Novel polymer-coated fiber-packed microcolumns in liquid chromatography (LC) have been developed. Typical polymeric materials, such as polydimethylsiloxane and polyethyleneglycol, which are conventional stationary phases of capillary columns in gas chromatography (GC), have been employed as coating materials onto the surface of fine filaments. Packed longitudinally with a bundle of polymer-coated filaments into a stainless-steel capillary of 0.8 mm i.d., 150 mm length, several types of polymer-coated fiber-packed columns were prepared, and the retention behavior of aromatic compounds on these columns has been studied. A good linear relationship was obtained for van't Hoff plots over the temperature range between 0 and 200 C, clearly indicating an excellent heat-resistant property of these polymer-coated fibrous stationary phases. Taking advantage of the heat-resistant feature of the fibrous stationary phases, the separation of several test mixtures with temperature-programmed elution was studied, where a solvent gradient program was additionally introduced if needed. Separation was also carried out with pure water as the mobile phase using an appropriate temperature program.
Preconcentration of aqueous solution of aromatic compounds was successfully carried out with an extraction capillary packed with a bundle of polymer-coated filaments. The extracted analytes were sequentially eluted with a flow of pure water using programmed temperature elevation of the extraction capillary. The results clearly suggest that the polymer-coated fiber-packed capillary could be employed as a sample preparation medium for the analysis of aqueous matrices. The fraction of interest could be transferred to conventional microcolumn liquid chromatography (LC) allowing a heart cutting analysis of aqueous matrices. Stability of the fiber-packed capillary was confirmed with pure water as the mobile phase at elevated temperatures.
IntroductionHigh performance liquid chromatography (HPLC) is one of the most important technologies in separation science in fields including agricultural, pharmaceutical, and medical science [1]. In particular, a significant degree of the performance of LC systems is due to columns which can separate complex mixtures, and columns are constantly being improved to obtain optimal separations of an enormous variety of samples. The most popular columns for HPLC are packed columns containing silica packings with octadecyl groups, called octadecylsilica (ODS) columns. The ODS column is appropriate for separations of a wide range of samples, and can be used for the rapid separations under high pressure conditions due to the good toughness of silica packings. Silica-gel particles with smaller sizes have also been developed to obtain the higher column efficiencies, high-sensitivity, and high-throughput analyses [2][3][4]. In order to use smaller particles, however, LC pumps need to have high levels of performance to flow mobile phases at higher pressures, due to increased column back pressures.Furthermore, it may somewhat difficult for silica-gel particles to separate samples under excessive basic conditions, due to decreases in theoretical plate numbers and tailing of sample peaks possibly induced by the hydrolysis of silica-surfaces in columns. Hence, silica-based columns might not be appropriate for separations of basic compounds in some cases. For a similar reason, structures composed of silica are not appropriate when using mobile phases consisting of only water alone.In contrast to these columns, packed columns with fibrous stationary phases have been developed. These fibers are aligned parallel in the column. This arrangement of fiber bundles makes it possible to flow mobile phases at low back pressures. AbstractSurface derivatization of poly(p-phenylene terephthalamide) (PPTA) fibers was studied to prepare novel stationary phases in liquid chromatography (LC). As one type of surface derivatization of synthetic fibers, alkyl or perfluoroalkyl chains as functional groups were introduced to the surfaces of PPTA fibers. When each functionalized fiber-packed column was used for LC, increases in retention power with respect to a variety of compounds were ascertained in comparison with that prepared by an untreated-fiber as the stationary phase. Furthermore, it was indicated that the perfluoroalkyl group introduced fibrous stationary phase showed a specific retention behavior with respect to halogenated benzenes. These results demonstrated that the derivatization of the surfaces of PPTA fibers was successfully carried out. Selectivity differences between the modified-fiber packed columns were also confirmed through the use of some sample probes.
This article discusses the present state of access to books and other reading materials for inmates in Japan's correctional facilities. While no professionally managed libraries are provided at these facilitieswhich explains why the term Prison Libraries in the title of this article is placed in quotation marks-incarcerated persons have the opportunity to obtain personal books, magazines, and newspapers through purchase or gifts. The prison administration also provides a certain number of reading materials at various locations within the institution. These materials, however, are inadequate and do not meet the needs of the offenders. The author discusses the legal framework that specifies the right of prisoners to read and obtain information, as well as the limits imposed on this access. The article contains information obtained by the author from a recent survey of seven correctional facilities. The author includes recommendations made by various advocacy groups, including the Japan Federation of Bar Associations, for improvement of the "prison library" situation and concludes with several of his own proposals to establish professionally operated prison libraries, to develop better collections, and to enhance cooperation between correctional facilities and public libraries.
A bundle of polymer-coated filaments was successfully introduced as an extraction medium for the preconcentration of an aqueous solution of aromatic compounds. The extraction was simply carried out with pumping the aqueous sample solution to the extraction capillary at ambient temperature. The extracted analytes were sequentially eluted with a flow of pure water using temperature-programmed heating of the extraction capillary in an oven. The results clearly suggest that the polymer-coated fiber-packed capillary could be employed in the sample preparation process for the analysis of various aqueous samples. Introducing the fractions eluted from the fiber-packed capillary to a conventional microcolumn liquid chromatography (micro-LC) system via a home-made valve-based modulator, an on-line coupled extraction/separation system was developed and a possibility to a pseudo-two-dimensional (pseudo-2D) LC separation of aromatic compounds in aqueous matrices has also been demonstrated.
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