Home About us Contact
|
Home About us Contact | ||
|
|
||
Elution Volume (elution + volume)
Selected AbstractsMagnesium oxide microspheres as a novel solid-phase extraction sorbent for the determination of benzo[a]pyrene in environmental water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2010Jing Jin Abstract Magnesium oxide microspheres were developed as a novel SPE sorbent for the determination of benzo[a]pyrene (BaP), one of the most potent carcinogenic agents, in environmental water samples. The parameters controlling the extraction efficiency, such as elution volume, flow rate, pH values, and breakthrough volume, were investigated in detail. Considering the facile preparation and satisfying recovery, a corresponding analytical method has been developed to determine the concentration of BaP in real tap water, river water, and seawater. The recoveries for the spiked BaP were excellent (94,101%). [source] Hexafluoroisopropanol as size exclusion chromatography mobile phase for Polyamide 6JOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2004Raniero Mendichi Abstract The present study deals with the use of hexafluoroisopropanol (HFIP) as size exclusion chromatography (SEC) mobile phase for polyamide 6 (PA6). Contradictory conclusions relating to the use of HFIP as SEC mobile phase for polyamides are found in the literature. By using a multi-detector SEC apparatus equipped with on-line viscometer and multi-angle light scattering we have studied the chromatographic artifacts and the validity of the universal calibration (UC) in HFIP for different PA6 samples (hydrolytic and anionic, monofunctional or bifunctional activator). Appropriate SEC columns and optimized experimental conditions allow most of the chromatographic artifacts to be avoided, even in neat HFIP. The use of a salt in the mobile phase, namely 0.01 M tetraethylammonium nitrate (TEAN), slightly increases the elution volume for both PA6 and PMMA polymers. Under the right conditions, the UC substantially holds for PA6. The validity of the UC is not linked to the presence of TEAN in the mobile phase. With some PA6 samples, namely those anionically synthesized using a bifunctional activator, aggregation becomes a problem and the molar mass in neat HFIP is overestimated. Addition of TEAN prevents any aggregation of the above anionically synthesized PA6. In contrast, the use of a different salt, namely potassium trifluoroacetate, increases the extent of aggregation. [source] Semi-online nanoflow liquid chromatography/matrix-assisted laser desorption ionization mass spectrometry of synthetic polymers using an octadecylsilyl-modified monolithic silica capillary columnRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2010Takehiro Watanabe We have designed a semi-online liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (LC/MALDI-MS) system to introduce eluent from a octadecylsilyl (ODS) group modified monolithic silica capillary chromatographic column directly onto a sample plate for MALDI-MS analysis. Our novel semi-online system is useful for rapidly and sensitively examining the performance of a monolithic capillary column. An additional advantage is the small elution volume of a monolithic capillary column, which allows delicate eluents, such as 1,1,1,3,3,3,-hexafluoroisopropyl alcohol (HFIP), to be used to achieve cost-effective analysis. Using the semi-online LC/MALDI-MS system, chromatographic separation of polymers by the monolithic column with different eluents was studied. Separation of poly(methyl methacrylate) and Nylon 6/6 showed that the column functioned via size-exclusion separation when tetrahydrofuran or HFIP eluent was used. On the other hand, the separation behavior of Nylon 11 indicated a reversed-phase mode owing to the interaction of the polymer with the modified ODS group in the column. Using tetrahydrofuran/methanol (1:1, v/v) as the eluent, the LC/MALDI-MS spectra of poly(lactic acid), which contains both linear and cyclic polymer structures, showed that the column could separate the hydrophobic cyclic polymer and elute it out relatively slowly. The monolithic column functions basically via size-exclusion separation; the reversed-phase separation by interaction with the ODS functions may have less influence on column separation. The semi-online monolithic capillary LC/MALDI-MS method we have developed should provide a means of effectively analyzing synthetic polymers. Copyright © 2010 John Wiley & Sons, Ltd. [source] Molted feathers from clay licks in Peru provide DNA for three large macaws (Ara ararauna, A. chloropterus, and A. macao)JOURNAL OF FIELD ORNITHOLOGY, Issue 2 2009Kara J. Gebhardt ABSTRACT Conservation genetic analyses of wildlife have increased greatly in the past 10 yr, yet genetic studies of parrots are rare because of difficulties associated with capturing them and obtaining samples. Recent studies have demonstrated that molted feathers can provide a useful source of DNA, but success rates have varied considerably among studies. Our objective was to determine if molted macaw feathers from Blue-and-yellow Macaws (Ara ararauna), Scarlet Macaws (A. macao), and Red-and-green Macaws (A. chloropterus) collected from rainforest geophagy sites called clay licks could provide a good source of DNA for population genetic studies. Specific objectives were to determine (1) how nuclear DNA microsatellite amplification success and genotyping error rates for plucked macaw feathers compared to those for molted feathers collected from clay licks in the Amazon rainforest, and (2) if feather size, feather condition, species, or extraction method affected microsatellite amplification success or genotyping