<PAGE>

                                                                     EXHIBIT 4.8

                              WARRANT CERTIFICATE


          THIS WARRANT AND ANY SHARES ACQUIRED UPON THE EXERCISE HEREOF HAVE NOT
BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED, OR
UNDER ANY APPLICABLE STATE SECURITIES LAWS.  THIS WARRANT AND SUCH SHARES AND
ANY INTEREST OR PARTICIPATION HEREIN OR THEREIN MAY NOT BE SOLD OR TRANSFERRED
IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM EXCEPT UPON THE
CONDITIONS SPECIFIED IN THIS WARRANT, AND NO TRANSFER OF THIS WARRANT OR SUCH
SHARES SHALL BE VALID OR EFFECTIVE UNLESS AND UNTIL SUCH CONDITIONS SHALL HAVE
BEEN COMPLIED WITH.

          THIS WARRANT AND ANY SHARES ACQUIRED UPON THE EXERCISE HEREOF ARE
SUBJECT TO ALL THE TERMS AND CONDITIONS OF A CERTAIN STOCKHOLDERS AGREEMENT,
DATED AS OF DECEMBER 4,1996, AMONG CARESIDE, INC.  AND ITS STOCKHOLDERS, A COPY
OF WHICH THE COMPANY WILL FURNISH TO THE HOLDER OF THIS WARRANT UPON REQUEST AND
WITHOUT CHARGE.

                         WARRANT CERTIFICATE NO. SR-2
                     to Purchase Shares of Common Stock of
                                CARESIDE, INC.
                                 June 21, 1999

          THIS CERTIFIES THAT, for good and valuable consideration comprised of,
inter alia, the surrender of Warrant Certificate SR-1 which is hereby cancelled,
----------
the receipt and sufficiency of which is hereby acknowledged, S.R.One, Limited, a
Pennsylvania Business Trust, or its permitted assigns (the "Holder"), is the
registered owner of this Warrant Certificate (the "Warrant"), subject to the
terms and conditions hereinafter set forth.

          This Warrant is issued pursuant to the Securities Purchase Agreement
dated as of December 17, 1998, between the Holder and the Company (the
"Securities Purchase Agreement"), pursuant to which the Company agreed to issue
and sell to the Holder, and the Holder agreed to purchase promissory notes, each
with a detachable warrant to purchase shares of the Company's Common Stock, and
as modified by the Securities Conversion Agreement dated as of June 14, 1999
between the Holder and the Company (the "Securities Conversion Agreement")
pursuant to which one-third of the promissory notes were converted into shares
of Series A Convertible Preferred Stock of the Company.  Capitalized terms used
and not defined herein have the meanings set forth in the Securities Conversion
Agreement.
<PAGE>

     1    Grant.  This Warrant grants to the Holder the right to purchase, on or
          -----
after the earlier of (i) December 17, 1999 or (ii) six months after the
completion of the Initial Public Offering of the Units and until 5:30 p.m., New
York time, on the earlier of (a) the seventh anniversary of the date of issuance
of this Warrant or (b) four years from the closing of an Initial Public
Offering, an aggregate number of shares of Common Stock ("Warrant Shares")
determined by dividing One Million Five Hundred Thousand Dollars ($1,500,000) by
either (i) $ 1.40, or (ii) if an Initial Public Offering of the Units has
occurred, eighty-five percent (85%) of the price per Unit at which the Unit is
first sold to the public in the Initial Public Offering (before discounts and
commissions) (the "Unit Price").

     2    Exercise of Warrant.
          -------------------

          2.1. Exercise. This Warrant shall be exercisable at any time in whole
               --------
and not in part. The aggregate exercise price for the purchase of the Warrant
Shares ("Exercise Price") shall be equal to eighty-five percent (85%) of the
Unit Price multiplied by the number of Warrant Shares. This Warrant may be
exercised by surrender of this Warrant with the annexed Form of Election to
Purchase duly executed, together with payment of the Exercise Price multiplied
by the number of Warrant Shares, at the Company's principal offices located at
6100 Bristol Parkway, Culver City, CA 90230. The Exercise Price shall be payable
by certified or official bank check or wire transfer of immediately available
funds. For purposes hereof, "Exercise Date" shall mean the date on which all
deliveries required to be made to the Company upon exercise of this Warrant
pursuant to this Section 2.1 shall have been made.

