Document:

EXHIBIT 10.1

                          SECURITIES PURCHASE AGREEMENT

     This SECURITIES PURCHASE AGREEMENT (this "Agreement") is made and entered
into as of March 28, 2008 (the "Closing Date") by and among ELECTRONIC SENSOR
TECHNOLOGY, INC., a Nevada corporation (the "Company"), and HALFMOON BAY CAPITAL
LTD, a British Virgin Islands company (the "Investor").

     WHEREAS, the Company desires to sell to the Investor, and the Investor
desires to purchase from the Company, shares of the Company's common stock, par
value $.001 per share (the "Common Stock"), and a convertible debenture on the
terms and conditions set forth in this Agreement and pursuant to Section 4(2) of
the Securities Act of 1933, as amended (the "Securities Act").

     NOW, THEREFORE in consideration of the mutual promises and conditions set
forth herein, and for good and valuable consideration, the adequacy and receipt
of which is hereby acknowledged, the parties hereto hereby agree as follows:

                                   SECTION 1.
                              TRANSACTION; CLOSING

     1.1    Agreement to Purchase and Sell. Subject to the terms hereof, the
Company agrees to issue and sell to the Investor, and the Investor agrees to
purchase from the Company, on the Closing Date:

            (a)     shares of Common Stock of the Company (the "Purchase
Shares") in an amount equal to (i) USD$3,500,000.00 (the "Common Stock Purchase
Price"), divided by (ii) a price per share (the "Share Price") equal to the
lesser of (A) $0.08 and (B) ninety percent (90%) of the closing quotation of the
Common Stock on the OTC Bulletin Board for the trading day preceding the Closing
Date; and

            (b)     a nine percent (9%) convertible debenture due five (5) years
from the Closing Date with a conversion price of one hundred twenty percent
(120%) of the Share Price substantially in the form attached hereto as Exhibit A
(the "Debenture") in a principal amount of USD$2,000,000.00 (collectively, with
the Common Stock Purchase Price, the "Purchase Price").

     1.2    Purchase Price. In consideration for the sale and issuance by the
Company of the Purchase Shares and the Debenture, the Investor shall pay to the
Company on the Closing Date the Purchase Price in United States Dollars by wire
transfer of immediately available funds to the following account maintained by
the Company:
<PAGE>
            East West Bank, City of Industry Branch #29
            Attention: Banking Officer:  Christopher Jin
            18645 East Gale Avenue, Suite 100
            City of Industry, CA 91748
            626-581-5090 (Telephone)
            626-913-1976 (Fax)
            ABA#3220-7038-1
            Account Number:  8290-4665

     1.3    Closing. The closing of the purchase and sale of the Purchase Shares
and Debenture hereunder (the "Closing") shall take place at the Company, located
at 1077 Business Center Circle, Newbury Park, California 91320, at 10:00 a.m.
local time on the Closing Date.

     1.4    Deliveries. Upon the Closing, the Company will deliver the Debenture
to the Investor. As soon as practicable following the Closing, the Company will
deliver or cause to be delivered to the Investor a certificate in the Investor's
name representing the Purchase Shares.

                                   SECTION 2.
                  REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     The Company hereby represents and warrants to the Investor, as of the
Closing Date, as follows:

     2.1    Organization; Good Standing; Corporate Power; Qualification. The
Company and each Subsidiary (as defined below) has been duly incorporated or
otherwise organized, and is validly existing, under the laws of its jurisdiction
of incorporation or organization. The Company and each Subsidiary that is a
corporation is in good standing under the laws of its jurisdiction of
incorporation. The Company and each Subsidiary has the requisite corporate or
organizational power and authority to own and operate its properties and assets
and to carry on its business as currently conducted. The Company and each
Subsidiary is duly qualified to do business as a foreign corporation or other
entity and in good standing in all jurisdictions in which it is required to be
qualified to do intrastate business as the businesses of the Company and the
Subsidiaries are currently conducted and as presently proposed to be conducted,
except for jurisdictions in which failure to be so qualified or in good
standing, as the case may be, could not reasonably be expected to have a
material adverse effect on (a) the business and operations of the Company and
the Subsidiaries taken as a whole, (b) the legality, validity or enforceability
of this Agreement or the Debenture or (c) the Company's ability to perform in
any material respect its obligations under this Agreement or the Debenture (any
of (a), (b) or (c), a "Material Adverse Effect").

     2.2    Subsidiaries. The Company owns, directly or indirectly, all of the
capital stock or other equity interests of each of the following: (a) Amerasia
Technology, Inc., a California corporation ("Amerasia"), (b) L&G Sensor
Technology, Inc., a California corporation ("L&G"), and (c) Electronic Sensor
Technology, L.P., a California limited partnership (which is owned approximately
55% by Amerasia and approximately 45% by L&G) (each, a "Subsidiary" and
collectively, the "Subsidiaries"), free and clear of any lien, charge, security
interest, encumbrance, right of first refusal, preemptive right or other
restriction ("Liens"), and all of the

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issued and outstanding shares of capital stock of Amerasia and L&G are validly
issued, fully paid and non-assessable. Aside from the foregoing, the Company
does not own or control, directly or indirectly, any interest in any other
corporation, partnership, trust, joint venture, association, or other entity.

     2.3    Due Authorization; Enforceability. The Company has the requisite
corporate power and authority to enter into and to consummate the transactions
contemplated by this Agreement and the Debenture and to carry out its
obligations hereunder and thereunder. The execution and delivery of this
Agreement and the Debenture by the Company and the consummation by it of the
transactions contemplated hereby and thereby have been duly authorized by all
necessary action on the part of the Company and no further action is required by
the Company, its board of directors or its stockholders in connection therewith
other than, to the extent necessary, in connection with actions to be taken
pursuant to Section 2.7. This Agreement and the Debenture have been duly
executed by the Company and, when delivered in accordance with the terms hereof
and thereof and assuming due authorization and execution of this Agreement by
the Investor, will constitute the valid and binding obligation of the Company
enforceable against the Company in accordance with its terms except (a) as
limited by applicable bankruptcy, insolvency, reorganization, moratorium and
other laws of general application affecting enforcement of creditors' rights
generally, (b) as limited by laws relating to the availability of specific
performance, injunctive relief or other equitable remedies and (c) insofar as
indemnification and contribution provisions may be limited by applicable law.

     2.4    Capitalization. The capitalization of the Company immediately prior
to the Closing, without giving effect to the issuance of the Securities, is as
set forth in the SEC Reports (as defined below). Other than as set forth in the
SEC Reports and except as a result of the issuance of the Debenture, there are
no outstanding options, warrants, rights (including conversion or preemptive
rights) or agreements for the purchase or acquisition from the Company of any
shares of its capital stock or any securities convertible into or ultimately
exchangeable or exercisable for any shares of the Company's capital stock. Apart
from the exceptions noted herein, no shares of the Company's outstanding capital
stock, or stock issuable upon exercise or exchange of any outstanding options,
warrants or rights, or other stock issuable by the Company, are subject to any
preemptive rights, rights of first refusal or other rights to purchase such
stock (whether in favor of the Company or any other person), pursuant to any
agreement or commitment of the Company.

     2.5    Securities of the Company.

            (a)     Issuance of Capital Stock. All of the outstanding shares of
the capital stock of the Company are duly authorized and validly issued, fully
paid and non-assessable, have been issued in material compliance with all
federal and applicable state securities laws, and none of such outstanding
shares was issued in violation of any preemptive rights or similar rights to
subscribe for or purchase securities.

            (b)     Issuance of the Securities. The Purchase Shares and the
Debenture are duly authorized and, when issued and paid for in accordance with
this Agreement, will be validly issued and, in the case of the Purchase Shares,
will be fully paid and non-assessable. The Company has reserved from its duly
authorized capital stock the shares of Common Stock

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issuable upon conversion of the Debenture (the "Debenture Shares"). Assuming the
accuracy of the Investor's representations and warranties set forth in Section
3, no registration under the Securities Act is required for the offer and sale
of the Purchase Shares, the Debenture or the Debenture Shares (collectively, the
"Securities") by the Company to the Investor as contemplated hereby.

            (c)     Exchange Act Registration. The Company's Common Stock is
registered pursuant to Section 12(g) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), and the Company has taken no action designed to,
or which to its knowledge is likely to have the effect of, terminating the
registration of the Common Stock under the Exchange Act nor has the Company
received any notification that the United States Securities and Exchange
Commission (the "SEC") is contemplating terminating such registration. The
Company has not, in the twelve (12) months preceding the date hereof, received
notice from the OTC Bulletin Board to the effect that the Company is not in
compliance with the listing or maintenance requirements of the OTC Bulletin
Board.

            (d)     Manipulation of Price. The Company has not, and to its
knowledge no one acting on its behalf has, (i) taken, directly or indirectly,
any action designed to cause or to result in the stabilization or manipulation
of the price of any security of the Company to facilitate the sale or resale of
any of the Securities or (ii) sold, bid for, purchased, or, paid any
compensation for soliciting purchases of, any of the Securities.

            (e)     Investment Company Act. The Company is not, and is not an
Affiliate (as defined below) of, and immediately after receipt of payment for
the Securities, will not be or be an Affiliate of, an "investment company"
within the meaning of the Investment Company Act of 1940, as amended.
"Affiliate" means any person or entity that, directly or indirectly through one
or more intermediaries, controls or is controlled by or is under common control
with a person or entity, as such terms are used in and construed under Rule 144
under the Securities Act.

            (f)     Registration Rights. Except as set forth in the SEC Reports
and as provided in this Agreement, no person or entity has any right to cause
the Company to effect the registration under the Securities Act of any
securities of the Company.

            (g)     No Integrated Offering. Assuming the accuracy of the
Investor's representations and warranties set forth in Section 3, neither the
Company, nor any of its Affiliates, nor, to the Company's knowledge, any person
or entity acting on its or their behalf has, directly or indirectly, made any
offers or sales of any security or solicited any offers to buy any security,
under circumstances that would cause this offering of the Securities to be
integrated with prior offerings by the Company for purposes of the Securities
Act or any applicable stockholder approval provisions.

            (h)     No General Solicitation. Neither the Company nor any person
acting on behalf of the Company has offered or sold any of the Securities by any
form of general solicitation or general advertising. The Company has offered the
Securities for sale only to the Investor and certain other "accredited
investors" within the meaning of Rule 501 under the Securities Act.

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<PAGE>
     2.6    No Conflicts. The execution, delivery and performance of this
Agreement and the Debenture by the Company and the consummation by the Company
of the transactions contemplated hereby and thereby do not and will not:
(a) conflict with or violate any provision of the Company's or any Subsidiary's
certificate or articles of incorporation, bylaws or other organizational or
charter documents, (b) conflict with, or constitute a default (or an event that
with notice or lapse of time or both would become a default) under, result in
the creation of any Lien upon any of the properties or assets of the Company or
any Subsidiary, or give to others any rights of termination, amendment,
acceleration or cancellation (with or without notice, lapse of time or both) of,
any agreement, credit facility, debt or other instrument (evidencing a Company
or Subsidiary debt or otherwise) or other understanding to which the Company or
any Subsidiary is a party or by which any property or asset of the Company or
any Subsidiary is bound or affected or (c) subject to Section 2.7, conflict with
or result in a violation of any law, rule, regulation, order, judgment,
injunction, decree or other restriction of any court or governmental authority
to which the Company or a Subsidiary is subject (including federal and state
securities laws and regulations), or by which any property or asset of the
Company or a Subsidiary is bound or affected, except to the extent that such
conflict or violation described in clauses (a)-(c) could not reasonably be
expected to result in a Material Adverse Effect.

