Magnetic solid-phase extraction of warfarin and gemfibrozil in biological samples using polydopamine-coated magnetic nanoparticles via core-shell nanostructure.

Herein, polydopamine-coated Fe3 O4 spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe3 O4 ) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe3 O4 . The prepared polydopamine-coated Fe3 O4 spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1-200.0 µg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026-0.055 µg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089-0.185 µg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%-3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.

Creatine@SiO2 @Fe3 O4 nanocomposite as an efficient sorbent for magnetic solid-phase extraction of escitalopram and chlordiazepoxide from urine samples through quantitation via HPLC-UV.

An efficient, cost-effective, and fast-synthesis method is presented in the current study to prepare magnetic nanoparticles covered by cheap and nitrogen-rich creatine. The hydrothermal method was used for the synthesis of the magnetic core. The prepared magnetic core was then covered by SiO2 and subsequently functionalized using creatine. The prepared creatine@SiO2 @Fe3 O4 was utilized as a sorbent in the magnetic solid-phase extraction of the selected antidepressants including escitalopram and chlordiazepoxide as the model drugs. The extracted drugs were desorbed by a suitable organic solvent and analyzed by high-performance liquid chromatography equipped with an ultraviolet detection system. The influence of different variables on the magnetic solid-phase extraction method was examined by the Plackett-Burman and Box-Behnken designs for screening and optimization, respectively. Under the obtained optimum conditions, the linear ranges of the method were found to be in the range of 1-500 µg L-1 . The limits of detection and limits of quantification were in the range of 0.27-0.63 µg L-1 and 0.89-1.93 µg L-1 for the selected analytes, respectively. Furthermore, the enrichment factors were found to be 79.8 and 92.7 for chlordiazepoxide and escitalopram, respectively. The method was successfully employed for the analysis of selected drugs in urine samples.

A review on the recent achievements on coronaviruses recognition using electrochemical detection methods.

Various coronaviruses, which cause a wide range of human and animal diseases, have emerged in the past 50 years. This may be due to their abilities to recombine, mutate, and infect multiple species and cell types. A novel coronavirus, which is a family of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), has been termed COVID-19 by the World Health Organization (WHO). COVID-19 is the strain that has not been previously identified in humans. The early identification and diagnosis of the virus is crucial for effective pandemic prevention. In this study, we review shortly various diagnostic methods for virus assay and focus on recent advances in electrochemical biosensors for COVID-19 detection.

In situ electrodeposition of Cu-BDC metal-organic framework on pencil graphite substrate for solid-phase microextraction of some pesticides.

The study focuses on the electrochemical deposition of copper benzene-1,4-dicarboxylate framework (Cu-BDC MOF) on the surface of a very cheap pencil graphite (PG) substrate for utilization as the sorbent in fiber solid-phase microextraction (SPME) of two chosen pesticides, including abamectin and amitraz for the first time. The extracted pesticides were quantified by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The UV detector was set at 236 nm wavelength. Based on the optimized condition, the presented technique showed a good linear range (2-500 µg L-1 and 2-100 µg L-1), suitable limits of detections (LODs = 0.60 and 0.5 µg L-1), satisfactory enhancement factors (EFs = 128 and 105), good absolute recoveries (ARs% = 64% and 53%) and spiking recoveries in the range 87.4-110.0% for amitraz and abamectin, respectively. Intra- and inter-day relative standard deviations were found within the range 1.2-3.8% and 0.6-1.9%, respectively. The method was successfully employed for the quantification of the selected pesticides in strawberry juice, lemon juice, orange juice, tomato juice, and honey.

In-situ formation of Zn-Al layered double oxides on electrochemically anodized nanoporous aluminum film as sorbent for chlorophenols extraction from water and wastewater followed by determination using HPLC.

