Molecularly imprinted polypyrrole@CuO nanocomposite as an in-tube solid-phase microextraction coating for selective extraction of carbamazepine from biological samples.

A nanocomposite of molecularly imprinted polypyrrole on copper oxide (MIP@CuO) was introduced as a new coating for in-tube solid-phase microextraction (IT-SPME). The method coupled with HPLC-UV was successfully applied for analysis of carbamazepine (anticonvulsant and bipolar disorder medication) in biological samples. First, in order to increase the surface area and stability of the coating, copper oxide (CuO) nanosheets were synthesized on the inner surface of a copper tube using a chemical method. Then, molecularly imprinted polypyrrole coating (using carbamazepine as a template) was deposited on CuO by a facile in-situ electrodeposition method. According to the results, The MIP@CuO coating shows long life time, enhanced extraction efficiency, and good clean-up, for pre-concentration and determination of carbamazepine in biological samples. The synthesized adsorbent also showed high selectivity to carbamazepine compared to other drugs with similar structure. Important factors affecting the extraction efficiency of the analyte in the in-tube SPME method, such as salt concentration, extraction and desorption times, flowrates of the sample solution, and eluent, were optimized. Under optimal conditions, the method showed good linearity for carbamazepine in the range of 0.05-500 µg L-1, 0.10-500 µg L-1, and 0.10-500 µg L-1 in water, urine, and plasma samples, respectively, with coefficients of determination better than 0.996. The limits of detection were in the range of 0.01-0.05 µg L-1 in different matrices. The intra- and inter-assay precisions (RSD%, n = 3) were in the range of 6.7-8.1 % and 7.1-9.5 %, respectively.

Application of HKUST-1 metal-organic framework as coating for headspace solid-phase microextraction of some addictive drugs.

In the present study, a copper-based metal-organic framework (HKUST-1) was used first time for preconcentration trace amounts of addictive drugs in biological samples. HKUST-1 was synthesized and coated onto the surface of stainless steel wire. The prepared coating was used in headspace solid-phase microextraction method coupled with gas chromatography-mass spectrometry for preconcentration and determination of some addictive drugs in biological fluids. Prepared coating shows good extraction efficiency due to large surface area, and π-π stacking interaction with selected analytes. Under optimum conditions, the method was validated with a reasonable determination coefficient (R2  > 0.9961) and suitable linear dynamic range (0.5-1000 µg L-1 ). Also, the limits of detections were obtained in the range of 0.1-0.4, 0.2-0.6, and 0.4-0.7 µg L-1 for water, urine, and plasma samples, respectively. The limits of quantification of present method were obtained in the range 0.5-1.3, 0.7-1.5, and 1.0-1.9 µg L-1 in water, urine, and plasma samples, respectively. The intra-day and inter-dye single fiber and fiber to fiber relative standard deviations were observed in the range 3.0-13.9% and 3.5-12.3%, respectively. Finally, the present method was applied for the determination of the drugs in biological samples.

Applications of porous frameworks in solid-phase microextraction.

Porous frameworks are a term of attracting solid materials assembled by interconnection of molecules and ions. These trendy materials due to high chemical and thermal stability, well-defined pore size and structure, and high effective surface area gained attention to employ as extraction phase in sample pretreatment methods before analytical analysis. Solid-phase microextraction is an important subclass of sample preparation technique that up to now different configurations of this method have been introduced to get adaptable with different environments and analytical instruments. In this review, theoretical aspect and different modes of solid-phase microextraction method are investigated. Different classes of porous frameworks and their applications as extraction phase in the proposed microextraction method are evaluated. Types and features of supporting substrates and coating procedures of porous frameworks on them are reviewed. At the end, the prospective and the challenges ahead in this field are discussed.

Synthesis of an organic-inorganic hybrid absorbent for in-tube solid-phase microextraction of bisphenol A.

