Preparation of Ferrofluid from Adipic Acid Coated Magnetic Nanoparticles and Hydrophobic Deep Eutectic Solvent Used in Dispersive Micro-Solid-Phase Extraction: Application for the Pre-Concentration and Determination of Clozapine in Biological Samples.

The aim of the present study is the preparation of a novel magnetic ferrofluid (FF) based on a hydrophobic deep eutectic solvent (DES), which is used for the extraction of trace quantities of clozapine from biological samples. For this purpose, a highly stable FF was prepared through the combination of adipic acid-coated magnetic nanoparticles (MNPs) plus tetraethylammonium chloride/thymol hDES without an additional stabilizer. These solvents were synthesized by the available and less-toxic materials, which is the appropriate option to support the solvents for the preparation of FF. In this study, a water-immiscible DES acts simultaneously as a carrier and stabilizer for the MNPs. In addition, the strong interactions between clozapine and magnetic FF could increase the extraction efficiency. The fractional factorial design was used for screening the experimental parameters. Then, the effective factors were optimized using the Box-Behnken design. The optimum extraction conditions were the following: pH of the sample solution: 8, the volume of the desorption solvent: 200 µL and desorption time: 5 min. Moreover, the suggested method exhibited low limits of detection in the range of 2.8-3.1 µg L-1. The linear range was 10.0-500.0 µg L-1 for human plasma and urine samples with acceptable recoveries greater than 91.4%. In addition, the proposed method is convenient, sensitive, effective, rapid and environmentally friendly.

Development of magnetic solid phase extraction based on magnetic chitosan-graphene oxide nanoparticles and deep eutectic solvents for the determination of flavonoids by high performance liquid chromatography.

An environmentally friendly magnetic solid phase extraction method was developed based on magnetic chitosan-graphene oxide nanoparticles and deep eutectic solvents (DESs) for the pre-concentration and isolation of flavonoids (apigenin, morin, naringenin, and quercetin) of natural orange juice, commercial apple juice, onion juice, green tea, and natural apple juice samples. DESs via hydrophilic and π-π interactions could increase the extraction performance. The immobilization of chitosan-graphene oxide on the surface of Fe3O4 nanoparticles improved their chemical properties and mechanical stability. In addition, the prepared magnetic nanoparticles with the hydrophilic polymeric network and the high surface area of the graphene oxide increased the access of binding sites and extraction performance. The use of DESs as desorption of solvent and the individual properties of MANPs provided the ability for high extraction recovery and accelerates the time to reach equilibrium. The principal variables that influence microextraction efficiency, including the extraction time, type of DES, stirring rate, desorption time, type of eluent solvent, and pH of the sample solution, were screened via the Plackett-Burman design and then the variables were optimized by the Box-Behnken design. Under the optimum conditions obtained, the developed method showed a good working range (R2 ≥ 0.9962). The limit of detection (LOD) and the limit of quantification (LOQ) ranged from 0.03 µg L-1 (morin) to 0.14 µg L-1 (naringenin) and from 0.09 µg L-1 (morin) to 0.46 µg L-1 (naringenin) variables, respectively. The intraday precision was in the range of 4.1-4.8. In order to experiment with the precision and applicability of the MSPE-DES method, spiking recovery studies were performed in beverages and vegetable samples (natural orange juice, onion juice, commercial apple juice, natural apple juice, and green tea). The recovery results for real samples were calculated as 90-102%.

Nanofluid of magnetic-activated charcoal and hydrophobic deep eutectic solvent: Application in dispersive magnetic solid-phase extraction for the determination and preconcentration of warfarin in biological samples by high-performance liquid chromatography.