Herein, we present a simple, cost-effective, and robust strategy for the in-situ preparation of Zn-Al layered double oxides-anodized aluminum thin film via a facile hydrothermal method, followed by calcination treatment of the Zn-Al layered double hydroxide in the air atmosphere. The in-situ prepared Zn-Al layered double oxide-anodized aluminum film was implemented as sorbent for thin film microextraction of four selected chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol), followed by high-performance liquid chromatography-ultraviolet detection. The different variables of the thin film microextraction were screened via Plackett-Burman design and then optimized through Box-Behnken design. Under the optimum condition, the method showed good linear ranges (0.2-200 µg/L) with the coefficient of determinations higher than 0.9938. The calculated limit of detections were between 0.07 and 0.56 µg/L. Relative standard deviations of the method for determination of the analytes at 5 µg/L concentration level (n = 3) were ranged from 3.5 to 3.9% (as interday). The enrichment factors were between 39 and 58. This extraction method was demonstrated to be fast, efficient, and convenient. To study the capability of the developed method for real sample analysis, tap, well, river, and two types of wastewater samples were satisfactorily analyzed.

Glutathione-stabilized Fe3 O4 nanoparticles as the sorbent for magnetic solid-phase extraction of diazepam and sertraline from urine samples through quantitation via high-performance liquid chromatography.

The synthesis and application of glutathione-coated magnetic nanocomposite were introduced with the purpose of developing a stable, cheap, operationally convenient, simple, fast, sensitive, and selective device for the microextraction of diazepam and sertraline for the first time. The prepared glutathione@Fe3 O4 nanocomposite was used as the sorbent in the form of magnetic solid-phase extraction. Afterward, the extracted analytes were desorbed by organic solvent and analyzed by high-performance liquid chromatography-ultraviolet detection. Several influential variables such as desorption time, desorption volume, sample pH, extraction time, and sorbent amount were screened through Plackett-Burman design and then optimized via Box-Behnken design. The obtained results showed that the above-mentioned method enjoys a good linear range (0.2-500 µg/L) with the coefficient of determination higher than 0.9927, low limits of determination (0.07-0.24 µg/L), acceptable limits of quantification (0.22-0.93 µg/L), good enrichment factors (128 and 153), and good spiking recoveries (95-105%) for diazepam and sertraline under the obtained optimized condition. Analyzing the real samples results in the confirmation of the presented method and it can be applied for the analysis of various organic compounds in biological samples.

Ordered macro/micro-porous metal-organic framework of type ZIF-8 in a steel fiber as a sorbent for solid-phase microextraction of BTEX.

An ordered array of macropores on microporous metal-organic framework crystals was developed. This array facilitates analyte diffusion in microextraction applications. A prototypical zeolitic imidazolate framework (ZIF-8) was synthesized in the interstitial voids of a polystyrene bead packing of sub-µm polystyrene beads. After removal of polystyrene by dimethylformamide, a single-crystal ordered macroporous ZIF-8 material (SOM-ZIF-8) was obtained. The resulting µm-sized SOM-ZIF-8 crystals are based on a fully-microporous structure containing a macroporous network. The SOM-ZIF-8 crystals were placed in a stainless-steel fiber and applied as a sorbent for the extraction of benzene, toluene, ethylbenzene, and xylenes (BTEX) by headspace solid-phase microextraction (HS-SPME). The fiber was applied to the HS-SPME of BTEX from wastewater samples followed by GC with flame ionization detection. A Plackett-Burman design and Box-Behnken design were carried out to evaluate the variables affecting the method. Figures of merit include (a) limits of detection of 1.0-12 ng·L-1, (b) linear ranges of 0.004-50 µg·L-1, (c) relative standard deviations of 4.6-6.7%, and (d) excellent fiber-to-fiber reproducibility (5.6-6.7% for n = 3). Spiking recoveries between 92 and 106% were obtained for BTEX analysis in wastewater samples. The introduction of an ordered macroporous network on microporous ZIF-8 crystals enhanced analyte uptake. This increases the extraction performance by a factor of 2.5-3.1 when compared to analogous ZIF-8 crystals that lack templated macropores. Graphical abstract BTEX extraction is enhanced by templating an ordered macroporous network in microporous crystals as exemplified with the single-crystal ordered macropore zeolitic imidazolate framework-8 (SOM-ZIF-8). Graphical Abstract contains poor quality of image inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.The file in original format has been attached.

