<PAGE>   1
                                                                   EXHIBIT 10.13

                         PROCESS DEVELOPMENT CONSORTIUM
                              MEMBERSHIP AGREEMENT

     This Agreement is entered into as of February 26, 1999 (the "Effective
Date"), by and between Argonaut Technologies, Inc., a Delaware corporation with
its principal place of business at 887 Industrial Road, Suite G, San Carlos,
California 94070 ("Argonaut"), and Agouron Pharmaceuticals, Inc., a California
corporation with its principal place of business at 10350 North Torrey Pines
Road, La Jolla, California 92037-1020 ("Member").

     WHEREAS, Argonaut has expertise in the development of instrumentation
utilizing automated, diverse reaction chemistries for the preparation of small
organic molecules;

     WHEREAS, Argonaut has established a Process Development Consortium ("PDC")
to consist of Argonaut and up to ten (10) members that are companies in the
pharmaceutical, biotechnology, and chemical industries, for the purpose of
discussing and identifying desirable features, concepts and designs for
automated process development systems to facilitate the development of automated
process development instrumentation;

     WHEREAS, the Member wishes to be a member of the PDC, on the terms and
conditions herein.

     NOW THEREFORE, the parties agree as follows:

                                       1
                                  DEFINITIONS

1.1  "Affiliate" shall mean any corporation, company or other entity of which a
party directly or indirectly owns or controls stock entitled to at least fifty
percent (50%) of the votes at a shareholders' meeting or is otherwise entitled
to directly or indirectly elect or appoint at least fifty percent (50%) the
governing body.

1.2  "Confidential Information" shall mean any proprietary information of
Member or Argonaut, which shall be kept in strict confidence between them, and
restricted from disclosure to any third party, including any other member of the
PDC, as further defined in Section 8.1.

1.3  "Information" shall mean technical data, business information, designs,
concepts, algorithms, processes, formulae, know-how, drawings, prints,
specifications, and other information.

1.4  "Instrument" shall mean a fully operational, automated process chemistry
development system, including software, that is designed or developed solely by
Argonaut, or jointly by Argonaut and one or more members of the PDC, under this
Agreement. The Instrument shall meet the specifications set forth in Exhibit A,
which may be amended by mutual written agreement of the parties. The
Instrument, including software, shall not incorporate any PDC member's
Confidential Information, except that an Instrument may be customized, solely
for delivery to a particular PDC
<PAGE>   2
member with such PDC member's consent, to incorporate any of such PDC member's
Confidential Information.

1.5     "Patents" shall mean all patent applications filed in any country of the
world, including continuations, divisionals, continuations-in-part, continued
prosecutions, and any patents issuing thereon, including any extensions,
registrations, confirmations, reissues, reexaminations and renewals thereof,
claiming any inventions or discoveries made solely by Argonaut, or jointly by
Argonaut and Member (alone or in conjunction with one or more other members of
the PDC) in connection with the activities of the PDC.

1.6     "Prototype" shall mean any pre-production version of the Instrument,
including, but not limited to, a beta prototype, which is not designated by
Argonaut for commercial release.

                                       2
                               PURPOSE AND FORMAT

2.1     Objective. The objective of the PDC will be to combine the expertise in
chemistry of accomplished chemistry groups from members with Argonaut's
expertise in automated systems for the purpose of enhancing the development of
Instruments to be delivered to PDC members that will facilitate their
implementation and use of such Instruments for chemical process development.

2.2     Membership. The PDC shall have, in addition to Argonaut, no more than
ten (10) and no less than seven (7) members, including Member.

2.3     Meetings. The PDC will meet quarterly during the term of this Agreement
at Argonaut's facilities in San Carlos, California, or another mutually agreed
site. In addition, Argonaut may meet with Member individually, as agreed by
Argonaut and such Member. Each party shall pay its own costs incurred in
connection with such meetings. Argonaut will be responsible for managing the
PDC, including conducting the quarterly meetings, setting agendas, and
providing the format for the discussion and exchange of ideas. Argonaut will
bear the cost of the meeting facilities.

