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81.
Facile preparation of boronic acid‐functionalized magnetic nanoparticles with a high capacity and their use in the enrichment of cis‐diol‐containing compounds from plasma 下载免费PDF全文
Jin Du Maofang He Xiaomeng Wang Hua Fan Yinmao Wei 《Biomedical chromatography : BMC》2015,29(2):312-320
The use of bronate affinity adsorbents is a new separation method that appeared recently with great potential for specific extraction of cis‐diol‐containing compounds. In this work,a new strategy for the facile construction of boronic acid‐functionalized Fe3O4 magnetic nanoparticles (Fe3O4@FPBA MNPs) with a high capacity was described. The extraction capacity of the Fe3O4@FPBA MNPs was determined to be 66.0 ± 2.7 µmol/g for catechol and 80.6 ± 2.0 µmol/g for dopamine, being higher than that for the reported methods. The Fe3O4@FPBA MNPs were used to extract four cis‐diol drugs: caffeic acid isopropyl ester, caffic acid bornyl ester, isopropyl 3‐(3,4‐dihydroxyphenyl)‐2‐hydroxypropanoate and 3‐(3, 4‐dihydroxyphenyl)‐2‐hydroxylpropionic acid – from the spiked rabbit plasma, and the recoveries of four drugs were between 87.29 and104.37% with relative standard deviations ranging from 1.34 to 8.81%. Under the most favorable conditions, the solid‐phase extraction combined with HPLC‐UV for the analysis of four drugs in plasma could eliminate interferences from endogenous components of the biological fluids and exhibited sufficient precision and accuracy. These results showed that the prepared Fe3O4@FPBA MNPs were qualified for efficiently enriching and determining the trace cis‐diol substances from biological samples. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
82.
Simultaneous quantitative determination of 20 active components in the traditional Chinese medicine formula Zhi‐Zi‐Da‐Huang decoction by liquid chromatography coupled with mass spectrometry: application to study the chemical composition variations in different combinations 下载免费PDF全文
Zheng Tang Ran Yin Kaishun Bi Heyun Zhu Fei Han Kelin Chen Fenrong Wang 《Biomedical chromatography : BMC》2015,29(9):1406-1414
83.
A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air‐assisted liquid–liquid microextraction from human urine and plasma samples followed by gas chromatography–nitrogen phosphorous detection 下载免费PDF全文
Mir Ali Farajzadeh Mohammad Reza Afshar Mogaddam Ali Akbar Alizadeh Nabil 《Biomedical chromatography : BMC》2015,29(12):1921-1931
In present study, a simultaneous derivatization and air‐assisted liquid–liquid microextraction method combined with gas chromatography–nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1‐flouro‐2,4‐dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05–0.34 ng mL?1 are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
84.
D3h‐Symmetric Porphyrin‐Based Rigid Macrocyclic Ligands for Multicofacial Multinuclear Complexes in a One‐Nanometer‐Sized Cavity 下载免费PDF全文
Yohei Ohkoda Akane Asaishi Tomoya Namiki Tomoaki Hashimoto Midori Yamada Koichiro Shirai Yuta Katagami Dr. Tomoaki Sugaya Prof. Makoto Tadokoro Prof. Akiharu Satake 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(33):11745-11756
The one‐step synthesis of D3h‐symmetric cyclic porphyrin trimers 1 composed of three 2,2′‐[4,4′‐bis(methoxycarbonyl)]bipyridyl moieties and three porphyrinatozinc moieties was achieved from a nickel‐mediated reductive coupling of meso‐5,15‐bis(6‐chloro‐4‐methoxycarbonylpyrid‐2‐yl)porphyrinatozinc. Although cyclic trimers 1 were obtained as a mixture that included other cyclic and acyclic porphyrin oligomers, an extremely specific separation was observed only for cyclic trimers 1 when using columns of silica gel modified with pyrenylethyl, cyanopropyl, and other groups. Structural analysis of cyclic trimers 1 was carried out by means of NMR spectroscopy and X‐ray crystallography. Treatment of an η3‐allylpalladium complex with a cyclic trimer gave a tris(palladium) complex containing three η3‐allylpalladium groups inside the space, which indicated that the bipyridyl moieties inside the ring could work as bidentate metalloligands. 相似文献
85.
