Abstract: An apparatus adapted to extract an ingredient from a fluid sample by bidirectional transferring of an aliquot of fluid having magnetic particles therein, said apparatus comprising: an open compartment operable at a constant ambient pressure; a closed compartment having a closed pressure, and an upper zone containing an air pocket adapted to generate internal positive and negative pressure; an intermediate transferring-retaining compartment adapted to temporarily retain a fraction of said aliquot of fluid; a flow barrier member adapted to inhibit a flow of said aliquot of fluid when said closed pressure is substantially equal to said ambient pressure and to allow said flow of fluid when said closed pressure is substantially different from said ambient pressure, the pressure differential controllable by a thermo member; a capturing zone adapted to allow magnetic particles in the fluid to be attracted in response to a magnetic force applied.

Abstract: This invention concerns a method, devices, instrument and program for extraction an ingredient from a liquid sample by bidirectional transfer of an aliquot of fluid between compartments, the method can be applied to a wide variety of laboratory techniques such as; solid phase extraction by filter disc, column chromatography, magnetic separation, diagnostic tests and others, the system is suitable for single or multi sample handling, manual operation or integrated into an automated system, can be used in a lab or in field.