<PAGE>   1
                                                                   Exhibit 10.33

LESSOR:                                                         MASTER EQUIPMENT
JULES AND ASSOCIATES, INC.                                       LEASE AGREEMENT
515 SOUTH FIGUEROA STREET
SUITE 1950
LOS ANGELES, CA  90071

                                            MASTER LEASE AGREEMENT NO. A10161999

   Lease Agreement made this 23rd day of November, 1999 between JULES AND
ASSOCIATES, INC. ("Lessor") with a place of business located at 515 South
Figueroa Street, Suite 1950, Los Angeles, California 90071 and PharmChem
Laboratories, Inc. ("Lessee") having its principal place of business located at
1505-A O'Brien Drive, Menlo Park, California 94025-1435.

   1. LEASE AGREEMENT. Lessor hereby leases to Lessee and Lessee hereby leases
from Lessor all of the personal property ("Equipment") described in Equipment
Lease Schedule(s), which are or may from time to time be executed by Lessor and
Lessee and attached hereto or incorporated herein by reference ("Schedules"),
upon the terms and conditions set forth in this Lease, as supplemented by the
terms and conditions set forth in the appropriate Schedule(s) identifying such
items of Equipment. All terms and conditions of this Lease shall govern the
rights and obligations of Lessor and Lessee except as specifically modified in
writing. Whenever reference is made herein to the "Lease", it shall be deemed to
include each of the various Schedules identifying all items of Equipment, all of
which constitute one undivided Lease of the Equipment and the terms and
conditions of which are incorporated herein by reference. Lessee's liability for
Lessee's obligations under this Lease will survive the expiration or earlier
termination of this Lease.

   2. SELECTION OF EQUIPMENT; ACCEPTANCE. Lessee will select the type, quantity
and supplier of each item of Equipment designated in the appropriate Schedule,
and in reliance thereon such Equipment will then be ordered by Lessor from such
supplier or Lessor will accept an assignment of any existing purchase order
therefore. Lessor will have no liability for any delivery or failure by the
supplier to fill the purchase order or to meet the conditions thereof. Lessee
acknowledges that Lessor has not participated and will not participate in any
way in Lessee's selection of the Equipment or of the supplier. Lessee agrees to
inspect the Equipment and to execute an Acknowledgment and Acceptance of
Equipment by Lessee notice, as provided by Lessor, after the Equipment has been
delivered and after Lessee is satisfied that the Equipment is satisfactory in
every respect. Lessee hereby authorizes Lessor to insert in this Lease serial
numbers or other identifying data with respect to the Equipment.

   3. DISCLAIMER OF WARRANTIES AND CLAIMS; LIMITATION OF REMEDIES. LESSOR, NOT
BEING THE MANUFACTURER OF THE EQUIPMENT NOR THE MANUFACTURER'S AGENT, MAKES NO
EXPRESS OR IMPLIED WARRANTY OF ANY KIND WHATSOEVER WITH RESPECT TO THE
EQUIPMENT, INCLUDING, BUT NOT LIMITED TO, THE MERCHANTIBILITY OF THE EQUIPMENT
OR ITS FITNESS FOR ANY PARTICULAR PURPOSE; THE DESIGN OR CONDITION OF THE
EQUIPMENT; THE QUALITY OR CAPACITY OF THE EQUIPMENT; THE WORKMANSHIP IN THE
EQUIPMENT; COMPLIANCE OF THE EQUIPMENT WITH THE REQUIREMENT OF ANY LAW, RULE,
SPECIFICATION OR CONTRACT PERTAINING THERETO; PATENT INFRINGEMENT; OR LATENT
DEFECTS. LESSEE LEASES THE EQUIPMENT "AS IS" AND WITH ALL FAULTS. LESSEE
ACCORDINGLY AGREES NOT TO ASSERT ANY CLAIM WHATSOEVER AGAINST LESSOR FOR LOSS OF
ANTICIPATORY PROFITS OR CONSEQUENTIAL DAMAGES. LESSOR SHALL HAVE NO OBLIGATION
TO INSTALL, ERECT, TEST, SERVICE, OR MAINTAIN THE EQUIPMENT. LESSEE SHALL LOOK
TO THE MANUFACTURER AND/OR SELLER FOR ANY CLAIMS RELATED TO THE EQUIPMENT.