In this study, for the first time, nanofluid of magnetic-activated charcoal and hydrophobic deep eutectic solvent (AC@Fe3 O4 -DES) based dispersive magnetic solid-phase extraction was successfully applied for the determination and preconcentration of warfarin in plasma and urine samples. The hydrophobic DES was prepared by mixing tetramethylammonium chloride (as hydrogen bond acceptor) and thymol (as hydrogen bond donor) and acted simultaneously as both carrier and stabilizer for magnetic nanoparticles. In this method, the nanofluid as a new extraction solvent was rapidly injected into the aqueous sample, which led to improvement of the mass transfer of the analytes into the sorbent and reduction of the extraction time. In the screening step, the fractional factorial design was applied for selecting some important parameters which significantly affected the extraction procedure. The effective parameters were then optimized by Box-Behnken design. Under the optimal conditions, the limits of detection were in the range of 0.3-1.6 ng/ml. A good linear range was observed in the range of 1.0-500.0 ng/ml for water and 5.0-500.0 ng/ml for urine and plasma. The intra- and inter-day relative standard deviations were 2.7-3.2 and 1.9-4.5% for five replications, respectively. Based on the results, the proposed method was successfully applied for the determination of warfarin in biological samples, using high-performance liquid chromatography.

Polyvinylidene difluoride film with embedded poly(amidoamine) modified graphene oxide for extraction of chlorpyrifos and diazinon.

An effective, sensitive, relatively fast, and cost-effective method was developed to determine two types of selected organophosphorus pesticides (OPPs) including diazinon and chlorpyrifos in apple, peach, and four different water samples (river, sea, well, and agriculture wastewater samples) through applying poly(amidoamine)@graphene oxide-reinforced polyvinylidene difluoride thin-film microextraction (PAMAM@GO-PVDF-TFME). The extracted analytes were desorbed via organic solvent and determined using high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The strong interactions between the sorbent and selected analytes (coordination bonds, intermolecular hydrogen bonding, π-π interactions, and hydrophobic effects) made this TFME capable of high extraction performance and capacity. Several factors involved in the PAMAM@GO-PVDF-TFME experiments such as desorption volume, desorption time, sample pH, extraction time, and stirring rate were screened via Plackett-Burman design and then optimized through Box-Behnken design with the purpose of reaching the highest extraction efficiency. The above method showed a good linear range (0.5-500 µg L-1 and 1-500 µg L-1) with the coefficient of determination better 0.9944, low limits of determination (0.12 and 0.20 µg L-1), good enrichment factors (99 and 98), acceptable extraction recoveries (99 and 98%), and good spiking recoveries (90-98%) under the optimized condition at three different spike levels for chlorpyrifos and diazinon, respectively. The results confirmed that the presented method would be promising for the determination of various types of these pesticides in environmental and beverage 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%.

Simultaneous extraction and analysis of clozapine and lorazepam from human plasma using dual solvent-stir bar microextraction with different acceptor phases followed by high-performance liquid chromatography ultra-violet detection.

A new design of dual solvent stir bar microextraction (DSSBME) was developed and combined with HPLC-UV for the simultaneous extraction of clozapine (CLZ) and lorazepam (LRP) from human plasma with different acceptor phases. Two short hollow fibers immobilized with an organic extraction solvent were used as the solvent bars for microextraction of CLZ and LRP from the sample solution. The solvent bars were fixed with a staple pin which served as the stirrer. The target analytes were simultaneously and selectively extracted from the sample solution into their corresponding solvent bar. Extraction parameters such as organic solvent type, pH of the sample solution, the acceptor phase concentration, salt incorporation into the solution, stirring rate, and extraction time were optimized to achieve the best extraction results. Under the optimum conditions (1-undecanol as extraction solvent, pH of sample solution = 9.0, 10% w/v NaCl, concentration of HCl = 10 mM, concentration of NaOH = 100 mM, stirring rate of 1400 rpm and extraction time of 30 min at ambient temperature) the limit of detection for CLZ was 0.4 ng mL-1 and for LRP it was 1.1 ng mL-1. The linear range for CLZ was 1.3-1000.0 ng mL-1 (R2 = 0.9991) and for LRP it was 3.6-800.0 ng mL-1 (R2 = 0.9993). Extraction recovery and the enrichment factor for CLZ were 95.4% and 343 and for LRP they were 74.3% and 263, respectively. Finally, the method developed was successfully applied for the simultaneous determination of CLZ and LRP in human plasma samples.

Development of a magnetic dispersive micro-solid-phase extraction method based on a deep eutectic solvent as a carrier for the rapid determination of meloxicam in biological samples.