Emerging materials for sample preparation.

This review provides an update on the implementation of emerging materials as sorbents for sample preparation in combination with chromatographic separation. We have focused on recent applications of metal-organic frameworks, layered double hydroxides, porous carbons obtained from polymers or biomass precursors, and silicates (clays and zeolites). The review is directed toward the strategies followed by the authors to engineer suitable supports enabling the application of materials with unconventional size and shape as high-performance sorbents to explore new boundaries in sample pretreatment in manual or automated modes.

Automated solid-phase extraction of phenolic acids using layered double hydroxide-alumina-polymer disks.

The application of layered double hydroxide-Al2 O3 -polymer mixed-matrix disks for solid-phase extraction is reported for the first time. Al2 O3 is embedded in a polymer matrix followed by an in situ metal-exchange process to obtain a layered double hydroxide-Al2 O3 -polymer mixed-matrix disk with excellent flow-through properties. The extraction performance of the prepared disks is evaluated as a proof of concept for the automated extraction using sequential injection analysis of organic acids (p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, gallic acid) following an anion-exchange mechanism. After the solid-phase extraction, phenolic acids were quantified by reversed-phase high-performance liquid chromatography with diode-array detection using a core-shell silica-C18 stationary phase and isocratic elution (acetonitrile/0.5% acetic acid in pure water, 5:95, v/v). High sensitivity and reproducibility were obtained with limits of detection in the range of 0.12-0.25 µg/L (sample volume, 4 mL), and relative standard deviations between 2.9 and 3.4% (10 µg/L, n = 6). Enrichment factors of 34-39 were obtained. Layered double hydroxide-Al2 O3 -polymer mixed-matrix disks had an average lifetime of 50 extractions. Analyte recoveries ranged from 93 to 96% for grape juice and nonalcoholic beer samples.

Three-dimensional Pd/Pt bimetallic nanodendrites on a highly porous copper foam fiber for headspace solid-phase microextraction of BTEX prior to their quantification by GC-FID.

The preparation of bimetallic Pd/Pt nanofoam for use in fiber based solid-phase microextraction (SPME) is described. First, a highly porous copper foam was prepared on the surface of an unbreakable copper wire by an electrochemical method. Then, the substrate was covered with metallic Pd and Pt using galvanic replacement of the Cu nanofoam substrate by applying a mixture of Pd(II) and Pt(IV) ions. The procedure provided an efficient route to modify Pd/Pt nanofoams with large specific surface and low loading with expensive noble metals. The fiber was applied to headspace SPME of benzene, toluene, ethylbenzene and xylene (BTEX) (as the model compounds) in various spiked water and wastewater samples. It was followed by gas chromatography-flame ionization detection (GC-FID). A Plackett-Burman design was performed for screening the experimental factors prior to Box-Behnken design. Compared with the commercial PDMS SPME fiber (100 µm), it had higher extraction efficiency for BTEX. Under the optimum conditions, the method has low limits of detection (0.16-0.35 µg L-1), a wide linear range (1-200 µg L-1), relative standard deviations between 5.8 and 10.5%, and good recoveries (>85% from spiked samples). Graphical abstract Schematic presentation of a three-dimensional Pd/Pt bimetallic nanodendrites supported on a highly porous copper foam fiber for use in headspace solid phase microextraction of BTEX. They were then quantified by gas chromatography-flame ionization detector.

Bacteria-templated ZIF-8 embedded in polyacrylonitrile nanofibers as a novel sorbent for thin film microextraction of benzoylurea insecticides.

