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

High 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 [2-4]. 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. Jinno and co Original