WARRANT TOPURCHASE COMMON STOCK OF LIPID SCIENCES, INC.

Exhibit 4.2

Exhibit B to

Securities Purchase Agreement

THIS WARRANT AND THE SECURITIES ISSUABLE UPON EXERCISE OF THIS WARRANT HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR ANY STATE SECURITIES LAW, AND MAY NOT BE OFFERED FOR SALE, SOLD OR TRANSFERRED UNLESS A REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS SHALL BE EFFECTIVE WITH RESPECT THERETO, OR AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS IS AVAILABLE IN CONNECTION WITH SUCH OFFER, SALE OR TRANSFER. SUBJECT TO COMPLIANCE WITH THE REQUIREMENTS OF THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS, THIS WARRANT AND THE SECURITIES ISSUABLE UPON EXERCISE OF THIS WARRANT MAY BE PLEDGED OR HYPOTHECATED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN SECURED BY THIS WARRANT OR ANY OF THE SECURITIES ISSUABLE UPON EXERCISE OF THIS WARRANT.

WARRANT TO PURCHASE COMMON STOCK

OF

LIPID SCIENCES, INC.

THIS CERTIFIES that                             (the “Holder”) of this Series B Warrant (this “Warrant”), has the right to purchase from LIPID SICENCES, INC., a Delaware corporation (the “Company”), up to              fully paid and nonassessable shares of the Company’s common stock, par value $0.001 per share (the “Common Stock”), subject to adjustment as provided herein, at a price per share equal to the Exercise Price (as defined below), at any time beginning on the date on which this Warrant is issued (the “Issue Date”) and ending at 5:00 p.m., New York City time, on the date that is ninety (90) days after the Effective Date (the “Expiration Date”).  This Warrant is issued pursuant to a Securities Purchase Agreement, dated as of September 28, 2005 (the “Securities Purchase Agreement”).  Capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Securities Purchase Agreement.

1.             Exercise.

(a)           Right to Exercise; Exercise Price.  Subject to the terms and conditions set forth herein, the Holder shall have the right to exercise this Warrant at any time and from time to time during the period beginning on the Issue Date and ending on the Expiration Date as to all or any part of the shares of Common Stock covered hereby (the “Warrant Shares”).  The “Exercise Price” for each Warrant Share purchased by the Holder upon the exercise of this Warrant shall be equal to $3.73 (subject to adjustment for the events specified in Section 5 of this Warrant).

(b)           Exercise Notice.  In order to exercise this Warrant, the Holder shall deliver, at any time prior to 5:00 p.m. New York City time on the Business Day on which the Holder wishes to effect such exercise (the “Exercise Date”), to the Company an executed copy of the notice of exercise in the form attached hereto as Exhibit A (the “Exercise Notice”), the original Warrant and the Exercise Price.  The Exercise Notice shall also state the name or names (with address) in which the shares of Common Stock that are issuable on such exercise shall be issued.  In the case of a dispute as to the calculation of the Exercise Price or the number of Warrant Shares issuable hereunder (including, without limitation, the calculation of any adjustment pursuant to Section 5 of this Warrant), the Company shall promptly issue to the Holder the number of Warrant Shares that are not disputed and shall submit the disputed calculations to a certified public accounting firm of national recognition (other than the Company’s independent accountants) promptly following the date on which the Exercise Notice is delivered to the Company.  The Company shall cause such accountant to calculate the Exercise Price and/or the number of Warrant Shares issuable hereunder and to notify the Company and the Holder of the results in writing within no later than ten (10) Business Days following the day on which such accountant received the disputed calculations (the “Dispute Procedure”).  Such accountant’s calculation shall be deemed conclusive absent manifest error.  The fees of any such accountant shall be borne by the party whose calculations were most at variance with those of such accountant.

(c)           Holder of Record.  The Holder shall, for all purposes, be deemed to have become the holder of record of the Warrant Shares specified in an Exercise Notice as of 5:00 p.m. New York City time on the Exercise Date, irrespective of the date of delivery of such Warrant Shares.  Except as specifically provided herein, nothing in this Warrant shall be construed as conferring upon the Holder hereof any rights as a stockholder of the Company prior to the Exercise Date.

