Exhibit 4.5

THE SECURITIES EVIDENCED HEREBY AND THE SECURITIES ISSUABLE UPON EXERCISE HEREOF
HAVE NOT BEEN REGISTERED  UNDER THE SECURITIES ACT OF 1933, AS AMENDED  ("ACT"),
OR UNDER THE SECURITIES LAWS OF ANY STATE, AND MAY NOT BE OFFERED OR SOLD EXCEPT
PURSUANT TO (I) AN EFFECTIVE  REGISTRATION  STATEMENT UNDER THE ACT, (II) TO THE
EXTENT  APPLICABLE,  RULE 144 UNDER THE ACT (OR ANY SIMILAR  RULE UNDER SUCH ACT
RELATING TO THE DISPOSITION OF SECURITIES),  OR (III) AN OPINION OF COUNSEL,  IF
SUCH OPINION SHALL BE REASONABLY  SATISFACTORY TO COUNSEL TO THE ISSUER, THAT AN
EXEMPTION FROM REGISTRATION UNDER SUCH ACT IS AVAILABLE.

         VOID AFTER 5:00 P.M., NEW YORK CITY TIME, ON SEPTEMBER 14, 2003

                                  HEMASURE INC.
                    COMMON STOCK PURCHASE WARRANT CERTIFICATE

                                                              1,000,000 WARRANTS

         THIS WARRANT  CERTIFIES  that  SEPRACOR  INC.,  a Delaware  corporation
("Holder"),  or  registered  assigns,  is the owner of  1,000,000  Common  Stock
Purchase Warrants (the "Warrants"), each of which entitles the registered holder
thereof (the "Warrant Holder") to purchase one (1) fully paid and non-assessable
share of common stock,  par value $.01 per share ("Common  Stock"),  of HemaSure
Inc., a Delaware  corporation (the  "Company"),  at any time after September 14,
1999 and before 5:00 P.M.,  New York City time on September 14, 2003, at a price
of $0.69 per share of  Common  Stock  (subject  to the  adjustments  hereinafter
referred  to),  by  surrendering  this  Warrant  Certificate,  with  the form of
election to purchase  attached hereto duly executed,  at the corporate office of
the  Company,  and by paying in full for each share of Common  Stock as to which
Warrants represented hereby are exercised,  and upon compliance with and subject
to the conditions set forth in the Warrant Agreement,  dated as of September 15,
1998, between the Company and Holder (the "Warrant Agreement").

         Upon any exercise of Warrants evidenced hereby, the form of election to
purchase attached hereto must be properly  completed and executed.  In the event
that upon any  exercise  of  Warrants  evidenced  hereby the number of  Warrants
exercised  shall be less than the total  number of  Warrants  evidenced  hereby,
there  shall be issued to the holder  hereof a new Warrant  Certificate,  in all
respects similar to this Warrant Certificate,  evidencing the number of Warrants
not exercised.  The purchase  price per share of Common Stock,  as adjusted from
time to time,  is herein  called  the  "Warrant  Price"  and the  Warrant  Price
multiplied by the number of shares of Common Stock purchased  simultaneously  is
herein called the "Purchase  Price." The Purchase Price payable upon exercise of
Warrants  shall be paid, at the option of the Holder  specified in its notice of
exercise, (1) by wire transfer or by certified or official bank check payable to
the order of the Company in immediately  available  funds in lawful money of the
United  States of America;  or (ii) by  reducing  the number of shares of Common
Stock  issuable to the Holder by a number of shares of Common  Stock that have a
value equal to the Exercise Price which  otherwise would have been paid. For the
purpose of any exercise pursuant to the previous sentence,  the value of a share
of Common Stock shall be the last reported sale price of the Common Stock on the
OTC  Bulletin  Board,  or any other  interdealer  quotation  system on which the
Common Stock is included for  quotation,  or, if none,  the fair market value of
such shares as reasonably determined by the Board of Directors of the Company.


