RELEASE AGREEMENT

Exhibit 10.25

September 19, 2006

VIA E-MAIL

Mr. Darrell Dubroc, CEO

Vanguard Synfuels, LLC

P.O. Box 399

Pollock, LA 71467

Gentlemen:

First South Farm Credit, ACA (“First South”) has considered the request to release the existing six individual guarantors (the “Guarantor”) for Vanguards loans, and accept a guarantee of Diametrics Medical, Inc. (“DMED”). This is to advise that First South agrees to release the (six individual) Guarantors provided all of the following conditions are met, satisfied, and delivered to First South, on or before 4:00 p.m. CDT, Friday, September 29, 2006.

(1) DMED acquires 100% of the membership/ownership interest in Vanguard Synfuels, LLC, and satisfactory evidence thereof is furnished to First South;

(2) First South is furnished with a copy of the Articles and By-Laws of DMED, as amended, to date, along with a certificate of good standing from the State of its incorporation;

(3) Furnish evidence satisfactory to First South, in its sole discretion, of the cash investment of $7,000,000.00 in equity in DMED;

(4) Furnish a certified resolution of the board of directors of DMED acknowledging that Vanguard is a 100% owned subsidiary of DMED and that it serves a legitimate business purpose for DMED to unconditionally and in solido (jointly and severally) with Vanguard, guarantee the timely payment and performance of all indebtedness and obligations of Vanguard to First South, which resolution would also authorize a duly designated (named) officer to execute the continuing guaranty agreement in the form of Exhibit “A” hereto (the “Guaranty”) for any and all of the present and/or future indebtedness and obligations of Vanguard to First South. First South would also need to be furnished with Vanguard’s Board of Managers/Directors consent resolution authorizing a named official to enter into the amendment to the loan agreement, under such terms and conditions as said official deems appropriate.

(5) DMED would execute and deliver the Guaranty to First South.

(6) Vanguard and First South would execute and deliver a First Amendment to Loan Agreement in the form of Exhibit ‘B’ attached hereto.

(7) Upon timely satisfaction of the above conditions, First South will promptly (within 2 business days) deliver to an agent for Vanguard, DMED and each of the Guarantors (“Agent”), as set forth in the First Amendment to Loan Agreement, the original of each of the existing Guarantors guaranty agreements, each marked “Cancelled and Released.” The delivery of the original guaranty agreements will be made by sending each of the six original guaranty agreements by U.S Certified Mail addressed to Agent as set forth in the First Amendment to Loan Agreement.

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First South’s agreement to release the existing Guarantors is further conditioned upon all of the documents, documentation and supporting evidence required above to be satisfactory in form and substance to First South, in its sole discretion, and Vanguard shall promptly (on or before September 29, 2006) pay all costs and expenses related to the negotiation of this agreement and finalizing the proposed transaction, including paying First South’s attorney fees of $3,000.00. Failure to timely pay said sums shall be an Event of Default under the Loan Agreement. Finally, this proposal will expire and terminate unless Vanguard and DMED both accept this proposal in writing and return their signed acceptance to First South or on before 4:00 p.m. CDT Wednesday, September 20, 2006. Fax or electronic signatures will be deemed acceptable as originals, and the acceptance may be executed in multiple counterparts.

EXHIBIT “A”

CONTINUING GUARANTY

In consideration of FIRST SOUTH FARM CREDIT, ACA (“Creditor”) making loans or advances or otherwise giving credit to the above named debtor (“Debtor”), as Creditor and Debtor may from time to time agree upon, the undersigned guarantor (“Guarantor”), does hereby unconditionally and in solido with Debtor, guarantee to Creditor, its successors and assigns, and all future holder or holders of this Continuing Guaranty, which is hereby declared to be transferable, the prompt payment of all debts, obligations, and liabilities, whether direct, indirect, absolute, contingent, secured, or unsecured, (hereinafter collectively referred to some times as “Obligations”) which Debtor may now or at any time, or times, hereafter owe, or be liable to pay to Creditor, and Guarantor agrees to pay the same promptly when due and at all times thereafter, without notice or demand. Should Debtor be or become insolvent, then Guarantor agrees to pay all Obligations forthwith whether then due or not due.

Creditor may sell, pledge, assign, discount, rediscount, surrender, compound, release, renew, extend, forebear, alter, exchange, or otherwise deal with and/or dispose of any and all property, securities, collateral, endorsements and guaranties now or hereafter held by said Creditor as security, indemnity, or otherwise, upon such terms and conditions as Creditor in its sole discretion may deem advisable, and Creditor may, from time to time, make such changes in, renewals and extensions of time, mode and terms of payment of said Obligations of Debtor, and of the time, mode and terms of payment of all or any endorsements and guaranties of said Obligations made by others, as Creditor in its sole discretion may deem advisable; all without in any way affecting, limiting, or prejudicing the Creditor’s rights or the Guarantor’s liability under this Continuing Guaranty. Creditor is hereby irrevocably authorized and empowered at any and all times to impute or apply, as it may see fit, any payment or payments which may be made by Debtor or by others on Debtor’s Obligations.