     2.7    Governmental Consents. No consent, approval, order or authorization
of, or registration, qualification, designation, declaration or filing with, any
federal, state or local governmental authority is required on the part of the
Company in order to enable the Company to execute, deliver and perform its
obligations under this Agreement and the Debenture except for such
qualifications or filings under applicable securities laws as may be required in
connection with the transactions contemplated by this Agreement. All such
filings will be made within the time prescribed by law.

     2.8    SEC Reports; Financial Statements. The Company has filed all
reports, schedules, forms, statements and other documents required to be filed
by it under the Securities Act and the Exchange Act, including pursuant to
Section 13(a) or 15(d) of the Exchange Act (the foregoing materials
collectively, the "SEC Reports"), for the two (2) years preceding the date of
this Agreement, or such shorter period as the Company was required by law to
file such material. As of their respective dates (or, in the case of any
amendment to an SEC Report, the date of the most recent amendment), the SEC
Reports complied in all material respects with the requirements of the
Securities Act and the Exchange Act and the rules and regulations promulgated
thereunder, and none of the SEC Reports, when filed, contained any untrue
statement of a material fact or omitted to state a material fact required to be
stated therein or necessary in order to make the statements therein, in the
light of the circumstances under which they were made, not misleading. The
financial statements of the Company included in the SEC Reports comply in all
material respects with applicable accounting requirements and the rules and
regulations of the SEC with respect thereto as in effect at the time of filing.
Such financial statements have been prepared in accordance with United States
generally accepted accounting principles applied on a consistent basis during
the periods involved ("GAAP"), except as may be otherwise specified in such
financial statements or the notes thereto, and except that unaudited financial
statements may not contain all footnotes required by GAAP, and fairly present in
all material respects the financial position of the Company and its consolidated
Subsidiaries as of and for the dates thereof and the results of operations and
cash flows for the periods then ended, subject, in the case of unaudited
statements, to normal, immaterial, year-end audit adjustments.

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<PAGE>
References to the SEC Reports in this Section 2.8 shall be to the SEC Reports
filed by the Company during the two (2) years preceding the date of this
Agreement.

     2.9    Material Changes. Since the date of the latest audited financial
statements included within the SEC Reports, except as specifically disclosed in
the SEC Reports, (a) there has been no event, occurrence or development that has
had or that could reasonably be expected to result in a Material Adverse Effect,
(b) the Company has not incurred any liabilities (contingent or otherwise) other
than (i) trade payables and accrued expenses incurred in the ordinary course of
business consistent with past practice and (ii) liabilities not required to be
reflected in the Company's financial statements pursuant to GAAP or required to
be disclosed in filings made with the SEC, (c) the Company has not altered its
method of accounting, (d) the Company has not declared or made any dividend or
distribution of cash or other property to its stockholders or purchased,
redeemed or made any agreements to purchase or redeem any shares of its capital
stock and (e) the Company has not issued any equity securities to any officer,
director or Affiliate, except pursuant to the Company's 2005 Stock Incentive
Plan. The Company does not have pending before the SEC any request for
confidential treatment of information. No event, liability or development has
occurred or exists with respect to the Company or its Subsidiaries or their
respective business, properties, operations or financial condition, that would
be required to be disclosed by the Company under applicable securities laws at
the time this representation is made that has not been publicly disclosed.

     2.10   Seniority of Debenture. As of the Closing Date, other than the two
8% convertible debentures due December 7, 2009 with a conversion price of $0.40
per share held by Midsummer Investment Ltd. and Islandia, LP (the "Existing
Debenture Holders"), in an aggregate principal amount of $7,000,000.00 (the
"Existing Debentures"), no indebtedness or other equity of the Company is senior
to the Debenture in right of payment, whether with respect to interest or upon
liquidation or dissolution, or otherwise, other than indebtedness secured by
purchase money security interests (which is senior only as to underlying assets
covered thereby) and capital lease obligations (which is senior only as to the
property covered thereby).

     2.11   Litigation. There is no action, suit, inquiry, notice of violation,
proceeding or investigation pending or, to the knowledge of the Company,
threatened against or affecting the Company, any Subsidiary or any of their
respective properties before or by any court, arbitrator, governmental or
administrative agency or regulatory authority (federal, state, county, local or
foreign) (collectively, an "Action") which (a) adversely affects or challenges
the legality, validity or enforceability of any of this Agreement or the
Securities or (b) could, if there were an unfavorable decision, reasonably be
expected to result in a Material Adverse Effect. Neither the Company nor any
Subsidiary, nor, to the knowledge of the Company, any director or officer
thereof, is or has been the subject of any Action involving a claim of violation
of or liability under federal or state securities laws or a claim of breach of
fiduciary duty. There has not been, and to the knowledge of the Company, there
is not pending or contemplated, any investigation by the SEC involving the
Company or any current or former director or officer of the Company. The SEC has
not issued any stop order or other order suspending the effectiveness of any
registration statement filed by the Company under the Exchange Act or the
Securities Act.

     2.12   Labor Relations; Employees. The Company is not bound by or subject
to any collective bargaining agreement, contract, commitment or arrangement with
any labor union, and

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to the Company's knowledge, no labor union has requested, sought or attempted to
represent any employees, representatives or agents of the Company. No material
labor dispute exists or, to the knowledge of the Company, is imminent with
respect to any of the employees of the Company which could reasonably be
expected to result in a Material Adverse Effect. The Company and its
Subsidiaries are material compliance with all U.S. federal, state and local laws
and regulations relating to employment and employment practices, terms and
conditions of employment and wages and hours, except where the failure to be in
compliance could not, individually or in the aggregate, reasonably be expected
to have a Material Adverse Effect.

     2.13   Compliance. Neither the Company nor any Subsidiary (a) is in default
under or in violation of (and no event has occurred that has not been waived
that, with notice or lapse of time or both, would result in a default by the
Company or any Subsidiary under), nor has the Company or any Subsidiary received
notice of a claim that it is in default under or that it is in violation of, any
indenture, loan or credit agreement or any other material agreement or
instrument to which it is a party or by which it or any of its properties is
bound (whether or not such default or violation has been waived), (b) is in
violation of any order of any court, arbitrator or governmental body, or (c) is
in violation of any statute, rule or regulation of any governmental authority,
including without limitation all foreign, federal, state and local laws
applicable to its business, except in each of (a)-(c) as could not be reasonably
expected to have a Material Adverse Effect.

     2.14   Regulatory Permits. The Company and the Subsidiaries possess all
certificates, authorizations and permits issued by the appropriate federal,
state, local or foreign regulatory authorities necessary to conduct their
respective businesses as presently conducted, except where the failure to
possess such permits could not reasonably be expected to result in a Material
Adverse Effect ("Material Permits"), and neither the Company nor any Subsidiary
has received any notice of proceedings relating to the revocation or
modification of any Material Permit.

     2.15   Title to Assets; Leases. The Company and the Subsidiaries have good
and marketable title to all real and personal property owned by them that is
material to the business of the Company and the Subsidiaries as presently
conducted, in each case free and clear of all Liens, except for (a) Liens as do
not materially affect the value of such property and do not materially interfere
with the use made and proposed to be made of such property by the Company and
the Subsidiaries and (b) Liens for the payment of federal, state or other taxes,
the payment of which is neither delinquent nor subject to penalties. Any real
property and facilities held under lease by the Company and the Subsidiaries are
held by them under leases that are in full force and effect of which the Company
and the Subsidiaries are in material compliance.

     2.16   Intellectual Property. The Company and the Subsidiaries have, or
have rights to use, all patents, patent applications, trademarks, trademark
applications, service marks, trade names, trade secrets, inventions, copyrights,
licenses and other intellectual property rights similar rights necessary or
material for use in connection with their respective businesses as presently
conducted, except where the failure to do so could not reasonably be expected
have a Material Adverse Effect (collectively, the "Intellectual Property").
Neither the Company nor any Subsidiary has received a notice (written or
otherwise) that the material Intellectual Property used by the Company or any
Subsidiary violates or infringes upon the rights of any person or entity. To the
knowledge of the Company, all such Intellectual Property is enforceable and
there

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is no existing infringement by another person or entity of any of the material
Intellectual Property. The Company and its Subsidiaries have taken reasonable
security measures to protect the secrecy, confidentiality and value of all of
their intellectual properties, except where failure to do so could not,
individually or in the aggregate, reasonably be expect to have a Material
Adverse Effect.

     2.17   Insurance. The Company and the Subsidiaries are insured against such
losses and risks and in such amounts as are customary in the businesses in which
the Company and the Subsidiaries are engaged, including, but not limited to,
directors and officers insurance coverage.

     2.18   Transactions With Affiliates and Employees. Except as set forth in
the SEC Reports, none of the officers or directors of the Company is presently a
party to any transaction with the Company or any Subsidiary (other than for
services as employees, officers and directors), including any contract,
agreement or other arrangement providing for the furnishing of services to or
by, providing for rental of real or personal property to or from, or otherwise
requiring payments to or from any officer or director or, to the knowledge of
the Company, any entity in which any officer or director has a substantial
interest or is an officer, director, trustee or partner, in each case in excess
of $120,000 other than (a) for payment of salary or consulting fees for services
rendered, (b) reimbursement for expenses incurred on behalf of the Company and
(c) for other employee benefits, including stock option agreements under any
stock option plan of the Company.

     2.19   Taxes. Except for matters that could not, individually or in the
aggregate, reasonably be expected to result in a Material Adverse Effect, the
Company and each Subsidiary has filed all necessary federal, state and foreign
income and franchise tax returns and has paid or accrued all taxes shown as due
thereon, and the Company has no knowledge of a tax deficiency which has been
asserted or threatened against the Company or any Subsidiary.

     2.20   Certain Fees. No brokerage or finder's fees or commissions are or
will be payable by or on behalf of the Company to any broker, financial advisor
or consultant, finder, placement agent, investment banker, bank or other person
or entity with respect to the transactions contemplated by this Agreement and
the Debenture. The Investor shall have no obligation with respect to any fees or
with respect to any claims made by or on behalf of other persons or entities for
fees of a type contemplated in this Section that may be due in connection with
the transactions contemplated by this Agreement and the Debenture as a result of
actions taken by the Company.

     2.21   Disclaimer. EXCEPT AS EXPRESSLY CONTAINED IN THIS AGREEMENT, THE
COMPANY MAKES NO REPRESENTATIONS OR WARRANTIES WHATSOEVER, INCLUDING BUT NOT
LIMITED TO REPRESENTATIONS AND WARRANTIES REGARDING THE COMPANY OR THE
SECURITIES, AND HEREBY EXPRESSLY DISCLAIMS ALL OTHER WARRANTIES.

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                                   SECTION 3.
        REPRESENTATIONS and WARRANTIES; CERTAIN COVENANTS OF THE INVESTOR

     The Investor hereby represents and warrants to the Company, as of the
Closing Date, as follows:

     3.1    Organization; Good Standing; Corporate Power. The Investor has been
duly incorporated or otherwise organized, and is validly existing in good
standing, under the laws of its jurisdiction of incorporation or organization.
The Investor has the requisite corporate or organizational power and authority
to own and operate its properties and assets and to carry on its business as
currently conducted.

