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In this work a novel nanocomposite coating with high thermal stability and high durability is prepared. The surface of the stainless steel as a support was initially modified by (3–mercaptopropyl)trimethoxysilane. Surface characteristics of pure titania (TiO2), pure hydroxyapatite (HAP) and Hap/TiO2 nanocomposite coating were investigated and compared by energy dispersive X–ray (EDX) spectroscopy as well as by field emission–scanning electron microscopy (FESEM). The mutual effects of components on each other were discussed. Addition of HAP sol to the pure TiO2 sol, considerably changes the coating morphology. The applicability of the sol–gel HAP/TiO2 fiber was assessed for the headspace solid–phase microextraction (HS–SPME) of benzene, toluene, ethylbenzene and xylenes (BTEXs) from water sample followed by gas chromatography–mass spectrometry (GC–MS). Important parameters affecting the extraction efficiency were investigated. The efficiency of HAP/TiO2 nanocomposite coating was compared with other reported fibers and showed very good results. Under optimal conditions, the detection limits (S/N = 3) were in the range of 0.04 to 1 μg L−1, and the limits of quantification (S/N = 10) were between 0.1 and 4 μg L−1. The relative standard deviations (RSDs) for each fiber (at 20 μg L−1 and n = 5) were in the range of 1.76 to 8.18%, while the RSDs between fibers were 3.03 to 10.02%. The method showed a large linearity in the range from 0.1 to 1000 μg L−1 with correlation coefficients of >0.995.

In this study, preparation of a solid-phase microextraction fiber of polydimethylsiloxane (PDMS) polymer in its blends with polystyrene (PS) via electrospinning process, on a stainless steel wire has been reported. The electrospining enhancement of PDMS solutions in the presence of PS is found due to the increase in the viscosity of the mixed solutions. Characteristics of the fibers were inspected by energy dispersive X-ray spectroscopy, scanning electron microscopy and field emission scanning electron microscopy. The applicability of the coating was assessed for headspace solid phase microextraction (SPME) of some residual solvents (Diethyl Ether, Toluene and Chloroform) from biological products (Anti venin and Foot-and-mouth disease vaccine) followed by gas chromatography–mass spectrometry. The effects of extraction time and temperature, desorption time and temperature, agitation rate and ionic strength on the extraction efficiency were investigated. Under optimized conditions, limits of detection in the range of 2–10 µgL-1 and limits of quantification in the range of 10–50 µgL-1 were obtained. The method showed linearity in a wide range with a correlation coefficient greater than 0.99. In addition, the obtained inter-day and intra-day precisions were in the range of 1.57 to 8.28% and 4.87 to 11.72%, respectively. The thermal stability of the fiber was also investigated and it was found to be durable at 230°C for 450 min. Furthermore, the proposed method was successfully applied for quantification of chloroform in Foot-and-mouth disease vaccine and diethyl ether and toluene in Anti-venin with recoveries in the range of 78.84- 123.01%.

Innovations in extraction phases, extraction modes and hyphenated instrument configurations, are the most important issues to address for progress in the solid phase microextraction (SPME) methodology. In this regard, we have embarked on the development of a novel biocompatible 96-monolithic inorganic hollow fiber (96-MIHF) array as a new configuration for high-throughput SPME on a 96-well plate system. An arrangement of highly ordered 96 titania/Hydroxyapatite (TiO2/HAP) nanocomposite hollow fibers and corresponding stainless-steel needles on a Teflon plate holder were used as the extraction module. The inorganic hollow fibers were prepared via a rapid and reproducible template approach (Polypropylene hollow fiber) in combination with a sol-gel method in the presence of polyvinyl alcohol (PVA), as a network maker. The hollow fiber-shape sorbents were obtained with excellent precision by weight (RSD% = 4.98, n = 10) and length (RSD% = 1.08, n = 10) criteria. The proposed design can overcome a number of geometrically dependent drawbacks of conventional high-throughput SPME methods, mainly the ones related to sorbent amount and surface area due to possessing inner/outer surfaces without additional internal supports. The SPME platform, for the first time, was successfully applied for the extraction and preconcentration of doxorubicin from urine and water media without requiring sample preparation and free from significant matrix effect. The extracted analyte was analyzed by liquid chromatography-ion trap tandem mass spectrometry (LC-MS/MS). Highly satisfactory analytical figures of merit were obtained under optimized conditions. The limit of detection (LOD), limit of quantification (LOQ) and linearity of determination were 0.1 ng mL−1, 0.25 ng mL−1 and 0.25 to 4000 ng mL−1, respectively. The interday, intraday and inter sorbent precisions for three concentration levels ranged from 2.01 to 8.09 % (n = 3), 1.02 to 8.65 % (n = 5) and 0.99 to 1.02% (n = 15), respectively. The mean intra-well RSD value for 96 individual wells in 96-MIHF-SPME-LC-MS/MS (n = 3) at the medium concentration level was 7.81%.

A fast, selective and sensitive reversed-phased liquid chromatography coupled to ion-trap mass spectrometry has been developed to elucidate and confirm the diazinon metabolites with a wide range of...

Vaccine production is a biological process in which variation in time and output is inevitable. Thus, the application of Process Analytical Technologies (PAT) will be important in this regard. Headspace solid - phase microextraction (HS-SPME) coupled with GC–MS can be used as a PAT for process monitoring. This method is suitable to chemical profiling of volatile organic compounds (VOCs) emitted from microorganisms. Tetanus is a lethal disease caused by Clostridium tetani (C. tetani) bacterium and vaccination is an ultimate way to prevent this disease. In this paper, SPME fiber was used for the investigation of VOCs emerging from C. tetani during cultivation. Different types of VOCs such as sulfur-containing compounds were identified and some of them were selected as biomarkers for bioreactor monitoring during vaccine production. In the second step, the portable dynamic air sampling (PDAS) device was used as an interface for sampling VOCs by SPME fibers. The sampling procedure was optimized by face-centered central composite design (FC-CCD). The optimized sampling time and inlet gas flow rates were 10 min and 2 m L s−1, respectively. PDAS was mounted in exhausted gas line of bioreactor and 42 samples of VOCs were prepared by SPME fibers in 7 days during incubation. Simultaneously, pH and optical density (OD) were evaluated to cultivation process which showed good correlations with the identified VOCs (>80%). This method could be used for VOCs sampling from off-gas of a bioreactor to monitoring of the cultivation process.