728538.3

<PAGE>



         No fraction of a share of Common Stock will be issued upon the exercise
of any  Warrant.  In any  transaction  in  which  Warrants  are  exercised,  the
registered  holder  shall be  entitled  to  purchase  as many full shares as are
included  in the  product  of the  number of  Warrants  being  exercised  in the
transaction  times  the  number  of  shares  (including  fractions  of a  share)
purchasable upon exercise of one Warrant.

         This Warrant  Certificate  is issued  under and the Warrants  evidenced
hereby  are  subject  to,  the terms and  provisions  contained  in the  Warrant
Agreement,  to all the terms and  provisions of which the holder of this Warrant
Certificate,  by  acceptance  hereof,  assents.  Reference is hereby made to the
Warrant Agreement for a more complete statement of the rights and limitations of
rights of the  registered  holder hereof and the rights and  obligations  of the
Company thereunder. Copies of the Warrant Agreement are on file at the office of
the Company.

         This  Warrant   Certificate  and  similar  Warrant   Certificates  when
surrendered  at the  corporate  office of the Company by the  registered  holder
hereof in person or by attorney duly authorized in writing may be exchanged,  in
the manner and subject to the limitations provided in the Warrant Agreement, but
without  payment of any service  charge,  for  another  Warrant  Certificate  or
Warrant Certificates of like tenor and evidencing in the aggregate the number of
Warrants evidenced by the Warrant Certificates so surrendered.

         Upon due  presentation  for  registration  of transfer of this  Warrant
Certificate at the corporate office of the Company, a new Warrant Certificate or
Warrant Certificates of like tenor and evidencing in the aggregate the number of
Warrants  evidenced by this Warrant  Certificate shall be issued to a transferee
in exchange for this Warrant Certificate, subject to the limitations provided in
the Warrant  Agreement,  without charge except for any tax or other governmental
charge imposed in connection therewith.

         Prior to due presentment  for  registration of transfer of this Warrant
Certificate,  the Company may deem and treat the registered holder hereof as the
absolute  owner of this  Warrant  Certificate  (notwithstanding  any notation of
ownership or other writing hereon made by anyone other than the Company) for the
purpose of any exercise hereof and for notices and for all other  purposes,  and
the Company shall not be affected by any notice to the contrary.




728538.3
                                       -2-

<PAGE>



         No Warrant may be  exercised  after 5:00 P.M.,  New York City time,  on
September 14, 2003,  and to the extent not exercised by such time,  all Warrants
evidenced hereby shall become void.

         WITNESS the  corporate  seal of the Company and the  signatures  of its
duly authorized officer.

                                HEMASURE INC.
(Seal)

                                By:    /s/ James B. Murphy
                                       ------------------------------------
                                       Senior VP Finance and Administration


728538.3
                                       -3-

<PAGE>


                                  PURCHASE FORM

             (To be completed and executed upon exercise of Warrant)


To HEMASURE INC.

                  The  undersigned  hereby  irrevocably  elects to exercise  the
right of purchase  represented  by the within  Warrant  Certificate  for, and to
purchase  thereunder,  _______ shares of Common Stock,  as provided for therein,
and [tenders herewith payment of the purchase price in full in the form of [cash
or a certified  or official  bank check in the amount of $ ] or [an  election to
purchase such shares of Common Stock pursuant to the net issuance  provisions of
Section 3, clause (ii), of the Warrant Agreement.]

                  Please issue a certificate or certificates  for such shares of
Common Stock in the name of, and pay any cash for any fractional share to:

Name:   _______________________________________________________________________

Address: ______________________________________________________________________

Social Security or Tax I.D. Number: ___________________________________________

                                 (Please Print)


                                    Signature _________________________________

                                    NOTE:   The   above   signature
                                    should correspond  exactly with
                                    the  name  on the  face of this
                                    Warrant Certificate or with the
                                    name of assignee  appearing  in
                                    the assignment form below.

And, if said number of shares shall not be all the shares  purchasable under the
within  Warrant  Certificate,  a new Warrant  Certificate is to be issued in the
name of said  undersigned  for the balance  remaining of the shares  purchasable
thereunder less any fraction of a share paid in cash.


Dated:                      ,      .


728538.3
                                      -4-