     3.2    Due Authorization; Enforceability. The Investor has the requisite
corporate power and authority to enter into and to consummate the transactions
contemplated by this Agreement and to carry out its obligations hereunder and
thereunder. The execution and delivery of this Agreement by the Investor and the
consummation by it of the transactions contemplated hereby have been duly
authorized by all necessary action on the part of the Investor and no further
action is required by the Investor, its board of directors or its equity holders
in connection therewith. This Agreement has been (or upon delivery will have
been) duly executed by the Investor and, when delivered in accordance with the
terms hereof and thereof and assuming due authorization and execution by the
Company, will constitute the valid and binding obligation of the Investor
enforceable against the Investor in accordance with its terms except (a) as
limited by applicable bankruptcy, insolvency, reorganization, moratorium and
other laws of general application affecting enforcement of creditors' rights
generally, (b) as limited by laws relating to the availability of specific
performance, injunctive relief or other equitable remedies and (c) insofar as
indemnification and contribution provisions may be limited by applicable law.

     3.3    Purchase for Own Account. The Investor understands that the
Securities are "restricted securities" under the Securities Act and have not
been registered under the Securities Act or any applicable state securities law
and that the Securities may be resold without registration under the Securities
Act only in certain limited circumstances. The Investor is acquiring the
Securities as principal for its own account, not as a nominee or agent, and not
with a view to or present intention of public resale or distribution of the
Securities or any part thereof with the meaning of the Securities Act, and the
Investor has no present intention of selling, granting any participation in, or
otherwise distributing the Securities. The Investor does not have any agreement
or understanding, directly or indirectly, with any person or entity to
distribute any of the Securities. The Investor is acquiring the Securities
hereunder in the ordinary course of its business, and the Investor has not been
formed for the specific purpose of acquiring the Securities. The Investor
understands that no public market now exists for any of the Securities and that
it is uncertain whether a public market will ever exist for the Securities.

     3.4    Investor Status. At the time the Investor was offered the
Securities, it was, and at the date hereof it is, and on any date on which it
converts the Debenture it will be, either: (a) an "accredited investor" as
defined in Rule 501(a) under the Securities Act or (b) a "qualified
institutional buyer" as defined in Rule 144A(a) under the Securities Act. The
Investor is not required to be registered as a broker-dealer under Section 15 of
the Exchange Act.

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<PAGE>
     3.5    Investment Experience. The Investor understands that the purchase of
the Securities involves substantial risk. The Investor has experience as an
investor in securities of companies in the development stage and acknowledges
that the Investor is able to fend for itself, can bear the economic risk of the
Investor's investment in the Securities and, at the present time, is able to
afford a complete loss of such investment. The Investor has such knowledge and
experience in financial or business matters that the Investor is capable of
evaluating the merits and risks of this investment in the Securities, and has so
evaluated the merits and risks of such investment, and is capable of protecting
its own interests in connection with this investment. The Investor represents
that the office in which its investment decision was made is located in
Malaysia.

     3.6    General Solicitation. The Investor is not purchasing the Securities
as a result of any advertisement, article, notice or other communication
regarding the Securities published in any newspaper, magazine or similar media
or broadcast over television or radio or presented at any seminar or any other
general solicitation or general advertisement. At no time was the Investor
presented with or solicited by any publicly issued or circulated newspaper,
mail, radio, television or other form of general advertising or solicitation in
connection with the offer, sale and purchase of the Securities. The Investor has
received or has had full access to all the information it considers necessary or
appropriate to make an informed investment decision with respect to the
Securities to be purchased by the Investor under this Agreement.

     3.7    Limitations on Disposition. Without in any way limiting the
representations set forth above, the Investor agrees not to make any disposition
of all or any portion of the Securities unless and until:

            (a)     there is then in effect a registration statement under the
Securities Act covering such proposed disposition and such disposition is made
in accordance with such registration statement; or

            (b)     the Investor shall have notified the Company of the proposed
disposition and shall have furnished the Company with a statement of the
circumstances surrounding the proposed disposition, and, if requested by the
Company, at the expense of the Investor or its transferee, with an opinion of
counsel, reasonably satisfactory to the Company, that such disposition will not
require registration of such securities under the Securities Act.

     Notwithstanding the provisions of paragraphs (a) and (b) above, no such
registration statement or opinion of counsel shall be required for any transfer
of any Securities in compliance with Securities Act Rule 144 or Rule 144A.

     3.8    Non-U.S. Investor. The Investor hereby represents that it has
satisfied itself as to the full observance of the laws of its jurisdiction in
connection with the acquisition of the Securities, including (a) the legal
requirements within its jurisdiction for the acquisition of the Securities, (b)
any foreign exchange restrictions applicable to such acquisition, (c) any
governmental or other consents that may need to be obtained, and (d) the income
tax and other tax consequences, if any, that may be relevant to the purchase,
holding, redemption, sale or other transfer of the Securities. The Investor's
acquisition of and continued beneficial or legal

                                      -10-
<PAGE>
ownership of the Securities, will not violate any applicable securities or other
laws of its jurisdiction.

     3.9    Legend. It is understood that the certificates evidencing the
Securities will bear the legend set forth below:

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), WITH THE UNITED STATES SECURITIES AND
EXCHANGE COMMISSION OR UNDER THE SECURITIES LAWS OF ANY OTHER JURISDICTIONS.
THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE
APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN
FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED
TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE
SECURITIES LAWS.

     The Company shall remove or cause to be removed the legend set forth above
from any certificate evidencing the Securities upon delivery to the Company of
an opinion by counsel, reasonably satisfactory to the Company, that a
registration statement under the Securities Act is at that time in effect with
respect to the legended security or that such security can be freely transferred
in a public sale without such a registration statement being in effect and that
such transfer will not jeopardize the exemption or exemptions from registration
pursuant to which the Company issued the Securities.

     3.10   Confidentiality. Other than the transaction contemplated under this
Agreement, the Investor has not directly or indirectly, nor has any person or
entity acting on behalf of or pursuant to any understanding with the Investor,
executed any transaction in the securities or derivative securities of the
Company during the period commencing from the time that the Investor first
received a term sheet from the Company or any other person or entity setting
forth the material terms of the transactions contemplated hereunder until the
date hereof. The Investor has maintained the confidentiality of all disclosures
made to it in connection with this transaction (including the existence and
terms of this transaction).

     3.11   U.S. Patriot Act.

            (a)     The Investor maintains a place of business that is located
at a fixed address (other than an electronic address or post office box).

            (b)     The Purchase Price will not directly or indirectly be
derived from activities that may contravene federal, state, foreign and
international laws and regulations, including anti-money laundering laws, and
acknowledges the federal regulations and Executive Orders administered by the
United States Department of Treasury's Office of Foreign Assets Control
("OFAC").

                                      -11-
<PAGE>
            (c)     Neither the Investor nor any of its subsidiaries, and, to
its knowledge, none of its officers, directors or affiliated entities, appear on
any of the following lists maintained by the United States government
("Government Lists"), and the Investor does not transact business on behalf of,
or for the direct or indirect benefit of, any individual or entity named on any
Government List: (i) the Denied Persons and Entities Lists maintained by the
U.S. Commerce Department; (ii) the Specially Designated Nationals and Blocked
Persons Lists maintained by the U.S. Treasury Department; (iii) the Terrorist
Organizations and Debarred Parties Lists maintained by the U.S. State
Department; or (iv) any other list of terrorists, terrorist organizations or
narcotics traffickers maintained pursuant to any of the rules and regulations of
OFAC, the U.S. Treasury Department, or by any other government agency.

            (d)     The undersigned, and, to its knowledge, each of its officers
or directors, is not a senior foreign political figure, or an immediate family
member or close associate of a senior foreign political figure within the
meaning of the USA PATRIOT Act of 2001.

     3.12   Certain Fees. No brokerage or finder's fees or commissions are or
will be payable by or on behalf of the Investor to any broker, financial advisor
or consultant, finder, placement agent, investment banker, bank or other person
or entity with respect to the transactions contemplated by this Agreement and
the Debenture. The Company shall have no obligation with respect to any fees or
with respect to any claims made by or on behalf of other persons or entities for
fees of a type contemplated in this Section that may be due in connection with
the transactions contemplated by this Agreement and the Debenture as a result of
actions taken by or on behalf of the Investor.

     3.13   Disclaimer. EXCEPT AS EXPRESSLY CONTAINED IN THIS AGREEMENT, THE
INVESTOR MAKES NO REPRESENTATIONS OR WARRANTIES WHATSOEVER AND HEREBY EXPRESSLY
DISCLAIMS ALL OTHER WARRANTIES.

                                   SECTION 4.
                                   COVENANTS

     4.1    Registration of the Shares.

            (a)     Registration. Upon request by the Investor, the Company
shall use its commercially reasonable efforts to register the resale by the
Investor of all, or that portion requested by the Investor (so long as such
portion does not represent less than 33 1/3% of the Purchase Shares and
Debenture Shares acquired on the Closing Date), of the Purchase Shares and the
Debenture Shares under the Securities Act. The Investor acknowledges and agrees
that, depending on the status of the Investor at the time of registration, such
resale registration may not be for an offering to be made on a continuous basis
pursuant to Securities Act Rule 415. The Company shall use its commercially
reasonable efforts to (i) cause to be declared effective or become effective
under the Securities Act a registration statement filed pursuant to this Section
4.1(a) within one (1) year from the initial date of filing of such registration
statement and (ii) avoid the issuance of or, if issued, obtain the withdrawal of
any order suspending the effectiveness of a registration statement filed
pursuant to this Section. The Company's obligations under this Section 4.1(a)
shall terminate on the earlier of (A) two (2) years from the

                                      -12-
<PAGE>
Closing Date and (B) the date upon which the Investor may sell the Purchase
Shares and the Debenture Shares pursuant to Securities Act Rule 144(k).

            (b)     Expenses. All fees and expenses incurred in connection with
or incident to registration of the Purchase Shares and the Debenture Shares
pursuant to this Section 4.1 shall be borne by the Company. The Investor shall
pay all commissions and discounts arising from the sale of any Purchase Shares
and/or Debenture Shares.

            (c)     Indemnification by the Company. Upon the registration of any
of the Purchase Shares or the Debenture Shares the Company shall, and it hereby
agrees to, (i) indemnify and hold harmless the Investor against any losses,
claims, damages or liabilities ("Losses") to which the Investor may become
subject, under the Securities Act or otherwise, insofar as such Losses (or
actions in respect thereof) arise out of or are based upon an Untrue Statement
(as defined below) and (ii) reimburse the Investor for any legal or other
expenses reasonably incurred by the Investor in connection with investigating or
defending any such action or claim; provided, however, that the Company shall
not be liable to the Investor in any such case to the extent that any such Loss
arises out of or is based upon an Untrue Statement in reliance upon and in
conformity with information furnished to the Company by the Investor expressly
for use in the registration statement, prospectus, amendment or supplement in
which the Untrue Statement is contained; provided, further, that the Company
shall not be liable to the Investor under the indemnity agreement in this
Section 4.1(c) with respect to (A) any preliminary prospectus to the extent that
any such Loss of the Investor which results from the fact that the Investor sold
Purchase Shares or Debenture Shares to a person to whom there was not sent or
given, at or prior to the written confirmation of such sale, a copy of the
related final prospectus if the Company has previously furnished such prospectus
on a timely basis to the Investor and such prospectus corrects the Untrue
Statement out of which such Loss arises or (B) any preliminary or final
prospectus to the extent that any such Loss of the Investor arises from the fact
that the Investor delivered such preliminary or final prospectus after receipt
of any notice from the Company that the prospectus is outdated or defective and
such prospectus contains the Untrue Statement out of which such Loss arises.
"Untrue Statement" means any untrue statement or alleged untrue statement of a
material fact contained in any registration statement under which the Purchase
Shares and/or the Debenture Shares are registered under the Securities Act, or
any preliminary or final prospectus contained therein, or in any amendment or
supplement thereto, or omission or alleged omission to state therein a material
fact required to be stated therein or necessary to make the statements therein
not misleading (in the case of the registration statement or any amendment
thereto) or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading (in the case of any
preliminary or final prospectus or supplement thereto).

