<PAGE>

                                 LOAN AGREEMENT

         THIS LOAN AGREEMENT (the "Agreement"), is entered into as of May 5,
2000, between STRATEGIC DIAGNOSTICS INC., a Delaware corporation (the
"Borrower"), and PNC BANK, DELAWARE (the "Bank").

         Borrower and Bank, with the intent to be legally bound, agree as
follows:

         1. Loan. Bank has made or may make one or more loans including, without
limitation, a $5,000,000 Working Cash(R) line of credit (the "Line of Credit")
and a $4,000,000 term loan (the "Term Loan" and collectively with the Line of
Credit, the "Loan") to Borrower subject to the terms and conditions and upon the
representations and warranties of Borrower set forth in this Agreement. The Loan
is or will be evidenced by a promissory note or notes of Borrower and all
renewals, extensions, amendments and restatements thereof (if one or more,
collectively, the "Note") acceptable to Bank, which shall set forth the
repayment and other provisions, the terms of which are incorporated into this
Agreement by reference.

                  1.1. Borrowing Base. Borrowings under the Line of Credit shall
be limited to a borrowing base, to consist of an amount equal to 85% of Eligible
Accounts (the "Borrowing Base"). "Qualifed Accounts" means those accounts that
are not more than 90 days past due and that are otherwise reasonably acceptable
to Bank, as set forth more fully in the Borrowing Base Rider executed in
connection herewith. Borrower will submit monthly Borrowing Base certificates
within 15 days of each month end, which shall include a detailed listing of
"datings" and a detailed list of all the Accounts of Account Debtor's whose
aggregate amount of Accounts exceed twenty percent (20%) of all of the
Borrower's Accounts.

                  1.2. Interest Rates. The Loan will accrue interest at rates
equal to the one month LIBOR (as defined in the Note) plus the Applicable
Margin. Initially, the Line of Credit shall bear interest at a per annum rate
equal to the one month LIBOR plus 175 basis points and the Term Loan shall bear
interest at a per annum rate equal to the one month LIBOR plus 200 basis points.
Thereafter, the "Applicable Margin" for the Loan will be based upon the ratio of
Funded Debt to EBITDA (as such terms are defined on the Addendum attached
hereto) as measured on a rolling four quarter basis, as set forth on the
Addendum attached hereto. Adjustments, if any, to the Applicable Margin will be
made on the first day of the month immediately following Bank's receipt of
Borrower's quarterly compliance certificate, provided, however, no downward rate
adjustment will be permitted upon the occurrence and continuance of an Event of
Default. In the event Borrower fails to timely deliver such quarterly compliance
certificate, the Applicable Margin shall be the highest Applicable Margin set
forth below until delivery of such compliance certificate.



                                       -1-

<PAGE>

<TABLE>
<CAPTION>

                  Ratio of Funded                    Applicable Margin                  Applicable Margin
                  Debt to EBITDA                     Line of Credit                     Term Loan
                  --------------                     --------------------               --------------------

<S>               <C>                       <C>                                 <C>
                  > 3.0 : 1                          275 basis points                   300 basis points
                  -
                  < 3.0 > 2.75                       250 basis points                   275 basis points
                        -
                  < 2.75 > 2.50                      225 basis points                   250 basis points
                         -
                  < 2.50 > 2.25                      200 basis points                   225 basis points
                         -
                  < 2.25                             175 basis points                   200 basis points
</TABLE>


To protect against fluctuations in a floating rate of interest for the Term
Loan, Borrower at its option may enter into an interest rate protection
agreement with PNC Bank, National Association which conforms to current ISDA
standards and which is otherwise in form and content reasonably satisfactory to
Bank.

