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**Exhibit    31.1**

**Rule    13a-14(a)/15d-14(a) Certification**

| I,            MatthewH. Knight, certify that: |
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| 1.                                            | I            have reviewed this Quarterly Report as of and for the period ended      June 30, 2005 on Form 10-Q/A of Strategic Diagnostics Inc. (the “registrant”); |
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| 2.                                            | Based on my knowledge, this report does not contain any untrue statement            of a material fact or omit to state a material fact necessary to            make the statements made, in light of the circumstances under which            such statements were made, not misleading with respect to the period      covered by this report; |
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| 3.                                            | Based            on my knowledge, the financial statements, and other financial information            included in this report, fairly present in all material            respects the financial condition, results of operations and cash            flows of the registrant as of, and for, the periods presented in      this report; |
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| 4.                                            | The            registrant’s other certifying officer and I are responsible            for establishing and maintaining disclosure controls and procedures            (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the      registrant and have: |
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|                                          | a) | Designed such disclosure controls and procedures, or caused such            disclosure controls and procedures to be designed under our supervision,            to ensure that material information relating to the registrant, including            its consolidated subsidiaries, is made known to us by others within            those entities, particularly during the period in which this report      is being prepared; |
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|                                          | b) | Evaluated the effectiveness of the registrant’s disclosure controls            and procedures and presented in this report our conclusions about            the effectiveness of the disclosure controls and procedures, as of            the end of the period covered by this report based on such evaluation;      and |
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|                                          | c) | Disclosed in this report any change in the registrant’s internal            control over financial reporting that occurred during the registrant's            most recent fiscal quarter (the registrant’s            fourth fiscal quarter in the case of an annual report) that has materially            affected, or            is reasonably likely to materially affect, the registrant's internal      control over financial reporting; and |
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| 5.                                            | The registrant’s other certifying officer and I have disclosed,            based on our most recent evaluation of internal control over financial            reporting, to the registrant’s auditors and the audit committee            of the registrant’s board of directors (or persons performing            the equivalentfunctions): |
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|                                          | a) | All significant deficiencies and material weaknesses in the design            or operation of internal control over financial reporting which are            reasonably likely to adversely affect the registrant’s ability            torecord, process, summarize and report financial information; and |
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|                                          | b) | Any fraud, whether or not material, that involves management or other            employees who have a significant role in the registrant’s internal            control over      financial reporting. |
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| Date:  | March 16, 2006  | /s/    | Matthew H. Knight        |
|-------------|----------------------|--------|-------------------------------|
|             |                      |        |                               |
|        |                 |   | Matthew H. Knight        |
|        |                 |   | Chief Executive Officer  |

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