            (d)     Indemnification by the Investor. Upon the registration of
any of the Purchase Shares or the Debenture Shares the Investor shall, and it
hereby agrees to, (i) indemnify and hold harmless the Company against any Losses
to which the Company may become subject, under the Securities Act or otherwise,
insofar as such Losses (or actions in respect thereof) arise out of or are based
upon (A) an Untrue Statement to the extent, but only to the extent, that such
Untrue Statement was made in reliance upon and in conformity with information
furnished to the Company by the Investor expressly for use in the registration
statement, prospectus, amendment or supplement in which the Untrue Statement is
contained or (B) circumstances described in

                                      -13-
<PAGE>
Section 4.1(c)(A) or (B), and (ii) reimburse the Company for any legal or other
expenses reasonably incurred by the Company in connection with investigating or
defending any such action or claim; provided, however, that the Investor shall
not be required to undertake liability under this Section 4.1(d) for any amounts
in excess of the dollar amount of the net proceeds to be received by the
Investor from the sale of the Purchase Shares and/or Debenture Shares registered
pursuant to such registration.

     4.2    Directors. The Company shall use its commercially reasonable efforts
to cause director candidates recommended by the Investor to be nominated and
elected to the board of directors of the Company, in proportion to the
Investor's ownership.

     4.3    Extinguishment of the Existing Debentures. In order to extinguish
the Existing Debentures, the Company shall use (a) $3,500,000.00 of the net
proceeds from the sale of the Securities hereunder for payment of principal on
the Existing Debentures and (b) Common Stock to convert the remaining
outstanding principal and interest on the Existing Debentures at a conversion
rate of $0.35 per share, pursuant to the Conversion and Termination between the
Company and the Existing Debenture Holders dated as of February 26, 2008.

     4.4    Affiliate. The Investor acknowledges and agrees that immediately
following the consummation of the transactions contemplated by this Agreement,
the Investor will be an "affiliate" of the Company for purposes of the
Securities Act and the Exchange Act.

     4.5    Schedule 13D or 13G. The Investor acknowledges and agrees that it
will be required under Section 13(d) or (g) of the Exchange Act to file a
Schedule 13D or 13G with the SEC, as applicable, following the Closing.

     4.6    Form 3. The Investor acknowledges and agrees that following the
Closing, the Investor will be required to make filings with the SEC pursuant to
Section 16 of the Exchange Act, including but not limited to a Form 3.

     4.7    Withholding Tax. The Investor acknowledges and agrees that the
Company may be required by applicable tax law to withhold certain amounts
payable on the Debenture, and that any payments to the Investor thereunder will
be net of such withheld amounts. The Company agrees that it will pay all such
withheld amounts to the applicable taxing authority in the manner and within the
time period required by applicable law.

                                   SECTION 5.
                               GENERAL PROVISIONS

     5.1    Survival. The representations and warranties of the parties hereto
shall not survive the Closing, except for those (a) regarding the corporate
power and authority and due authorization of each of the parties to enter into
and perform its obligations under this Agreement, and due execution and
enforceability of this Agreement by and against such party, (b) of the Investor
upon which the Company has relied and will rely for the issuance of the
Securities to the Investor without registration under the Securities Act and (c)
contained in Sections 2.20 and 3.12. The covenants and other agreements of the
parties contained herein shall survive the Closing for the applicable statute of
limitations.

                                      -14-
<PAGE>
     5.2    Successors and Assigns. Neither party may assign its rights or
obligations under this Agreement. This Agreement, and the rights and obligations
of the parties hereunder, will be binding upon and inure to the benefit of their
respective successors and assigns.

     5.3    Governing Law. This Agreement will be governed by and construed in
accordance with the laws of the State of California, without giving effect to
that body of laws pertaining to conflict of laws.

     5.4    Counterparts. This Agreement may be executed in any number of
counterparts, each of which when so executed and delivered will be deemed an
original, and all of which together shall constitute one and the same agreement.

     5.5    Facsimile Signatures. This Agreement may be executed and delivered
by facsimile and upon such delivery the facsimile signature will be deemed to
have the same effect as if the original signature had been delivered to the
other party.

     5.6    Titles and Headings. The titles, captions and headings of this
Agreement are included for ease of reference only and will be disregarded in
interpreting or construing this Agreement. Unless otherwise specifically stated,
all references herein to "sections" and "exhibits" will mean "sections" and
"exhibits" to this Agreement.

     5.7    Notices. Any and all notices required or permitted to be given to a
party pursuant to the provisions of this Agreement will be in writing and will
be effective and deemed to provide such party sufficient notice under this
Agreement on the earliest of the following: (a) at the time of personal
delivery, if delivery is in person; (b) at the time of transmission by
facsimile, addressed to the other party at its facsimile number specified herein
(or hereafter modified by subsequent notice to the parties hereto), with
confirmation of receipt made by printed confirmation sheet verifying successful
transmission of the facsimile; (c) the day of sending such notice by electronic
mail with a read or delivered receipt; (d) one (1) business day after deposit
with an express overnight courier for United States deliveries, or two (2)
business days after such deposit for deliveries outside of the United States,
with proof of delivery from the courier requested; or (e) three (3) business
days after deposit in the United States mail by certified mail (return receipt
requested) for United States deliveries.

     All notices for delivery outside the United States will be sent by
facsimile or by express courier. Notices by facsimile shall be machine verified
as received. All notices not delivered personally or by facsimile will be sent
with postage and/or other charges prepaid and properly addressed to the party to
be notified at the address or facsimile number as follows, or at such other
address or facsimile number as such other party may designate by one of the
indicated means of notice herein to the other parties hereto as follows:

     if to the Investor, to:

            Halfmoon Bay Capital Ltd
            Trident Chambers
            P.O. Box 146
            Road Town Tortola
            British Virgin Islands

                                      -15-
<PAGE>
            Facsimile:    603-2163-3552
            Attention:    Wan Azmi Wan Hamzah

     if to the Company, to:

            Electronic Sensor Technology, Inc.
            1077 Business Center Circle
            Newbury Park, California 91320
            Facsimile:    805-480-1984
            Attention:    President and Chief Executive Officer

     5.8    Costs and Expenses. The Company and the Investor shall each bear
their own respective costs and expenses, including but not limited to
professional costs and fees, incurred in connection with the negotiation and
consummation of this Agreement and the Debenture.

     5.9    Amendments; Waivers. No provision of this Agreement may be waived,
modified, supplemented or amended except in a written instrument signed, in the
case of an amendment, by the Company and the Investor or, in the case of a
waiver, by the party against whom enforcement of any such waiver is sought. No
waiver of any default with respect to any provision, condition or requirement of
this Agreement shall be deemed to be a continuing waiver in the future or a
waiver of any subsequent default or a waiver of any other provision, condition
or requirement hereof, nor shall any delay or omission of either party to
exercise any right hereunder in any manner impair the exercise of any such
right.

     5.10   Entire Agreement. This Agreement and the Debenture, together with
the exhibits and schedules thereto, contain the entire understanding of the
parties with respect to the subject matter hereof and supersede all prior
agreements and understandings, oral or written, with respect to such matters,
which the parties acknowledge have been merged into such documents, exhibits and
schedules.

     5.11   Severability. If any provision of this Agreement is held to be
invalid or unenforceable in any respect, the validity and enforceability of the
remaining terms and provisions of this Agreement shall not in any way be
affected or impaired thereby and the parties will attempt to agree upon a valid
and enforceable provision that is a reasonable substitute therefor, and upon so
agreeing, shall incorporate such substitute provision in this Agreement.

     5.12   Further Assurances. The parties agree to execute such further
documents and instruments and to take such further actions as may be reasonably
necessary to carry out the purposes and intent of this Agreement.

     5.13   No Third-Party Beneficiaries. This Agreement is intended for the
benefit of the parties hereto and their respective successors and permitted
assigns and is not for the benefit of, nor may any provision hereof be enforced
by, any other person or entity.

     5.14   Construction. The parties agree that each of them and/or their
respective counsel has reviewed and had an opportunity to revise this Agreement
and the Debenture and, therefore, the normal rule of construction to the effect
that any ambiguities are to be resolved against the

                                      -16-
<PAGE>
drafting party shall not be employed in the interpretation of the this Agreement
and any amendments hereto.

                               *        *        *

                                      -17-
<PAGE>
     IN WITNESS WHEREOF, each of the parties hereto has caused its name to be
hereunto subscribed by its duly authorized signatory as of the day and year
first above written.

                                    ELECTRONIC SENSOR TECHNOLOGY, INC.

                                    By: /s/ Barry S. Howe
                                        ----------------------------------------
                                    Name:  Barry S. Howe
                                    Title: President and Chief Executive Officer

                                    HALFMOON BAY CAPITAL LTD

                                    By: /s/ Wan Azmi Wan Hamzah
                                        ----------------------------------------
                                    Name:  Wan Azmi Wan Hamzah
                                    Title: Authorized Signatory

                                -Signature Page-
                               Securities Purchase
                                    Agreement
<PAGE>
                                    Exhibit A

                                FORM OF DEBENTURE

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), WITH THE UNITED STATES SECURITIES AND
EXCHANGE COMMISSION OR UNDER THE SECURITIES LAWS OF ANY OTHER JURISDICTIONS.
THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE
APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN
FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED
TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE
SECURITIES LAWS.

                       ELECTRONIC SENSOR TECHNOLOGY, INC.
                             (a Nevada corporation)

                            9% CONVERTIBLE DEBENTURE

Issue Date: March 28, 2008                                         $2,000,000.00
Maturity Date: March 28, 2013
Conversion Price: $0.0486

     This 9% CONVERTIBLE DEBENTURE (this "Debenture") is issued by ELECTRONIC
SENSOR TECHNOLOGY, INC., a Nevada corporation (the "Company"). FOR VALUE
RECEIVED, the Company promises to pay to HALFMOON BAY CAPITAL LTD, a British
Virgin Islands company (together with its registered successors and assigns, the
"Holder"), the principal sum of $2,000,000.00 on or before the Maturity Date,
together with interest on the aggregate unconverted principal amount, in the
amounts and at the times set forth below.

1.   Interest; Redemption.

     (a)    Interest. Interest shall accrue on the unpaid principal balance of
this Debenture from the Issue Date to but excluding the Maturity Date at a rate
per annum of nine percent (9%), calculated on the basis of a 365/366 day year,
as the case may be, and actual days elapsed, and shall be payable in arrears on
each Interest Payment Date (as defined below) for the period commencing on the
immediately preceding Interest Payment Date (or, in the case of the first
Interest Payment Date, commencing on the Issue Date) and ending on the calendar
day immediately preceding such Interest Payment Date. As used herein, "Interest
Payment Date" means (i) March 28 and September 28 of each year; (ii) each date
of prepayment, in respect of the principal amount of this Debenture that is
being prepaid; (iii) each Conversion Date (as

                                       A-1
<PAGE>
defined in Section 2(a)), in respect of the principal amount of this Debenture
that is being converted; and (iv) the date on which the principal amount of this
Debenture is due in full (whether at maturity, by acceleration or otherwise).

