In-Valve Sample Preparation Cartridge Designed for Microcolumn Liquid Chromatography

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

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.

Bio-sample preparation and analytical methods for the determination of tricyclic antidepressants

An extended and comprehensive review is presented herein, focusing on sample preparation (pretreatment and extraction) and different analytical methods applied for the quantification of tricyclic antidepressants. These procedures are relevant tools in clinical and forensic toxicology. It is revealed that SPE, for sample preparation, and HPLC, using reversed-phase alkyl (C18) or cyanopropyl-bonded silica columns for the analytes separation, are effective and versatile methods for assay of tricyclic antidepressants. These methods enable achievable detection limits using UV/diode array detection, readily available in most laboratories, down to 1–8 ng ml-1, and using electron capture detection better than 1 ng ml-1, which is lower than that for nitrogen–phosphorus detector. MS interfaced with electrospray ionization offered similar sensitivity, whilst sonic spray ionization provided detection down to 0.03 ng ml-1. A brief discussion on chemical structures, metabolism and mechanism of action of this group of drugs is also presented.

Surface derivatization of poly(p-phenylene terephthalamide) fiber designed for novel separation and extraction media

The surface derivatization of poly(p-phenylene terephthalamide) fiber was studied. The obtained surface-derivatized filaments were packed into a fused-silica capillary to evaluate its surface characteristics by using GC. As the stationary phase for GC the surface-derivatized fibers showed higher retention for alkanes and alkylbenzenes than that with the untreated Kevlar fiber. The improvements on the retention power and the peak shape were observed on the benzyl-modified fibrous stationary phase. The derivatized fibrous materials were also evaluated as the extraction medium in fiber-in-tube SPE, and the effect of the surface modification on the extraction power was compared to the parent fiber. The results indicated that the modified fiber possessed a higher extraction power than the untreated fiber. Based on the facts, the successful modification of the fiber surface was estimated.