In the present work, the rod-like ZIF-8 (ZIF8@E coli) was prepared by fast, easy and environmentally friendly method of biomimetic mineralization with Escherichia coli bacteria as a bio-template and was exploited for the first time in the microextraction. In this regard, electrospun nanofiber mats of polyacrylonitrile (PAN) and ZIF8@E coli were prepared by electrospinning method and used as a new sorbent for thin film microextraction (TFME) of benzoylurea insecticides such as Hexaflumuron and Teflubenzuron as model analytes. The PAN/ZIF8@E coli nanocomposite was characterized using electron scanning microscopy and various spectroscopy techniques. Factors affecting the proposed extraction method were screened and optimized using the experiment design strategy. Then, the model analytes were measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detector after microextraction. Satisfactory figures of merit were obtained for suggested TFME-HPLC-UV under optimum conditions. The suitable linearity varied in the range of 0.5-200 µg L-1 with R2 greater than 0.9968. The limit of detections for Hexaflumuron and Teflubenzuron were 0.12 and 0.15 µg L-1, respectively. The application of the method in the real sample was investigated by analyzing the selected analytes in environmental water and food samples. The spiking recovery of the selected analytes varied in the range of 93.0-109.8 % (RSD≤7.68). The results confirm the efficient application of this new sorbent in TFME approach. Considering the high availability, ease of production, and environmental friendliness of bacteria along with the significant improvement of metal-organic framework (MOF) growth efficiency, biomimetic mineralization is expected to be efficient method for the synthesis of ordered MOFs for use in extraction fields.

Modification of cellulose substrate by in situ synthesis of metal-organic framework-5 for thin film microextraction of some non-steroidal anti-inflammatory drugs and their measurement by high-performance liquid chromatography-ultraviolet detector.

This work, reports the successful preparation a thin film by a simple and inexpensive process for quantification of a model analytes in the urine sample using HPLC-UV. To this end, cellulose paper was employed as a substrate for the in-situ synthesis of MOF-5, to increase the resistance of the prepared film. The prepared film can be reused 26 times with no reduction in its performance. The thin film prepared by MOF-5 modified cellulose substrate was utilized in thin film microextraction (TFME) method for the extraction and preconcentration of naproxen, aspirin, tolmetin, and celecoxib. Under optimal conditions, the linear dynamic range of the target analytes was 2-500 µg L-1 with correlation coefficients (R2) ranging from 0.9961 to 0.9990. Also, the limits of detection (LODs), the limits of quantification (LOQs) and relative standard deviation (RSD%) of the proposed method for selected analytes ranged between 0.57 and 0.77 µg L-1, 1.7 to 2.3 and 3.5 % to 6.2 %, respectively. Moreover, relative recoveries varied from of 94 % to 108 %, indicating the absence of matrices effect in the proposed method. Eventually, the TFME was successfully used for the extraction of selected analytes from urine samples.

Keggin-type polyoxometalate embedded polyvinylidene fluoride for thin film microextraction of organophosphorus pesticides.

The present research is the first report on the application of Keggin-type phosphotungstic acid/polyvinylidene fluoride membrane. This compound as a simple, cost-effective and novel sorbent was used for the extraction and pre-concentration of two organophosphorus pesticides in real samples in the thin film solid-phase microextraction (TFME) method. TFME as one of the sub-branches of solid phase microextraction resolves the problems of SPME methods, including their limited absorption capacity. These extraction methods have a high surface-to-volume ratio, which improves their sensitivity compared to other geometries. Under optimal conditions, the limit of detections (LODs), the limit of quantifications (LOQs), and relative standard deviation (RSD) of this method varied in the ranges of 0.29-0.31 µg L-1, 0.96-1.0 µg L-1, and 3.9%-6.2%, respectively. This method showed a linear dynamic range (LDR) of 1.0-500 µg L-1 with a coefficient of determination (r2) above 0.9978. This promising method was used to analyze malathion and diazinon.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography.