                                       3
                            OBLIGATIONS OF ARGONAUT

3.1     PDC Management. Argonaut shall be responsible for the organization and
coordination of the PDC, including the oversight of all aspects of the
day-to-day management of the PDC and control of its overall scientific
direction. Argonaut will appoint an Argonaut employee (the "Director") to
direct and coordinate the work of the PDC. The Director will be the primary
point of communication and coordination between Argonaut and the other members
of the PDC, including Member.

3.2     Use of Payments. Argonaut shall use the payments made by Member
pursuant to Article 9 solely in connection with activities relating to meeting
the objective of the PDC, including, but not limited to, the manufacture,
installation, and support of an Instrument to be delivered to Member.


                                      -2-

<PAGE>   3
Argonaut agrees to maintain Member's payments as a liability on Argonaut's
books consistent with Section 9.3 until such time as these funds may be
recognized as revenue under Generally Accepted Accounting Principles. The price
of the Instrument to the Member shall be at or below the advertised commercial
list price for the Instrument. The Member shall take delivery of one (1)
Instrument once the Instrument is commercially released. Title shall pass to
Member FOB shipping point. The Member shall be responsible for all applicable
taxes, duties, VAT and freight charges in addition to the consideration
referenced in Section 9.1.

3.3     Y2K Compliance. Argonaut represents and warrants that the any and all
computer software components of the Instrument ("software") will be designed to
be used prior to, during, and after the calendar year 2000 A.D., and that the
Software will operate during each such time period without error relating to
date data, specifically including any error relating to, or the product of,
date data which represents different centuries or more than one century.

                                       4
                             OBLIGATIONS OF MEMBER

4.1     Member Representative. Member shall appoint at least one qualified
scientist to attend PDC meetings on behalf of Member. The salary, benefits
and expenses of any such individual will be borne by Member.

4.2     Member Information. In connection with this Agreement, Member shall
provide Argonaut with such Information relating to process chemistry as Member
in its sole discretion deems appropriate to accomplish the objectives of the
PDC. Any portion of such Information, including without limitation, information
relating to chemical synthesis routes, reagents, linkers and applications
results, may be designated as Confidential Information, subject to Article 8
below. Member's Information marked as "CONFIDENTIAL" or with a similar notation
shall be treated as Confidential Information, and may not be disclosed by
Argonaut to any third party or to any other PDC member without the prior
written consent of Member. Member's Information not marked "CONFIDENTIAL" may
be disclosed by Argonaut to all PDC members.

4.3     Due Diligence. Member shall use reasonable efforts to participate in
PDC meetings and provide advice regarding the design of the Instrument.

                                       5
                                   PROTOTYPES

5.1     Prototypes. Member will have an opportunity to use a Prototype,
including software, at Argonaut's San Carlos, CA facility on a scheduled and
regular basis, in order to test its suitability for Member's use.


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                                       6
                                    LICENSES

6.1  No Implied Licenses. Except as expressly provided in this Agreement, the
disclosures hereunder of any Information, including a Confidential Information,
shall not be construed to grant a license of any type under any patents,
copyrights, trade secrets, trademarks, or know-how owned or controlled by such
contributing PDC member, to Argonaut, Member or any other member of the PDC.
Member and Argonaut each agree that it will not use the other's Confidential
Information disclosed hereunder to file any patent applications or support any
existing patent applications, except that each member of the PDC may file and
prosecute patent applications covering compounds independently discovered by
such member using an Instrument (including any Prototype) or covering chemical
syntheses or processes independently discovered by such member using an
Instrument (including any Prototype).

6.2  Most Favored Member. Argonaut represents and warrants that each PDC
agreement entered by and between Argonaut and each member of the PDC contains
materially the same terms, and that if Argonaut should grant to one or more PDC
members terms substantially better than those of this Agreement, when taken as
a whole, this  Agreement shall be considered amended to provide Member the
benefit of said materially better terms.

