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                                                                   Exhibit 10.21

                       FIRST AMENDMENT TO CREDIT AGREEMENT

          This First Amendment to Credit Agreement is entered into as of July
14, 1999, by and between Spectrum Laboratories, Inc., a Delaware corporation
("Borrower") and City National Bank, a national banking association ("CNB").

                                    RECITALS

          A. Borrower and CNB are parties to that certain Credit Agreement dated
as of December 22, 1998 (hereinafter the "Credit Agreement").

          B. Borrower and CNB desire to supplement and amend the Credit
Agreement as hereinafter set forth. NOW, THEREFORE, the parties agree as
follows:

1.            DEFINITIONS. Capitalized terms used in this Amendment without
              definition shall have the meanings set forth in the Credit
              Agreement.

2.            AMENDMENTS. The Credit Agreement is amended as follows:

              2.1       The following new definitions are added to Section 1 of
                        the Credit Agreement:

                        "CD COLLATERAL" means the time deposits owned by Roy
                        Eddleman and/or Borrower which are maintained at CNB and
                        pledged as collateral securing the Obligations.

                        "CD RATE" means the interest rate from time to time in
                        effect on the CD Collateral; provided, however, if there
                        is more than one rate, the CD Rate shall be the highest
                        of such rates.

                        "NET INCOME" shall be determined on a consolidated basis
                        for Borrower and the Subsidiaries and shall mean net
                        income after taxes determined in accordance with GAAP.

              2.2       The definition of "Cash/Securities Collateral" is
                        deleted from Section 1 of the Credit Agreement, and the
                        term CD Collateral will be substituted for the term
                        Cash/Securities Collateral everywhere else that the term
                        Cash/Securities Collateral appears in the Credit
                        Agreement.

              2.3       The definitions of "Cash Flow from Operations" and
                        "Tangible Net Worth" are amended in their entirety to
                        provide as follows:

                        "CASH FLOW FROM OPERATIONS" will be determined on a
                        consolidated basis for Borrower and the Subsidiaries and
                        means the sum of (a) net income after taxes and before
                        extraordinary items in accordance with GAAP earned over
                        the twelve month period ending on the date of
                        determination, PLUS (b) amortization of intangible
                        assets, PLUS (c) interest expense, PLUS (d) depreciation
                        expensed during the twelve month period ending on the
                        date of determination, PLUS the amount of "compensation
                        expense related to stock options" expensed during the
                        twelve-month period ending on the date of determination,
                        which expense is reflected as an increase in Borrower's
                        stockholders' equity, as shown on Borrower's financial
                        statements delivered to CNB pursuant to the terms of
                        this Agreement.

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                        "TANGIBLE NET WORTH" means the total of all assets
                        appearing on a balance sheet prepared in accordance with
                        GAAP for Borrower and the Subsidiaries on a consolidated
                        basis, MINUS (a) all intangible assets, including,
                        without limitation, unamortized debt discount,
                        Affiliate, employee and officer receivables or advances,
                        goodwill, research and development costs, patents,
                        trademarks, the excess of purchase price over underlying
                        values of acquired companies, any covenants not to
                        compete, deferred charges (other than current prepaid
                        expenses and deferred taxes), copyrights, franchises,
                        art works and appraisal surplus; MINUS (b) all
                        obligations which are required by GAAP to be reflected
                        as a liability on the consolidated balance sheet of
                        Borrower and the Subsidiaries; MINUS (c) the amount, if
                        any, at which shares of stock of a non-wholly owned
                        Subsidiary appear on the asset side of Borrower's
                        consolidated balance sheet, as determined in accordance
                        with GAAP; MINUS (d) minority interests; MINUS (e)
                        deferred income and reserves not otherwise reflected as
                        a liability on the consolidated balance sheet of
                        Borrower and the Subsidiaries; PLUS (f) CD Collateral.

              2.4       The first sentence of Section 2.1.1 is stricken and
                        replaced with the following:

                        "Effective on the later to occur of the date of the
                        First Amendment, or the date on which Roy T. Eddleman
                        opens at CNB one or more time deposits to evidence CD
                        Collateral in an amount not less than $843,000.00, the
                        Term Loan A will bear interest until due (whether at
                        stated maturity, by acceleration or otherwise) at a rate
                        equal to (a) the CD Rate plus one percent (1.0%) per
                        annum on that portion of the outstanding principal
                        amount of the Term Loan A equal to the principal amount
                        of the CD Collateral, and (b) nine and 14/100 percent
                        (9.14%) per annum on that portion of the outstanding
                        principal amount of the Term Loan A in excess of the
                        principal amount of the CD Collateral, subject to the
                        provisions in CNB's Yield Maintenance Agreement, a copy
                        of which is attached as Exhibit "C", the terms of which
                        shall only apply to a prepayment on the principal amount
                        in excess of the CD Collateral."

