A new approach of magnetic field application in miniaturized pipette-tip extraction for trace analysis of four synthetic hormones in breast milk samples.

Herein, a novel homemade electrical device was designed, including two pieces of external neodymium magnets, providing a reciprocating magnetic field to introduce a magnetic-assisted dispersive pipette-tip micro solid-phase extraction. To evaluate the performance efficiency of the proposed method, a novel magnetic calcined GO/SiO2@Co-Fe nanocube sorbent was synthesized, filled into the pipette-tip, exposed to the reciprocating magnetic field, and applied for the preconcentration of some hormone therapy drugs in human biological matrices. The effective adsorption and desorption parameters were optimized using a rotatable central composite design and one-variable-at-a-time approaches. Under the optimized conditions, the target analytes' detection limits were found to be below 0.02 ng mL-1. Moreover, the calibration curves were linear in the range of 0.03-500.00 ng mL-1 (R2 > 0.9966), with RSDs% less than 7.8 %. Eventually, the established method was applied to extract the analytes from breast milk samples, followed by LC-ESI-MS/MS analysis.

Lead analysis by µSPE/FF-AAS: A comparative study based on dimethylglyoxime functionalized silica-coated magnetic iron/graphene oxides.

Here, four new sorbents based on dimethylglyoxime (DMG) functionalized silica-coated magnetic iron/graphene oxides (Fe3O4/MGO) were synthesized. A comparative study was performed among them to evaluate the different substrates and the role of the spacer in improving the lead extraction efficiency and selecting the most efficient sorbent. Based on experimental results, MGO@SiO2@3-chloropropyltrimethoxysilane@DMG was selected for magnetic dispersive µSPE of lead followed by flame (FAAS) and graphite furnace atomic absorption spectroscopy (GFAAS). The sorbents were characterized by FT-IR, FE-SEM, EDX, TEM, and Zeta potential. Sorbent amount (40.5 mg), sample pH (7.7), sonication time of adsorption and desorption procedures (9 min), and volume and acid concentration (2.2 mL of 2.7 mol L-1 nitric acid) were optimized using experimental design. Linearity of 20.0-600.0 ng mL-1 and 0.5-3.0 ng mL-1 resulted by FAAS and GFAAS, respectively. LODs were 7.0 and 0.2 ng mL-1 by FAAS and GFAAS, respectively. Intra- and inter-day RSDs% (n = 3) at two concentration levels of 3.0 and 100.0 ng mL-1 were below 7.6%.The adsorption capacity was 45.05 mg g-1. The adsorption isotherm showed a better fitting with the Langmuir model. Relative recoveries (%) of 87.8-115.1% were obtained for measuring trace amounts of lead in water, hair, and nail samples.

Trace determination of antifungal drugs in biological fluids through a developed approach of hydrogel-based spin-column micro-solid-phase extraction followed by LC-MS/MS analysis.

In the present research, a blended polyacrylamide-chitosan hydrogel was synthesized. For the first time, the prepared sorbent was efficiently employed in a hydrogel-based spin-column setup as a promising format. The proposed method was applied for monitoring the trace amounts of ketoconazole, clotrimazole, and miconazole in blood samples. Effective adsorption and desorption parameters were optimized using a central composite design and the one-variable-at-a-time method. Under the optimal conditions, the calibration curves were linear in the range of 15.0-1000.0, 1.0-1000.0, and 2.0-1000.0 ng mL-1 for ketoconazole, clotrimazole, and miconazole, respectively, along with intra- and interday precision less than 8.4%. Limits of detection were obtained between 0.2 and 5.0 ng mL-1 . The preconcentration factors were found in the range of 5.9-7.8. The introduced method was successfully applied for micro-solid-phase extraction of trace amounts of target antifungal drugs in blood samples, followed by liquid chromatography-tandem mass spectrometry. Satisfactory relative recoveries of 94.5-103.5% were obtained, implying method reliability. Overall, the proposed method provides good accuracy and repeatability, high reusability, and good applicability to determine antifungal drugs in complex biological matrices.

Application of magnetic nanomaterials in magnetic-chromatography: A review.

