<PAGE>
                                                                   Exhibit 10.46


                                EIGHTH AMENDMENT
                                     TO THE
                      FISHER SCIENTIFIC INTERNATIONAL INC.
                                 RETIREMENT PLAN

      WHEREAS, Fisher Scientific International Inc. (the "Company") has
established and maintains the Fisher Scientific International Inc. Retirement
Plan (the "Plan"); and

      WHEREAS, the Fisher Scientific International Inc. Administrative and
Investment Committee (the "Committee") has the authority pursuant to Section
10.1 of the Plan to amend the Plan;

      WHEREAS, the Committee desires to amend the Plan to permit the continued
eligibility of employees of Fisher Scientific International Inc. and its
subsidiaries in the Plan following a transfer to employment with Apogent
Technologies, Inc. or its subsidiaries following the merger of the Company and
Apogent Technologies, Inc.; and

      WHEREAS, the Committee desires to further amend the Plan to exclude
employees of Apogent Technologies, Inc. and its subsidiaries from eligibility in
the Plan who (1) become employees of the Company or a Participating Company (as
described in Schedule I to the Plan) following the merger of the Company and
Apogent Technologies, Inc; and (2) are eligible to participate in any of the
following plans prior to their transfer of employment: (A) Apogent Retirement
Security Plan, (B) Pension Plan for Employees of Chase Scientific Glass, Inc.,
or (C) Retirement Plan of Barnstead Thermolyne Corporation for Employees Covered
by a Collective Bargaining Agreement.

      NOW, THEREFORE, be it resolved as follows:

      RESOLVED, the Plan shall be amended effective as of the date of this
Amendment as follows:

      Section 1.17 of the Plan is hereby amended in its entirety to read as
follows:

      1.17  "Eligible Employee" means any Employee of the Company other than an
Employee who is (a) covered by a collective bargaining agreement between a union
and a Company; provided, however, that retirement benefits were the subject of
good faith bargaining, (b) a leased employee within the meaning of section
414(n)(2) of the Code, (c) an Employee who is eligible to participate in the
Fisher Scientific International Inc. Executive Retirement and Savings Plan, as
amended and restated June 23, 1997, and (d) an Employee who is eligible to
participate in one or more of the following plans: (1) Apogent Retirement
Security Plan, (2) Pension Plan for Employees of Chase Scientific Glass, Inc.,
or (3) Retirement Plan of Barnstead Thermolyne Corporation for Employees Covered
by a Collective Bargaining Agreement (collectively, the "Apogent Pension Plans")
by virtue of their transfer of employment from Apogent Technologies, Inc. or its
subsidiaries and affiliates on or after the Closing Date (as defined in the
Amended and Restated Agreement and Plan of Merger by and among Fisher

<PAGE>

Scientific International Inc., Fox Merger Corporation and Apogent Technologies,
Inc. dated as of March 17, 2004 as Amended April 16, 2004). Notwithstanding the
foregoing, an Employee who is covered by a collective bargaining agreement
between a union and a Company may be an Eligible Employee in accordance with the
provisions of Schedule B.

      In addition, an Eligible Employee who transfers employment to Apogent
Technologies, Inc. or a U.S. subsidiary on or after the Closing Date shall
remain an Eligible Employee under this Plan and shall continue to earn Years of
Service for vesting purposes and accrue benefits under the Plan on the same
basis and same terms as the Employee received immediately prior to his transfer
of employment.

      RESOLVED, FINALLY, that all other provisions of the Plan shall remain in
full force and effect.

      IN WITNESS WHEREOF, the Fisher Scientific International Inc. Retirement
Plan is amended this 22nd day of July, 2004.

                                                   ADMINISTRATIVE AND INVESTMENT
                                                   COMMITTEE

                                                   /s/ Paul M. Meister
                                                   _____________________________
                                                   Paul M. Meister


                                                   /s/ Todd M. DuChene
                                                   _____________________________
                                                   Todd M. DuChene