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                                    TERM NOTE
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$4,000,000                                                           May 5, 2000

         FOR VALUE RECEIVED, STRATEGIC DIAGNOSTICS INC., a Delaware corporation
(the "Borrower"), with an address at 111 Pencader Drive, Newark, Delaware 19702,
promises to pay to the order of PNC BANK, DELAWARE (the "Bank"), in lawful money
of the United States of America in immediately available funds at its offices
located at 222 Delaware Avenue, Wilmington, Delaware 19801, or at such other
location as the Bank may designate from time to time, the principal sum of FOUR
MILLION and 00/100 DOLLARS ($4,000,000), together with interest accruing on the
outstanding principal balance from the date hereof, all as provided below:

         1. Rate of Interest. Amounts outstanding under this Note will bear
interest at a rate per annum equal to the sum of (A) the Euro-Rate plus (B) the
Applicable Margin for the Term Loan (as defined in the Loan Agreement (defined
below)), for the applicable Euro-Rate Interest Period.

For purposes hereof, the following terms shall have the following meanings:

         "Business Day" shall mean any day other than a Saturday or Sunday or a
         legal holiday on which commercial banks are authorized or required to
         be closed for business in Wilmington, Delaware.

         "Euro-Rate" shall mean, with respect to any amounts to which the
         Euro-Rate applies for the applicable Euro-Rate Interest Period, the
         interest rate per annum determined by the Bank by dividing (the
         resulting quotient rounded upwards, if necessary, to the nearest
         1/100th of 1%) (i) the rate of interest determined by the Bank in
         accordance with its usual procedures (which determination shall be
         conclusive absent manifest error) to be the eurodollar rate two (2)
         Business Days prior to the first day of such Euro-Rate Interest Period
         for such amounts and having a borrowing date and a maturity comparable
         to such Euro-Rate Interest Period by (ii) a number equal to 1.00 minus
         the Euro-Rate Reserve Percentage.

         "Euro-Rate Interest Period" shall mean the period of one (1) month
         commencing on the date of disbursement of an advance (or the date of
         conversion of an advance to the Euro-Rate, as the case may be) and
         each successive period selected by the Borrower thereafter; provided,
         that if a Euro-Rate Interest Period would end on a day which is not a
         Business Day, it shall end on the next succeeding Business Day, unless
         such day falls in the succeeding calendar month in which case the
         Euro-Rate Interest Period shall end on the next preceding Business Day.
         In no event shall any Euro-Rate Interest Period end on a day after the
         Expiration Date.

         "Euro-Rate Reserve Percentage" shall mean the maximum effective
         percentage in effect on such day as prescribed by the Board of
         Governors of the Federal Reserve System (or any successor) for
         determining the reserve requirements (including, without limitation,
         supplemental, marginal and emergency reserve requirements) with respect
         to eurocurrency funding (currently referred to as "Eurocurrency
         liabilities").



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         The Euro-Rate shall be adjusted with respect to any amounts to which
the Euro-Rate applies on and as of the effective date of any change in the
Euro-Rate Reserve Percentage. The Bank shall give prompt notice to the Borrower
of the Euro-Rate as determined or adjusted in accordance herewith, which
determination shall be conclusive absent manifest error.

         If the Bank determines (which determination shall be final and
conclusive) that, by reason of circumstances affecting the eurodollar market
generally, deposits in dollars (in the applicable amounts) are not being offered
to banks in the eurodollar market for the selected term, or adequate means do
not exist for ascertaining the Euro-Rate, then the Bank shall give notice
thereof to the Borrower. Thereafter, until the Bank notifies the Borrower that
the circumstances giving rise to such suspension no longer exist, (a) the
availability of the Euro-Rate shall be suspended, and (b) the interest rate for
all amounts then bearing interest under the Euro-Rate shall be converted at the
expiration of the then current Euro-Rate Interest Period(s) to the Base Rate (as
defined below).

