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                                                                   Exhibit 4(xi)
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                         PLEDGE AND SECURITY AGREEMENT


     This PLEDGE AND SECURITY AGREEMENT is made and entered into effective as of
October 31, 2001, by Enviro-Clean of America, Inc., a Nevada corporation, the
principal place of business of which is located at 1023 Morales Street, San
Antonio, Texas 78207 ("Debtor"), in favor of Randall K. Davis, an individual,
who has been appointed Agent and Attorney-In-Fact for certain purchasers of the
Debtor's promissory notes and whose principal place of business is located at
1023 Morales Street, San Antonio, Texas 78207 ("Secured Party").

                                   Recitals

          WHEREAS, Debtor holds title to certain shares of common stock, par
     value $0.01 (the "Common Stock"), of IVAX Diagnostics, Inc., a Delaware
     Corporation (the "Company");

          WHEREAS, from time to time before, on and after the effective date of
     this Security Agreement, Debtor will issue promissory notes to private
     investors (all such notes, whenever created or issued being referred to
     herein as the "Investor Notes") in a private offering pursuant to that
     certain private placement memorandum dated August 23, 2001 (the
     "Offering");

          WHEREAS, Debtor has agreed to grant a security interest in certain
     shares of Common Stock of the Company in favor of the private investors in
     order to secure the payment of all Investor Notes whenever issued; and

          WHEREAS, Secured Party has been appointed by the private investors to
     act as their sole Agent and Attorney-in-Fact in all matters pertaining to
     the security interest in the Collateral pursuant to that certain agency
     agreement among the holders of the Investor Notes, Secured Party as agent
     for the holders of the Investor Notes, and Debtor (the "Agency Agreement").
     This Agreement, the Agency Agreement, the Investor Notes, the Escrow
     Agreement (as defined below) and all other documents and instruments
     executed in connection herewith or therewith, are collectively referred to
     as the "Offering Documents."

     NOW, THEREFORE, in consideration of the purchase of the Investor Notes by
the private investors, the premises and the agreements herein contained, and
other good and valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, Debtor and Secured Party hereby agree as follows:

     1. Pledge of Stock and Creation of Security Interest.  To secure the timely
payment and performance of the Secured Obligations (as defined below), Debtor
hereby collaterally assigns and pledges to Secured Party, and grants to Secured
Party a security interest in, all the right, title and interest of Debtor, now
owned or hereafter acquired, in, to and under the

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collateral described in Section 2 herein below, and the proceeds thereof (the
"Collateral"). The Collateral shall be held in escrow pursuant to the terms of
an Escrow Agreement between Debtor, Secured Party and the Escrow Agent named
therein (the "Escrow Agent") of even date herewith (the "Escrow Agreement")
until such time as all amounts due under the Offering Documents have been paid
in full.

     2. Collateral.  The Collateral shall consist of unencumbered shares of
Common Stock of the Company held by Debtor and set aside for escrow, which
number of shares shall be no less than an amount with a Fair Market Value (as
defined below) equal to or greater than 125% of the aggregate total of the face
value of the outstanding Investor Notes (the "Outstanding Note Amount"). The
amount of Common Stock escrowed as Collateral under this Agreement shall be
automatically adjusted by the Escrow Agent on a quarterly basis during the term
of the Investor Notes, on January 1, April 1, July 1 and October 1 (the "Value
Review Dates"), pursuant to the Escrow Agreement. Within three (3) days of any
Value Review Date, if the Fair Market Value of the escrowed Common Stock is in
excess of 125% of the Outstanding Note Amount (the "Excess Amount"), the Company
may request from the Escrow Agent, and the Escrow Agent must deliver to the
Company if so requested, any shares of Common Stock whose total value does not
exceed the Excess Amount. Within three (3) days of any Value Review Date, if the
Fair Market Value of the escrowed Common Stock is less than 125% of the
Outstanding Note Amount (the "Deficit Amount") the Company must deliver to the
Escrow Agent, within three (3) business days, additional shares of Common Stock
of the Company, equal to or more than the Deficit Amount. If, following the date
hereof, there occurs any stock dividend, stock split, recapitalization or other
change affecting the Common Stock of the Company as a class effected without
receipt of consideration, any new, substituted or additional securities or other
property that is by reason of such transaction distributed with respect to
Common Stock of the Company that comprises the Collateral shall be immediately
delivered by Debtor to Secured Party to be held as Collateral, until adjusted on
a Value Review Date. If, following the date hereof, there occurs any dividend,
distribution, merger, consolidation, share exchange or reorganization affecting
the Common Stock of the Company, then any new, substituted or additional
securities or other property (including money paid as a regular cash dividend)
that is by reason of such transaction distributed with respect to the Collateral
shall be immediately delivered by Debtor to Secured Party to be held as
Collateral, until adjusted on a Value Review Date. In the event any cash is
deposited as part of the Collateral pursuant hereto, the parties will make
appropriate amendments to this Agreement to include investment provisions and
controls for such cash.

