Publications by authors named "Shahram Seidi"

75 Publications

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

Talanta 2021 Jul 9;229:122273. Epub 2021 Mar 9.

Department of Chemistry, College of Science, Salahaddin University-Erbil, 44001, Kurdistan Region, Iraq; Department of Pharmacognosy, Faculty of Pharmacy, Tishk International University-Erbil, 44001, Kurdistan Region, Iraq.

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.
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http://dx.doi.org/10.1016/j.talanta.2021.122273DOI Listing
July 2021

Preparation of Polyacrylonitrile/Ni-MOF electrospun nanofiber as an efficient fiber coating material for headspace solid-phase microextraction of diazinon and chlorpyrifos followed by CD-IMS analysis.

Food Chem 2021 Jul 9;350:129242. Epub 2021 Feb 9.

Department of Analytical Chemistry and Pollutants, Faculty of Chemistry and Petroleum Sciences, Shahid Beheshti University, Tehran, Iran.

Herein, an electrospun polyacrylonitrile/nickel-based metal-organic framework nanocomposite (PAN/Ni-MOF) coating on a stainless steel wire was synthesized and employed as a novel nanosorbent for headspace solid-phase microextraction (HS-SPME) of organophosphorus pesticides (OPPs), diazinon (DIZ), and chlorpyrifos (CPS) from the diverse aqueous media followed by corona discharge ion mobility spectrometry (CD-IMS). Under the optimum experimental conditions, the calibration plots were linear in the range of 1.0-250.0 ng mL for DIZ and 0.5-300.0 ng mL for CPS with r > 0.999. The detection limits (S/N = 3) were 0.3 and 0.2 ng mL for DIZ and CPS, respectively. The intra-day relative standard deviations (RSDs%) (n = 5) at the concentration levels of 20.0, 40.0, and 100.0 ng mL were ≤ 5.2%. To investigate the extraction efficiency, PAN/Ni-MOF was employed to analyze various juice samples, including orange, apple, and grape juices, and in three water samples where it led to good recoveries ranged between 87% and 98%.
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http://dx.doi.org/10.1016/j.foodchem.2021.129242DOI Listing
July 2021

Microfluidic-enabled versatile hyphenation of electromembrane extraction and thin film solid phase microextraction.

Talanta 2021 Mar 5;224:121864. Epub 2020 Nov 5.

Department of Analytical Chemistry, Faculty of Chemistry, K. N. Toosi University of Technology, Tehran, Iran.

In the present study, a versatile combination of electromembrane extraction (EME) with thin film solid phase microextraction (TF-SPME) was introduced using a microfluidic chip device. The device consisted of two single channels on two separate layers. The upper channel was dedicated to donor phase flow pass, while the beneath channel was used as a reservoir for stagnant acceptor solution. A slide of fluorine doped tin oxide (FTO) was accommodated in the bottom of the acceptor phase channel. A thin layer of polyaniline was electrodeposited on the FTO surface to achieve the required thin film for TF-SPME. A stainless-steel wire was embedded in the donor phase channel and another wire was also attached to the FTO surface. The channels were separated by a piece of polypropylene membrane impregnated with 1-octanol and the whole chip was fixed with bolts and nuts. The driving force for the extraction was an 8 V direct current (DC) voltage applied across the supported liquid membrane (SLM). Under the influence of the electrical field, analytes immigrated from sample towards the acceptor phase and then adsorbed on the thin film of the solid phase. Finally, the analytes were desorbed by successive movement of a desorption solvent in the acceptor phase channel followed by injection of the desorption solution to HPLC-UV. The applicability of the proposed device was demonstrated by the determination of four synthetic food dyes: Amaranth, Ponceau 4R, Allura Red, and Carmoisine, as the model analytes. The effective parameters on the efficiency of the both EME and TF-SPME were investigated. Under the optimized conditions, the microchip provided low LODs (1-10 μg L), and a wide linear dynamic range of 10-1000 μg L for all analytes. The system also offered RSD values lower than 5.5% and acceptable reusability of the thin film for multiple extractions.
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http://dx.doi.org/10.1016/j.talanta.2020.121864DOI Listing
March 2021

Pipette-tip SPE based on Graphene/ZnCr LDH for Pb(II) analysis in hair samples followed by GFAAS.

Anal Biochem 2021 01 15;612:113949. Epub 2020 Sep 15.

Department of Chemistry, Faculty of Science, University of Qom, Qom, Iran.

In this work, a nanocomposite of ZnCr layered double hydroxide (ZnCr LDH) and graphene oxide (GO) was successfully assembled. An efficient pipette-tip solid-phase extraction (PT-SPE) based on GO/ZnCr LDH followed by GFAAS analysis was used for to preconcentrate Pb(II) in hair samples. Hair samples were treated using acid digestion to make the solid samples suitable for performing the PT-SPE procedure and decrease the interactions between Pb(II) ions and the sample matrix. The sorbent was characterized by FT-IR, SEM, TEM, EDX, elemental mapping, and XRD. Effective extraction parameters were thoroughly investigated. Under the best conditions, the calibration plot was linear within the range of 0.5-15 ng mL (R = 0.991). Preconcentration factor (PF) of 10 and absolute recovery (%) of 100% were obtained. LOD and LOQ were found to be 0.1 μg g and 0.5 μg g, respectively. The intra-day and inter-day precisions (n = 3) at the concentrations of 2.0 and 10 ng mL were less than 6.8% and 12.5%, respectively. Finally, the method efficiency was investigated for the analysis of Pb(II) in hair samples, and good relative recoveries (RR%) were obtained within the range of 92%-104%.
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http://dx.doi.org/10.1016/j.ab.2020.113949DOI Listing
January 2021

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

Anal Chim Acta 2020 Sep 30;1131:90-101. Epub 2020 Jul 30.