Magnetic graphene oxide nanocomposite has been proposed as a promising and sustainable sorbent for the extraction and separation of target analytes from food matrices. Sample preparation based on nanocomposite presents several advantages, such as desired efficiency, reasonable selectivity and high surface-area-to-volume ratio.; Results: A new graphene oxide/Fe3 O4 @polythionine (GO/Fe3 O4 @PTh) nanocomposite sorbent was introduced for magnetic dispersive solid-phase extraction and flame atomic absorption spectrometric detection of zinc(II) in water, flour, celery and egg. To fabricate the sorbent, an oxidative polymerization of thionine on the surface of magnetic GO was applied, while polythionine was simply employed as a surface modifier to improve extraction yield. The properties of the sorbent were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis, vibrating sample magnetometry and Fourier transform-infrared spectroscopy. The calibration curve showed linearity in the range of 0.5-30 ng mL-1 . Limits of detection (S/N = 3) and quantification (S/N = 10) were 0.08 and 0.5 ng mL-1 , respectively.; Conclusion: The method was applied for trace-level determination of Zn(II) in water and food samples, and its validation was investigated by recovery experiments and analyzing certified reference material. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

A novel and efficient headspace solid-phase microextraction (HS-SPME) method, followed by gas chromatography mass spectrometry (GC-MS), was developed to study volatile organic compounds (VOCs) emerging from microorganisms. Two homemade SPME fibers, a semi-polar poly (dimethylsiloxane) (PDMS) fiber, and a polar polyethylene glycol (PEG) fiber, along with two commercial fibers (PDMS and PDMS/DVB) were used to collect VOCs emerging from Clostridium tetani which was cultured in different media. The adsorbed VOCs were desorbed and identified, in vitro, using GC-MS. The adsorption efficiency was improved by optimizing the time duration of adsorption and desorption. About 50 components were identified by the proposed method. The main detected compounds appeared to be sulfur containing compounds such as butanethioic acid S-methyl ester, dimethyl trisulfide, and dimethyl tetrasulfide. These volatile sulfur containing compounds are derived from amino acids containing the sulfur element, which probably coexist in the mentioned bacterium or are added to the culture media. The developed HS-SPME-GC-MS method allowed the determination of the chemical fingerprint of Clostridium tetani volatile constituents, and thus provides a new, simple, and reliable tool for studying the growth of microorganisms. Graphical abstract Investigation of biogenic VOCs released from Clostridium tetani using SPME-GC-MS.

An imprinted interpenetrating polymer network (IPN) was synthesized and used as a medium for isolation of carbamazepine from urine samples. The polymer network consisted of a homogeneous polystyrene–sol gel hybrid constructed by in–situ radical polymerization method. In this process, within the sol–gel reaction duration, styrene monomer could penetrate into the reaction mixture and after the polymerization initiation, a monolithic IPN structure was prepared. The scanning electron microscopy (SEM) image and energy dispersive spectroscopy (EDX) are indications of the polystyrene dispersion at nano- to micro-meter level in the sol gel matrix. Eventually, the synthesized IPN was used as a sorbent in microextraction in packed syringe (MEPS) combined with high performance liquid chromatography (HPLC) for isolation of carbamazepine, naproxen and dexamethasone from urine samples. The molecularly imprinted IPN showed some degree of selectivity towards carbamazepine. To assess the important parameters influencing the extraction and desorption processes, an experimental design strategy was used. By the current method, low limits of detection (1.3–1.5 μg L −1 ) and quantification (4.2–5 μg L −1 ) were achieved (hydrocortisone as the internal standard). The intra- and inter-day precision data at 50 and 300 μg L −1 were 1.3–7.4%, while the working linear dynamic range was from 4.2 to 500 μg L −1 .

A novel, simple and convenient method based on dispersive liquid–liquid microextraction (DLLME) and derivatization was developed and applied for isolation of a couple of selected chlorophenoxy acid herbicides from aquatic media. In the first step, analytes were extracted from acidic media into carbon tetrachloride phase using a DLLME. In following, derivatization was carried out on extracted compounds by means of methylation with an acidic methanol solution to increase their volatility and detectability in gas chromatography analysis. Finally, the derivatized analytes were re-extracted in the carbon tetrachloride phase in the second DLLME. Some important extraction parameters such as the nature and volume of the extraction solvent, disperser solvent, pH and the ionic strength were optimized. Subsequently, the developed method was validated by gas chromatography–mass spectrometry (GC–MS). Under the optimum conditions, the linearity was studied at the concentration range of 1–100 µg L−1 with a satisfactory coefficient of determination (r 2 > 0.99) for all the studied analytes. Also, the relative standard deviations (RSD %) values were from 2.5 to 4.5 % at the concentration levels of 2 and 50 µg L−1. The detection limits were found to be in the range of 0.15–0.31 µg L−1 using time-scheduled selected ion monitoring (SIM) mode. The developed method was successfully applied to the extraction and determination of chlorophenoxy acid herbicides in the river and tap water samples.

A high-throughput micro-solid-phase extraction device based on a 96-well plate was constructed and applied to the determination of pesticide residues in various apple samples. Butyl methacrylate and ethylene glycol dimethacrylate were copolymerized as a monolithic polymer and placed in the cylindrically shaped stainless-steel meshes of 96-micro-solid-phase extraction device and used as an extracting unit. Before the micro-solid-phase extraction, microwave-assisted extraction was employed to facilitate the transfer of the pesticide residues from the apple matrix to liquid media. Then, 1 mL of the aquatic samples was transferred into the 96-well plate and the 96-micro-solid-phase extraction device was applied for the extraction of the selected pesticides. Influential parameters, such as sorbent-to-sorbent reproducibility, microwave-assisted extraction time, ionic strength and micro-solid-phase extraction time, were optimized. The limits of quantitation were below 120 μg/kg, which are lower than the maximum residue limits. The developed method was successfully implemented for the extraction and determination of the selected pesticides from 20 different apple samples gathered from local markets. Phosalone was identified and quantified at the concentration level of 147 (±16.4) μg/kg in one of the samples.