In this study, an environmentally friendly magnetic dispersive micro solid-phase extraction was developed based on a deep eutectic solvent as a carrier and disperser of ferrofluids for the isolation and pre-concentration of meloxicam from biological samples. The extracted analyte was then analyzed by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The ferrofluid was prepared via a combination of silica-coated magnetic nanoparticles and an ethylene glycol/choline chloride deep eutectic solvent as a carrier. In this method, the rapid injection of the magnetic nanoparticles into the sample solution using a green carrier liquid increased the contact surface between the adsorbent and the target analyte which reduced the amount of the adsorbent and extraction time. A fractional factorial design was used for screening some effective parameters such as the amount of SiO2@Fe3O4, extraction time, pH of the sample solution, amount of the salt, volume of the desorption solvent, and desorption time. The effective parameters were then optimized by central composite design. Optimized extraction conditions were: amount of SiO2@Fe3O4 of 2 mg; extraction time of 1 min; pH of the sample solution of 4; volume of the desorption solvent of 200 µL; and desorption time of 2 min. Under the optimal conditions, wide linear ranges of 5-500 µg L-1 for water and 10-500 µg L-1 were obtained for urine and plasma samples with acceptable extraction recoveries above 89.2%. Limit of detections (LODs) were in the range of 1.5-3.0 µg L-1. The enrichment factors achieved were above 44.6 with relative standard deviations lower than 6.2%.

In situ growth of zeolitic imidazolate framework-8 on woven cotton yarn for the thin film microextraction of quercetin in human plasma and food samples.

This study explored the in-situ growth of zeolitic imidazolate framework-8 on woven cotton yarn for the first time. The applicability of highly flexible and natural cotton yarn-polypyrrole-layered double hydroxide-zeolitic imidazolate framework-8 composite (CY- PPy-LDH-ZIF8) was introduced for the extraction of quercetin in plasma and food samples. For increasing the contact area of the analyte and the prepared sorbent, the green substrate was woven and employed as the substrate for the construction of ZIF8. Extraction, separation, and determination of the analyte were performed by TFME-HPLC-UV. Due to the large surface area, the number of cages and unique porous structure of the zeolitic imidazolate framework-8 (ZIF8) as well as hydrogen bonding, ionic and π-π interactions between the analyte and the ZIF8, the prepared thin film showed a high affinity towards the target analyte. The affecting parameters on the extraction efficiency, including pH of the sample solution, extraction time, stirring rate, desorption time, and elution solvent volume were investigated and optimized through applying Box-Behnken Design (BBD). Under optimum conditions, calibration curves were found to be linear in the range of 0.2-200 µg L-1 with r2 > 0.9958. The limits of detection (based on S/N = 3), limits of quantification (based on S/N = 10), and intra-day, as well as inter-day RSDs, were lower than 0.21 µg L-1, 0.70 µg L-1 and 5.6%, respectively.

A banana peel/silicon glue coated stir bar for extraction of aspirin, diclofenac, ibuprofen and mefenamic acid followed by high performance liquid chromatography-UV detection.

In the current study, a green, cost-effective, and bio-degradable additive was used for the preparation of a highly efficient sorbent based on silicon glue. Here, a banana peel was pretreated and mixed with silicon glue. It was proved that the prepared banana peel-silicon glue bar is a reliable sorbent for stir bar sorptive extraction of nonsteroidal anti-inflammatory drugs (NSAIDs) including aspirin, diclofenac, ibuprofen and mefenamic acid in human urine and plasma. Compared to the lab-made sorbents, the prepared sorbent showed high extraction performance, high stability, and satisfactory reproducibility and involved easy preparation. In order to optimize the effective factors, different parameters such as (stirring rate, pH, extraction time, desorption time and elution solvent volume) were optimized using response surface methodology (RSM) through applying Central-Composite Design (CCD). Under the optimum conditions, the linear dynamic ranges of the target analytes were investigated in the range of 0.2-200 µg L-1 with r2 higher than 0.9929. Limits of detection (LODs) and limits of quantification (LOQs) of analytes were in the ranges of 0.04-0.5 and 0.15-1.65, respectively. The reproducibility of the method was also investigated by calculating the relative standard deviation. The RSD was measured to be lower than 4.9%. Bar-to-bar reproducibility at a 100 µg L-1 concentration level was also evaluated to be lower than 5.3% (n = 3). Also, each prepared film can be used up to 64 times without any reduction in extraction performance. Finally, the method was successfully applied for the determination of selected drugs in different biological fluids including urine and plasma samples. The calculated relative recovery in real sample analysis was higher than 90%.