This research is an application of fiber-in-tube solid-phase microextraction followed by high-performance liquid chromatography with UV detection for the extraction and determination of trace amounts of bisphenol A. Nanomagnetic Fe3 O4 was formed on the surface of polypropylene porous hollow fibers to increase the surface area and then it was coated with polystyrene. The introduction of polystyrene improves the surface hydrophobicity and is an appropriate extractive phase because it is highly stable in aquatic media. The extraction was carried out in a short capillary packed longitudinally with the fine fibers as the extraction medium. Extraction conditions, including extraction and desorption flow rates, extraction time, pH, and ionic strength of the sample solution, were investigated and optimized. Under optimal conditions, the limit of detection was 0.01 µg/L. This method showed good linearity for bisphenol A in the range of 0.033-1000 µg/L, with the coefficient of determination of 0.9984. The inter- and intraday precisions (RSD%, n = 3) were 7.9 and 6.3%, respectively. Finally, the method was applied to analysis of the analyte in thermal papers, disposable plastic cups, and soft drink bottles.

Covalent organic framework and montomorillonite nanocomposite as advanced adsorbent: synthesis, characterization, and application in simultaneous adsorption of cationic and anionic dyes.

In this work, Schiff base network-1 (SNW-1), as a new generation of covalent organic frameworks (COFs), was synthesized and modified by fabrication of a composite with clay mineral montomorillonite (Mt). It was used for simultaneous removal of anionic and cationic dyes from aqueous solutions. The fabricated composite was characterized successfully with various techniques. Tartrazine (TT) and methylene blue (MB) were selected as model anionic and cationic dyes, respectively. The effects of the percentage of each component in the composite, initial pH, and initial dye concentration were evaluated on the adsorption capacity. Adsorption reaction models and adsorption diffusion models were used to study the kinetic process of adsorption. Adsorption of both dyes reached equilibrium after 40 min. The obtained results were fitted to Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) models to predict the isotherms of adsorption. Under optimum conditions for removal of each dye with the composite, the maximum adsorption capacity of 519.2 and 602.7 mg g-1 were obtained for TT and MB, respectively. The used SNW-1/Mt composite could be regenerated by salty methanol. The high adsorption capacity and excellent reusability make SNW-1/Mt composite attractive for the simultaneous removal of anionic and cationic dyes from aqueous solutions.

An electrodeposited terephthalic acid-layered double hydroxide (Cu-Cr) nanosheet coating for in-tube solid-phase microextraction of phthalate esters.

A CuCr-layered double hydroxide nanosheet intercalated with terephthalic acid (TPA/LDH) was introduced as a coating for the in-tube solid phase microextraction (IT-SPME). The coating was placed on the inner surface of a stainless steel tube by using two-electrode electrodeposition. The sorbent was characterized by X-ray diffraction, scanning electronic microscopy, and Fourier transform infrared spectroscopy. The TPA/LDH coating, compared to a nitrate-LDH coating, exhibits enhanced extraction efficiency, long lifetime, good mechanical stability, and a large specific surface. The method was used for the extraction, preconcentration, and subsequent HPLC-based determination of dimethyl phthalate (DMP), dibutyl phthalate (DBP), diallyl phthalate (DAP), and diethylhexyl phthalate (DEHP). The effects of pH value of the solution, salt concentration, extraction and desorption conditions, and the effect of the alcohol content of the solution on the extraction efficiency were optimized. Under optimal conditions, the response is linear in the 0.05 to 1000 µg L-1 ester concentration range, and the limits of detection (at S/N = 3) range between 0.01 to 0.1 µg L-1. The inter- and intra-assay precisions (RSD%, for n = 3) range from 3.8 to 6.8% and from 3.5 to 5.7%, respectively. The method was successfully applied to the determination of four phthalate esters in different beverage samples. Graphical abstractA CuCr-layered double hydroxide nanosheet intercalated with terephthalic acid was used as a coating for in-tube solid phase microextraction of some phthalate esters from beverage samples.

Developing a novel packed in-tube solid-phase extraction method for determination ∆ 9-tetrahydrocannabinol in biological samples and cannabis leaves.