          "Base Rate" means a rate of interest per annum which is at all times
         equal to the sum of (A) the Prime Rate plus (B) the otherwise
         Applicable Margin less (C) an amount equal to the Prime Rate minus the
         Euro-Rate on the last day of its availability. For purposes hereof, the
         term "Prime Rate" shall mean the rate publicly announced by the Bank
         from time to time as its prime rate. The Prime Rate is determined from
         time to time by the Bank as a means of pricing some loans to its
         borrowers. The Prime Rate is not tied to any external rate of interest
         or index, and does not necessarily reflect the lowest rate of interest
         actually charged by the Bank to any particular class or category of
         customers. If and when the Prime Rate changes, the rate of interest
         with respect to any amounts to which the Base Rate applies will change
         automatically without notice to the Borrower, effective on the date of
         any such change. There are no required minimum interest periods for
         amounts bearing interest under the Base Rate.

         In addition, if, after the date of this Note, the Bank shall determine
(which determination shall be final and conclusive) that any enactment,
promulgation or adoption of or any change in any applicable law, rule or
regulation, or any change in the interpretation or administration thereof by a
governmental authority, central bank or comparable agency charged with the
interpretation or administration thereof, or compliance by the Bank with any
guideline, request or directive (whether or not having the force of law) of any
such authority, central bank or comparable agency shall make it unlawful or
impossible for the Bank to make or maintain or fund loans under the Euro-Rate,
the Bank shall notify the Borrower. Upon receipt of such notice, until the Bank
notifies the Borrower that the circumstances giving rise to such determination
no longer apply, (a) the availability of the Euro-Rate shall be suspended, and
(b) the interest rate on all amounts then bearing interest under the Euro-Rate
shall be converted to the Base Rate either (i) on the last day of the then
current Euro-Rate Interest Period(s) if the Bank may lawfully continue to
maintain any indebtedness under the Euro-Rate to such day, or (ii) immediately
if the Bank may not lawfully continue to maintain any indebtedness under the
Euro-Rate.

Interest hereunder will be calculated on the basis of a year of 360 days for the
actual number of days elapsed. In no event will the rate of interest hereunder
exceed the maximum rate allowed by law.

         2. Payment of Interest. The Borrower shall pay accrued interest on the
unpaid principal balance of this Note in arrears: (a) for the portions hereunder
bearing interest under the Base Rate, on the first day of each month during the


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term hereof, (b) for the portions hereunder bearing interest under the
Euro-Rate, on the last day of the respective Euro-Rate Interest Period for such
portion, and (c) for all outstanding amounts, at maturity, whether by
acceleration of this Note or otherwise, and after maturity, on demand until paid
in full.

         3. Payment of Principal. Principal shall be due and payable in
thirty-six (36) equal consecutive monthly installments in the amount of
$111,111.11 each, commencing on June 5, 2000 and continuing on the fifth day of
each month thereafter to and including May 5, 2003. Any outstanding principal
and accrued interest shall be due and payable in full on May 5, 2003.

         If any payment under this Note shall become due on a Saturday, Sunday
or public holiday under the laws of the State where the Bank's office indicated
above is located, such payment shall be made on the next succeeding business day
and such extension of time shall be included in computing interest in connection
with such payment. The Borrower hereby authorizes the Bank to charge the
Borrower's deposit account at the Bank for any payment when due hereunder.
Payments received will be applied to reasonable charges, fees and expenses
(including reasonable attorneys' fees), accrued interest and principal in any
order the Bank may choose, in its sole discretion.

