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                                                                     EXHIBIT 4.3

                                SIPEX CORPORATION

                       2002 NONSTATUTORY STOCK OPTION PLAN

1.       Purposes of the Plan. The purposes of this Nonstatutory Stock Option
         Plan are:

         -        to attract and retain the best available personnel for
                  positions of substantial responsibility,

         -        to provide additional incentive to Employees, Directors and
                  Consultants, and

         -        to promote the success of the Company's business.

         Options granted under the Plan will be Nonstatutory Stock Options.

2.       Definitions. As used herein, the following definitions shall apply:

         (a)      "Administrator" means the Board or any of its Committees as
                  shall be administering the Plan, in accordance with Section 4
                  of the Plan.

         (b)      "Applicable Laws" means the requirements relating to the
                  administration of stock option plans under U.S. state
                  corporate laws, U.S. federal and state securities laws, the
                  Code, any stock exchange or quotation system on which the
                  Common Stock is listed or quoted and the applicable laws of
                  any foreign country or jurisdiction where Options are, or will
                  be, granted under the Plan.

         (c)      "Board" means the Board of Directors of the Company.

         (d)      "Code" means the Internal Revenue Code of 1986, as amended.

         (e)      "Committee" means a committee of Directors appointed by the
                  Board in accordance with Section 4 of the Plan.

         (f)      "Common Stock" means the Common Stock of the Company.

         (g)      "Company" means Sipex Corporation, a Massachusetts
                  corporation.

         (h)      "Consultant" means any person, including an advisor, engaged
                  by the Company or a Parent or Subsidiary to render services to
                  such entity.

         (i)      "Director" means a member of the Board.

         (j)      "Disability" means total and permanent disability as defined
                  in Section 22(e)(3) of the Code.

         (k)      "Employee" means any person, including Officers, employed by
                  the Company or any Parent or Subsidiary of the Company. A
                  Service Provider shall not cease to be an


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                  Employee in the case of (i) any leave of absence approved by
                  the Company or (ii) transfers between locations of the Company
                  or between the Company, its Parent, any Subsidiary, or any
                  successor. Neither service as a Director nor payment of a
                  director's fee by the Company shall be sufficient to
                  constitute "employment" by the Company.

         (l)      "Exchange Act" means the Securities Exchange Act of 1934, as
                  amended.


         (m)      "Fair Market Value" means, as of any date, the value of Common
                  Stock determined as follows:


                  (i)      If the Common Stock is listed on any established
                           stock exchange or a national market system, including
                           without limitation the Nasdaq National Market or The
                           Nasdaq SmallCap Market of The Nasdaq Stock Market,
                           its Fair Market Value shall be the closing sales
                           price for such stock (or the closing bid, if no sales
                           were reported) as quoted on such exchange or system
                           on the date of grant, or if unavailable, for the last
                           market trading day prior to date of grant, as
                           reported in The Wall Street Journal or such other
                           source as the Administrator deems reliable;

                  (ii)     If the Common Stock is regularly quoted by a
                           recognized securities dealer but selling prices are
                           not reported, the Fair Market Value of a Share of
                           Common Stock shall be the mean between the high bid
                           and low asked prices for the Common Stock on the date
                           of grant, or if unavailable, on the last market
                           trading day prior to the date of grant, as reported
                           in The Wall Street Journal or such other source as
                           the Administrator deems reliable;

                  (iii)    In the absence of an established market for the
                           Common Stock, the Fair Market Value shall be
                           determined in good faith by the Administrator.

         (n)      "Notice of Grant" means a written or electronic notice
                  evidencing certain terms and conditions of an individual
                  Option grant. The Notice of Grant is part of the Option
                  Agreement.

         (o)      "Officer" means any Employee who holds office at the level of
                  Vice President or above.

         (p)      "Option" means a nonstatutory stock option granted pursuant to
                  the Plan, that is not intended to qualify as an incentive
                  stock option within the meaning of Section 422 of the Code and
                  the regulations promulgated thereunder.

         (q)      "Option Agreement" means an agreement between the Company and
                  an Optionee evidencing the terms and conditions of an
                  individual Option grant. The Option Agreement is subject to
                  the terms and conditions of the Plan.

         (r)      "Option Exchange Program" means a program whereby outstanding
                  options are surrendered in exchange for options with a lower
                  exercise price.

         (s)      "Optioned Stock" means the Common Stock subject to an Option.


