<PAGE>

                              AMENDMENT AND WAIVER
                                       TO
                                CREDIT AGREEMENT


        AMENDMENT AND WAIVER, dated as of June 29, 2004, (the "Amendment") to
the Credit Agreement, dated as of May 10, 2002 (as amended, the "Agreement"), by
and between ACETO CORPORATION, a New York corporation, ACETO AGRICULTURAL
CHEMICALS CORPORATION, a New York corporation, CDC PRODUCTS CORPORATION, a New
York corporation, MAGNUM RESEARCH CORP., a New York corporation, ACCI REALTY
CORP., a New York corporation, LARLABS CORP., a New York corporation, ARSYNCO
INC., a New Jersey corporation, ROEHR CHEMICALS, INC., a New York corporation,
ACETO INDUSTRIAL CHEMCIAL CORP., a New York corporation, jointly and severally
(each a "Company" and, collectively, the "Companies") and JPMORGAN CHASE BANK, a
New York banking corporation, (the "Lender").

                                    RECITALS

        The Company has requested certain amendments and waivers as set forth
herein and the Lender has agreed to such amendments and waivers subject to the
terms and conditions of this AMENDMENT.

           NOW, THEREFORE, the parties hereto hereby agree as follows:


                                   ARTICLE 1.
                         AMENDMENTS TO CREDIT AGREEMENT

        SECTION 1.1. The dollar amount "$15,000,000" in the definition of
Revolving Credit Commitment in Section 1.01 of the Agreement is hereby deleted
and the dollar amount "$10,000,000" is inserted in place thereof.

        SECTION 1.2. The definition of "Revolving Credit Commitment Termination
Date" in Section 1.01 of the Agreement is hereby amended to delete the date
"June 30, 2004" and to insert the date "June 30, 2007" in place thereof.

        SECTION 1.3. Section 3.04 is hereby amended to delete the text
"one-quarter of one-percent (.25%)" in clause (a) thereof and to insert the text
".15%".
<PAGE>

        SECTION 1.4. Section 7.03 of the Agreement is hereby amended to delete
the dollar amount "$1,000,000" in clause (e) thereof and to insert the dollar
amount "$3,000,000" in place thereof.

        SECTION 1.5. Section 7.06 of the Agreement is hereby amended to delete
the reference to the dollar amount "$5,000,000" in clause (d) thereof and to
insert the dollar amount "$10,000,000" in place thereof.

        SECTION 1.6. Section 7.06 of the Agreement is hereby further amended to
delete the dollar amount "$650,000" in clause (f) thereof and to insert the
dollar amount "$1,000,000" in place thereof.

        SECTION 1.7. Section 7.06 of the Agreement is hereby further amended to
delete the word "and" prior to clause (g) therein and to add the following text
at the end of clause (g):

                and (h) loans and investments by Aceto or its Subsidiaries to
                and in S.R.F.A., LLC., a New York limited liability company such
                loans and investments not to exceed $2,000,000 in the aggregate
                at any time outstanding.

        SECTION 1.8. Section 7.07 is hereby waived to permit the Borrowers to
engage in the bio-pharmaceutical industry as well as the business it currently
engages in.

        SECTION 1.9. Section 7.14 of the Agreement is hereby amended to delete
the dollar amount "$6,000,000" in clause (a)(ii) thereof and to insert the
dollar amount "$7,000,000" in place thereof.

        SECTION 1.10. Section 7.14 of the Agreement is hereby further amended to
delete the dollar amount "$2,500,000 in clause (a)(i) thereof and to insert the
dollar amount "$4,500,000" in place thereof.

        SECTION 1.11. Section 7.14 of the Agreement is hereby further amended to
delete the percentage "70%" in clause (c) thereof and to insert the percentage
"51%" in place thereof.

        SECTION 1.12. Section 7.15 of the Agreement is hereby amended to add the
following text after the word "Affiliate" each time is appears therein: "(other
than Aceto, any of Aceto's Subsidiaries or S.R.F.A., LLC)."

        SECTION 1.13. Section 7.13(b) of the Agreement is hereby amended to
delete the ratios "2.25:1.00" and "2.50:1.00" therein and to insert the ratio
"2.15:1.00" in place thereof in each instance.

                                       2
<PAGE>

        SECTION 1.14. Section 8.01(h) of the Agreement is hereby amended to
delete the dollar amount "$500,000" therein and to insert the dollar amount
"$1,000,000" in place thereof.