              2.5       Section 2.2 is stricken and replaced with the following:

                        2.2 THE TERM LOAN B. CNB agrees to make, upon Borrower's
                        request, a term loan ("Term Loan B") to Borrower in the
                        principal amount of Two Hundred Seventy Five Thousand
                        Four Hundred Sixty Five and 44/100 Dollars
                        ($275,465.44). The Term Loan B will be evidenced by a
                        promissory note ("Term Note") in the form attached
                        hereto as Exhibit "B". or as superseded in any amendment
                        to this Agreement.

                              2.2.1 INTEREST ON TERM LOAN B. The Term Loan B
                        will bear interest from disbursement until due (whether
                        at stated maturity, by acceleration or otherwise) at a
                        fluctuating rate equal to the Prime Rate plus
                        one-quarter of one percent (0.25%) per annum. Interest
                        will be payable monthly in arrears on the first day of
                        each month, starting on August 1, 1999, and on the date
                        the Term Loan B is paid in full.

                              2.2.2 PAYMENT OF TERM LOAN B. The principal amount
                        of the Term Loan B will be repaid by Borrower to CNB in
                        twelve (12)

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                        consecutive monthly installments, consisting of eleven
                        (11) installments each in the amount of $8,530.00, and a
                        final installment in the amount of $181,635.44,
                        commencing on August 1, 1999, and continuing on the
                        first day of each month up to and including July 1,
                        2000, on which date all principal and accrued interest
                        will be due and payable in full.

              2.6       Section 2.7 is stricken and replaced with the following:

                        "2.7 CD COLLATERAL. Borrower agrees that the aggregate
                        principal amount of the CD Collateral shall at no time
                        be less than $943,000.00, of which $843,000.00 shall be
                        pledged by Roy T. Eddleman; provided, however, CNB
                        agrees to release (a) $250,000.00 of the principal
                        amount of the CD Collateral pledged by Roy T. Eddleman
                        ("Eddleman CD Collateral") if Borrower is in compliance
                        with Section 5.10 of this Agreement as determined by CNB
                        from Borrower's financial statements for its fiscal
                        quarter ending July 3, 1999 delivered to CNB pursuant to
                        the terms of this Agreement and no Event of Default
                        exists hereunder at the time of such release, and (b) an
                        additional $250,000.00 of the principal amount of the
                        Eddleman CD Collateral if Borrower is in compliance with
                        Section 5.10 of this Agreement as determined by CNB from
                        Borrower's financial statements for its fiscal quarter
                        ending October 3, 1999 delivered to CNB pursuant to the
                        terms of this Agreement and no Event of Default exists
                        hereunder at the time of such release. If concurrently
                        with CNB's release of the Eddleman CD Collateral as
                        provided in this Section 2.7, the principal amount of
                        the released CD Collateral is used to prepay the
                        principal amount of Term Loan A, the prepayment charge
                        set forth in CNB's Yield Maintenance Agreement shall not
                        apply to such prepaid principal amount."

              2.7       Section 5.10 is stricken and replaced with the
                        following:

                        "5.10 FINANCIAL TESTS. Borrower shall maintain:

                              5.10.1 Tangible Net Worth plus Subordinated Debt
                        plus SLI Acquisition Corp. Preferred Stock of not less
                        than $2,500,000.00;

                              5.10.2 A ratio of Total Senior Liabilities to
                        Tangible Net Worth plus Subordinated Debt of not more
                        than 2.5 to 1 at all times;

                              5.10.3 A ratio of Cash Flow from Operations to
                        Debt Service of not less than 1.25 to 1 during the
                        twelve months preceding the date of determination;

                              5.10.4 Net Income of not less than $400,000.00 for
                        Borrower's' fiscal year ending; and

                              5.10.5 Net Income of not less than $1.00 for each
                        of Borrower's fiscal quarters."

              2.8       Section 7.1.9 is stricken and replaced with the
                        following:

                        "7.1.9 Roy T. Eddleman fails to maintain verifiable
                        Liquid Assets including CD Collateral of at least
                        $1,500,000.00."

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              2.9       Exhibit "B" currently attached to the Credit Agreement
                        is superseded and replaced with Exhibit "B" attached to
                        this Amendment.

3.            EXISTING AGREEMENT. Except as expressly amended herein, the Credit
              Agreement shall remain in full force and effect, and in all other
              respects is affirmed.

4.            CONDITIONS PRECEDENT. This Amendment shall become effective upon
              the fulfillment of all of the following conditions to CNB's
              satisfaction:

              4.1       CNB shall have received this Amendment duly executed by
                        Borrower and acknowledged by the Guarantors;

              4.2       CNB shall have received a new Term Loan B in the form
                        attached as Exhibit "B" to this Amendment, duly executed
                        by Borrower;

              4.3       Roy T. Eddleman has opened one or more time deposits at
                        CNB to evidence CD Collateral in an amount not less than
                        $843,000.00 and CNB shall have received a pledge
                        agreement, duly executed by Roy T. Eddleman, pursuant to
                        which Roy T. Eddleman will pledge to CNB as collateral
                        for the Obligations CD Collateral in the foregoing
                        amount; and

              4.4       All other documents and legal matters in connection with
                        the transactions described in the Agreement will be
                        satisfactory in form and substance to CNB

5.            COUNTERPARTS. This Amendment may be executed in any number of
              counterparts, and all such counterparts taken together shall be
              deemed to constitute one and the same instrument.