Department of Analytical Chemistry, K.N. Toosi University of Technology, Tehran, Iran.

Herein, we applied a simple electrosynthesis process to deposit nickel-iron layered double hydroxides (NiFe LDH) on the surface of copper hydroxide (Cu(OH)) 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)-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. 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 for ketoconazole, 8.0-1000 ng mL for clotrimazole, and 15-1000 ng mL 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.
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http://dx.doi.org/10.1016/j.aca.2020.07.053DOI Listing
September 2020

In situ electrosynthesis of a copper-based metal-organic framework as nanosorbent for headspace solid-phase microextraction of methamphetamine in urine with GC-FID analysis.

Mikrochim Acta 2020 09 4;187(10):548. Epub 2020 Sep 4.

Department of Chemistry, Faculty of Physics and Chemistry, Alzahra University, Tehran, Iran.

For the first time, a fiber coating based on copper metal-organic framework was fabricated on an anodized stainless steel wire by an in situ electrosynthesis approach. The fiber was used for the preconcentration and determination of methamphetamine by headspace solid-phase microextraction followed by gas chromatography-flame ionization detection. The electrosynthesis of the fiber coating was performed under a constant potential of - 1.7 V by controlling the electrogeneration of OH in a solution containing sodium nitrate as the probase, 1,2,4,5-benzenetetracarboxylate acid as the ligand and copper nitrate as the cation source. The coating was characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The effective parameters on the electrosynthesis, extraction, and desorption processes were thoroughly optimized. Under the optimized conditions, metamphetamine (MAP) was quantified over a linear range of 0.90-1000.0 ng mL with R > 0.997. A limit of detection of 0.1 ng mL was achieved, and intra- and inter-day relative standard deviations were found within the range 3.0-4.4% and 2.8-3.9%, respectively. Finally, the method was successfully applied to determination of MAP in urine samples with good recoveries in the range 85.0-102.5%. Graphical abstract Schematic representation of the in-situ electrochemical synthesis of a Cu-based metal-organic framework and its application in a headspace SPME procedure for the measuring methamphetamine in urine samples followed by GC-MS analysis.
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http://dx.doi.org/10.1007/s00604-020-04535-wDOI Listing
September 2020

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.

Mikrochim Acta 2020 08 29;187(9):528. Epub 2020 Aug 29.

Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, Tehran, Iran.

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. Calibration plots were linear within the range 10-1000 ng mL (R > 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 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.
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http://dx.doi.org/10.1007/s00604-020-04489-zDOI Listing
August 2020

Preparation of electrospun polyacrylonitrile/Ni-MOF-74 nanofibers for extraction of atenolol and captopril prior to HPLC-DAD.

Mikrochim Acta 2020 08 22;187(9):508. Epub 2020 Aug 22.

Faculty of Chemistry and Petroleum Sciences, Department of Analytical Chemistry and Pollutants, Shahid Beheshti University, G.C., Evin, Tehran, Iran.

Electrospun nanofibers of polyacrylonitrile/Ni-metal-organic framework 74 (PAN/Ni-MOF-74) were prepared and utilized as a novel sorbent for spin-column micro-solid-phase extraction (SC-μSPE) of atenolol (ATN) and captopril (CAP). The electrospun nanofibers were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. Ni-MOF-74 nanoparticles in the polymeric network of polyacrylonitrile considerably enhance the extraction efficiency of the electrospun sorbent due to providing hydrophobic, hydrogen bonding, and π-π interactions with the target analytes. The entire procedure, including sample loading, washing, and eluting of the target analytes was performed by centrifugation of the spin column. The extracted analytes were then quantified by high-performance liquid chromatography with a diode array detector. Various parameters affecting extraction efficiency were optimized using the one-variable-at-a-time method. Under optimum conditions, the calibration plots were linear in the range 0.5-500 ng mL for ATN and 0.3-500 ng mL for CAP with r > 0.999. Limits of detection of 0.15 and 0.13 ng mL were obtained for ATN and CAP, respectively. The intra-assay relative standard deviation for five replicate measurements was ≤ 7.8. The relative recoveries for both drugs were within the range 82.6-98.9%. The applicability of the method was successfully investigated for measuring the target drugs in biological fluids and wastewater. The results indicate proper accuracy and analytical performance of the proposed method. Graphical abstract Schematic presentation of electrospun nanofibers of polyacrylonitrile/Ni-metal-organic framework 74 (PAN/Ni-MOF-74) which are used as the sorbent for spin-column microextraction (SC-μSPE) of atenolol (ATN) and captopril (CAP) prior to HPLC-DAD analysis.
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http://dx.doi.org/10.1007/s00604-020-04483-5DOI Listing
August 2020

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.

J Chromatogr A 2020 Sep 13;1628:461486. Epub 2020 Aug 13.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, Tehran, Iran.