          2.2. Issuance of Certificates for Warrant Shares. Upon the exercise of
               -------------------------------------------
the Warrants, the issuance of certificates for Warrant Shares shall be made
forthwith (and in any event such issuance shall be made within ten (10) business
days after the Exercise Date) without charge to the Holder including, without
limitation, any tax which may be payable in respect of the issuance thereof, and
such certificates shall (subject to the provisions of Section 3 hereof) be
issued in the name of, or in such names as may be directed by, the Holder
thereof; provided, however, that the Company shall not be required to pay any
tax which may be payable in respect of any transfer involved in the issuance and
delivery of any such certificates in a name other than that of the Holder, and
the Company shall not be required to issue or deliver such certificates unless
or until the person or persons requesting the issuance thereof shall have paid
to the Company the amount of such tax or shall have established to the
satisfaction of the Company that such tax has been paid.

     3    Transfer of Securities.  The Holder, by acceptance of this Warrant
          ----------------------
Certificate, covenants and agrees that it is acquiring this Warrant and, upon
exercise hereof, the Warrant Shares, for its own account, as an investment and
not with a view to distribution thereof.  The Warrant Shares have not been
registered under the Securities Act of 1933, as amended (the "Act") or any state
securities laws and no transfer of any Warrant Shares shall be permitted unless
the Company has received notice of such transfer, at the address of its
principal office, in the form of the Assignment attached hereto, accompanied by
an opinion of counsel reasonably satisfactory

                                      -2-
<PAGE>

to the Company that an exemption from registration of such Warrants Shares under
the Act is available for such transfer. Upon any exercise of this Warrant,
certificates representing the Warrant Shares and any of the other securities
issuable upon exercise of this Warrant shall bear the following legend:

               The securities represented by this certificate have not
               been registered under the Securities Act of 1933
               ("Act") or any state securities laws for public resale,
               and may not be offered or sold except pursuant to (i)
               an effective registration statement under the Act and
               such laws or (ii) an opinion of counsel satisfactory to
               the issuer that an exemption from such registration is
               available.

Any purported transfer of this Warrant or any Warrant Shares not in compliance
with the provisions of this Section 3 shall be null and void.

          4    Adjustments to Unit Price and Number of Securities.
               --------------------------------------------------

               4.1. Computation of Adjusted Unit Price. Except as hereinafter
                    ----------------------------------
provided, in case the Company shall at any time after the date hereof issue or
sell any shares of Common Stock, including, without limitation, shares held in
the Company's treasury and shares of Common Stock issued upon the exercise of
any options, rights or warrants to subscribe for shares of Common Stock and
shares of Common Stock issued upon the direct or indirect conversion or exchange
of securities for shares of Common Stock, for a consideration per share less
than the Unit Price, then forthwith upon such issuance or sale, the Unit Price
shall (until another such issuance or sale) be reduced to an amount equal to (i)
the sum of (A) the number of shares of Common Stock outstanding immediately
prior to such issuance or sale multiplied by the then existing Unit Price, and
(B) the aggregate amount of the consideration, if any, received by the Company
upon such issuance or sale, divided by (ii) the total number of shares of Common
Stock outstanding immediately after such issuance or sale; provided, however,
that in no event shall the Unit Price be adjusted pursuant to the computations
in this Section 4.1 to an amount in excess of the Unit Price in effect
immediately prior to such computation, except in the case of a combination of
outstanding shares of Common Stock, as provided by Section 4.3 hereof.

          For the purposes of any computation to be made in accordance with this
Section 4.1, the following provisions shall be applicable:

                         (i)  In case of the issuance or sale of shares of
Common Stock for a consideration part or all of which shall be cash, the amount
of the cash consideration therefor shall be deemed to be the amount of cash
received by the Company for such shares (or, if shares of Common Stock are
offered by the Company for subscription, the subscription price, or, if shares
of Common Stock are sold to underwriters or dealers for public offering without
a

                                      -3-
<PAGE>

subscription offering, the public offering price, before deducting therefrom any
compensation paid or discount allowed in the sale, underwriting or purchase
thereof by underwriters or dealers or others performing similar services, or any
expenses incurred in connection therewith) plus any amounts payable to security
holders or any affiliate thereof, including without limitation employment
agreement, royalty, consulting agreement, covenant not to compete agreement
pursuant to any or contingent payment right or similar arrangement, agreement or
understanding, whether oral or written; all such amounts shall be valued at the
aggregate amount payable thereunder whether such payments are absolute or
contingent and irrespective of the period or uncertainty of payment, the rate of
interest, if any, or the contingent nature thereof except if the payment of such
amounts has been approved by the Holder.