A novel plate-like nano-sorbent based on copper/cobalt/chromium layered double hydroxide was synthesized by a simple coprecipitation method. The synthesized nanoparticels were introduced into a stainless steel cartridge using a dry packing method. Then, the packed cartridge was introduced as a novel on-line "packed in-tube" configuration and followed by high performance liquid chromatography for the determination of trace amounts of ∆ 9-tetrahydrocannabinol from biological samples and cannabis leaves. The as-prepared sorbent exhibited long lifetime, good chemical stability, and high anion-exchange capacity. Several important factors affecting the extraction efficiency, such as extraction and desorption times, pH of the sample solution and flow rates of the sample and eluent solutions, were investigated and optimized. Under optimized conditions, this method showed good linearity for ∆ 9-tetrahydrocannabinol in the ranges of 0.09-500, 0.3-500, and 0.4-500 µg/L with coefficients of determination of 0.9999, 0.9991, and 0.9994 in water, serum and plasma samples, respectively. The inter- and intra-assay precisions (n = 3) were respectively in the ranges of 1.8-4.6% and 1.9-4.0% at three concentration levels of 10, 50, and 100 µg/L. The limits of detection were also in the range of 0.02-0.1 µg/L.

Synthesis and characterization of a novel biocompatible pseudo-hexagonal NaCa-layered double metal hydroxides for smart pH-responsive drug release of dacarbazine and enhanced anticancer activity in malignant melanoma.

Layered metal hydroxides have exhibited remarkable benefits in drug delivery, days or even weeks of continuous drug release with improved bioavailability and minimized adverse effects. Here, we report synthesis of a new M+ (Na+) and M2+ (Ca2+) layered double metal hydroxide-based phases with the general formula of [Na0.2Ca0.8(OH)1.4] (NO3)0.4, and 3D pseudo-hexagonal morphology. NaCa layered double metal hydroxide (NaCa-LDH), which is biodegradable, biocompatible, and pH-sensitive, could have broad applicability in drug release and other biomedical applications. Dacarbazine (DAC) is one of the most commonly used chemotherapy drugs for treating various cancers. However, its poor water solubility, short half-life in blood circulation, low response rate and high side effects limit its application. This study aimed to increase its half-life and anticancer activity; minimize its side effects; and prolong its drug release by intercalating of DAC in biodegradable NaCa-LDH (DAC-LDH). Results from the intercalation process show that NaCa-LDH is able to intercalate DAC with a simple procedure and with a good drug loading (38% w/w) through a one pot reaction. The DAC shows a sustained and pH-sensitive release, and the release rate of DAC from DAC-LDH at pH 7.4 is remarkably lower than that at pH 6.0 due to its different release mechanisms. In the latter case, the release was not complete at 24 h. We show that DAC-LDH anticancer efficacy on malignant (A-375) melanoma and breast cancer (MCF-7) cell lines is higher than that of free DAC. These nanoparticles may open a significant way toward the development of a pH-sensitive drug release system that minimizes drug side effect for a wide range of applications.

One-step synthesis of Fe3PtPd(OH)2[Picolinic acid]8(H2O)4 hybrid nanorods: efficient and stable electrocatalyst for oxygen reduction reaction in alkaline solution.

Design and synthesis of effective electrocatalysts for oxygen reduction reaction in alkaline environments is critical to reduce energy losses in alkaline fuel cells. We have systematically evaluated new approaches for reducing the Pt content while retaining the activity of a Pt-based catalyst with hydrolytic phases containing hydroxide moieties in addition to metal ions and ligands. We report for the first time architectured organic-inorganic hybrid nanorod catalyst, which is fabricated by solvothermal reaction of K2MCl4 (M = Pd, Pt) with picolinic acid (PA) (chelating agent) in the presence of FeCl2. Excess base produces isostructural coordination M-PA complex to Fe-OH chains. A generic formula can be written as Fe3PtPd(OH)2[PA]8(H2O)4. The electrocatalytic activities of the hybrid nanorods are explored for oxygen reduction reaction (ORR) in alkaline medium. The onset potential of ORR is significantly reduced with a positive shift of about 109 mV and twice the reduction current density is observed in comparison with Pt/C with the same mass loading. We believe that this work may lead towards the development of heterodoped organic- inorganic hybrid materials with greatly enhanced activity and durability for applications in catalysis and energy conversion.

Simultaneous determination of steroid drugs in the ointment via magnetic solid phase extraction followed by HPLC-UV.