     (b)    Principal. The unconverted unpaid principal amount of this Debenture
shall be due and payable on the Maturity Date.

     (c)    Payments. Principal and interest on this Debenture less any amounts
required to be withheld by any tax authority with jurisdiction over the Company
(the "Withheld Amounts") shall be paid to the Holder in United States Dollars by
wire transfer of immediately available funds to such account located within the
continental United States of America as the Holder may notify the Company in
writing from time to time. The Company shall pay all Withheld Amounts to the
applicable taxing authority in the manner and within the time period required by
applicable law.

     (d)    Prepayment. In the event that the Company intends to prepay all or
any portion of the principal amount of this Debenture, it shall notify the
Holder in writing of its intention to do so, specifying the principal amount
that the Company intends to prepay (a "Repayment Notice"). Upon the Holder's
receipt of a Repayment Notice, the Holder may exercise its right to convert all
or any portion of the principal amount of this Debenture pursuant to Section
2(a) by delivering a Notice of Conversion (as defined in Section 2(a)) within
fifteen (15) days of receipt of the Repayment Notice (the "Conversion Window
Period"). If the Holder does not deliver a Notice of Conversion to the Company
during the Conversion Window Period, the Company shall pay to the Holder the
principal amount set forth in the Repayment Notice within five (5) Business Days
following the end of the Conversion Window Period.

     (e)    Business Days. Any payment that would be due on a date that is a
Saturday, Sunday or day that is a federal legal holiday in the United States or
a day on which banking institutions in the State of California are authorized or
required by law or other government action to close, shall instead be due on the
next succeeding day that does not fall into any of the foregoing categories (a
"Business Day").

2.   Conversion.

     (a)    Voluntary Conversion. At any time from the date hereof until this
Debenture is no longer outstanding, so long as the Holder is an "accredited
investor" as defined in Rule 501(a) under the Act or a "qualified institutional
buyer" as defined in Rule 144A(a) under the Act, this Debenture shall be
convertible into shares of common stock of the Company, par value $.001 per
share (the "Common Stock") at the option of the Holder, in whole or in part at
any time and from time to time. The Holder shall effect conversions by
delivering to the Company a notice of conversion in the form attached hereto as
Exhibit A (a "Notice of Conversion"), specifying therein the principal amount of
this Debenture to be converted and the date on which such conversion is to be
effected (a "Conversion Date"). If no Conversion Date is specified in a

                                       A-2
<PAGE>
Notice of Conversion, the Conversion Date shall be the date that such Notice of
Conversion is received by the Company.

     (b)    Mechanics of Conversion. The number of shares of Common Stock
issuable upon a conversion hereunder (the "Conversion Shares") shall be
equivalent to (i) the outstanding principal amount of this Debenture to be
converted as set forth in the Notice of Conversion, divided by (ii) the
Conversion Price (as adjusted pursuant to Section 3 through the Conversion
Date). As soon as practicable following the Conversion Date, the Company will
deliver or cause to be delivered to the Holder a certificate in the Holder's
name representing the Conversion Shares.

     (c)    Reservation of Shares Issuable Upon Conversion. The Company
covenants that it will at all times while this Debenture remains outstanding,
reserve and keep available out of its authorized and unissued shares of Common
Stock, shares of Common Stock solely for the purpose of issuance upon conversion
in full of this Debenture. The Company covenants that all shares of Common Stock
so issuable shall, upon issue, be duly and validly authorized, issued and fully
paid and non-assessable.

3.   Adjustment of Conversion Price.

     (a)    Stock Dividends and Stock Splits. If the Company, at any time while
this Debenture is outstanding (i) pays a stock dividend or otherwise makes a
distribution or distributions on shares of its Common Stock or any other equity
or equity equivalent securities payable in shares of Common Stock, (ii)
subdivides outstanding shares of Common Stock into a larger number of shares,
(iii) combines (including by way of reverse stock split) outstanding shares of
Common Stock into a smaller number of shares, or (iv) issues by reclassification
of shares of the Common Stock any shares of capital stock of the Company, then
the Conversion Price shall be multiplied by the quotient of (A) the number of
shares of Common Stock outstanding immediately before such event, divided by (B)
the number of shares of Common Stock outstanding immediately after such event.

     (b)    Fundamental Transaction. If, at any time while this Debenture is
outstanding, (i) the Company effects any merger or consolidation of the Company
with or into another entity, (ii) the Company effects any sale of all or
substantially all of its assets in one or a series of related transactions,
(iii) any tender offer or exchange offer (whether by the Company or another
person or entity) is completed pursuant to which holders of Common Stock are
permitted to tender or exchange their shares for other securities, cash or
property, or (iv) the Company effects any reclassification of the Common Stock
or any compulsory share exchange pursuant to which the Common Stock is
effectively converted into or exchanged for other securities, cash or property
(in any such case, a "Fundamental Transaction"), then upon any subsequent
conversion of this Debenture, the Holder shall have the right to receive, for
each Conversion Share that would have been issuable upon such conversion
immediately prior to the occurrence of such Fundamental Transaction, the same
kind and amount of securities, cash or property as it would have been

                                       A-3
<PAGE>
entitled to receive upon the occurrence of such Fundamental Transaction if it
had been, immediately prior to such Fundamental Transaction, the holder of one
share of Common Stock.

     (c)    Notice to Holder. Whenever the Conversion Price is adjusted pursuant
to this Section 3, the Company shall promptly mail to the Holder a notice
setting forth the Conversion Price after such adjustment and setting forth a
brief statement of the facts requiring such adjustment.

4.   Events of Default.

     (a)    "Event of Default", wherever used herein, means any one of the
following events:

            (i)     Any default in the payment when due and payable of
     (A) interest on this Debenture, which failure to pay is not cured within
     three (3) Business Days, or (B) principal of this Debenture;

            (ii)    A material breach by the Company of its other obligations
     under this Debenture, which material breach is not cured within thirty (30)
     days following receipt of notice thereof from the Holder; or

            (iii)   (A) The Company commences a case, as debtor, under any
     applicable bankruptcy or insolvency laws as now or hereafter in effect or
     any successor thereto, or any other proceeding under any reorganization,
     arrangement, adjustment of debt, relief of debtors, dissolution, insolvency
     or liquidation or similar law of any jurisdiction whether now or hereafter
     in effect relating to the Company; (B) there is commenced a case against
     the Company under any applicable bankruptcy or insolvency laws, as now or
     hereafter in effect or any successor thereto, which remains undismissed for
     a period of ninety (90) days; (C) the Company is adjudicated by a court of
     competent jurisdiction insolvent or bankrupt; (D) the Company suffers any
     appointment of any custodian or the like for the Company or any substantial
     part of its property, which continues undischarged or unstayed for a period
     of ninety (90) days; or (E) the Company makes a general assignment for the
     benefit of creditors.

     (b)    Remedies Upon Event of Default. If any Event of Default occurs, the
full principal amount of this Debenture, together with accrued and unpaid
interest thereon, shall become immediately due and payable in cash. Amounts not
paid when due shall bear interest at the maximum lawful rate and shall be
payable upon demand of the Holder.

5.   Miscellaneous.

     (a)    Notices. Any and all notices required or permitted to be given to a
party pursuant to the provisions of this Debenture shall be made in accordance
with Section 6.8 of the Securities

                                       A-4
<PAGE>
Purchase Agreement between the Company and the Holder dated on or about the date
hereof, which Section is incorporated herein by reference.

     (b)    Lost or Mutilated Debenture. If this Debenture shall be mutilated,
lost, stolen or destroyed, the Company shall execute and deliver, in exchange
and substitution for and upon cancellation of a mutilated Debenture, or in lieu
of or in substitution for a lost, stolen or destroyed Debenture, a new Debenture
for the principal amount of this Debenture so mutilated, lost, stolen or
destroyed but only upon receipt of evidence of such loss, theft or destruction
of such Debenture, and of the ownership hereof, and indemnity, if requested, all
reasonably satisfactory to the Company.

     (c)    Governing Law. This Debenture will be governed by and construed in
accordance with the laws of the State of California, without giving effect to
that body of laws pertaining to conflict of laws.

     (d)    Waiver. Any waiver by the Holder of a breach of any provision of
this Debenture shall not operate as or be construed to be a waiver of any other
breach of such provision or of any breach of any other provision of this
Debenture.

     (e)    Severability. If any provision of this Debenture is held to be
invalid or unenforceable in any respect, the validity and enforceability of the
remaining terms and provisions of this Debenture shall not in any way be
affected or impaired thereby and the Company and the Holder will attempt to
agree upon a valid and enforceable provision that is a reasonable substitute
therefor, and upon so agreeing, shall incorporate such substitute provision in
this Debenture.

     (f)    Headings. The headings contained herein are for convenience only, do
not constitute a part of this Debenture and shall not be deemed to limit or
affect any of the provisions hereof.

                           *            *            *

                                       A-5
<PAGE>
     IN WITNESS WHEREOF, the Company has caused this Debenture to be duly
executed by a duly authorized officer as of the date first above indicated.

                                    ELECTRONIC SENSOR TECHNOLOGY, INC.

                                    By:
                                        ----------------------------------------
                                    Name:  Barry S. Howe
                                    Title: President and Chief Executive Officer

                                       A-6
<PAGE>
                                    Exhibit A

                              NOTICE OF CONVERSION

     Halfmoon Bay Capital Ltd (the "Holder") hereby elects to convert principal
under the 9% Convertible Debenture of Electronic Sensor Technology, Inc., a
Nevada corporation, due on March 28, 2013, into shares of common stock of the
Company, par value $.001 per share (the "Common Stock"), as of the date written
below.

     Conversion Date:

     Principal Amount of Debenture to be Converted:

     Number of Shares of Common Stock to be Issued:

     The Holder hereby represents, warrants and certifies that it is (a) an
"accredited investor" as defined in Rule 501(a) under the Securities Act of
1933, as amended (the "Securities Act") or a "qualified institutional buyer" as
defined in Rule 144A(a) under the Securities Act, (b) not required to be
registered as a broker-dealer under Section 15 of the Securities Exchange Act of
1934, as amended, and (c) acquiring the Common Stock for its own account and not
with a view toward public resale or distribution.

                                    HALFMOON BAY CAPITAL LTD

                                    By:
                                        ----------------------------------------
                                    Name:
                                    Title:

                                       A-7exv4w3

 

Exhibit 4.3

 

 

ENTERPRISE PRODUCTS OPERATING LLC

AS ISSUER,

ENTERPRISE PRODUCTS PARTNERS L.P.