                    (ii)  In case of the issuance or sale (otherwise than as a
dividend or other distribution on any stock of the Company) of shares of Common
Stock for a consideration part or all of which shall be other than cash, the
amount of the consideration therefor other than cash shall be deemed to be the
value of such consideration as determined in good faith by the Board of
Directors of the Company.

                    (iii) Shares of Common Stock issuable by way of dividend or
other distribution on any stock of the Company shall be deemed to have been
issued immediately after the opening of business on the day following the record
date for the determination of stockholders entitled to receive such dividend or
other distribution and shall be deemed to have been issued without
consideration.

                    (iv)  The reclassification of securities of the Company
other than shares of Common Stock into securities including shares of Common
Stock shall be deemed to involve the issuance of such shares of Common Stock for
a consideration other than cash immediately after the opening of business on the
day following the record date for the determination of security holders entitled
to receive such shares, and the value of the consideration allocable to such
shares of Common Stock shall be determined as provided in subsection (ii) of
this Section 4. 1.

                    (v)   The number of shares of Common Stock at any one time
outstanding shall include the aggregate number of shares issued or issuable
(subject to readjustment upon the actual issuance thereof) upon the exercise of
then outstanding options, rights, warrants and upon the conversion or exchange
of then outstanding convertible or exchangeable securities.

                    (vi)  No adjustment shall be made to the Unit Price then in
effect upon the exercise of any warrant or conversion of any Series A
Convertible Preferred Stock ("Preferred Stock") issued pursuant to the
Securities Purchase Agreement or Securities Conversion Agreement or the
conversion or exchange of convertible or exchangeable securities outstanding as
of the date of execution of the Securities Conversion Agreement.

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<PAGE>

          4.2. Options, Rights, Warrants and Convertible and Exchangeable
               ----------------------------------------------------------
Securities. In case the Company shall at any time after the date hereof grant or
----------
issue options, rights or warrants to subscribe for shares of Common Stock, or
issue any securities convertible into or exchangeable for shares of Common
Stock, where the aggregate consideration per share is less than the Unit Price
in effect immediately prior to the issuance of such options, rights or warrants,
or such convertible or exchangeable securities, the Unit Price in effect
immediately prior to the issuance of such options, rights or warrants, or such
convertible or exchangeable securities, as the case may be, shall be reduced to
a price determined by making a computation in accordance with the provisions of
Section 4.1 hereof, provided that:

               (a)  The aggregate maximum number of shares of Common Stock, as
the case may be, issuable under such options, rights or warrants shall be deemed
to be issued and outstanding at the time such options, rights or warrants were
issued.

               (b)  The aggregate consideration for any such options, rights or
warrants shall be equal to the minimum purchase price per share provided for in
such options, rights or warrants at the time of issuance, plus the
consideration, if any, received by the Company for such options, rights or
warrants.

               (c)  The aggregate maximum number of shares of Common Stock
issuable upon conversion or exchange of any convertible or exchangeable
securities shall be deemed to be issued and outstanding at the time of issuance
of such securities.

               (d)  The aggregate consideration for any such convertible or
exchangeable securities shall be equal to the consideration received by the
Company for such securities, plus the total consideration, if any, receivable by
the Company upon the conversion or exchange thereof.

               (e)  If any change shall occur in the exercise price per share
provided for in any of such options, rights or warrants or in the price per
share at which such convertible or exchangeable securities are convertible or
exchangeable, such options, rights or warrants or convertible or exchangeable
securities, as the case may be, shall be deemed to have expired or terminated on
the date when such price change became effective in respect of shares not
theretofore issued pursuant to the exercise or conversion or exchange thereof,
and the Company shall be deemed to have issued upon such date new options,
rights or warrants or convertible or exchangeable securities at the new price in
respect of the number of shares issuable upon the exercise of such options,
rights or warrants or the conversion or exchange of such convertible or
exchangeable securities.