        SECTION 1.15. Section 8.01(e) of the Agreement is hereby amended to
delete the dollar amount "$500,000" therein and to insert the dollar amount
"$1,000,000" in place thereof.

        SECTION 1.16. Section 7.13(a) of the Agreement is hereby amended to
delete the dollar amount "$55,000,000" and to insert the dollar amount
"$72,000,000" in place thereof.

        SECTION 1.17. Schedules I, III, IV and VIII are hereby amended and
restated in their entirety as set forth as Schedules I, III, IV and VIII to this
Amendment.

                                   ARTICLE 2.
                           WAIVERS TO CREDIT AGREEMENT

        SECTION 2.1. Compliance with Section 7.14 of the Agreement is hereby
waived with respect to the payment by Aceto of dividends in the fiscal year
ending June 30, 2004 provided that the aggregate dividends paid by Aceto during
such period did not exceed $2,526,000.

        SECTION 2.2. Compliance with Section 6.13 of the Agreement is hereby
waived with respect to the failure to execute a Pledge Agreement and to provide
the other documentation required thereunder with respect to Aceto Pharmaceutical
Shanghai, Ltd. and Aceto (Shanghai), Ltd. provided that Companies are in
compliance with their obligations thereunder with respect to such entities on or
prior to August 15, 2004.

                                   ARTICLE 3.
                         REPRESENTATIONS AND WARRANTIES

        The Companies hereby represent and warrant to the Lender that:

        SECTION 3.1. Each of the representations and warranties set forth in
each Loan Document is true and correct is all material respects as of the date
hereof with respect to the Companies, with the same effect as though made on the
date hereof (unless any such representation and warranty is as of a specific
date, in which event, as of such date), and is hereby incorporated herein in
full by reference as if fully restated herein in its entirety.

        SECTION 3.2. To induce the Lender to enter into this Amendment and to
continue to make advances to the Companies pursuant to the Agreement, as amended
hereby, the Companies hereby acknowledge and agree that, as of the date hereof,
and after giving effect to

                                       3
<PAGE>

the terms hereof, and all prior waivers and amendments executed by the Lender
and the Companies prior to the date hereof , there exists no Default or Event of
Default.

        SECTION 3.3. The Companies have the corporate power and authority to
enter into, perform and deliver this Amendment and any other documents,
instruments, agreements or other writings to be delivered in connection
herewith. This Amendment and all documents contemplated hereby or delivered in
connection herewith, have each been duly authorized, executed and delivered and
the transactions contemplated herein have been duly authorized.

        SECTION 3.4. This Amendment and any other documents, agreements or
instruments now or hereafter executed and delivered to the Lender by the
Companies in connection herewith constitute (or shall, when delivered,
constitute) valid and legally binding obligations of Companies, each of which is
and shall be enforceable against Companies in accordance with their respective
terms.

        SECTION 3.5. No consent, waiver or approval of any entity is or will be
required in connection with the execution, delivery, performance, validity or
enforcement of this Amendment, or any other agreements, instruments or documents
to be executed and/or delivered in connection herewith or pursuant hereto.

        SECTION 3.6. Each of the Loan Documents to which it is a party and each
lien and security interest granted thereunder is in full force and effect and
will remain in full force and effect after giving effect to this Amendment.

        SECTION 3.7. Except with respect to the certificate of incorporation of
Aceto, a true, correct and complete copy of which has been provided to the
Lender, neither the certificate of incorporation nor the bylaws or other
organizational documents of any Company has been amended since May 10, 2002.

                                   ARTICLE 4.
                           CONDITIONS TO EFFECTIVENESS

        SECTION 4.1. The Amendments and Waivers provided herein shall not be
effective unless the Lender shall have received on or prior to the date hereof
the following:

                (a)     a Note Modification Agreement dated the date hereof in
                        the form attached hereto as Annex I duly executed by the
                        Company.

                (b)     payment of a nonrefundable amendment and waiver fee in
                        the amount of $25,000.

                                       4
<PAGE>

                                   ARTICLE 5.
                                 MISCELLANEOUS

        SECTION 5.1. This Amendment may be executed in any number of
counterparts, all of which taken together shall constitute one and the same
instrument, and any party hereto may execute this Amendment by signing any such
counterpart.

        SECTION 5.2. THIS AMENDMENT SHALL BE GOVERNED BY, AND INTERPRETED AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK (WITHOUT GIVING
EFFECT TO THE CONFLICT OF LAWS PROVISIONS THEREOF).