                                       7
                             INTELLECTUAL PROPERTY

7.1  Ownership. Except as set forth below, the ownership of intellectual
property rights to any inventions, know-how, or trade secrets discovered or
developed solely by Argonaut in the activities under this Agreement shall be
owned solely by Argonaut; and the ownership of intellectual property rights to
any inventions, know-how, or trade secrets discovered or developed jointly by
two or more PDC member (e.g., Argonaut and Member) in the activities under this
Agreement shall be owned jointly by such PDC members. For any inventions
discovered or developed jointly by two or more PDC members, such PDC members
shall mutually determine how to control, and allocate the expenses for, the
preparation, filing, prosecution, maintenance, defense, and enforcement of any
Patents covering such inventions.

7.2  Rights in Instrument. Notwithstanding Section 7.1, it is agreed that
Argonaut shall have the sole and exclusive right to commercialize any
Instrument, as well as replacement hardware and software components thereof,
discovered or developed in the PDC activities under this Agreement solely by
Argonaut or jointly by Argonaut and one or more of the other PDC members. To
that end, Member hereby grants Argonaut an exclusive, perpetual, royalty-free,
fully paid-up license, with the right to grant sublicenses, under Member's
interest in any jointly owned intellectual property rights of Argonaut and
Member, directly relating to Instrument, to develop, manufacture, sell and
otherwise commercialize Instrument, including replacement hardware and software
components thereof. It is understood and agreed that Member shall retain its
entire right, title and interest in any other jointly owned intellectual
property relating to inventions, trade secrets, or know-how discovered or
developed in the PDC activities under this Agreement, including without

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limitation, inventions, trade secrets, and know-how that do not directly relate
to the Instrument, such as those relating to chemistries discovered or
developed using Instrument. Argonaut may itself or with third parties utilize
its solely owned or jointly owned intellectual property rights under this
Agreement to develop, manufacture and sell Instruments and replacement hardware
and software components thereof, and otherwise commercialize such intellectual
property rights, without obligation or compensation to Member.

7.3  Rights in Chemistries. Argonaut acknowledges that Member shall be the sole
and exclusive owner of all intellectual property rights covering any
chemistries, including, but not limited to, compounds and reaction routes or
synthetic processes, discovered or developed solely by Member using any
Instrument, including any Prototype, under this Agreement or otherwise
discovered or developed solely by Member. The PDC members agree that,
notwithstanding any other provision in this Agreement, no PDC member shall be
entitled to commercialize any chemistries, including compounds and reaction
routes or synthetic processes, discovered or developed in the PDC activities
jointly by such PDC member and one or more other PDC members without each such
other PDC member's written consent. Notwithstanding any other provision of this
Agreement, Argonaut agrees to retain in perpetuity any of Member's Confidential
information relating to proprietary chemistries, such as compounds and/or
reaction routes or synthetic process for preparing compounds.

                                       8
                                CONFIDENTIALITY

8.1  Confidential Information. In connection with the performance of this
Agreement, Argonaut or Member may disclose confidential or proprietary
technical or business Information to the other. Each party shall use its best
efforts to mark its Confidential Information provided in tangible form
hereunder with a "CONFIDENTIAL" notation or other similar marking. For such
Information disclosed orally, the disclosing party shall use its best efforts,
within thirty (30) days of such oral disclosure, to summarize such Information
in a writing, with such summary bearing appropriate marking(s) as indicated
above to indicate its confidential nature.

8.2  Confidentiality Obligations. Except as expressly provided herein, the
parties agree that, for the term of this Agreement and for five (5) years
thereafter, the receiving party shall keep completely confidential and shall
not publish or otherwise disclose and shall not use for any purpose except for
the purposes expressly permitted by this Agreement any Confidential Information
furnished to it by the disclosing party hereto pursuant to this Agreement,
except that to the extent that it can be established by the receiving party by
competent proof that such Confidential Information:

          8.2.1  was already known to the receiving party, other than under an
obligation of confidentiality, at the time of disclosure;

          8.2.2  was available to the public or otherwise part of the public
domain at the time of its disclosure to the receiving party;

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                8.2.3   became available to the public or otherwise part of the
public domain after its disclosure and other than through any act or omission
of the receiving party in breach of this Agreement;

                8.2.4   was independently developed by the receiving party as
demonstrated by documented evidence prepared contemporaneously with such
independent development; or

                8.2.5   was subsequently lawfully disclosed to the receiving
party by a third party.