A cryogel–based semi–interpenetrating polymer network (Cryo–SIPN) was prepared in which conductive polymers such as polyaniline (PANI) and polypyrrole (PPy) were formed within the super porous network of acrylic acid cryogel. For completion of cryo-polymerization, all the constituent solutions were severely mixed and placed into the plastic straws and kept at -20°C and then the synthesized cyrogels were cut into the 1-cm length and freeze dried after washing with water. The Cryo–SIPN polymeric composite was applied in micro solid phase extraction (µSPE) of some selected antibiotic residues from various samples. The µSPE method combined with a high performance liquid chromatography–ultraviolet (HPLC–UV) system allowed trace quantification of antibiotic residues in the honey and water samples while the significant variables were optimized using a central composite design (CCD) to find optimum conditions. The method performance was satisfactory with recovery ranges from 70.0 to 109%. The limits of detection (S/N = 3) and quantification (S/N = 10) for all samples were within the 17–50 μg kg−1 and 47–140 μg kg−1 range, respectively. The relative standard deviation was less than 10 % for antibiotics in the foodstuff and water samples. The validated Cryo–SIPN–µSPE in conjunction with HPLC–UV, proved to be versatile, efficient and robust while its capability toward the trace determination of drugs residues in real-life samples is demonstrated in this work.

A simple magnetic dispersive solid-phase extraction (MDSPE) methodology based on mesoporous Fe3O4@ succinic acid nanospheres and high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS) has been developed to determine kanamycin (KNM) and neomycin (NEO) contents in Measles, Mumps, and Rubella (MMR) vaccine products. The monodispersed mesoporous Fe3O4 nanospheres with self-assembled carboxyl terminated shell have been prepared via a simple solvothermal method. These as-synthesized mesoporous Fe3O4 nanospheres showed a high magnetic saturation value (Ms = 46 emu g−1) and large specific surface area (111.12 m2 g−1) which made them potential candidates as sorbents in magnetic solid-phase extraction. The adsorption experimental data fitted well with the Freundlich-Langmuir isotherm and followed a pseudo-second-order kinetic model. Moreover influential parameters on extraction efficiency were investigated and optimized. Under optimal conditions, the limits of detection for KNM and NEO were 1.0 and 0.1 ng mL−1, respectively. Recovery assessments using real samples exhibited recoveries in the range of 96.0 ± 4.3 to 101.5 ± 7.1 %, with relative standard deviations of

Concerns for the use of non-purified or incompletely purified inactivated foot-and-mouth disease (FMD) vaccine, like difficulties for differentiation vaccinated from infected animals, can be a motivation in order to develop methods based on size exclusion chromatography (SEC). In this study, a two dimensional size exclusion chromatography (2D-SEC) system was successfully constructed using two different SEC column media to achieve a high-throughput purification system for the cell culture-derived foot and mouth diseases virus (FMDV). A mathematical model was also utilized to predict and to get a better insight into the separation process. Column and the packing particles characteristics such as column void volume, total column volume, particle porosity and accessible particle porosity was acquired experimentally. Retention times and elution profile of two different molecules, blue dextran and bovine serum albumin, were used for evaluating the capability of SEC media for separating two critical impurities (residual DNA (rDNA) and non-structural protein (NSP)) from active ingredient of vaccine (FMDV particle). Experiments were carried out with two different commercial columns (XK 26/60) and (XK 16/100) and with four different packing media superdex 200 prep grade, sephacryl S-500 HR, Sephacryl S-400 HR and Sephacryl S-300HR. The mathematical model was first validated by experimental chromatographic data of different SEC media and was then used to propose the best 2D-SEC system for downstream processing of the FMDV vaccine. The loading capacity of the constructed 2D-SEC sample was increased to 12.5% of total column volume and the purity of the final product was more than 90%. The entire purification process was performed with 77% FMDV recovery and 79.1% virus yield. Based on the high-performance size exclusion chromatography (HPSEC), the purity of the final NSP-free FMDV was about 90% and over 94.6% of host cell DNA was removed. Analyses of the purified FMDV by HPSEC, transmission electron microscopy (TEM) and dynamic light scattering (DLS) indicated that the final product had spherical shape with mean size about 30 nm and their structure remained intact.

For the first time, electrospun polystyrene nanostructure was used as coating material on a stainless steel wire for solid-phase microextraction. Surface morphology of the coating was studied by scanning electron microscopy which showed the formation of nanofibers on the wire. The coating was stable after conditioning at 250°C for 2h. The efficiency of the polystyrene coating was approved by extracting a mixture of seven pesticides (polar and apolar) from head space of honey samples followed by gas chromatography-mass spectrometry. The important parameters affecting extraction efficiency such as, extraction time and temperature, desorption conditions, agitation rate and ionic strength were investigated. Under optimized experimental conditions, detection limits for the investigated pesticides ranged from 0.1-2μgL(-1). The intra- and inter-day precisions of the developed method were 3.5-17.6% and 10.0-25.0%, respectively. Finally, all the investigated pesticides were spiked to honey samples and extracted by the proposed method. The accuracies of determination of all the species were found to be in the range of 81-125%.

In this study, organic aerogels were synthesized by the sol-gel polycondensation of mixed cresol with formaldehyde in a slightly basic aqueous solution. Carbon aerogels and xerogels are generated by pyrolysis of organic aerogels. The novel sol-gel-based micro-solid-phase extraction sorbent, resorcinol-formaldehyde xerogel, was employed for preconcentration of some selected herbicides. Three herbicides of the aryloxyphenoxypropionate group, clodinafop-propargyl, haloxyfop-etotyl, and fenoxaprop-P-ethyl, were extracted from aqueous samples by micro-solid-phase extraction and subsequently determined by gas chromatography with mass spectrometry. The effect of different parameters influencing the extraction efficiency of these herbicides including sample flow rate, sample volume, and extraction time were investigated and optimized. Under optimum conditions, linear calibration curves in the range of 0.10-500 ng/L with R(2) > 0.99 were obtained. The relative standard deviation at 50 μg/L concentration level was lower than 10% (n = 5) and detection limits were between 0.05 and 0.20 μg/L. The proposed method was successfully applied to the sampling and extraction of herbicides from Zayanderood and paddy water samples.