   IF THE EQUIPMENT IS NOT PROPERLY INSTALLED, DOES NOT OPERATE AS REPRESENTED
OR WARRANTED BY THE SUPPLIER OR MANUFACTURER, OR IS UNSATISFACTORY FOR ANY
REASON, REGARDLESS OF CAUSE OR CONSEQUENCE, LESSEE'S ONLY REMEDY, IF ANY, SHALL
BE AGAINST THE SUPPLIER OR MANUFACTURER OF THE EQUIPMENT AND NOT AGAINST LESSOR.

   LESSOR HEREBY ACKNOWLEDGES THAT ANY MANUFACTURER'S AND/OR SELLER'S WARRANTIES
ARE FOR THE BENEFIT OF BOTH LESSOR AND LESSEE. NOTWITHSTANDING THE FOREGOING,
LESSEE'S OBLIGATIONS TO PAY THE RENTALS OR OTHERWISE UNDER THIS LEASE SHALL BE
AND ARE ABSOLUTE AND UNCONDITIONAL. TO THE EXTENT PERMITTED BY THE MANUFACTURER
OR SELLER, AND PROVIDED LESSEE IS NOT IN DEFAULT UNDER THIS LEASE, LESSOR SHALL
MAKE AVAILABLE TO LESSEE ALL MANUFACTURER AND/OR SELLER WARRANTIES WITH RESPECT
TO EQUIPMENT.

   LESSEE SPECIFICALLY ACKNOWLEDGES THAT THE EQUIPMENT IS LEASED TO LESSEE
SOLELY FOR COMMERCIAL OR BUSINESS PURPOSES AND NOT FOR PERSONAL, FAMILY,
HOUSEHOLD, OR AGRICULTURAL PURPOSES.

THE PARTIES HAVE SPECIFICALLY NEGOTIATED AND AGREED TO THE FOREGOING PARAGRAPH:
LESSEE INITIALS: S/ DAL .


/S/  DAL

                                   PAGE 1 OF 5

<PAGE>   2
   4. STATUTORY FINANCE LEASE. Lessee agrees and acknowledges that it is the
intent of both parties to this Lease that it qualify as a statutory finance
lease under Article 2A of the Uniform Commercial Code. Lessee acknowledges and
agrees that Lessee has selected both: (1) the Equipment; and (2) the supplier
from whom Lessor is to purchase the Equipment. Lessee acknowledges that Lessor
has not participated in any way in Lessee's selection of the Equipment or of the
supplier, and Lessor has not selected, manufactured, or supplied the Equipment.

   LESSEE IS ADVISED THAT IT MAY HAVE RIGHTS UNDER THE CONTRACT EVIDENCING THE
LESSOR'S PURCHASE OF THE EQUIPMENT FROM THE SUPPLIER CHOSEN BY LESSEE AND THAT
LESSEE SHOULD CONTACT THE SUPPLIER OF THE EQUIPMENT FOR A DESCRIPTION OF ANY
SUCH RIGHTS.

   5. ASSIGNMENT BY LESSEE PROHIBITED. WITHOUT LESSOR'S PRIOR WRITTEN CONSENT,
LESSEE SHALL NOT ASSIGN THIS LEASE OR SUBLEASE THE EQUIPMENT OR ANY INTEREST
THEREIN, OR PLEDGE OR TRANSFER THIS LEASE, OR OTHERWISE DISPOSE OF THE EQUIPMENT
COVERED HEREBY.

   6. COMMENCEMENT; RENTAL PAYMENTS; INTERIM RENTALS. This Lease shall commence
upon the written acceptance hereof by Lessor and shall end upon full performance
and observance by Lessee of each and every term, condition and covenant set
forth in this Lease, any Schedules hereto and any extensions hereof. The monthly
rental payments shall be in advance and shall be in the amounts and frequency as
set forth on the face of this Lease or any Schedules hereto. The first such
rental payment shall be made on the first day of the month following the date on
which the Equipment is accepted by the Lessee. In addition to regular rentals,
Lessee shall pay to Lessor interim rent, which shall be a pro-rata portion of
the monthly rental charges based on a daily rental charge of one-thirtieth
(1/30th) of the monthly rental calculated from the date on which the Equipment
is accepted by the Lessee to the end of the respective month, and shall be due
and payable upon Lessee's receipt of invoice from Lessor. The rental period
under the Lease shall terminate following the last day of the terms stated on
the face hereof or in any Schedule hereto unless such Lease or Schedule has been
extended or otherwise modified. Lessor shall have no obligation to Lessee under
this Lease if the Equipment, for whatever reason, is not delivered to Lessee
within ninety (90) days after Lessee signs this Lease. Lessor shall have no
obligation to Lessee under this Lease if Lessee fails to execute and deliver to
Lessor an Acknowledgment and Acceptance of Equipment by Lessee acknowledging its
acceptance of the Equipment within thirty (30) days after it is delivered to
Lessee, with respect to this Lease or any Schedule hereto.