     The "Fair Market Value" per share of Common Stock of the Company shall be
equal to the average of the closing price per share of Common Stock of the
Company as reported by The American Stock Exchange or such other securities
exchange, market or quotation system on which Common Stock of the Company is
then listed for trading or quoted on each of the ten (10) trading days prior to
the date of purchase.

     The Debtor shall deliver the Collateral to Secured Party by delivering the
Collateral, together with stock powers executed in blank, to Randall K. Davis as
Escrow Agent, 1023 Morales Street, San Antonio, Texas 78207, or to such other
person or address as shall be designated by the Holders of the Investor Notes
pursuant to the Escrow Agreement.

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     3. Secured Obligations of Debtor. The Collateral secures and shall
hereafter secure (i) the Payment by Debtor to Secured Party of all indebtedness
now or hereafter owed pursuant to the Offering Documents to Secured Party by
Debtor, including, without limitation, the loan made to Debtor pursuant to the
Investor Notes, together with any interest thereon and extensions, modifications
and renewals thereof, (ii) the payment by Debtor, or reimbursement to Secured
Party, of all fees, costs or expenses to be paid, incurred or borne by Debtor
pursuant to any of the Offering Documents, and (iii) the performance by Debtor
of all other obligations and the discharge of all other liabilities to Secured
Party of every kind and character, direct or indirect, absolute or contingent,
due or to become due, now existing or hereafter arising under this Agreement or
any of the other Offering Documents (the foregoing are collectively referred to
as the "Secured Obligations"). All payments and performance shall be in
accordance with the terms of the Offering Documents. Debtor shall reimburse
Secured Party on demand for any and all amounts expended by Secured Party in
accordance with, or in the enforcement (judicially or otherwise) or exercise of
its rights under, the terms of this Agreement, including attorneys' fees, which
amounts are included in the Secured Obligations secured hereunder.

     4. Debtor's Representations and Warranties.

     Debtor represents and warrants that:

     (a) Debtor is (or to the extent that this Agreement states that the
         Collateral is to be acquired after the date hereof, will be) the sole
         owner of the Collateral; upon delivery of the Collateral to Secured
         Party the security interest hereunder in the Collateral will be a
         first, prior and perfected security interest; there are no security
         interests, liens or encumbrances, or adverse claims of title to,
         community property interests in, or any other interest whatsoever in,
         the Collateral or any portion thereof except that created by this
         Agreement; and no financing statement, mortgage or deed of trust
         covering the Collateral or any portion thereof exists or is on file in
         any public office; and

     (b) Debtor has the full power and authority to pledge, transfer and assign
         the Collateral to Secured Party, and such pledge, transfer and
         assignment to Secured Party will not violate any federal or state law,
         rule or regulation, including without limitation federal or state
         securities laws; and

     (c) No part of the Collateral is subject to a risk of forfeiture or
         vesting provisions applicable to Debtor pursuant to the terms of the
         instrument pursuant to which Debtor acquired the Collateral; and