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, with a regression coefficient of 0.9972. The limits of detection (LOD) and quantification (LOQ) were found to be 0.1 ng mL and 0.3 ng mL, respectively. Intra-day and inter-day RSDs% for three replicate measurements of naphthalene at the concentration of 10 ng mL 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.
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http://dx.doi.org/10.1016/j.chroma.2020.461486DOI Listing
September 2020

Quantitative determination of trace phenazopyridine in human urine samples by hyphenation of dispersive solid-phase extraction and liquid-phase microextraction followed by gas chromatography/mass spectrometry analysis.

J Sep Sci 2020 Jul 4;43(14):2897-2904. Epub 2020 Jun 4.

Department of Analytical Chemistry, Faculty of Chemistry, K. N. Toosi University of Technology, Tehran, Iran.

Magnetic dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction coupled with gas chromatography/mass spectrometry was applied for the quantitative analysis of phenazopyridine in urinary samples. Magnetic dispersive solid-phase extraction was carried out using magnetic graphene oxide nanoparticles modified by poly(thiophene-pyrrole) copolymer. The eluting solvent of this step was used as the disperser solvent for the dispersive liquid-liquid microextraction procedure. To reach the maximum efficiency of the method, effective parameters including sorbent amount, adsorption time, type and volume of disperser and extraction solvents, pH of the sample solution, and ionic strength as well as desorption time, and approach were optimized, separately. Characterization of the synthesized sorbent was studied by utilizing infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analysis. Calibration curve was linear in the range of 0.5-250 ng/mL (R  = 0.9988) with limits of detection and quantification of 0.1 and 0.5 ng/mL, respectively. Intra- and interday precisions (RSD%, n = 3) of the method were in the range of 4.6-5.4% and 4.0-5.5%, respectively, at three different concentration levels. Under the optimal condition, this method was successfully applied for the determination of phenazopyridine in human urine samples. The relative recoveries were obtained in the range of 85.0-89.0%.
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http://dx.doi.org/10.1002/jssc.202000055DOI Listing
July 2020

Polyacrylonitrile/MIL-53(Fe) electrospun nanofiber for pipette-tip micro solid phase extraction of nitrazepam and oxazepam followed by HPLC analysis.

Mikrochim Acta 2020 01 31;187(2):152. Epub 2020 Jan 31.

Faculty of Chemistry and Petroleum Sciences, Department of Analytical Chemistry and Pollutants, Shahid Beheshti University, G.C., Evin, Tehran 19839-69411, Iran.

Nanofibers were prepared from a nanocomposite consisting of polyacrylonitrile and a metal-organic framework of type MIL-53(Fe) by electrospinning. They are shown to be a viable sorbent for pipette-tip solid-phase extraction for the extraction of the benzodiazepine drugs nitrazepam and oxazepam. The nanofibers were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The effects of sample pH value and volume, composition, and amount of electrospun nanofibers, the number of adsorption cycles and the type and volume of the eluent were optimized. Following extraction the drugs were quantified by HPLC. Under the optimized conditions, response is linear for both drugs in the 5.0-1000 ng mL concentration range. The limits of detection for oxazepam and nitrazepam are 1.5 and 2.5 ng mL, respectively, and the relative standard deviations at the levels of 50, 100 and 250 ng mL (for n = 3) are ≤7.6%. The method was successfully applied for determination of drugs in spiked wastewater and biological fluids. Graphical abstractSchematic representation of polyacrylonitrile/MIL-53(Fe) composite nanofiber synthesis by electrospinning, and the use of them as the sorbent in pipette-tip microsolid-phase extraction (PT-μSPE) for the preconcentration of Nitrazepam and Oxazepam before HPLC-DAD analysis.
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http://dx.doi.org/10.1007/s00604-020-4112-3DOI Listing
January 2020

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

Food Chem 2020 Jun 17;314:126223. Epub 2020 Jan 17.

Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, Tehran, Iran.

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. The calibration plots were linear in the range of 10-1000 µg L. Intra- and inter-day RSD% (n = 3) at two concentration levels of 25 and 250 µg L 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.
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http://dx.doi.org/10.1016/j.foodchem.2020.126223DOI Listing
June 2020

Electrospun NiFe layered double hydroxide/Nylon 6 composite nanofibers as a sorbent for micro solid phase extraction by packed sorbent of non-steroidal anti-inflammatory drugs in human blood.

J Chromatogr A 2020 Mar 18;1614:460718. Epub 2019 Nov 18.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran, Iran.

In the present work, NiFe layered double hydroxide (LDH)/Nylon 6 composite nanofibers were prepared by electrospinning method and used as a new sorbent for the extraction and measurement of non-steroidal anti-inflammatory drugs (naproxen, mefenamic acid, and diclofenac) in whole blood samples. The method is based on micro solid phase extraction (µSPE) by packed sorbent followed by HPLC-UV analysis. Effective parameters on the extraction efficiency were optimized using a central composite design (CCD). In order to characterize the sorbent, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) and elemental mapping were applied. The method was fully validated based on linearity, limits of detection (LOD) and quantification (LOQ), precision, and recovery. Under the optimal conditions, LOD values were found to be 25 ng mL for naproxen and diclofenac and 15 ng mL for mefenamic acid. A seven-point calibration curve was obtained in the range of 75-2000 ng mL for naproxen and diclofenac and 50-2000 for mefenamic acid. The method showed good linearity with coefficients of determination, r> 0.9962, for the three drugs. In the entire analytical range, the relative standard deviations (RSD%) were less than 8.1%. Finally, the efficiency of the method was investigated for the analysis of the target analytes in human blood samples, and the recoveries were obtained in the range of 90.7-109.8%.
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http://dx.doi.org/10.1016/j.chroma.2019.460718DOI Listing
March 2020

Haas in grilled meat: Determination using an advanced lab-on-a-chip flat electromembrane extraction coupled with on-line HPLC.