Dimethyldioctadecylanimonium bentonite immobilized magnetic chitosan nanoparticles as an efficient adsorbent for vortex-assisted magnetic dispersive micro-solid-phase extraction of celecoxib from human breast milk, plasma and urine samples.

A polymer/layered silicate composite based on dimethyldioctadecylanimonium bentonite/chitosan magnetic nanoparticles was synthesized and characterized by field emission transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. The prepared nanocomposite was used to isolate and preconcentrate celecoxib from human breast milk, urine and plasma samples. In this method, dimethyldioctadecylanimonium bentonite increases the accessibility of binding sites and adsorption capacity by high microporosity and large surface area, that has been realized for the first time in a magnetic chitosan nanoparticle support. A fractional factorial design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box-Behnken design. Under the optimized conditions, the developed method exhibited wide linear ranges of 5-500 µg L-1 for plasma and urine and 10-500 µg L-1 for breast milk samples with satisfactory recoveries in the range of 96.7-99.0%. Limit of detection and quantification of celecoxib were in the ranges 0.3-3.2 and 0.99-10.56, respectively. The enrichment factors were obtained in the ranges 64.5-66.0, while precisions were <3.7%.

Hydrophobic borneol-based natural deep eutectic solvents as a green extraction media for air-assisted liquid-liquid micro-extraction of warfarin in biological samples.

In the present study, a new generation of water-immiscible natural deep eutectic solvents (DESs) was synthesized using borneol as a hydrogen-bonding acceptor and decanoic acid, oleic acid, and thymol as a hydrogen-bonding donor in different molar ratios. These green hydrophobic solvents which are chemically stable in aqueous solutions were used as extraction solvents for isolation and pre-concentration of warfarin in biological samples. In this method, fine droplets of DESs were dispersed into the sample solution by using the air-assisted liquid-liquid micro-extraction method to accelerate the cloudy emulsion system formation and increase the mass transfer of the analyte to the DES-rich phase. The borneol based deep eutectic solvent is a worthy generation of the extraction solvents in the ALLME method due to low-cost and less toxicity. A Plackett-Burman design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box-Behnken design (BBD). Optimized extraction conditions were pH of sample solution of 3.9, number of aspiration/dispersion cycles of 15, the volume of DES of 60 µL, and rate and time of centrifuge of 6000 rpm and 10 min, respectively. Under the optimized conditions, the developed NADES-ALLME method exhibited a wide linear range of 5-500 µg L - 1 for plasma and urine samples with satisfactory recoveries above 88.80%. Limit of detections (LODs) and Limit of quantifications (LOQs) of warfarin were in the ranges of 0.5-2.7 and 1.65-8.91, respectively. The enrichment factors were obtained in the range of 148-164 and precisions were lower than 5.87%. Finally, the proposed method was successfully employed for the analysis of warfarin in human urine and plasma samples.

Determination of Morin and Quercetin in Fruit Juice Samples using Air-Assisted Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet and HPLC-UV.

In this study, a rapid and efficient method has been used for the extraction and determination of morin and quercetin in fruit juice samples based on air-assisted liquid-liquid microextraction based on solidification of floating organic droplet and HPLC-UV. The effects of 7 important parameters on the extraction recovery were examined and were optimized by Plackett-Burman design and Central Composite design. According to the Plackett-Burman design results, ionic strength of the sample solutions, the aspiration/dispersion cycles, and the rate and time of centrifuge did not show significant effects on the extraction of morin and quercetin. The optimized conditions of extraction were as follows; the volume of the extraction solvent of 83.6 µL, pH of 4.34 for the sample, and 1-undecanol as extraction solvent. Under these conditions, the linear calibration curve was in the ranges of 1-1000 ng/mL and 0.5-1000 ng/mL for morin and quercetin, respectively, with the determination coefficient values above 0.99. The limit of detection of morin and quercetin was 0.3 and 0.2 ng/mL, respectively. The extraction recoveries for 10 ng/mL of morin and quercetin were 98.9% and 96.5%, respectively; while, relative standard deviations (n = 3) were lower than 3.2%.