     (d) Neither the execution and delivery of this Agreement by Debtor nor the
         consummation of the transactions herein contemplated nor the
         fulfillment of the terms hereof will result in a breach of any of the
         terms or provisions of, or constitute a default under, or constitute an
         event which with notice or lapse of time or both will result in a
         breach of or constitute a default under, any material agreement,
         indenture, mortgage, deed of trust, equipment lease or other instrument
         to which Debtor is a party, or conflict with any law, order, rule or
         regulation applicable to Debtor of any

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         court or any federal or state government, regulatory body or
         administrative agency, or any other governmental body having
         jurisdiction over Debtor or Debtor's properties.

     (e) Debtor is a corporation duly organized, legally existing and in good
         standing under the laws of the state of Nevada.

     5. Covenants of Debtor.

     Debtor covenants that:

     (a) Debtor will defend the Collateral against all claims and demands of
         all third parties at any time claiming the same or any interest
         therein;

     (b) Debtor will, promptly upon request by Secured Party, procure or
         execute and deliver any document, give any notices, execute and file
         any financing statements, mortgages or other documents, all in form and
         substance satisfactory to Secured Party, mark any chattel paper,
         deliver any chattel paper or instruments to Secured Party and take any
         other actions which are necessary or, in the judgment of Secured Party,
         desirable to perfect or continue the perfection and first priority of
         Secured Party's security interest in the Collateral, to protect the
         Collateral against the rights, claims, or interests of third persons or
         to effect the purposes of this Agreement, and will pay all costs
         incurred in connection therewith;

     (c) Debtor will not, without the prior written consent of Secured Party,
         in any way hypothecate or create or permit to exist any lien, security
         interest or encumbrance on or other interest in the Collateral except
         that created by this Agreement, nor will Debtor sell, transfer, assign,
         exchange or otherwise dispose of the Collateral or any option with
         respect thereto. If the Collateral, or any part thereof, is sold,
         transferred, assigned, exchanged, or otherwise disposed of in violation
         of these provisions, the security interest of Secured Party shall
         continue in such Collateral or part thereof notwithstanding such sale,
         transfer, assignment, exchange or other disposition, and Debtor will
         hold the proceeds thereof in a separate account for Secured Party's
         benefit. Debtor will, at Secured Party's request, transfer such
         proceeds to Secured Party in kind;

     (d) Debtor will pay and discharge all taxes, assessments and governmental
         charges or levies against the Collateral prior to delinquency thereof
         and will keep the Collateral free of all unpaid charges whatsoever; and

     (e) Secured Party shall have the right to make any payments and do any
         other acts Secured Party may deem necessary to protect its security
         interest in the Collateral, including, without limitation, the rights
         to pay, purchase, contest or compromise any encumbrance, charge or lien
         which in the judgment of Secured Party appears to be prior to or
         superior to the security interest granted hereunder, and appear in and
         defend any action or proceeding purporting to affect its security
         interest in and/or the value of the Collateral, and in exercising any
         such powers or authority, the right to pay all expenses incurred in
         connection therewith, including attorneys' fees. Debtor hereby

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         agrees to reimburse Secured Party for all payments made and expenses
         incurred, which amounts shall be secured under this Agreement, and
         agrees it shall be bound by any payment made or act taken by Secured
         Party hereunder. Secured Party shall have no obligation to make any of
         the foregoing payments or perform any of the foregoing acts.