               (f)  In case there has been any adjustment hereunder in the Unit
Price by reason of the offer, issue or sale of any subscription or purchase
rights or options or any convertible or exchangeable securities or obligations
and the purchase, conversion or exchange

                                      -5-
<PAGE>

privilege so created thereafter terminates unexercised or changes, such Unit
Price shall as of the date of such termination or change be adjusted to reflect
such termination or change.

          4.3. Subdivision and Combination. In case the Company shall at any
               ---------------------------
time subdivide or combine the outstanding shares of Common Stock, the Unit Price
shall forthwith be proportionately decreased in the case of subdivision or
increased in the case of combination.

          4.4. Adjustment in Number of Securities. Upon each adjustment of the
               ----------------------------------
Unit Price pursuant to the provisions of this Section 4, the number of Warrant
Shares issuable on exercise of this Warrant shall be adjusted to the nearest
full amount by multiplying a number equal to the Unit Price in effect
immediately prior to such adjustment by the number of Warrant Shares issuable
upon exercise of this Warrant immediately prior to such adjustment and dividing
the product so obtained by the adjusted Unit Price.

          4.5. Definition of Common Stock. For the purpose of this Agreement,
               --------------------------
the term "Common Stock" shall mean (i) the class of stock designated as Common
Stock in the Certificate of Incorporation of the Company as may be amended after
the date hereof, or (ii) any other class of stock resulting from successive
changes or modifications of such Common Stock consisting solely of changes in
par value, or from par value to no par value, or from no par value to par value.

          4.6. Merger or Consolidation. In the event there is proposed any
               -----------------------
consolidation of the Company with, or merger of the Company with or into,
another corporation, other than a merger or consolidation in which the Company
is the surviving corporation and after which at least fifty percent (50%) of the
outstanding voting securities of the Company are owned by the stockholders of
the Company immediately prior to such merger or consolidation, subject to its
obligations of confidentiality, the Company shall provide the Holder with not
less than 30 days' prior written notice of the proposed effective date of such
merger or consolidation (the "Effective Date"). The Holder shall be entitled to
exercise its Warrants at any time up to the third business day prior to the
Effective Date, and this Warrant shall, if not so exercised, terminate and be of
no further force and effect on the Effective Date (or such later date on which
the merger or consolidation becomes effective). Any such exercise by the Holder
may be conditioned upon and made subject to the consummation of the merger or
consolidation.

          4.7. No Adjustment of Exercise Price in Certain Cases. No adjustment
               ------------------------------------------------
of the Exercise Price shall be made:

               (a)  Upon the issuance or sale of this Warrant or the other
warrants pursuant to the Securities Purchase Agreement and the Securities
Conversion Agreement or the shares of Common Stock issuable upon the exercise of
this Warrant or such other warrants.

                                      -6-
<PAGE>

               (b)  Upon the issuance or conversion, sale of shares of Preferred
Stock or the issuance of warrants upon conversion of shares of Preferred stock
or upon the issuance of shares of Common Stock pursuant to exercise of such
warrants.

               (c)  If the amount of said adjustment shall be less than two
cents (24) per Warrant Share; provided, however, that in such case any
adjustment that would otherwise be required then to be made shall be carried
forward and shall be made at the time of and together with the next subsequent
adjustment which, together with any adjustment so carried forward, shall amount
to at least two cents (24) per security issuable upon exercise of the Warrants.

          4.8. Dividends and Other Distributions. In the event that the Company
               ---------------------------------
shall at any time prior to the exercise of this Warrant declare a dividend
(other than a dividend consisting solely of shares of Common Stock) or otherwise
distribute to its stockholders any assets, property, rights, evidence of
indebtedness, securities (other than shares of Common Stock), whether issued by
the Company or by another, or any other thing of value, the Holder of this
Warrant shall thereafter be entitled, in addition to the shares of Common Stock
or other securities and property receivable upon the exercise thereof, to
receive, upon the exercise of this Warrant, the same property, assets, rights,
evidences of indebtedness, securities or any other thing of value that they
would have been entitled to receive at the time of such dividend or distribution
if this Warrant had been exercised immediately prior to such dividend or
distribution. At the time of any such dividend or distribution, the Company
shall make appropriate reserves to ensure the timely performance of the
provisions of this Section 4.8.