The copper-coated iron oxide nanoparticles with core-shell were produced by deposition of a Cu shell on Fe3O4 NPs through reduction of Cu2+ ions in solution using NaBH4. Subsequently, the organosulfur compound, bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid (b-TMP-DTPA), was used to form self-assembled monolayer in order to modify sorbent's surface via covalent bonding between Cu and thiol (-SH) terminal groups. The prepared magnetic nanoparticles were characterized by using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and thermo gravimetric analysis (TGA). Then, the application of this new sorbent was investigated to extract the steroid drugs in ointment samples with the aid of ultrasound. An external magnetic field was applied to collect the magnetic nanoparticles (MNPs). The extracted analytes were desorbed using acetonitrile. The obtained extraction solution was analyzed by HPLC-UV. The main affecting factors on the extraction efficiency including pH, sonication time, amount of sorbent, salt concentration, and desorption conditions were optimized in detail. Under the optimum conditions, good linearity was obtained in the range of 2.5-250.0 µg/ L with reasonable linearity (R2 > 0.99) and the limits of detection (LODs) ranged between 0.5 and 1.0 µg/L (based on S/N = 3). Repeatability (intra-day precision) based on five replicates and preconcentration factors were calculated to be 3.6%-4.7% and 87-116, respectively. Relative recoveries in ointment samples at two spiked levels of the target analytes were obtained in the range of 90.0%-103.2%. The results illustrated that the Fe3O4@Cu@ b-TMP-DTPA NPs have the capability of extraction of steroid drugs from ointment samples.

Electrochemically controlled fiber-in-tube solid-phase microextraction method for the determination of trace amounts of antipsychotic drugs in biological samples.

In this study, a novel 'fiber-in-tube' configuration was applied to electrochemically controlled fiber-in-tube solid-phase microextraction of antipsychotic drugs (perphenazine and chlorpromazine) from biological samples. To prepare an electrochemically controlled fiber-in-tube solid-phase microextraction column, first eight stainless-steel wires were placed into the stainless-steel column. Then, a nanostructured Cu-Cr-Al ternary layered double hydroxide/polythiophene coating was prepared on the inner surface of the stainless-steel tube and on the surfaces of the stainless-steel wires by a facile in situ electrodeposition method. The nanostructured coating exhibited enhanced long lifetime, good mechanical stability, high porosity, and large specific surface area compared with polythiophene and Cu-Cr-Al layered double hydroxide coatings. Under the optimal conditions, the limits of detection were in the range of 0.07-0.8 µg/L. This method showed good linearity for perphenazine and chlorpromazine in the ranges of 0.3-300 and 0.2-300 µg/L, respectively, with coefficients of determination more than 0.9982. The inter- and intra-assay precisions (RSD%, n = 3) were in the ranges of 3.0-5.1 and 2.5-4.5% at three concentration levels of 5, 25 and 50 µg/L, respectively. Finally, the method was applied for the analysis of the drugs in human urine and plasma samples.

Evaluation of highly efficient on-line yarn-in-tube solid phase extraction method for ultra-trace determination of chlorophenols in honey samples.

In this study a novel "yarn-in-tube" configuration was introduced by packing cotton yarn inside stainless steel cartridge named packed yarn-in-tube solid phase extraction (yarn-IT-SPE) followed by high performance liquid chromatography. For the first time, cotton yarns were coated with a new polypyrrole@copper-chromium-iron ternary layered double hydroxide nanocomposite (Yarn@PPy@Cu-Cr-Fe LDH). The yarn@PPy@Cu-Cr-Fe LDH sorbent exhibited flexible substrate, high porosity, a three-dimensional, high sorbent loading, long lifetime, good mechanical stability, high anion-exchange capacity and large specific surface area as a result it is a good choice for the separation and preconcentration of acidic cholorophenols in honey samples. Several important factors affecting extraction efficiency such as extraction and desorption times, pH of solution and flow rates of the sample solution and eluent were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.05-0.07 µg L-1. This method showed good linearity for chlorophenols in the range of 0.10-500 µg L-1, with coefficients of determination better than 0.9989. The inter- and intra-assay precisions (RSD%, n = 5) were in the range of 3.2-4.9% and 2.1-3.6% at three concentration levels of 2, 10 and 20 µg L-1, respectively. The validated method was successfully applied for analysis of 4-chloro-, 2,4-dichloro-, and 2,4,6-trichloro phenols in honey samples.

