Document:

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                                                                   Exhibit 10.20

                                               [AMERSHAM PHARMACIA BIOTECH LOGO]

August 4, 2000

Mr. William Sulinski
136 Birch Lane
Bloomsbury, NJ 08885

Dear Bill:

     APBiotech Inc. (the "Company") is pleased that you have agreed to fill the
position of acting global head of Business Development until a permanent
replacement is hired. We confirm our agreement as follows, effective August 1,
2000:

     1.   You will temporarily be employed as the Acting VP -- Global Business
          Development ("Acting VP"). You will continue in that role until the
          position is filled. When the position is filled, you will resume your
          current responsibilities as VP -- Business Development, North America.

     2.   As Acting VP, you will report to the Chief Executive Officer of the
          Company, Andrew Carr.

     3.   While you are Acting VP, you will receive supplemental compensation of
          $2000/month above your current salary of $13,813.80/month. Your
          appointment as Acting VP will last a minimum of three (3) months. For
          purposes of earning supplemental compensation, you will be deemed to
          have worked a particular month if you remain in the position of Acting
          VP until the fifteenth (15th) date of any month. The supplemental
          compensation will be pension eligible in accordance with the Company's
          pension plan but will not be factored in the determination of your
          bonus. The Company at its sole discretion may grant you an additional
          bonus.

     4.   You will continue receiving your current benefits in accordance with
          Company policies. All payments contemplated by this letter will be
          subject to applicable withholdings and shall be made in accordance
          with the Company's standard payroll practices. You will participate in
          the Company's bonus plan and will be eligible for annual merit
          increases at the discretion of the Company.

     5.   The Company agrees that you will continue to be employed through
          September 30, 2002. Notwithstanding the foregoing, the Company may
          terminate your employment for cause, at any time, with no prior
          notice. Cause shall include, without limitation, engaging in any acts
          of negligence, misconduct, violation of Company rules, conduct which
          is injurious to the Company or conduct which is in violation of the
          directions of the Board of Directors or your superiors.

                     Amersham Pharmacia Biotech Inc.   tel 732-457-8000
                               800 Centennial Avenue   fax 732-457-8474
                                         PO Box 1327
                                          Piscataway
                                          New Jersey   web-site
                                          08855-1327   http://www.apbiotech.com
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                      [ AMERSHAM PHARMACIA BIOTECH LOGO ]

August 4, 2000
Page - 2 -

     6.   In the event that the Company terminates your employment for cause, or
          in the event that your employment terminates as a result of your
          resignation, death or disability prior to September 30, 2002, this
          Agreement shall terminate and no salary or additional payment shall be
          due for the period beyond the termination date.

     7.   All other policies and procedures of the Company will continue to
          apply with respect to your employment with the Company.

     8.   In consideration of the above, you agree to the terms and conditions
          in the attached Covenant Not to Compete.

     Please sign and return to us one original of this letter and of the
Covenant Not to Compete to confirm your acceptance.

                                             Sincerely,

                                             /s/ Glenn Melrose
                                             -----------------------------------
                                                 Glenn Melrose
                                                 Vice President, Human Resources

Acknowledged and Agreed:

/s/ William Sulinski
-----------------------------------
    William Sulinski

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                            COVENANT NOT TO COMPETE

   THIS COVENANT NOT TO COMPETE (the "AGREEMENT") made as of the 4 day of
August 2000, by and between Amersham Pharmacia Biotech Inc., a Delaware
corporation with its principal place of business at 800 Centennial Avenue,
Piscataway, New Jersey 08855 (the "EMPLOYER") and William J. Sulinski, an
individual residing at 136 Birch Lane, Bloomsbury, New Jersey 08885 (the
"EMPLOYEE").

                                  WITNESSETH:

   WHEREAS, the Employer and the Employee have entered into that certain letter
agreement of even date hereof (the "LETTER AGREEMENT"), whereby the Employee
has been appointed as the Acting VP-Global Business Development.