         2. Security. The security for repayment of the Loan shall include but
not be limited to the collateral, guaranties, mortgages, assignments of rent and
leases, trademark security agreements, patent security agreements and other
documents, instruments and agreements heretofore, contemporaneously or hereafter
executed and delivered to Bank (the "Security Documents"), which shall secure
repayment of the Loan, the Note and all other loans, advances, debts,
liabilities, obligations, covenants and duties owing by Borrower to Bank or to
any other direct or indirect subsidiary of PNC Bank Corp., of any kind or
nature, present or future (including any interest accruing thereon after
maturity, or after the filing of any petition in bankruptcy, or the commencement
of any insolvency, reorganization or like proceeding relating to Borrower,
whether or not a claim for postfiling or postpetition interest is allowed in
such proceeding), whether or not evidenced by any note, guaranty or other
instrument, whether arising under any agreement, instrument or document, whether
or not for the payment of money, whether arising by reason of an extension of
credit, opening of a letter of credit, loan, equipment lease or guarantee, under
any interest or currency swap, future, option or other interest rate protection
or similar agreement, or in any other manner, whether arising out of overdrafts
on deposit or other accounts or electronic funds transfers (whether through
automated clearing houses or otherwise) or out of Bank's nonreceipt of or
inability to collect funds or otherwise not being made whole in connection with
depository transfer check or other similar arrangements, whether direct or
indirect (including those acquired by assignment or participation), absolute or
contingent, joint or several, due or to become due, now existing or hereafter
arising, and any amendments, extensions, renewals or increases and all costs and
expenses of Bank incurred in the documentation, negotiation, modification,
enforcement, collection or otherwise in connection with any of the foregoing,
including reasonable attorneys' fees and expenses (hereinafter referred to
collectively as the "Obligations"). It is the express intent of Bank and
Borrower that all Obligations including those included in the Loan be
cross-collateralized and cross- defaulted, such that collateral securing any of
the Obligations shall secure repayment of all Obligations and a default or event
of default under any Obligation shall be a default or an event of default under
all Obligations.

         This Agreement, the Note and the Security Documents are collectively
referred to as the "Loan Documents." Capitalized terms not defined herein shall
have the meanings ascribed to them in the Loan Documents.



                                       -2-

<PAGE>



         3. Representations and Warranties. Borrower hereby makes the following
representations and warranties, which shall be continuing in nature and remain
in full force and effect until the Obligations are paid in full, and which shall
be true and correct except as otherwise set forth on the Addendum attached
hereto and incorporated herein by reference (the "Addendum"):

                  3.1. Existence, Power and Authority. Borrower is duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has the power and authority to own and operate its assets and to
conduct its business as now or proposed to be carried on, and is duly qualified,
licensed and in good standing to do business in all jurisdictions where its
ownership of property or the nature of its business requires such qualification
or licensing, except as disclosed on Schedule 3.1 hereto. Borrower is duly
authorized to execute and deliver the Loan Documents to which it is a party, all
necessary action to authorize the execution and delivery of the Loan Documents
to which it is a party has been properly taken, and Borrower is and will
continue to be duly authorized to borrow under this Agreement and to perform all
of the other terms and provisions of the Loan Documents to which it is a party.

                  3.2. Financial Statements. Borrower has delivered or caused to
be delivered its most recent balance sheet, income statement and statement of
cash flows (the "Historical Financial Statements"). The Historical Financial
Statements fairly present in all material respects the financial condition,
assets and liabilities, whether accrued, absolute, contingent or otherwise and
the results of Borrower's operations for the period specified therein. The
Historical Financial Statements have been prepared in accordance with generally
accepted accounting principles ("GAAP") consistently applied from period to
period subject in the case of interim statements to normal year end adjustments
and to any comments and notes reasonably acceptable to Bank.

                  3.3. No Material Adverse Change. Since the date of the most
recent Historical Financial Statements, Borrower has not suffered any damage,
destruction or loss, and no event or condition has occurred or exists, which has
resulted or could reasonably be expected to result in a material adverse change
in its business, assets, operations, financial condition or results of
operation.

                  3.4. Binding Obligations. Borrower has full power and
authority to enter into the transactions provided for in this Agreement and has
been duly authorized to do so by appropriate action of its Board of Directors;
and the Loan Documents to which Borrower is a party, when executed and delivered
by Borrower, will constitute the legal, valid and binding obligations of
Borrower enforceable in accordance with their terms.

                  3.5. No Defaults or Violations. There does not exist any Event
of Default under this Agreement or any default or violation by Borrower of or
under any of the terms, conditions or obligations of: (i) its articles or
certificate of incorporation and regulations or bylaws; (ii) any indenture,
mortgage, deed of trust, franchise, permit, contract, agreement, or other
instrument to which it is a party or by which it is bound; or (iii) any law,
regulation, ruling, order, injunction, decree, condition or other requirement
applicable to or imposed upon it by any law, the action by any court or any
governmental authority or agency; and the consummation of this Agreement and the
transactions set forth herein will not result in any such default or violation.



                                       -3-

<PAGE>



                  3.6. Title to Assets. Borrower has good and marketable title
to the assets reflected on the most recent Financial Statements, free and clear
of all liens and encumbrances, except for (i) current taxes and assessments not
yet due and payable, (ii) assets disposed of by Borrower in the ordinary course
of business since the date of the most recent Financial Statements, and (iii)
those liens or encumbrances, if any, specified on the Addendum.