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (H3PW12O40). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME). The method was used for the extraction of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6- trichlorophenol from tap water, river water, and tea sample. The extracted target analytes were quantified via high-performance liquid chromatography-UV detection. The figures of merit of the method such as, linear dynamic ranges (LDRs), limit of detections (LODs) and, limit of quantifications (LOQs), were determined based on the obtained optimum condition. Based on the results, the LDR was between 1 and 500 µg L - 1 and r2 higher than 0.9960. The LODs and LOQs were obtained in the ranges of 0.28-0.36 µg L - 1 and 0.92-1.1 µg L - 1, respectively. The relative standard deviations ((RSDs% for inter-and intra-day) of the method for the extraction of target analytes were calculated in two different concentrations of (2 and 10 µg L - 1) and (5 and 10 µg L - 1) between 3.70% - 5.30% and 3.50% - 5.70%-respectively. The enrichment factors were obtained between 57 and 61. In order to investigate the accuracy of the method, also the relative recovery was obtained, between 93 and 105%. Finally, the proposed method was used for the extraction of the selected analytes in different water and tea samples.

Porous agarose/chitosan/graphene oxide composite coupled with deep eutectic solvent for thin film microextraction of chlorophenols.

In this project, a three-dimensional graphene oxide coated agarose/chitosan (ACGO) porous film was synthesized and utilized as sorbent in thin film microextraction (TFME) technique to extract 4-chlorophenol, 2,4-dichlorophenol, 3,5-dichlorophenol and 2,4,6-trichlorophenol as the model analytes in various real samples such as agricultural waste water, honey and tea samples. In addition, deep eutectic solvent made of tetra ethyl ammonium chloride/chlorine chloride was used as a desorption solvent. The effect of various variables, such as: extraction time, stirring rate, solvent desorption volume, desorption time, ionic strength and solution pH on the extraction efficiency of the method was studied and optimized. Under the optimized condition, the linear range of the method was obtained in the range of 0.1-500µgL-1 for testing analytes (4-chloropheol=0.1-500µgL-1, 2,4-dichlorophenol=0.2-500µgL-1, 3,5-dichlorophenol=0.5-500µgL-1 and 2,4,6-trichlorophenol=0.2-500µgL-1). The obtained correlation coefficients (r2) were between 0.9984 and 0.9994. The limits of detection (LODs) were also calculated between 0.03 - 0.13µgL-1. The relative standard deviations (RSDs%) were obtained in the range of 2.8 to 5.9%. The enrichment factor (EFs) values for the studied analytes were also obtained in the range of 33.4-35.8. In addition, the obtained results indicated that the prepared film can potentially be used for more applications in the field of environment, food safety, and drug analysis.

Nanoporous carbon fiber derived from Cu-BDC metal organic framework @pencil graphite as a sorbent for solid phase microextraction of acetamiprid and imidacloprid.

Solid-phase microextraction (SPME) is a sample pretreatment technique for enrichment of trace level of compounds from complex matrices. The fiber coating, as an extraction phase, is the significant part of SPME, which specifying the analytical performance of the developed SPME. In this study, a novel in situ fabricated Cu@porous carbon fiber that derived from copper benzene-1,4-dicarboxylate framework@pencil graphite (Cu-BDC MOF@PG) fiber was prepared as a SPME fiber. The Cu-BDC MOF was electrodeposited on the surface of pencil graphite. The Cu@porous carbon fiber with nanoporous structure was constructed by the direct carbonization of the electrosynthesized fiber. The Cu@porous carbon fiber showed high analytical performance for direct immersion SPME (DI-SPME) of acetamiprid and imidacloprid in fruit and vegetable samples. The SPME method was coupled by high-performance liquid chromatography-ultraviolet detection (SPME-HPLC-UV) for determination of the analytes. Under the optimized condition, good linear ranges (1-500 µg L-1 and 0.5-200 µg L-1) and acceptable limits of detection (LODs = 0.30 and 0.15 µg L-1), appropriate spiking recoveries in the range 87-109.0% were attained for acetamiprid and imidacloprid, respectively. Intra- and inter-day relative standard deviations were found within the ranges of 2.35-3.46% and 3.30-3.70%, respectively. These results signify promising potential of the in situ fabricated porous carbon fiber for SPME applications. Considering that most of the pencil graphite is made of carbon, after the carbonization of the Cu-BDC MOF@PG fiber, a unified porous carbon fiber is obtained. Compared to other reported procedures, in situ direct carbonization of Cu-BDC MOF@PG fiber was a one-step and straightforward method to fabricate carbon fiber.