Functionalized layered double hydroxide with nitrogen and sulfur co-decorated carbondots for highly selective and efficient removal of soft Hg2+ and Ag+ ions.

A facile composite was fabricated via direct assembly of nitrogen and sulfur co-decorated carbon dots with abundant oxygen-containing functional groups on the surface of the positively charged layered double hydroxide (N,S-CDs-LDH). The novel N,S-CDs-LDH demonstrates highly selective bindings (M-S) and an extremely efficient removal capacity for soft metal ions such as Ag+ and Hg2+ ions. N,S-CDs-LDH displayed a selectivity order of Ag+> Hg2+ >> Cu2+ >>> Pb2+ > Zn2+ > Cd2+ for their adsorption. The enormous capacities for Hg2+ (625.0 mg g-1) and Ag+ (714.3 mg g-1) and very high distribution coefficients (Kd) of 9.9 × 106 mL g-1 (C0 = 20 mg L-1) and 2.0 × 107 mL g-1 (C0 = 20 mg L-1) for Hg2+ and Ag+, respectively, place the N,S-CDs-LDH at the top of LDH based materials known for such removal. The adsorption kinetic curves for Hg2+ and Ag+ fitted well with the pseudo-second order model. For Hg2+ and Ag+, an exceptionally rapid capture with removal ∼100% within 80 min was observed (Cions = 30 mg L-1 and V/m ratio of 1000). The adsorption isotherms were well described using Langmuir isotherm. The N,S-CDs-LDH was successfully applied to highly efficient removal of Hg2+ and Ag+ from aqueous solutions.

Fabrication of zwitterionic histidine/layered double hydroxide hybrid nanosheets for highly efficient and fast removal of anionic dyes.

In this work, the bio-nanohybrids of magnesium-aluminum layered double hydroxide intercalated with zwitterionic histidine (His-LDH) was synthesized. The crystal phase, morphology, and nanostructure of the as-prepared His-LDH were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and nitrogen adsorption-desorption methods. The His-LDHs were used to remove anionic dyes, including Congo red (CR), indigo carmine (IC) and sunset yellow FCF (SY) from aqueous solutions. The detailed investigation of the kinetics and the adsorption isotherms of CR, IC and SY from aqueous solutions showed that the dyes adsorb rapidly, in accordance with a pseudo-second-order kinetics and a Freundlich adsorption isotherm model. The remarkably high adsorption capacity of the dyes on the His-LDH (efficiency of CR removal, 99.98%; maximum specific removal qmax, 1112 mg g-1; efficiency of IC removal, 98.98%; qmax, 625 mg g-1; and efficiency of SY removal, 99.78%; qmax, 400 mg g-1) is rationalized on the basis of electrostatic interactions as well as π-π and H-bonding interactions between the His-LDH adsorbent and the acidic dyes. Adsorption experiments indicate that the resulting His-LDH has great potential applications as an environmentally friendly material for the swift removal of acidic dyes from aqueous solutions.

Development of electrochemically controlled packed-in-tube solid phase microextraction method for sensitive analysis of acidic drugs in biological samples.

In the present research, for the first time, a novel "packed-in-tube" configuration has been applied to electrochemically controlled in-tube solid phase microextraction, followed by high performance liquid chromatography. In order to prepare a mini packed column, small beads of stainless steel were first placed into the stainless steel column. Then, a nanostructured polypyrrole film was prepared on the internal surface of a stainless steel tube and the surface of stainless steel particles through a facile in-situ electrodeposition method. Filling the column with tiny particles of stainless steel effectively reduces the dead volume of the extraction tube and increases the extraction phase volume. The column was used for separation and preconcentration of diclofenac and mefenamic acid as model analytes from biological samples. Several important factors affecting extraction efficiency, such as extraction and desorption times, flow rates of the sample solution and eluent, and extraction and desorption voltages were investigated and optimized. This method showed good linearity for the drugs in the range of 0.3-200.0 µg L-1, 1.1-200.0 µg L-1, and 1.8-200.0 µg L-1 with coefficients of determination better than 0.9986, 0.9973, and 0.9973 in water, urine, and plasma samples, respectively. Intra- and inter-assay precisions (RSD%, n = 3) were in the range of 2.6-4.8% and 2.9-5.1, respectively, at three concentration levels of 10, 25, and 75 µg L-1. In addition, the limits of detection were in the range of 0.02-0.04 µg L-1. The validated method was successfully applied to the analysis of diclofenac and mefenamic acid in some biological samples. Finally, it is concluded that this method can be a general and reliable alternative to the analysis of ionic compounds in biological matrices.