                  3.7. Litigation. There are no actions, suits, proceedings or
governmental investigations pending or, to the knowledge of Borrower, overtly
threatened against Borrower, which could result in a material adverse change in
its business, assets, operations, financial condition or results of operations
and there is no reasonable basis known to Borrower for any action, suit,
proceeding or investigation which could result in such a material adverse
change. All pending or threatened litigation against Borrower is listed on the
Addendum.

                  3.8. Tax Returns. Borrower has filed all returns and reports
that are required to be filed by it in connection with any federal, state or
local tax, duty or charge levied, assessed or imposed upon it or its property or
withheld by it, including unemployment, social security and similar taxes, and
all of such taxes have been either paid or adequate reserve or other provision
has been made therefor.

                  3.9. Employee Benefit Plans. Each employee benefit plan as to
which Borrower may have any liability complies in all material respects with all
applicable provisions of the Employee Retirement Income Security Act of 1974
("ERISA"), including minimum funding requirements, and (i) no Prohibited
Transaction (as defined under ERISA) has occurred with respect to any such plan,
(ii) no Reportable Event (as defined under Section 4043 of ERISA) has occurred
with respect to any such plan which would cause the Pension Benefit Guaranty
Corporation to institute proceedings under Section 4042 of ERISA, (iii) Borrower
has not withdrawn from any such plan or initiated steps to do so, and (iv) no
steps have been taken to terminate any such plan.

                  3.10. Environmental Matters. Borrower is in compliance, in all
material respects, with all Environmental Laws, including, without limitation,
all Environmental Laws in jurisdictions in which Borrower owns or operates, or
has owned or operated, a facility or site, stores Collateral, arranges or has
arranged for disposal or treatment of hazardous substances, solid waste or other
waste, accepts or has accepted for transport any hazardous substances, solid
waste or other wastes or holds or has held any interest in real property or
otherwise. Except as otherwise disclosed on the Addendum, no litigation or
proceeding arising under, relating to or in connection with any Environmental
Law is pending or, to the best of Borrower's knowledge, threatened against
Borrower, any real property which Borrower holds or has held an interest or any
past or present operation of Borrower. No release, threatened release or
disposal of hazardous waste, solid waste or other wastes is occurring, or to the
best of Borrower's knowledge has occurred, on, under or to any real property in
which Borrower holds any interest or performs any of its operations, in
violation of any Environmental Law. As used in this Section, "litigation or
proceeding" means any demand, claim notice, suit, suit in equity, action,
administrative action, investigation or inquiry whether brought by a
governmental authority or other person, and "Environmental Laws" means all
provisions of laws, statutes, ordinances, rules, regulations, permits, licenses,
judgments, writs, injunctions, decrees, orders, awards and standards promulgated
by any governmental authority concerning health, safety and protection of, or
regulation of the discharge of substances into, the environment.



                                       -4-

<PAGE>



                  3.11. Intellectual Property. Borrower owns or is licensed to
use all patents, patent rights, trademarks, trade names, service marks,
copyrights, intellectual property, technology, knowhow and processes necessary
for the conduct of its business as currently conducted that are material to the
condition (financial or otherwise), business or operations of Borrower.

                  3.12. Regulatory Matters. No part of the proceeds of the Loan
will be used for "purchasing" or "carrying" any "margin stock" within the
respective meanings of each of the quoted terms under Regulation U of the Board
of Governors of the Federal Reserve System as now and from time to time in
effect or for any purpose which violates the provisions of the Regulations of
such Board of Governors.

                  3.13. Solvency. As of the date hereof and after giving effect
to the transactions contemplated by the Loan Documents, (i) the aggregate value
of Borrower's assets will exceed its liabilities (including contingent,
subordinated, unmatured and unliquidated liabilities), (ii) Borrower will have
sufficient cash flow to enable it to pay its debts as they mature, and (iii)
Borrower will not have unreasonably small capital for the business in which it
is engaged.

                  3.14. Year 2000. Borrower has reviewed the areas within its
business and operations which could be adversely affected by, and has developed
a program to address on a timely basis the risk that certain computer
applications used by Borrower may be unable to recognize and perform properly
date sensitive functions involving dates prior to and after December 31, 1999
(the "Year 2000 Problem"). The Year 2000 Problem will not result, and is not
reasonably expected to result, in any material adverse effect on the business,
properties, assets, financial condition, results of operations or prospects of
Borrower, or the ability of Borrower to duly and punctually pay or perform its
obligations hereunder and under the other Loan Documents.