   7. SECURITY DEPOSIT. As security for the prompt and full payment of rent, and
the faithful and timely performance of all provisions of this Lease, and any
extensions or renewals thereof, Lessee shall pledge and deposit with Lessor the
security amount set forth in the section shown as "Security Deposit" on each
respective Schedule. In the event any default shall be made in the performance
of any of Lessee's obligations under this Lease, Lessor shall have the right,
but shall not be obligated, to apply said security to the curing of such
default. Within 15 days after Lessor mails notice to Lessee that Lessor has
applied any portion of the Security Deposit to the curing of any default, Lessee
shall restore said Security Deposit to the full amount set forth in the
Schedules. On the expiration or earlier termination of each Schedule to this
Lease, or any extension or renewal thereof, provided Lessee has paid all of the
rent herein called for and fully performed all other provisions of this Lease
with respect to such Schedule, Lessor will return to Lessee any then remaining
balance of the security deposit with respect to such Schedule, without interest.
Said security deposit may be commingled with Lessor's other funds.

   8. LIMITED PREARRANGED AMENDMENTS. SPECIFIC POWER OF ATTORNEY; In the event
it is necessary to amend the terms of this Lease or the terms of any Schedule to
reflect a change in one or more of the following conditions:

   (1) Lessor's actual cost of procuring the Equipment; or
   (2) Lessor's actual cost of providing Equipment to Lessee; or
   (3) A change in the Lease payments as a result of (1) and/or (2) above; or
   (4) Description of the leased Equipment,

Lessee agrees that any such amendment shall be described in a letter from Lessor
to Lessee, and unless within 15 days after the date of such letter Lessee
objects thereto in a writing delivered to Lessor, this Lease and any affected
Schedules shall be deemed amended and such amendments shall be incorporated
herein/therein as if originally set forth herein/therein. Lessee grants to
Lessor a specific power of attorney for Lessor to use as follows: (1) Lessor may
sign and file on Lessee's behalf any document Lessor deems necessary to perfect
or protect Lessor's interest in the Equipment or pursuant to the Uniform
Commercial Code; and (2) Lessor may sign, endorse or negotiate for Lessor's
benefit any instrument representing proceeds from any policy of insurance
covering the Equipment.


/S/  DAL


                                   PAGE 2 OF 5

<PAGE>   3
   9. LOCATION. The Equipment shall be kept at the location specified in each
Schedule or, if none is specified, at Lessee's address as set forth above, and
shall not be removed therefrom without Lessor's prior written consent. Lessor
shall have the right to inspect the Equipment and observe its use during normal
business hours, and Lessee will ensure Lessor's ability to enter into and upon
the premises where the Equipment may be located for such purpose.

   10. USE. Lessee shall use the Equipment in a careful manner, shall make all
necessary repairs at Lessee's expense, and shall comply with all laws relating
to its possession, use or maintenance, and shall not make any alterations,
additions or improvements to the Equipment without Lessor's prior written
consent. All additions, repairs or improvements made to the Equipment shall
belong to Lessor.

   11. OWNERSHIP; PERSONALITY. The Equipment is, and shall remain, the property
of Lessor, and Lessee shall have no right, title or interest therein or thereto
except as expressly set forth in this Lease. Should Lessee have an end of term
purchase option and Lessee does not give proper notice as agreed upon by both
parties, then, that purchase option shall be null and void and the terms and
conditions as set forth in this Agreement shall prevail after any extension
period. The Equipment shall remain personal property even though installed in or
attached to real property.

   12. SURRENDER. By this Lease, Lessee acquires no ownership rights in the
Equipment and has no option to purchase same. Upon the expiration or termination
of any Schedule or this Lease, or in the event of a default pursuant to
Paragraph 20 hereof, Lessee, at its expense, shall return the Equipment in good
repair, ordinary wear and tear resulting from proper use thereof alone excepted,
by delivering it, packed and ready for shipment, to such place or carrier as
Lessor may specify.

   13. RENEWAL. At the expiration of the term set forth in each Schedule, Lessee
shall return the Equipment subject to said Schedule in accordance with Paragraph
12 hereof. At Lessor's option, this Lease, with respect to each Schedule, may be
continued on a month-to-month basis until 30 days after Lessee returns the
Equipment subject to the Schedule to Lessor. In the event that the Lease, with
respect to a Schedule, is so continued, Lessee shall pay to Lessor rentals in
the same periodic amounts as indicated under "Rental" on the Schedule.

