The OPTI-PAK™'s unique hardware design integrates a PEEK holder with an auto-adjusting stem which provides a fluid interface with any 10-32 standard injector port, and guarantees a zero-dead-volume connection despite variances in tube stop depth. A proprietary method of frit placement allows the packed stem to be positioned directly into the flow path, which eliminates all excess swept volume. Less swept volume translates to absolute minimum sample dilution and dispersion. The elegant, flexible design of OPTI-PAK™ makes it amenable to virtually any trapping application. Installing an OPTI-PAK™ into the outlet of a switching valve will facilitate the trapping, desalting, and pre-concentration of an analyte mixture. With OPTI-PAK™s versatility, a second trap can be added downstream in the loop of an injection valve and effectively perform a 2D separation.