(d)           Cancellation of Warrant.  This Warrant shall be canceled upon its exercise and, if this Warrant is exercised in part, the Company shall, at the time that it delivers Warrant Shares to the Holder pursuant to such exercise as provided herein, issue a new warrant, and deliver to the Holder a certificate representing such new warrant, with terms identical in all respects to this Warrant (except that such new warrant shall be exercisable into the number of shares of Common Stock with respect to which this Warrant shall remain unexercised); provided, however, that the Holder shall be entitled to exercise all or any portion of such new warrant at any time following the time at which this Warrant is exercised, regardless of whether the Company has actually issued such new warrant or delivered to the Holder a certificate therefor.

2.             Delivery of Warrant Shares Upon Exercise.  Upon exercise pursuant to Section 1 of this Warrant, the Company shall deliver within a reasonable time, not exceeding (A) the close of

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business on the third (3rd) Business Day following the Exercise Date and (B) with respect to Warrant Shares that are the subject of a Dispute Procedure, the close of business on the third (3rd) Business Day following the determination made pursuant to Section 1(b) of this Warrant (each of the dates specified in (A) and (B) being referred to as a “Delivery Date”), issue and deliver or caused to be delivered to the Holder the number of Warrant Shares as shall be determined as provided herein.  The Company shall effect delivery of Warrant Shares to the Holder by, as long as the Transfer Agent participates in the Depository Trust Company (“DTC”) Fast Automated Securities Transfer program (“FAST”), crediting the account of the Holder or its nominee at DTC (as specified in the applicable Exercise Notice) with the number of Warrant Shares required to be delivered, no later than the close of business on such Delivery Date.  In the event that the Transfer Agent is not a participant in FAST, or if the Warrant Shares are not otherwise eligible for delivery through FAST, or if the Holder so specifies in an Exercise Notice or otherwise in writing on or before the Exercise Date, the Company shall effect delivery of Warrant Shares by delivering to the Holder or its nominee physical certificates representing such Warrant Shares, no later than the close of business on such Delivery Date.  The certificates representing the Warrant Shares may bear legends in accordance with the Securities Purchase Agreement or applicable law.

3.             Failure to Deliver Warrant Shares.

(a)           In the event that the Company fails for any reason to deliver to the Holder the number of Warrant Shares specified in the applicable Exercise Notice on or before the Delivery Date therefor (an “Exercise Default”), the Company shall pay to the Holder payments (“Exercise Default Payments”) in the amount of (i) (N/365) multiplied by (ii) the aggregate Exercise Price of the Warrant Shares which are the subject of such Exercise Default multiplied by (iii) the lower of twelve percent (12%) per annum and the maximum rate permitted by applicable law (the “Default Interest Rate”), where “N” equals the number of days elapsed between the original Delivery Date of such Warrant Shares and the date on which all of such Warrant Shares are issued and delivered to the Holder.  Cash amounts payable hereunder shall be paid on or before the fifth (5th) Business Day of each calendar month following the calendar month in which such amount has accrued.  Notwithstanding anything in this Warrant to the contrary, the Company is not obligated to issue any shares in excess of the Holder’s Allocation Amount (as defined in Section 4(b) of this Warrant), the failure to deliver such Warrant Shares shall not be an Exercise Default, and no Exercise Default Payment shall be due with regards to such Warrant Shares.

(b)           In the event that the Holder has not received certificates representing the Warrant Shares on or before the Delivery Date, the Holder may, upon written notice to the Company (an “Exercise Default Notice”), regain on the date of such notice the rights of the Holder under the exercised portion of this Warrant that is the subject of such Exercise Default.  In such event, the Holder shall retain all of the Holder’s rights and remedies with respect to the Company’s failure to deliver such Warrant Shares (including without limitation the right to receive the cash payments specified in Section 3(a) of this Warrant).

(c)           The Holder’s rights and remedies hereunder are cumulative, and no right or remedy is exclusive of any other.  In addition to the amounts specified herein, the Holder shall have the right to pursue all other remedies available to it at law or in equity (including, without limitation, a decree of specific performance and/or injunctive relief).  Nothing herein shall limit the Holder’s right to

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pursue actual damages for the Company’s failure to issue and deliver Warrant Shares on the applicable Delivery Date.

