TENTH AMENDMENT Dated as of October 31, 2005 to

Exhibit 10.1

TENTH AMENDMENT

Dated as of October 31, 2005

to

RECEIVABLES SALE AGREEMENT

Dated as of December 21, 2001

THIS TENTH AMENDMENT (the “Amendment”), dated as of October 31 2005, is entered into among PerkinElmer Receivables Company, as Seller (the “Seller”), PerkinElmer, Inc., as Initial Collection Agent (the “Initial Collection Agent,” and together with any successor thereto, the “Collection Agents”), the committed purchasers party thereto (the “Committed Purchasers”), Windmill Funding Corporation (“Windmill”), and ABN AMRO Bank N.V., as agent for the Purchasers (the “Agent”)

WITNESSETH:

WHEREAS, the Seller, the Initial Collection Agent, the Agent, the Committed Purchasers and Windmill have heretofore executed and delivered a Receivables Sale Agreement, dated as of December 21, 2001 (as amended, supplemented or otherwise modified through the date hereof, the “Sale Agreement”),

WHEREAS, the parties hereto desire to amend the Sale Agreement as provided herein;

NOW, THEREFORE, for good and valuable consideration, the receipt and adequacy of which are hereby acknowledged, the parties hereto hereby agree that the Sale Agreement shall be and is hereby amended as follows:

Section 1. The defined term “Credit Agreement” appearing in Schedule I to the Sale Agreement is hereby amended in its entirety and as so amended shall read as follows:

“Credit Agreement” means that certain $350,000,000 Credit Agreement dated as of October 31, 2005, as amended, among the Parent, the lenders from time to time party thereto, Bank of America, N.A., as Administrative Agent, Swing Line Lender, and L/C Issuer, Bank of America, N.A., Canadian Branch, as Canada Paying Agent, Bank of America, N.A., Singapore Branch, as Singapore Paying Agent, Bank of America, N.A., Tokyo Branch, as Yen Paying Agent, Citigroup Global Markets Inc. and HSBC Bank USA, National Association, as Co-Syndication Agents, ABN AMRO Bank N.V. and Deutsche Bank AG, as Co-Documentation Agents and Banc of America Securities LLC and Citigroup Global Markets Inc., as Joint Lead Arrangers and Joint Book Managers.

Section 2. The defined term “Intercreditor Agreement” appearing in Schedule I to the Sale Agreement is hereby deleted in its entirety.

Section 3. The defined term “Prime Rate” appearing in Schedule I to the Sale Agreement is hereby amended in its entirety and as so amended shall read as follows:

“Prime Rate” means, for any period, the daily average during such period of (a) the sum of (x) the greater of (i) the floating commercial loan rate per annum of ABN AMRO (which rate is a reference rate and does not necessarily represent the lowest or best rate actually charged to any customer by ABN AMRO) announced from time to time as its prime rate or equivalent for dollar loans in the USA, changing as and when said rate changes and (ii) the Federal Funds Rate plus 0.75% plus (y) the “Applicable Rate” then applicable to “Base Rate Loans” (each as defined in the Credit Agreement); provided, however, that during the pendency of a Termination Event, the “Applicable Rate” referred to above shall be 4.00%.

Section 4. Clause (m) of the defined term “Termination Event” appearing in Schedule I to the Sale Agreement is hereby deleted in its entirety.

Section 5. This Amendment shall become effective on the date the Agent has received (i) counterparts hereof executed by Seller, Initial Collection Agent, each Purchaser and the Agent and (ii) an executed Guarantor’s Acknowledgment and Consent.

Section 6. To induce the Agent and the Purchasers to enter into this Amendment, the Seller and Initial Collection Agent represent and warrant to the Agent and the Purchasers that: (a) the representations and warranties contained in the Transaction Documents, are true and correct in all material respects as of the date hereof with the same effect as though made on the date hereof (it being understood and agreed that any representation or warranty which by its terms is made as of a specified date shall be required to be true and correct in all material respects only as of such specified date); (b) no Potential Termination Event exists; (c) this Amendment has been duly authorized by all necessary corporate proceedings and duly executed and delivered by each of the Seller and the Initial Collection Agent, and the Sale Agreement, as amended by this Amendment, and each of the other Transaction Documents are the legal, valid and binding obligations of the Seller and the Initial Collection Agent, enforceable against the Seller and the Initial Collection Agent in accordance with their respective terms, except as enforceability may be limited by bankruptcy, insolvency or other similar laws of general application affecting the enforcement of creditors’ rights or by general principles of equity; and (d) no consent, approval, authorization, order, registration or qualification with any governmental authority is required for, and in the absence of which would adversely effect, the legal and valid execution and delivery or performance by the Seller or the Initial Collection Agent of this Amendment or the performance by the Seller or the Initial Collection Agent of the Sale Agreement, as amended by this Amendment, or any other Transaction Document to which they are a party.

Section 7. This Amendment may be executed in any number of counterparts and by the different parties on separate counterparts and each such counterpart shall be deemed to be an original, but all such counterparts shall together constitute but one and the same Amendment.

Section 8. Except as specifically provided above, the Sale Agreement and the other Transaction Documents shall remain in full force and effect and are hereby ratified and confirmed in all respects. Nothing herein shall be interpreted as permitting any Lien to be granted to any Person in the Receivables or any other property of the Originators or the Seller in which the Agent or any Purchaser has an interest under the Transaction Documents. The execution, delivery, and effectiveness of this Amendment shall not operate as a waiver of any right, power, or remedy of any Agent or any Purchaser under the Sale Agreement or any of the other Transaction Documents, nor constitute a waiver or modification of any provision of any of the other Transaction Documents. All defined terms used herein and not defined herein shall have the same meaning herein as in the Sale Agreement. The Seller agrees to pay on demand all costs and expenses (including reasonable fees and expenses of counsel) of or incurred by the Agent and each Purchaser Agent in connection with the negotiation, preparation, execution and delivery of this Amendment.

Section 9. This Amendment and the rights and obligations of the parties hereunder shall be construed in accordance with and be governed by the law of the State of Illinois.

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IN WITNESS WHEREOF, the parties have caused this Amendment to be executed and delivered by their duly authorized officers as of the date first above written.

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GUARANTOR’S ACKNOWLEDGMENT AND CONSENT

The undersigned, PerkinElmer, Inc., has heretofore executed and delivered the Limited Guaranty dated as of December 21, 2001 (the “Guaranty”) and hereby consents to the Amendment to the Sale Agreement as set forth above and confirms that the Guaranty and all of the undersigned’s obligations thereunder remain in full force and effect. The undersigned further agrees that the consent of the undersigned to any further amendments to the Sale Agreement shall not be required as a result of this consent having been obtained, except to the extent, if any, required by the Guaranty referred to above.