Food Chem 2020 May 11;311:125876. Epub 2019 Nov 11.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, Tehran, Iran.

In this research, a new design of channels in a lab-on-a-chip device with flat electromembrane extraction (LOC-FLEME) was fabricated. The latter microfluidic device was successfully used for the determination of 2-amino-3-methyl imidazo[4-5-f]quinolone (IQ), 2-amino-3, 8-dimethlylimidazo[4, 5-f]quinolone (MeIQ), 2-amino-3,4- dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine (PhIP) in grilled meat, by on-line coupling of LOC-FLEME to an HPLC system. Important parameters in extraction process were optimized. The calibration curve was linear over the range of 5-1000 ng g with a correlation coefficient higher than 0.9991. The relative recoveries were between 95 and 98% at three concentration levels. The relative standard deviations were 4.1 to 6.0%. The limits of detection were 1.4, 0.9, 1.7 and 1.3 ng g for PhIP, IQ, MeIQ and MeIQx, respectively. Sums of 4HAAs concentrations for different grilled meat samples were 2.75-6.17 ng g.
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http://dx.doi.org/10.1016/j.foodchem.2019.125876DOI Listing
May 2020

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

J Chromatogr A 2019 Dec 19;1607:460387. Epub 2019 Jul 19.

Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, Tehran, Iran.

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 and limits of detection were found between 0.5-2.0 ng mL. 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, respectively. Intra- and inter-day RSD% (n = 3) of the spiked urine samples at three level concentrations of 25, 100, and 300 ng mL 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.
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http://dx.doi.org/10.1016/j.chroma.2019.460387DOI Listing
December 2019

Nickel-iron layered double hydroxide nanostructures for micro solid phase extraction of nonsteroidal anti-inflammatory drugs, followed by quantitation by HPLC-UV.

Mikrochim Acta 2019 04 23;186(5):297. Epub 2019 Apr 23.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran, Postal Code 15418-49611, Iran.

Layered double hydroxides (LDHs) of nickel and iron were hydrothermally prepared by co-precipitation using urea hydrolysis. The Ni-Fe LDH nanostructures were characterized by X-ray diffraction, FT-IR spectroscopy, scanning electron microscopy, thermogravimetric and energy dispersive X-ray analysis. The LDHs are shown to be a viable sorbent for micro solid phase extraction by packed sorbent of the nonsteroidal anti-inflammatory drugs (NSAIDs) diclofenac, ibuprofen, mefenamic acid and naproxen from human urine. Adsorption and desorption parameters were optimized using a central composite design. Following desorption with a methanol/water mixture (95:5 v:v) containing 0.1% formic acid, the NSAIDs were quantified by HPLC with UV detection. Under the optimal conditions, response is linear in the 10-1000 ng.mL NSAID concentration range. Limits of detection and intra-day and inter-day RSDs are <10 ng.mL and 10.2%, respectively. The method was successfully applied to the determination of NSAIDs in some positive human urine samples. Relative recoveries from spiked samples range from 94.8 to 113%. Graphical abstract Layered double hydroxides of nickel and iron were synthesized and packed in a spinal syringe for micro solid phase extraction of non-steroidal anti-inflammatory drugs.
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http://dx.doi.org/10.1007/s00604-019-3419-4DOI Listing
April 2019

Synthesis and characterization of polyamide-graphene oxide-polypyrrole electrospun nanofibers for spin-column micro solid phase extraction of parabens in milk samples.

J Chromatogr A 2019 Aug 8;1599:25-34. Epub 2019 Apr 8.

Department of Chemistry, Tarbiat Modares University, Tehran, Iran.

In the present study, an electrospun composite of polyamide-graphene oxide-polypyrrole was synthesized. The characterization of the synthesized material was accomplished using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FT-IR). FESEM images showed uniform and beadles nanofibers. The composite was employed as a novel sorbent for spin-column micro solid phase extraction to determine parabens in milk samples. Addition of graphene oxide and polypyrrole into the polymeric network of polyamide significantly improves the extraction efficiency of the electrospun sorbent due to providing the possibility of various interactions with the target analytes such as hydrogen bonding, hydrophobic and π-π stacking. All effective parameters on the efficiency of both adsorption and desorption steps were optimized. These parameters were pH of sample solution (5.0), sorbent amount (20 mg), type and volume of desorption solvent (200 μL of methanol), number of cycles (7 and 14) and centrifugation speed (600 and 500 rpm) of both adsorption and desorption steps. Under the optimal conditions, the calibration plots were linear within the range of 10-1000, 15-1000, and 20-1000 ng mL for methyl paraben, ethyl paraben and propyl paraben, respectively. Limits of detection were obtained lower than 7.0 ng mL by HPLC-UV. Intra- and inter-assay relative standard deviations were less than 8.6% and 5.8%, respectively. Finally, the method was successfully applied for determination of parabens in some milk samples and good recoveries were obtained within the range of 81.7-97.8%. The results demonstrated good efficiency of the synthesized electrospun composite nanofibers as the packing material for spin-column micro solid phase extraction.
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http://dx.doi.org/10.1016/j.chroma.2019.04.014DOI Listing
August 2019

Imidazolium-based mesoporous organosilicas with bridging organic groups for microextraction by packed sorbent of phenoxy acid herbicides, polycyclic aromatic hydrocarbons and chlorophenols.