   WHEREAS, in his capacities as Acting VP-Global Business Development and
VP-Business Development, North America, the Employee has and will receive
information about the Employer's operations, finances and strategies of a
highly confidential nature, which he has agreed to maintain confidential; and

   WHEREAS, in consideration of the terms of the Letter Agreement, and in order
to protect the Employer's confidential information, its competitive position in
the marketplace, its ability to implement its strategies, its employee and
customer relations, and its goodwill, the Employee is wiling to covenant that
he will not compete with the Employer or solicit its employees or customers, on
the terms and conditions set forth in this Agreement.

   NOW, THEREFORE, in consideration of the above premises and of the premises
contained herein, the Employer and the Employee agree as follows:

   1. Definitions:

   (a) COMPANY means the Employer and its affiliates and subsidiaries.

   (b) PROHIBITED BUSINESS means all or any of the research, manufacture or
supply of life science products and services for the purpose of DNA sequencing
or drug development, including without limitation the research, manufacture or
sale of chromatography and electrophoresis systems for DNA synthesis.

   (c) PROHIBITED COMPANY means companies engaged in or about to be engaged in
Prohibited Business.

   (d) RESTRICTED PERIOD means the period of twelve (12) months commencing from
the Termination Date.

   (e) TERMINATION DATE means the date on which the Employee's employment with
the Employer shall terminate irrespective of the cause or manner.

   (f) TERRITORY means the United States of America, the European Union, Norway,
Switzerland, Australia, Japan and Russia.

   2. Covenant Not to Compete

   In consideration of the terms of the Letter Agreement and of the premises set
forth herein, the Employee hereby agrees that he will not, directly or
indirectly, during the Restricted Period and within the Territory:

  (a) Be employed by, or provide consulting services to: (i) a Prohibited
Company; or (ii) any business that is otherwise in competition with the
Employer; provided that this restriction shall not extend to any employment the
performance of which could not involve the Employee in competition with the
Employer;

  (b) Entice away or solicit any person who is employed or engaged by the
Employer either: (i) as a director or in a managerial, executive or senior
technical capacity; or (ii) who is in possession of confidential information
belonging to the Employer; and

  (c) Entice away or solicit a customer of the Employer with whom the Employee
has had business dealings or personal contact during his employment with the
Employer.

  3. Remedies

  If the Employee shall breach, or threaten to commit a breach of any of the
covenants set forth in this Agreement, the Employer shall have the right, in
addition to, and not in lieu of, any other rights and remedies available to the
Employer under law or in equity, to:
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     (a) have the covenants specifically enforced by any court, including,
without limitation, the right to seek entry against the Employee of restraining
orders and injunctions (preliminary, mandatory, temporary and permanent) against
violations, threatened or actual, and whether or not then continuing, of the
covenants, it being acknowledged and agreed that any such breach or threatened
breach will cause irreparable injury to the Employer and that money damages will
not provide an adequate remedy to the Employer; and

     (b) cease making any payments then otherwise due to the Employee. The
parties hereby acknowledge and agree that any such payments are conditioned upon
the Employee's compliance with the terms of this Agreement.

     4.  Blue-Penciling

     If any court determines that any of the covenants contained in this
Agreement, or any part thereof, are unenforceable because of the duration or
scope of such provision, the duration or scope of such provision, as the case
may be, shall be reduced so that such provision becomes enforceable and, in its
reduced form, such provision shall then be enforceable and shall be enforced.

     5.  Miscellaneous

     (a) This Agreement supersedes all previous agreements between the Employee
and the Employer, or any affiliate or subsidiary of the Employer, in relation to
the matters addressed herein. This Agreement represents the entire understanding
between the parties hereto with respect to the subject matter hereof. The
Employee acknowledges and agrees that he has not entered into this Agreement in
reliance upon any representation, warranty or undertaking which is not set out
or referred to in this Agreement.