Jigneshkumar P. Patel Zou Guo Xiang Shaw Ling Hsu Andrew B. Schoch Sena Ada Carleen Dean Matsumoto 《Journal of Polymer Science.Polymer Physics》2015,53(21):1519-1526
A uniform dispersion of reactants is necessary to achieve a complete reaction involving multicomponents. In this study, we have examined the role of plasticizer in the reaction of two seemingly unlikely reactants: a highly crystalline hexamethylenetetramine (HMTA) and a strongly hydrogen bonded phenol formaldehyde resin. By combining information from NMR, infrared spectroscopy and differential scanning calorimetry, we were able to determine the role of specific intermolecular interactions necessary for the plasticizer to dissolve the highly crystalline HMTA and to plasticize the phenol formaldehyde resin in this crosslinking reaction. The presence of the plasticizer increased the segmental mobility, disrupted the hydrogen bonded matrix, and freed the hydroxyl units, which further increased the solubility of the HMTA. Both the endothermic and exothermic transitions are accounted for in the calorimetric data obtained. For the first time, it is possible to obtain the effective molar ratio of each component needed to complete the crosslinking reaction efficiently. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1519–1526 相似文献
86.
Facile LC‐UV methods for simultaneous monitoring of ciprofloxacin and rosuvastatin in API,formulations and human serum 下载免费PDF全文
An efficient, selective and cost‐effective liquid chromatographic assay was developed and validated for the simultaneous quantification of ciprofloxacin and rosuvastatin in Active Pharmaceutical Ingredients (API), pharmaceutical formulations and in human serum. The chromatographic system consisted of mobile phase methanol–water, 90:10 v/v at pH 3.0 adjusted with o‐phosphoric acid, pumped at 1.0 mL/min through a prepacked Purospher Star C18 (5 µm, 25 × 0.46 cm) column and effluent was monitored at the isosbestic point (255 nm) as well as at the λmax of individual drugs (243 and 271 nm). The method was validated over a linear concentration range of 0.25–15 µg/mL for ciprofloxacin and 0.33–20 µg/mL for rosuvastatin (r2 ≥ 0.999). The ranges of reliable response (limits of detection and quantitation) for ciprofloxacin were 3–15 and 9–45 ng/mL and 17–29 and 52–88 ng/mL, respectively, for rosuvastatin in all API, pharmaceutical formulations and human serum. Analytical recovery from human serum was >98% and relative standard deviation (RSD) was <2. The accuracies were 97.13–102.55 and 97.41–101.31% and precisions in RSD were 0.04–1.90 and 0.02–1.23% for ciprofloxacin and rosuvastatin, respectively. No matrix interferences, ion suppression/enhancement and carry‐over were detected. The total assay run time was less than 5 min. In another study, for optimum performance the detector was programmed for multiwavelength scanning at the absorption maxima of each component. Consequently, the linearity range was improved and limit of detection and quantitation values were down to 1–4 and 4–12 ng/mL for ciprofloxacin and 3–5 and 9–15 ng/mL for rosuvastatin, respectively. The validation parameters fitted ICH guidelines through the isosbestic and individual λmax approach. The small sample volume and simplicity of preparation make this method suitable for use in human serum samples, pharmaceutical formulations, quality control, drug–drug interaction studies, clinical laboratories, drug research centers and forensic medical centers. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
87.
Design and development of a two‐dimensional system based on hydrophilic and reversed‐phase liquid chromatography with on‐line sample treatment for the simultaneous separation of excreted xenobiotics and endogenous metabolites in urine 下载免费PDF全文
Diego García‐Gómez Encarnación Rodríguez‐Gonzalo Rita Carabias‐Martínez 《Biomedical chromatography : BMC》2015,29(8):1190-1196
In the present work we describe a two‐dimensional liquid chromatographic system (2D‐LC) with detection by mass spectrometry (MS) for the simultaneous separation of endogenous metabolites of clinical interest and excreted xenobiotics deriving from exposure to toxic compounds. The 2D‐LC system involves two orthogonal chromatographic modes, hydrophilic interaction liquid chromatography (HILIC) to separate polar endogenous metabolites and reversed‐phase (RP) chromatography to separate excreted xenobiotics of low and intermediate polarity. Additionally, the present proposal has the novelty of incorporating an on‐line sample treatment based on the use of restricted access materials (RAMs), which permits the direct injection of urine samples into the system. The work is focused on the instrumental coupling, studying all possible options and attempting to circumvent the problems of solvent incompatibility between the RAM device and the two chromatographic columns, HILIC and RP. The instrumental configuration developed, RAM‐HILIC‐RPLC‐MS/MS, allows the simultaneous assessment of urinary metabolites of clinical interest and excreted compounds derived from exposure to toxic agents with minimal sample manipulation. Thus, it may be of interest in areas such as occupational and environmental toxicology in order to explore the possible relationship between the two types of compounds. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
88.
