samples. The results demonstrated that our proposed method had wide linear range (25-5,000 ng L(-1)) with a good linearity (R (2) > 0.999) and low detection limits (2.9-7.3 ng L(-1)). An enrichment factor of 1,000 was achieved. In all three spiked levels (25, 250, and 2,500 ng L(-1)), the recoveries of Sudan dyes were in the range of 86.9-93.6 %. The relative standard deviations obtained were ranging from 2.5 to 9.3 %. That is to say, the new method was fast and effective for the extraction of Sudan dye from environmental water.

Dispersive micro-solid phase extraction based on self-assembling, ionic liquid-coated magnetic particles for the determination of clofentezine and chlorfenapyr in environmental water samples

Two ionic liquid-coated-Fe3O4 magnetic particles (IL-Fe3O4 MPs) were developed for use in two types of dispersive micro-solid phase extraction (D-μ-SPE) for the high-performance liquid chromatographic analysis of clofentezine and chlorfenapyr in environmental water samples. Self-assembling IL-Fe3O4 MPs were used in D-μ-SPE as adsorbents. Two D-μ-SPE extraction methods, namely, direct dispersive micro-solid phase extraction (d-D-μ-SPE) and in situ solvent formation-based dispersive micro-solid phase extraction (ISF-D-μ-SPE), were proposed, using [C8MIM][PF6] to extract analytes through two pathways. Lower IL doses were required in the extraction process compared with those in other IL-based methods. Fe3O4 MPs can also be recycled and reused after extraction and are thus environmentally friendly. These newly developed methods were demonstrated to be feasible for use in the quantitation of clofentezine and chlorfenapyr at trace levels, with lower limit of detection values ranging from 0.4 to 0.5 ng mL(-1) for d-D-μ-SPE and 0.4 ng mL(-1) for ISF-D-μ-SPE. Finally, relative standard deviations of less than 6.0% were obtained.

Development of a selective and pH-independent method for the analysis of ultra trace amounts of nitrite in environmental water samples after dispersive magnetic solid phase extraction by spectrofluorimetry

This paper describes an innovative and rapidly dispersive magnetic solid phase extraction spectrofluorimetry (DMSPE-FL) method for the analysis of trace amounts of nitrite in some environmental water samples. The method includes derivatization of aqueous nitrite with 2, 3-diaminonaphthalene (DAN), analysis of highly fluorescent 2, 3-naphthotriazole (NAT) derivative using spectrofluorimetry after DSPME. The novelty of our method is based on forming NAT that was independent with the pH-responsive and was adsorbed on MMWCNT by hydrophobic attractions in both acidic and basic media. The extraction efficiency of the sorbent was investigated by extraction of nitrite. The optimum extraction conditions for NO2(-) were obtained as of extraction time, 1.5 min; 10mg sorbent from 160 mL of the sample solution, and elution with 1 mL of acetone/KOH. Under the optimal conditions, the calibration curves were obtained in the range of 0.1-80 µg L(-1) (R(2)=0.999) and LOD (S/N=3) was obtained in 34 ng L(-1). Relative standard deviations (RSD) were 0.6 % (five replicates at 5 μg L(-1)). In addition, the feasibility of the method was demonstrated with extraction and determination of nitrite from some real samples containing tap, mineral, sea, rain, snow and ground waters, with the recovery in standard addition to real matrix of 94-102 % and RSDs of 1.8-10.6%.

Extraction and determination of trace amounts of chlorpromazine in biological fluids using magnetic solid phase extraction followed by HPLC

A simple, rapid and sensitive method termed as magnetic solid phase extraction (MSPE) combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) has been proposed for the determination of trace amounts of chlorpromazine (CPZ) in water, urine and plasma samples. The separation and determination was performed on a C18 column under the optimal chromatographic conditions. Several factors influencing the extraction efficiency of CPZ, such as pH, surfactant and adsorbent amounts, ionic strength, extraction time, sample volume and desorption conditions, were studied and optimized. Under the optimal MSPE conditions, the extraction percentage of CPZ was 74%, 27% and 16% in water, urine and plasma samples, respectively. The limits of detection (LODs) of the proposed approach were 0.1, 5.0 and 10 ng/mL in water, urine and plasma samples, respectively. The relative standard deviations (RSDs) based on five replicate determinations at 10 ng/mL level of CPZ was 1.2%. Good linear behaviors over the investigated concentration ranges (0.25-300 ng/mL) with good coefficient of determination, R²>0.9998, were obtained. Good spike recoveries with relative errors less than 9.0% were obtained when applying the proposed method to water, urine and plasma samples.