     6. Defaults and Remedies. Upon the occurrence and during the continuation
of an Event of Default (as described and defined in the Investor Notes), Secured
Party may, at its option, without notice to or demand upon Debtor, do any one or
more of the following:

     (a) Declare all advances made by Secured Party to Debtor under the Note
         and all other Secured Obligations to be immediately due and payable,
         whereupon all unpaid principal and interest on all advances and other
         Secured Obligations shall become and be immediately due and payable;

     (b) Exercise any or all of the rights and remedies provided for by the
         applicable Uniform Commercial Code, specifically including, without
         limitation, the right to recover the attorneys' fees and other expenses
         incurred by Secured Party in the enforcement of this Agreement or in
         connection with Debtor's redemption of the Collateral;

     (c) Sell all or any portion of the Collateral in any commercially
         reasonable manner in any one or more public or private sales, at the
         sole discretion of Secured Party, or proceed by an action or actions at
         law or in equity to recover the Secured Obligations. Debtor agrees that
         any sale of all or any portion of the Collateral in the public market,
         in compliance with applicable federal and state securities laws and
         regulations, shall be conclusively presumed to be commercially
         reasonable. Secured Party shall also have the right and option to
         purchase all or any portion of the Collateral from Debtor at a price
         equal to the Fair Market Value of such Collateral. Any consideration
         owed to Debtor for any such purchase shall be first offset against the
         Secured Obligations, with any excess consideration to be paid in cash
         to Debtor; and

     (d) Enforce one or more remedies hereunder, successively or concurrently,
         and such action shall not operate to estop or prevent Secured Party
         from pursuing any other or further remedy which it may have, and any
         repossession or retaking or sale of the Collateral pursuant to the
         terms hereof shall not operate to release Debtor until full and final
         payment of any deficiency has been made in cash. Debtor shall reimburse
         Secured Party upon demand for, or Secured Party may apply any proceeds
         of Collateral to, the costs and expenses (including attorneys' fees,
         transfer taxes and any other charges) incurred by Secured Party in
         connection with any sale, disposition or retention of any Collateral
         hereunder.

     7. Miscellaneous Provisions.

     (a) Notices. Any and all notices required by this Agreement shall be
         delivered or sent in the manner and to the addresses set forth in the
         Agency Agreement.

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     (b) Headings. The various headings in this Agreement are inserted for
         convenience only and shall not affect the meaning or interpretation of
         this Agreement or any provision hereof.

     (c) Governing Law. This Agreement shall be construed in accordance with
         and all disputes hereunder shall be governed by the internal laws of
         the State of Texas without regard to principles of conflicts of laws.

     (d) No Waiver; Amendments. No delay in enforcing or failure to enforce any
         right under this Agreement by Secured Party shall constitute a waiver
         by Secured Party of such right. No waiver by Secured Party of any
         default hereunder shall be effective unless in writing, nor shall any
         waiver operate as a waiver of any other default or of the same default
         on a future occasion. This Agreement or any provision hereof may be
         changed, waived or terminated only by a statement in writing signed by
         the party against which such change, waiver or termination is sought to
         be enforced.

     (e) Time of the Essence. Time is of the essence of each provision of this
         Agreement of which time is an element.

     (f) Binding Agreement. All rights of Secured Party hereunder shall inure
         to the benefit of its successors and assigns. Debtor shall not assign
         any of its interest under this Agreement without the prior written
         consent of Secured Party. Any purported assignment inconsistent with
         this provision shall, at the option of Secured Party, be null and void.

     (g) Entire Agreement. This Agreement, together with the Note and any other
         agreement executed in connection herewith, is intended by the parties
         as a final expression of their agreement and is intended as a complete
         and exclusive statement of the terms and conditions thereof.

     (h) Attorneys' Fees. In any action or proceeding brought to enforce any
         provision of this Agreement, or to seek damages for a breach of any
         provision hereof, the successful party shall be entitled to recover
         reasonable attorneys' fees in addition to any other available remedy.

     (i) Severability. If any provision of this Agreement should be found to be
         invalid or unenforceable, all of the other provisions shall nonetheless
         remain in full force and effect to the maximum extent permitted by law.

     (j) Survival of Provisions. All representations, warranties and covenants
         of Debtor contained herein shall survive the execution and delivery of
         this Agreement, and shall terminate only upon the full and final
         payment and performance by Debtor of the Secured Obligations.