4.             Exercise Limitations.

(a)           In no event shall a Holder be permitted to exercise this Warrant, or part hereof, if, upon such exercise the number of shares of Common Stock beneficially owned by the Holder (other than shares which would otherwise be deemed beneficially owned except for being subject to a limitation on exercise analogous to the limitation contained in this Section 4(a)), would exceed 4.99% of the number of shares of Common Stock then issued and outstanding.  As used herein, beneficial ownership shall be determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended, and the rules thereunder.  To the extent that the limitation contained in this Section 4(a) applies, the submission of an Exercise Notice by the Holder shall be deemed to be the Holder’s representation that this Warrant is exercisable pursuant to the terms hereof and the Company shall be entitled to rely on such representation without making any further inquiry as to whether this Section 4(a) applies.  Nothing contained herein shall be deemed to restrict the right of a Holder to exercise this Warrant, or part thereof, at such time as such exercise will not violate the provisions of this Section 4(a).  This Section 4(a) may not be amended unless such amendment is approved by the holders of a majority of the Common Stock then outstanding; provided, however, that the limitations contained in this Section 4(a) shall cease to apply (x) upon thirty (30) days’ prior written notice from the Holder to the Company, or (y) immediately upon written notice from the Holder to the Company at any time after the public announcement or other disclosure of a Major Transaction (as defined in Section 5(c) of this Warrant).

(b)           Notwithstanding anything to the contrary in this Warrant, the Series A Warrant or the Securities Purchase Agreement, no Holder shall be entitled to receive at any time upon exercise of this Warrant a number of Warrant Shares that when added to (i) the number of Warrant Shares previously received by such Holder upon exercise of this Warrant plus (ii) the number of shares of Common Stock previously purchased by such Holder pursuant to the Securities Purchase Agreement plus (iii) the number of shares of Common Stock previously received by such Holder upon exercise of its Series B Warrant, would exceed the product of (A) the Cap Amount and (B) such Holder’s Pro Rata Share (such product, the “Allocation Amount”).  In the event that any Investor to which this Warrant was originally issued shall sell or otherwise transfer any part of this Warrant, the remaining Warrant Shares allocable to such transferring Investor’s Allocation Amount shall be allocated between the transferring Investor and the transferee in proportion to amount of this Warrant being transferred.

5.             Anti-Dilution Adjustments; Distributions; Other Events.  The Exercise Price and the number of Warrant Shares issuable hereunder shall be subject to adjustment from time to time as provided in this Section 5.

(a)           Subdivision or Combination of Common Stock.  If the Company, at any time after the Issue Date, subdivides (by any stock split, stock dividend, recapitalization, reorganization, reclassification or otherwise) its outstanding Common Stock or (ii) subdivides its outstanding shares of Common Stock into a greater number of shares, then after the date of record for effecting such subdivision, the Exercise Price in effect immediately prior to such subdivision will be proportionately reduced.  If the Company, at any time after the Issue Date, combines (by reverse

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stock split, recapitalization, reorganization, reclassification or otherwise) its shares of Common Stock into a smaller number of shares, then, after the date of record for effecting such combination, the Exercise Price in effect immediately prior to such combination will be proportionally increased.

(b)           Distributions.  If the Company shall declare or make any distribution of its assets (or rights to acquire its assets) to holders of Common Stock as a partial liquidating dividend or otherwise (including any dividend or distribution to the Company’s stockholders in cash or shares (or rights to acquire shares) of capital stock of a subsidiary) (a “Distribution”), the Company shall deliver written notice of such Distribution (a “Distribution Notice”) to the Holder at least twenty (20) Business Days prior to the earlier to occur of (i) the record date for determining stockholders entitled to such Distribution (the “Record Date”) and (ii) the date on which such Distribution is made (the “Distribution Date”).  The Holder shall be entitled to a reduction in the Exercise Price as of the Record Date therefor, such reduction to be effected by reducing the Exercise Price in effect on the Business Day immediately preceding the Record Date by an amount equal to the fair market value of the assets to be distributed divided by the number of shares of Common Stock as to which such Distribution is to be made, such fair market value to be reasonably determined in good faith by the independent members of the Company’s Board of Directors.

