ZIF67-derived porous carbon-reinforced electrospun nanofiber as an extractive phase for on-chip micro-solid-phase extraction of antifungals from biological fluids prior to liquid chromatography tandem mass spectrometry.

With a view to improving applicability as a sorbent while overcoming the challenges associated with its powdery nature, cobalt-doped zeolitic imidazolate framework (ZIF 67)-derived nanoporous carbon (Co-NPC) was employed as an additive in nanofiber through the process of electrospinning. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis were used to characterize the resulting nanocomposite. A microfluidic chip device with four layers, including two layers entailing spiral channels, was designed and employed to assess the analytical performance of the fabricated Co-NPC-reinforced electrospun composite. To do so, a folded piece of electrospun composite was sandwiched between two layers with spiral channels. Therefore, both sides of the folded composite acted as a sorptive phase to extract antifungal drugs as target analytes. The significant factors affecting the efficiency of the extraction process were investigated and optimized. Subsequently, the technique was verified through the utilization of liquid chromatography-tandem mass spectrometry (LC-MS/MS) by employing optimal parameters. The optimal conditions were applied to evaluate the figures of merit. A linear range was obtained for antifungal drugs within the range 0.25-200.0 ng ml-1 with an R2 value of ≥ 0.9914. The method demonstrated detection limits ranging between 0.08 and 0.40 ng ml-1. The intra-day and inter-day precisions were less than 6.9%. Relative recoveries exhibited variations between 91.4-106.8%, 95.9-103.6%, and 96.4-109.3% for ketoconazole, clotrimazole, and miconazole, respectively. The proposed approach yielded satisfactory results, demonstrating its efficiency.

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.

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

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-1 (R2 = 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-1 and 0.5 µg g-1, respectively. The intra-day and inter-day precisions (n = 3) at the concentrations of 2.0 and 10 ng mL-1 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%.

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.

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 (R2  = 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%.

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.

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-1 with R2 > 0.997. A limit of detection of 0.1 ng mL-1 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.

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.

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

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-1 for ATN and 0.3-500 ng mL-1 for CAP with r2 > 0.999. Limits of detection of 0.15 and 0.13 ng mL-1 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.

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

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-1 concentration range. The limits of detection for oxazepam and nitrazepam are 1.5 and 2.5 ng mL-1, respectively, and the relative standard deviations at the levels of 50, 100 and 250 ng mL-1 (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.

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

In this work, a novel sorbent based on polydopamine-functionalized magnetic ferric oxide (Fe3O4) 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-1, respectively. The calibration curve was linear over the concentration range of 3.0-300 ng mL-1 (R2 = 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-1) set by Codex Alimentarius Commission. The relative recoveries were obtained within the range of 86.5-93.6.

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

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-1 NSAID concentration range. Limits of detection and intra-day and inter-day RSDs are <10 ng.mL-1 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.

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

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 N2 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-1) and a wide linearity (0.5-200 µg.L-1) 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.

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

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-1 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-1 and 30-1000 µg L-1 ( r2 > 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.

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

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-1 HNO3 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-1 and 2.0 ng mL-1, respectively. An excellent linearity was achieved within the range of (10-800) ng mL-1 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.

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

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.

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.

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-1 for diazepam and 1.0 µg·L-1 for oxazepam. Repeatability and reproducibility for one fiber (n = 4), expressed as the relative standard deviation at a concentration of 50 µg·L-1, 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-1 diazepam concentration range, and from 1.0-1000 µg·L-1 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.

Polytetrafluoroethylene physisorption-assisted emulsification microextraction as a cleanup and preconcentration step in the gas chromatography determination of aliphatic hydrocarbons in marine sediment samples.

