Simultaneous determination of methadone and tramadol in serum samples by ultrasonic-assisted micro solid phase extraction and gas chromatography-mass spectrometry.

Ultrasonic-assisted dispersive micro solid phase extraction (UA-DMSPE) is proposed as a fast and easy technique for the extraction and preconcentration of methadone and tramadol from serum samples. Different sorbents including carbon nanotubes, oxidized carbon nanotubes, and TiO2 nanoparticles were compared to extract methadone and tramadol. The best performance was obtained using oxidized carbon nanotubes due to the strong affinity between the drugs and carbon nanotube adsorbents. Final analysis of drugs performed by using gas chromatography-mass spectrometric detection. Different parameters affecting the extraction efficiency, such as the sample volume, amount of adsorbent, desorption solvent type and volume, centrifugation time, and speed were investigated and optimized. The striking features of this technique are correlated to its speed and the small volumes of sample (about 1 mL), desorption solvent (about 50 µL), and adsorbent (about 0.001 g) for analysis of drugs, and finally, milder centrifugation conditions relative to the previously reported adsorbent. The optimal parameters were achieved as follows: pH value was set at 9, the sample volume was adjusted to 1200 µL, the amount of adsorbent used was 1 mg, the extraction time was set at 5 min, and the volume of the desorption solvent was adjusted to 50 µL. The limits of detections (0.5 and 0.8 ng mL-1) and quantifications (1.5 and 2.5 ng mL-1) were obtained for methadone and tramadol, respectively. The developed method also showed good repeatability, relative standard deviation (RSD) of 9.49 % and 7.47 % (n = 5), for the spiked aqueous solution at the concentration level of 10, 50, and 100 ng mL-1 for analytes, and linearity, R ≥ 0.9809. The results showed that UA-DMSPE is a quick, relatively inexpensive, and environmentally friendly alternative technique for the extraction of opiate drugs from serum samples.

Pharmacokinetic study and the extraction efficiency of bulk and precipitated ibuprofen-imprinted polymer sorbents for gas chromatography and gas chromatography-mass spectrometry ibuprofen bio-analysis.

Bulk and precipitation polymerization methods were used to prepare ibuprofen-molecularly imprinted polymers. Molecularly imprinted polymer-bulk and -precipitation were synthesized in acetonitrile, likewise molecularly imprinted polymer-bulk (mixture) and molecularly imprinted polymer-precipitation (mixture) in a mixture of acetonitrile/toluene (75:25 v/v). N2 adsorption-desorption analysis data revealed that molecularly imprinted polymer-precipitation (mixture) has the highest specific surface area (200.74 m2 /g). The surface chemistry and morphology of the synthesized sorbents were investigated by Fourier-transform infrared analysis and scanning electron microscope micrographs respectively. The prepared sorbents in the mixture of solvents were used in a dispersive solid-phase extraction process for selective extraction and pre-concentration of ibuprofen from urine and human plasma samples. The detection limits were 62.91 and 7.89 ng/ml using molecularly imprinted polymer-bulk (mixture) and molecularly imprinted polymer-precipitation (mixture), respectively. Also, the sorbents showed selective behavior to extract ibuprofen in the presence of naproxen, fenoprofen, and ketoprofen. Overall, the results showed that the precipitation method in the mixture of acetonitrile/toluene resulted in the preparation of a sorbent with the highest extraction efficiency. Furthermore, a pharmacokinetic study was done. The maximum plasma concentration, the time required for maximum plasma concentration, and plasma half-life were 28.95 µg/ml, 2, and 2.39 h, respectively.

Polybutylene succinate/modified cellulose bionanocomposites as sorbent for needle trap microextraction.