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         (t)      "Optionee" means the holder of an outstanding Option granted
                  under the Plan.

         (u)      "Parent" means a "parent corporation," whether now or
                  hereafter existing, as defined in Section 424(e) of the Code.

         (v)      "Plan" means this 2002 Nonstatutory Stock Option Plan.

         (w)      "Service Provider" means an Employee including an Officer,
                  Consultant or Director.

         (x)      "Share" means a share of the Common Stock, as adjusted in
                  accordance with Section 12 of the Plan.

         (y)      "Subsidiary" means a "subsidiary corporation," whether now or
                  hereafter existing, as defined in Section 424(f) of the Code.

3.       Stock Subject to the Plan. Subject to the provisions of Section 12 of
         the Plan, the maximum aggregate number of Shares which may be optioned
         and sold under the Plan is One Million (1,000,000) Shares. The Shares
         may be authorized, but unissued, or reacquired Common Stock.

         If an Option expires or becomes unexercisable without having been
         exercised in full, or is surrendered pursuant to an Option Exchange
         Program, the unpurchased Shares which were subject thereto shall become
         available for future grant or sale under the Plan (unless the Plan has
         terminated).

4.       Administration of the Plan.

         (a)      Administration. The Plan shall be administered by (i) the
                  Board or (ii) a Committee, which committee shall be
                  constituted to satisfy Applicable Laws.

         (b)      Powers of the Administrator. Subject to the provisions of the
                  Plan, and in the case of a Committee, subject to the specific
                  duties delegated by the Board to such Committee, the
                  Administrator shall have the authority, in its discretion:

                  (i)      to determine the Fair Market Value of the Common
                           Stock;

                  (ii)     to select the Service Providers to whom Options may
                           be granted hereunder;

                  (iii)    to determine whether and to what extent Options are
                           granted hereunder;

                  (iv)     to determine the number of shares of Common Stock to
                           be covered by each Option granted hereunder;

                  (v)      to approve forms of agreement for use under the Plan;

                  (vi)     to determine the terms and conditions, not
                           inconsistent with the terms of the Plan, of any award
                           granted hereunder. Such terms and conditions include,
                           but are not limited to, the exercise price, the time
                           or times when Options may be exercised (which may be
                           based on performance criteria), any vesting
                           acceleration or waiver of forfeiture restrictions,
                           and any restriction or


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                           limitation regarding any Option or the shares of
                           Common Stock relating thereto, based in each case on
                           such factors as the Administrator, in its sole
                           discretion, shall determine;


                  (vii)    to reduce the exercise price of any Option to the
                           then current Fair Market Value if the Fair Market
                           Value of the Common Stock covered by such Option
                           shall have declined since the date the Option was
                           granted;

                  (viii)   to institute an Option Exchange Program;

                  (ix)     to construe and interpret the terms of the Plan and
                           awards granted pursuant to the Plan;

                  (x)      to prescribe, amend and rescind rules and regulations
                           relating to the Plan, including rules and regulations
                           relating to sub-plans established for the purpose of
                           qualifying for preferred tax treatment under foreign
                           tax laws;

                  (xi)     to modify or amend each Option (subject to Section
                           14(b) of the Plan), including the discretionary
                           authority to extend the post-termination
                           exercisability period of Options longer than is
                           otherwise provided for in the Plan;

                  (xii)    to authorize any person to execute on behalf of the
                           Company any instrument required to effect the grant
                           of an Option previously granted by the Administrator;

                  (xiii)   to determine the terms and restrictions applicable to
                           Options;

                  (xiv)    to allow Optionees to satisfy withholding tax
                           obligations by electing to have the Company withhold
                           from the Shares to be issued upon exercise of an
                           Option that number of Shares having a Fair Market
                           Value equal to the amount required to be withheld.
                           The Fair Market Value of the Shares to be withheld
                           shall be determined on the date that the amount of
                           tax to be withheld is to be determined. All elections
                           by an Optionee to have Shares withheld for this
                           purpose shall be made in such form and under such
                           conditions as the Administrator may deem necessary or
                           advisable; and

                  (xv)     to make all other determinations deemed necessary or
                           advisable for administering the Plan.

         (c)      Effect of Administrator's Decision. The Administrator's
                  decisions, determinations and interpretations shall be final
                  and binding on all Optionees and any other holders of Options.

