an electrophoretic gel elutor and concentrator includes a semi - permeable collecting membrane having a continuously diminishing cross - section terminating in an apex , and a supporting frame of matching configuration . this apparatus is useful in electrophoretic extraction of biological samples which have been previously cut from a separation gel . the apparatus is used with standard electrophoresis equipment including a buffer tank , electrodes , and a power source . due to the high effective cross - section of the collecting membrane , electrophoretic elution can be carried out quickly and efficiently . due to the continuously diminishing cross - section to the apex of the collecting membrane , the biological sample is advantageously concentrated and extractions of 99 % theoretical yield from a separated gel fragment is possible .