                  3.15. Disclosure. None of the Loan Documents contains or will
contain any untrue statement of material fact or omits or will omit to state a
material fact necessary in order to make the statements contained in this
Agreement or the Loan Documents not misleading. There is no fact known to
Borrower which materially adversely affects or, so far as Borrower can now
foresee, might materially adversely affect the business, assets, operations,
financial condition or results of operation of Borrower and which has not
otherwise been fully set forth in this Agreement or in the Loan Documents.

         4. Affirmative Covenants. Borrower agrees that from the date of
execution of this Agreement until all Obligations have been fully paid and any
commitments of Bank to Borrower have been terminated, Borrower will:

                  4.1. Books and Records. Maintain books and records in
accordance with GAAP and give representatives of Bank access thereto at all
reasonable times, including permission to examine, copy and make abstracts from
any of such books and records and such other information as Bank may from time
to time reasonably request, and Borrower will make available to Bank for
examination copies of any reports, statements or returns which Borrower may make
to or file with any governmental department, bureau or agency, federal or state.
Notwithstanding the foregoing, provided no Event of Default has occurred, Bank
shall give Borrower one (1) day prior notice of any examination of the books and
records.


                                       -5-

<PAGE>




                  4.2.  Financial Reporting.

                           (i) Furnish Borrower's consolidated and consolidating
Financial Statements (10K) to Bank within 90 days after the end of each fiscal
year. Those Financial Statements will be prepared on an audited basis in
accordance with GAAP by an independent certified public accountant selected by
Borrower and satisfactory to Bank. "Financial Statements" means Borrower's
consolidated and consolidating balance sheets, income statements and statements
of cash flows for the year, month or quarter together with year-to-date figures
and comparative figures for the corresponding periods of the prior year. Audited
Financial Statements shall contain the unqualified opinion of an independent
certified public accountant and its examination shall have been made in
accordance with GAAP consistently applied from period to period.

                           (ii) Furnish Borrower's quarterly unaudited
consolidated and consolidating Financial Statements (10Q) within 45 days of
quarter end, in reasonable detail, certified by an authorized officer of
Borrower and prepared in accordance with GAAP applied from period to period.

                           (iii) Furnish Borrower's monthly accounts receivable
and accounts payable aging reports for Borrower, due 15 days after each calendar
month end.

                  4.3. Certificate of No Default. On a quarterly basis, within
forty five (45) days of quarter end Borrower shall also deliver a certificate as
to its compliance with applicable financial covenants (containing detailed
calculations of all financial covenants) for the period then ended and whether
any Event of Default exists, and, if so, the nature thereof and the corrective
measures Borrower proposes to take.

                  4.4. Payment of Taxes and Other Charges. Pay and discharge
when due all indebtedness and all taxes, assessments, charges, levies and other
liabilities imposed upon Borrower, its income, profits, property or business,
except those which currently are being contested in good faith by appropriate
proceedings and for which Borrower shall have set aside adequate reserves or
made other adequate provision with respect thereto acceptable to Bank in its
reasonable discretion.

                  4.5. Maintenance of Existence, Operation and Assets. Do all
things necessary to maintain, renew and keep in full force and effect its
organizational existence and all rights, permits and franchises necessary to
enable it to continue its business; continue in operation in substantially the
same manner as at present; keep its properties in good operating condition and
repair, normal wear and tear excepted; and make all necessary and proper
repairs, renewals, replacements, additions and improvements thereto.

                  4.6. Insurance. Maintain with financially sound and reputable
insurers, insurance with respect to its property and business against such
casualties and contingencies, of such types and in such amounts as is customary
for established companies engaged in the same or similar business and similarly
situated. In the event of a conflict between the provisions of this Section and
the terms of any Security Documents relating to insurance, the provisions in the
Security Documents will control.



                                       -6-

<PAGE>



                  4.7. Compliance with Laws. Comply in all material respects
with laws applicable to Borrower and to the operation of its business (including
any statute, rule or regulation relating to employment practices and pension
benefits or to environmental, occupational and health standards and controls).