An attempt was made to combine μ-solid phase extraction and headspace single drop microextraction techniques and use their advantages for trace determination of some volatile organic compounds in aqueous samples. After performing the two-step preconcentration approach, the desired analytes were determined by gas chromatography-mass spectrometry. A resorcinol-formaldehyde-based xerogel was used as the extraction medium in the μ-solid phase extraction (μ-SPE) method. Then, the extracted BTEX was eluted with a rather large amount of methanol. To remove the laborious process including solvent evaporation and further reconstitution, which is usually accompanied by loss of analytes and accuracy, headspace single drop microextraction (HS-SDME) was employed as the second orthogonal enrichment technique. The combination of these two techniques led to enrichment factors ranging from 118 to 504 for the extracted BTEX indicating the enhanced capability of the method towards aromatic compounds. Under optimum conditions, the limit of detection (LOD) varied from 0.03 to 0.1 μg L−1 and the linearity for the analytes was in the range of 0.1–100 μg L−1, while the RSD% values (n = 5) were all satisfactory at two concentration levels of 0.1 and 100 μg L−1. The applicability of the developed μ-SPE/HSSDME/GC-MS method was examined by analyzing river and paddy water samples and acceptable relative recovery percentages were obtained.

Sol-gel based solid-phase microextraction fibers supported by a stainless steel wire were fabricated and employed for GC-MS determination of oxadiargyl in real samples. The fibers were based on four compounds with different polarity: polar and non-polar (end-capped) poly(dimethylsiloxane) (PDMS), polyethylene glycol (PEG), and poly(ethylene-propyleneglycol)-monobutyl ether (UCON). For this purpose, the surface of the stainless steel was initially modified by (3-mercaptopropyl) trimethoxysilane. The results of the modification procedure were evaluated by cyclic voltammetry and energy dispersive X-ray (EDX) spectroscopy. After the modification, four different sol-gel based SPME fibers with different values of polarity, polar and non-polar PDMS, PEG, and UCON have been prepared and investigated. They are supposed to be employed to determinate oxadiargyl in agricultural and environmental samples prior to gas chromatography-mass spectrometry analysis. Most important parameters that affect the extraction efficiency were also optimized. Under optimized conditions, the proposed method was found to be linear for the concentrations ranging from 100 ng L(-1) to 2 mg L(-1) with R(2)=0.997. Limit of detection (LOD) of 40 ng L(-1) and relative standard deviation of less than 10% were obtained. Relative recovery in environmental and agricultural samples was in the range of 73-96%.

A headspace solid-phase microextraction method coupled to GC-MS was successfully developed for the trace determination of formaldehyde in veterinary bacterial and human vaccines, and diphtheria-tetanus antigen. The formaldehyde was derivatized by means of the Hantzsch reaction prior to extraction and subsequent determination. Three different types of solid-phase microextraction fibers, polar, and nonpolar poly(dimethylsiloxane) and polyethylene glycol were prepared by using a sol-gel technique. The effects of different parameters such as type of fiber coating, extraction time and temperature, desorption conditions, agitation rate, and salt effect were investigated. Under the optimized conditions, the detection limit of the method was 979 ng/L using the selected ion-monitoring mode. The interday and intraday precisions of the developed method under the optimized conditions were below 13%, and the method shows linearity in the range of 1.75-800 μg/L with a correlation coefficient of 0.9963. The optimized method was applied to the determination of formaldehyde from some biological products. The results were satisfactory compared to the standard method.

A novel high-throughput device based on 96-micro-solid phase extraction (96-μ-SPE) system was constructed for multiresidue determination of nine pesticides in aquatic samples. The extraction procedure was performed on a commercially available 96-well plate system. The extraction module consisted of 96 pieces of 1 cm × 3 cm of cylindrically shaped stainless steel meshes. The prepared meshes were fixed in a home-made polytetrafluoroethylene-based constructed ninety-six holes block for possible simultaneous immersion of meshes into the center of individual wells. Dodecyl methacrylate and ethylene glycol dimethacrylate was copolymerized as a monolithic polymer and placed in the cylindrically shaped stainless steel meshes as extracting medium. A volume of 1 mL of the aquatic sample was transferred into the 96-well plate and the 96-μ-SPE device was applied for the extraction of the selected pesticides. Subsequently, the extracted analytes were analyzed by gas chromatography–mass spectrometry. Influential parameters such as polymer synthesis conditions, sorbent-to-sorbent reproducibility, ionic strength and extraction time were optimized. Intra and inter-sorbent reproducibility on 96-μ-SPE device were evaluated and results revealed that extraction yields are rather similar. Limits of detection were below 4 μg L−1 and the coefficient of determination was satisfactory (r2 > 0.99) for all the studied analytes. The developed method was successfully applied to the extraction and determination of the selected pesticides in surface water samples.

An immersed solvent microextraction (SME) method was successfully developed for the trace enrichment of aryloxyphenoxypropionate herbicides from aquatic media. A microdrop of toluene was used as the extraction solvent. Some important extraction parameters such as type of solvent, solvent dropsize, stirring rate, ionic strength and extraction time were investigated and optimized. The microdrop volume of 1.5 µL, a sampling time of 25 min, and use of toluene were major parameters for achieving high enrichment factors. The linearity was studied by preconcentration of 4 mL of the water samples spiked with a standard solution of aryloxyphenoxypropionates at the concentration range of 0.15 to 30 ng mL−1. The coefficient of determination was satisfactory (r 2 > 0.99) for all the studied analyte and the relative standard deviations (RSD%) values under the optimized condition were found to be 1.7 to 14.2% at the concentrations of 1 and 10 ng mL−1. The enrichment factors were from 217 to 403 for the samples spiked a...

Electrospinning technique was used to convert polydimethyl siloxane (PDMS) sol-gel solution to a new nanostructure on a stainless steel wire. The surface morphology of the fiber was observed by scanning electron microscopy (SEM). It showed a diameter range of 30-60nm for PDMS nanoparticles with a homogeneous and porous surface structure. The applicability of this coating was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples followed by gas chromatography-mass spectrometry. The important parameters affecting extraction efficiency such as extraction time and temperature, desorption conditions, agitation rate and ionic strength were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.3-5μgL(-1) and 1-10μgL(-1) were obtained, respectively. The method showed linearity in the broad range of 1-5000μgL(-1) with correlation coefficient of >0.99. Inter-day and intra-day precisions of the developed method ranged from 2.43% to 6.54% and from 5.24% to 13.73%, respectively. The thermal stability of the fiber was investigated on stainless steel wire. It was found to be durable at 260°C for more than 360min. Furthermore, the proposed method was successfully applied for quantification of BTEX in real water samples.