Graphene Oxide/Polyethylene Glycol-Stick for Thin Film Microextraction of ß-Blockers from Human Oral Fluid by Liquid Chromatography-Tandem Mass Spectrometry.

A wooden stick coated with a novel graphene-based nanocomposite (Graphene oxide/polyethylene glycol (GO/PEG)) is introduced and investigated for its efficacy in solid phase microextraction techniques. The GO/PEG-stick was prepared and subsequently applied for the extraction of ß-blockers, acebutolol, and metoprolol in human oral fluid samples, which were subsequently detected by liquid chromatography tandem mass spectrometry (LC-MS/MS). Experimental parameters affecting the extraction protocol including sample pH, extraction time, desorption time, appropriate desorption solvent, and salt addition were optimized. Method validation for the detection from oral fluid samples was performed following FDA (Food and Drug Administration) guidelines on bioanalytical method validation. Calibration curves ranging from 5.0 to 2000 nmol L-1 for acebutolol and 25.0 to 2000 nmol L-1 for metoprolol were used. The values for the coefficient of determination (R2) were found to be 0.998 and 0.996 (n = 3) for acebutolol and metoprolol, respectively. The recovery of analytes during extraction was 80.0% for acebutolol and 62.0% for metoprolol, respectively. The limit of detections (LODs) were 1.25, 8.00 nmol L-1 for acebutolol and metoprolol and the lower limit of quantifications (LLOQ) were 5.00 nmol L-1 for acebutolol and 25.0 nmol L-1 for metoprolol. Validation experiments conducted with quality control (QC) samples demonstrated method accuracy between 80.0% to 97.0% for acebutolol and from 95.0% to 109.0% for metoprolol. The inter-day precision for QC samples ranged from 3.6% to 12.9% for acebutolol and 9.5% to 11.3% for metoprolol. Additionally, the GO/PEG-stick was demonstrated to be reusable, with the same stick observed to be viable for more than 10 extractions from oral fluid samples.

Modified magnetic chitosan nanoparticles based on mixed hemimicelle of sodium dodecyl sulfate for enhanced removal and trace determination of three organophosphorus pesticides from natural waters.

Mixed hemimicelle SDS-coated magnetic chitosan nanoparticles (MHMS-MCNPs) were utilized as an efficacious adsorbent for both removal and preconcentration of pesticides named diazinon, phosalone and chlorpyrifos. In this method, the formation of mixed hemimicelles made up of SDS on the surface of MCNPs leads to solubilization and the retention of target analytes by strong hydrophobic and electrostatic interactions, which has been realized for the first time in magnetic chitosan nanoparticles support. Different parameters affecting the adsorption of pesticides were optimized as rFemoval efficiency by response surface methodology and one variable at a time. Under the optimum condition, adsorption equilibrium data were fitted well to the Langmuir isotherm. Extraction recoveries for 5 ng mL-1 of diazinon, phosalone and chlorpyrifos were 99%, 98% and 96%, respectively; with relative standard deviations values were lower than 4.6% for five replications of extraction. Limit of detection obtained for mentioned pesticides were <0.09 ng mL-1. Eventually, MHMS-MCNPs were successfully applied for both removal and trace determination of pesticides in surface and ground environmental and waste water samples collected from various places in northern Iran.

Alcohol-based deep eutectic solvent as a carrier of SiO2 @Fe3 O4 for the development of magnetic dispersive micro-solid-phase extraction method: Application for the preconcentration and determination of morin in apple and grape juices, diluted and acidic extract of dried onion and green tea infusion samples.