                  4.8. Bank Accounts. Establish and maintain at Bank Borrower's
primary depository accounts.

                  4.9. Financial Covenants. Comply with all of the financial and
other covenants set forth on the Addendum.

                  4.10. Additional Reports. Provide prompt written notice to
Bank of the occurrence of any of the following (together with a description of
the action which Borrower proposes to take with respect thereto): (i) any Event
of Default or potential Event of Default, (ii) any litigation filed by or
against Borrower, (iii) any Reportable Event or Prohibited Transaction with
respect to any Employee Benefit Plan(s) (as defined in ERISA) or (iv) any event
which might reasonably result in a material adverse change in the business,
assets, operations, financial condition or results of operation of Borrower.

         5. Negative Covenants. Borrower covenants and agrees that from the date
of execution of this Agreement until all Obligations have been fully paid and
any commitments of Bank to Borrower have been terminated, Borrower will not,
except as set forth in the Addendum, without Bank's prior written consent:

                  5.1. Indebtedness. Incur any secured indebtedness for borrowed
money other than: (i) the Loan and any subsequent indebtedness to Bank; and (ii)
open account trade debt incurred in the ordinary course of business and not past
due.

                  5.2. Liens and Encumbrances. Except as provided in Section
3.6, create, assume or permit to exist any mortgage, pledge, encumbrance or
other security interest or lien upon any assets now owned or hereafter acquired
or enter into any arrangement for the acquisition of property subject to any
conditional sales agreement.

                  5.3. Guarantees. Guarantee, endorse or become contingently
liable for the obligations of any person, firm or corporation, except in
connection with the endorsement and deposit of checks in the ordinary course of
business for collection.

                  5.4. Loans or Advances. Purchase or hold beneficially any
stock, other securities or evidences of indebtedness of, or make or have
outstanding, any loans or advances to, or make any investment or acquire any
interest whatsoever in, any other person, firm or corporation, except
investments disclosed on Borrower's Historical Financial Statements or
acceptable to Bank in its sole discretion.

                  5.5. Merger or Transfer of Assets. Merge or consolidate with
or into any person, firm or corporation or lease, sell, transfer or otherwise
dispose of all, or substantially all, of its property, assets and business
whether now owned or hereafter acquired; except that Borrower may acquire


                                       -7-

<PAGE>



("Permitted Acquistion"), whether by purchase or merger, all or part of the
ownership interests or assets of another person ("Person") provided that each of
the following requirements is met:

                           (i) if Borrower is acquiring the ownership interests
in such Person and such Person becomes a subsidiary of Borrower, such Person
shall become subject to the Loan Documents as a guarantor and shall execute an
irrevocable and unconditional guaranty and suretyship agreement for payment and
performance of the Loan;

                           (ii) the board of directors or other equivalent
governing body of such Person shall have approved such Permitted Acquisition and
Borrower shall have provided Bank with written evidence of such approval;

                           (iii) the business acquired, or the business
conducted by the Person whose ownership interests are being acquired, as
applicable, shall be substantially the same as the business conducted by
Borrower or another activity reasonably incidental thereto;

                           (iv) in the event of a merger with a non-domestic
Person, Borrower shall be the surviving entity;

                           (v) no change of control shall occur with respect to
Borrower and if Borrower is not the surviving entity, the surviving Person shall
assume in writing all of the obligations and liabilities owing under the Loan;

                           (vi) no Event of Default or event, but for the
passage of time, the giving of notice or both would constitute an Event of
Default, shall exist immediately prior to and after giving effect to such
Permitted Acquisition; and

                           (vii) Borrower shall demonstrate that it shall be in
compliance with the financial covenants set forth in this Agreement and the
other Loan Documents after giving effect to such Permitted Acquisition
(including in such computation indebtedness or other liabilities assumed or
incurred in connection with such Permitted Acquisition but excluding income
earned or expenses incurred by the Person to be acquired prior to the date of
such Permitted Acquisition) for the four fiscal quarters immediately following
such Permitted Acquisition, by delivering at least five (5) business days prior
to such Permitted Acquisition a compliance certificate reasonably acceptable to
Bank and Borrower.

                  5.6. Change in Business, Management or Ownership. Make or
permit any material change in the nature of its business as carried on as of the
date hereof, in the composition of its current executive management, or in its
equity ownership.

         6. Events of Default. The occurrence of any of the following will be
deemed to be an Event of Default:

                  6.1. Covenant Default. Borrower shall default in the
performance of any of the covenants or agreements contained in this Agreement;
provided, however, that Borrower shall have fifteen (15) days to cure such
default (to Lender's satisfaction) described in Sections 4.1, 4.4, 4.5, 4.6, and
4.7 from the date of the occurrence of such default.