   14. LOSS AND DAMAGE. Lessee shall bear the entire risk of loss, theft, damage
or destruction of the Equipment from any cause whatsoever, and no loss, theft,
damage or destruction of the Equipment shall relieve Lessee of the obligation to
pay rent or to comply with any other obligation under this Lease.
In the event of damage to any item of Equipment, Lessee shall immediately place
the same in good repair at Lessee's expense. If Lessor determines that any item
of Equipment is lost, stolen, destroyed or damaged beyond repair, Lessee shall
at Lessee's option do one of the following:

   (a) Replace the same with like Equipment in good repair, acceptable to
       Lessor; or

   (b) Pay Lessor in cash the following: (i) all amounts due by Lessee to Lessor
       with respect to all affected Schedules up to the date of the loss; (ii)
       the unpaid balance of the total rent for the remaining term of the
       affected Schedules attributable to said item, reduced to present value at
       a discount rate of 6% as of the date of the loss; and (iii) the Lessor's
       estimate as of the time this Lease was entered into of Lessor's residual
       interest in the Equipment, discounted to present value at a discount rate
       of 6% as of the date of the loss. Upon Lessor's receipt of payment as set
       forth above, Lessee shall be entitled to the Equipment, without any
       warranties. If insurance proceeds are used to fully comply with this
       subparagraph, the balance of any such proceeds shall go to Lessee to
       compensate for loss of use of the Equipment for the remaining term of the
       Lease.

   15. INSURANCE; LIENS; TAXES. Lessee shall provide and maintain insurance
against loss, theft, damage or destruction of the Equipment in an amount not
less than the full replacement value of the Equipment, with loss payable to
Lessor. Lessee shall also provide and maintain comprehensive general all-risk
liability insurance, including but not limited to product liability coverage,
insuring Lessor and Lessee with a severability of interest endorsement or its
equivalent, against any and all loss or liability for damages either to persons
or property or otherwise, which might result from or happen in connection with
the condition, use or operation of the Equipment, with such limits and with an
insurer as are satisfactory to Lessor. Each policy shall expressly provide that
said insurance as to Lessor and its assigns shall not be invalidated by any act,
omission or neglect of Lessee and cannot be canceled without 30 days written
notice to Lessor. As to each policy, Lessee shall furnish to Lessor a
certificate of insurance from the insurer, which certificate shall evidence the
insurance coverage required by this Paragraph and shall designate Lessor as loss
payee and/or additional insured. Lessor shall have no obligation to ascertain
the existence or adequacy of insurance, or to provide any insurance coverage for
the Equipment or for Lessee's benefit.

   Lessee shall keep the Equipment free and clear of all levies, liens and
encumbrances. Lessee shall pay all charges and taxes (local, state and federal)
which may now or hereafter be imposed upon the ownership, leasing, rental, sale,
purchase, possession or use of the Equipment excluding, however, all taxes on or
measured by Lessor's net income.

   If Lessee fails to procure or maintain said insurance or to pay said charges
or taxes, Lessor shall have the right, but shall not be obligated, to effect
such insurance, or pay such charges or taxes. In that event, Lessor shall notify
Lessee of such payment and Lessee shall repay to Lessor the cost thereof within
15 days after such notice is mailed to Lessee.

/S/  DAL
                                   PAGE 3 OF 5
<PAGE>   4
   16. INDEMNITY. Lessee shall indemnify Lessor against any claims, actions,
damages or liabilities, including all attorney fees, arising out of or connected
with the Equipment, without limitation. Such indemnification shall survive the
expiration, cancellation or termination of this Lease. Lessee waives any
immunity Lessee may have under any industrial insurance act with regard to
indemnification of Lessor.

   17. ASSIGNMENT BY LESSOR. Any assignee of Lessor shall have all of the rights
but none of the obligations of Lessor under this Lease. Lessee shall recognize
and hereby consents to any assignment of this Lease by Lessor, and Lessee shall
not assert against the assignee any defense, counterclaim or set-off that Lessee
may have against Lessor. Subject to the foregoing, this Lease inures to the
benefit of and is binding upon the heirs, devisees, personal representatives,
survivors, successors in interest and assigns of the parties hereto.

