http://www.electrosynthesis.com/ess/weid.html (http://www.electrosynthesis.com/ess/weid.html)
) using a cation permeable membrane could be used to extract p-eph from pill mess or possibly eph from plant mess, for example using a polystyrene sulphonic acid membrane the negative cell containing dilute acid, the positive cell containg slightly acidic pill solution.