AS PARENT GUARANTOR,

and

WELLS FARGO BANK,

NATIONAL ASSOCIATION,

AS TRUSTEE

 

TWELFTH SUPPLEMENTAL INDENTURE

Dated as of April 3, 2008

to

Indenture dated as of October 4, 2004

 

$400,000,000

5.65% Senior Notes due 2013

 

 

 

 

TABLE OF CONTENTS

	 	 	 	 	 
	 	 	 	 	Page
	 
	 	 	 	 
	 
	 	ARTICLE I	 	 
	 
	 	 	 	 
	 
	 	THE NOTES	 	 
	 
	 	 	 	 
	SECTION 1.1
	 	Form	 	2
	SECTION 1.2
	 	Title, Amount and Payment of Principal and Interest	 	2
	SECTION 1.3
	 	Registrar and Paying Agent	 	3
	SECTION 1.4
	 	Transfer and Exchange	 	3
	SECTION 1.5
	 	Guarantee of the Notes	 	3
	SECTION 1.6
	 	Defeasance and Discharge	 	3
	SECTION 1.7
	 	Amendment to Section 4.12 of the Original Indenture	 	3
	SECTION 1.8
	 	Amendment to Section 4.13 of the Original Indenture	 	4
	 
	 	 	 	 
	 
	 	ARTICLE II	 	 
	 
	 	 	 	 
	 
	 	REDEMPTION	 	 
	 
	 	 	 	 
	SECTION 2.1
	 	Redemption	 	4
	 
	 	 	 	 
	 
	 	ARTICLE III	 	 
	 
	 	 	 	 
	 
	 	MISCELLANEOUS PROVISIONS	 	 
	 
	 	 	 	 
	SECTION 3.1
	 	Table of Contents, Headings, etc.	 	4
	SECTION 3.2
	 	Counterpart Originals	 	4
	SECTION 3.3
	 	Governing Law	 	5
	 
	 	 	 	 
	Exhibit A
	 	Form of Note	 	A-1

i

 

     THIS TWELFTH SUPPLEMENTAL INDENTURE dated as of April 3, 2008, is among Enterprise Products
Operating LLC, a Texas limited liability company (the “Issuer”), Enterprise Products Partners L.P.,
a Delaware limited partnership (the “Parent Guarantor”), and Wells Fargo Bank, National
Association, a national banking association, as trustee (the “Trustee”). Each capitalized term
used but not defined in this Twelfth Supplemental Indenture shall have the meaning assigned to such
term in the Original Indenture (as defined below).

RECITALS:

     WHEREAS, Enterprise Products Operating L.P. and the Parent Guarantor have executed and
delivered to the Trustee an Indenture, dated as of October 4, 2004 (the “Original Indenture”),
providing for the issuance by Enterprise Products Operating L.P. from time to time of its
debentures, notes, bonds or other evidences of indebtedness, issued and to be issued in one or more
series unlimited as to principal amount (the “Debt Securities”), and the guarantee by each
Guarantor of the Debt Securities (the “Guarantee”); and

     WHEREAS, the Issuer and the Parent Guarantor have executed and delivered to the Trustee a
Tenth Supplemental Indenture, dated as of June 30, 2007, providing for the Issuer as the successor
issuer (the Original Indenture together with the Tenth Supplemental Indenture, the “Base
Indenture”); and

     WHEREAS, on or before the date hereof the Issuer has issued several series of Debt Securities
pursuant to previous supplements to the Base Indenture;

     WHEREAS, the Issuer has duly authorized and desires to cause to be issued pursuant to the Base
Indenture and this Twelfth Supplemental Indenture a new series of Debt Securities designated the
“5.65% Senior Notes due 2013” (the “Notes”), all of such Notes to be guaranteed by the Parent
Guarantor as provided in Article XIV of the Original Indenture;

     WHEREAS, the Issuer desires to cause the issuance of the Notes pursuant to Sections 2.01 and
2.03 of the Original Indenture, which sections permit the execution of indentures supplemental
thereto to establish the form and terms of Debt Securities of any series;

     WHEREAS, pursuant to Section 9.01 of the Original Indenture, the Issuer and the Parent
Guarantor have requested that the Trustee join in the execution of this Twelfth Supplemental
Indenture to establish the form and terms of the Notes;

     WHEREAS, all things necessary have been done to make the Notes, when executed by the Issuer
and authenticated and delivered hereunder and under the Base Indenture and duly issued by the
Issuer, and the Guarantee of the Parent Guarantor, when the Notes are duly issued by the Issuer,
the valid obligations of the Issuer and the Parent Guarantor, respectively, and to make this
Twelfth Supplemental Indenture a valid agreement of the Issuer and the Parent Guarantor enforceable
in accordance with its terms.

     NOW, THEREFORE, the Issuer, the Parent Guarantor and the Trustee hereby agree that the
following provisions shall supplement the Base Indenture:

 

 

ARTICLE I

THE NOTES

     SECTION 1.1 Form.

     The Notes and the Trustee’s certificate of authentication shall be substantially in the form
of Exhibit A to this Twelfth Supplemental Indenture, which is hereby incorporated into this
Twelfth Supplemental Indenture. The terms and provisions contained in the Notes shall constitute,
and are hereby expressly made, a part of this Twelfth Supplemental Indenture and to the extent
applicable, the Issuer, the Parent Guarantor and the Trustee, by their execution and delivery of
this Twelfth Supplemental Indenture, expressly agree to such terms and provisions and to be bound
thereby.

     The Notes shall be issued only as Registered Securities. The Notes shall be issued upon
original issuance in whole in the form of one or more Global Securities (the “Book-Entry Notes”).
Each Book-Entry Note shall represent such of the Outstanding Notes as shall be specified therein
and shall provide that it shall represent the aggregate amount of Outstanding Notes from time to
time endorsed thereon and that the aggregate amount of Outstanding Notes represented thereby may
from time to time be reduced or increased, as appropriate, to reflect exchanges and redemptions.
Any endorsement of a Book-Entry Note to reflect the amount, or any increase or decrease in the
amount, of Outstanding Notes represented thereby shall be made by the Trustee in accordance with
written instructions or such other written form of instructions as is customary for the Depositary,
from the Depositary or its nominee on behalf of any Person having a beneficial interest in the
Book-Entry Note.

     The Issuer initially appoints The Depository Trust Company (“DTC”) to act as Depositary with
respect to the Book-Entry Notes.

     SECTION 1.2 Title, Amount and Payment of Principal and Interest.

     The Notes shall be entitled the “5.65% Senior Notes due 2013.” The Trustee shall authenticate
and deliver (i) the Notes for original issue on the date hereof (the “Original Notes”) in the
aggregate principal amount of $400 million and (ii) additional Notes for original issue from time
to time after the date hereof in such principal amounts as may be specified in the Company Order
described in this sentence, provided that no such additional Notes may be issued at a price that
would cause such Notes to have “original issue discount” within the meaning of the Internal Revenue
Code of 1986, as amended, in each case upon a Company Order for the authentication and delivery
thereof and satisfaction of the other provisions of Section 2.05 of the Original Indenture. Such
order shall specify the amount of the Notes to be authenticated, the date on which the original
issue of Notes is to be authenticated, and the name or names of the initial Holder or Holders. The
aggregate principal amount of Notes that may be outstanding at any time may not exceed $400 million
plus such additional principal amounts as may be issued and authenticated pursuant to clause (ii)
of this paragraph (except as provided in Section 2.09 of the Original Indenture).

     The principal amount of each Note shall be payable on April 1, 2013. Each Note shall bear
interest from the date of original issuance, or the most recent date to which interest has been

2

 

paid, at the fixed rate of 5.65% per annum. The dates on which interest on the Notes shall be
payable shall be April 1 and October 1 of each year, commencing October 1, 2008 in the case of the
Original Notes (the “Interest Payment Dates”). The regular record date for interest payable on the
Notes on any Interest Payment Date shall be March 15 or September 15 (the “Regular Record Date”),
as the case may be, next preceding such Interest Payment Date.

     Payments of principal of, premium, if any, and interest due on the Notes representing
Book-Entry Notes on any Interest Payment Date or at maturity will be made available to the Trustee
by 11:00 a.m., New York City time, on such date, unless such date falls on a day which is not a
Business Day, in which case such payments will be made available to the Trustee by 11:00 a.m., New
York City time, on the next Business Day. As soon as possible thereafter, the Trustee will make
such payments to the Depositary.

     SECTION 1.3 Registrar and Paying Agent.

     The Issuer initially appoints the Trustee as Registrar and paying agent with respect to the
Notes. The office or agency in the City and State of New York where Notes may be presented for
registration of transfer or exchange and the Place of Payment for the Notes shall initially be
Wells Fargo Corporate Trust, c/o DTC, 1st Floor, TADS Department, 55 Water Street, New York, New
York 10041.

     SECTION 1.4 Transfer and Exchange.

     The transfer and exchange of Book-Entry Notes or beneficial interests therein shall be
effected through the Depositary, in accordance with Section 2.15 of the Original Indenture and the
rules and procedures of the Depositary therefore.

     SECTION 1.5 Guarantee of the Notes.

     In accordance with Article XIV of the Original Indenture, the Notes will be fully,
unconditionally and absolutely guaranteed on an unsecured, unsubordinated basis by the Parent
Guarantor. Initially, there will be no Subsidiary Guarantors.

     SECTION 1.6 Defeasance and Discharge.

     The Notes shall be subject to satisfaction and discharge and to both legal defeasance and
covenant defeasance as contemplated by Article XI of the Original Indenture.

     SECTION 1.7 Amendment to Section 4.12 of the Original Indenture.

     The last paragraph of Section 4.12 of the Original Indenture is hereby amended and restated in
relation solely to the Notes to read as follows:

     “Notwithstanding the foregoing provisions of this Section, the Parent Guarantor may, and may
permit any Subsidiary to, effect any Sale/Leaseback Transaction that is not excepted by clauses (a)
through (d), inclusive, of this Section, provided that the Attributable Indebtedness from such
Sale/Leaseback Transaction, together with the aggregate principal amount of all other such
Attributable Indebtedness deemed to be outstanding and all outstanding Indebtedness (other

3

 

than the Debt Securities) secured by liens, other than Permitted Liens, upon Principal Properties or upon
any capital stock of any Restricted Subsidiary, do not exceed 10% of Consolidated Net Tangible
Assets.”

     SECTION 1.8 Amendment to Section 4.13 of the Original Indenture.

     The last sentence of Section 4.13 of the Original Indenture is hereby amended and restated in
relation solely to the Notes to read as follows:

     “Notwithstanding the foregoing, the Parent Guarantor may, and may permit any Subsidiary to,
create, assume, incur or suffer to exist any lien, other than a Permitted Lien, upon any Principal
Property or upon any capital stock of any Restricted Subsidiary to secure Indebtedness of the
Parent Guarantor, the Company or any other Person (other than the Debt Securities), without in any
such case making effective provision whereby all the Debt Securities Outstanding under this
Indenture are secured equally and ratably with, or prior to, such Indebtedness so long as such
Indebtedness is secured; provided that the aggregate principal amount of all Indebtedness then
outstanding secured by such lien and all similar liens, together with the aggregate amount of
Attributable Indebtedness deemed to be outstanding in respect of all Sale/Leaseback Transactions
(exclusive of any such Sale/Leaseback Transactions otherwise permitted under clauses (a) through
(d) of Section 4.12), does not exceed 10% of Consolidated Net Tangible Assets.”

ARTICLE II

REDEMPTION

     SECTION 2.1 Redemption.

     The Issuer shall have no obligation to redeem, purchase or repay the Notes pursuant to any
mandatory redemption, sinking fund or analogous provisions or at the option of a Holder thereof.
The Issuer, at its option, may redeem the Notes in accordance with the provisions of paragraph 5 of
the Notes and Article III of the Original Indenture.

ARTICLE III

MISCELLANEOUS PROVISIONS

     SECTION 3.1 Table of Contents, Headings, etc.

     The table of contents and headings of the Articles and Sections of this Twelfth Supplemental
Indenture have been inserted for convenience of reference only, are not to be considered a part
hereof and shall in no way modify or restrict any of the terms or provisions hereof.

     SECTION 3.2 Counterpart Originals.

     The parties may sign any number of copies of this Twelfth Supplemental Indenture. Each signed
copy shall be an original, but all of them together represent the same agreement.