Mikrochim Acta 2019 03 13;186(4):239. Epub 2019 Mar 13.

Department of Anatomy and Cell Biology and Facility for Electron Microscopy Research, McGill University, Montreal, Quebec, H3A2A7, Canada.

The authors describe the preparation of two kinds of periodic mesoporous organosilicas (PMOs). The first kind is monofunctional and has a bridged alkyl imidazolium framework (PMO-IL). The other is a two-dimensional (2D) hexagonal bifunctional periodic mesoporous organosilica (BFPMO) with bridged IL-phenyl or -ethyl units. The CPMOs were utilized as highly sensitive and stable sorbents for microextraction by packed sorbent. The materials were characterized by SEM, TEM, FT-IR, and N adsorption-desorption analysis. The adsorption capacities of the sorbents were investigated by using phenoxy acid herbicides as model analytes. The effects of bifunctionality and type of additional surface groups (phenyl or ethyl) on the efficiency of the extraction is emphasized. Three kinds of environmental contaminants, viz. phenoxy acid herbicides (CPAs), polycyclic aromatic hydrocarbons and chlorophenols were then studied with respect to their extraction by the sorbents. The interactions between the CPAs and the sorbents were evaluated by pH-changing processes to explore the interactions that play a major role. The selectivity of the sorbents was investigated by extraction of other types of analytes of with various polarity and charge. The BFPMOs display the typical good chemical stability of silica materials. The extraction properties are much better compared to commercial silicas. This is assumed to be due to the highly ordered mesoporous structures and the different types of probable interactions with analytes. The performance of the method was evaluated by extraction of CPAs as model analytes from aqueous samples, and quantification by GC with FID detection. Under optimized conditions, low limits of detection (0.1-0.5 μg.L) and a wide linearity (0.5-200 μg.L) were obtained. The method was applied to the trace analysis of CPAs in farm waters and rice samples. Graphical abstract Monofunctional periodic mesoporous organosilica with bridged alkyl imidazolium frameworks and bi-functional periodic mesoporous organosilica containing bridged ionic liquids and phenyl or -ethyl, have been successfully synthesized and utilized in microextractions by packed sorbent sorbents.
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http://dx.doi.org/10.1007/s00604-019-3355-3DOI Listing
March 2019

Polydopamine-functionalized magnetic iron oxide for the determination of trace levels of lead in bovine milk.

Anal Biochem 2019 04 25;570:5-12. Epub 2019 Jan 25.

Faculty of Chemistry, K.N. Toosi University of Technology, Tehran, Iran. Electronic address:

In this work, a novel sorbent based on polydopamine-functionalized magnetic ferric oxide (FeO) was synthesized and applied for dispersive solid phase extraction of Pb(II) in bovine milk samples. The extracts were analyzed by flame atomic absorption spectrometry (FAAS). The sorbent was characterized with different analytical techniques (XRD, FT-IR, SEM, TEM, VSM and EDX). To reach the maximum extraction efficiency of Pb(II), some effective parameters on both adsorption and desorption steps were optimized with the aid of central composite design and response surface methodology. Under the optimal conditions, the method provided an enhancement factor of 40.5 corresponding to the absolute recovery of 81%. LOD and LOQ were found as 0.13 and 0.43 ng mL, respectively. The calibration curve was linear over the concentration range of 3.0-300 ng mL (R = 0.9957). The intra and inter-day precisions (RSD%) of the method were calculated as 3.2% and 5.6%, respectively. Finally, the method was successfully applied for the determination of Pb(II) in different bovine milk samples. The Pb(II) content in one of the investigated milk samples was found to exceed the maximum permissible limit (20 μg L) set by Codex Alimentarius Commission. The relative recoveries were obtained within the range of 86.5-93.6.
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http://dx.doi.org/10.1016/j.ab.2019.01.008DOI Listing
April 2019

A promising design of microfluidic electromembrane extraction coupled with sensitive colorimetric detection for colorless compounds based on quantum dots fluorescence.

Talanta 2019 Mar 18;194:298-307. Epub 2018 Oct 18.

Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, Tehran, Iran.

In the present study, a microfluidic platform was exploited for electromembrane extraction. For device integration as a lab-on-a-chip system, the detection step was carried out by a colorimetric method based on fluorescence quenching of quantum dots. The model analyte was transferred under a pulsed applied electrical field across a polypropylene membrane, impregnated with 1-Octanol, into a final aqueous acceptor phase. The obtained acceptor phase was added into a solution containing CdTe quantum dots. Quenching of the quantum dots was tracked by analyzing the main three color components of red, green, and blue in different concentration levels of the analyte. All effective parameters on the extraction efficiency, fluorescence detection, and synthesis of quantum dots were optimized. Under the optimal conditions, the detection was accomplished by three different detection methods including HPLC-UV, spectrofluorometric detection, as well as colorimetry detection via a smartphone. Calibration curves were linear in the range of 2.0-500 µg L for LC-UV, 30-2500 µg L for fluorescence detection, and 2.5-20 µg mL for image analysis. Inter- and intra-assay relative standard deviations were less than 10.1% in all detection modes.
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http://dx.doi.org/10.1016/j.talanta.2018.10.046DOI Listing
March 2019

Miniaturized sample preparation methods for saliva analysis.

Bioanalysis 2019 Jan 12;11(2):119-148. Epub 2018 Dec 12.