A polypropylene (PP) sheet was successfully applied as an extracting medium for trace enrichment of fluoxetine (FLX) from urine samples, followed by high performance liquid chromatography-fluorescence detection (HPLC-FD). The extraction medium was a square, 1 × 1 cm2 piece of polypropylene membrane sheet that was conditioned in methanol. The extraction process was conveniently carried out using a 5 mL urine sample. After extraction, the PP sheet was withdrawn and transferred to a glass vial for performing the desorption process using 210 µL organic solvent. After complete drying, the residue was dissolved in 50 µL of methanol and an aliquot of 20 µL was, finally, injected into the HPLC system. Some important extraction parameters such as desorption solvent, pH, ionic strength, desorption, and extraction time were investigated and optimized. The linearity was studied by preconcentration of 5 mL of urine sample spiked with a standard solution of fluoxetine at the concentration range of 10–100 µg L−1. The co...

A high-throughput solid-phase microextraction (SPME) on 96-well plate together with gas chromatography–mass spectrometry (GC–MS) was developed for the determination of some selected pesticides in cucumber samples. Pieces with the length of 1.0 cm of silicon tubing were precisely prepared and then coated on the end part of stainless steel wires. The prepared fibers were positioned in a home-made polytetrafluoroethylene (PTFE)-based constructed ninety-six holes block to have the possibility of simultaneous immersion of the SPME fibers into the center of individual wells. Pesticides such as diazinon, penconazol, tebuconazol, bitertanol, malathion, phosalone and chlorpyrifos-methyl were selected for their highly application in cucumber field. The performances of the SPME fibers, such as intra and inter-fibers reproducibility, were evaluated and the results showed a good similarity in extraction yields. A volume of 1 mL of the aquatic supernatant of the cucumber samples was transferred into the 96-well plate and the array of SPME fibers was applied for the extraction of the selected pesticides. The important parameters influencing the whole extraction process including, organic solvent percent, salt addition, dilution factor, stirring rate and extraction time were optimized. The inter- and intra-day RSD% were found to be less than 15.4%. Limits of detection (LOD) and limits of quantification (LOQ) were below 60 and 180 μg kg −1 , respectively. The coefficient of determination was satisfactory ( r 2 > 0.99) for all the studied analytes. The developed method was successfully applied to the monitoring of several samples gathered from local markets.

Chemical modification or mutation of proteins may bring about significant changes in the net charge or surface hydrophobicity of a protein structure. Such events may be of major physiological significance and may provide important insights into the genetics of amyloid diseases. In the present study, fibrillation potential of native and chemically-modified forms of bovine carbonic anhydrase II (BCA II) were investigated. Initially, various denaturing conditions including low pH and high temperatures were tested to induce fibrillation. At a low pH of around 2.4, where the protein is totally dissociated, the apo form was found to take up a pre-molten globular (PMG) conformation with the capacity for fibril formation. Upon increasing the pH to around 3.6, a molten globular (MG) form became abundant, forming amorphous aggregates. Charge neutralization and enhancement of hydrophobicity by methylation, acetylation and propionylation of lysine residues appeared very effective in promoting fibrillation of both the apo and holo forms under native conditions, the rates and extents of which were directly proportional to surface hydrophobicity, and influenced by salt concentration and temperature. These modified structures underwent more pronounced fibrillation under native conditions, than the PMG intermediate form, observed under denaturing conditions. The nature of the fibrillation products obtained from intermediate and modified structures were characterized and compared and their possible cytotoxicity determined. Results are discussed in terms of the importance of surface net charge and hydrophobicity in controlling protein aggregation. A discussion on the physiological significance of the observations is also presented.

In this work a novel unbreakable sol–gel-based in-tube device for on-line solid phase microextraction (SPME) was developed. The inner surface of a copper tube, intended to be used as a high performance liquid chromatography (HPLC) loop, was electrodeposited by metallic Cu followed by the self assembled monolayers (SAM) of 3-(mercaptopropyl) trimethoxysilane (3MPTMOS). Then, poly (ethyleneglycol) (PEG) was chemically bonded to the –OH sites of the SAM already covering the inner surface of the copper loop using sol–gel technology. The homogeneity and the porous surface structure of the SAM and sol–gel coatings were examined using the scanning electron microscopy (SEM) and adsorption/desorption porosimetry (BET). The prepared loop was used for online in-tube SPME (capillary microextraction) of some selected polycyclic aromatic hydrocarbons (PAHs), as model compounds, from the aquatic media. After extraction, the HPLC mobile phase was used for on-line desorption and elution of the extracted analytes from the loop to the HPLC column. Major parameters affecting the extraction efficiency including the sample flow rate through the copper tube, loading time, desorption time and sample volume were optimized. For investigating the sorbent efficiency, four loops based on the copper tube itself, the copper tube after electrodeposition with Cu and the tubes with the SAMs and SAMs-sol–gel coating were made and compared. The SAMs-sol–gel coated loop clearly shows a prominently lead of at least 20–100 times of higher efficiency. The linearity for the analytes was in the range of 0.01–500 μg L −1 . Limit of detection (LOD) was in the range of 0.005–0.5 μg L −1 and the RSD% values ( n = 5) were all below 8.3% at the 5 μg L −1 level. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples were from 90 to 104%. The prepared loop exhibited long life time due to its remarkable solvent and mechanical stability. Different solvents such as methanol, acetonitrile and acetone were passed through the loop for many days and it was also used for more than 100 extractions/desorption of the selected analytes and no decrease in the peak areas was observed.

