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141.
Kaige Zhang Shuangying Li Chuang Liu Qi Wang Yunhe Wang Jing Fan 《Journal of separation science》2019,42(2):574-581
In recent years, hydrophobic deep eutectic solvents as new generation of green solvents have attracted wide attention in liquid microextraction technique. In this article, four hydrophobic deep eutectic solvents composed of trioctylmethylammonium chloride and oleic acid were designed and prepared firstly. Combined with high‐performance liquid chromatography, these deep eutectic solvents were used as an extraction solvent in vortex‐assisted dispersive liquid–liquid microextraction for the selective enrichment and indirect determination of trace nitrite from real water and biological samples. This method is based on the diazotization‐coupling reaction of nitrite with p‐nitroaniline and diphenylamine in acidic water, and then the nitrite is quantified indirectly by measuring the obtained azo compounds. Some factors influencing the extraction efficiency, including the reaction and extraction conditions, were investigated. Under the optimized conditions, the method has a linear range of 1–300 μg/L with a correlation coefficient of 0.9924, limit of detection of 0.2 μg/L, limit of quantitation of 1 μg/L, intraday and interday relative standard deviations of 4.0 and 6.0%. This method was successfully applied in determination of nitrite from three environmental water and two biological samples with the recovery in the range of 90.5–115.2%. In addition, these results were well agreement with those obtained by the conventional Griess method. 相似文献
142.
Mohammad Reza Kashefi Alasl Mahmoud Reza Sohrabi Mehran Davallo 《Journal of separation science》2019,42(9):1777-1785
In this work, a fast and simple magnetic dispersive solid phase extraction methodology was developed utilizing Ag@magnetite nanoparticles@graphene nanocomposite as an efficient magnetic nanosorbent for preconcentration and determine of five aromatic amines in water samples. The sorbent was characterized by diverse characterization techniques. After the extraction, high‐performance liquid chromatography with UV detection was utilized to analysis the aromatic amines. The effects of different factors on the extraction process were studied thoroughly via design of experiment and desirability function. Detection limits and linear dynamic ranges were obtained in the range of 0.10–0.20 and 0.3–300 μg/L, respectively. The relative standard deviations (n = 5) were in the range of 4.3–6.5%. Eventually, the method was employed for determination of target aromatic amines in various water samples. 相似文献
143.
This study presents a simple and green dispersive micro‐solid phase extraction method for preconcentration of acidic quinolones from honey prior to high performance liquid chromatography determination. A two‐dimensional nanostructured zinc‐aluminum layered double hydroxide was synthesized and used as the sorbent for dispersive micro‐solid phase extraction. Its different characteristics from conventional sorbents is that it is dissolvable in acidic solution (pH < 4). After the extraction, the analyte elution step was omitted and thus the use of organic solvents was avoided. The key parameters influencing the extraction efficiency such as the amount of sorbent, pH of sample solution, vortex time, type and volume of acidic solution were investigated and optimized. The method exhibited low limits of detection (3.0?5.0 ng/g), good linearity (10?2000 ng/g) with coefficients of determinations higher than 0.9991, acceptable precision (RSD<9.1%) and accuracy (RE<5.8%). The proposed method is fast, efficient, eco‐friendly, and suitable for the determination of acidic quinolones in honey samples. 相似文献
144.
Mohammadali Torbati Mir Ali Farajzadeh Mohammad Reza Afshar Mogaddam Mostafa Torbati 《Journal of separation science》2019,42(9):1768-1776
A homogeneous liquid‐liquid extraction performed in narrow tube coupled to in–syringe‐dispersive liquid‐liquid microextraction based on deep eutectic solvent has been developed for the extraction of six herbicides from tea samples. In this method, sodium chloride as a separation agent is filled into the narrow tube and the tea sample is placed on top of the salt. Then a mixture of deionized water and deep eutectic solvent (water miscible) is passed through the tube. In this procedure, the deep eutectic solvent is realized as tiny droplets in contact with salt. By passing the droplets from the tea layer placed on the salt layer, the analytes are extracted into them. After collecting the solvent as separated layer, it is mixed with another deep eutectic solvent (choline chloride/butyric acid) and the mixture is dispersed into deionized water placed in a syringe. After adding acetonitrile to break up the cloudy state, the collected organic phase is injected into gas chromatography‐mass spectrometry. Under optimal conditions, limits of detection and quantification in the ranges of 2.6–8.4 and 9.7–29 ng/kg, respectively, were obtained. The extraction recoveries and enrichment factors in the ranges of 70–89% and 350–445 were obtained, respectively. 相似文献
145.
Barbara Benedetti Emanuele Magi Marina Di Carro 《Journal of separation science》2019,42(20):3225-3233
The present paper deals with the multivariate optimization of an extraction‐purification strategy for the determination of phytoestrogens (daidzein, genistein, coumestrol, formononetin, and biochanin A) in soy‐based meat substitutes by high performance liquid chromatography with tandem mass spectrometry. For a reliable quantitation of these new concerning compounds in such a complex matrix, recovery and matrix effect must be carefully evaluated. Therefore, two sequential experimental designs were used to optimize the sample‐pretreatment of soy‐based burgers: the chosen technique was the quick, easy, cheap, effective, rugged and safe methodology, which does not require any particular facility or instrumentation. Thanks to the first screening design (Plackett‐Burman), the significant factors influencing the studied responses were identified and further investigated through a response surface design (Box‐Behnken). The optimal values of the variables (volume of extraction solvent mix/sample mass ratio and two clean‐up sorbents) led to quantitative recoveries (97–104%) and low ion suppression (matrix effect 60–93%) for all analytes. This optimized method was characterized by low detection limits (0.2–1.5 ng/g) and excellent intraday precision (RSD 2–4%). It was applied to the determination of the considered compounds in several soy‐burgers from the Italian market, detecting low ng/g levels (up to 40 ng/g) of coumestrol, formononetin, and biochanin A, and high concentrations (7.9–78 µg/g) of genistein and daidzein. 相似文献
146.