   18. SERVICE CHARGES; INTEREST. If Lessee shall fail to make any payment
required by this Lease within 10 days of the due date thereof, Lessee shall pay
to Lessor a service charge of 8% of the amount due, provided, however, that not
more than one such service charge shall be made on any delinquent payment
regardless of the length of the delinquency. In addition to the foregoing
service charge, Lessee shall pay to Lessor a $100 default fee with respect to
any payment which becomes thirty (30) days past due. In addition, Lessee shall
pay to Lessor any actual additional expenses incurred by Lessor in collection
efforts, including but not limited to long-distance telephone charges and travel
expenses.

   Further, Lessee shall pay to Lessor interest on any delinquent payment or
amount due under this Lease from the due date thereof until paid, at the lesser
of the maximum rate of interest allowed by law or 18% per annum.

   19. TIME OF ESSENCE. Time is of the essence of this Lease, and this provision
shall not be impliedly waived by the acceptance on occasion of late or defective
performance.

   20. DEFAULT. Lessee shall be in default of this Lease if:

   (a) Lessee shall fail to make any payment due under the terms of this Lease
for a period of 10 days from the due date thereof; or

   (b) Lessee shall fail to observe, keep or perform any other provision of this
Lease, and such failure shall continue for a period of 10 days; or

   (c) Lessee has made any misleading or false statement in connection with
application for or performance of this Lease; or

   (d) The Equipment or any part thereof shall be subject to any lien, levy,
seizure, assignment, transfer, bulk transfer, encumbrance, application,
attachment, execution, sublease, or sale without prior written consent of
Lessor, or if Lessee shall abandon the Equipment or permit any other entity or
person to use the Equipment without prior written consent of Lessor; or

   (e) Lessee dies or ceases to exist or ceases business activities; or

   (f) Lessee defaults on any other agreement it has with Lessor; or

   (g) Lessee or any guarantor of this Lease defaults on any obligation to
Lessor, or any to the above-listed events of default occur with respect to
Lessee or any guarantor, or Lessee or any such guarantor files or has filed
against it a petition under the bankruptcy laws; or

   (h) Lessee undergoes a sale, buyout, change of control, or change in
ownership of any type, form or manner which, as judged solely by Lessor, results
in deterioration in Lessee's credit worthiness.

   21. REMEDIES. If Lessee is in default, Lessor, with or without notice to
Lessee, shall have the right to exercise any one or more of the following
remedies, concurrently or separately and without any election of remedies being
deemed to have been made:

   (a) Lessor may enter upon Lessee's premises and without any court order or
other process of law may repossess and remove the Equipment, or render the
Equipment unusable without removal, either with or without notice to Lessee.
Lessee hereby waives any trespass or right of action for damages by reason of
such entry, removal or disabling. Any such repossession shall not constitute a
termination of this Lease;

   (b) Lessor may require Lessee, at its expense, to return the Equipment in
good repair, ordinary wear and tear resulting from proper use thereof alone
excepted, by delivering it, packed and ready for shipment, to such place or
carrier as Lessor may specify;

   (c) Lessor may cancel or terminate this Lease and may retain any and all
prior payments paid by Lessee;

   (d) Lessor may declare all sums due and to become due under this Lease
immediately due and payable, including as to any or all items of Equipment,
without notice or demand to Lessee;

   (e) Lessor may re-release the Equipment to any third party, without notice to
Lessee, upon such terms and conditions as Lessor alone shall determine, or may
sell the Equipment without notice to Lessee, at private or public sale, at which
sale Lessor may be the purchaser;

   (f) Lessor may sue for and recover from Lessee the sum of all unpaid rents
and other payments due under this Lease then accrued, plus all accelerated
future payments due under this Lease, reduced to their present value using a
discount rate of 6%, as of the date of default, plus Lessor's estimate at the
time this Lease was entered into of Lessor's residual interest in
the Equipment, reduced to present value at a discount rate of 6%, as of the
date of default, less the net proceeds of disposition, if any, of the Equipment;


/S/  DAL
                                   PAGE 4 OF 5

<PAGE>   5
   (g) To pursue any other remedy available at law, by statute or in equity.

No right or remedy conferred upon or reserved to Lessor is exclusive of any
other right or remedy herein, or by law or by equity provided or permitted, but
each shall be cumulative of every other right or remedy given herein or now or
hereafter existing by law or equity or by statute or otherwise, and may be
enforced concurrently therewith or from time to time. No single or partial
exercise by Lessor of any right or remedy hereunder shall preclude any other or
further exercise of any other right or remedy.

   22. MULTIPLE LESSEES. Lessee and each of them are jointly and severally
responsible and liable to Lessor under this Lease. Lessor may, with the consent
of any one of the Lessees hereunder, modify, extend or change any of the terms
hereof without consent or knowledge of the others, without in any way releasing,
waiving or impairing any right granted to Lessor against the others.