        SECTION 5.3. On and after the effective date of this Amendment, each
reference in the Agreement to "this Agreement", "hereunder", "hereof" or words
of like import referring to the Agreement, and each reference in the Loan
Documents to "the Agreement", "thereunder", "thereof", or words of like import
referring to the Agreement, shall mean and be a reference to the Agreement as
amended by this Amendment. The Agreement, as amended by this Amendment, is and
shall continue to be in full force and effect and is hereby in all respects
ratified and confirmed. This Amendment shall constitute a "Loan Document".

        SECTION 5.4. The Companies agree to take such further actions as the
Lender shall reasonably request in connection herewith to evidence the
amendments herein contained to the Agreement.





                                       5
<PAGE>

        IN WITNESS WHEREOF, the Companies and the Lender have caused this
Amendment to be duly executed as of the day and year first above written.


                                       ACETO CORPORATION


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: CEO

                                       ACETO AGRICULTURAL CHEMICALS CORPORATION


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: Director

                                       CDC PRODUCTS CORPORATION


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: Director

                                       MAGNUM RESEARCH CORP.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       ACCI REALTY CORP.

                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President


                                       6
<PAGE>

                                       LARLABS CORP.

                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       ARSYNCO INC.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: Chairman

                                       ROEHR CHEMICALS, INC.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       ACETO INDUSTRIAL CHEMCIAL CORP.

                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       JPMORGAN CHASE BANK


                                       By:  /s/ Sanford Wald
                                           -----------------------------------
                                       Name:  Sanford Wald
                                       Title: Vice President


                                       7
<PAGE>

                                                                         ANNEX I

                        FIRST NOTE MODIFICATION AGREEMENT

        THIS AGREEMENT, made as of June 29, 2004 by and between ACETO
CORPORATION, a New York corporation, ACETO AGRICULTURAL CHEMICALS CORPORATION, a
New York corporation, CDC PRODUCTS CORPORATION, a New York corporation, MAGNUM
RESEARCH CORP., a New York corporation, ACCI REALTY CORP., a New York
corporation, LARLABS CORP., a New York corporation, ARSYNCO INC., a New Jersey
corporation, ROEHR CHEMICALS, INC., a New York corporation, ACETO INDUSTRIAL
CHEMCIAL CORP., a New York corporation (each a "Company" and, collectively, the
"Companies"), and JPMORGAN CHASE BANK, a New York banking corporation (the
"Lender").

                                    RECITALS

        A.      Pursuant to a Credit Agreement dated as of May 10, 2002 by and
among the Companies and the Lender (as amended, the "Credit Agreement"), the
Company executed and delivered to the Lender a Revolving Credit Note dated May
10, 2002 (the "Note").

        B.      The Company and the Lender desire to amend the Note as set forth
herein.

        NOW THEREFORE, the Company and the Lender agree as follows:

        1.      The text "FIFTEEN MILLION DOLLARS ($15,000,000)" is hereby
deleted and the text "TEN MILLION DOLLARS ($10,000,000)" is inserted in place
thereof.

        2.      The dollar amount "$15,000,000" in the upper left hand corner of
the Note is hereby deleted and the dollar amount "$10,000,000" is inserted in
place thereof.

        3.      Except as expressly amended hereby, the Note shall remain in
full force and effect in accordance with the terms thereof. The amendment herein
contained is limited specifically to the matter set forth above and does not
constitute directly or by implication an amendment or waiver of any other
provision of the Note.

        4.      This Agreement may be executed in two or more counterparts each
of which shall be deemed an original and all of which taken together shall
constitute one and the same agreement.

        5.      Capitalized terms used herein and not defined shall have the
meanings set forth in the Credit Agreement prior to giving effect to the
Amendment thereto dated the date hereof.

                                       8
<PAGE>

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

                                       JPMORGAN CHASE BANK


                                       By:  /s/ Sanford Wald
                                           -----------------------------------
                                       Name:  Sanford Wald
                                       Title: Vice President

                                       ACETO CORPORATION


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: CEO

                                       ACETO AGRICULTURAL CHEMICALS CORPORATION


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: Director

                                       CDC PRODUCTS CORPORATION


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: Director

                                       MAGNUM RESEARCH CORP.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       9
<PAGE>

                                       ACCI REALTY CORP.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       LARLABS CORP.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       ARSYNCO INC.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: Chairman

                                       ROEHR CHEMICALS, INC.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       ACETO INDUSTRIAL CHEMCIAL CORP.


                                       By:  /s/ Leonard  Schwartz
                                           -----------------------------------
                                       Name:  Leonard Schwartz
                                       Title: President

                                       10