In this study, directly suspended liquid-phase microextraction was investigated for the extraction and determination of five chlorophenoxy acid herbicides in water samples. The optimized parameters for extraction of chlorophenoxy acid herbicides were 1 M HCl concentration in sample solution, solution temperature 20 °C, 45-min extraction time, 1,000 rpm stirring rate, 25 μL extracting solvent volume and without NaCl addition. Under the optimum conditions, the enrichment factor ranged from 192 to 390. Calibration curves yielded good linearity (R 2 > 0.999) and the linear range was 5.0–500.0 μg L−1, limit of detection was 0.3–0.4 μg L−1 and limit of quantification was 1–2 μg L−1 for analytes and the relative standard deviations were in the range of 3–10% (n = 3). Finally, the proposed method was successfully applied to the quantification of five chlorophenoxy acid herbicides in water samples and recovery was in the range of 74–110%.

Solid-phase microextraction (SPME) has been demonstrated to be useful for in vivo sampling in pharmacokinetic studies. In this study, a single time-point kinetic calibration for in vivo dynamic monitoring was developed by simplification of the laborious multiple time-point kinetic calibration, based on the independent desorption kinetics of the preloaded standards from SPME fibers with the changing analyte concentrations. The theoretical foundation and practical application conditions, such as the replicate numbers, the optimal time-point for desorption, and the sampling time, were systematically investigated. Furthermore, the feasibility of using regular standards rather than deuterated ones for the kinetic calibration was justified by comparing to the data obtained using the deuterated standards. All the methods were verified by in vitro and in vivo experiments. The results from in vivo SPME were validated by the blood drawing and chemical assay. These simplified calibration methods improved the quantitative applications of SPME for dynamic monitoring and in vivo sampling, enhance the multiplexing capability and automatic potentials for high throughput analysis, and decrease expenses on reagents and instruments.

A headspace solid-phase microextraction (HS-SPME) method was developed for the trace determination of geosmin in water and apple juice samples. A poly(dimethylsiloxane) (PDMS) fiber was synthesized as coated fiber using sol-gel methodology. After performing the extraction in the headspace, the fiber was introduced directly into the injection port of a gas chromatography-mass spectrometry (GC–MS) using electron impact (EI) ionization mode. One-at-the-time optimization strategy was applied to investigate and optimize important extraction parameters such as extraction temperature and time, ionic strength, headspace volume, and desorption temperature and time. The analytical data exhibited an RSD of 2–15%, a linear calibration range of 1–1,000 ng L−1, and a detection limit of 0.30 ng L−1 using selected ion monitoring (SIM) mode. The proposed method was successfully applied to the extraction and determination of geosmin in the spiked real water and apple juice samples and a relative recovery of 95–102% were achieved. The developed method offers the advantage of being simple to use, with shorter analysis times, lower cost of equipment, very little matrix effect, and high relative recovery in comparison to conventional methods of analysis.

A fiber coating from polyaniline (PANI) was electrochemically prepared and employed for solid phase microextraction (SPME) of some polycyclic aromatic hydrocarbons (PAHs) from water samples. The PANI film was directly electrodeposited on the platinum wire surface in sulfuric acid solution using cyclic voltammetry (CV) technique. The applicability of this coating was assessed employing a laboratory-made SPME device and gas chromatography with mass spectrometry (GC-MS) for the extraction of some PAHs from the headspace of aqueous samples. Application of wider potential range in CV led to a PANI with more stability against the temperature. The homogeneity and the porous surface structure of the film were examined by the scanning electron microscopy (SEM). The study revealed that this polymer is a suitable SPME fiber coating for extracting the selected PAHs. Important parameters influencing the extraction process were optimized and an extraction time of 40 min at 40 degrees C gave maximum peak area, when the aqueous sample was added with NaCl (20%, w/v). The synthesis of the PANI can be carried out conveniently and in a reproducible manner while it is rather inexpensive and stable against most of organic solvents. The film thickness of PANI can be precisely controlled by the number of CV cycles. The resulting thickness was roughly 20 microm after 20 cycles. At the optimum conditions, the relative standard deviation (RSD) for a double distilled water spiked with selected PAHs at ppb level were 8.80-16.8% (n = 3) and detection limits for the studied compounds were between 0.1-6 pg mL(-1). The performance of PANI was, also, compared with a commercial solid coated-based SPME fiber, carbowax/divinylbenzene (CW/DVB), under similar experimental conditions.

The on-fiber standardization technique for solid-coated solid-phase microextraction (SPME) was studied, and a theoretical model is proposed for the isotropic behavior of adsorption and desorption, based on Fick's law of diffusion and the Langmuir model. The isotropy of the adsorption and desorption of analytes onto and from the surface of porous solid SPME fiber was validated with the use of a commercially available fiber, a 50-μm Carbowax/templated resin for carbamate pesticide analysis in various sample matrixes, and a self-made polypyrrole fiber for diazepam analysis in blood samples. Time constants were comparable for the adsorption and desorption processes. Equilibrium constants and fiber capacities were calculated with the Langmuir isotherm model. A kinetic method was developed to calibrate adsorption using desorption. This calibration corrected for the sample matrix effects and minimized displacement effects as a pre-equilibrium extraction. The technique was successfully applied to the analysis of ...

A novel solid-phase microextraction(SPME) fiber was prepared using sol-gel technology with ethoxylated nonylphenol as a fiber coating material. The fiber was employed to develop a headspace SPME-GC-MS method suitable for quantification of 13 polycyclic aromatic hydrocarbons (PAHs) in water samples. Surface characteristics of the fibers were inspected by energy dispersive X-ray (EDX) spectroscopy as well as by scanning electron microscopy (SEM). The SEM measurements showed the presence of highly porous nano-sized particles in the coating. Important parameters affecting the extraction efficiency such as extraction temperature and time, desorption conditions as well as ionic strength have been evaluated and optimized. In the next step, the validation of the new method have been performed, finding it to be specific in the trace analysis of PAHs, with the limit of detection (LOD) ranging from 0.01 to 0.5 μg L(-1) and the linear range from the respective LOD to 200 μg L(-1) with RSD amounting to less than 8%. The thermal stability of the fibers was investigated as well and they were found to be durable at 280°C for 345 min. Furthermore, the proposed method was successfully applied for quantification of PAHs in real water samples.