In this study, a hydrophilic deep eutectic solvent was synthesized as a carrier and disperser of magnetic nanoparticles based on ferrofluid and used to develop the dispersive micro-solid-phase extraction method. Ethylene glycol/tetramethylammonium chloride deep eutectic solvent and SiO2 @Fe3 O4 were used to provide the highly stable ferrofluid with strong sorbing properties without any additional stabilizer, which was employed to extract and determine morin in apple and grape juices, diluted and acidic extract of dried onion, and green tea infusion samples. The dispersibility of SiO2 @Fe3 O4 and prevention of its aggregation in the sample solution were improved using the deep eutectic solvent-based ferrofluid. Also, it facilitated the fast injection of sorbent into the sample solution that led to an increase of the contact surface between the sorbent and analyte, and reduction of the extraction time and consumption of the sorbent. The important experimental parameters influencing the extraction efficiency of morin were examined. Under the optimal conditions, a linear calibration curve was obtained in the range of 3-500 µg/L with a determination coefficient of 0.9994. The limits of detection and quantification were of 0.91 and 2.98 µg/L, respectively. While an extraction recovery of 97.7% with relative standard deviation of 3.8% (interday) was obtained via three replicated measurements on a 30 µg/L of morin standard solution, the enrichment factor was 39.1. Finally, this method was successfully used to extract and preconcentrate morin in various samples, followed with their determination by high-performance liquid chromatography with ultraviolet detection.

Air assisted - vesicle based microextraction (AAVME) as a fast and green method for the extraction and determination of phenolic compounds in M. officinalis L samples.

In this research, a simple, rapid, and efficient air assisted - vesicle based microextraction (AAVME) approach was developed for the extraction of phenolic compounds and their analysis in different Melissa officinalis L. samples. The extraction method is based injection an aqueous mixture of CTAB and 5-methyl salicylic acid, into the hydroalcoholic plant extract in a conical test tube to form a cloudy solution. Suction and dispersion were then applied to accelerate the dispersion process. After centrifugation, the sediment phase was removed and injected into HPLC system. The optimized extraction conditions were as 450 µL of a mixture of CTAB and 5-methyl salicylic acid (3:5 mol ratios), 10.0 mL sample solution at pH 8.0 and 30 suction-dispersion cycles. Under these extraction conditions, the proposed method was able to provide a good linearity (R2 ≥ 0.9994) within the range of 0.5-2500.0 ng mL-1, low detection limits (0.1-0.5 ng mL-1), good extraction replicability (relative standard deviations below 3.5%, n = 7), and enrichment factors of 97-118. Finally, the developed method was successfully used for determining the mentioned analytes in Melissa officinalis samples. Recoveries for all compounds in real samples were between 82.5% and 91.8.

Application of non-ionic surfactant as a developed method for the enhancement of two-phase solvent bar microextraction for the simultaneous determination of three phthalate esters from water samples.

The extraction of phthalate esters (PEs) from aqueous matrices using two-phase solvent bar microextraction by organic micellar phase was investigated. A short hollow fiber immobilized with reverse micelles of Brij 35 surfactant in 1-octanol was served as the solvent bar for microextraction. Experimental results show that the extraction efficiency were much higher using two-phase solvent bar microextraction based on non-ionic surfactant than conventional two-phase solvent bar microextraction because of a positive effect of surfactant-containing extraction phase in promoting the partition process by non-ionic intermolecular forces such as polar and hydrophobicity interactions. The nature of the extraction solvent, type and concentration of non-ionic surfactant, extraction time, sample pH, temperature, stirring rate and ionic strength were the effecting parameters which optimized to obtain the highest extraction recovery. Analysis of recovered analytes was carried out with high performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). Under the optimum conditions, linearity was observed in the range of 1-800 ng mL-1 for dimethylphthalate (DMP) and 0.5-800 ng mL-1 for diethylphthalate (DEP) and di-n-butyl phthalate (DBP) with correlation determination values above 0.99 for them. The limits of detection and quantification were ranged from 0.012 to 0.03 ng mL-1 and 0.04-0.1 ng mL-1, respectively. The ranges of intra-day and inter-day RSD (n = 3) at 20 ng mL-1 of PEs were 1.8-2.1% and 2.1-2.6%, respectively. Results showed that developed method can be a very powerful, innovative and promising sample preparation technique in PEs analysis from environmental and drinking water samples.

