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                                                                  Exhibit 10.3.1

                       ASSIGNMENT AND ASSUMPTION AGREEMENT



          This Assignment and Assumption Agreement (this "Agreement") is entered
into as of August 24, 2001, by and between SeraCare, Inc., a Delaware
corporation (the "SeraCare"), SeraCare Life Sciences, Inc., a California
corporation ("Life Sciences") and Michael Crowley Jr., an individual
("Crowley.")

          WHEREAS, SeraCare and Crowley are parties to that certain Employment
Agreement, dated November 1, 2000 (the "Employment Agreement");

          WHEREAS, on June 10, 2001, SeraCare entered into an Agreement and Plan
of Merger with Instituto Grifols. S.A. and SI Merger Corp. (the "Merger
Agreement");

          WHEREAS, pursuant to the terms of the Merger Agreement, at the
Effective Time (as defined in the Merger Agreement) SI Merger Corp will be
merged into SeraCare with SeraCare as the surviving corporation (the "Merger")
and SeraCare shall become a wholly owned subsidiary of Instituto Grifols;

          WHEREAS, the Merger is conditioned upon, among other things, the prior
spin-off by SeraCare of Life Sciences, pursuant to which each stockholder of
record of SeraCare on the record date for the spin-off will receive two shares
of the common stock of Life Sciences for every five shares of SeraCare held of
record by such stockholder (the "Spin-Off");

          WHEREAS, the parties desire to assign SeraCare's rights and
obligations under the Employment Agreement to Life Sciences, effective upon the
consummation of the Merger.

          NOW, THEREFORE, in consideration of the foregoing recitals, the
parties hereto, intending to be legally bound, agree as follows:

1.   Assignment of Rights and Obligations under the Employment Agreement.
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     a.             SeraCare hereby assigns, transfers and conveys, effective as
of the Effective Time (as defined in the Merger Agreement), to Life Sciences all
of SeraCare's rights, title and interest in and to the Employment Agreement,
including but not limited to all of SeraCare's rights and benefits thereunder.

     b.             Life Sciences hereby assumes and agrees to be bound by,
effective as of the Effective Time, all of SeraCare's obligations under the
Employment Agreement.

     c.             For the avoidance of doubt, at the Effective Time, the
following shall apply:

          i.             All references to SeraCare in the Employment Agreement
               shall mean a reference to Life Sciences.
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          ii.            SeraCare shall have no continuing obligations to
               Crowley, and Crowley shall have no continuing obligations to
               SeraCare under the Employment Agreement.

     d.             Crowley hereby consents to the assignment by SeraCare to
Life Sciences of the Employment Agreement, as provided herein.

2.   Governing Law. This Agreement shall be governed by, interpreted under, and
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construed and enforced in accordance with the internal laws, and not the laws
pertaining to conflicts or choice of laws, of the State of California.

3.   Counterparts. This Agreement may be executed in any number of counterparts,
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each of which when so executed and delivered shall be deemed to be an original
for all purposes, but all such counterparts shall constitute but one in the same
instrument.

4.   Termination. This Agreement shall terminate and be of no further force and
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effect in the event of the termination of the Merger Agreement prior to the
consummation of the Merger.



                         [SIGNATURES ON FOLLOWING PAGE]

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                  IN WITNESS WHEREOF, the undersigned parties have caused this
Agreement to be duly executed and delivered as of the date set forth above.



SERACARE:

SERACARE, INC.



By: /s/ Barry D. Plost
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    Barry D. Plost
    President and Chief Executive Officer



LIFE SCIENCES:

SERACARE LIFE SCIENCES, INC.



By: /s/ Jerry Burdick
    -----------------
    Jerry Burdick
    Chief Financial Officer



CROWLEY:

MICHAEL CROWLEY JR., an individual

/s/ Michael Crowley Jr.
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