Braid configuration designed for fiber-packed capillary in microscale sample preparation

A novel miniaturized sample preparation device with braid-type extraction medium was successfully developed. Introducing a set of bundles of fine synthetic filaments as the materials of the braid-type extraction medium and also the application of an appropriate tension during the braiding process, the outer diameter of the resulting braid has been controlled. Optimization of the tension enables an easy preparation of a group of braids that can be well-compatible to various internal diameters of capillaries to be packed. The extraction conditions were systematically optimized, and the efficient extraction was confirmed under the optimized conditions. All the parameters affects the desorption efficiency were also optimized, where typical extraction efficiency was more than 90% for the extraction of phenanthrene (1.0 μg/mL) in water. The extracted analyte was desorbed sufficiently by employing a sequential pumping process of two organic solvents. During the preparation of the braid, a different type of fibrous materials could be inserted to the opening at the center of the braid. Taking advantage of this feature of the braid, a stainless steel wire was inserted into the center of the braid. By applying low voltages to the stainless steel wire, a heat-assisted desorption of the extracted analyte was also studied. Experimentally complete desorption (higher than 99.0%) was obtained with the voltage application of 2 V. The lowest limit of quantification (LOQ) and the lowest limit of detection (LOD) for phenanthrene were 0.048 and 0.014 μg/mL, respectively.