Easy and fast synthesis of MnCo-LDH yolk-shell spheres porous composites applied electrospinning nanofibers highly effective for extracting triazole fungicides.

Today, the wide utilization of triazole fungicides due to environmental damage and its side effects has raised global concern. Thus, in this investigation, polyacrylonitrile/MnCo-layered double hydroxides nanofiber was synthesized and applied as an effective and novel adsorbent at thin-film solid-phase micro-extraction technique for the quick and concurrent extraction of five triazole fungicides in fruit and vegetable samples before quantitative analysis by high-performance liquid chromatography-ultraviolet. The incorporation of MnCo-layered double hydroxides with porous structure and abundant functional groups in a polymer medium improves the extraction efficiency of nanofibers owing to hydrogen bonding and π-π interactions formed between analytes and synthesized nano-adsorbent. Various important elements that affect the extraction efficiency of the intended analytes were optimized using a time-variable approach. Under the optimum conditions, the limit of detection and quantification range from 0.1 to 0.15 and 0.3-0.5 ng mL-1, respectively.

Development of electrospun nanofibers based on Poly (vinyl alcohol) for thin film solid-phase microextraction of antidepressant drugs in biological samples.

Today, antidepressants are widely used and it is important to determine their trace amounts due to harmful consequences. Here, a new nano sorbent was reported for the simultaneous extraction and determination of three types of antidepressant drugs (Clomipramine (CLO), Clozapine (CLZ), and Trimipramine (TRP) by the thin-film solid-phase micro-extraction (TFME-µSPE) method followed by the Gas Chromatography-flame ionization detector (GC-FID) analysis. So, the compound poly (vinyl alcohol) (PVA)/citric acid(CA)/ß-cyclodextrin/Bi2S3@g-C3N4 nano sorbent was constructed by electrospinning technique. Then, nano sorbent was studied to optimize the many parameters impacting the extraction performance. Electrospun nanofiber has a large surface area, high porosity, and homogeneous morphology with a uniform bead-free structure. In optimal conditions, the limits of detection and quantification were calculated to be 0.15-0.03 ng mL-1 and 0.5-0.1 ng mL-1, respectively. The dynamic linear range (DLR) was in the range of 0.1 to 1000 ng mL-1 for CLO and CLZ, and 0.5 to 1000 ng mL-1 for TRP with correlation coefficients (R2) of 0.999. The relative standard deviations (RSDs) were achieved in the range of 4.9-6.8% (intra-day, n = 4) and 5.4-7.9% (inter-day, n = 3) in the period of 3 days. Finally, the capability of the method was evaluated to simultaneously measure trace amounts of antidepressants aqueous sample with desirable extraction efficiency (78 to 95%).

Curcumin-Melamine For Solid-Phase Microextraction of Volatile Organic Compounds from Aqueous Samples.

The hybrid coating of curcumin and melamine was prepared by a simple electrochemical method. Some physical and chemical properties of the fiber were studied by several methods such as FT-IR, scanning electron microscopy and X-ray fluorescence spectroscopy. The fiber was stable at the inlet of a gas chromatograph at temperatures up to 280°C. The fiber has been used for the extraction of ethylbenzene, toluene and xylenes (ETX). Some parameters of headspace solid-phase microextraction, including extraction time, temperature and salt amount, were optimized. Under the optimized situation, the detection limits were 0.15-0.21 µg L -1 and the linear ranges were within the range of 0.5-1,000 µg L-1 (r2 ≥ 0.99). The intra-day and inter-day relative standard deviations were 10.2-13.7 and 13.0-15.6%, respectively, at a concentration level of 10 µg L-1 from each compound by applying a single fiber. The method was used to successfully analyze wastewater and pool water samples.

Synthesis of NiGa2S4-rGO on nickel foam as advanced electrode for flexible solid-state supercapacitor with superior energy density.