4

 

     SECTION 3.3 Governing Law.

     THIS TWELFTH SUPPLEMENTAL INDENTURE AND THE NOTES SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

5

 

     IN WITNESS WHEREOF, the parties hereto have caused this Twelfth Supplemental Indenture to be
duly executed as of the day and year first above written.

	 	 	 	 	 
	 	ENTERPRISE PRODUCTS OPERATING LLC,

as Issuer

By:  Enterprise Products OLPGP, Inc.

        its sole manager

 	 
	 	By:  	/s/ W. Randall Fowler
 	 
	 	 	Name:  	W. Randall Fowler 	 
	 	 	Title:  	Executive Vice President and

Chief Financial Officer 	 
	 
	 	ENTERPRISE PRODUCTS PARTNERS L.P.,

as Parent Guarantor

By:  Enterprise Products GP, LLC

        its General Partner

 	 
	 	By:  	/s/ W. Randall Fowler
 	 
	 	 	Name:  	W. Randall Fowler 	 
	 	 	Title:  	Executive Vice President and

Chief Financial Officer 	 
	 
	 	WELLS FARGO BANK,

NATIONAL ASSOCIATION,

as Trustee

 	 
	 	By:  	/s/ Patrick T. Giordano
 	 
	 	 	Name:  	Patrick T. Giordano 	 
	 	 	Title:  	Vice President 	 
	 

Twelfth Supplemental Indenture Signature Page

6

 

Exhibit A

FORM OF NOTE

[FACE OF SECURITY]

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST
COMPANY (“DTC”) (55 WATER STREET, NEW YORK, NEW YORK 10041) TO THE COMPANY OR ITS AGENT FOR
REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME
OF CEDE & CO. OR SUCH OTHER NAME AS MAY BE REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND
ANY PAYMENT IS MADE TO CEDE & CO. OR SUCH OTHER ENTITY AS MAY BE REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.]*

[TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN WHOLE, BUT NOT IN PART, TO
NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR’S NOMINEE AND TRANSFERS OF PORTIONS OF
THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET
FORTH IN THE INDENTURE REFERRED TO HEREIN.]* 

Principal Amount

No. ___

$___________, [which amount may be

increased or decreased by the Schedule

of Increases and Decreases in Global Security attached hereto. ]*

ENTERPRISE PRODUCTS OPERATING LLC

5.65% SENIOR NOTE DUE 2013

CUSIP ___________

     ENTERPRISE PRODUCTS OPERATING LLC, a Texas limited liability company (the “Company,” which
term includes any successor under the Indenture hereinafter referred to), for value received,
hereby promises to pay to [Cede & Co.]* or its registered assigns, the principal
sum of _________($_________U.S. dollars, [or such greater or lesser principal sum as is shown
on the attached Schedule of Increases and Decreases in Global Security]*, on April 1,
2013 in such coin and currency of the United States of America as at the time of payment shall be
legal tender for the payment of public and private debts, and to pay interest at an annual rate of
5.65% payable on April 1 and October 1 of each year, to the person in whose

 

			
	*	 	To be included in a Book-Entry Note.

A-1

 

name the Security (as defined on the reverse side of this security) is registered at the close
of business on the record date for such interest, which shall be the preceding March 15 and
September 15 (each, a “Regular Record Date”), respectively, payable commencing on October 1, 2008,
with interest accruing from April 3, 2008, or the most recent date to which interest shall have
been paid.

     Reference is made to the further provisions of this Security set forth on the reverse hereof.
Such further provisions shall for all purposes have the same effect as though fully set forth at
this place.

     The statements in the legends set forth in this Security are an integral part of the terms of
this Security and by acceptance hereof the Holder of this Security agrees to be subject to, and
bound by, the terms and provisions set forth in each such legend.

     This Security is issued in respect of a series of Debt Securities of an initial aggregate of
$400 million in principal amount designated as the 5.65% Senior Notes due 2013 of the Company and
is governed by the Indenture dated as of October 4, 2004 (the “Original Indenture”), duly executed
and delivered by the Company, as issuer, and Enterprise Products Partners L.P., as parent guarantor
(the “Parent Guarantor”), to Wells Fargo Bank, National Association, as trustee (the “Trustee”), as
amended and supplemented by the Tenth Supplemental Indenture, dated as of June 30, 2007, providing
for the Company as the successor issuer (the “Tenth Supplemental Indenture”), and the Twelfth
Supplemental Indenture dated as of April 3, 2008, duly executed by the Company, the Parent
Guarantor and the Trustee (the “Twelfth Supplemental Indenture,” and together with the Original
Indenture and the Tenth Supplemental Indenture dated as of June 30, 2007, the “Indenture”). The
terms of the Indenture are incorporated herein by reference. This Security shall in all respects
be entitled to the same benefits as definitive Debt Securities under the Indenture.

     If and to the extent any provision of the Indenture limits, qualifies or conflicts with any
other provision of the Indenture that is required to be included in the Indenture or is deemed
applicable to the Indenture by virtue of the provisions of the Trust Indenture Act of 1939, as
amended (the “TIA”), such required provision shall control.

     The Company hereby irrevocably undertakes to the Holder hereof to exchange this Security in
accordance with the terms of the Indenture without charge.

     This Security shall not be valid or become obligatory for any purpose until the Trustee’s
Certificate of Authentication hereon shall have been manually signed by the Trustee under the
Indenture.

A-2

 

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed by its sole
manager.

Dated: __________________

	 	 	 	 	 
	 	ENTERPRISE PRODUCTS OPERATING LLC

By:  Enterprise Products OLPGP, Inc.

        its sole manager

 	 
	 	By:  	
 	 
	 	 	Name:  	 	 
	 	 	Title:  	 	 
	 

TRUSTEE’S CERTIFICATE OF AUTHENTICATION:

     This is one of the Debt Securities of the series designated herein referred to in the
within-mentioned Indenture.

	 	 	 	 	 
	 	WELLS FARGO BANK, NATIONAL ASSOCIATION,

as Trustee

 	 
	 	By:  	
 	 
	 	 	Authorized Signatory 	 
	 	 	 	 

A-3

 

	 	 	 	 	 

[REVERSE OF SECURITY]

ENTERPRISE PRODUCTS OPERATING LLC

5.65% SENIOR NOTE DUE 2013

     This Security is one of a duly authorized issue of debentures, notes or other evidences of
indebtedness of the Company (the “Debt Securities”) of the series hereinafter specified, all issued
or to be issued under and pursuant to the Indenture, to which Indenture reference is hereby made
for a description of the rights, limitations of rights, obligations, duties and immunities
thereunder of the Trustee, the Company, the Parent Guarantor and the Holders of the Debt
Securities. The Debt Securities may be issued in one or more series, which different series may be
issued in various aggregate principal amounts, may mature at different times, may bear interest (if
any) at different rates, may be subject to different sinking, purchase or analogous funds (if any)
and may otherwise vary as provided in the Indenture. This Security is one of a series designated
as the 5.65% Senior Notes due 2013 of the Company, in initial aggregate principal amount of $400
million (the “Securities”).

1. Interest.

     The Company promises to pay interest on the principal amount of this Security at the rate of
5.65% per annum.

     The Company will pay interest semi-annually on April 1 and October 1 of each year (each an
“Interest Payment Date”), commencing October 1, 2008. Interest on the Securities will accrue from
the most recent date to which interest has been paid or, if no interest has been paid on the
Securities, from April 3, 2008. Interest will be computed on the basis of a 360-day year
consisting of twelve 30-day months. The Company shall pay interest (including post-petition
interest in any proceeding under any applicable bankruptcy laws) on overdue installments of
interest (without regard to any applicable grace period) and on overdue principal and premium, if
any, from time to time on demand at the same rate per annum, in each case to the extent lawful.

2. Method of Payment.

     The Company shall pay interest on the Securities (except Defaulted Interest) to the persons
who are the registered Holders at the close of business on the Regular Record Date immediately
preceding the Interest Payment Date. Any such interest not so punctually paid or duly provided for
(“Defaulted Interest”) may be paid to the persons who are registered Holders at the close of
business on a special record date for the payment of such Defaulted Interest, or in any other
lawful manner not inconsistent with the requirements of any securities exchange on which such
Securities may then be listed if such manner of payment shall be deemed practicable by the Trustee,
as more fully provided in the Indenture. The Company shall pay principal, premium, if any, and
interest in such coin or currency of the United States of America as at the time of payment shall
be legal tender for payment of public and private debts. Payments in respect of a Global Security
(including principal, premium, if any, and interest) will be made by wire transfer of immediately
available funds to the accounts specified by the Depositary. Payments in respect of Securities in
definitive form (including principal, premium, if any, and interest) will be made at the office or
agency of the Company maintained for such purpose within

A-4

 

The City of New York, which initially will be Wells Fargo Corporate Trust, c/o DTC, 1st Floor,
TADS Department, 55 Water Street, New York, New York 10041, or, at the option of the Company,
payment of interest may be made by check mailed to the Holders on the relevant record date at their
addresses set forth in the Debt Security Register of Holders or at the option of the Holder,
payment of interest on Securities in definitive form will be made by wire transfer of immediately
available funds to any account maintained in the United States, provided such Holder has requested
such method of payment and provided timely wire transfer instructions to the paying agent. The
Holder must surrender this Security to a paying agent to collect payment of principal.

3. Paying Agent and Registrar.

     Initially, Wells Fargo Bank, National Association will act as paying agent and Registrar. The
Company may change any paying agent or Registrar at any time upon notice to the Trustee and the
Holders. The Company may act as paying agent.

4. Indenture.

     This Security is one of a duly authorized issue of Debt Securities of the Company issued and
to be issued in one or more series under the Indenture.

     Capitalized terms herein are used as defined in the Indenture unless otherwise defined herein.
The terms of the Securities include those stated in the Original Indenture, those made part of the
Indenture by reference to the TIA, as in effect on the date of the Original Indenture, and those
terms stated in the Twelfth Supplemental Indenture. The Securities are subject to all such terms,
and Holders of Securities are referred to the Original Indenture, the Twelfth Supplemental
Indenture and the TIA for a statement of them. The Securities of this series are general unsecured
obligations of the Company limited to an initial aggregate principal amount of $400 million;
provided, however, that the authorized aggregate principal amount of such series may be increased
from time to time as provided in the Twelfth Supplemental Indenture.

5. Optional Redemption.

     The Securities are redeemable, at the option of the Company, at any time in whole, or from
time to time in part, at a redemption price (the “Make-Whole Price”) equal to the greater of: (i)
100% of the principal amount of the Securities to be redeemed; or (ii) the sum of the present
values of the remaining scheduled payments of principal and interest (at the rate in effect on the
date of calculation of the redemption price) on the Securities to be redeemed (exclusive of
interest accrued to the Redemption Date) discounted to the Redemption Date on a semi-annual basis
(assuming a 360-day year consisting of twelve 30-day months) at the applicable Treasury Yield plus
25 basis points; plus, in either case, accrued interest to the Redemption Date.

     The actual Make-Whole Price, calculated as provided above, shall be calculated and certified
to the Trustee and the Company by the Independent Investment Banker. For purposes of determining
the Make-Whole Price, the following definitions are applicable:

     “Treasury Yield” means, with respect to any Redemption Date applicable to the Securities, the
rate per annum equal to the semi-annual equivalent yield to maturity (computed as

A-5

 

of the third Business Day immediately preceding such Redemption Date) of the Comparable
Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of
its principal amount) equal to the applicable Comparable Treasury Price for the Redemption Date.

