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JPC – Journal of Planar Chromatography – Modern TLC - A new bonded RP-18 sintered silica gel plate for use in reversed-phase planar electrochromatography has been prepared in our... 相似文献
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A set of numerical experiments has been conducted to study the effect of a precursor fluid layer on the motion of two phase system in a channel. This system is characterized by coupled Cahn-Hillard and Navier-Stokes system together with slip boundary conditions. The solution of the governing equation involves first the solution of Cahn-Hillard equation with semi-implicit and Mixed finite element discritization with a convex splitting scheme. The Navier-Stokes equations are then solved with a P2-P0 mixed finite element method. Three cases have been investigated; in the first the effect of different wettability scenarios with no precursor layer has been investigated. In the second scenario, the effect of the precursor layer for different wettability conditions is investigated. In the third case, the effect of the thickness of the precursor layer is investigated. It is found that, wettability conditions have considerable effect on the flow of the considered two-phase system. Furthermore the existence of the precursor layer has additional influence on the breakthrough of the phases. 相似文献
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In this study, a porous polypropylene frit was coated with polydimethylsiloxane (PDMS) as extraction medium, based on the home-made PDMS-frit, a rapid, simple and sensitive sorptive extraction method was established for analysis of potential biomarkers of lung cancer (hexanal and heptanal) in human serum samples. In the method, derivatization and extraction occurred simultaneously on the PDMS-frit, then the loaded frit was ultrasonically desorbed in acetonitrile. Polymerization, derivatization–extraction and desorption conditions were optimized. Under the optimal conditions, satisfactory results were gained, a wide linear application range was obtained in the range of 0.002–5.0 μmol L−1 (R > 0.997) for two aldehydes, the detection limits (S N−1 = 3) were 0.5 nmol L−1 for hexanal and 0.4 nmol L−1 for heptanal. The relative standard deviations (RSDs, n = 5) of the method were below 7.9% and the recoveries were above 72.7% for the spiked serum. All these results hint that the proposed method is potential for disease markers analysis in complex biological samples. 相似文献
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Xiaojia Huang Linli Chen Meng Chen Dongxing Yuan Shuyu Nong 《Journal of separation science》2013,36(5):907-915
In the present study, a convenient and sensitive method for determination of six penicillin antibiotics (amoxicillin, ampicillin, penicillin G, oxacillin, cloxacillin, and dicloxacillin) in milk and honey samples was developed. Milk and honey samples were diluted with water, then directly treated by stir bar sorptive extraction based on poly (vinylimidazole‐divinylbenzene) monolithic material as coating. The analytes were analyzed by LC/ESI‐ MS/MS. Several extraction parameters including extraction and desorption time, pH value, and ionic strength in sample matrix were investigated in detail. Under the optimized extraction conditions, the calculated detection limits for the target compounds were as low as 0.23–2.66 ng/kg in milk and 0.18–1.42 ng/kg in honey, respectively. Good linearity was obtained for analytes with the correlation coefficients (R2) above 0.997. Excellent method reproducibility was achieved in terms of intraday and interday precisions, indicated by the RSDs of <5.0 and <10.0%, respectively. Finally, the proposed method was successfully applied to the determination of penicillin antibiotics residues in different milk and honey samples. 相似文献
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Xiaojia Huang Yulei Wang Dongxing Yuan Xiaojing Li Shuyu Nong 《Analytical and bioanalytical chemistry》2013,405(7):2185-2193
A novel porous monolith has been prepared and used as a sorbent in stir-cake-sorptive extraction (SCSE). The monolithic material was prepared by in-situ copolymerization of allyl thiourea (AT) and divinylbenzene (DB) in the presence of dimethylformamide as a porogen solvent. To optimize the polymerization conditions, different monoliths with different ratios of functional monomer to porogenic solvent were prepared, and their extraction efficiency was investigated in detail. The monolith was characterized by elemental analysis, scanning electron microscopy, mercury intrusion porosimetry, and infrared spectroscopy. Analysis of polar phenols in environmental water samples by a combination of ATDB-SCSE and HPLC with diode-array detection was selected as a model for the practical application of the new sorbent. Several extraction conditions, including extraction and desorption time, pH, and ionic strength of the sample matrix were optimized. The results showed that the new monolith had high affinity for polar phenols and could be used to extract them effectively. Under the optimum conditions, low detection (S/N?=?3) and quantification (S/N?=?10) limits were achieved for the phenols, within the ranges 0.18–0.90 and 0.59–2.97 μg L?1, respectively. The linearity of the method was good, and the method enabled simple, practical, and low-cost extraction of these analytes. The distribution coefficients between ATDB and water (K ATDB/W) were calculated for the phenolic compounds and compared with K O/W. Finally, the proposed method was successfully applied to the determination of the compounds in three environmental water samples, with acceptable recovery and satisfactory repeatability. Figure
HPLC chromatograms of real water sample treated with ATDB-SCSE (a) and spiked water sample treated with ATDB-SCSE (b) 相似文献
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Jilong Li Yanhui Wang Rushuo Li Bowen Lu Yungang Yuan Hongwei Gao Shiwei Song Shuyu Zhou Jianbing Zang 《Electroanalysis》2021,33(10):2252-2259
A self-modified film electrode consisting of homogeneous snowflake-shaped nanoparticles on the amorphous carbon substrate (HNAC) was prepared by low temperature carbonization of phenolic resin. Such a unique structure was beneficial to enhance the electroanalysis signal responds. Simultaneous detection of DA and UA was performed on the HNAC using differential pulse voltammetry (DPV) at pH 8 phosphate buffer. The well-defined oxidation peak potential separation reached 260 mV between DA and UA. Meanwhile, the detection limit of HNAC were 0.401 μM (DA) and 2.800 μM (UA). 相似文献