   23. EXPENSE OF ENFORCEMENT. In the event of any legal action with respect to
this Lease, the prevailing party in any such action shall be entitled to
reasonable attorney fees, including attorney fees incurred at the trial level,
including action in bankruptcy court, on appeal or review, or incurred without
action, suits or proceedings, together with all costs and expenses incurred in
pursuit thereof.

   24. MISCELLANEOUS.

(1) LESSEE HEREBY ACKNOWLEDGES THAT THIS LEASE IS NONCANCELABLE FOR THE ORIGINAL
RENTAL TERM SET FORTH IN EACH SCHEDULE.
(2) LESSEE UNDERSTANDS AND ACKNOWLEDGES THAT NO BROKER OR SUPPLIER NOR ANY
SALESMAN, BROKER OR AGENT OF ANY BROKER OR SUPPLIER IS AN AGENT OF LESSOR. NO
BROKER OR SUPPLIER, NOR ANY SALESMAN, BROKER OR AGENT OF ANY BROKER OR SUPPLIER
IS AUTHORIZED TO WAIVE OR ALTER ANY TERM OR CONDITION OF THIS LEASE, AND NO
REPRESENTATION AS TO THE EQUIPMENT OR ANY OTHER MATTER BY A BROKER OR SUPPLIER
OR ANY SALESMAN, BROKER OR AGENT OF ANY BROKER OR SUPPLIER SHALL IN ANY WAY
AFFECT LESSEE'S DUTY TO PAY THE RENTALS AND TO PERFORM LESSEE'S OBLIGATIONS SET
FORTH IN THIS LEASE. LESSEE AUTHORIZES LESSOR TO INSERT ANY APPLICABLE DATES ON
THE LEASE OR ATTACHMENTS TO THE LEASE.
(3) LESSEE AGREES THAT LESSOR MAY USE LESSEE'S NAME IN ADVERTISING AND
PROMOTIONAL MATERIALS AND GENERAL TERMS OF THIS MASTER EQUIPMENT LEASE AND
SCHEDULES.
(4) LESSEE SHALL FURNISH LESSOR WITH (a) A FISCAL YEAR END FINANCIAL STATEMENT
INCLUDING BALANCE SHEET AND INCOME STATEMENT WITHIN ONE HUNDRED AND TWENTY DAYS
(120) DAYS OF THE CLOSE OF EACH FISCAL YEAR AND (b) SUCH OTHER FINANCIAL DATA OR
INFORMATION RELATIVE TO THIS LEASE AND THE EQUIPMENT AS LESSOR MAY FROM TIME TO
TIME REQUEST.

   25. SEVERABILITY. This Lease is intended to constitute a valid and
enforceable legal instrument. In the event any provision hereof is declared
invalid, such provision will be deemed severable from the remaining provisions
of this Lease, all of which will remain in full force and effect.

   26. ENTIRE AGREEMENT; WAIVER. This instrument and the Schedules executed by
Lessor and Lessee constitute the entire agreement between Lessor and Lessee with
respect to the Equipment and the subject matter of this Lease. Lessee certifies
and warrants that this Lease has been duly authorized, executed and delivered by
Lessee and constitutes the legal, valid and binding obligation and that the
person executing this Lease on behalf of the Lessee warrants that he or she has
been authorized to do so. No provision of this Lease shall be modified unless in
writing signed by an authorized representative of Lessor and Lessee. Waiver by
Lessor of any provision hereof in one instance shall not constitute a waiver of
any other instance. NO ORAL OR WRITTEN AGREEMENT, GUARANTY, PROMISE, CONDITION,
REPRESENTATION OR WARRANTY SHALL BE BINDING UNLESS MADE A PART OF THIS LEASE BY
DULY EXECUTED ADDENDUM.

                          LESSOR INITIALS: /S/ JB     LESSEE INITIALS: /S/  DAL
                                           ------                      --------

   27. CHOICE OF LAW; JURISDICTION. THIS LEASE SHALL NOT BE EFFECTIVE UNTIL
SIGNED BY LESSOR AT ITS PRINCIPAL PLACE OF BUSINESS LISTED ABOVE. THIS LEASE
SHALL BE CONSIDERED TO HAVE BEEN MADE IN THE STATE OF LESSOR'S PRINCIPAL PLACE
OF BUSINESS AND SHALL BE INTERPRETED IN ACCORDANCE WITH THE LAWS AND REGULATIONS
OF THAT STATE.