Novel solid-phase microextraction fibers were prepared based on sol–gel technique. Commonly used fused silica substrate was replaced by titanium wire which provided high strength and longer fiber life cycle. Titanium isopropoxide was employed as the precursor which provides a sol solution containing Ti–OH groups and shows more tendencies to the molecularly similar group on the substrate. Three different polymers, poly (dimethylsiloxane) (PDMS), poly(ethylenepropyleneglycol)-monobutyl ether (Ucon) and polyethylene glycol (PEG) were employed as coating polymer in preparing three different fibers. The applicability of these fibers was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water sample followed by gas chromatography–mass spectrometry (GC–MS). Effects of different parameters such as fiber coating type, extraction condition, desorption condition were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.75–10 μg L −1 (S/N = 3) and 1–20 μg L −1 (S/N = 10) were respectively obtained. The method showed linearity in the range of 10–25,000 μg L −1 with correlation coefficient of >0.99. The relative standard deviation was less than 8%.

A method based on solid-phase microextraction (SPME) followed by on-fiber derivatization and gas chromatography–mass spectrometry detection (GC–MS) for determination of phenol in air was developed. Three different types of SPME fibers, polar and non-polar poly(dimethylsiloxane) (PDMS) and polyethylene glycol (PEG) were synthesized using sol–gel technology and their feasibility to the sampling of phenol were investigated. Different derivatization reagents for post on-fiber derivatization of phenol were studied. Important parameters influencing the extraction and derivatization process such as type of fiber coating, type and volume of derivatizing reagent, derivatization time and temperature, extraction time, and desorption conditions were investigated and optimized. The developed method is rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Under the optimized conditions, the detection limit of the method was 5 ng L −1 using selected ion monitoring (SIM) mode. The inter-day and intra-day precisions of the developed method under optimized conditions were below 10%, and the method shows linearity in the range of 20 ng L −1 to 500 μg L −1 with the correlation coefficient of >0.99. The optimized method was applied to the sampling of phenol from some biologics production areas. The compared results obtained using current and standard methods were shown to be satisfactory.

Reinforced polydiphenylamine (PDPA) nanocomposite was synthesized by oxidation of diphenylamine in 4 molL(-1) sulfuric acid solution containing a fixed amount of carbon nanotubes (CNTs) in the presence of cetyltrimethylammonium bromide (CTAB). The surface characteristic of PDPA and PDPA/CNT nanocomposites was investigated using scanning electron microscopy (SEM). The prepared PDPA/CNT nanocomposite was used as an extraction medium for microextraction in packed syringe (MEPS) of selected pesticides from aquatic environment. The effect of CNT doping level and the presence of surfactant on the extraction capability of nanocomposite was investigated and it was revealed that when 4% (w/w) of CNT in the presence of CTAB is being used, the highest extraction recovery could be achieved. Eventually, the developed MEPS technique in off-line combination with gas chromatography-mass spectrometry (GC-MS) was applied to the analysis of some pesticides including triazine, organophosphorous, organochlorine and aryloxyphenoxy propionic acid pesticides. Important parameters influencing the extraction and desorption processes were optimized and a 25 cycles of draw-eject gave maximum peak area, when desorption was performed using 200 μL of n-hexane. Limits of detection (LODs) were in the range of 0.01-0.1 ngmL(-1) and 0.02-0.1 ngmL(-1) for distilled water and river water respectively, using time scheduled selected ion monitoring (SIM) mode. The method precision (RSD %) with four replicates was in the range of 1.6-14.6% for distilled water and 1.5-16.2% for river water at the concentration level of 5 ngmL(-1) while the linearity of method was in the range of 0.15-100 and 0.5-500 ngmL(-1). The developed method was successfully applied to different river water samples and the matrix factor for the spiked river water samples were found to be in the range of 0.74-1.09.

An immersed single drop microextraction (SDME) method was successfully developed for the trace enrichment of formaldehyde from DTP and DT vaccines and diphtheria-tetanus antigen. The formaldehyde was derivatized by means of the Hantzsch reaction. The dehydropyridine derivative was extracted into a microdrop of chloroform that suspended in a 4 ml sample solution for a preset time. The microdrop was then retracted into the microsyringe and injected directly into a gas chromatography-mass spectrometry (GC-MS) injection port. Effects of different parameters such as the type of solvent, extraction time, stirring rate, and temperature were studied and optimized. The limit of detection was 0.22 ng/l and relative standard deviation (RSD) value was 6.2% (n=5). The regression coefficient was satisfactory (r(2)=0.992) and linear range was obtained from 1 to 500 ng/l.

A modified solvent microextraction with back extraction method (SME/BE) combined with high performance liquid chromatography and fluorescence detection (HPLC-FD) was developed for the determination of citalopram in human plasma. Extraction process was performed in a home-made total glass vial without using a teflon ring, usually employed in SME/BE. Citalopram was first extracted from 0.5 mL of plasma, modified with sodium hydroxide, into hexane. Back extraction step was then performed into 5.2 μL of 45 mM ammonium formate solution (pH 4) using a GC microsyringe. The extract was subsequently transferred into a liner-like vial and then injected into the HPLC system. An enrichment factor of 150 along with a good sample clean-up was obtained. The calibration curve showed linearity in the range of 1.0–130.0 ng mL−1 with regression coefficient corresponding to 0.992. This range covers therapeutic window and even lower amounts which is important in pharmacokinetic studies. Limits of detection and quantification, based on a signal to noise ratio (S/N) of 3 and 10, were 0.3 and 0.8 ng mL−1, respectively. The method was also applied for the determination of citalopram in plasma samples after oral administration of 40 mg single dose of citalopram.

Solid-phase microextraction probes based on poly(ethylene glycol)/C18-bonded silica were used for in vivo monitoring of drugs from circulating blood of beagles, over a period of 8 h. After sampling, the extracted drugs were subsequently quantified by liquid chromatography coupled with tandem mass spectrometry. External calibrations in whole blood and phosphate-buffered saline were used to correlate the amount of analytes extracted in regard to the total and free concentrations in blood respectively. The probe provided sufficient sensitivity for the drugs in the blood matrix, while the need for drawing blood was eliminated. The limit of detections of the method from whole blood were 1.7, 1.4 and 2.8 ng mL(-1) for the analysis of diazepam, nordiazepam and oxazepam respectively, and the linear range was from 4 ng mL(-1) to 2 microg mL(-1). The method was applied for the monitoring of pharmacokinetic profiles of intravenous administration of diazepam and its two main metabolites in dogs, and the results were compared with profiles determined by conventional methods. This approach offered increased sensitivity and accuracy, short extraction time, and convenient calibration for in vivo sampling for dynamic monitoring.

