Layering for separating particles

A method for purifying target biomolecules from an aqueous phase, or for analyzing whether an aqueous phase contains target biomolecules, the method comprising:

• (a) providing a first vessel comprising a first aqueous phase, which possibly contains target biomolecules,
• (b) adding magnetic particles to the first aqueous phase, wherein target biomolecules present in the first aqueous phase bind to the magnetic particles,
• (c) binding the magnetic particles to a magnetic rod, wherein the magnetic particles are not fixed to a side of the vessel by a magnet prior to the binding,
• (d) removing the bound magnetic particles with target biomolecules bound thereto from the first aqueous phase,
• (e) transferring the magnetic particles with the target biomolecules bound thereto to a second reaction vessel comprising a second aqueous phase,
• (f) eluting the target biomolecules from the magnetic particles into the second aqueous phase,
• (g) binding the magnetic particles to a magnetic rod, wherein the magnetic particles are not fixed to a side of the vessel by a magnet prior to the binding,
• (h) removing the bound magnetic particles from the second reaction vessel using the magnetic rod, with the target biomolecules remaining in the second aqueous phase, and
• (i) when the method is for analyzing, further comprising analyzing whether the target biomolecules are present,
• wherein prior to the binding in (c) the first aqueous phase is overlaid with an organic phase, and the magnetic rod is guided through the organic phase prior to the removal of the bound magnetic particles from the first aqueous phase, and/or prior to the binding in (g) the second aqueous phase is overlaid with an organic phase, and the magnetic rod is guided through the organic phase prior to the removal of the bound particles from the second aqueous phase, and wherein the removing the bound magnetic particles in (d) and/or in (h) comprises passing the magnetic rod and the bound magnetic particles through the organic phase thereby displacing any aqueous phase from the magnetic particles so as to prevent carry-over of the aqueous phase, wherein the organic phase contains hydrocarbons and/or silicone oil.