8.3     Notice of Disclosure. Neither party may disclose any Confidential
Information of the other party to any third party, including any other PDC
member, without prior written approval of the party disclosing such
Confidential Information. Should a party be obliged by an authoritative
governmental body to make a disclosure to it of the other party's Confidential
Information, the party will give reasonable advance notice of such legal
obligation to the party who provided such Information and will use its best
efforts, and permit intervention of the disclosing party, to secure
confidential treatment of such Information (whether through protective order or
other means) prior to its disclosure to such governmental body, and such
disclosure shall be limited to Information necessary to comply with such legal
obligations.

8.4     Limitation on Use of Confidential Information by Affiliates. Member
shall not provide Argonaut's Confidential Information to any Affiliate Member
whose significant business is in the selling or commercialization of
instruments for the purpose of automating chemical process development.
Argonaut shall not provide Member's Confidential Information to any Affiliate
of Argonaut whose significant business is in the discovery or development of
drug compounds or in the production of chemical libraries of compounds useful
for such purposes.

                                       9
                       CONSIDERATION AND PURCHASE CREDITS

9.1     Payment to Argonaut. In consideration for its participation in the PDC,
Member shall pay to Argonaut a total of Seventy Thousand U.S. Dollars ($70,000),
in two installments. The first installment of $50,000 shall be due and payable
thirty (30) days after the execution of this Agreement, and the second
installment of $20,000 shall be due and payable on or before July 15, 1999. Such
payment shall be non-refundable except as set forth below.

9.2     Priority. Argonaut shall notify each PDC member of the date of
commercial release of Instruments and the commercial, non-academic list price
of such Instruments. In consideration for its participation in the PDC, and
provided that Member timely pays Argonaut the amounts set forth in Section 9.1,
Member will receive priority status with regard to the purchase of Instruments
from Argonaut as they become available for delivery. Priority among Member and
other PDC members will be based on the order of receipt of purchase orders from
Member or such other PDC members. Notwithstanding the above, in the event that
Argonaut receives purchase orders for multiple Instruments from two or more PDC
members within any ninety (90) day period, Argonaut will


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<PAGE>   7
prorate deliveries of Instruments among such members based on the relative size
of such orders, but no member of the PDC shall receive a second Instrument
before other PDC members who order one or more Instruments within the ninety
(90) day period shall receive their first Instrument.

9.3  Credit. Member will be entitled to a credit equal to the amount of the
payments actually made to Argonaut as set forth in section 9.1 (the "Credit"),
applicable toward the purchase of one or more Instruments at a price no higher
than the commercial, non-academic list price established and published by
Argonaut (the "List Price"). Any unused portion of the Credit shall expire one
(1) year after the date of commercial release of Instruments.

9.4  Refund. If Argonaut fails to deliver an Instrument to Member by December
31, 2000, Argonaut agrees to refund to Member the payments made by Member to
Argonaut. If Member elects to terminate this Agreement under Section 11.3.1,
Member shall retain the right to the Credit under Section 9.3 above applicable
toward the purchase of one or more Instruments at the List Price.

                                       10
                             DISCLAIMER OF WARRANTY

10.1 Disclaimer of Warranty. Argonaut expressly disclaims any warranty that the
PDC will lead to or result in the creation of a Prototype or Instrument meeting
Member's requirements or that the PDC will otherwise meet Member's
expectations, or that any Prototypes or Instruments will be error-free or free
from non-correctable defects.

EXCEPT AS EXPRESSLY SET FORTH ELSEWHERE IN THIS AGREEMENT, ARGONAUT DISCLAIMS
ALL WARRANTIES RELATING TO THE PDC OR ANY PROTOTYPES OR INSTRUMENTS, EXPRESS OR
IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE OR THAT THE PROTOTYPES OR
INSTRUMENTS WILL NOT INFRINGE ANY THIRD PARTY INTELLECTUAL PROPERTY RIGHTS.

