Fe(3)O(4)/polyethylene glycol nanocomposite as a solid-phase microextraction fiber coating for the determination of some volatile organic compounds in water.

A high-performance metal oxide polymer magnetite/polyethylene glycol nanocomposite was prepared and coated in situ on the surface of the optical fiber by sol-gel technology. The magnetite nanoparticles as nanofillers were synthesized by a coprecipitation method and bonded with polyethylene glycol as a polymer. The chemically bonded coating was evaluated for the headspace solid-phase microextraction of some environmentally important volatile organic compounds from aqueous samples in combination with gas chromatography and mass spectrometry. The prepared fiber was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The mass ratio of nanofiller and polymer on the coating extraction efficiency, morphology, and stability were investigated. The parameters affecting the extraction efficiency, including the extraction time and temperature, the ionic strength, desorption temperature, and time were optimized. The sol-gelized fiber showed excellent chemical stability and longer lifespan. It also exhibited high extraction efficiency compared to the two types of commercial fibers. For volatile organic compounds analysis, the new fiber showed low detection limits (0.008-0.063 ng/L) and wide linearity (0.001-450 × 104 ng/L) under the optimized conditions. The repeatability (interday and intraday) and reproducibility were 4.13-10.08 and 5.98-11.61%, and 7.35-14.79%, respectively (n = 5). For real sample analysis, three types of water samples (ground, surface, and tap water) were studied.

Physical Training Status Determines Oxidative Stress and Redox Changes in Response to an Acute Aerobic Exercise.

Objective. To assess the influence of different physical training status on exercise-induced oxidative stress and changes in cellular redox state. Methods. Thirty male subjects participated in this study and were assigned as well-trained (WT), moderately trained (MT), and untrained (UT) groups. The levels of cortisol, creatine kinase, plasma reduced glutathione to oxidized glutathione (GSH/GSSG), cysteine/cystine (Cys/CySS), and GSH/GSSG ratio in red blood cells (RBCs) were measured immediately and 10 and 30 min after exercise. Results. Following the exercise, plasma GSH/GSSG (p = 0.001) and Cys/CySS (p = 0.005) were significantly reduced in all groups. Reduction in plasma GSH/GSSG ratio in all groups induced a transient shift in redox balance towards a more oxidizing environment without difference between groups (p = 0.860), while RBCs GSH/GSSG showed significant reduction (p = 0.003) and elevation (p = 0.007) in UT and MT groups, respectively. The highest level of RBCs GSH/GSSG ratio was recorded in MT group, and the lowest one was recorded in the WT group. Conclusion. Long term regular exercise training with moderate intensity shifts redox balance towards more reducing environment, versus intensive exercise training leads to more oxidizing environment and consequently development of related diseases.

All-in-one solid-phase microextraction: Development of a selective solid-phase microextraction fiber assembly for the simultaneous and efficient extraction of analytes with different polarities.

In the present work, for the first time, an all-in-one solid-phase microextraction technique was developed for the simultaneous and efficient extraction of analytes within a vast polarity range. A novel fiber assembly composed of two different steel components each coated with different coatings (polydimethylsiloxane and polyethylene glycol) in terms of polarity by sol-gel technology was employed for the extraction of model compounds of different polarity in a single run followed by gas chromatography with mass spectrometry. Effective parameters in the extraction step and gas chromatography with mass spectrometry analysis were optimized for all model compounds. The detection limits of the developed method for model compounds were below 0.2 ng/L. The repeatability and reproducibility of the proposed method, explained by relative standard deviation, varied between 7.22 and 9.15% and between 7.95 and 14.90 (n = 5), respectively. Results showed that, under random conditions, compared to separate extractions performed by two other differently end-coated components that had not been assembled as the final dual fiber, as two individual fibers; simultaneous, efficient and relatively selective extraction of all model compounds was obtained in a single run by the proposed all-in-one technique. Finally, the optimized procedure was applied to extraction and determination of the model compounds in spiked water samples.

Polyvinylimidazole/sol-gel composite as a novel solid-phase microextraction coating for the determination of halogenated benzenes from aqueous solutions.

A polyvinylimidazole/sol-gel composite is proposed as a novel solid-phase microextraction fiber to extract five halobenzenes from the headspace of aqueous solutions in combination with gas chromatography with mass spectrometry. The prepared fiber was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The obtained results showed that porous polyvinylimidazole/sol-gel composite was chemically deposited on fused silica fiber. The effect of important extraction parameters including extraction temperature, extraction time, and salt content were investigated. The optimum conditions were as follows: extraction temperature 25°C, extraction time 20 min, and salt concentration 30 w/v%. Detection limits and relative standard deviations of the developed method for halogenated benzenes were below 0.1 pg/mL and 15%, respectively. Repeatability of the proposed method, explained by relative standard deviation, varied between 5.48 and 9.15% (n = 5). The limits of detection (S/N = 3) ranged between 0.01 and 0.10 ng/L using gas chromatography with mass spectrometry with selected ion monitoring mode. For real sample analysis, three types of water samples with different matrices (ground, surface, and tap water) were studied. The optimized procedure was applied to extraction and method validation of halogenated benzenes in spiked water samples.

Enhanced thebaine production in Papaver bracteatum cell suspension culture by combination of elicitation and precursor feeding.

In this study, the effect of methyl jasmonate (MJ) and ultrasound (US), individually and in combination with L-tyrosine, on the stimulation of thebaine production in Papaver bracteatum cell suspension cultures was studied. The addition of L-tyrosine did not significantly affect the cell biomass, but significantly increased the thebaine yield of cells compared with the control. The synergistic effects of MJ and L-tyrosine in the combined treatment of 100 µM MJ and 2 mM L-tyrosine increased the thebaine yield of cells up to 84.62 mg L(- 1) at 6 days after treatment. Sonication of the cells for 20 s caused a significant decrease in cell growth and biomass, whereas the thebaine yield increased up to 39.60 mg L(- 1) at 6 days after treatment. The combination of US (10 s) and L-tyrosine feeding (2 mM) significantly increased the production of thebaine in comparison to individual utilisation of 2 mM L-tyrosine and US (10 s).