Combination of in-situ electro synthesized Zn-Al-LDH@ pencil graphite fiber and three phase hollow fiber LPME for microextraction of some antibiotics in urine samples and quantification via HPLC-UV.

In the present study, a combination of two useful extraction techniques including fiber solid phase microextraction based on the new synthesized sorbent and the porous hollow fiber liquid phase microextraction is reported. The selective anion-exchangeable Zn-Al-layered double hydroxide as a fiber was electrodeposited on the surface of pencil graphite substrate through simple and cost-effective method. The prepared fiber was characterized and put into the lumen of the porous hollow fiber, which was filled by alkaline solution. The obtained optimum condition for the method was as follows: donor phase HCl concentration of 0.10 mM, acceptor phase NaOH concentration of 7.60 mM and extraction time of 16 min. It is necessary to adjust the concentration of the donor phase in order to extract acidic analytes from an aqueous sample into an organic phase. The method was used for the quantification of three antibiotics including amoxicillin, ciprofloxacin and cefixime. The extracted antibiotics were analyzed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). In the optimal conditions, the linearity of the proposed method was in the range of 0.50-500.00 µg L-1 for selected analytes in water and urine matrices. All calibration curves showed determination of coefficient higher than 0.9958. The limits of detection and limits of quantification were calculated to be between 0.08 and 0.16 µg L-1 and 0.28-0.56 µg L-1, respectively. In order to define the precision of the method, the inter-day and intra-day relative standard deviations were determined between 3.25 and 5.73% in the three selected concentrations. The enrichment factors (EFs) were between 46.20 and 55.81 for selected drugs. Moreover, the calculated absolute recoveries were between 69.30 and 83.71%. The relative recoveries were obtained in the range of 93.00-105.00%. The proposed method was also employed for analysis of various urine samples containing the selected drugs. The obtained recoveries indicated that the method was useful and applicable in complicated biological samples.

Template-directed synthesis of three-dimensional metal organic framework 199-derived highly porous copper nano-foam fiber for solid-phase microextraction of some antibiotics prior to their quantification by High performance liquid chromatography.

The in-situ preparation of three-dimensional MOF-199 (3D MOF-199) derived from the electrochemically prepared highly porous nano Cu foam on the surface of a flexible copper wire is reported. The 3D-Cu foam coating was used as a precursor and template for fabrication of MOF-199. The microextraction ability of the in-situ prepared 3D-MOF-199 fiber was evaluated using the prepared fiber for solid phase microextraction (SPME) of selected antibiotics including amoxicillin, azithromycin, ciprofloxacin, cefixime and gentamicin coupled to high-performance liquid chromatography with UV detection. Under the optimized condition, the calibration curves were linear in the range of 1-100 µg L - 1 (r2 above 0.9921) for both water and urine matrices. Limits of detection and limits of quantification were 0.14-0.62 µg L - 1 and 0.53-2.17 µg L - 1 in the selected matrices, respectively. In addition, the repeatability of the method was evaluated by considering the relative standard deviation (RSD%). The intra-day and inter-day RSDs of the method with the single fiber was in the range of 2.8% to 4.9% and from 3.1% to 4.9%, respectively. Furthermore, the fiber-to-fiber reproducibility ranged from 2.9% to 5.5%. The enrichment factors were also in the range of 32 to 55. Finally, the method was successfully used for analysis of amoxicillin, azithromycin, ciprofloxacin, cefixime and gentamicin in urine samples. Relative recoveries for spiked urine samples were in the range of 90-105%.