An integrated microsampling approach based on solid-phase microextraction (SPME) was developed to provide a complete solution to highly efficient and accurate pharmacokinetic studies. The microsampling system included SPME probes that are made of poly(ethylene glycol) (PEG) and C18-bonded silica, a fast and efficient sampling strategy with accurate kinetic calibration, and a high-throughput desorption device based on a modified 96-well plate. The sampling system greatly improved the quantitative capability of SPME in two ways. First, the use of the C18-bonded silica/PEG fibers minimized the competition effect from analogues of the target analytes in a complicated sample matrix such as blood or plasma samples, which is a common problem associated with solid coating SPME fibers for quantitative analysis. Moreover, the C18-bonded silica/PEG fibers provide high sensitivity and a large dynamic range that covers the possible sample concentration range during diazepam administration and elimination. Second, the kinetic calibration method offers more accurate quantitation than the calibration curve method for in vivo SPME, because it compensates for convection and matrix effects during sampling. Therefore, it is especially suitable as a fast sampling technique for pre-equilibrium SPME. Furthermore, with the high-throughput desorption device, the integrated system offers compactness and high efficiency. Its feasibility for in vivo sampling was demonstrated by monitoring diazepam pharmacokinetics and validated by conventional chemical assays and equilibrium SPME. In addition, we propose a simple method to determine the apparent distribution constant between an SPME fiber and a blood matix (Kfs) and the distribution constant between an SPME fiber and a pure PBS buffer sample matrix (Kfb). As a result, both total and free concentrations of the drug and its metabolites can be detected simultaneously. Accordingly, the binding constants to the blood matrix can be obtained, which are of special significance for clinical diagnosis and drug discovery.

A head-space solid-phase microextraction (HS-SPME) method coupled to GC–MS was developed to extract fentanyl from human plasma. The protein binding was reduced by acidification and, eventually, the sample was deproteinized with trichloroacetic acid. The parameters influencing adsorption (extraction time, temperature, pH and salt addition) and desorption (desorption time and temperature) of the analyte on the fibre were investigated and validated for method development. The developed method proved to be rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Linear range was obtained from 0.1 ng/ml to 2 μg/ml. The limit of detection was 0.03 ng/ml while an inter-day precision of less than 5% ( n = 15) could be achieved. The method has been applied for the determination of fentanyl in plasma samples after application of 50 μg/h Duragesic fentanyl patch.

A novel solid-phase microextraction (SPME) method was developed for isolation of dextromethorphan (DM) and its main metabolite dextrorphan (DP) from human plasma followed by GC-MS determination. Three different polymers, poly(dimethylsiloxane) (PDMS), poly(ethylenepropyleneglycol) monobutyl ether (Ucon) and polyethylene glycol (PEG) were synthesized as coated fibers using sol-gel methodologies. DP was converted to its acetyl-derivative prior to extraction and subsequent determination. The porosity of coated fibers was examined by SEM technique. Effects of different parameters such as fiber coating type, extraction mode, agitation method, sample volume, extraction time, and desorption condition, were investigated and optimized. The method is rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. The limits of detection are 0.010 and 0.015 ng/ml for DM and DP, respectively. The precisions for both analytes are below 5% (n=5). The correlation coefficient was satisfactory (r(2)>0.99) for both DM and DP. Linear ranges were obtained from 0.03 ng/ml to 2 microg/ml for DM and from 0.05 ng/ml to 2 microg/ml for DP.

A new and convenient format of single drop microextraction (SDME) was developed and applied for isolation of some selected aryloxyphenoxypropionate herbicides from aquatic media. In contrast to the conventional SDME procedure, in this set-up the extraction microdrop was positioned at the bottom of a conical vial in order to provide much higher stability for the organic extraction phase while a magnetic bar was used for stirring the aqueous solution. A simple magnet was used for positioning the bar on the top of the microdrop prior to stirring. The whole set-up led to the use of any volume of extraction solvent with unlimited stirring rates. Some important extraction parameters such as the type of solvent, stirring rate, temperature and extraction time were investigated and optimized. Selection of a microdrop volume of 3 μL with a sampling time of 35 min along with the use of carbon tetrachloride as the most appropriate solvent led to the highest enrichment factors. The linearity was studied by preconcentration of 1 mL of water samples spiked with a standard solution of aryloxyphenoxypropionates in the concentration range of 0.1–300 μg L−1. The coefficient of determination was satisfactory (r2 > 0.99) for all the studied analytes and the relative standard deviation (RSD%) values under the optimized conditions were found to be in the range of 5.1 to 10.1% at the concentrations of 0.6 and 50 μg L−1. Detection limits were obtained to be in the range of 0.02–0.05 μg L−1 using time-scheduled selected ion monitoring (SIM). The developed method was successfully applied for the extraction and determination of aryloxyphenoxypropionates in river water samples.

A horizontally oriented liquid–liquid–liquid microextraction (HOLLLME) setup was developed and applied for the isolation of two major estrogens from aquatic media. In contrast to the conventional procedure, in this setup the extracting microdrop was suspended from a horizontally positioned needle in order to provide much higher stability to the extracting phase. The developed HOLLLME approach was applied to isolate two major selected estrogens from aquatic media followed by high performance liquid chromatography-ultraviolet (HPLC-UV) determination. Estrogens were, initially, extracted from water samples into hexane and subsequently, the back extraction stage was performed with 6 μL of sodium hydroxide solution suspended from a horizontally fixed GC microsyringe tip. Important parameters influencing the extraction process were optimized and an extraction time of 25 min, back extraction time of 5 min, temperature of 35 °C, pH of 6 for a donor phase, dropsize of 6 μL and organic phase volume of 300 μL were achieved as optimum values. The enrichment factors of 111 for estrone and 80 for estriol were obtained at 1 mg L−1 concentration. The calibration curves showed linearity in the range of 10–500 μg L−1 with coefficients of determination higher than 0.99. The limits of detection and quantification were 3 and 10 μg L−1, respectively. Under optimized conditions, the relative standard deviation percent (RSD%) values were found to be from 6.8 to 13.0. Two typical surface water samples were used to assay the validation of the developed method.