In this work, different polybutylene succinate/modified cellulose bio-nanocomposites were synthesized by solving the casting method and then used as a new sorbent for needle trap microextraction of some polycyclic aromatic hydrocarbons from the water samples in headspace mode. The surface of cellulose nanocrystalline was modified using aminosilane groups to improve the dispersion of nanoparticles in the polybutylene succinate matrix. The characterization of synthesized nanocomposites, were performed using TGA, SEM, BET analysis and FT-IR spectroscopy. Adding modified nanocrystalline cellulose to a polybutylene succinate matrix increased the surface area, and thermal and mechanical stabilities. The significant parameters of the sorbent extraction process, including the amount of modified cellulose nanoparticles, the extraction time, and temperatures and salt content, were studied and optimized. Under the optimized extraction conditions (extraction time of 25 min, and extraction temperature of 50 °C), an analytical method for selected polycyclic aromatic hydrocarbons with low detection limits (0.75-1 ng L-1) and the quantification limit (3-5 ng L-1), good repeatability (3-7% at 20 ng L-1), and reproducibility (9%-14%, n = 3) was developed. The linearity of the method was obtained in the range of 5-1000 ng L-1 with R2 > 0.9996. The enrichment factor was obtained for the spiked real aqueous samples (at 50 ng L-1) in the range of 276-311. Also, the performance of the developed method was studied via the extraction of selected analytes in real water samples, and the relative recovery values were found to be in the range of 98-103%.

Modified activated carbon derived from chestnut oak shells as a new sorbent for the needle-trap extraction.

In this study, an acid-treated-activated carbon was prepared from chestnut oak shell carbonization followed by modification with hydrochloric acid/nitric acid and then used as a new sorbent for headspace needle-trap extraction of chlorophenol compounds from aqueous solutions. Different techniques, including scanning electron microscopy, nitrogen adsorption-desorption analysis, and Fourier transform-infrared spectroscopy were used for the characterization of the sorbents. The effects of some experimental parameters, including the temperature, pH, sorbent amount, and time of extraction were optimized. The developed method is fast and sensitive, providing low and sub ng/L detection limits. The limits of detection and quantification were in the range of 0.75-5 and 5-15 ng/ml, respectively, and the equilibrium time was 20 min. Wide linearity in the range of 15-2000 ng/L with R2  > 0.9993 was obtained. Repeatability of the method was accessed at 50, 100, and 200 ng/L concentration levels and RSD% of 5%-12% was achieved. The introduced method was applied for analyzing real water samples containing spiked chlorophenols, and the relative recovery values were found to be in the range of 84%-99% at the concentration levels of 50, 100 and 200 ng/L.

Electroless deposition of silver nanofractals on copper wire by galvanic displacement as a simple technique for preparation of porous solid-phase microextraction fibers.

A novel and porous solid-phase microextraction fiber was prepared by quick and simple galvanic displacement reaction and applied to the determination of some polycyclic aromatic hydrocarbons in sunflower oil. The parameters affecting the porosity and thickness of the fiber, and parameters affecting the extraction efficiency, including the extraction time, temperature, and ionic strength, were investigated and optimized. The morphology of prepared fiber was characterized by optical and scanning electron microscopy and thermal and chemical stabilities of the fiber were studied. Under the optimum conditions, the limits of detection ranged between 0.1 ng/mL for pyrene to 1.2 ng/mL for anthracene, and LOQ ranged between 0.3 ng/mL for pyrene to 3.6 ng/mL for anthracene. The relative standard deviations, including repeatability (within fibers) and reproducibility (between fibers), varied between 3.2-8.9 and 5.6-9.8%, respectively.

Improvement of solid-phase microextraction efficiency by the application of a carbon-nanotubes-based ternary microextraction fiber composite.

In this study, a novel technique is proposed for preparation of an efficient and unbreakable metal-wire-supported solid-phase microextraction fiber. A sol-gel film was deposited on electrophoretically deposited carbon nanotubes on a stainless-steel wire. The applicability of the fiber was evaluated through the extraction of some aromatic pollutants as model compounds from the headspace of aqueous samples in combination with gas chromatography and mass spectrometry. The parameters affecting the structure and extraction efficiency of the fiber (including the type of solvent, time, and potential for electrophoretic deposition) and the parameters affecting the extraction efficiency (such as coating type, salt content, extraction temperature, and time) were investigated. The results showed that the film thickness will be increased by increasing the potential and time duration. Finally, the characterization of the deposited film was accomplished by scanning electron microscopy and thermogravimetric analysis. After the optimization of the extraction parameters, the limit of detection of less than 20 pg/mL was achieved, and the calibration curves were all linear (r2  ≥ 0.9737), in the range from 50 to 500 pg/mL. The solid-phase microextraction fiber has a high mechanical strength; good stability and long service life, making it potentially applicable in the extraction of trace polycyclic aromatic hydrocarbons from aqueous samples.