     (b) The invalidity or unenforceability of any provisions of this Agreement
shall not affect the other provisions, and the Agreement shall be construed in
all respects as if such invalid or unenforceable provisions were omitted.

     (c) Any notice required or permitted to be given under this Agreement shall
be sufficient if in writing and if delivered at the addresses first above stated
by: (a) personal delivery; (b) registered or certified mail, return receipt
requested; or (c) Federal Express or other similar nationally known overnight
delivery service.

     (d) The rights and obligations of the Employee under this Agreement shall
inure to the benefit and shall be binding upon the successors and assigns of the
Employer, including any successors by merger, purchase or otherwise. The
Agreement may not be assigned by the Employee. Any attempted assignment in
breach of this provision shall be null and void.

     (e) This Agreement shall be governed by the laws of the State of New
Jersey, except for its conflicts of law rules, and all disputes arising from or
relating to this Agreement shall be resolved in the state or federal courts
located in the State of New Jersey.

     (f) This Agreement cannot be changed orally but only by an agreement in
writing signed by the party against whom enforcement of any waiver, change,
modification, extension or discharge is sought. No delay on the part of any
party in exercising any right, power or privilege hereunder shall operate as a
waiver thereof, nor shall any waiver on the part of any party of any such right,
power or privilege nor any single or partial exercise of any such right, power
or privilege, preclude any other or further exercise thereof or the exercise of
any such other right, power or privilege.

     (g) The headings herein are for reference purposes only and shall not
affect in any way the meaning and interpretation of this Agreement.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

AMERSHAM PHARMACIA BIOTECH INC.                  WILLIAM J. SULINSKI

By: /s/ Glenn R. Melrose                         /s/ William J. Sulinski
    ----------------------------------           -------------------------------
      (Signature)                                     (Signature)

Name: Glenn R. Melrose
      --------------------------------
      (Please Print)

Title: Vice President, Human Resources
       -------------------------------<PAGE>   1
                                                                   Exhibit 10.21

                              EMPLOYMENT CONTRACT

Agreement has this day been made between Amersham Pharmacia Biotech,
hereinafter called "the Company", and Mr. Peter Ehrenheim hereinafter called
"the Employee".

SECTION 1 EMPLOYMENT AND EMPLOYEE'S OBLIGATIONS

          The Company promotes the Employee to the position as vice president,
          Separations. The Employee takes up his new position as from 1 January,
          2000.

          In this capacity the Employee shall perform his duties as specified by
          the Deputy CEO.

          The Employee shall devote the whole of his working time to his duties
          under this agreement and may not undertake any other duties without a
          written consent form the Company.

          The employment is open ended. LAS - Lagen om Anstellningsskydd - is
          not applicable.

SECTION 2 REMUNERATION

2.1       Base salary

          The Employee's annual base salary shall be SEK 960,000 (nine hundred
          and sixty thousand) payable according to local practice. The salary
          will be reviewed annually, and change will be effective 1 January.
          First review will be effective 1 January, 2001. On this occasion, the
          annual base salary shall be increased with 8,5% in excess of the
          average management increase for Swedish senior managers, excluding
          members of the Executive Management Team, providing satisfactory
          performance has been achieved by the Employee.

          Any bonuses, gifts or other payments which the Company may grant or
          make to the Employee from time to time, to the extent that they are
          not required by law or by this contract, shall be treated as having
          been granted or made at the Company's absolute discretion and shall
          not be considered a part of the employee's contractual remuneration.

2.2       Bonus payments

          The Employee will be entitled to a payment based upon performance by
          the Employee. Associated conditions will be in line with Group policy.
          Maximum bonus amount is 30 per cent of the base salary. Details
          regarding objectives and incentives will be settled in a separate
          agreement.

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2.3       Company car

          The Employee is entitled to a Company car for business and private
          use. All conditions related to the car will be in line with the
          Company car policy.