5.       Eligibility. Options may be granted to Service Providers.

6.       Limitation. Neither the Plan nor any Option shall confer upon an
         Optionee any right with respect to continuing the Optionee's
         relationship as a Service Provider with the Company, nor shall they
         interfere in any way with the Optionee's right or the Company's right
         to terminate such relationship at any time, with or without cause.


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7.       Term of Plan. The Plan shall become effective upon its adoption by the
         Board. It shall continue in effect for ten (10) years, unless sooner
         terminated under Section 14 of the Plan.

8.       Term of Option. The term of each Option shall be stated in the Option
         Agreement.

9.       Option Exercise Price and Consideration.

         (a)      Exercise Price. The per share exercise price for the Shares to
                  be issued pursuant to exercise of an Option shall be
                  determined by the Administrator.

         (b)      Waiting Period and Exercise Dates. At the time an Option is
                  granted, the Administrator shall fix the period within which
                  the Option may be exercised and shall determine any conditions
                  which must be satisfied before the Option may be exercised.

         (c)      Form of Consideration. The Administrator shall determine the
                  acceptable form of consideration for exercising an Option,
                  including the method of payment. Such consideration may
                  consist entirely of:

                  (i)      cash;

                  (ii)     check;

                  (iii)    promissory note;

                  (iv)     other Shares which (A) in the case of Shares acquired
                           upon exercise of an option, have been owned by the
                           Optionee for more than six months on the date of
                           surrender, and (B) have a Fair Market Value on the
                           date of surrender equal to the aggregate exercise
                           price of the Shares as to which said Option shall be
                           exercised;

                  (v)      consideration received by the Company under a
                           cashless exercise program implemented by the Company
                           in connection with the Plan;

                  (vi)     a reduction in the amount of any Company liability to
                           the Optionee, including any liability attributable to
                           the Optionee's participation in any Company-sponsored
                           deferred compensation program or arrangement; (vii)
                           such other consideration and method of payment for
                           the issuance of Shares to the extent permitted by
                           Applicable Laws; or

                  (viii)   any combination of the foregoing methods of payment.

10.      Exercise of Option.

         (a)      Procedure for Exercise; Rights as a Shareholder. Any Option
                  granted hereunder shall be exercisable according to the terms
                  of the Plan and at such times and under such conditions as
                  determined by the Administrator and set forth in the Option
                  Agreement. An Option may not be exercised for a fraction of a
                  Share.


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                  An Option shall be deemed exercised when the Company receives:
                  (i) written or electronic notice of exercise (in accordance
                  with the Option Agreement) from the person entitled to
                  exercise the Option, and (ii) full payment for the Shares with
                  respect to which the Option is exercised. Full payment may
                  consist of any consideration and method of payment authorized
                  by the Administrator and permitted by the Option Agreement and
                  the Plan. Shares issued upon exercise of an Option shall be
                  issued in the name of the Optionee or, if requested by the
                  Optionee, in the name of the Optionee and his or her spouse.
                  Until the Shares are issued (as evidenced by the appropriate
                  entry on the books of the Company or of a duly authorized
                  transfer agent of the Company), no right to vote or receive
                  dividends or any other rights as a shareholder shall exist
                  with respect to the Optioned Stock, notwithstanding the
                  exercise of the Option. The Company shall issue (or cause to
                  be issued) such Shares promptly after the Option is exercised.
                  No adjustment will be made for a dividend or other right for
                  which the record date is prior to the date the Shares are
                  issued, except as provided in Section 12 of the Plan.

                  Exercising an Option in any manner shall decrease the number
                  of Shares thereafter available, both for purposes of the Plan
                  and for sale under the Option, by the number of Shares as to
                  which the Option is exercised.

         (b)      Termination of Relationship as a Service Provider. If an
                  Optionee ceases to be a Service Provider, other than upon the
                  Optionee's death or Disability, the Optionee may exercise his
                  or her Option, but only within such period of time as is
                  specified in the Option Agreement, and only to the extent that
                  the Option is vested on the date of termination (but in no
                  event later than the expiration of the term of such Option as
                  set forth in the Option Agreement). In the absence of a
                  specified time in the Option Agreement, the Option shall
                  remain exercisable for three (3) months following the
                  Optionee's termination. If, on the date of termination, the
                  Optionee is not vested as to his or her entire Option, the
                  Shares covered by the unvested portion of the Option shall
                  revert to the Plan. If, after termination, the Optionee does
                  not exercise his or her Option within the time specified by
                  the Administrator, the Option shall terminate, and the Shares
                  covered by such Option shall revert to the Plan.

