EXHIBIT 10.13


                  AMENDMENT TO TOLL PROCESSING AGREEMENT AND TO
                      AGREEMENT MODIFYING AND EXTENDING THE
               TOLL PROCESSING AGREEMENT BETWEEN MSI AND SHAMROCK

                  This  is an  amendment  made on  March  17,  1997 to the  Toll
Processing  Agreement dated November 1, 1994 (the "Toll  Processing  Agreement")
between Medical  Sterilization,  Inc.  ("MSI") and Shamrock  Technologies,  Inc.
("Shamrock")  and to  the  Agreement  dated  November  1,  1995,  modifying  and
extending the terms of the Toll  Processing  Agreement  (the  "Modification  and
Extension  Agreement").  The  Toll  Processing  Agreement  as  modified  by  the
Modification  and  Extension  Agreement  shall  remain in full  force and effect
except as further modified hereby.

         1. Pursuant to Paragraph 2 of the Modification and Extension Agreement,
Shamrock  hereby elects to extend the term of the Toll  Processing Agreement for
three months to September 30, 1997.

         2.  Shamrock  may  elect to  extend  the  term of the  Toll  Processing
Agreement for one month increments through December 31, 1997,  provided Shamrock
notifies  MSI in writting of such intent not less than three months prior to the
beginning of the month to which the extension applies.

         3.  Section  4.1(a) of the  Modification  and  Extension  Agreement  is
amended effective January 1, 1996 as follows:

          Item                             Price
     a) Blender Irradiation     $3.75 per Kilowatt hour

         4.  Effective  January 1, 1996,  Section  5.1 of the  Modification  and
Extension Agreement are hereby eliminated.

         5.  Effective  November  1,  1994,  Section  4 of the  Toll  Processing
Agreement is deleted.

         6. Effective January 1, 1997 Section 8 of the Toll Processing Agreement
is amended to read as follows:

            8. Invoicing and Payment: (a) With respect to Blender Irradiation of
         PTFE, MSI shall invoice Shamrock not more than twice per month. Payment
         of such invoices  shall be due 60 days from the date of the invoice and
         Shamrock  shall be entitled  to a discount  of 3% for any payment  made
         within 10 days of receipt of the invoice by Shamrock.

     (b) With respect to all services  other than Blender  Irradiation  of PTFE,
     MSI shall invoice Shamrock at the time the materials  processed are shipped
     from MSI's premises. Payment of such invoices shall be due 30 days from the
     date of the invoice.  Notwithstanding the foregoing,  any amounts remaining
     unbilled at the date of termination of the Toll Processing



Agreement  shall be billed as of such date and shall be due 30 days  thereafter,
without discount for early payment.


         Agreed:                                     Agreed:

         Medical Sterilization, Inc.                 Shamrock Technologies, Inc.

         /s/ D. Michael Deignan                      /s/ William B. Neuberg
         ---------------------------                 ---------------------------
         D. Michael Deignan                           William B. Neuberg





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