A nanocomposite prepared from a polypyrrole deep eutectic solvent and coated onto the inner surface of a steel capillary for electrochemically controlled microextraction of acidic drugs such as losartan.

The authors describe a new coating for use in electrochemically controlled in-tube solid phase microextraction (EC-IT-SPME). It consists of a nanocomposite that was prepared from polypyrrole and deep eutectic solvent (DES) by electrochemical deposition on the inner walls of a stainless steel capillary that serves as a working electrode. The hypertension drug losartan acts as an acidic model analyte. The extraction efficiency, mechanical stability, chemical stability and lifetime of the coating were investigated. It is found to be quite stable in relatively acidic and basic media and to be re-usable >450 times without decrease in extraction efficiency. Its extraction capability in comparison to the commercial polypyrrole coating is better by a factor of 1.5. The coated steel capillary was used as the anode (anion-exchanger), and a platinum electrode was used as the cathode. By passing a sample solution through the electrode, losartan can be extracted by applying a positive potential to the flow. In the next step, losartan is electrochemically desorbed and subjected to HPLC analysis with UV detection. Under optimal conditions, losartan can be quantified with limits of detection that range from 50 to 500 ng L-1 depending on the sample matrix. Response is linear in the 0.1-500 µg L-1 concentration range. The inter- and intra-assay precisions (RSDs; in %, for n = 3) are in the range from 2.4-4.6% and from 1.9-3.9%, respectively. Graphical abstract Schematic of the preparation of a nano-structured polypyrrole-deep eutectic solvent nanocomposite coating placed on the inner surface of a stainless steel capillary and used for electrochemically controlled in-tube solid phase microextraction of losartan from biological samples.

On-line packed magnetic in-tube solid phase microextraction of acidic drugs such as naproxen and indomethacin by using Fe3O4@SiO2@layered double hydroxide nanoparticles with high anion exchange capacity.

The authors describe a 3-component nanoparticle system composed of a silica-coated magnetite (Fe3O4) core and a layered double (Cu-Cr) hydroxide nanoplatelet shell. The sorbent has a high anion exchange capacity for extraction anionic species. A simple online system, referred to as "on-line packed magnetic-in-tube solid phase microextraction" was designed. The nanoparticles were placed in a stainless steel cartridge via dry packing. The cartridge was then applied to the preconcentration acidic drugs including naproxen and indomethacin from urine and plasma. Extraction and desorption times, pH values of the sample solution and flow rates of sample solution and eluent were optimized. Analytes were then quantified by HPLC with UV detection. Under optimal conditions, the limits of detection range from 70 to 800 ng L-1, with linear responses from 0.1-500 µg L-1 (water samples), 0.6-500 µg L-1 (spiked urine), and 0.9-500 µg L-1 (spiked plasma). The inter- and intra-assay precisions (RSDs, for n = 5) are in the range of 2.2-5.4%, 2.8-4.9%, and 2.0-5.2% at concentration levels of 5, 25 and 50 µg L-1, respectively. The method was applied to the analysis of the drugs in spiked human urine and plasma, and good results were achieved. Graphical abstract Fe3O4@SiO2@CuCr-LDH magnetic nanoparticles were synthesized and packed in to a stainless steel column. The column was applied to solid phase microextraction of acidic drugs from biological samples.