         (c)      Disability of Optionee. If an Optionee ceases to be a Service
                  Provider as a result of the Optionee's Disability, the
                  Optionee may exercise his or her Option within such period of
                  time as is specified in the Option Agreement, to the extent
                  the Option is vested on the date of termination (but in no
                  event later than the expiration of the term of such Option as
                  set forth in the Option Agreement). In the absence of a
                  specified time in the Option Agreement, the Option shall
                  remain exercisable for six (6) months following the Optionee's
                  termination. If, on the date of termination, the Optionee is
                  not vested as to his or her entire Option, the Shares covered
                  by the unvested portion of the Option shall revert to the
                  Plan. If, after termination, the Optionee does not exercise
                  his or her Option within the time specified herein, the Option
                  shall terminate, and the Shares covered by such Option shall
                  revert to the Plan.

         (d)      Death of Optionee. If an Optionee dies while a Service
                  Provider, the Option may be exercised within such period of
                  time as is specified in the Option Agreement (but in no event
                  later than the expiration of the term of such Option as set
                  forth in the Notice of Grant), by the Optionee's estate or by
                  a person who acquires the right to exercise the Option by
                  bequest or inheritance, but only to the extent that the Option
                  is vested


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                  on the date of death. In the absence of a specified time in
                  the Option Agreement, the Option shall remain exercisable for
                  six (6) months following the Optionee's termination. If, at
                  the time of death, the Optionee is not vested as to his or her
                  entire Option, the Shares covered by the unvested portion of
                  the Option shall immediately revert to the Plan. The Option
                  may be exercised by the executor or administrator of the
                  Optionee's estate or, if none, by the person(s) entitled to
                  exercise the Option under the Optionee's will or the laws of
                  descent or distribution. If the Option is not so exercised
                  within the time specified herein, the Option shall terminate,
                  and the Shares covered by such Option shall revert to the
                  Plan.

         (e)      Buyout Provisions. The Administrator may at any time offer to
                  buy out for a payment in cash or Shares, an Option previously
                  granted based on such terms and conditions as the
                  Administrator shall establish and communicate to the Optionee
                  at the time that such offer is made.

11.      Non-Transferability of Options. Unless determined otherwise by the
         Administrator, an Option may not be sold, pledged, assigned,
         hypothecated, transferred, or disposed of in any manner other than by
         will or by the laws of descent or distribution and may be exercised,
         during the lifetime of the Optionee, only by the Optionee. If the
         Administrator makes an Option transferable, such Option shall contain
         such additional terms and conditions as the Administrator deems
         appropriate.

12.      Adjustments Upon Changes in Capitalization, Dissolution, Merger or
         Asset Sale.

         (a)      Changes in Capitalization. Subject to any required action by
                  the shareholders of the Company, the number of shares of
                  Common Stock covered by each outstanding Option, and the
                  number of shares of Common Stock which have been authorized
                  for issuance under the Plan but as to which no Options have
                  yet been granted or which have been returned to the Plan upon
                  cancellation or expiration of an Option, as well as the price
                  per share of Common Stock covered by each such outstanding
                  Option, shall be proportionately adjusted for any increase or
                  decrease in the number of issued shares of Common Stock
                  resulting from a stock split, reverse stock split, stock
                  dividend, combination or reclassification of the Common Stock,
                  or any other increase or decrease in the number of issued
                  shares of Common Stock effected without receipt of
                  consideration by the Company; provided, however, that
                  conversion of any convertible securities of the Company shall
                  not be deemed to have been "effected without receipt of
                  consideration." Such adjustment shall be made by the Board,
                  whose determination in that respect shall be final, binding
                  and conclusive. Except as expressly provided herein, no
                  issuance by the Company of shares of stock of any class, or
                  securities convertible into shares of stock of any class,
                  shall affect, and no adjustment by reason thereof shall be
                  made with respect to, the number or price of shares of Common
                  Stock subject to an Option.

         (b)      Dissolution or Liquidation. In the event of the proposed
                  dissolution or liquidation of the Company, the Administrator
                  shall notify each Optionee as soon as practicable prior to the
                  effective date of such proposed transaction. The Administrator
                  in its discretion may provide for an Optionee to have the
                  right to exercise his or her Option within a specified number
                  of days of the date of such notice as to all of the Optioned
                  Stock covered thereby, including, in the discretion of the
                  Administrator, Shares as to which the Option would not
                  otherwise be exercisable. To the extent it has not been


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                  previously exercised, an Option will terminate immediately
                  prior to the consummation of such proposed action.