6.            GOVERNING LAW. This Amendment and the rights and obligations of
              the parties hereto shall be construed in accordance with, and
              governed by the laws of the State of California.

IN WITNESS WHEREOF, the parties have executed this Amendment as of the day and
year first above written.

"Borrower"                           Spectrum Laboratories, Inc., a
                                     Delaware corporation


                                     By: /s/ Roy T. Eddleman
                                        -------------------------------------
                                        Roy T. Eddleman, Chief Executive Officer


 "CNB"                               City National Bank, a national
                                     banking association

                                     By: /s/ Richard Fein
                                        ----------------------------------------
                                        Richard Fein, Vice President


[Consent of Guarantors continued on next page]



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[Consent of Guarantors continued from prior page]



CONSENT OF GUARANTORS:

          The undersigned have previously guaranteed the indebtedness of
SPECTRUM LABORATORIES, INC. owed to CNB. The undersigned confirm that their
respective guaranties and the security given in connection therewith, if any,
shall continue in full force and effect and that each such guaranty shall be a
separate and distinct obligation and apply to the indebtedness arising from the
Credit Agreement as amended herein, subject to the overall limitation as to the
amount guaranteed.

/s/ Roy T. Eddleman
-----------------------------
Roy T. Eddleman


Spectrum Europe B.V., a                  Hydro-med Products, Inc., a
Netherlands company                      Texas Corporation


By: /s/ Roy T. Eddleman                  By: /s/ Roy T. Eddleman
   -----------------------------            --------------------------------

Its: CEO                                 Its: CEO
   -----------------------------            --------------------------------


SLI Acquisition Corp., a                 Spectrum Molecular Separations, Inc., a
Delaware corporation                     Delaware corporation

By: /s/ Roy T. Eddleman                  By: /s/ Roy T. Eddleman
   -----------------------------            --------------------------------

Its:  CEO                                Its:  CEO
   -----------------------------            --------------------------------



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                                   TERM NOTE B
                               (ANY INTEREST RATE)
$275,465.44                                                   Irvine, California
                                                                   July 14, 1999


          FOR VALUE RECEIVED, the undersigned, SPECTRUM LABORATORIES, INC., a
Delaware corporation ("Borrower"), promises to pay to the order of CITY NATIONAL
BANK, a national banking association ("CNB"), at its Office located at 9
Executive Circle, Irvine, California 92614 the principal amount of TWO HUNDRED
SEVENTY FIVE THOUSAND FOUR HUNDRED SIXTY FIVE AND 44/100 DOLLARS ($275,465.44),
plus interest on the unpaid principal balance, computed on the basis of a
360-day year, actual days elapsed, at the rates, times and in accordance with
the terms of that certain Credit Agreement between Borrower and CNB, dated as of
December 22, 1998, as may be amended from time to time (the "Credit Agreement").
Principal is payable in twelve (12) consecutive monthly installments, consisting
of eleven (11) installments each in the amount of $8,530.00, and a final
installment in the amount of $181,635.44. commencing August 1, 1999, and
continuing on the first day of each month up to and including July 1, 2000, on
which day the balance of principal and interest thereon unpaid shall become due
and payable. Capitalized terms not defined herein will have the meanings given
them in the Credit Agreement.

         If payment on this Note becomes due and payable on a non-business day,
the maturity thereof shall be extended to the next business day and, with
respect to payments of principal or interest thereon, shall be payable during
such extension at the then applicable rate. Upon the occurrence of one or more
of the Events of Default specified in the Credit Agreement, all amounts
remaining unpaid on this Term Note may become or be declared to be immediately
payable as provided in the Credit Agreement. without presentment, demand or
notice of dishonor, all of which are expressly waived. Borrower agrees to pay
all costs of collection of this Note and reasonable attorneys' fees (including
attorneys' fees allocable to CNB's in-house counsel) in connection therewith,
irrespective of whether suit is brought thereon.

         This is the Term Note B referred to in the Credit Agreement and is
entitled to the benefits thereof, and supersedes and replaces in its entirety
that certain Term Note B dated December 22, 1998 in the original principal sum
of $326,645.44 executed by Borrower in favor of CNB.

         Upon CNB's written notice to Borrower of the occurrence of an Event of
Default, the outstanding principal balance (and interest, to the extent
permitted by law) shall bear additional interest from the date of such notice at
the rate of Five Percent (5.0%) per annum higher than the interest rate as
determined and computed above, and continuing thereafter until the Event of
Default is cured.

         This Note shall be governed by the laws of the State of California. If
this Note is executed by more than one Borrower, all obligations are joint and
several.


`BORROWER"                         Spectrum Laboratories, Inc., a
                                   Delaware corporation


                                   By:  /s/ Roy T. Eddleman
                                        ----------------------------------------
                                        Roy T. Eddleman, Chief Executive Officer