         4. Late Payments; Default Rate. If the Borrower fails to make any
payment of principal, interest or other amount coming due pursuant to the
provisions of this Note within fifteen (15) calendar days of the date due and
payable, the Borrower also shall pay to the Bank a late charge equal to the
lesser of five percent (5.00%) of the amount of such payment or $100.00 (the
"Late Charge"). Such 15-day period shall not be construed in any way to extend
the due date of any such payment. Upon maturity, whether by acceleration, demand
or otherwise, and at the Bank's option upon the occurrence of any Event of
Default (as hereinafter defined) and during the continuance thereof, this Note
shall bear interest at a rate per annum (based on a year of 360 days and actual
days elapsed) which shall be two percentage points (2.00%) in excess of the
interest rate in effect from time to time under this Note but not more than the
maximum rate allowed by law (the "Default Rate"). The Default Rate shall
continue to apply whether or not judgment shall be entered on this Note. Both
the Late Charge and the Default Rate are imposed as liquidated damages for the
purpose of defraying the Bank's expenses incident to the handling of delinquent
payments, but are in addition to, and not in lieu of, the Bank's exercise of any
rights and remedies hereunder, under the other Loan Documents (as defined below)
or under applicable law, and any fees and expenses of any agents or attorneys
which the Bank may employ. In addition, the Default Rate reflects the increased
credit risk to the Bank of carrying a loan that is in default. The Borrower
agrees that the Late Charge and Default Rate are reasonable forecasts of just
compensation for anticipated and actual harm incurred by the Bank, and that the
actual harm incurred by the Bank cannot be estimated with certainty and without
difficulty.

         5. Prepayment. The Borrower shall have the right to prepay at any time
and from time to time, in whole or in part, without penalty, any amount
hereunder which is accruing interest under the Base Rate. If the Borrower
prepays (whether voluntary, on default or otherwise) all or any part of any
amount which is accruing interest under the Euro-Rate on any day other than the
last day of the applicable Euro-Rate Interest Period, the Borrower shall pay to
the Bank, on demand therefor, all amounts due pursuant to paragraph 6 below.



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         6. Yield Protection. The Borrower shall pay to the Bank, promptly after
demand therefor, together with the written evidence of the justification
therefor, all direct costs incurred, losses suffered or payments made by Bank 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 the Bank, its holding company or any of their respective
assets. In addition, the Borrower agrees to indemnify the Bank against any
liabilities, losses or expenses (including loss of margin, any loss or expense
sustained or incurred in liquidating or employing deposits from third parties,
and any loss or expense incurred in connection with funds acquired to effect,
fund or maintain any of the Borrower's indebtedness (or any part thereof)
bearing interest under the Euro-Rate which the Bank sustains or incurs as a
consequence of either (i) the Borrower's failure to make a payment on the due
date thereof, (ii) the Borrower's revocation (expressly, by later inconsistent
notices or otherwise) in whole or in part of any notice given to Bank to
request, convert, renew or prepay any advance, or (iii) the Borrower's payment,
prepayment or conversion of any advance bearing interest under the Euro-Rate on
a day other than the last day of the applicable Euro-Rate Interest Period. The
Bank's determination of an amount payable under this paragraph shall, in the
absence of manifest error, be conclusive and shall be payable promptly after
demand.

         7. Other Loan Documents. This Note is issued in connection with a loan
agreement between the Borrower and the Bank dated as of the date hereof (as
amended, modified or renewed from time to time, the "Loan Agreement"), and the
other agreements and documents executed in connection therewith or referred to
therein, the terms of which are incorporated herein by reference (as amended,
modified or renewed from time to time, collectively with the Loan Agreement, the
"Loan Documents"), and is secured by the property described in the Loan
Documents and by such other collateral as previously may have been or may in the
future be granted to the Bank to secure this Note.