   LESSEE AGREES TO JURISDICTION IN THE STATE OF LESSOR'S PRINCIPAL PLACE OF
BUSINESS IN ANY ACTION, SUIT OR PROCEEDING ARISING OUT OF THIS LEASE, AND
CONCEDES THAT IT, AND EACH OF THEM, TRANSACTED BUSINESS IN THE SAID STATE BY
ENTERING INTO THIS LEASE. IN THE EVENT OF LEGAL ACTION TO ENFORCE THIS LEASE,
LESSEE AGREES THAT VENUE MAY BE LAID IN COUNTY OF LESSOR'S PRINCIPAL PLACE OF
BUSINESS.

                          LESSOR INITIALS: /S/ JB     LESSEE INITIALS: /S/  DAL
                                           ------                      --------

LESSEE:                                      LESSOR: JULES AND ASSOCIATES, INC.

<TABLE>
<CAPTION>

<S>                      <C>                    <C>                     <C>
/s/ David A. Lattanzio   Date:  11/23/99        /s/ Jules Buenaventa    Date: 11/29/99
----------------------                          --------------------
David A. Lattanzio, CFO                         Jules Buenaventa, President
MLMM083199
</TABLE>
                                   PAGE 5 OF 5
<PAGE>   6




                                                                  LEASE SCHEDULE


                                                   MASTER EQUIPMENT
                                                   LEASE AGREEMENT NO. A10161999
                                                   LEASE SCHEDULE NO. 1


BETWEEN JULES AND ASSOCIATES, INC. (LESSOR)

and PharmChem Laboratories, Inc. (LESSEE)

1.      DESCRIPTION OF EQUIPMENT
        Quantity             Item                     Model/Serial No.

             "SEE EXHIBIT "A" ATTACHED HERETO AND MADE A PART HEREOF"



2.      EQUIPMENT LOCATION
        The above Equipment is to be located and delivered to Lessee's premises
        at 1505A O'Brien Drive, Menlo Park, CA 94025-1435.

3.      RENTAL TERM:  36 months.

4.      RENTAL PAYMENT:
        The rental payment amount is $38,118.38 with successive rental payments
        in the same amount due on the same day monthly thereafter.

5.      NUMBER AND AMOUNT OF ADVANCE RENTAL PAYMENTS:

        NUMBER:       1           $38,118.38

6.      SECURITY DEPOSIT:    $0.00

7.      THIS SCHEDULE AND ITS TERMS AND CONDITIONS ARE HEREBY INCORPORATED BY
        REFERENCE IN THE ABOVE MASTER EQUIPMENT LEASE AGREEMENT. LESSEE PERMITS
        LESSOR TO INSERT MODEL AND SERIAL NUMBERS OF EQUIPMENT WHEN DETERMINED
        BY LESSOR.

-------------------------------------------------------------------------------

LESSEE:  PharmChem Laboratories, Inc.         LESSOR: JULES AND ASSOCIATES, INC.

(Must be signed by Authorized Corporate
    Officer, Partner, or Proprietor)

/s/ David A. Lattanzio                  /s/ Jules Buenabenta, PRESIDENT
-----------------------------           ---------------------------------------
David A. Lattanzio, CFO                 JULES BUENABENTA

                                        Accepted this 29th day of NOVEMBER 1999
                                        at LOS ANGELES,  CA



<PAGE>   7



                                  ADDENDUM "A"

                                       TO

                 MASTER EQUIPMENT LEASE AGREEMENT NO. A10161999



REFERENCE is made to the above-referenced Mater Equipment Lease Agreement
("Lease") dated the 23rd day of November, 1999, by and between PharmChem
Laboratories, Inc. as Lessee, and Jules and Associates, Inc. as Lessor.

Notwithstanding the terms and conditions contained in the Master Equipment Lease
Agreement and to the limited extent hereof, this superseding anything to the
contrary, the parties hereto agree as follows:

