<PAGE>
                                                                    Exhibit 10.3


This Note and the securities represented hereby have not been registered under
the Securities Act of 1933, as amended (the "Act"), or under the securities or
blue sky laws of any State, and may not be sold, or otherwise transferred, in
absence of such registration or an exemption therefrom under such Act and under
any such applicable State laws, or in violation of the provisions of this Note.



                           SPECTRUMEDIX CORPORATION



                                6% SECURED NOTE
                               Due July 9, 2004

$600,000

                          Date of Issue: July 9, 2001

     SpectruMedix Corporation, a Delaware corporation (the "Company"), for value
received, herewith promises to pay to the I. Reich Family Limited Partnership, a
Delaware limited partnership, or to its order, (together with any assignee,
jointly or severally, the "Holder") on the Due Date (as hereinafter defined),
the sum of six hundred thousand dollars ($600,000) or, if less, so much hereof
as may be outstanding from time to time, as set forth on the Schedule attached
hereto (the "Principal Amount") and to pay interest on the Principal Amount at
the rate of six percent (6%) per annum as provided herein.  Capitalized terms
used but not otherwise defined herein shall have the meanings ascribed thereto
in the Securities Purchase Agreement between the Company and the Holder dated as
of July 9, 2001 (the "Securities Purchase Agreement").  In furtherance thereof,
and in consideration of the premises, covenants, promises, representations and
warranties hereinafter set forth the Borrower hereby agrees as follows:

1.   Interest.  Interest on the Principal Amount outstanding from time to time
     --------
as set forth on the Schedule hereto shall accrue at the rate of 6.00% per annum,
shall be based on a three hundred sixty (360) day year of twelve (12) thirty
(30) day months and shall be payable quarterly as accrued in arrears on each
July 9, October 9, January 9, and April 9 until this Note shall have been paid
in full.  All payments of both principal and interest shall be made at the
address of the Holder hereof as it appears in the books and records of the
Company, or at such other place as may be designated by the Holder hereof.  If
any payment of principal or interest on this Note shall become due on a day
other than any day that is not a Saturday, a Sunday or a day on which banks are
required or permitted to be closed in the State of New York (a "Business Day"),
such payment shall be made on the next succeeding Business Day and such
extension of time shall in such case be included in computing interest in
connection with such payment.  Payments of principal and interest are to be made
in lawful money of the United States.  Notwithstanding the
<PAGE>

foregoing sentence, the Borrower may elect to (i) make scheduled interest
payments on this Note in the form of a PIK Note (the "PIK Note"), in form
substantially similar to this Note or (ii) defer any interest payment until the
Due Date, in which event interest shall accrue on any interest payment so
deferred at the rate of six percent (6%) per annum.

2.   Maturity.  This Note shall mature July 9, 2004, at which time all unpaid
     --------
principal and interest shall be due and payable in full.

3.   Optional Prepayment.  The Company may at any time or from time to time
     -------------------
prepay all or any portion of this Note, provided that each such prepayment shall
                                        --------
be in a minimum amount of $25,000 or integral multiples thereof.

4.   Security.  The obligations of the Borrower under this Note are secured by a
     --------
valid, perfected, enforceable and first priority lien on and security interest
in the Collateral described in the Security Agreement dated as of July 9, 2001
between the Company and Holder, and each other agreement or other instrument now
existing or hereafter created providing collateral security for the payment or
performance of the Company's obligations hereunder and under the Securities
Purchase Agreement.