error rates from molted feathers. Amplification success and error rates were calculated using duplicate analyses of four microsatellite loci. We found that plucked feathers were an excellent source of DNA, with significantly higher success rates (P < 0.0001) and lower error rates (P= 0.0002) than for molted feathers. However, relatively high success rates (75.6%) were obtained for molted feathers, with a genotyping error rate of 11.7%. For molted feathers, we had higher success rates and lower error rates for large feathers than small feathers and for feathers in good condition than feathers that were moldy and broken when collected. We also found that longer incubation times and lower elution volumes yielded the highest quality DNA when extracting with the Qiagen DNeasy tissue kit. Our study demonstrates that molted feathers can be a valuable source of genetic material even in the challenging conditions of tropical rainforests, and our results provide valuable information for maximizing DNA amplification success rates when working with shed feathers of parrots. SINOPSIS Los análisis genéticos para la conservación de la vida silvestre han crecido en gran escala durante los últimos 10 años, pero el análisis genético de los loros son raros por las dificultades asociados con su captura y obtención de muestras. Estudios recientes han demostrado que plumas mudadas podrían proveer una fuente útil de ADN, pero las tasas de éxito varían considerablemente entre estudios. Nuestro objetivo fue determinar si las plumas mudadas de Ara ararauna, A. macao y A. chloropterus colectadas en sitios de bosque húmedo donde estas aves consumen el suelo, llamados colpas, podrían proveer una fuente útil de ADN para estudios de la genética de las poblaciones. Los objetivos específicos fueron determinar (1) como comparan las tasas de éxito de la amplificación de los microsatélites del ADN nuclear y las tasas de error en el análisis del genotipo de plumas, entre plumas colectadas directamente de los guacamayos y plumas colectadas en colpas en el bosque Amazónico, y (2) si el tamaño de la pluma, su condición, la especie o el método de extracción afecta el éxito de la amplificación de los microsatélites o las tasas de error en el análisis del genotipo de las plumas mudadas. Las tasas de éxito de amplificación y error fueron calculados usando análisis duplicados de cuatro loci de microsatélites. Encontramos que plumas colectadas directamente de las aves son una fuente excelente de ADN, con tasas de éxito significativamente más altas (P < 0.0001), y con menores tasas de error (P= 0.0002) que las plumas mudadas. Sin embargo, tasas de éxito relativamente altas (75.6%) fueron obtenidos de plumas mudadas, con una tasa de error en el análisis del genotipo de 11.7%. Para plumas mudadas, tuvimos tasas de éxito más altas y tasas de error menores para plumas grandes que para plumas pequeñas y para plumas en buena condición que para plumas que estaban cubiertos con hongos y quebradas cuando fueron colectadas. También encontramos que mayores periodos de incubación y menores volúmenes de elución proveían el ADN de mayor calidad cuando se extraía el ADN usando el kit de tejido Quiagen DNeasy. Nuestro estudio demuestra que las plumas mudadas pueden ser una fuente valiosa de materia genética, hasta en las condiciones de los bosques húmedos tropicales. Nuestros resultados proveen información valiosa para maximizar las tasas de éxito de la amplificación del ADN cuando se analizan las plumas mudadas de los loros. [source] Surface interaction of well-defined, concentrated poly(2-hydroxyethyl methacrylate) brushes with proteinsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2007Chiaki Yoshikawa Abstract The interaction of concentrated polymer brushes with proteins was chromatographically investigated. By the use of surface-initiated atom transfer radical polymerization, a low-polydispersity poly(2-hydroxyethyl methacrylate) (PHEMA) was densely grafted onto the inner surfaces of silica monoliths with mesopores of about 50 and 80 nm in mean size. The graft density reached 0.4,0.5 chains/nm2. The 80-nm-mesopore monolithic column with the concentrated PHEMA brush was characterized through the elution of low-polydispersity pullulans with different molecular weights, clearly showing two modes of size exclusion, that is, one by the mesopores and the other by the brush phase. The latter mode gave a sharp separation with a critical molecular weight (size-exclusion limit) of about 1000. This molecular size of pullulan was comparable to the distance between the nearest-neighbor graft points. The elution behaviors of five proteins of different sizes (bovine serum thyroglobulin, bovine serum immunoglobulin G, bovine serum albumin, horse heart myoglobin, and bovine serum aprotinin) were studied with this PHEMA-grafted column. The smallest protein, aprotinin, with a pullulan-reduced molecular weight slightly larger than the critical value of 1000, was eluted much behind the corresponding pullulan, and this indicated that it barely got into the brush layer, suffering from a strong affinity interaction within the brush. On the other hand, the other four larger proteins were eluted at the same elution volumes as the equivalent pullulans, and this meant that they were perfectly excluded from the brush layer and separated only in the size-exclusion mode by the mesopores without an affinity interaction with the brush surface. This excellent inertness of the concentrated brush in the interaction with the large proteins should afford the system long-term stability against biofouling. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4795,4803, 2007 [source] | ||||||||||