SECTION 3 EXPENSES

          The Company will reimburse the Employee for all reasonable business
          expenses incurred by him during the course of the employment. The
          Employee must provide receipts and other evidence of such business
          expenses.

SECTION 4 PENSION AND INSURANCE COVERAGE

          The Employee is retained in the ITP plan.

SECTION 5 HOLIDAY ENTITLEMENT

          The Employee is entitled to 30 days holiday in any calendar year.

SECTION 6 SOCIAL SECURITY CONTRIBUTIONS AND INCOME TAXES

          The Employee will pay tax and social security contributions in
          accordance with Swedish regulations and the Company will withhold the
          necessary deductions for this.

SECTION 7 TERMINATION OF CONTRACT

          The contract may be terminated by either party giving to the other
          6 months advance notice in writing. The Company reserves the right to
          remove the Employee from his position during the time of notice or
          part of it. During the time of notice the Employee is entitled to the
          conditions of this agreement with the exception of bonus.

          Should the contract be terminated by the Employer during the period
          1 January 2000 to 31 December 2002, the Employee shall receive in
          addition to time of notice a severance pay amounting to 24 months
          salary as per date the day before giving notice. Should the contract
          be terminated by the Employer on 1 January 2003 or later, the
          severance shall amount to 12 months salary as per date the day before
          giving notice. The severance pay shall, unless otherwise agreed upon,
          be paid every month starting the first month after the expiry of the
          employment.

          The Company reserves the right to terminate this contract at any time
          without advance notice in the event of serious breach of contract,
          including act of gross negligence or gross misconduct by the Employee
          and willful failure to perform his duties with the Company.
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SECTION 8 CONFIDENTIALITY

          The Employee shall not at any time other than in the course of his
          duties without the previous consent in writing of the Company divulge
          or make known to anyone any secrets or any technical, commercial,
          financial or other information of a confidential nature unless such
          information is already in the public domain relating to the business
          or customers of the Group so as to the extent that all such
          information has become a matter of public record. All papers and
          documents used by the Employee in the course of his employment are and
          will remain the property of the Company and will be delivered up to
          the Company on the termination of the Employee's agreement with the
          Company or any of its subsidiaries. This clause operates
          independently of the existence of this Agreement.

SECTION 9 PATENT, SECRET PROCESSES AND IMPROVEMENTS

          Any discovery or invention or secret process or improvement in
          procedure made or discovered by the Employee while in the service of
          the Company whether before or after the date of this Agreement in any
          way affecting or relating to the business of the company or of any
          subsidiary company or capable of being used or adapted for use therein
          or in connection therewith shall forthwith be disclosed to the Company
          and should belong to and be the absolute property of the Company.

SECTION 10 RESTRICTIVE COVENANT

          The Employee hereby agrees during his employment not to solicit
          business from any person, firm or company who is or at any time has
          been a customer or done business with or attempt to persuade away from
          the Company any person who is or has been employed by the Company.

SECTION 11 JURISDICTION

          Any dispute about the Agreement shall be submitted to a Swedish
          Arbitration court if the parties cannot come to a consensus as to the
          interpretation of the conditions. The costs for the arbitration
          proceedings shall be defrayed by the Company provided the Employee has
          not unduly instigated the arbitration procedure. In such case, the
          arbitrators shall determine the distribution of arbitration costs.

SECTION 12 OTHER EMPLOYMENT CONDITIONS

          This contract supersedes all previous agreements between the Company
          and the Employee. As regards employment conditions that are not
          regulated in this contract the policies of the Company shall apply.
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Section 13     COUNTERPARTS

               The agreement has been drawn up in duplicate of which the
               parties have taken one copy each.

     Signed   /s/ Arne Forsell                    /s/ Peter Ehrenheim
              ------------------------------      ----------------------------
                  Arne Forsell                        Peter Ehrenheim
                  Deputy CEO
                  Amersham Pharmacia Biotech

                  23/11 '99                       24/11-99
                  --------------------------      ----------------------------
                  date                            date

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