----

| Sixth Amendment to Loan Documents |  |
|-----------------------------------|--|

----

----

|             |           |                       |        |                     |   |   |   |   |
|------------------|----------------|----------------------------|-------------|--------------------------|--------|--------|--------|--------|
| [CORPORATE SEAL] |           | STRATEGIC DIAGNOSTICS INC. |
|             |           |                       |
| Attest:          | /s/ Ric Rumble |                       | By:         | /s/ Anthony J. Simonetta |
|             |           |                       |
| Print Name:      | Ric Rumble     |                       | Print Name: | Anthony J. Simonetta     |
|             |           |                       |        |                     |
| Title:           | VP             |                       | Title:      | Secretary and CFO        |

|   |   |                           |             |   |   |
|--------|--------|--------------------------------|------------------|--------|--------|
|   |   | PNC BANK, NATIONAL ASSOCIATION |
|   |   |                           |
|   |   | By:                            | /s/ John H. Hall |
|   |   |                           |
|   |   | Print Name:                    | John H. Hall     |
|   |   |                           |             |
|   |   | Title:                         | Vice President   |

----

| A.     | The “Loan Documents” that are the subject of this Amendment include the following (as any of the foregoing have previously been amended, modified or otherwise supplemented): |
|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |                                                                                                                                                                                      |   |
|   | 1.                                                                                                                                                                                        | Loan Agreement dated May 5, 2000, as amended by an Amendment to Loan Documents dated December 13, 2001, a Second Amendment to Loan Documents dated April 25, 2002, a Third Amendment to Loan Documents dated October 24, 2002, a Fourth Amendment to Loan Documents dated February 11, 2003 and a Fifth Amendment to Loan Documents dated February 16, 2004 (the “Loan Agreement”) |
|   |                                                                                                                                                                                      |   |
|   | 2.                                                                                                                                                                                        | $5,000,000 Committed Line of Credit Note dated May 5, 2000 (the “Line of Credit Note”) |
|   |                                                                                                                                                                                      |   |
|   | 3.                                                                                                                                                                                        | Term Note B dated December 13, 2001 in the original principal amount of $1,500,000 (the “Term Note”) |
|   |                                                                                                                                                                                      |   |
|   | 4.                                                                                                                                                                                        | Working Cash®, Line of Credit, Investment Sweep Rider dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 5.                                                                                                                                                                                        | Borrowing Base Rider dated May 5, 2000 (the “Borrowing Base Rider”) |
|   |                                                                                                                                                                                      |   |
|   | 6.                                                                                                                                                                                        | , Mortgage, Assignment of Rents, Security Agreement and Fixture Filing dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 7.                                                                                                                                                                                        | Assignment of Rents and Leases dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 8.                                                                                                                                                                                        | Mortgage, Assignment of Rents, Security Agreement and Fixture Filing dated December 13, 2001 |
|   |                                                                                                                                                                                      |   |
|   | 9.                                                                                                                                                                                        | Security Agreement dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 10.                                                                                                                                                                                       | Patent Security Agreement dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 11.                                                                                                                                                                                       | Trademark Security Agreement dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 12.                                                                                                                                                                                       | Rider to Security Rider- Patents dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 13.                                                                                                                                                                                       | Rider to Security Rider - Trademarks dated May 5, 2000 |
|   |                                                                                                                                                                                      |   |
|   | 14.                                                                                                                                                                                       | All other documents, instruments, agreements, and certificates executed and delivered in connection with the Loan Documents listed in this Section A. |
|   |                                                                                                                                                                                      |   |
| B.     | The Loan Documents are amended as follows:                                                                                                                                                |
|   |                                                                                                                                                                                      |   |
|   | 1.                                                                                                                                                                                        | The Expiration Date, as set forth in the Line of Credit Note, is hereby extended from August 31, 2005 to August 31, 2006, effective September 1, 2005. |
|   |                                                                                                                                                                                      |   |
|   | 2.                                                                                                                                                                                        | The Loan Agreement is hereby amended as follows: |
|   |                                                                                                                                                                                      |   |
|   |                                                                                                                                                                                      | (a) | The last sentence of Section 1.1 of the Loan Agreement is hereby amended and restated to read in its entirety as follows: |
|   |                                                                                                                                                                                      |   |   |   |
|   |                                                                                                                                                                                      |   |   | “Borrower will submit monthly Borrowing Base certificates within fifteen (15) days of each month end when there is an outstanding balance under the Line of Credit, or if there is no outstanding balance under the Line of Credit, at the time of such request for an advance under the Line of Credit, which Borrowing Base certificates shall include a detailed listing of “datings” and a detailed list of all the Accounts of Account Debtors whose aggregate amount of Accounts exceed twenty percent (20% of all of the Borrower’s Accounts.” |

----

|   |   | (b) | The Applicable Margin chart contained in Section 1.2 of the Loan Agreement is hereby amended and restated to read in its entirety as follows: |
|--------|--------|-----|-----------------------------------------------------------------------------------------------------------------------------------------------|

|   | Ratio of FundedDebt to EBITDA |   | Applicable MarginLine of Credit |   | Applicable MarginTerm Loan B |   |
|--------|-------------------------------|--------|---------------------------------|--------|------------------------------|--------|
|   |                          |   |                            |   |                         |   |
|   | > 3.00: 1,00               |   | 250 basis points                |   | 275 basis points             |   |
|   | < 3.00 ≥ 2.75        |   | 225 basis points                |   | 250 basis points             |   |
|   | < 2.75 ≥ 2.50        |   | 200 basis points                |   | 225 basis points             |   |
|   | < 2.50 ≥ 2.25   |   | 175 basis points                |   | 200 basis points             |   |
|   | < 2.25                     |   | 150 basis points                |   | 175 basis points             |   |

|   |                                                                                                                                                                                                                                                                                      | (c)                                                                                                      | Sections 4.2(ii) and (iii) of the Loan Agreement are hereby amended and restated to read in their entirety as follows:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |                                                                                                                                                                                                                                                                                      |                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
|   |                                                                                                                                                                                                                                                                                      |                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | “(ii) Furnish Borrower’s quarterly (except the fourth quarter) unaudited consolidated and consolidating Financial Statements (10Q) within forty-five (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 at the request of the Bank or when there is an outstanding balance under the Line of Credit, within fifteen (15) days after the end of each calendar month.” |
|   |                                                                                                                                                                                                                                                                                      |                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
|   | 3.                                                                                                                                                                                                                                                                                        | Section 2 of the Borrowing Base Rider is hereby amended and restated to read in its entirety as follows: |
|   |                                                                                                                                                                                                                                                                                      |                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
|   |                                                                                                                                                                                                                                                                                      |                                                                                                     | “2. Borrowing Base Certificates. In addition to any and all provisions of the other Loan Documents which establish conditions to the Borrower’s ability to request and obtain any advance under the Facility, the Borrower may not request an advance under the Facility unless a Borrowing Base Certificate (as hereinafter defined) shall have been delivered to the Bank within fifteen (15) days of the end of each month when there is an outstanding balance under the Facility, or if there is no outstanding balance under the Facility, at the tune of such request for an advance under the Facility.” |
|   |                                                                                                                                                                                                                                                                                      |                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
| C.     | Conditions to Effectiveness of Amendment: The Bank’s willingness to agree to the amendments set forth in this Amendment is subject to the execution by all parties and delivery to the Bank of this Amendment, and Resolutions for Extensions of Credit and Incumbency Certificate. |