5.   Defaults.  The occurrence of any of the following shall constitute an Event
     --------
of Default hereunder:

     (a)  default in the payment of all or any part of the principal or interest
on the Note as and when the same shall become due and payable, whether at
maturity, by declaration or otherwise;

     (b)  failure on the part of the Company duly to observe or perform any of
the covenants or agreements contained herein on its part to be performed, and
the continuance of such failure for thirty (30) days or the Security Agreement;

     (c)  the Company shall commence a voluntary case or other proceeding
seeking liquidation, reorganization or other relief with respect to itself or
its debts under any bankruptcy, insolvency or other similar law now or
hereinafter in effect or seeking the appointment of a trustee, receiver
liquidator, custodian or other similar official of it or any substantial part of
its property, or shall consent to any such relief or to the appointment of or
taking possession by any such official in an involuntary case or other
proceeding commenced against it, or shall make a general assignment for the
benefit of creditors, or shall fail generally to pay its debts as they become
due, or shall take corporate action to authorize any of the foregoing;

     (d)  an involuntary case or other proceeding shall be commenced against the
Company seeking liquidation, reorganization or other relief with respect to it
or its debts under any bankruptcy, insolvency or other similar law now or
hereafter in effect or seeking the appointment of a trustee, receiver,
liquidator, custodian or other similar official of it or any substantial part of
its property, and such involuntary case or other proceeding shall remain
undismissed and unstayed for a period of sixty (60) days; or an order for relief
shall be entered against the Company under the federal bankruptcy laws as now or
hereafter in effect; or

                                      -2-
<PAGE>

     (e)  Ilan Reich (or a successor acceptable to him) shall cease to be the
Chairman and Chief Executive Officer of the Company;

then, and in each and every such case, unless the principal of the Note shall
have already become due an payable, the Holder, by notice in writing to the
Company (the "Acceleration Notice"), may declare the entire principal amount of
this Note, together with interest accrued thereon, to be due an payable
immediately, and upon any such declaration the same shall become immediately due
and payable.

6.   Voting Rights.  In the event that, for any reason, the shares of Series C
     -------------
Preferred Stock, par value $.00115 per share, shall cease to have thirteen (13)
votes for each share of Common Stock issuable upon conversion of a share of
Series C Preferred Stock, then the holder of this Note shall have the right to
vote, together with the holders of the Company's Common Stock, and shall have
one vote for each share of Common Stock issuable upon conversion of this Note

7.   Failure to Act and Waiver.  No failure or delay by the Holder to require
     -------------------------
the performance of any term or terms of this Note or to exercise any right, or
any remedy shall constitute a waiver of any such term or of any right or of any
default, nor shall such delay or failure preclude the Holder from exercising any
such right, power or remedy at any later time or times.

8.   Consent to Jurisdiction.  The Company hereby agrees and consents that any
     -----------------------
action, suit or proceeding arising out of this Note may be brought in any
appropriate court in the State of New York including the United States District
Court for the Southern District of New York, or in any other court having
jurisdiction over the subject matter, all at the sole election of the Holder
hereof, and by the issuance and execution of this Note, the Company irrevocably
consents to the jurisdiction of each such court.

9.   No Assignment.  The Company may not assign its obligations under this Note
     -------------
without the prior written consent of the Holder.  Any purported assignment
prohibited hereby shall be void.

10.  Notices.  All notices and communications under this Note shall be given as
     -------
set forth in Section 8.2 of the Securities Purchase Agreement.

                                      -3-
<PAGE>

11.  Governing Law.  In all respects, including all matters of construction,
     -------------
validity and performance, this note and the obligations arising hereunder shall
be governed by, and construed and enforced in accordance with, the laws of the
state of New York applicable to contracts made and performed in such state,
without regard to the principles thereof regarding conflict of laws, and any
applicable laws of the united states of America.

                             *    *    *    *    *


     IN WITNESS WHEREOF, the Company has caused this Note to be duly executed
under its corporate seal on the date of issue above stated.


                                         SPECTRUMEDIX CORPORATION


                                         By: /s/ Stephen Wertheimer
                                             ------------------------------
                                         Name: Stephen Wertheimer
                                         Title: Secretary & President

                                      -4-
<PAGE>

                                6% Secured Note
                                   Schedule
                                   --------

<TABLE>
<CAPTION>
                                          Payments                        Unpaid Principal               Name of Person
        Date                  Principal              Interest             Balance of Note               Making Notation
--------------------     ------------------   --------------------    ------------------------    --------------------------
<S>                      <C>                  <C>                     <C>                         <C>


</TABLE>


                                      -5-