**Exhibit31.1**

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

I, Matthew H. Knight,certify that:

| 1.     | I have        reviewed this Quarterly Report as of and for the period ended March 31, 2005 on Form 10-Q/A of Strategic Diagnostics    Inc. (the “registrant”);                                                                                                                                                         |
|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |                                                                                                                                                                                                                                                                                                                             |   |
| 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;    |
|   |                                                                                                                                                                                                                                                                                                                             |   |
| 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;                  |
|   |                                                                                                                                                                                                                                                                                                                             |   |
| 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) and15d-15(e)) for the registrant and have:                                                                             |
|   |                                                                                                                                                                                                                                                                                                                             |   |
|   | 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; |
|   |                                                                                                                                                                                                                                                                                                                             |   |
|   | b)                                                                                                                                                                                                                                                                                                                               | Evaluated        theeffectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of the disclosurecontrols and procedures, as of the end of the period covered by this report basedon such evaluation; and |
|   |                                                                                                                                                                                                                                                                                                                             |   |
|   | 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 controlover financial reporting; and |
|   |                                                                                                                                                                                                                                                                                                                             |   |
| 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        auditorsand the audit committee of the registrant’s board of directors (or personsperforming the equivalent function): |
|   |                                                                                                                                                                                                                                                                                                                             |   |
|   | 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 to record, process, summarize and report financial information; and |
|   |                                                                                                                                                                                                                                                                                                                             |   |
|   | b)                                                                                                                                                                                                                                                                                                                               | Any fraud,        whether or not material, that involves management or other employees        who have a significantrole in the registrant’s internal control over financialreporting. |

 

| Date:    March          16, 2006 | /s/    | Matthew    H. Knight       |
|------------------------------------------------------|--------|----------------------------|
|                                                 |   |                            |
|                                                 |   | Matthew    H. Knight       |
|                                                 |   | Chief    Executive Officer |

----