An electrospun polyethylene terephthalate/graphene oxide nanofibrous mat was fabricated and used as an effective and novel membrane for the solid-phase extraction of tamoxifen in human blood plasma samples before detection by high-performance liquid chromatography. The membrane was characterized by some identification techniques, such as FTIR spectroscopy, X-ray diffraction, and scanning electron microscopy. The effective variables of the extraction procedure including desorption condition (type and volume of the eluent), adsorbent dose, pH of sample solution, salt concentration, and sample loading time were investigated and their optimum values were obtained using one factor at a time methodology. Under the optimized conditions, the results showed wide linear concentration range of 5-2000 ng/mL with a determination coefficient of 0.992. The limits of detection and limits of quantification were 1.3 and 5.0 ng/mL, respectively. The intra-day and inter-day precisions were 3.4 and 4.6%, respectively. The method was successfully applied to determination of tamoxifen in the blood plasma samples and satisfactory relative recoveries (92.6-98.3 %) were achieved.
A solution of polyamide (PA) containing polyethylene glycol (PEG) as a side low-molecular-weight polymer was electrospun. After synthesizing the PA-PEG nanofibers, the constituent was subsequently removed (modified PA) and confirmed by Fourier transform infrared spectroscopy. The scanning electron microscopy images showed an average diameter of 640 and 148 nm for PA and PA-PEG coatings, respectively, while the latter coating structure was more homogeneous and porous. The extraction efficiencies of PA, PA-PEG, and the modified PA fiber coatings were assayed by headspace solid-phase microextraction of a number of chlorophenols from real water samples followed by their determination by gas chromatography with mass spectrometry. To prepare the most appropriate coatings, the amounts and the flow rate of the electrospinning solution were investigated. Various extraction parameters, such as the salt content, desorption condition, extraction temperature, and time were optimized. The limits of detection of the method were in the range of 0.8-25 ng/L, while the RSDs at two concentration levels of 200 and 80 ng/L were between 2.1 and 12.2%. The analysis of real water samples led to relative recoveries between 85 and 98% with a linearity of 8-1500 ng/L.
A novel electrospun composite nanofiber-based adsorbent (polyurethane/polystyrene-silica) was fabricated, characterized, and used in the headspace solid-phase microextraction of the acetylated derivatives of chlorophenols in water samples before gas chromatography with micro electron capture detection. The surface morphology, chemical composition, thermal stability, and structure of the fibers were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Brunauer-Emmett-Teller and Barrett-Joyner-Halenda techniques. The effect of the main parameters influencing the efficiency of the method including extraction temperature, salt concentration, and extraction time was investigated and the optimized conditions were obtained. The linear dynamic ranges were 0.1-800 ng/mL. The relative standard deviations (n = 3) and the limits of detection were 2.64-9.57% and 0.0234-0.830 ng/mL, respectively. The relative recoveries for real samples (river water and sewage of our university campus) were between 90.8 and 111%.
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