Department of Chemistry, Faculty of Science, Qom University, Qom, Iran.

Saliva, as the first body fluid encountering with the exogenous materials, has good correlation with blood and plays an important role in bioanalysis. However, saliva has not been studied as much as the other biological fluids mainly due to restricted access to its large volumes. In recent years, there is a growing interest for saliva analysis owing to the emergence of miniaturized sample preparation methods. The purpose of this paper is to review all microextraction methods and their principles of operation. In the following, we examine the methods used to analyze saliva up to now and discuss the potential of the other microextraction methods for saliva analysis to encourage research groups for more focus on this important subject area.
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http://dx.doi.org/10.4155/bio-2018-0160DOI Listing
January 2019

Rapid ultrasound-assisted dispersive solid-phase extraction of nonsteroidal anti-inflammatory drugs in urine using oleic acid functionalized magnetic graphene oxide.

J Sep Sci 2018 Dec 25;41(23):4370-4378. Epub 2018 Oct 25.

Faculty of Chemistry, Department of Analytical Chemistry, K. N. Toosi University of Technology, Tehran, Iran.

We describe an ultrasound-assisted magnetic dispersive solid-phase extraction based on oleic acid functionalized magnetic graphene oxide followed by high-performance liquid chromatography with ultraviolet detection. The method was applied for the simultaneous determination of ibuprofen, diclofenac, naproxen, and mefenamic acid in urine. The application of sonication led to the good dispersion of the sorbent, and consequently, significant shortened the extraction time. The sorbent was successfully characterized by different techniques. The influence of the adsorption parameters was optimized using a rotational central composite design. In order to improve desorption efficiency, parameters such as type and volume of the eluent and sonication time were investigated and optimized through a one variable at a time method. Under the optimum conditions, limits of detection and precision were between 3.0-25 ng/mL (n = 5) and 3.2-7.1%, respectively. The preconcentration factors were found to be 74 for naproxen, 76 for diclofenac, 80 for ibuprofen, and 66 for mefenamic acid corresponding to the absolute recovery within the range of 82.5-100%. Finally, the proposed method was successfully applied for simultaneous determination of target analytes in human urine samples. The relative recovery was within the range of 91.4-113.3%, indicating the good reliability and accuracy of the method.
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http://dx.doi.org/10.1002/jssc.201800663DOI Listing
December 2018

Dispersed Solidified Fine Droplets Based on Sonication of a Low Melting Point Deep Eutectic Solvent: a Novel Concept for Fast and Efficient Determination of Cr(VI) in Urine Samples.

Biol Trace Elem Res 2019 Apr 24;188(2):353-362. Epub 2018 Jul 24.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran, Iran.

Cr(VI) has carcinogenic effects, so determination of trace amount of chromium in human body such as urine has a great deal of importance. In this work, a novel microextraction method was developed based on solidification of dispersed fine droplets (SDFD) of a low melting point deep eutectic solvent (DES), produced with the aid of sonication, for fast and efficient determination of Cr(VI) in urine samples. Cr(VI) contents of the human urine samples were first complexed using 1,5-diphenylcarbazone at pH ≈ 2.0 and then extracted by the method. A cloudy solution was achieved by the sonication of a microliter volume of a new water-immiscible DES consisting of benzyltriphenylphosphonium bromide (BTPPB) and phenol. Low freezing point of DES makes it possible to use simple, precise, and fast collection of the extraction phase by solidification and the subsequent centrifugation. Finally, the sedimented phase was diluted with methanol and analyzed by electrothermal atomic absorption spectrometry (ETAAS). The influences of the main factors on the efficiency of the procedure were investigated by a four-factor central composite design (CCD). Under the optimum conditions, the calibration curve was linear within the range of 10-1000 ng L. The intra- and inter-day RSD% values of 2.6 and 4.7% were obtained at the concentration of 50.0 ng L, respectively. The limits of detection (LOD) and quantification (LOQ) were calculated as 2.0 and 7.0 ng L, respectively. Moreover, compared to the other approaches, the proposed method presented better or comparable analytical performance and provided accurate, precise, and reliable results for trace analysis of Cr(VI) in urine samples.
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http://dx.doi.org/10.1007/s12011-018-1438-3DOI Listing
April 2019

A silica fiber coated with a ZnO-graphene oxide nanocomposite with high specific surface for use in solid phase microextraction of the antiepileptic drugs diazepam and oxazepam.

Mikrochim Acta 2018 06 2;185(6):312. Epub 2018 Jun 2.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, Tehran, 19697 64499, Iran.

A novel ZnO-graphene oxide nanocomposite was prepared and is shown to be a viable coating on fused silica fibers for use in solid phase microextraction (SPME) of diazepam and oxazepam from urine, this followed by thermal desorption and gas chromatographic quantitation using a flame ionization detector. A central composite design was used to optimize extraction time, salt percentage, sample pH and desorption time. Limits of detection are 0.5 μg·L for diazepam and 1.0 μg·L for oxazepam. Repeatability and reproducibility for one fiber (n = 4), expressed as the relative standard deviation at a concentration of 50 μg·L, are 8.3 and 11.3% for diazepam, and 6.7 and 10.1% for oxazepam. The fiber-to-fiber reproducibility is <17.6%. The calibration plots are linear in the 5.0-1000 μg·L diazepam concentration range, and from 1.0-1000 μg·L in case of oxazepam. The fiber for SPME has high chemical and thermal stability (even at 280 °C) after 50 extractions, and does not suffer from a reduction in the sorption capacity. Graphical abstract A hydrothermal method was introduced for preparation of ZnO- GO nano composite on a fused silica fiber as solid phase microextraction with high mechanical, chemical stability and long service life.
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http://dx.doi.org/10.1007/s00604-018-2850-2DOI Listing
June 2018

Approach for Downscaling of Electromembrane Extraction as a Lab on-a-Chip Device Followed by Sensitive Red-Green-Blue Detection.