(c)           Major Transactions.  In the event of a merger, consolidation, business combination, tender offer, exchange of shares, recapitalization, reorganization, redemption or other similar event, as a result of which shares of Common Stock shall be changed into the same or a different number of shares of the same or another class or classes of stock or securities or other assets of the Company or another entity or the Company shall sell all or substantially all of its assets (each of the foregoing being a “Major Transaction”), the Company will give the Holder at least twenty (20) Trading Days’ written notice prior to the earlier of (I) the closing or effectiveness of such Major Transaction and (II) the record date for the receipt of such shares of stock or securities or other assets, and the Holder shall be permitted to exercise this Warrant in whole or in part at any time prior to the record date for the receipt of such consideration and shall be entitled to receive, for each share of Common Stock issuable to the Holder upon such exercise, the same per share consideration payable to the other holders of Common Stock in connection with such Major Transaction.  If and to the extent that the Holder retains this Warrant or any portion hereof following such record date, the Company will cause the surviving or, in the event of a sale of assets, purchasing entity, as a condition precedent to such Major Transaction, to assume the obligations of the Company with respect to this Warrant, with such adjustments to the Exercise Price and the securities covered hereby as may be necessary in order to preserve the economic benefits of this Warrant to the Holder.  The failure to give any notice required by this Section 5(c) or any defect therein shall not affect the legality or validity of any Major Transaction or the vote upon any such action.

(d)           Adjustments; Additional Shares, Securities or Assets.  In the event that at any time, as a result of an adjustment made pursuant to this Section 5, the Holder of this Warrant shall, upon exercise of this Warrant, become entitled to receive securities or assets (other than Common Stock) then, wherever appropriate, all references herein to shares of Common Stock shall be deemed to refer to and include such shares and/or other securities or assets; and thereafter the number of such shares and/or other securities or assets shall be subject to adjustment from time to time in a manner and upon terms as nearly equivalent as practicable to the provisions of this Section 5.  Any adjustment made herein that results in a decrease in the Exercise Price shall also effect a

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proportional increase in the number of shares of Common Stock into which this Warrant is exercisable.

(e)           Board Discretion.  Notwithstanding any provision in this Warrant to the contrary, subject to the prior written consent of the Holder, the Board of Directors has the right to reduce the Exercise Price and/or increase the number of Warrant Shares issuable under this Warrant at any time or from time to time in its sole and absolute discretion.

6.             Fractional Interests.

No fractional shares or scrip representing fractional shares shall be issuable upon the exercise of this Warrant.  If, on exercise of this Warrant, the Holder hereof would be entitled to a fractional share of Common Stock or a right to acquire a fractional share of Common Stock, the Company shall, in lieu of issuing any such fractional share, pay to the Holder an amount in cash equal to the product resulting from multiplying such fraction by the Market Price as of the Exercise Date.

7.             Transfer of this Warrant.

The Holder may sell, transfer, assign, pledge or otherwise dispose of this Warrant, in whole or in part, as long as such sale or other disposition is made pursuant to an effective registration statement or an exemption from the registration requirements of the Securities Act, and applicable state security laws, and is otherwise made in accordance with the applicable provisions of the Securities Purchase Agreement.  Upon such transfer or other disposition, the Holder shall deliver this Warrant to the Company together with a written notice to the Company, substantially in the form of the Transfer Notice attached hereto as Exhibit B (the “Transfer Notice”), indicating the person or persons to whom this Warrant shall be transferred and, if less than all of this Warrant is transferred, the number of Warrant Shares to be covered by the part of this Warrant to be transferred to each such person.  Within three (3) Business Days of receiving a Transfer Notice and the original of this Warrant, the Company shall deliver to the transferee designated by the Holder a Warrant or Warrants of like tenor and terms for the appropriate number of Warrant Shares and, if less than all this Warrant is transferred, shall deliver to the Holder a Warrant for the remaining number of Warrant Shares.