With the advent of nanotechnology and its development, there have been dramatic advances in various aspects of diverse sciences. Nanotechnology encompasses the manipulating matter to create nanometre-scale materials with prodigious features and their implementation in a vast range of applications. The topic that is the current debate in today's scientific community and the transformation origin in modern technologies. Magnetic nanomaterials belong to the group of materials mainly consisting of a magnetic component, such as iron, and a chemical functionality agent. Hitherto, several reports on these materials have been published in various sciences, including chemistry, and their applications have been discussed from different perspectives. One of the most interesting aspects of these materials is in a special type of chromatographic techniques, called "magnetic-chromatography" as well as "magneto-chromatography". The subject that has been somewhat underestimated compared to the other practical aspects of these materials. This review devotes to the recent issue and seeks to address the principles, benefits, challenges, analytical data, and potential applications of magnetic-chromatography in ions separation, size fractionation of magnetic nanoparticles, and isolation of biologically active organic molecules. Also, the new aspects and future trends of this technique are discussed.

Electrochemically synthesized NiFe layered double hydroxide modified Cu(OH)2 needle-shaped nanoarrays: A novel sorbent for thin-film solid phase microextraction of antifungal drugs.

Herein, we applied a simple electrosynthesis process to deposit nickel-iron layered double hydroxides (NiFe LDH) on the surface of copper hydroxide (Cu(OH)2) needle-shaped nanoarrays and introduce a new sorbent for thin-film solid phase microextraction (TF-SPME). For this purpose, the nanoarrays were grown via electrochemical anodization on a copper foil's surface and then modified with NiFe LDH. The synthesized sorbent was characterized by field emission-scanning electron microscopy, Brunauer-Emmett-Teller (BET), and Barrett-Joiner-Halenda (BJH) analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The Cu(OH)2-NiFe LDH based TF-SPME method was used to measure antifungal drugs in veterinary plasma samples followed by HPLC-UV analysis. The effects of various parameters in the extraction efficiency, including pH (5.0), extraction time (20 min), stirring rate (500 rpm), and salt effect (5.0%), type of eluent (acetonitrile), eluent volume (100 µL) and desorption time (5 min) were thoroughly optimized. Under the optimum conditions, limits of detection for ketoconazole, clotrimazole, and miconazole were obtained below 10 ng mL-1. Intra-day, inter-day and film-to-film RSDs% were obtained less than 6.2%, 7.3% and 7.0%, respectively. Moreover, calibration plots were linear from 30 to 5000 ng mL-1 for ketoconazole, 8.0-1000 ng mL-1 for clotrimazole, and 15-1000 ng mL-1 for miconazole, with determination coefficients between 0.9937 and 0.9971. Finally, good relative recoveries (%) in the range of 85-97% were obtained for measuring trace amounts of antifungal drugs in dogs' plasma samples. As a result, the method can be considered as an appropriate alternative to the conventional sample preparation methods for measuring trace amounts of antifungal drugs in biological samples.

Electrochemically deposition of ionic liquid modified graphene oxide for circulated headspace in-tube solid phase microextraction of naphthalene from honey samples followed by on-line liquid chromatography analysis.

In this work, an inexpensive, fast, and selective ionic liquid modified graphene oxide (GO-IL) was synthesized and electrochemically deposited on the inner surface of a stainless-steel tube. Then, it was applied for circulated headspace in-tube solid-phase microextraction (CHS-IT-SPME) of naphthalene from honey samples. Next, the coated tube was replaced with the sample loop of a six-port injection valve for on-line desorption and further HPLC-UV analysis of naphthalene. The sorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX). Different parameters affecting the procedure efficiency, including extraction temperature, extraction time, salt concentration, and sample volume were optimized by central composite design and response surface methodology. Under the optimum conditions, the calibration curve was linear within the range of 0.3-200 ng mL-1, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL-1 and 0.3 ng mL-1, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL-1 were obtained 3.9% and 5.0%, respectively. Also, good tube-to-tube reproducibility of 5.3% was achieved. Finally, the method was successfully applied for measuring trace amounts of naphthalene in honey samples. Relative recoveries were calculated within the range of 90.0-106.5%, indicating excellent efficiency of the proposed method.

In-tube stir bar sorptive extraction based on 3-aminopropyl triethoxysilane surface-modified Ce-doped ZnAl layered double hydroxide thin film for determination of nonsteroidal anti-inflammatory drugs in saliva samples.