Simultaneous determination of steroid drugs in the ointment via magnetic solid phase extraction followed by HPLC-UV / 药物分析学报

The copper-coated iron oxide nanoparticles with core-shell were produced by deposition of a Cu shell on Fe3O4 NPs through reduction of Cu2+ ions in solution using NaBH4. Subsequently, the organosulfur compound, bis-(2,4,4-trimethylpentyl)-dithiophosphinic acid (b-TMP-DTPA), was used to form self-assembled monolayer in order to modify sorbent's surface via covalent bonding between Cu and thiol (-SH) terminal groups. The prepared magnetic nanoparticles were characterized by using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and thermo gravimetric analysis (TGA). Then, the application of this new sorbent was investigated to extract the steroid drugs in ointment samples with the aid of ultrasound.An external magnetic field was applied to collect the magnetic nanoparticles (MNPs). The extracted analytes were desorbed using acetonitrile. The obtained extraction solution was analyzed by HPLC-UV. The main affecting factors on the extraction efficiency including pH, sonication time, amount of sorbent, salt concentration, and desorption conditions were optimized in detail. Under the optimum conditions, good linearity was obtained in the range of 2.5-250.0 μg/ L with reasonable linearity (R2 > 0.99) and the limits of detection (LODs) ranged between 0.5 and 1.0 μg/L (based on S/N = 3). Repeatability (intra-day precision) based on five replicates and preconcentration factors were calculated to be 3.6％-4.7％ and 87116,respectively.Relative recoveries in ointment samples at two spiked levels of the target analytes were obtained in the range of 90.0％-103.2％. The results illustrated that the Fe3O4@Cu@ b-TMP-DTPA NPs have the capability of extraction of steroid drugs from ointment samples.

Highly selective and efficient removal of arsenic(V), chromium(VI) and selenium(VI) oxyanions by layered double hydroxide intercalated with zwitterionic glycine.

In this study, a new strategy for highly selective and extremely efficient removal of toxic oxyanions (Cr(VI), Se(VI), and As(V)) from aqueous solutions using zwitterionic glycine intercalated layered double hydroxide (Gly-LDH) was reported. Hence, to investigate the effect of zwitterionic glycine on the adsorption capacity, selectivity factor and adsorption mechanism of LDHs, two NiAl LDHs intercalated with different inter-layer anions, including NO3- and glycine, were synthesized. The obtained results show that the adsorption capacity and selectivity factor of oxyanions through ion exchange mechanism in NO3-LDH is lower than Gly-LDH. Gly-LDH displayed a selectivity order of Se(VI)

Polythiophene/graphene oxide nanostructured electrodeposited coating for on-line electrochemically controlled in-tube solid-phase microextraction.

In this work, a novel polythiophene/graphene oxide (PTh/GO) nanostructured coating was introduced for on-line electrochemically-controlled in-tube solid phase microextraction of amitriptyline (AMI) and doxepin (DOX) as antidepressant drugs. The PTh/GO coating was prepared on the inner surface of a stainless steel tube by a facile in-situ electro-deposition method and it was used as a working electrode for electrochemically control in-tube solid phase microextraction. In the PTh/GO coating, GO acts as an anion dopant and sorbent. The PTh/GO coating, compared to PTh and GO coatings, exhibited enhanced long lifetime, good mechanical stability and a large specific surface area. Regarding the in-tube SPME, some important factors such as the extraction and desorption voltage, extraction and desorption times and flow rates of the sample solution and eluent, which could affect the extraction and separation efficiency of the analytes, were optimized. Total analysis time of this method including the online extraction and desorption time was about 21min for each sample. AMI and DOX were extracted, separated and determined with limits of detection as small as 0.3µgL-1 and 0.5µgL-1, respectively. This method showed good linearity in the range of 0.7-200µgL-1, 2.3-200µgL-1 and 2.9-200µgL-1 for AMI, and in the range 0.9-200µgL-1, 2.5-200µgL-1 and 3.0-200µgL-1 for DOX in water, urine and plasma samples, respectively; the coefficients of determination were also equal to or higher than 0.9976. The inter- and intra-assay precisions (RSD%, n=3) were in the range of 2.8-3.4% and 2.9-3.9% at the three concentration levels of 5, 25 and 50µgL-1, respectively. Finally, under the optimal conditions, the method was applied for the analysis of the drugs in human urine and plasma pretreated samples and good results were obtained.