         (c)      Merger or Asset Sale. In the event of a merger of the Company
                  with or into another corporation or other reorganization in
                  which the holders of the outstanding voting stock of the
                  Company immediately preceding the consummation of such event,
                  shall, immediately following such event, hold, as a group,
                  less than a majority of the voting securities of the surviving
                  or successor entity, or the sale of substantially all of the
                  assets of the Company (each, an "Acquisition"), the committee
                  or the board of directors of any entity assuming the
                  obligations of the Company hereunder (the "Successor Board"),
                  shall, with respect to each outstanding Option, either (i)
                  make appropriate provision for the continuation of such
                  Options by substituting on an equitable basis for the Shares
                  then subject to such Options either (a) the consideration
                  payable with respect to the outstanding Shares in connection
                  with the Acquisition; (b) shares of stock of the surviving or
                  successor corporation or (c) such other securities as the
                  Successor Board deems appropriate, the fair market value of
                  which shall not materially exceed the fair market value of the
                  Shares subject to such Options immediately preceding the
                  Acquisition; or (ii) upon written notice to the Optionees,
                  provide that all Options must be exercised, to the extent then
                  exercisable or to be exercisable as a result of the
                  Acquisition, within a specified number of days of the date of
                  such notice, and the Option shall terminate upon the
                  expiration of such period; or (iii) terminate all Options in
                  exchange for a cash payment equal to the excess of the fair
                  market value of the Shares subject to such Options (to the
                  extent then exercisable or to be exercisable as a result of
                  the Acquisition) over the exercise price thereof.

         (d)      Recapitalization or Reorganization. In the event of a
                  recapitalization or reorganization of the Company (other than
                  a transaction described in Section 12(c), above) pursuant to
                  which securities of the Company or of another corporation are
                  issued with respect to the outstanding Shares, an Optionee
                  upon exercising an Option shall be entitled to receive, in
                  exchange for the exercise price paid, the securities Optionee
                  would have received if Optionee had exercised such Option
                  prior to such recapitalization or reorganization.

13.      Date of Grant. The date of grant of an Option shall be, for all
         purposes, the date on which the Administrator makes the determination
         granting such Option, or such other later date as is determined by the
         Administrator. Notice of the determination shall be provided to each
         Optionee within a reasonable time after the date of such grant.

14.      Amendment and Termination of the Plan.

         (a)      Amendment and Termination. The Board may at any time amend,
                  alter, suspend or terminate the Plan.

         (b)      Effect of Amendment or Termination. No amendment, alteration,
                  suspension or termination of the Plan shall impair the rights
                  of any Optionee, unless mutually agreed otherwise between the
                  Optionee and the Administrator, which agreement must be in
                  writing and signed by the Optionee and the Company.
                  Termination of the Plan shall not affect the Administrator's
                  ability to exercise the powers granted to it


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                  hereunder with respect to options granted under the Plan prior
                  to the date of such termination.

15.      Conditions Upon Issuance of Shares.

         (a)      Legal Compliance. Shares shall not be issued pursuant to the
                  exercise of an Option unless the exercise of such Option and
                  the issuance and delivery of such Shares shall comply with
                  Applicable Laws and shall be further subject to the approval
                  of counsel for the Company with respect to such compliance.

         (b)      Investment Representations. As a condition to the exercise of
                  an Option the Company may require the person exercising such
                  Option to represent and warrant at the time of any such
                  exercise that the Shares are being purchased only for
                  investment and without any present intention to sell or
                  distribute such Shares if, in the opinion of counsel for the
                  Company, such a representation is required.

16.      Inability to Obtain Authority. The inability of the Company to obtain
         authority from any regulatory body having jurisdiction, which authority
         is deemed by the Company's counsel to be necessary to the lawful
         issuance and sale of any Shares hereunder, shall relieve the Company of
         any liability in respect of the failure to issue or sell such Shares as
         to which such requisite authority shall not have been obtained.

17.      Reservation of Shares. The Company, during the term of this Plan, will
         at all times reserve and keep available such number of Shares as shall
         be sufficient to satisfy the requirements of the Plan.


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