A process for manipulating magnetic particles that are suspended in a fluid, possibly containing a biological entity of interest, the magnetic particles being able to bind the entity of interest, the fluid being contained in a reaction vessel constituted by a large upper compartment with a funnel shape, an elongate lower compartment with a substantially constant cross-section (5, 6) and a closed base, consisting of: a) subjecting the magnetic particles to two magnets each generating a magnetic field which magnetic fields are simultaneously applied to the funnel-shaped upper compartment of the vessel, in order to collect the magnetic particles present in at least the funnel-shaped upper compartment of the vessel from the fluid at two positions of the sidewall of upper compartment corresponding to the position of the two magnets, b) transferring the separated magnetic particles from the upper compartment to the elongated lower compartment (5, 6) by moving the two magnets relative to the reaction vessel, in order to join the magnetic particles at one position of the sidewall of the elongate lower compartment, c) removing the fluid from the vessel, d) adding a washing liquid to the lower compartment (5, 6), e) subjecting the rest of the fluid to at least two magnetic fields applied successively with different and changing directions to wash all the magnetic particles present in the lower compartment (5, 6), and f) concentrating said magnetic particles in said lower compartment (5, 6); wherein the upper compartment comprises a first part having a constant cross section and a first funnel-shaped part, wherein the size of a cross section of the first part is larger than the size of a cross section of the elongate lower compartment (5, 6), wherein the longitudinal axis of the first part is parallel to but spaced apart from the longitudinal axis of the lower compartment (5, 6), wherein, during step a), the two magnets are arranged at a side of the first part and at an opposing side of the first funnel-shaped part. a) subjecting the magnetic particles to two magnets each generating a magnetic field which magnetic fields are simultaneously applied to the funnel-shaped upper compartment of the vessel, in order to collect the magnetic particles present in at least the funnel-shaped upper compartment of the vessel from the fluid at two positions of the sidewall of upper compartment corresponding to the position of the two magnets, b) transferring the separated magnetic particles from the upper compartment to the elongated lower compartment (5, 6) by moving the two magnets relative to the reaction vessel, in order to join the magnetic particles at one position of the sidewall of the elongate lower compartment, c) removing the fluid from the vessel, d) adding a washing liquid to the lower compartment (5, 6), e) subjecting the rest of the fluid to at least two magnetic fields applied successively with different and changing directions to wash all the magnetic particles present in the lower compartment (5, 6), and f) concentrating said magnetic particles in said lower compartment (5, 6); wherein the upper compartment comprises a first part having a constant cross section and a first funnel-shaped part, wherein the size of a cross section of the first part is larger than the size of a cross section of the elongate lower compartment (5, 6), wherein the longitudinal axis of the first part is parallel to but spaced apart from the longitudinal axis of the lower compartment (5, 6), wherein, during step a), the two magnets are arranged at a side of the first part and at an opposing side of the first funnel-shaped part.