A thin-film based on 3-aminopropyl triethoxysilane surface-modified Ce-doped zinc-aluminum layered double hydroxide was synthesized on the inner surface of an aluminum tube. It has been applied to in-tube stir bar sorptive extraction of nonsteroidal anti-inflammatory drugs in saliva samples followed by high-performance liquid chromatography. The sorbent was characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and elemental mapping. The extraction parameters including sample pH (4.2), extraction time (10 min), stirring speed (800 rpm), type of eluent (acidified tetrahydrofuran), eluent volume (100 µL), and desorption time (6 min) were thoroughly optimized. Under the optimum conditions, limits of detection were found to be less than 5.0 ng mL-1. Calibration plots were linear within the range 10-1000 ng mL-1 (R2 > 0.9982). Absolute recoveries were calculated in the range 63.5 to 72.4%. The repeatability (intra- and inter-day precision) and reproducibility (tube-to-tube precision) at concentrations of 50, 250, and 500 ng mL-1 were less than 7.6% and 9.4%, respectively. The method accuracy based on the relative error was calculated at these concentrations and ranged from - 4.9 to - 9.3% for intra-day relative error (%) and - 6.8 to - 11% for inter-day relative error (%). Finally, the method applicability was examined for the determination of nonsteroidal anti-inflammatory drugs in saliva samples, and good relative recoveries were obtained within the range 86.5 to 95.2%. As a result, the introduced method can be applied as a suitable alternative to measuring nonsteroidal anti-inflammatory drugs in biological fluids. Graphical abstract A surface-modified Ce-doped ZnAl LDH thin film was synthesized on the inner surface of an Al tube and applied for in-tube stir bar sorptive extraction of NSAIDs in saliva.

Micro solid phase extraction of parabens from breast milk samples using Mg-Al layered double hydroxide functionalized partially reduced graphene oxide nanocomposite.

In this study, a magnesium-aluminum layered double hydroxide coated on graphene oxide nanosheets was synthesized. It was successfully applied as an effective medium for determination of the parabens in human breast milk samples using micro solid phase extraction by packed sorbent (in spinal syringe format) followed by HPLC-UV. Effective parameters were optimized by central composite design. Under the optimal conditions, figures of merit of the developed method were obtained in which the limits of detection were found between 3.0 and 5.0 µg L-1. The calibration plots were linear in the range of 10-1000 µg L-1. Intra- and inter-day RSD% (n = 3) at two concentration levels of 25 and 250 µg L-1 varied between 4.2 and 9.5%. The relative recovery values for the spiked breast milk samples were in the acceptable range of 87.2-104.4%. Accordingly, the proposed method exhibits proper sensitivity, good repeatability, and acceptable applicability for the determination of parabens in complex matrices.

Porphyrin-functionalized graphene oxide sheets: An efficient nanomaterial for micro solid phase extraction of non-steroidal anti-inflammatory drugs from urine samples.

In this work, porphyrin-functionalized graphene oxide nanosheets (GO@meso-tetrakis(4-hydroxyphenyl)porphyrin) were synthesized and employed as the sorbent. Porphyrins owing to their unique structures and tunable terminal functional groups are expected to be promising media for extraction of the desired analytes. Also, GO with a high specific surface area has exhibited good potential for the extraction purposes. Inspired by these intriguing properties, the combination of GO and porphyrin can benefit both of these amazing features. The synthesized sorbent was utilized for micro solid phase extraction of non-steroidal anti-inflammatory drugs followed by HPLC-UV. Optimization of the experimental factors including sorbent amount, sample pH, sample and eluent flowrates, eluent volume, and the number of desorption cycles were performed with the aid of central composite design. Under the optimal conditions, the calibration curves were linear within the range of 2.0-600 ng mL-1 and limits of detection were found between 0.5-2.0 ng mL-1. The preconcentration factors and absolute recoveries were obtained in the range of 4.80-9.79 and 29%-59%, respectively. The matrix effect for the urine samples varied between 81.9%-91.6% at two concentrations of 50 and 300 ng mL-1, respectively. Intra- and inter-day RSD% (n = 3) of the spiked urine samples at three level concentrations of 25, 100, and 300 ng mL-1 were less than 10%. The relative recoveries of the urine samples were calculated in the range of 85.2-98.6%. Eventually, the method exhibits proper sensitivity, excellent repeatability, high reusability, and acceptable precision and accuracy.