     (k) Setoff. Secured Party shall have the right, at any time, to set off
         any indebtedness or obligation of Debtor under the Investor Notes
         against any indebtedness or obligation

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         of Secured Party, without notice to or demand upon Debtor and whether
         or not any such indebtedness or obligations are liquidated or mature at
         the time of such offset. Secured Party's right of offset hereunder
         shall be in addition to and not in limitation of any other rights or
         remedies which may exist in favor of Secured Party.

     (l) Power of Attorney. Debtor hereby appoints and constitutes Secured
         Party as Debtor's attorney-in-fact, effective upon the occurrence of
         and during the continuation of an Event of Default (as defined in the
         Note), for purposes of (i) collecting accounts or proceeds of any
         Collateral, (ii) conveying any item of Collateral to any purchaser
         thereof, and (iii) making any payments or taking any acts under Section
         5(e) hereof. Secured Party's authority hereunder shall include, without
         limitation, the authority to endorse and negotiate, for Secured Party's
         own account, any checks or instruments in the name of Debtor, to
         execute any receipt for any certificate of ownership or any document,
         to transfer title to any item of Collateral, and to take any other
         actions necessary or incident to the powers granted to Secured Party in
         this Agreement. This power of attorney is coupled with an interest and
         is irrevocable by Debtor until full and final payment of all of the
         Secured Obligations.

     (m) Authority of Secured Party. Secured Party shall have and be entitled
         to exercise all powers hereunder which are specifically delegated to
         Secured Party by the terms hereof, together with such powers as are
         reasonably incident thereto. Secured Party may perform any of its
         duties hereunder or in connection with the Collateral by or through
         agents or employees and shall be entitled to retain counsel and to act
         in reliance upon the advice of counsel concerning all such matters.
         Neither Secured Party nor any director, officer, employee, attorney or
         agent of Secured Party shall be liable to Debtor for any action taken
         or omitted to be taken by it or them hereunder, except for its or their
         own willful misconduct; nor shall Secured Party be responsible for the
         validity, effectiveness or sufficiency hereof or of any document or
         security furnished pursuant hereto. Secured Party and they shall be
         entitled to rely on any communication, instrument or document believed
         by it or them to be genuine and correct and to have been signed or sent
         by the proper person or persons. Debtor agrees to indemnify and hold
         harmless Secured Party and/or any such other person from and against
         any and all costs, expenses (including attorneys' fees), claims or
         liability incurred by Secured Party or such person hereunder, unless
         such claim or liability shall be due to willful misconduct on the part
         of Secured Party or such person.

     (n) Statute of Limitations. Debtor hereby waives the right to plead any
         statute of limitations as a defense to any obligation hereunder or any
         of the Secured Obligations to the full extent permitted by law.

     (o) Counterparts. This Agreement may be executed in one or more
         counterparts, each of which shall be deemed an original but all of
         which shall together constitute one and the same agreement.

     (p) Termination of the Agreement. This Agreement shall terminate upon full
         and final payment and performance of all of the Secured Obligations. At
         such time, Secured

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         Party shall reassign and redeliver to Debtor all of the Collateral
         hereunder which has not been sold, disposed of, retained or applied by
         Secured Party in accordance with the terms hereof. Such reassignment
         and redelivery shall be without warranty by or recourse to Secured
         Party (provided that such Collateral shall not be transferred or
         encumbered by Secured Party except as permitted under the Investor
         Notes) and shall be at the sole expense of Debtor.


                          [Signature Page to Follow]

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                    [Signature Page To Security Agreement]

     IN WITNESS HEREOF, a duly authorized and acting officer of Debtor has
executed this instrument in the name and on behalf of Debtor as of the date
first above written.

                              DEBTOR:

                              ENVIRO-CLEAN OF AMERICA, INC.



                              By:   /s/ Randall K. Davis
                                  ---------------------------------------
                                  Randall K. Davis, President

                              SECURED PARTY:


                                      /s/ Randall K. Davis
                                  ---------------------------------------
                                  Randall K. Davis, Agent and Attorney-In-Fact

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