                                       -8-

<PAGE>



                  6.2. Breach of Warranty. Any Financial Statement,
representation, warranty or certificate made or furnished by Borrower to Bank in
connection with this Agreement shall be false, incorrect or incomplete in any
material respect when made.

                  6.3.  Other Default.  The occurrence of an Event of Default
as defined in the Note or any of the Loan Documents.

Upon the occurrence of an Event of Default, Bank will have all rights and
remedies specified in the Note and the Security Documents and all rights and
remedies (which are cumulative and not exclusive) available under applicable law
or in equity.

         7. Conditions. Bank's obligation to make any advance under the Loan is
subject to the conditions that as of the date of the advance:

                  7.1. No Event of Default. No Event of Default or event which
with the passage of time, provision of notice or both would constitute an Event
of Default shall have occurred and be continuing;

                  7.2. Authorization Documents. Bank shall have been furnished
certified copies of resolutions of the board of directors, the general partners
or the members or managers of any partnership, corporation or limited liability
company that executes this Agreement, the Note or any of the Security Documents
or the other Loan Documents; or other proof of authorization reasonably
satisfactory to Bank;

                  7.3. Receipt of Loan Documents. Bank shall have received the
Loan Documents and such other instruments and documents which Bank may
reasonably request in connection with the transactions provided for in this
Agreement, which may include an opinion of counsel for any party executing any
of the Loan Documents in form and substance satisfactory to Bank.

                  7.4. Payoff Letter and Lien Termination. Bank shall have
received payoff letters (in form and substance reasonably satisfactory to Bank)
and lien termination (including UCC-3 termination statements, mortgages
releases, trademark releases and patent releases) from any other existing lender
or holder of a lien or encumbrance in and to the Collateral.

                  7.5. Landlord and Warehouse Waivers. Bank shall have received,
or waived receipt of landlord, warehouse and mortgage waivers for each location
of Borrower or where any of the Collateral is located.

         8. Expenses. Borrower agrees to pay Bank, upon the closing of this
Agreement, and otherwise promptly after demand, all costs and expenses incurred
by Bank in connection with the preparation, negotiation and delivery of this
Agreement and the other Loan Documents, and any modifications thereto, and the
collection of all of Borrower's Obligations to Bank, including but not limited
to enforcement actions, relating to the Loan, whether through judicial


                                       -9-

<PAGE>



proceedings or otherwise, or in defending or prosecuting any actions or
proceedings arising out of or relating to this Agreement, including reasonable
fees and expenses of counsel (which may include costs of in-house counsel),
expenses for auditors, appraisers and environmental consultants, lien searches,
recording and filing fees and taxes.

         9. Increased Costs. On written demand, together with the written
evidence of the justification therefor, Borrower agrees to pay Bank, all direct
costs incurred and any losses suffered or payments made by Bank as a consequence
of making the Loan by reason of any change in law or regulation or its
interpretation imposing any reserve, deposit, allocation of capital or similar
requirement (including without limitation, Regulation D of the Board of
Governors of the Federal Reserve System) on Bank, its holding company or any of
their respective assets.

         10.  Miscellaneous.

                  10.1. Notices. All notices, demands, requests, consents,
approvals and other communications required or permitted hereunder must be in
writing and will be effective upon receipt. Such notices and other
communications may be hand delivered, sent by facsimile transmission with
confirmation of delivery and a copy sent by first-class mail, or sent by
nationally recognized overnight courier service, to a party's address set forth
below or to such other address as any party may give to the other in writing for
such purpose:

         To Bank:             PNC Bank, Delaware
                              222 Delaware Avenue, 18th Floor
                              Wilmington, Delaware 19801
                              Attention: Theodore J. Prushinski
                              Facsimile No.: (302) 429-2657
                              Telephone No.: (302) 429-1482

         To Borrower:         Strategic Diagnostics Inc.
                              111 Pencader Drive
                              Newark, Delaware 19702
                              Attention: Arthur A. Koch, Jr.
                              Facsimile No.: (302) 456-6798
                              Telephone No.: (302-456-6789

                  10.2. Preservation of Rights. No delay or omission on Bank s
part to exercise any right or power arising hereunder will impair any such right
or power or be considered a waiver of any such right or power, nor will Bank s
action or inaction impair any such right or power. Bank's rights and remedies
hereunder are cumulative and not exclusive of any other rights or remedies which
Bank may have under other agreements, at law or in equity.

                  10.3. Illegality. In case any one or more of the provisions
contained in this Agreement should be invalid, illegal or unenforceable in any
respect, the validity, legality and enforceability of the remaining provisions
contained herein shall not in any way be affected or impaired thereby.