Anal Chem 2018 07 29;90(14):8478-8486. Epub 2018 Jun 29.

Department of Chemistry , Abdul Wali Khan University , Mardan , Khyber Pakhtunkhwa Pakistan , 23200.

A design of electromembrane extraction (EME) as a lab on-a-chip device was proposed for the extraction and determination of phenazopyridine as the model analyte. The extraction procedure was accomplished by coupling EME and packing a sorbent. The analyte was extracted under the applied electrical field across a membrane sheet impregnated by nitrophenyl octylether (NPOE) into an acceptor phase. It was followed by the absorption of the analyte on strong cation exchanger as a sorbent. The designed chip contained separate spiral channels for donor and acceptor phases featuring embedded platinum electrodes to enhance extraction efficiency. The selected donor and acceptor phases were 0 mM HCl and 100 mM HCl, respectively. The on-chip electromembrane extraction was carried out under the voltage level of 70 V for 50 min. The analysis was carried out by two modes of a simple red-green-blue (RGB) image analysis tool and a conventional HPLC-UV system. After the absorption of the analyte on the solid phase, its color changed and a digital picture of the sorbent was taken for the RGB analysis. The effective parameters on the performance of the chip device, comprising the EME and solid phase microextraction steps, were distinguished and optimized. The accumulation of the analyte on the solid phase showed excellent sensitivity and a limit of detection (LOD) lower than 1.0 μg L achieved by an image analysis using a smartphone. This device also offered acceptable intra- and interassay RSD% (<10%). The calibration curves were linear within the range of 10-1000 μg L and 30-1000 μg L ( r > 0.9969) for HPLC-UV and RGB analysis, respectively. To investigate the applicability of the method in complicated matrixes, urine samples of patients being treated with phenazopyridine were analyzed.
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http://dx.doi.org/10.1021/acs.analchem.8b01224DOI Listing
July 2018

Magnetic nanocomposite of chitosan-Schiff base grafted graphene oxide for lead analysis in whole blood.

Anal Biochem 2018 07 18;553:28-37. Epub 2018 May 18.

Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, Tehran, Iran.

A new Schiff base grafted graphene oxide-magnetic chitosan was utilized as a novel sorbent for extraction and quantification of lead ion in blood samples via dispersive magnetic solid phase extraction. The prepared nanocomposite sorbent was characterized by SEM, TEM, FT-IR, XRD, VSM and EDX and the quantification analysis was performed by microsampling flame atomic absorption spectrometry. The important parameters on the extraction efficiency were thoroughly optimized by means of experimental design. Under the optimized conditions, an aliquot of 50 mL of sample (pH 6.3) was extracted utilizing 60 mg of magnetic nanoparticles during 30 min. The sorbent was afterward desorbed using 1.0 mL of 0.8 mol L HNO under fierce vortex for 6 min. A preconcentration factor of 20 and an absolute recovery of 40% were provided by the proposed method. The limits of detection (3S/N) and quantification (10 S/N) were 0.06 ng mL and 2.0 ng mL, respectively. An excellent linearity was achieved within the range of (10-800) ng mL and the regression coefficient was 0.9903. The intra- and inter-day RSDs% were found to be 1.8% and 7.0%, respectively. Furthermore, the method was applied for analysis of blood samples and good accuracies within the range of 97%-108% were obtained.
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http://dx.doi.org/10.1016/j.ab.2018.05.018DOI Listing
July 2018

A novel N,N'-bis(acetylacetone)ethylenediimine functionalized silica-core shell magnetic nanosorbent for manetic dispersive solid phase extraction of copper in cereal and water samples.

Food Chem 2018 May 27;249:30-37. Epub 2017 Dec 27.

Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, Tehran, Iran.

Determination of heavy metals at trace levels has a great deal of importance due to their undesirable effects on human life. In this study, N,N'-bis (acetyl acetone) ethylenediimine (FeO@SiO-EDN) was synthesized and applied for dispersive solid phase extraction of copper in water and cereal samples followed by FAAS. Sorbent characterization was investigated by SEM, FT-IR, EDX and VSM. The effective parameters were optimized using a central composite design. Under the optimal conditions, LOD (S/N = 3) and LOQ, preconcentration factor and RSD% were found to be 1.5 ng mL, 4.0 ng mL, 13 and 2.3%, respectively. The calibration curve was linear within the range of 4.0-175 ng mL with r > 0.998. Relative recoveries were achieved within the range of 90.0-95.0%. With thanks of the good resulting analytical performance in this work, the proposed method can be applied as a suitable alternative for trace analysis of copper.
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http://dx.doi.org/10.1016/j.foodchem.2017.12.085DOI Listing
May 2018

Quantitative analysis of clonidine and ephedrine by a microfluidic system: On-chip electromembrane extraction followed by high performance liquid chromatography.

J Chromatogr B Analyt Technol Biomed Life Sci 2017 Nov 2;1068-1069:313-321. Epub 2017 Nov 2.

Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box: 14115-175, Tehran, Iran.

