An aqueous liquid preparation containing –4-4-methoxypiperidinobutyric acid or a pharmacologically acceptable acid addition salt thereof, which is stabilized with a water-soluble metal chloride, is provided. A CATV terminal can be routed to cellular network by way network coupling devices. A gate electrode surrounds the channels and extends through the at least one tunnel. The integration of a solid phase material with a digital microfluidic array enables a wide range of applications including solid phase extraction and sample concentration. In particular the present invention relates to the synthesis of an optically active alcohol of general formula.