                                      -10-

<PAGE>



                  10.4. Changes in Writing. No modification, amendment or waiver
of any provision of this Agreement nor consent to any departure by Borrower
therefrom will be effective unless made in a writing signed by the party to be
charged, and then such waiver or consent shall be effective only in the specific
instance and for the purpose for which given. No notice to or demand on Borrower
in any case will entitle Borrower to any other or further notice or demand in
the same, similar or other circumstance.

                  10.5. Entire Agreement. This Agreement (including the
documents and instruments referred to herein) constitutes the entire agreement
and supersedes all other prior agreements and understandings, both written and
oral, between the parties with respect to the subject matter hereof.

                  10.6. Counterparts. This Agreement may be signed in any number
of counterpart copies and by the parties hereto on separate counterparts, but
all such copies shall constitute one and the same instrument. Delivery of an
executed counterpart of a signature page to this Agreement by facsimile
transmission shall be effective as delivery of a manually executed counterpart.
Any party so executing this Agreement by facsimile transmission shall promptly
deliver a manually executed counterpart, provided that any failure to do so
shall not affect the validity of the counterpart executed by facsimile
transmission.

                  10.7. Successors and Assigns. This Agreement will be binding
upon and inure to the benefit of Borrower and Bank and their respective
successors and assigns; provided, however, that Borrower may not assign this
Agreement in whole or in part without Bank's prior written consent and Bank at
any time may assign this Agreement in whole or in part.

                  10.8. Interpretation. In this Agreement, unless Bank and
Borrower otherwise agree in writing, the singular includes the plural and the
plural the singular; words importing any gender include the other genders;
references to statutes are to be construed as including all statutory provisions
consolidating, amending or replacing the statute referred to; the word "or"
shall be deemed to include "and/or", the words "including", "includes" and
"include" shall be deemed to be followed by the words "without limitation";
references to articles, sections (or subdivisions of sections) or exhibits are
to those of this Agreement unless otherwise indicated; and references to
agreements and other contractual instruments shall be deemed to include all
subsequent amendments and other modifications to such instruments, but only to
the extent such amendments and other modifications are not prohibited by the
terms of this Agreement. Section headings in this Agreement are included for
convenience of reference only and shall not constitute a part of this Agreement
for any other purpose. Unless otherwise specified in this Agreement, all
accounting terms shall be interpreted and all accounting determinations shall be
made in accordance with GAAP. If this Agreement is executed by more than one
party as Borrower, the obligations of such persons or entities will be joint and
several.

                  10.9. Indemnity. Borrower agrees to indemnify each of Bank,
its directors, officers and employees and each legal entity, if any, who
controls Bank (the Indemnified Parties) and to hold each Indemnified Party
harmless from and against any and all claims, damages, losses, liabilities and
expenses (including, without limitation, all reasonable fees and charges of
internal or external counsel with whom any Indemnified Party may consult and all
expenses of litigation or preparation therefor) which any Indemnified Party may
incur or which may be asserted against any Indemnified Party in connection with
or arising out of the matters referred to in this Agreement or in the other Loan


                                      -11-

<PAGE>



Documents by any person, entity or governmental authority (including any person
or entity claiming derivatively on behalf of Borrower), whether (a) arising from
or incurred in connection with any breach of a representation, warranty or
covenant by Borrower, or (b) arising out of or resulting from any suit, action,
claim, proceeding or governmental investigation, pending or threatened, whether
based on statute, regulation or order, or tort, or contract or otherwise, before
any court or governmental authority, which arises out of or relates to this
Agreement, any other Loan Document, or the use of the proceeds of the Loan;
provided, however, that the foregoing indemnity agreement shall not apply to
claims, damages, losses, liabilities and expenses to the extent attributable to
an Indemnified Party's gross negligence or willful misconduct. The indemnity
agreement contained in this Section shall survive the termination of this
Agreement, payment of any Loan and assignment of any rights hereunder. Borrower
may participate at its expense in the defense of any such action or claim.

                  10.10. Assignments and Participations. At any time, without
any notice to Borrower, Bank may sell, assign, transfer, negotiate, grant
participations in, or otherwise dispose of all or any part of Bank's interest in
the Loan. Borrower hereby authorizes Bank to provide, without any notice to
Borrower, any information concerning Borrower, including information pertaining
to Borrower's financial condition, business operations or general
creditworthiness, to any person or entity which may succeed to or participate in
all or any part of Bank's interest in the Loan.