10.2 Infringement Notice and Indemnification. Each PDC member shall promptly
notify every other PDC member if it becomes aware that any Prototype or
Instrument directly infringes, contributory infringes or induces the
infringement of any third party's intellectual property rights or raises a
substantial question thereof. Argonaut shall defend and indemnify Member
harmless for any loss, damage or expense arising from any third-party claim of
infringement or other intellectual property right based on Member's use of any
Instrument purchased by Member from Argonaut under this Agreement, or any
hardware or software components thereof.

10.3 Assumption of Risk. Each PDC member understands that any Prototype and
Information provided hereunder may be experimental in nature, and hereby
expressly assumes all liability for any personal injury, death, loss of profit,
and/or property damage arising out of or in connection with such PDC member's
participation in the PDC or the use of any Prototype or any Information under
this Agreement, unless due to the negligence or misconduct of Argonaut.

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                                       11
                              TERM AND TERMINATION

11.1  Term. This Agreement and the PDC shall terminate upon the commercial
release of the Instrument, unless terminated: (i) earlier as provided in this
Article 11; or (ii) extended due to the fact that the testing period for a
Prototype or replacement Prototype has not yet expired and for the time
necessary to complete such testing period.

11.2  Termination for Material Breach. Either party has the right to terminate
this Agreement for a material breach of this Agreement, provided the breaching
party fails to take reasonable steps towards the remedy of such breach within
sixty (60) days of receipt of written notice of the material breach from the
non-breaching party. In the event of termination by Member under this Section
for material breach by Argonaut, Member shall be entitled to a refund of any
payments made to Argonaut under Section 9.1.

11.3  Permissive Termination.

      11.3.1  Member. Member may terminate this Agreement effective at any time
prior to the second consortium meeting, by providing Argonaut with written
notice of its intention to terminate. In such event, Argonaut shall return the
first installment payment of $50,000 to Member, and Member shall have no
obligation to pay to Argonaut the installment payment due July 15, 1999.

      11.3.2  Argonaut. Argonaut may terminate this Agreement at any time on
sixty (60) days' notice, if at any time there are fewer than seven (7) members
of the PDC other than Argonaut. Argonaut will in such event return to Member all
funds received by Argonaut from Member.

11.4  Effect of Termination. Upon any termination of this Agreement, each party
shall return to the other any Confidential Information received form the other
party (except one copy that may be retained solely for legal archival purposes).

11.5  Survival. Section 6.1 and Articles 1, 7, 8, 9, 10, 11 and 12 of this
Agreement shall survive the termination of expiration of this Agreement for any
reason.

                                       12
                               GENERAL PROVISIONS

12.1  Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the State of California, without reference to
principles of conflicts of laws.

12.2  Independent Contractors. The relationship of the parties hereto is that of
independent contractors. The parties are not deemed to be agents, partners or
joint venturers of the others for any purpose as a result of this Agreement or
the transactions contemplated thereby. Member and

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<PAGE>   9


Argonaut shall have no power to make any commitment binding upon the other party
unless authorized in writing in advance in each particular instance.

12.3 Compliance with Laws. In exercising their rights under this Agreement, the
parties shall fully comply with the requirements of any and all applicable laws,
regulations, rules and orders of any governmental body having jurisdiction over
the exercise of rights under this Agreement.

12.4 Force Majeure. Nonperformance of any party shall be excused to the extent
that performance is rendered impossible by strike, fire, earthquake, flood,
governmental acts or orders or restrictions, failure of suppliers, or any other
reason where failure to perform is beyond the reasonable control and not caused
by the negligence, intentional conduct or misconduct of the nonperforming party.

12.5 No Consequential Damages. IN NO EVENT SHALL ANY PARTY HERETO BE LIABLE FOR
SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT OR
THE EXERCISE OF RIGHTS HEREUNDER, HOWEVER CAUSED, UNDER ANY THEORY OF LIABILITY.

