Retention Behavior of Fluorobenzenes on Fluoro-Derivatized Poly(<i>p</i>-phenylene terephthalamide) Fibrous Stationary Phases in Microcolumn Liquid Chromatography

Abstract

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.

Preconcentration of Aromatic Compounds in Aqueous Samples with a Polymer-coated Fiber-packed Capillary and Subsequent Temperature-programmed Elution with Water for Pseudo-2D LC Separations

“…With the home-made data-processing software, the separation could be successfully expressed as 2D and 3D chromatograms. More extensive studies, including the more precise control of the trap temperature, and the development of other polymer-based materials, [28][29][30][31] are currently progressing in our laboratory, including the employment of these fibrous materials as an extraction medium in a miniaturized sample preparation technique. 32…”

Miniaturization for the Development of High Performance Separation Systems

“…In order to further enhance the compatibility of the coating materials and the fiber surface, surface modification reactions of the filaments were studied. The preliminary experiments clearly demonstrated a successful surface modification of the filaments with several types of functional groups [50][51][52], although these reaction conditions should be further optimized to realize a novel stationary phase.…”

Polyimide Filaments as a Novel Stationary Phase in Packed-Capillary Gas Chromatography

“…A bundle of fine fibrous materials was packed into a short extraction cartridge for the sample preparation of gaseous [13][14][15][16][17][18] and liquid [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] sample matrices. The use of the fibrous materials as the stationary phase was investigated in chromatographic techniques including GC [36][37][38][39][40][41][42], capillary electrochromatography [43][44][45] and liquid chromatography [46][47][48][49][50][51][52]. Fiber-packed capillary was also studied as a miniaturized interface between two-dimensional separations [53,54].…”