Exhibit 10.2



               FIRST AMENDMENT TO AGREEMENT DATED AUGUST 3, 1999


         Amendment dated as of September 3, 1999 (this "Amendment") to the
Agreement dated August 3, 1999 (the "Agreement") among Medtech Diagnostics, Inc.
("Medtech"), AbTech Industries, Inc. ("AbTech") and Catalyst Financial Corp.

         WHEREAS, the parties desire to amend certain provisions of the
Agreement, and to confirm the continuing effectiveness of the Agreement as so
amended,

         NOW, THEREFORE, in consideration of the foregoing, and the mutual terms
and provisions hereinbelow set forth, it is agreed, as follows:

         1. Modification of Indebtedness Reduction Provisions. In order to allow
AbTech the ability to borrow additional funds to meet working capital needs up
to the date of the Initial Closing, Section 1(a) is amended to read as follows:

                           (a) AbTech will reduce its outstanding indebtedness,
         exclusive of its accounts payable, accrued liabilities, capital leases
         and the note due to HGI to not more that $300,000 by converting such
         indebtedness into not more than 775,000 shares of its common stock (the
         "Debt Conversion"). In addition to the $300,000 of outstanding
         indebtedness described above, AbTech shall be entitled to incur
         additional bridge-loan debt of up to $225,000, excluding any loans made
         to AbTech by Med Tech pursuant to Section 4 hereof, for purposes of
         meeting AbTech's working capital needs through the date of the Initial
         Closing(as defined herein).

         2. Modification of Interim Financing Provisions. In recognition of the
fact that Medtech has made two loans to AbTech in the respective principal
amounts of $150,000 and $20,000, instead of one $150,000 loan, as contemplated
by the provisions of Section 4(a) of the Agreement, said section is hereby
amended to read, as follows:

                           "(a) In order to assist AbTech in meeting its
         obligations prior to the Merger, Medtech has made two loans to AbTech
         in the respective principal amounts of $150,000 and $20,000. Such loans
         (i) are unsecured; (ii) are to be used by AbTech as working capital;
         (iii) bear interest at the rate of 10% per annum; and (iv) shall be
         cancelled upon consummation of the Merger, or if the Merger is not
         consummated on or before March 31, 2000, such loans shall mature on
         said date."

             3. Extension of Deadline for Completion of Debt Conversion. Section
4(b) of the Agreement is hereby amended to read, as follows:

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                           "(b) Anything contained in Section 4(a) to the
         contrary notwithstanding, (i) in the event that AbTech does not
         successfully complete the Debt Conversion on or before September 17,
         1999, the unpaid principal amount of said loan, together with all
         accrued, but unpaid interest thereon, shall become due and payable on
         September 24, 1999 without further notice or action required on the
         part of Medtech or the Placement Agent; and (ii) in the events that
         AbTech successfully completes the Debt Conversion on or before
         September 17, 1999, but (A) refuses to execute, for any reason, the
         Merger Agreement after it has been executed by Medtech; and/or (B)
         terminates the Offering after such loan has been made and prior to the
         Initial Closing, the unpaid principal amount of said loan, together
         with all accrued, but unpaid interest thereon, and a break-up fee
         payable to the Placement Agent in the amount of $100,000 shall
         thereupon become immediately due and payable without further notice or
         action required on the part of Medtech or the Placement Agent."

            4. Continuation of Effectiveness of Agreement. The parties hereby
confirm that the Agreement, as amended by the provisions of this Amendment,
continues to be in full force and effect.

         IN WITNESS WHEREOF, the parties have executed this Amendment to the
Agreement as of the date first above written.


                                         ABTECH INDUSTRIES, INC.

                                         By: /S/ Glenn R. Rink
                                            -------------------------------
                                            Glenn R. Rink, President

                                         MEDTECH DIAGNOSTICS, INC.

                                         By: /S/ Steven N. Bronson
                                            -------------------------------
                                            Steven N. Bronson, President

                                         CATALYST FINANCIAL CORP.

                                         By: /S/ Steven N. Bronson
                                            -------------------------------
                                            Steven N. Bronson, President