In this work, a microfluidic device was developed for on-chip electromembrane extraction of trace amounts of ephedrine (EPH) and clonidine (CLO) in human urine and plasma samples followed by HPLC-UV analysis. Two polymethylmethacrylate plates were used as substrates and a microchannel was carved in each plate. The microchannel channel on the underneath plate provided the flow pass of the sample solution and the one on the upper plate dedicated to a compartment for the stagnant acceptor phase. A piece of polypropylene sheet was impregnated by an organic solvent and mounted between the two parts of the chip device. An electrical field, across the porous sheet, was created by two embedded platinum electrodes placed in the bottom of the channels which were connected to a power supply. The analytes were converted to their ionized form, passed through the supported liquid membrane, and then extracted into the acceptor phase by the applied voltage. All the effective parameters including the type of the SLM, the SLM composition, pH of donor and acceptor phases, and the quantity of the applied voltage were evaluated and optimized. Several organic solvents were evaluated as the SLM to assess the effect of SLM composition. Other parameters were optimized by a central composite design. Under the optimal conditions of voltage of 74V, flow rate of 28μLmin, 100 and 20mM HCl as acceptor and donor phase composition, respectively, the calibration curves were plotted for both analytes. The limits of detection were less than 7.0 and 11μgL in urine and plasma, respectively. The linear dynamic ranges were within the range of 10-450 and 25-500μgL (r˃0.9969) for CLO, and within the range of 20-450 and 30-500μgL (r˃0.9907) for EPH in urine and plasma, respectively. To examine the capability of the method, real biological samples were analyzed. The results represented a high accuracy in the quantitative analysis of the analytes with relative recoveries within the range of 94.6-105.2% and acceptable repeatability with relative standard deviations lower than 5.1%.
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http://dx.doi.org/10.1016/j.jchromb.2017.10.062DOI Listing
November 2017

Magnetically assisted matrix solid phase dispersion for extraction of parabens from breast milks.

J Chromatogr A 2017 Jun 5;1504:17-26. Epub 2017 May 5.

Defense Chemical Research Laboratory (DCRL), Karaj, Iran.

In the present work, magnetically assisted matrix solid phase dispersion (MA-MSPD) was used as an efficient solid phase extraction method. MA-MSPD followed by a dispersive liquid-liquid microextraction (DLLME) was applied for determination of parabens in breast milks. The analysis were performed using LC-UV and LC-MS/MS. Poly(indole-thiophene) coated magnetic graphene oxide (MGO@PIT) was synthesized, characterized and used as the sorbent. NaSO was used as the drying salt as well as matrix dispersing agent. Exact amounts of MGO@PIT and NaSO were added into 200μL volume of the milk and the mixture was gently blended to obtain a dry powder. The blend was dispersed into ultrapure water and stirred. Because of dissolving of the matrix dispersant in water, only the magnetic sorbent is remained into water which can be easily separated by a magnet. Next, the sorbent was eluted with a suitable solvent to desorb the analyte and the eluent was used as the disperser solvent for the subsequent DLLME. In this approach, the target analytes were directly adsorbed on the surface of the magnetic sorbent without any sample pretreatment. Compared with conventional MSPD, MA-MSPD increases the simplicity of the extraction procedure, decreases the extraction time and eliminates the column packing as well as its related drawbacks. The optimum extraction parameters were obtained as 50mg of MGO@PIT, 550mg of NaSO in 200μL of the milk sample, 1.0mL of methanol as the eluent solvent under fierce vortex for 2.0min and 100μL of 1-octanol as the extraction solvent. Under the optimal conditions, the extraction recoveries greater than 83% were obtained, and LOD and LOQ values were found 25ngmL (about 0.5ngmL by LC-MS/MS) and 50ngmL using LC-UV, respectively. The calibration curves were in the range of 50-4000ngmL with the determination coefficients (R) higher than 0.998. Relative standard deviations (RSD%) for intra- and inter-day precisions were less than 7.5% and 11.3%, respectively. The results confirmed that the proposed method is a rapid, feasible and convenient technique which makes it suitable for the analysis of parabens from breast milk samples.
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http://dx.doi.org/10.1016/j.chroma.2017.05.009DOI Listing
June 2017

Determination of diclofenac using electromembrane extraction coupled with stripping FFT continuous cyclic voltammetry.

Anal Chim Acta 2017 Jun 10;972:38-45. Epub 2017 Apr 10.

Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran; Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.

For the first time, on-line and ultra-sensitive determination of trace amount of diclofenac in whole blood sample was performed by coupling of electromembrane extraction (EME) and stripping fast Fourier transform continuous cyclic voltammetry (SFFTCCV). In SFFTCCV, the potential waveform was continuously applied on a carbon paste electrode and the electrode response was obtained by subtracting the background current and integrating the current in potential range of the analyte oxidation. A central composite design was used for the optimization of the parameters influencing the extraction efficiency. By applying a DC potential of 20 V during 28 min of extraction, diclofenac was migrated from the sample solution (pH 5), into a thin layer of 1-octanol immobilized in the pores of a porous flat sheet membrane and then into the acceptor solution (pH 7). The method presented a good linearity within the range of 5-1000 ng mL with a determination coefficient of 0.993 in whole blood samples. Limits of detection (LOD) and quantification (LOQ) were found to be 1.0 ng mL and 5.0 ng mL respectively.
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http://dx.doi.org/10.1016/j.aca.2017.04.011DOI Listing
June 2017