8.             Benefits of this Warrant.

This Warrant shall be for the sole and exclusive benefit of the Holder of this Warrant and nothing in this Warrant shall be construed to confer upon any person other than the Holder of this Warrant any legal or equitable right, remedy or claim hereunder.

9.             Loss, Theft, Destruction or Mutilation of Warrant.

Upon receipt by the Company of evidence of the loss, theft, destruction or mutilation of this Warrant, and (in the case of loss, theft or destruction) of indemnity reasonably satisfactory to the Company, and upon surrender of this Warrant, if mutilated, the Company shall execute and deliver a new Warrant of like tenor and date.

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10.           Notice or Demands.

Any notice, demand or request required or permitted to be given by the Company or the Holder pursuant to the terms of this Warrant shall be in writing and shall be deemed delivered (i) when delivered personally or by verifiable facsimile transmission, unless such delivery is made on a day that is not a Business Day, in which case such delivery will be deemed to be made on the next succeeding Business Day and (ii) on the Business Day actually received if deposited in the U.S. mail (certified or registered mail, return receipt requested, postage prepaid) or sent via overnight courier, addressed as follows:

If to the Company:

Lipid Sciences, Inc.

7068 Koll Center Parkway

Ste 401

Pleasanton, CA 94566

Attn:  Sandra Gardiner

C hief Financial Officer

Tel:  (925) 249-4000

Fax:  (925) 249-4080

with a copy (which shall not constitute notice) to:

Shearman & Sterling LLP

1080 Marsh Road

Menlo Park, CA 94025

Attn: James B. Bucher

Tel: (650) 838-3737

Fax: (650) 838-3699

and if to the Holder, to such address as shall be designated by the Holder in writing to the Company.

11.           Applicable Law.

This Warrant is issued under and shall for all purposes be governed by and construed in accordance with the laws of the State of New York applicable to contracts made and to be performed entirely within the State of New York.

12.           Amendments.

No amendment, modification or other change to, or waiver of any provision of, this Warrant may be made unless such amendment, modification or change is (A) set forth in writing and is signed by the Company and the Holder and (B) agreed to in writing by the holders of at least

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two-thirds (2/3) of the number of shares into which the Warrants are exercisable (without regard to any limitation contained herein on such exercise), it being understood that upon the satisfaction of the conditions described in (A) and (B) above, each Warrant (including any Warrant held by the Holder who did not execute the agreement specified in (B) above) shall be deemed to incorporate any amendment, modification, change or waiver effected thereby as of the effective date thereof.

13.           Entire Agreement.

This Warrant and the other Transaction Documents constitute the entire agreement and supersede all prior agreements and understandings among the parties hereto with respect to the subject matter hereof and thereof.

14.           Headings.

The headings in this Warrant are for convenience of reference only and shall not limit or otherwise affect the meaning hereof.

15.           Restrictions.

The Holder acknowledges that the shares acquired upon exercise of this Warrant, if not registered, will have restrictions upon resale imposed by state and federal securities laws.

16.           Successors and Assigns.

Subject to applicable securities laws, this Warrant and the rights and obligations evidenced hereby shall inure to the benefit of and be binding upon the successors of the Company and the successors and permitted assigns of the Holder.

[Signature Page to Follow]

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IN WITNESS WHEREOF, the Company has duly executed and delivered this Warrant as of the Issue Date.

EXHIBIT A to WARRANT

EXERCISE NOTICE

The undersigned Holder hereby irrevocably exercises the right to purchase                    of the shares of Common Stock (“Warrant Shares”) of LIPID SCIENCES, INC. evidenced by the attached Warrant (the “Warrant”).  Capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Warrant.

EXHIBIT B to WARRANT

TRANSFER NOTICE

FOR VALUE RECEIVED, the undersigned Holder of the attached Warrant hereby sells, assigns and transfers unto the person or persons named below the right to purchase                shares of the Common Stock of LIPID SCIENCES, INC. evidenced by the attached Warrant.  By signing this Transfer Notice, the transferee agrees to be legally bound by the terms of the attached Warrant and of the related Securities Purchase Agreement and Registration Rights Agreement applicable to an Investor.