《Journal of separation science》2018,41(15):3081-3088
An ionic‐liquid‐based in situ dispersive liquid–liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7–10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values. 相似文献
147.
Ho-Sang Shin 《Biomedical chromatography : BMC》2022,36(6):e5360
A method to determine 8 polychlorinated biphenyls (PCBs), 23 organochlorine pesticides (OCPs) and 16 polycyclic aromatic hydrocarbons (PAHs) was described using dispersive liquid–liquid microextraction (DLLME) of a small amount of plasma or serum sample and gas chromatography–tandem mass spectrometry (GC–MS/MS). The appropriate selection of the extraction solvent and dispersing solvent contributes to a high extraction yield and a clean extract. To verify the developed method, the interference, linearity of the calibration curve, detection limit, precision and accuracy were evaluated. The calibration curves were linear by 2–3 orders of magnitude with correlation coefficients above 0.997 in all cases. The LODs of PCBs, OCPs and PAHs were measured in the ranges of 0.0006–0.0029, 0.001–0.029 and 0.0002–0.012 ng/mL. The intraday precision achieved by this method was 2.19–10.3% (PCBs), 1.65–14.3% (OCPs) and 0.91–12.8% (PAHs), and the intraday accuracy 1.56–7.37% (PCBs), 2.34–19.6% (OCPs) and 1.49–15.7% (PAHs). The advantage of this method is that the analysis of PCBs, OCPs, and PAHs can be performed in a single chromatographic run, and the low detection limit enables monitoring of target substances in low exposure general public samples, and the analysis procedure is relatively simple and fast. 相似文献
148.
Emmanuel F. Olasehinde Ajibola V. Adegunloye Matthew A. Adebayo Aladesanmi A. Oshodi 《Analytical letters》2018,51(17):2708-2730
The efficacy of onion skins, both unmodified and chemically modified with thioglycolic acid, was investigated as alternative low-cost adsorbents for the sequestration of aqueous lead(II) ions from aqueous solution. The adsorbents were characterised using Fourier transform infrared spectroscopy and scanning electron microscopy – energy dispersive X-ray spectroscopy. Adsorption experiments were performed using batch sorption processes. The effects of contact time, pH, initial Pb(II) concentration, adsorbent dose, and temperature were investigated. Optimum sorption conditions were found at pH 4 and a 150?min equilibrium time for the modified onion skin and unmodified onion skin. The Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models were used to characterize the equilibrium experimental results. The equilibrium process was best described by the Freundlich isotherm. The maximum adsorption capacities of 4.878 and 6.173?mg/g were obtained for modified and unmodified adsorbents, respectively, using the Langmuir model. Kinetic studies indicated that the sorption of Pb(II) ions followed a pseudo-second-order model. Thermodynamic parameters such as standard enthalpy change (ΔH°), entropy change (ΔS°), and free energy change (ΔG°) were evaluated from the sorption experimental measurements. The results showed that the sorption process of Pb(II) ions on unmodified and modified onion skins was feasible and exothermic under the conditions used in this study. The sorption process followed the mechanism of physisorption. 相似文献
149.
Bouchra Belhaj Abdallah Ahmed Landoulsi Abdelwaheb Chatti 《Journal of Saudi Chemical Society》2018,22(1):110-118
The instant biosynthesis of silver nanoparticles under static electromagnetic induction, its antibacterial activity and its post exposure monitoring were reported here. A mix of silver nitrate solution and Ruta chalepensis leaf extract was irradiated by a static electromagnetic field (SMF) of 200 mT. The characteristics and stability of the biosynthesized silver nanoparticles (Ag NPs) were determined. Compared to the non-irradiated exposure, the morphology and state of the obtained material change once the exposition to SMF is turned off. Shifting from 453 to 473 nm, the percentage of the needles shaped silver nanoparticles increased and continue to win and dominate the biomixture toward the spherical silver nanoparticles. TEM microscopy showed a wide range of silver materials designed in different nanoscale morphology and beyond where they undergo major changes affecting mainly the size, shape and form (dispersity) of nanosilver. 相似文献
150.
《Journal of separation science》2018,41(3):713-722
A modified quick, easy, cheap, effective, rugged, and safe method was established for simultaneous extraction and cleanup of multiple antibiotics in leafy vegetables, and ultra‐high performance liquid chromatography with tandem mass spectrometry was used for analysis. Antibiotics in leafy vegetables were extracted with citric acid/sodium citrate in mixed solvents consisting of acetonitrile/methanol (85:15, v/v) from 10 g of vegetables. Octadecylsilyl and graphitized carbon black were used as dispersant adsorbents. This method was able to effectively extract all of the target antibiotics from leafy vegetables. The average recoveries of 20 antibiotics ranged from 57 to 91%. The limits of detection were 0.33–2.92 μg/kg. The developed method subsequently demonstrated its selectivity, sensitivity, and reliability for detecting multiple antibiotics in 15 samples. Antibiotic residues in vegetables have attracted great concern with respect to human health. It is recommended that standards should be established for antibiotic residues in vegetables to ensure food safety. 相似文献