Pseudocapacitive electrode materials employed in supercapacitors may bring in high energy density (ED) and specific capacitance (Csc), which are critical for their practical applications. Accordingly, logical design of advanced electrode materials is highly demanded to progress high-performance supercapacitors. Here, for the first time, we suggest a straightforward route for the synthesis of NiGa2S4-rGO as an advanced cathode material supported on nickel foam (NF) for employed in flexible solid-state asymmetric supercapacitors (FSASCs). Due to an abundant ratio of active sites and large surface area of the NiGa2S4-rGO advanced material, the as-prepared NiGa2S4-rGO/NF electrode illustrates considerable electrochemical properties including remarkable specific capacitance (Csc) of 2124.34 F g-1 with excellent rate capability of 73%, and exceptional durability, which are better than NiGa2S4/NF and previously reported transition metal sulfides (TMSs). Furthermore, for the first time a pseudocapacitive advanced anode material of FeSe2-rGO have been successfully fabricated on a nickel foam (NF) substrate by a facile strategy. Element Selenium as the favorable element was offered into the Fe for enhancement and adjustment of the anode material electrochemical performance. The FeSe2-rGO/NF advanced anode electrode presents satisfactory electrochemical properties containing an exceptional specific capacitance (Csc) of 432.40 F g-1, significant rate performance of 57.84% and superior durability, which are better than FeSe2/NF electrode and previously studied Fe-based anode material. Considering the remarkable electrochemical performance of the as-prepared pseudocapacitive advanced electrode materials, a FSASC based on the NiGa2S4-rGO/NF as the cathode electrode and FeSe2-rGO/NF as the anode electrode was assembled. The FSASC device delivers superior Csc of 341.20 F g-1, outstanding energy density (ED) of 121.31 W h kg-1, remarkable cycle stability (only 7.30% damage after 5000 charge/discharge (CD) cycles).

Highly efficient electrochemical determination of propylthiouracil in urine samples after selective electromembrane extraction by copper nanoparticles-decorated hollow fibers.

In this work, a novel, inexpensive and fast strategy was described for selective and effective extraction and determination of propylthiouracil (PTU) with a high polarity (log P = 1.2) based on electromembrane extraction (EME) followed by differential pulse voltammetry (DPV). For this purpose, copper nanoparticles (CuNPs)-decorated hollow fiber was used as the selective membrane for EME of PTU in urine samples. The influential parameters on extraction such as extraction solvent, pH, agitation speed, applied potential and extraction time were systematically investigated. In optimized conditions, acceptable linearity was attained between 0.05 and 5 µg mL-1 (R2 value = 0.9994); moreover, superb enrichment factor (200) and repeatability (RSD%, n = 4, 5.7%) for 0.1 µg mL-1 of PTU solution were in desirable range. In addition, extraction recovery of 80.0% was achieved in this condition and the limit of detection (S/N ratio of 3:1) was 0.02 µg mL-1. Finally, the proposed method was successfully applied to determine PTU concentration in urine samples.

Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples.

In this research, for first time selective separation and determination of Azathioprine is demonstrated using molecularly imprinted polymer as the solid-phase extraction adsorbent, measured by spectrophotometry at λmax 286nm. The selective molecularly imprinted polymer was produced using Azathioprine and methacrylic acid as a template molecule and monomer, respectively. A molecularly imprinted solid-phase extraction procedure was performed in column for the analyte from pharmaceutical and serum samples. The synthesized polymers were characterized by infrared spectroscopy (IR), field emission scanning electron microscopy (FESEM). In order to investigate the effect of independent variables on the extraction efficiency, the response surface methodology (RSM) based on Box-Behnken design (BBD) was employed. The analytical parameters such as precision, accuracy and linear working range were also determined in optimal experimental conditions and the proposed method was applied to analysis of Azathioprine. The linear dynamic range and limits of detection were 2.5-0.01 and 0.008mgL-1 respectively. The recoveries for analyte were higher than 95% and relative standard deviation values were found to be in the range of 0.83-4.15%. This method was successfully applied for the determination of Azathioprine in biological and pharmaceutical samples.

Selective and sensitive speciation analysis of Cr(VI) and Cr(III), at sub-µgL-1 levels in water samples by electrothermal atomic absorption spectrometry after electromembrane extraction.