Magnetic core micelles as a nanosorbent for the efficient removal and recovery of three organophosphorus pesticides from fruit juice and environmental water samples.

Sodium dodecyl sulfate coated amino-functionalized magnetic iron oxide nanoparticles were used as an efficient adsorbent for rapid removal and preconcentration of three important organophosphorus pesticides, chlorpyrifos, diazinon and phosalone, by ultrasound-assisted dispersive magnetic solid-phase microextraction. Fabrication of amino-functionalized magnetic nanoparticles was certified by characteristic analyses, including Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Affecting parameters on the removal efficiency were investigated and optimized through half-fractional factorial design and Doehlert design, respectively. The analysis of analytes was performed by high-performance liquid chromatography with ultraviolet detection. Under the optimum conditions, extraction recoveries for 20 ng/mL of organophosphorus pesticides were in the range of 84-97% with preconcentration factors in the range of 134-155. Replicating the experiment in above condition for five times gave the relative standard deviations <6%. The calibration curves showed high linearity in the range of 0.2-700 ng/mL and the limits of detection were in the range of 0.08-0.13 ng/mL. The proposed method was successfully applied for both removal and trace determination of these three organophosphorus pesticides in environmental water and fruit juice samples.

Ultrasound-assisted dispersive magnetic solid phase extraction based on amino-functionalized Fe3O4 adsorbent for recovery of clomipramine from human plasma and its determination by high performance liquid chromatography: Optimization by experimental design.

The applicability of Amino-functionalized Fe3O4 nanoparticles (NPs) as an effective adsorbent was developed for the extraction and determination of clomipramine (CLP) in plasma sample by ultrasound-assisted dispersive magnetic solid phase extraction (UADM-SPE) and high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. Fabrication of the Fe3O4@SiO2-NH2 magnetic nanoparticles confirmed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of different extraction parameters (i.e. pH of the sample solution, the amount of magnetic nanoparticles (MNPs), sample volume, temperature and sonication time) on the extraction recovery of CLP were investigated by response surface methodology through central composite design (CCD). The optimum condition is obtained when the affecting parameters are set to: pH of the sample solution=9, the amount of MNPs=37mg, sample volume=23mL, 25°C temperature and sonication time=1min. Under the optimum condition, extraction recovery was 90.6% with relative standard deviation of 3.5%, and enrichment factor of 117. The linear range for determination of CLP was 0.017-0.70mgL-1 with a determination coefficient (R2) of 0.999. Limit of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.0167mgL-1, respectively. The established UADM-SPE-HPLC-UV method was rapid, simple and efficient for determination of CLP in human plasma samples.

Optimization of multiwalled carbon nanotubes reinforced hollow-fiber solid-liquid-phase microextraction for the determination of polycyclic aromatic hydrocarbons in environmental water samples using experimental design.

A novel design of hollow-fiber liquid-phase microextraction containing multiwalled carbon nanotubes as a solid sorbent, which is immobilized in the pore and lumen of hollow fiber by the sol-gel technique, was developed for the pre-concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples. The proposed method utilized both solid- and liquid-phase microextraction media. Parameters that affect the extraction of polycyclic aromatic hydrocarbons were optimized in two successive steps as follows. Firstly, a methodology based on a quarter factorial design was used to choose the significant variables. Then, these significant factors were optimized utilizing central composite design. Under the optimized condition (extraction time = 25 min, amount of multiwalled carbon nanotubes = 78 mg, sample volume = 8 mL, and desorption time = 5 min), the calibration curves showed high linearity (R2  = 0.99) in the range of 0.01-500 ng/mL and the limits of detection were in the range of 0.007-1.47 ng/mL. The obtained extraction recoveries for 10 ng/mL of polycyclic aromatic hydrocarbons standard solution were in the range of 85-92%. Replicating the experiment under these conditions five times gave relative standard deviations lower than 6%. Finally, the method was successfully applied for pre-concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples.