Method and apparatus for separation of solid supports and liquid phase

• US 5,770,461 A
• Filed: 08/30/1995
• Issued: 06/23/1998
• Est. Priority Date: 09/02/1994
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sakazume, Taku, Nomura, Yasushi, Imai, Kyoko
• Primary Examiner(s): WOLSKI, SUSAN C
• Application Number:
  US08/520,781
• Time in Patent Office: 1,028 Days
• Field of Search: 435/283.1, 435/287.2, 435/287.9, 436/526, 436/806, 436/824, 209/5, 209/214, 210/222, 210/695
• US Class Current: 436/526
• CPC Class Codes: B03C 1/288 disposed at the outer circumference of a recipient
• CPC Class Codes: G01N 33/54326 Magnetic particles
• CPC Class Codes: Y10S 436/806 Electrical property or magnetic property
• CPC Class Codes: Y10S 436/824 Immunological separation techniques

Abstract

A method and apparatus for separating solid supports formed of magnetic particles on which immunocomplexes are bound, from a liquid phase includes a reaction container containing a fluid in which magnetic particles having immunocomplex bound thereon are suspended. The reaction container is positioned at a flock forming station, where the fluid is subjected to an alternate current magnetic field having a temporally varying intensity by an electromagnetic. The magnetic particles are flocculated with each other due to the application of such varying magnetic field to form a multiplicity of flocks. A stronger magnetic field then is applied to the resulting contents in the reaction container by a permanent magnet. The flocks are magnetically fixed on the inner wall surface of the reaction container by the action of the stronger magnetic field. While the magnetic particles are being fixed on the inner wall surface, a nozzle is inserted into the reaction container to suck the unnecessary liquid phase and remove it from the reaction container.

Claims

1. A method of separating magnetic particles on which an immunocomplex is bound, from a liquid phase in a container, comprising the steps of:

applying a varying magnetic field to said magnetic particles having the immunocomplex to cause said magnetic particles to be flocculated;

applying a static magnetic field to said container, in which flocculation has occurred, for magnetically fixing said magnetic particles on an inner wall of said container;

removing the liquid phase in said container while said magnetic particles are magnetically fixed on said inner wall of said container;

releasing said magnetic particles from said static magnetic field;

feeding a washing liquid into said container to suspend said magnetic particles in said washing liquid;

applying a varying magnetic field to said magnetic particles suspended in said washing liquid to cause said magnetic particles to be flocculated;

magnetically fixing said magnetic particles on said inner wall of said container by applying a static magnetic field to said washing liquid in which flocculation has occurred; and

removing said liquid phase in said container while said magnetic particles are magnetically fixed on said inner wall of said container.

2. A separating method according to claim 1, wherein said varying magnetic field has an intensity that does not cause the solid supports to be magnetically fixed on the inner wall surface of said container.

3. A separating method according to claim 1, further comprising the step of adding a flocculent in said container for promoting flocculation prior to the step of applying the varying magnetic field.

4. A separating method according to claim 3, wherein said flocculent includes magnetic particles having a diameter in the range of 10-50 μ

m, and said magnetic particles on which an immunocomplex is bound have a diameter in the range of 1-2 μ

m.

5. An apparatus for separating magnetic particles on which an immunocomplex is bound, from a liquid phase in a container, comprising:

means for moving said container through a B-F (Bound-Free) separation station, a washing station and a photometric station;

means for applying an alternate current magnetic field to said container to cause said magnetic particles to flocculate;

means for applying a static magnetic field to said container in which the magnetic particles have been flocculated, whereby said magnetic particles are magnetically fixed onto an inner wall of said container; and

means for removing said liquid phase from said container while said magnetic particles are magnetically fixed on said inner wall of said container.

6. A separating apparatus according to claim 5, wherein said means for applying said static magnetic field includes a permanent magnet.

7. A separating apparatus according to claim 5, further comprising means for feeding said container with a flocculent prior to applying said alternate current magnetic field.

8. A separating apparatus according to claim 5, further comprising means for feeding said container with a washing liquid after the liquid phase has been removed from said container.