In this work, electromembrane extraction in combination with electrothermal atomic absorption spectrometry (ET-AAS) was investigated for speciation, preconcentration and quantification of Cr(VI) and Cr(III) in water samples through the selective complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) as a complexing agent. DPC reduces Cr(VI) to Cr(III) ions and then Cr(III) species are extracted based on electrokinetic migration of their cationic complex (Cr(III)-DPC) toward the negative electrode placed in the hollow fiber. Also, once oxidized to Cr(VI), Cr(III) ions in initial sample were determined by this procedure. The influence of extraction parameters such as pH, type of organic solvent, chelating agent concentration, stirring rate, extraction time and applied voltage were evaluated following a one-at-a-time optimization approach. Under optimized conditions, the extracted analyte was quantified by ETAAS, with an acceptable linearity in the range of 0.05-5ngmL-1 (R2 value=0.996), and a repeatability (%RSD) between 3.7% and 12.2% (n=4) for 5.0 and 1.0ngmL-1 of Cr(VI), respectively. Also, we obtained an enrichment factor of 110 that corresponded to the recovery of 66%. The detection limit (S/N ratio of 3:1) was 0.02ngmL-1. Finally, this new method was successfully employed to determine Cr(III) and Cr(VI) species in real water samples.

An efficient approach to selective electromembrane extraction of naproxen by means of molecularly imprinted polymer-coated multi-walled carbon nanotubes-reinforced hollow fibers.

In this work, a novel microextraction technique using molecularly imprinted polymer-coated multi-walled carbon nanotubes (MIP-MWCNTs) in electromembrane extraction (EME) procedure is described. The method in combination with HPLC-UV was utilized to determine naproxen, as an acidic model drug, in urine, plasma and wastewater samples. For this purpose, MIP-MWCNTs were placed in the pores of polypropylene hollow fiber. The MIP-MWCNTs-EME method has the advantages of high selectivity and cleanup of MIP along with high enrichment ability of the EME in a single step extraction. Continuing with the research, optimization of the factors affecting the migration of naproxen from sample solutions to MIP-MWCNTs sites and then into the lumen of hollow fiber was explored. Under the optimized conditions, the limit of detection (LOD) of the developed method was calculated to be 0.3µgL-1. All relative standard deviations (RSDs) were lower than 3%. Linearity of the method was obtained within the range of 1-1000µgL-1 with the coefficient of determination (r2) being higher than 0.999. Under the optimized conditions, an extraction recovery of 66% was obtained, which corresponded to a preconcentration factor of 88. Finally, the developed method was satisfactorily used to determine naproxen in urine, plasma and wastewater samples.

Sonoelectrochemical Synthesis of Nano Zinc (II) Complexes with 9-Anthracenecarboxylic Acid: Effect of Current Density and Study of their Photophysical Properties.

A new zinc complex, [Zn (9-AC)2] (1) (9-AC = 9-anthracenecarboxylic acid), was prepared via conventional electrochemical method in a fast and facile process and fully characterized by 1H NMR, 13C NMR, IR spectroscopy and elemental analysis. The nano structures of the same compound were successfully produced by a facile and environment-friendly sonoelectrochemical route at different current densities (0.5, 1.2, 1.8, 2.5 and 3.5 mA/cm2). The new nano-structure particles were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Thermal stability of single crystal and nano-size samples of the prepared compound was studied by thermogravimetric and differential thermal analysis. The comparison of the effect of current density without and with ultrasonic irradiation on particle size has been investigated in convectional electrochemical and sonoelectrochemical method respectively. The results showed that using ultrasonic irradiation with increasing the current density lead to decrease the particle sizes unlike conventional electrochemical method. In other words, when the current density increase from 0.5 to 3.5 mA/cm2, in sonoelectrochemical method, the particle sizes decrease from 100 to 48 nm while, in convectional electrochemical method, the particle sizes increase from 400 to 1200 nm and possible explanation offered. Photoluminescence properties of the nano-structured and crystalline bulk of the prepared complex at room temperature in the solid state have been investigated in detail. The results indicate that the size of the complex particles has an important effect on their optical properties.