                  10.11. Governing Law and Jurisdiction. This Agreement has been
delivered to and accepted by Bank and will be deemed to be made in the State
where Bank's office indicated above is located. THIS AGREEMENT WILL BE
INTERPRETED AND THE RIGHTS AND LIABILITIES OF THE PARTIES HERETO DETERMINED IN
ACCORDANCE WITH THE LAWS OF THE STATE WHERE BANK's OFFICE INDICATED ABOVE IS
LOCATED, EXCLUDING ITS CONFLICT OF LAWS RULES. Borrower hereby irrevocably
consents to the exclusive jurisdiction of any state or federal court in the
county or judicial district where Bank's office indicated above is located;
provided that nothing contained in this Agreement will prevent Bank from
bringing any action, enforcing any award or judgment or exercising any rights
against Borrower individually, against any security or against any property of
Borrower within any other county, state or other foreign or domestic
jurisdiction. Bank and Borrower agree that the venue provided above is the most
convenient forum for both Bank and Borrower. Borrower waives any objection to
venue and any objection based on a more convenient forum in any action
instituted under this Agreement.

                  10.12. WAIVER OF JURY TRIAL. EACH OF BORROWER AND BANK
IRREVOCABLY WAIVES ANY AND ALL RIGHT IT MAY HAVE TO A TRIAL BY JURY IN ANY
ACTION, PROCEEDING OR CLAIM OF ANY NATURE RELATING TO THIS AGREEMENT, ANY
DOCUMENTS EXECUTED IN CONNECTION WITH THIS AGREEMENT OR ANY TRANSACTION
CONTEMPLATED IN ANY OF SUCH DOCUMENTS. BORROWER AND BANK ACKNOWLEDGE THAT THE
FOREGOING WAIVER IS KNOWING AND VOLUNTARY.

Borrower acknowledges that it has read and understood all the provisions of this
Agreement, including the waiver of jury trial, and has been advised by counsel
as necessary or appropriate.

                          SIGNATURES ON FOLLOWING PAGE




                                      -12-

<PAGE>



         WITNESS the due execution hereof as a document under seal, as of the
date first written above.

ATTEST:                             STRATEGIC DIAGNOSTICS INC.


By: /s/ Martha C. Ryder             By: /s/ Arthur A. Koch
    ----------------------------        ------------------------------
Print Name: Martha C. Ryder         Print Name: Arthur A. Koch
Title:                              Title: COO


   [Corporate Seal]                 PNC BANK, DELAWARE


                                    By: /s/ Theodore J. Prushinski
                                        ---------------------------------------
                                         Theodore J. Prushinski, Vice President




                                      -13-

<PAGE>


                                    ADDENDUM
                                    --------

         THIS ADDENDUM is to that certain Loan Agreement dated __________ ____,
2000 between Strategic Diagnostics Inc., as Borrower, and PNC Bank, Delaware, as
Bank. Capitalized terms used in this Addendum and not otherwise defined shall
have the meanings given them in the Agreement. Section numbers below refer to
the sections of the Agreement.

3.6  Title to Assets. Describe additional liens and encumbrances below:



3.7 Litigation. Describe pending or threatened litigation, proceedings, etc.
below:

                                    - None -

3.10 Environmental Matters. Describe pending or threatened environmental matters
below:

                                    - None -

4.9.  Financial Covenants.

         a. Borrower shall maintain, on a consolidated basis, a ratio of Funded
Debt to EBITDA of not more than 3.25 to 1, and such ratio will be tested
quarterly on a rolling four quarter basis.

         b. Borrower shall maintain, on a consolidated basis, a ratio of EBITDA
to the sum of Current Maturities plus interest plus taxes of not less than 1.50
to 1, and such ratio will be tested quarterly on a rolling four quarter basis.

            As used herein:

         "Current Maturities" means Borrower's current principal maturities of
all indebtedness for borrowed money (including but not limited to amortization
of capitalized lease obligations) having an original term of one year or more,
as shown on Borrower's consolidated balance sheet as of the end of the prior
fiscal year, together with any prepayments of such indebtedness made during the
prior fiscal year.

         "EBITDA" means Borrower's earnings before interest, taxes, depreciation
and amortization, but shall exclude "Acquired Research and Development" charges
(as carried on Borrower's books).

         "Funded Debt" means all borrowed monies of Borrower, including the
Loan.

5.  Negative Covenants.

                                    - None -

                                      -14-