     5    Exchange and Replacement of Warrant. Upon receipt by the Company of
          -----------------------------------
evidence reasonably satisfactory to it of the loss, theft, destruction or
mutilation of this Warrant, and, in case of loss, theft or destruction, of
indemnity or security reasonably satisfactory to it, and reimbursement to the
Company of all reasonable expenses incidental thereto, and upon surrender and
cancellation of this Warrant, if mutilated, the Company will make and deliver a
new Warrant of like tenor, in lieu thereof.

     6    Elimination of Fractional Interests. The Company shall not be required
          -----------------------------------
to issue certificates representing fractions of shares of Common Stock upon the
exercise of this Warrant, but instead shall pay cash in lieu of such fractional
interests to the Holder based on the Fair Market Value of the Common Stock as
determined in good faith by the Board of Directors of the Company. For this
purpose, the "Fair Market Value" of a share of Common Stock on any day means:
(a) if the principal market for the Common Stock is The New York Stock Exchange,
American Stock Exchange or any other national securities exchange or The Nasdaq
National Market, the closing sales price of the Common Stock on such day as
reported by such exchange or market, or on a consolidated tape reflecting
transactions on such exchange or market, or (b) if the principal market for the
Common Stock is not a national securities exchange or The Nasdaq National Market
and the Common Stock is quoted on the National Association of Securities Dealers
Automated Quotations System, the mean between the closing bid and the closing
asked

                                      -7-
<PAGE>

prices for the Common Stock on such day as quoted on such System, or (c) if the
Common Stock is not quoted on the National Association of Securities Dealers
Automated Quotations System, the price therefor reported by the National
Quotation Bureau, Inc.; provided that if none of (a), (b) or (c) above is
applicable, or if no trades have been made or no quotes are available for such
day, the Fair Market Value of the Common Stock shall be determined, in good
faith, by the Board of Directors of the Company.

          7    Reservation and Listing of Securities. The Company shall at all
               -------------------------------------
times reserve and keep available out of its authorized shares of Common Stock,
solely for the purpose of issuance upon the exercise of this Warrant, such
number of shares of Common Stock or other securities, properties or rights as
shall be issuable upon the exercise thereof. The Company covenants and agrees
that, upon exercise of this Warrant and payment of the Exercise Price therefor,
all shares of Common Stock and other securities issuable upon such exercise
shall be duly and validly issued, fully paid, nonassessable and not subject to
the preemptive rights of any stockholder.

          8    Notices to Warrant Holder. Nothing contained in this Agreement
               -------------------------
shall be construed as conferring upon the Holder the right to vote or to consent
or to receive notice as a stockholder in respect of any meetings of stockholders
for the election of directors or any other matter, or as having any rights
whatsoever as a stockholder of the Company. If, however, at any time prior to
the expiration of this Warrant and its exercise, any of the following events
shall occur:

                    (a)  the Company shall take a record of the holders of its
shares of Common Stock for the purpose of entitling them to receive a dividend
or distribution payable otherwise than in cash, or a cash dividend or
distribution payable otherwise than out of current or retained earnings, as
indicated by the accounting treatment of such dividend or distribution on the
books of the Company; or

                    (b)  the Company shall offer to all the holders of its
Common Stock any additional shares of capital stock of the Company or securities
convertible into or exchangeable for shares of capital stock of the Company or
any option right or warrant to subscribe therefor; or

                    (c)  a dissolution, liquidation or winding up of the Company
(other than in connection with a consolidation or merger) or a sale, of all or
substantially all of its property, assets and business as an entirety shall be
proposed;

then, in any one or more of said events, the Company shall give written notice
of such event at least fifteen (15) days prior to the date fixed as a record
date, or the date of closing the transfer books for the determination of the
stockholders entitled to such dividend, distribution, convertible or
exchangeable securities or subscription rights, or entitled to vote on such
proposed dissolution, liquidation, winding up or sale.  Such notice shall
specify such record date or the date of closing

                                      -8-
<PAGE>

the transfer books, as the case may be. Failure to give such notice or any
defect therein shall not affect the validity of any action taken in connection
with the declaration or payment of any such dividend, or the issuance of any
convertible or exchangeable securities, or subscription rights, options or
warrants, or any proposed dissolution, liquidation, winding up or sale.