Solid-phase nanoextraction of polychlorinated biphenyls in water and their determination by gas chromatography with electron capture detector.

A solid-phase nanoextraction method has been developed for the extraction and preconcentration of polychlorinated biphenyls using carboxyl multiwalled carbon nanotubes as a solid nano-sorbent. Parameters affecting extraction efficiency such as sorbent amount, desorption solvent type and volume, extraction time, pH, and salt content have been studied. Under optimized conditions, the correlation coefficient was up to 0.9989, the limits of detection was in the range of 1.4-3.5 ng/L, and limits of quantification was between 4.8 and 11.6 ng/L. The recoveries were in the range of 99-106% for different spiked analytes. The relative standard deviation for water samples spiked with two different spiking levels has been between 4 and 10%. The proposed sustainable method is rapid, easy to use, and small consumption of organic solvent for the detection and determination of trace levels of polychlorinated biphenyls in environmental waters.

Solid-phase microextraction of methadone in urine samples by electrochemically co-deposited sol-gel/Cu nanocomposite fiber.

Electrochemically co-deposited sol-gel/Cu nanocomposites have been introduced as a novel, simple and single-step technique for preparation of solid-phase microextraction (SPME) coating to extract methadone (MDN) (a synthetic opioid) in urine samples. The porous surface structure of the sol-gel/Cu nanocomposite coating was revealed by scanning electron microscopy. Direct immersion SPME followed by HPLC-UV determination was employed. The factors influencing the SPME procedure, such as the salt content, desorption solvent type, pH and equilibration time, were optimized. The best conditions were obtained with no salt content, acetonitrile as desorption solvent type, pH 9 and 10 min equilibration time. The calibration graphs for urine samples showed good linearity. The detection limit was about 0.2 ng mL-1 . Also, the novel method for preparation of nanocomposite fiber was compared with previously reported techniques for MDN determination. The results show that the novel nanocomposite fiber has relatively high extraction efficiency.

A single step technique for preparation of porous solid phase microextraction fibers by electrochemically co-deposited silica based sol-gel/Cu nanocomposite.

In this study, electrochemically co-deposited 3-trimethoxysilyl propyl methacrylate (3TMSPMA)/Cu nanocomposite is introduced as a novel and single-step technique for preparation of efficient and unbreakable solid phase microextraction (SPME) fibers; having strong interaction between the substrate and the coating. The applicability of prepared nanocomposite films was evaluated through extraction of some aromatic pollutants as model compounds from the headspace of aqueous samples in combination with gas chromatography-mass spectrometry (GC-MS). Different parameters affecting the structure and composition of the deposited films including applied potential, electrodeposition time, and precursor concentration; and the parameters affecting extraction efficiency such as extraction temperature, extraction time, and salt content were investigated. The results showed that morphology and grain size of the films are strongly affected by the ratio between the sol-gel precursor and Cu(2+) ions. Furthermore, potential of deposition influences the composition of films as it controls the kinetics of sol-gel/Cu co-deposition. Finally, characterization of the deposited films was accomplished by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA).

A novel strategy to increase performance of solid-phase microextraction fibers: electrodeposition of sol-gel films on highly porous substrate.

In the present work, the effect of substrate porosity for preparation of solid-phase microextraction (SPME) fibers was investigated. The fibers were prepared by electrodeposition of sol-gel coatings using negative potentials on porous Cu wire and compared with previous reported technique for preparation of SPME fibers using positive potentials on smooth gold wire. Porous substrate was prepared by electrodeposition of a thin layer of Cu on a Cu wire. The extraction capability of prepared fibers was evaluated through extraction of some aromatic hydrocarbons from the headspace of aqueous samples. The effect of substrate porosity and some operating parameters on extraction efficiency was optimized. The results showed that extraction efficiency of SPME fibers highly depends on porosity of the substrate. The LOD ranged from 0.005 to 0.010 ng/mL and repeatability at the 1 ng/mL was below 12%. Electrodeposited films were characterized for their surface morphology and thermal stability using SEM and thermogravimetric analysis, respectively. SEM analysis revealed formation of porous substrate and subsequently porous coating on the wire surface and thermogravimetric analysis showed high thermal stability of the prepared fiber.