     “Comparable Treasury Issue” means the United States Treasury security selected by the
Independent Investment Banker as having a maturity comparable to the remaining term of the
Securities to be redeemed that would be utilized, at the time of selection and in accordance with
customary financial practice, in pricing new issues of corporate debt securities of comparable
maturity to the remaining terms of the Securities to be redeemed; provided, however, that if no
maturity is within three months before or after the maturity date for the Securities, yields for
the two published maturities most closely corresponding to such United States Treasury security
will be determined and the treasury rate will be interpolated or extrapolated from those yields on
a straight line basis rounding to the nearest month.

     “Independent Investment Banker” means any of Lehman Brothers Inc., Citigroup Global Markets
Inc., J.P. Morgan Securities Inc., Scotia Capital (USA) Inc. and their respective successors, or,
if no such firm is willing and able to select the applicable Comparable Treasury Issue, an
independent investment banking institution of national standing appointed by the Trustee and
reasonably acceptable to the Company.

     “Comparable Treasury Price” means, with respect to any Redemption Date, (a) the average of
four Reference Treasury Dealer Quotations for the Redemption Date, after excluding the highest and
lowest Reference Treasury Dealer Quotations, or (b) if the Independent Investment Banker obtains
fewer than four Reference Treasury Dealer Quotations, the average of all such quotations.

     “Reference Treasury Dealer” means (a) Lehman Brothers Inc., Citigroup Global Markets Inc.,
J.P. Morgan Securities Inc., Scotia Capital (USA) Inc. and their respective successors, and (b) one
other primary U.S. government securities dealer in New York City selected by the Independent
Investment Banker (each, a “Primary Treasury Dealer”); provided, however, that if either of the
foregoing shall cease to be a Primary Treasury Dealer, the Company will substitute therefor another
Primary Treasury Dealer.

     “Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer
and any Redemption Date for the Securities, an average, as determined by an Independent Investment
Banker, of the bid and asked prices for the Comparable Treasury Issue for the Securities (expressed
in each case as a percentage of its principal amount) quoted in writing to an Independent
Investment Banker by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third
Business Day preceding such Redemption Date.

     Except as set forth above, the Securities will not be redeemable prior to their Stated
Maturity and will not be entitled to the benefit of any sinking fund.

     Securities called for optional redemption become due on the Redemption Date. Notices of
optional redemption will be mailed at least 30 but not more than 60 days before the Redemption Date
to each Holder of the Securities to be redeemed at its registered address. The

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notice of optional redemption for the Securities will state, among other things, the amount of
Securities to be redeemed, the Redemption Date, the method of calculating such redemption price and
the place(s) that payment will be made upon presentation and surrender of Securities to be
redeemed. Unless the Company defaults in payment of the redemption price, interest will cease to
accrue on the Redemption Date with respect to any Securities that have been called for optional
redemption. If less than all the Securities are redeemed at any time, the Trustee will select the
Securities to be redeemed on a pro rata basis or by any other method the Trustee deems fair and
appropriate.

     The Securities may be redeemed in part in multiplies of $1,000 only. Any such redemption will
also comply with Article III of the Indenture.

6. Denominations; Transfer; Exchange.

     The Securities are to be issued in registered form, without coupons, in denominations of
$1,000 and integral multiples of $1,000 in excess thereof. A Holder may register the transfer of,
or exchange, Securities in accordance with the Indenture. The Registrar may require a Holder,
among other things, to furnish appropriate endorsements and transfer documents and to pay any taxes
and fees required by law or permitted by the Indenture.

7. Person Deemed Owners.

     The registered Holder of a Security may be treated as the owner of it for all purposes.

8. Amendment; Supplement; Waiver.

     Subject to certain exceptions, the Indenture may be amended or supplemented, and any existing
Event of Default or compliance with any provision may be waived, with the consent of the Holders of
a majority in principal amount of the Outstanding Debt Securities of each series affected. Without
consent of any Holder of a Security, the parties thereto may amend or supplement the Indenture to,
among other things, cure any ambiguity or omission, to correct any defect or inconsistency, or to
make any other change that does not adversely affect the rights of any Holder of a Security. Any
such consent or waiver by the Holder of this Security (unless revoked as provided in the Indenture)
shall be conclusive and binding upon such Holder and upon all future Holders and owners of this
Security and any Securities which may be issued in exchange or substitution herefor, irrespective
of whether or not any notation thereof is made upon this Security or such other Securities.

9. Defaults and Remedies.

     Certain events of bankruptcy or insolvency are Events of Default that will result in the
principal amount of the Securities, together with premium, if any, and accrued and unpaid interest
thereon, becoming due and payable immediately upon the occurrence of such Events of Default. If
any other Event of Default with respect to the Securities occurs and is continuing, then in every
such case the Trustee or the Holders of not less than 25% in aggregate principal amount of the
Securities then Outstanding may declare the principal amount of all the Securities, together with
premium, if any, and accrued and unpaid interest thereon, to be due and payable immediately in the
manner and with the effect provided in the Indenture. Notwithstanding the

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preceding sentence, however, if at any time after such a declaration of acceleration has been
made, the Holders of a majority in principal amount of the Outstanding Securities, by written
notice to the Trustee, may rescind such declaration and annul its consequences if the rescission
would not conflict with any judgment or decree of a court already rendered and if all Events of
Default with respect to the Securities, other than the nonpayment of the principal, premium, if
any, or interest which has become due solely by such declaration acceleration, shall have been
cured or shall have been waived. No such rescission shall affect any subsequent default or shall
impair any right consequent thereon. Holders of Securities may not enforce the Indenture or the
Securities except as provided in the Indenture. The Trustee may require indemnity or security
satisfactory to it before it enforces the Indenture or the Securities. Subject to certain
limitations, Holders of a majority in aggregate principal amount of the Securities then Outstanding
may direct the Trustee in its exercise of any trust or power with respect to the Securities.

10. Trustee Dealings with Company.

     The Trustee under the Indenture, in its individual or any other capacity, may make loans to,
accept deposits from, and perform services for the Company or its Affiliates or any subsidiary of
the Company’s Affiliates, and may otherwise deal with the Company or its Affiliates as if it were
not the Trustee.

11. Authentication.

     This Security shall not be valid until the Trustee signs the certificate of authentication on
the other side of this Security.

12. Abbreviations and Defined Terms.

     Customary abbreviations may be used in the name of a Holder of a Security or an assignee, such
as: TEN COM (tenant in common), TEN ENT (tenants by the entireties), JT TEN (joint tenants with
right of survivorship and not as tenants in common), CUST (Custodian), and U/G/M/A (Uniform Gifts
to Minors Act).

13. CUSIP Numbers.

     Pursuant to a recommendation promulgated by the Committee on Uniform Note Identification
Procedures, the Company has caused CUSIP numbers to be printed on the Securities as a convenience
to the Holders of the Securities. No representation is made as to the accuracy of such number as
printed on the Securities and reliance may be placed only on the other identification numbers
printed hereon.

14. Absolute Obligation.

     No reference herein to the Indenture and no provision of this Security or the Indenture shall
alter or impair the obligation of the Company, which is absolute and unconditional, to pay the
principal of, premium, if any, and interest on this Security in the manner, at the respective
times, at the rate and in the coin or currency herein prescribed.

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15. No Recourse.

     The General Partner and the general partner of the Parent Guarantor and their respective
directors, officers, employees and members, as such, shall have no liability for any obligations of
any Guarantor or the Issuer under the Securities, the Indenture or any Guarantee or for any claim
based on, in respect of, or by reason of, such obligations or their creation. Each Holder by
accepting the Securities waives and releases all such liability. The waiver and release are part
of the consideration for issuance of the Securities.

16. Governing Law.

     This Security shall be construed in accordance with and governed by the laws of the State of
New York.

17. Guarantee.

     The Securities are fully and unconditionally guaranteed on an unsecured, unsubordinated basis
by the Parent Guarantor as set forth in Article XIV of the Indenture, as noted in the Notation of
Guarantee to this Security, and under certain circumstances set forth in the Original Indenture one
or more Subsidiaries of the Parent Guarantor may be required to join in such guarantee.

18. Reliance.

     The Holder, by accepting this Security, acknowledges and affirms that (i) it has purchased the
Security in reliance upon the separateness of Parent Guarantor and the general partner of Parent
Guarantor from each other and from any other Persons, including EPCO, Inc., and (ii) Parent
Guarantor and the general partner of Parent Guarantor have assets and liabilities that are separate
from those of other Persons, including EPCO, Inc.

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NOTATION OF GUARANTEE

     The Parent Guarantor (which term includes any successor Person under the Indenture), has
fully, unconditionally and absolutely guaranteed, to the extent set forth in the Indenture and
subject to the provisions in the Indenture, the due and punctual payment of the principal of, and
premium, if any, and interest on the Securities and all other amounts due and payable under the
Indenture and the Securities by the Company.

     The obligations of the Parent Guarantor to the Holders of Securities and to the Trustee
pursuant to its Guarantee and the Indenture are expressly set forth in Article XIV of the Indenture
and reference is hereby made to the Indenture for the precise terms of the Guarantee.

	 	 	 	 	 
	 	ENTERPRISE PRODUCTS PARTNERS L.P.

By:  Enterprise Products GP, LLC,

         its General Partner

 	 
	 	By:  	 	 
	 	 	Name:  	 	 
	 	 	Title:  	 	 

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ABBREVIATIONS

     The following abbreviations, when used in the inscription on the face of this instrument,
shall be construed as though they were written out in full according to applicable laws or
regulations:

	 	 	 	 	 	 	 	 	 	 	 
	TEN COM

	 	—
	 	as tenants in common
	 	UNIF GIFT MIN ACT —
	 	 

	 	 
	 

	 	 	 	 	 	 	 	(Cust.)	 	 
	TEN ENT

	 	—
	 	as tenants by entireties
	 	Custodian for:
	 	 
	 	 
	 

	 	 	 	 	 	 	 	(Minor)	 	 
	 

	 	 	 	 	 	under Uniform Gifts to	 	 	 	 
	JT TEN

	 	—
	 	as joint tenants
with right of survivorship and
not as tenants in common
	 	Minors Act of
	 	 

(State)	 	 

     Additional abbreviations may also be used though not in the above list.

 

ASSIGNMENT

     FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s) unto

PLEASE INSERT SOCIAL SECURITY OR OTHER

     IDENTIFYING NUMBER OF ASSIGNEE

   
           
          
           
           
             
            
            
              
   

 
Please print or type name and address including postal zip code of assignee

 

 

the within Security and all rights thereunder, hereby irrevocably constituting and appointing

 

to transfer said Security on the books of the Company, with full power of substitution in the
premises.

	 	 	 	 	 	 	 
	Dated __________________

	 	 	 	 

Registered Holder
	 	 

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SCHEDULE OF INCREASES OR DECREASES

IN GLOBAL SECURITY*

     The following increases or decreases in this Global Security have been made:

	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 	 
	 	 	 	 	Amount of	 	Amount of	 	Principal Amount	 	 
	 	 	 	 	Decrease in	 	Increase in	 	of this Global	 	Signature of
	 	 	 	 	Principal	 	Principal Amount of	 	Security following	 	authorized officer
	 	 	 	 	Amount of this	 	this	 	such decrease	 	of Trustee or
	Date of Exchange	 	Global Security	 	Global Security	 	(or increase)	 	Depositary

 

			
	*	 	To be included in a Book-Entry Note.

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