          9    Notices. All notices, requests, consents and other communications
               -------
hereunder shall be in writing and shall be deemed to have been duly made when
delivered, or mailed by registered or certified mail, return receipt requested
in accordance with Section 5.8 of the Securities Conversion Agreement.

          10   Supplements and Amendments. The Company and the Holder may from
               --------------------------
time to time supplement or amend this Warrant in writing in order to cure any
ambiguity, to correct or supplement any provision contained herein which may be
defective or inconsistent with any provision herein or to make any other
provisions in regard to matters or questions arising hereunder which the Company
and the Holder may deem necessary or desirable.

          11   Successors. All the covenants and provisions of this Warrant
               ----------
shall be binding upon and inure to the benefit of the Company, the Holder and
their respective successors and assigns hereunder.

          12   Governing Law: Submission to Jurisdiction. This Warrant shall be
               -----------------------------------------
governed by, and construed in accordance with, the laws of the State of
Delaware.

          13   Entire Agreement. The Securities Purchase Agreement, the
               ----------------
Securities Conversion Agreement, this Warrant and the promissory note issued
contemporaneously with this Warrant pursuant to the Securities Conversion
Agreement, contain the entire understanding between the parties hereto and
supersede all prior agreements and understandings, written or oral, with respect
to the subject matter hereof and thereof.

          14   Severability. If any provision of this Warrant shall be held to
               ------------
be invalid and unenforceable, such invalidity or unenforceability shall not
affect any other provision of this Warrant.

          15   Captions. The caption headings of the Sections of this Warrant
               --------
are for convenience of reference only and are not intended, nor should they be
construed, as a part of this Warrant and shall be given no substantive effect.

          16   Benefits of this Agreement. Nothing in this Warrant shall be
               --------------------------
construed to give to any person or corporation other than the Company and the
Holder of the Warrant or Warrant Shares any legal or equitable right, remedy or
claim under this Warrant; and this Warrant shall be for the sole and exclusive
benefit of the Company and the Holder.

                                      -9-
<PAGE>

          IN WITNESS WHEREOF, the Company has caused this Warrant Certificate to
be duly executed, as of the day and year first above written.

                              CARESIDE, INC.

                              By:  /s/ James Koch
                                 ------------------------------------
                                 Name: James Koch
                                 Title:  Chief Financial Officer

                                      -10-
<PAGE>

             FORM OF ELECTION TO PURCHASE PURSUANT TO SECTION 2.1

          The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant, to purchase shares of Common Stock.

          In accordance with the terms of Section 2 of Warrant No. S.R.-2 dated
as of June 21, 1999 issued by Careside, Inc. to S.R.One, Limited, the
undersigned requests that a certificate for such securities be registered in the
name of _____________________ whose address is ___________________________ and
that such Certificate be delivered to ____________________ whose address is
_____________________________________.


Dated:
                              Signature:____________________________

                              Print Name:___________________________

                              (Signature must conform in all respects to name of
                              Holder as specified on the face of the Warrant.)

                              (Insert Social Security or Other Identifying
                              Number of Holder)

                                      -11-
<PAGE>

                              FORM OF ASSIGNMENT

                 (To be executed by the Holder if such Holder
                 desires to transfer the Warrant Certificate.)

          FOR VALUE RECEIVED __________________ here sells, assigns and
transfers unto _____________________________________________________________
(Please print name and address of transferee)

this Warrant, together with all right, title and interest therein, and does
hereby irrevocably constitute and appoint _______________ Attorney, to transfer
this Warrant on the books of Careside, Inc. with full power of substitution.

Dated:
                              Signature:________________________
                              Print Name:______________________
                              (Signature must conform in all respects to name of
                              holder as specified on the face of the Warrant
                              Certificate.)


                              _________________________________
                              (Insert Social Security or Other Identifying
                              Number of Holder)

                                      -12-