12.6 Notices. All notices, requests and other communications hereunder shall be
in writing and shall be personally delivered or sent by telecopy or other
electronic facsimile transmission or by registered, certified, or express mail,
or by commercial overnight delivery service, return receipt requested, postage
prepaid, in each case to the respective address specified below, or such other
address as may be specified in writing to the other parties hereto in accordance
with this Section 12.6:

      If to Argonaut:         Argonaut Technologies, Inc.
                              887 Industrial Road, Suite G
                              San Carlos, California 94070
                              Attn: Elizabeth M. Mitchell
                              Telephone: (650) 598-1350
                              Facsimile: (650) 598-1359


      If to Member:           Gary E. Friedman, Esq.
                              Agouron Pharmaceuticals, Inc.
                              10350 North Torrey Pines Road
                              La Jolla, CA 92037-1020
                              Telephone: (619) 622-3140
                              Facsimile: (619) 622-3297


                              with a cc to: Van Martin, Ph.D.
                              Agouron Pharmaceuticals, Inc.
                              10350 North Torrey Pines Road
                              La Jolla, CA 92037-1020




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<PAGE>   10
12.7    Assignment. Either party may assign this Agreement with the written
consent of the other party, which consent shall not be unreasonably withheld.
Either party may assign this Agreement to an entity that acquires all or
substantially all of the business or assets of such party to which this
Agreement pertains, whether by merger, reorganization, acquisition, sale, or
otherwise. This Agreement shall be binding upon and inure to the benefit of the
successors and permitted assigns of the parties.

12.8    Agreement to Perform Necessary Acts. At either party's request, each
party agrees to perform any further acts and execute and deliver all further
documents, agreements and/or instruments which may be reasonably necessary or
desirable to carry out or effect the provisions of this Agreement, including,
but not limited to, the execution of assignment documents pertaining to Patents
pursuant to the provisions of Article 7.

12.9    Further Agreements. Member and Argonaut may enter into further
agreements with respect to the particular matters outside the scope of this
Agreement, on agreed terms.

12.10   Severability. In the event that any provision of this Agreement becomes
or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision. In such a situation the parties shall promptly
negotiate in good faith with respect to amendments to such provision of this
Agreement that may be necessary to make it fair and equitable to the parties.

12.11   Waiver. Neither party may waive or release any of its rights or
interests in this Agreement except in writing. The failure of either party to
assert a right hereunder or to insist upon compliance with any term or
condition of this Agreement shall not constitute a waiver of that right or
excuse a similar subsequent failure to perform any such term or condition.

12.12   Headings. The captions to the several Sections and Articles hereof are
not a part of this Agreement, but are included merely for convenience of
reference only and shall not affect its meaning or interpretation.

12.13   Complete Agreement. This Agreement constitutes the entire agreement,
both written and oral, between the parties with respect to the subject matter
hereof. All prior agreements respecting the subject matter hereof, either
written or oral, expressed or implied, are merged and canceled, and are null
and void and of no effect. No amendment or change hereof or addition hereto
shall be effective or binding on either of the parties hereto unless reduced to
writing and executed by the respective duly authorized representatives of
Member and Argonaut.

12.14   Counterparts. This Agreement may be executed in counterparts, each of
which shall be deemed to be an original, and both together shall be deemed to
be one and the same agreement.

        IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by its duly authorized officers.

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AGOURON PHARMACEUTICALS, INC.           ARGONAUT TECHNOLOGIES, INC.

BY: D. Frederick Jay                    BY: Mark W. Schwartz, Ph.D.
TITLE: Associate General Counsel        TITLE: Vice President, Business
                                               Development and Marketing

SIGNATURE: /s/ D. FREDERICK JAY         SIGNATURE: /s/ MARK W. SCHWARTZ
           ------------------------                -----------------------------

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                                   EXHIBIT A

                                      [*]



[*] Confidential Treatment Requested

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                                      [*]



[*] Confidential Treatment Requested

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