Resolution and isolation of enantiomers of (±)‐isoxsuprine using thin silica gel layers impregnated with l‐glutamic acid,comparison of separation of its diastereomers prepared with chiral derivatizing reagents having l‐amino acids as chiral auxiliaries 下载免费PDF全文
Thin silica gel layers impregnated with optically pure l ‐glutamic acid were used for direct resolution of enantiomers of (±)‐isoxsuprine in their native form. Three chiral derivatizing reagents, based on DFDNB moiety, were synthesized having l ‐alanine, l ‐valine and S‐benzyl‐l ‐cysteine as chiral auxiliaries. These were used to prepare diastereomers under microwave irradiation and conventional heating. The diastereomers were separated by reversed‐phase high‐performance liquid chromatography on a C18 column with detection at 340 nm using gradient elution with mobile phase containing aqueous trifluoroacetic acid and acetonitrile in different compositions and by thin‐layer chromatography (TLC) on reversed phase (RP) C18 plates. Diastereomers prepared with enantiomerically pure (+)‐isoxsuprine were used as standards for the determination of the elution order of diastereomers of (±)‐isoxsuprine. The elution order in the experimental study of RP‐TLC and RP‐HPLC supported the developed optimized structures of diastereomers based on density functional theory. The limit of detection was 0.1–0.09 µg/mL in TLC while it was in the range of 22–23 pg/mL in HPLC and 11–13 ng/mL in RP‐TLC for each enantiomer. The conditions of derivatization and chromatographic separation were optimized. The method was validated for accuracy, precision, limit of detection and limit of quantification. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
89.
A rapid and effective preparative procedure has been evaluated for the accurate determination of low-energy (40–200 keV) gamma-emitting radionuclides (210Pb, 234Th, 226Ra, 235U) in uranium ores and uranium ore concentrates (UOCs) using high-resolution gamma ray spectrometry. The measurement of low-energy gamma photons is complicated in heterogeneous samples containing high-density mineral phases and in such situations activity concentrations will be underestimated. This is because attenuation corrections, calculated based on sample mean density, do not properly correct where dense grains are dispersed within a less dense matrix (analogous to a nugget effect). The current method overcomes these problems using a lithium tetraborate fusion that readily dissolves all components including high-density, self-attenuating minerals/compounds. This is the ideal method for dissolving complex, non-volatile components in soils, rocks, mineral concentrates, and other materials where density reduction is required. Lithium borate fusion avoids the need for theoretical efficiency corrections or measurement of matrix matched calibration standards. The resulting homogeneous quenched glass produced can be quickly dissolved in nitric acid producing low-density solutions that can be counted by gamma spectrometry. The effectiveness of the technique is demonstrated using uranium-bearing Certified Reference Materials and provides accurate activity concentration determinations compared to the underestimated activity concentrations derived from direct measurements of a bulk sample. The procedure offers an effective solution for initial nuclear forensic studies where complex refractory minerals or matrices exist. It is also significantly faster, safer and simpler than alternative approaches. 相似文献
90.
Profiling engineered data with robust mining methods continues attracting attention in knowledge engineering systems. The purpose of this article is to propose a simple technique that deals with non-linear multi-factorial multi-characteristic screening suitable for knowledge discovery studies. The method is designed to proactively seek and quantify significant information content in engineered mini-datasets. This is achieved by deploying replicated fractional-factorial sampling schemes. Compiled multi-response data are converted to a single master-response effectuated by a series of distribution-free transformations and multi-compressed data fusions. The resulting amalgamated master response is deciphered by non-linear multi-factorial stealth stochastics intended for saturated schemes. The stealth properties of our method target processing datasets which might be overwhelmed by a lack of knowledge about the nature of reference distributions at play. Stealth features are triggered to overcome restrictions regarding the data normality conformance, the effect sparsity assumption and the inherent collapse of the ‘unexplainable error’ connotation in saturated arrays. The technique is showcased by profiling four ordinary controlling factors that influence webpage content performance by collecting data from a commercial browser monitoring service on a large scale web host. The examined effects are: (1) the number of Cascading Style Sheets files, (2) the number of JavaScript files, (3) the number of Image files, and (4) the Domain Name System Aliasing. The webpage performance level was screened against three popular characteristics: (1) the time to first visual, (2) the total loading time, and (3) the customer satisfaction. Our robust multi-response data mining technique is elucidated for a ten-replicate run study dictated by an L9(34) orthogonal array scheme where any uncontrolled noise embedded contribution has not been necessarily excluded. 相似文献