         8. Events of Default. The occurrence of any of the following events
will be deemed to be an "Event of Default" under this Note: (i) the nonpayment
of any principal, interest or other indebtedness under this Note when due; (ii)
the occurrence of any event of default or default and the lapse of any notice or
cure period under any Loan Document or any other debt, liability or obligation
to the Bank of any Obligor; (iii) the filing by or against any Obligor of any
proceeding in bankruptcy, receivership, insolvency, reorganization, liquidation,
conservatorship or similar proceeding (and, in the case of any such proceeding
instituted against any Obligor, such proceeding is not dismissed or stayed
within 90 days of the commencement thereof, provided that the Bank shall not be
obligated to advance additional funds during such period); (iv) any assignment
by any Obligor for the benefit of creditors, or any levy, garnishment,
attachment or similar proceeding is instituted against any property of any
Obligor held by or deposited with the Bank; (v) a default with respect to any
other indebtedness of any Obligor for borrowed money, if the effect of such
default is to cause or permit the acceleration of such debt and such
acceleration would have a material adverse effect upon Borrower's business,
operations, property (including, the Collateral) or prospects; (vi) the
commencement of any foreclosure or forfeiture proceeding, execution or
attachment against any collateral securing the obligations of any Obligor to the
Bank; (vii) the entry of a final judgment against any Obligor and the failure of
such Obligor to discharge or bond the judgment within thirty (30) days of the
entry thereof; (viii) any material adverse change in any Obligor's business,
assets, operations, financial condition or results of operations; (ix) any
Obligor ceases doing business as a going concern; (x) the revocation or
attempted revocation, in whole or in part, of any guarantee by any Guarantor;
(xi) the death or legal incompetency of any individual Obligor or, if any


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Obligor is a partnership, the death or legal incompetency of any individual
general partner; or (xii) any representation or warranty made by any Obligor to
the Bank in any Loan Document, or any other documents now or in the future
evidencing or securing the obligations of any Obligor to the Bank, is false,
erroneous or misleading in any material respect; or (xiii) any Obligor's failure
to observe or perform any covenant or other agreement with the Bank contained in
any Loan Document or any other documents now or in the future evidencing or
securing the obligations of any Obligor to the Bank. As used herein, the term
"Obligor" means any Borrower and any Guarantor, and the term "Guarantor" means
any guarantor of the Borrower's obligations to the Bank existing on the date of
this Note or arising in the future.

         Upon the occurrence and during the continuance of an Event of Default:
(a) the Bank shall be under no further obligation to make advances hereunder;
(b) if an Event of Default specified in clause (iii) or (iv) above shall occur,
the outstanding principal balance and accrued interest hereunder together with
any additional amounts payable hereunder shall be immediately due and payable
without demand or notice of any kind; (c) if any other Event of Default shall
occur, the outstanding principal balance and accrued interest hereunder together
with any additional amounts payable hereunder, at the Bank's option and without
demand or notice of any kind, may be accelerated and become immediately due and
payable; (d) at the Bank's option, this Note will bear interest at the Default
Rate from the date of the occurrence of the Event of Default; and (e) the Bank
may exercise from time to time any of the rights and remedies available under
the Loan Documents or under applicable law.

         9. Power to Confess Judgment. The Borrower hereby empowers any attorney
of any court of record, during the existence of any Event of Default hereunder,
to appear for the Borrower and, with or without complaint filed, confess
judgment, or a series of judgments, against the Borrower in favor of the Bank or
any holder hereof for the entire principal balance of this Note, all accrued
interest and all other amounts due hereunder, together with costs of suit and an
attorney's commission of the greater of 10% of such principal and interest or
$1,000 added as a reasonable attorney's fee, and for doing so, this Note or a
copy verified by affidavit shall be a sufficient warrant. The Borrower hereby
forever waives and releases all errors in said proceedings and all rights of
appeal and all relief from any and all appraisement, stay or exemption laws of
any state now in force or hereafter enacted. Interest on any such judgment shall
accrue at the Default Rate.

         No single exercise of the foregoing power to confess judgment, or a
series of judgments, shall be deemed to exhaust the power, whether or not any
such exercise shall be held by any court to be invalid, voidable, or void, but
the power shall continue undiminished and it may be exercised from time to time
as often as the Bank shall elect until such time as the Bank shall have received
payment in full of the debt, interest and costs. Notwithstanding the attorney's
commission provided for in the preceding paragraph (which is included in the
warrant for purposes of establishing a sum certain), the amount of attorneys'
fees that the Bank may recover from the Borrower shall not exceed the actual
attorneys' fees incurred by the Bank.