For the first time, the application of polytetrafluoroethylene powder as an extractant phase collector or holder in liquid-phase microextraction has been developed. For this purpose, the analytical performances of two different ways of applying polytetrafluoroethylene powder in microextraction methods including polytetrafluoroethylene physisorption-assisted emulsification microextraction and dispersive liquid-phase microextraction via polytetrafluoroethylene extractant phase holders have been compared for analysis of aliphatic hydrocarbons in aqueous phases. Under the same conditions, the former showed better extraction efficiencies over the latter and as a result, it was applied as preconcentration and cleanup step in the analysis of aliphatic hydrocarbons in sediment samples followed by gas chromatography analysis. The linearity of the polytetrafluoroethylene physisorption-assisted emulsification microextraction method was obtained over a range of 3.7 and 2000 ng/g (R2 > 0.993). The relative standard deviations were less than 6.5% (n = 3). The limits of detection and quantification obtained by this method were 1.1-9.0 and 3.7-30 ng/g, respectively, indicating that satisfactory results were achieved by the procedure.

A novel approach to the consecutive extraction of drugs with different properties via on chip electromembrane extraction.

In the present research, for the first time, a consecutive on chip electromembrane extraction coupled with high performance liquid chromatography was introduced for the analysis of betaxolol (Bet), naltrexone (Nalt) and nalmefene (Nalm) as model analytes with different chemical properties from biological samples. The chip consists of two polymethyl methacrylate (PMMA) parts where two microfluidic channels are carved in each part. These channels were used as a flow path for the sample solution and a thin compartment for the acceptor phase. A porous polypropylene sheet membrane impregnated with an organic solvent was placed between two parts of the chip device in order to separate the channels. Two platinum electrodes were bent at the bottom of these channels that are connected to a power supply providing the electrical driving force for migration of ionized analytes from the sample solution through the porous sheet membrane into the acceptor phase. The new setup provides effective and reproducible extractions by using a low volume of sample solution. Efficient parameters on consecutive electromembrane extraction of the model analytes were optimized by using the one variable at a time method. Under the optimized conditions, the new setup offered a good linearity in the range of 10.0-500 µg L(-1) with coefficient of determination (R(2)) higher than 0.9932. The relative standard deviation (RSD%) and LOD values were less than 6.8% based on four replicate measurements and 10.0 µg L(-1) for the model analytes, respectively. The preconcentration factors higher than 15.6-fold were obtained. Finally, the proposed method was successfully applied for determination and quantification of the model analytes in biological samples.

Low voltage electrically stimulated lab-on-a-chip device followed by red-green-blue analysis: a simple and efficient design for complicated matrices.

In the present work, a simple and portable analysis device was designed for the first time for the determination of lead ions as the model analyte. The basis of the lead analysis is its extraction and pre-concentration in an acceptor droplet via the application of an electrical field. The acceptor droplet is a KI solution and therefore, the formation of a yellow precipitation of PbI2 was a sign of the presence of lead ion in the solution. Following this, digital picture of the final acceptor droplet was analyzed by investigating its Red-Green-Blue (RGB) components. The results show that the RGB intensities of the acceptor phase are proportionate to the lead concentration in the sample solution. Also, a 9.0 V battery was used to apply the electrical field, and other effective parameters, such as the type of organic liquid membrane, pH of the sample solution, and the extraction time, were considered to obtain the optimal conditions. The model analyte was determined by extracting it from a 100 µL sample solution across a thin layer of 1-octanol, immobilized in the pores of a polypropylene membrane sheet, and into the acceptor droplet via applying a 9.0 V electrical potential for 20 min. The device is capable of determining lead ions down to 20.0 ng mL(-1), with admissible repeatability and reproducibility (the intra- and inter-assay precision ranged between 3.8-7.0% and 9.8-11.9%, respectively). Also, we calculated error% for the model analyte in the range of -8.5 to +4.5, which suggests that the chip offers acceptable accuracy for the analysis of lead ions. The linearity was studied in the range of 50.0-1500 ng mL(-1), with a correlation coefficient of 0.9994. Finally, the designed device was used for the analysis of lead in real samples.