Impedometric monitoring of the behavior of the supported liquid membrane in electromembrane extraction systems: An insight into the origin of optimized experimental parameters.

Electromembrane extraction (EME) was carried out using a novel instrumentation capable of impedometric monitoring of the system during the extraction. This instrumentation involves a classical two-electrode assembly fed by two time-resolved potential functions, the first for the extraction of analyte and the second for obtaining the impedance information. The impedometric analysis of the system was achieved by Laplace transformation of the current recorded during the extraction. It has been shown that the obtained impedance information can be converted to very useful knowledge about time dependence of double layer capacitance, kinetics of analyte depletion, total permeability of the SLM and the effect of experimental parameters on system behavior. It has also been shown that the impedance analysis is a powerful tool for the estimation of optimum experimental parameters without determination of analyte in the acceptor phase.

Highly selective determination of amitriptyline using Nafion-AuNPs@branched polyethyleneimine-derived carbon hollow spheres in pharmaceutical drugs and biological fluids.

In this paper, AuNPs@Polyethyleneimine-derived carbon hollow spheres were synthesized by a versatile and facile method in three steps and successfully developed and validated as Amitriptyline sensor using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV) methods. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), x-ray photo-electron spectrum (XPS), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). The obtained negatively charged modified electrode was highly selective to Amitriptyline and it was shown a wide linear range from 0.1 to 700µmolL(-1), with a lower detection limit of 0.034µmolL(-1) (n=5, S/N=3), revealing the high-sensitivity properties. The modified electrode is used to achieve the real-time quantitative detection of AMT for biological applications, and satisfactory results are obtained. Due to the advantages of the sensor, its selectivity, sensitivity and stability, it will have a bright future in the field of medical diagnosis.

Surfactant assisted pulsed two-phase electromembrane extraction followed by GC analysis for quantification of basic drugs in biological samples.

In this work, a simple and efficient surfactant assisted pulsed two-phase electromembrane extraction (SA-PEME) procedure combined with gas chromatography (GC) has been developed for the determination of alfentanil, sufentanil and methadone in various samples. It has been found that the addition of anionic surfactant causes the accumulation of the cationic analytes at the SLM/solution interface resulting in an easier transfer of the analytes into the organic phase. The method was accomplished with 1-octanol as the acceptor phase and supported liquid membrane (SLM) by means of an 80 V pulsed electrical driving force and the extraction time of 20 min. The model analytes were extracted from 3.0 mL sample solution (pH 4.0) containing 0.02% w/v surfactant (sodium dodecyl sulfate). The duty cycle of 92% and frequency of 0.357 Hz gave the best performance. Extraction recoveries in the range of 70.5-95.2% and satisfactory repeatability (7.6

Electronic simulation of the supported liquid membrane in electromembrane extraction systems: Improvement of the extraction by precise periodical reversing of the field polarity.

In order to understand the limitations of electromebrane extraction procedure better, a simple equivalent circuit has been proposed for a supported liquid membrane consisting of a resistor and a low leakage capacitor in series. To verify the equivalent circuit, it was subjected to a simulated periodical polarity changing potential and the resulting time variation of the current was compared with that of a real electromembrane extraction system. The results showed a good agreement between the simulated current patterns and those of the real ones. In order to investigate the impact of various limiting factors, the corresponding values of the equivalent circuit were estimated for a real electromembrane extraction system and were attributed to the physical parameters of the extraction system. A dual charge transfer mechanism was proposed for electromembrane extraction by combining general migration equation and fundamental aspects derived from the simulation. Dual mechanism comprises a current dependent contribution of analyte in total current and could support the possibility of an improvement in performance of an electromembrane extraction by application of an asymmetric polarity changing potential. The optimization of frequency and duty cycle of the asymmetric polarity exchanging potential resulted in a higher recovery (2.17 times greater) in comparison with the conventional electromebrane extraction. The simulation also provided more quantitative approaches toward the investigation of the mechanism of extraction and contribution of different limiting factors in electromembrane extraction. Results showed that the buildup of the double layer is the main limiting factor and the Joule heating has lesser impact on the performance of an electromebrane extraction system.