Template-directed synthesis of zeolitic imidazolate framework-8 derived Zn-Al layered double oxides decorated on the electrochemically anodized nanoporous aluminum substrate for thin film microextraction of chlorophenols followed by determination with high-performance liquid chromatography.

In this work, hierarchical ZIF-8 coated anodized aluminum foil was prepared through in situ template-directed method without addition of any zinc salt. The hierarchical sorbent was synthesized by the formation of the final HZIF-8 on the previously created layered double oxide (LDO) template. The LDO template was created by calcining the firstly in situ prepared desired layered double hydroxide (LDH) precursor coated on the electrochemically anodized porous Al foil in an air atmosphere. The microextraction ability of the extracting device was studied through direct immersion thin film microextraction (DI-TFME). The extracted analytes were quantified by high-performance liquid chromatography equipped by UV detector (HPLC-UV). The present strategy was used for the simultaneous extraction and quantification of four selected chlorophenols (CPs) (as model analyte). The variables of the TFME were optimized using response surface methodology (Plackett-Burman and Box-Behnken design). Under the obtained optimum condition, the prepared film presented acceptable extraction properties including low limits of detection (0.03-0.22 µgL-1), good linear ranges (0.2-200 µgL-1, r2 > 0.9918) and satisfactory reproducibility (relative standard deviation, 3.6 < RSD < 5.8% for one film as inter- and intra-day RSD, 4.8 < RSD < 5.3% for film to film). Moreover, the obtained enrichment factors were in the range of 56-76. The kinetics and adsorption isotherm of the selected analytes adsorption to the prepared sorbent were also investigated. The maximum adsorption capacities of the selected analytes on the prepared sorbent were in the range of 26.4-80.1 mg g-1. The adsorption isotherm obeyed the Langmuir and Freundlich models. Moreover, the adsorption of the selected chlorophenols on the prepared film followed the pseudo-second-order kinetic model. Finally, the HZIF-8 film was utilized for the quantification of selected CPs in different types of water and wastewater samples. The results showed satisfactory relative recoveries (93-102%) and acceptable precisions (3.6 < RSD < 9.2%).

In-situ synthesis of nanocubic cobalt oxide @ graphene oxide nanocomposite reinforced hollow fiber-solid phase microextraction for enrichment of non-steroidal anti-inflammatory drugs from human urine prior to their quantification via high-performance liquid chromatography-ultraviolet detection.

The in-situ synthesis and application of nanocubic Co3O4-coated graphene oxide (Co3O4@ GO) was introduced for the first time to present a cost-effective, stable and convenient operation and a simple device for hollow fiber solid-phase microextraction (HF-SPME) of four selected nonsteroidal anti-inflammatory drugs (NSAIDs) including diclofenac, mefenamic acid, ibuprofen and indomethacin. The extracted analytes were desorbed by an appropriate organic solvent and analyzed via high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The prepared sorbent was approved using different characterization methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The variables effective on the Co3O4@GO-HF-SPME method including extraction time, desorption time, desorption solvent volume, sample pH, stirring rate and ionic strength were screened via Plackett-Burman design and then optimized by Box-Behnken design. Under optimal condition, the calibration curves were linear within the range of 1.0-200.0 µg L-1 of analyte concentration with detection limits of 0.18-1.1 µg L-1 and the relative standard deviations less than 10.1%. The limits of quantification (LOQs) were in the range of 0.60-3.67 µg L-1. Matrix effect was not observed with this method; therefore, standard addition is not necessary for quantification of target compounds. The enrichment factors were obtained in the range of 49-68. The relative recoveries of the urine sample analysis were calculated in the range of 93-102%. Finally, the presented method exhibited good sensitivity, excellent repeatability, high reusability and acceptable precision, which will be a promising method to analyze various nonsteroidal anti-inflammatory drugs in urine samples.