         10. Right of Setoff. In addition to all liens upon and rights of setoff
against the Borrower's money, securities or other property given to the Bank by
law, the Bank shall have, with respect to the Borrower's obligations to the Bank
under this Note and to the extent permitted by law, a contractual possessory
security interest in and a contractual right of setoff against, and the Borrower


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hereby assigns, conveys, delivers, pledges and transfers to the Bank all of the
Borrower's right, title and interest in and to, all of the Borrower's deposits,
moneys, securities and other property now or hereafter in the possession of or
on deposit with, or in transit to, the Bank or any other direct or indirect
subsidiary of PNC Bank Corp., whether held in a general or special account or
deposit, whether held jointly with someone else, or whether held for safekeeping
or otherwise, excluding, however, all IRA, Keogh, and trust accounts. Every such
security interest and right of setoff may be exercised without demand upon or
notice to the Borrower. Every such right of setoff shall be deemed to have been
exercised immediately upon the occurrence of an Event of Default hereunder
without any action of the Bank, although the Bank may enter such setoff on its
books and records at a later time.

         11. Miscellaneous. All notices, demands, requests, consents, approvals
and other communications required or permitted hereunder must be in writing
(except as may be agreed otherwise above with respect to borrowing requests) 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 the addresses for the Bank and the Borrower set forth above
or to such other address as either may give to the other in writing for such
purpose. No delay or omission on the 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 the Bank's action or inaction impair any
such right or power. No modification, amendment or waiver of any provision of
this Note nor consent to any departure by the Borrower therefrom will be
effective unless made in a writing signed by the Bank. The Borrower agrees to
pay promptly after demand, to the extent permitted by law, all costs and
expenses incurred by the Bank in the enforcement of its rights in this Note and
in any security therefor, including without limitation reasonable fees and
expenses of the Bank's counsel. If any provision of this Note is found to be
invalid by a court, all the other provisions of this Note will remain in full
force and effect. The Borrower and all other makers and indorsers of this Note
hereby forever waive presentment, protest, notice of dishonor and notice of
non-payment. The Borrower also waives all defenses based on suretyship or
impairment of collateral. If this Note is executed by more than one Borrower,
the obligations of such persons or entities hereunder will be joint and several.
This Note shall bind the Borrower and its successors and assigns, and the
benefits hereof shall inure to the benefit of the Bank and its successors and
assigns; provided, however, that the Borrower may not assign this Note in whole
or in part without the Bank's written consent and the Bank at any time may
assign this Note in whole or in part.

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


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         12. WAIVER OF JURY TRIAL. THE BORROWER IRREVOCABLY WAIVES ANY AND ALL
RIGHTS THE BORROWER MAY HAVE TO A TRIAL BY JURY IN ANY ACTION, PROCEEDING OR
CLAIM OF ANY NATURE RELATING TO THIS NOTE, ANY DOCUMENTS EXECUTED IN CONNECTION
WITH THIS NOTE OR ANY TRANSACTION CONTEMPLATED IN ANY OF SUCH DOCUMENTS. THE
BORROWER ACKNOWLEDGES THAT THE FOREGOING WAIVER IS KNOWING AND VOLUNTARY.

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

         WITNESS the due execution hereof as a document under seal, as of the
date first written above, with the intent to be legally bound hereby.

ATTEST:                                  STRATEGIC DIAGNOSTICS INC.


By: /s/ Martha C. Ryder                  By: /s/ Arthur Koch              (SEAL)
    -------------------------                ----------------------------
Print Name: Martha C. Ryder              Print Name: Arthur Koch
Title:_____________________________      Title: COO


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