Solid-phase microextraction of phthalate esters by a new coating based on a thermally stable polypyrrole/graphene oxide composite.

A novel polypyrole/graphene oxide coating was made by the electrochemical polymerization of pyrrole in the presence of sodium dodecyl sulfate and graphene oxide on a platinum wire. The prepared fiber has shown a good thermal stability up to 300°C. The fiber was applied to the direct solid-phase microextraction and gas chromatographic analysis of four phthalate esters. The effect of four parameters on gas chromatography peak area including extraction temperature, extraction time, injection temperature, and ionic strength were investigated. Under the optimized conditions, the detection limits were between 0.042 and 0.26 µg/L. The intraday and interday relative standard deviations obtained at 55 µg/L, using a single fiber, were 8.2-16% and 17.3-25.6%, respectively. The method was successfully applied to the analysis of phthalate esters in two real samples of boiling water in cheap disposable clear plastic drinking cups showing recoveries from 83 to 120%.

Solvent selection in ultrasonic-assisted emulsification microextraction: Comparison between high- and low-density solvents by means of novel type of extraction vessel.

There are numerous published reports about dispersive liquid phase microextraction of the wide range of substances, however, till now no broadly accepted systematic and purpose oriented selection of extraction solvent has been proposed. Most works deal with the optimization of available solvents without adequate pre-consideration of properness. In this study, it is tried to compare the performances of low- and high-density solvents at the same conditions by means of novel type of extraction vessel with head and bottom conical shape. Extraction efficiencies of seven basic pharmaceutical compounds using eighteen common organic solvents were studied in this work. It was much easier to work with high-density solvents and they mostly showed better performances. This work shows that although exact predicting the performance of the solvents is multifaceted case but the pre-consideration of initial selection of solvents with attention to the physiochemical properties of the desired analytes is feasible and promising. Finally, the practicality of the method for extraction from urine and plasma samples was investigated.

Application of a new fiber coating based on electrochemically reduced graphene oxide for the cold-fiber headspace solid-phase microextraction of tricyclic antidepressants.

A new fiber based on the electrochemical reduction of graphene oxide was prepared on a copper wire for solid-phase microextraction (SPME) applications. The prepared fiber was used for the SPME and gas chromatographic analysis of tricyclic antidepressants (TCADs), including amitriptyline, trimipramine, and clomipramine. The feasibility of direct-immersion and headspace modes of SPME for the determination of TCADs was studied. The effects of four parameters including pH, salt content, extraction temperature with and without cooling the fiber, and extraction time were investigated. The comparison showed that headspace cold fiber SPME results in the best outcome for the extraction of TCADs. Under the optimized conditions of this mode, the calibration curves were linear between 2.0 and 500 ng/mL and the detection limits were between 0.30 and 0.53 ng/mL. The intraday and interday RSDs obtained at 20 ng/mL (n = 5), using a single fiber, were 5.5-9.0 and 7.5-9.8, respectively. The fiber to fiber repeatability (n = 4), expressed as the RSD, was between 12.8 and 13.2% at a 20 ng/mL concentration level. The method was successfully applied to the analysis of TCADs in plasma samples showing recoveries from 73 to 96%.

A new platform for sensing urinary morphine based on carrier assisted electromembrane extraction followed by adsorptive stripping voltammetric detection on screen-printed electrode.

Electromembrane extraction (EME) coupled with electrochemical detection on screen-printed carbon electrode has been developed for the quantification of morphine in urine samples. Charged morphine molecules were extracted from an aqueous sample by applying an electrical potential through a thin supported liquid membrane (SLM) into an acidic aqueous acceptor solution (20 µL) placed inside the lumen of a hollow fiber. Then, the acceptor solution was mixed with 20 µL of NaOH solution (0.1 M) and analyzed using screen printed electrochemical strip. Differential pulse voltammetry (DPV) peak current at 0.18 V was selected as the signal and the influences of experimental parameters were investigated and optimized using Box-behnken design and also one-variable-at-a-time methodology as follows: adsorptive accumulation time, 40 s; SLM, 2-nitrophenyl octyl ether+10% tris-(2-ethylhexyl) phosphate+10% di-(2-ethylhexyl) phosphate; pH of the sample solution, 6.0; pH of the acceptor solution, 1.0; EME time, 24 min; EME potential, 90 V and stirring rate, 1000 rpm. The calibration curve which was plotted by the variation of DPV currents as a function of morphine concentration was linear within the range of 0.005-2.0 µg mL(-1). The limit of detection and the limit of quantification were 0.0015 (S/N=3) and 0.005 µg mL(-1), respectively. Finally, the proposed method was able to determine morphine simply and effectively at concentration levels encountered in toxicology and doping.

Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography.

This study proposes the dual electromembrane extraction followed by high performance liquid chromatography for selective separation-preconcentration of Cr(VI) and Cr(III) in different environmental samples. The method was based on the electrokinetic migration of chromium species toward the electrodes with opposite charge into the two different hollow fibers. The extractant was then complexed with ammonium pyrrolidinedithiocarbamate for HPLC analysis. The effects of analytical parameters including pH, type of organic solvent, sample volume, stirring rate, time of extraction and applied voltage were investigated. The results showed that Cr(III) and Cr(VI) could be simultaneously extracted into the two different hollow fibers. Under optimized conditions, the analytes were quantified by HPLC instrument, with acceptable linearity ranging from 20 to 500 µg L(-1) (R(2) values≥0.9979), and repeatability (RSD) ranging between 9.8% and 13.7% (n=5). Also, preconcentration factors of 21.8-33 that corresponded to recoveries ranging from 31.1% to 47.2% were achieved for Cr(III) and Cr(VI), respectively. The estimated detection limits (S/N ratio of 3:1) were less than 5.4 µg L(-1). Finally, the proposed method was successfully applied to determine Cr(III) and Cr(VI) species in some real water samples.

A selective electromembrane extraction of uranium (VI) prior to its fluorometric determination in water.

A novel method for the selective electromembrane extraction (EME) of U(6+) prior to fluorometric determination has been proposed. The effect of extraction conditions including supported liquid membrane (SLM) composition, extraction time and extraction voltage were investigated. An SLM composition of 1% di-2-ethyl hexyl phosphonic acid in nitrophenyl octyl ether (NPOE) showed good selectivity, recovery and enrichment factor. The best performance was achieved at an extraction potential of 80 volts and an extraction time of 14 minutes Under the optimized conditions, a linear range from 1 to 1000 ng mL(-1) and LOD of 0.1 ng mL(-1) were obtained for the determination of U(6+). The EME method showed good performance in sample cleanup and the reduction of the interfering effects of Mn(2+), Zn(2+), Cd(2+), Ni(2+), Fe(3+), Co(2+), Cu(2+), Cl(-) and PO4(3-) ions during fluorometric determination of uranium in real water samples. The recoveries above 54% and enrichment factors above 64.7 were obtained by the proposed method for real sample analysis.

Electro-assisted solid-phase microextraction based on poly(3,4-ethylenedioxythiophen) combined with GC for the quantification of tricyclic antidepressants.

In this study, a platinum wire coated with poly(3,4-ethylenedioxythiophen) was used as an electro-assisted solid-phase microextraction fiber for the quantification of tricyclic antidepressant drugs in biological samples by coupling to GC employing a flame ionization detector. In this study, an electric field increased the extraction rate and recovery. The fiber used as a solid phase was synthesized by the electropolymerization of 3,4-ethylenedioxythiophen monomers onto a platinum wire. The ability of this fiber to extract imipramine, desipramine, and clomipramine by using the electro-assisted solid-phase microextraction technique was evaluated. The effect of various parameters that influence the extraction efficiency, which include solution temperature, extraction time, stirring rate, ionic strength, time and temperature of desorption, and thickness of the fiber, was optimized. Under optimized conditions, the linear ranges and regression coefficients of calibration curves were in the range of 0.5-250 and 0.990-0.998 ng/mL, respectively. Detection limits were in the range of 0.15-0.45 ng/mL. Finally, this method was applied to the determination of drugs in urine and wastewater samples and recoveries were 4.8-108.9%.