"AFTER THE FINAL RENTAL PAYMENT HAS BEEN MADE SPECIFIC TO THE RESPECTIVE
SCHEDULE, PLUS ALL ACCRUED BUT UNPAID LATE CHARGES, INTEREST, TAXES, PENALTIES
AND/OR ALL OR ANY OTHER SUMS DUE AND OWING UNDER THE LEASE AGREEMENT, AND NO
EVENT OF DEFAULT, AS THE SAME IS MORE FULLY DESCRIBED IN THE LEASE AGREEMENT,
HAS OCCURRED OR IS CONTINUING, AND PROVIDED LESSEE NOTIFIES LESSOR (BY CERTIFIED
MAIL) AT LEAST ONE HUNDRED AND EIGHTY (180) DAYS PRIOR TO FINAL RENTAL PAYMENT
(SPECIFIC TO THE RESPECTIVE SCHEDULE) OF LESSEE'S INTENT OF OPTION CHOICE,
LESSEE MAY EXERCISE ONE OF THE FOLLOWING OTPIONS: 1) PURCHASE ALL OF THE
EQUIPMENT OR PRODUCT FOR THE FAIR MARKET VALUE DETERMINED BY LESSEE; 2) RETURN
ALL OF THE EQUIPMENT OR PRODUCT (AND CEASE USING PRODUCT); 3) EXTEND THE LEASE
FOR AN ADDITIONAL TWELVE MONTH PERIOD AT THE RATE DELINEATED ON THE RESPECTIVE
SCHEDULE. SHOULD LESSEE NOT GIVE PROPER NOTICE AS INDICATED ABOVE, THE LEASE
SHALL BE AUTOMATICALLY EXTENDED FOR AN ADDITIONAL SIX MONTH PERIOD AT THE RATE
DELINEATED ON THE RESPECTIVE SCHEDULE."

In all other respects, the terms and conditions of the Master Equipment Lease
Agreement, as originally set forth, shall remain in full force and effect.

IN WITNESS WHEREOF, the parties hereto, by their authorized signatories, have
executed this Addendum "A" at the date set forth below their respective
signatures.


LESSEE: PHARMCHEM LABORATORIES, INC.        LESSOR: JULES AND ASSOCIATES, INC.


BY      /s/ David A. Lattanzio              BY      /s/ Jules Buenabenta
        --------------------------                  -------------------------
        David A. Lattanzio                          Jules Buenabenta

TITLE   Vice President & CFO                TITLE   President

DATE    November 23, 1999                   DATE    11/29/99


<PAGE>   8




                                  ADDENDUM "B"
                                       TO
                        MASTER EQUIPMENT LEASE AGREEMENT

REFERENCE is made to the above referenced Master Equipment Lease Agreement No.
A10161999, dated November 23, 1999, by and between Pharmchem Laboratories, Inc.
as Lessee and Jules and Associates, Inc., as Lessor.

Notwithstanding the terms and conditions contained in the Master Equipment Lease
Agreement and to the limited extent hereof, this superceding anything to the
contrary, the parties hereto agree as follows:
SECTION 1. LEASE AGREEMENT. Line 2, after the word "Equipment", insert "or
Product" to be consistent with this change the word "Equipment" as it appears
throughout the Master Equipment Lease Agreement is revised to read "Equipment or
Product".

SECTION 6. COMMENCEMENT; RENTAL PAYMENTS; INTERIM RENTALS. Line 5, replace "The
first such rental payment .................. which the Equipment is accepted by
the Lessee" with "The first such rental payment shall be due and payable on the
day that the Equipment is accepted by the Lessee with successive rental payments
in the same amount due on the same day monthly thereafter. Line 6, delete, "In
addition to regular rentals ................... Lessee's receipt of invoice from
Lessor.".

SECTION 12. SURRENDER. At the end of the paragraph, insert "Superceded by the
attached Addendum "A" made a part hereof".

SECTION 13. RENEWAL. At the end of the paragraph, insert "Superceded by the
attached Addendum "A" made a part hereof".

SECTION 15. INSURANCE; LIENS; TAXES. Line 15, after the word "income" insert
"or/and gross revenues".

SECTION 20: DEFAULT: Replace subsection (a) with the following "Lessee shall
fail to make any payment due under the terms of this Lease for a period of ten
(10) days after written notice of such default from Lessor or its assigns."
Replace subsection (b) with the following, "Lessee shall fail to observe, keep
or perform any other provision of this Lease not involving payment of money, and
such failure shall continue for a period of thirty (30) days after written
notice of such default from Lessor or its assigns". Subsection (h) delete "as
judged solely by Lessor".

In all other respects, the terms and conditions of the Master Equipment Lease
Agreement, as originally set forth, shall remain in full force and effect.

In witness hereof, the parties hereto, by their authorized signatories, have
executed this Addendum "B" at the date set forth below by their respective
signatures.

LESSEE: Pharmchem Laboratories, Inc.          LESSOR: Jules and Associates, Inc.

By:      /s/ David A. Lattanzio               By:      /s/ Jules Buenebenta
  -----------------------------                 ---------------------------
Name: David A. Lattanzio                      Name:  Jules Buenabenta
Title: CFO                                    Title: President
Date: November 23, 1999                       Date:  11/29/99