共查询到8条相似文献,搜索用时 0 毫秒
1.
Vapor–liquid equilibria (VLE) data at 100 kPa have been determinated for the ternary system cyclohexane + cyclohexene + morpholine and two constituent binary systems cyclohexane + morpholine and cyclohexene + morpholine. The thermodynamic consistency of experimental data has been verified. Both binary systems deviate moderately from ideality without the presence of an azeotrope. The VLE data have been well correlated using local composition models (Wilson, NRTL and UNIQUAC) and have been also predicted with the original UNIFAC. 相似文献
2.
Mohammad Rezaee Yadollah Yamini Shahab Shariati Ali Esrafili Mojtaba Shamsipur 《Journal of chromatography. A》2009,1216(9):1511-1514
Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC)-UV detection was applied for the extraction and determination of bisphenol A (BPA) in water samples. An appropriate mixture of acetone (disperser solvent) and chloroform (extraction solvent) was injected rapidly into a water sample containing BPA. After extraction, sedimented phase was analyzed by HPLC-UV. Under the optimum conditions (extractant solvent: 142 μL of chloroform, disperser solvent: 2.0 mL of acetone, and without salt addition), the calibration graph was linear in the range of 0.5–100 μg L−1 with the detection limit of 0.07 μg L−1 for BPA. The relative standard deviation (RSD, n = 5) for the extraction and determination of 100 μg L−1 of BPA in the aqueous samples was 6.0%. The results showed that DLLME is a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of BPA in water samples and suitable results were obtained. 相似文献
3.
Marzieh Sadeghi Fatemeh Shiri Davood Kordestani Pourya Mohammadi Abodolhamid Alizadeh 《Journal of the Iranian Chemical Society》2018,15(4):753-768
This paper established a new, rapid and sensitive method for the ultra-trace determination of lead, cadmium and nickel in food and environmental samples preconcentrated by dispersive solid-phase extraction (DSPE) combined with surfactant-assisted dispersive liquid–liquid microextraction (SA-DLLME) prior to graphite furnace atomic absorption spectrometry. SBA-15/Met was synthesized and used as a new efficient sorbent for the extraction of metal ions in DSPE. It was characterized by TEM and TGA techniques. After DSPE step, stripped metal elements were complexed with dithizone, and then, the complexes were extracted into carbon tetrachloride by using SA-DLLME. A conventional nonionic surfactant, triton X-100 was used as a disperser agent. Under the optimized conditions, the limit of quantifications was found to be 2.5 ng L?1 for Pb2+, Cd2+ and 5.0 ng L?1 for Ni2+. The limits of detection were 1.5 ng L?1 for Ni2+ and 0.75 ng L?1 for Pb2+ and Cd2+, with enrichment factor of 1650. The optimized method exhibited a good precision level with relative standard deviations (RSDs%) values of 4.9, 5.2 and 5.0% for 1 μg L?1 Pb2+, Cd2+ and Ni2+, respectively (n = 7). Application of the proposed method to the analysis of fish-certified reference material produced results that were in good agreement with the certified values. 相似文献
4.
Yanbin Lu Qing Shen Zhiyuan Dai Hong Zhang 《Analytical and bioanalytical chemistry》2010,398(4):1819-1826
In the present work, a high-performance liquid chromatography–tandem mass spectrometry method has been developed for the residue
analysis of chloramphenicol (CAP) in several food matrices. Following the addition of D5-CAP as internal standard, egg, honey, and milk were extracted and cleaned by means of solid-phase extraction, utilizing multi-walled
carbon nanotubes as sorbent. The extracts were separated on a Halo fused-core C18 column (50 mm × 2.1 mm, 2.7 μm) and quantified
by a 4000 Q-trap mass spectrometer equipped with a TurboIonSpray™ interface using electrospray ionization and multiple-reaction
monitoring mode. The method validation was performed according to the criteria of Commission Decision 2002/657/EC. The decision
limit (CCα) and detection capability (CCβ) of CAP in milk were calculated for m/z 320.8 > 151.9. Due to the existence of slight signal suppression, quantification was performed by matrix-matched calibration
curves, ranging from 0.1 to 100 ng mL−1, with regression coefficients of 0.9993, 0.9998, and 0.9997 for egg, honey, and milk, respectively. Mean recoveries of the
CAP ranged from 95.8% to 102.3%, with the corresponding intra- and inter-day variation (relative standard deviation) less
than 7.13% and 8.89%, respectively. The limit of detection and limit of quantification of the method were also reported. This
method successfully applied to several food matrixes (egg, honey, and milk) and can serve as a monitoring tool to avoid unacceptable
levels of residues of CAP entering the food chain. 相似文献
5.
6.
《Fluid Phase Equilibria》2004,218(1):69-76
Reliable P–x and enthalpy of mixing data have been measured for the ternary systems 1-hexene+water+N-methyl-2-pyrrolidone (NMP), 3-methylcyclopentene+water+NMP, 3-methylpentane+water+NMP, 1-pentene+water+NMP, and 2-methylbutane+water+NMP at 90 °C, and for 1-hexene+water+NMP also at 140 °C using a static apparatus and an isothermal flow calorimeter, respectively. Activity coefficients at infinite dilution for the different hydrocarbons in the solvent have been derived from the P–x data in the dilute composition range, where the water content of NMP ranged between 0 and 6 wt.%. NRTL parameters have been fitted to the experimental data. 相似文献
7.
Farzaneh Dehghani Ali Reza Sardarian Mohammad Mehdi Doroodmand 《Journal of the Iranian Chemical Society》2014,11(3):673-684
A novel, efficient, heterogeneous, and reusable multi-walled carbon nanotubes (MWCNTs), functionalized with phosphonic acid (MWCNTs–C–PO3H2) has been synthesized. The synthesized CNTs were characterized using some electron microscopic techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Energy dispersive X-ray spectroscopy (EDAX), and also some thermal and spectroscopic methods such as thermogravimetry (TG). The nitrogen adsorption behavior of the MWCNTs–C–PO3H2 catalyst was evaluated using the TG instrumentation system at 25 °C. The catalyst was applied successfully for highly efficient and selective acetylation of alcohols, phenols, thiols and aromatic amines with acetic anhydride at room temperature under solvent-free conditions. The reusability of the catalyst was checked and the recovered catalyst was reused for five runs without significant loss in activity. 相似文献
8.
Wei-Kuan Chen Kun-Jung Lee Chieh-Ming J. Chang Jing-Wei Ko Liang-Sun Lee 《Fluid Phase Equilibria》2010
Isothermal vapor–liquid equilibria at 333.15 K, 343.15 K and 353.15 K for three binary mixtures of o-xylene, m-xylene and p-xylene individually mixed with N-methylformamide (NMF), have been obtained at pressures ranged from 0 kPa to 101.3 kPa over the whole composition range. The Wilson, NRTL and UNIQUAC activity coefficient models have been employed to correlate experimental pressures and liquid mole fractions. The non-ideal behavior of the vapor phase has been considered by using the Peng–Robinson equation of state in calculating the vapor mole fraction. Liquid and vapor densities were measured by using two vibrating tube densitometers. The excess molar volumes of the liquid phase were also determined. Three systems of o-xylene + NMF, m-xylene + NMF and p-xylene + NMF mixtures present large positive deviations from the ideal solution and belong to endothermic mixings because their excess Gibbs energies are positive. Temperature dependent intermolecular parameters in the NRTL model correlation were finally obtained in this study. 相似文献