ASSET PURCHASE AGREEMENT


AGREEMENT  as of this 14th day of  November  1997,  by and  among  ENVIROMETRICS
PRODUCTS  COMPANY,  a South  Carolina  corporation  with a  principal  place  of
business at 9229 University Boulevard,  Charleston, South Carolina 29406, Seller
(hereinafter  "Envirometrics"),  Envirometrics,  Inc.,  a  Delaware  Corporation
("EV") and ZELLWEGER  ANALYTICS,  INC., a Texas  corporation  with a principal
place of business at 405 Barclay Boulevard, Lincolnshire, Illinois, 60069, Buyer
(hereinafter "ZA").

WHEREAS,  Envirometrics  is in the air monitoring  business and has manufactured
and sold certain  direct read passive air monitors which it no longer desires to
manufacture  and  sell,  and  owns  certain  Technology  relating  to  that  air
monitoring business ("the Business") that it is willing to sell; and

WHEREAS,  ZA has agreed to accept  certain assets (but not  liabilities)  of the
Business from Envirometrics in conjunction with the settlement of certain claims
of ZA  against  Envirometrics,  as  more  specifically  set  forth  in a  Mutual
Settlement  and  Release  between  the parties  executed  concurrently  herewith
("Releas");

NOW, THEREFORE,  in consideration of the foregoing premises and of the terms and
conditions set forth infra, Envirometrics and ZA agree as follows:

                                       I.
                           Purchase, Sale and Payment

A. Concurrently with the performance of the parties' other obligations under the
Release, at Closing, as hereinafter defined, Envirometrics shall sell to ZA, and
ZA shall purchase from Envirometrics, free and clear of all liabilities, claims,
obligations,  mortgages, pledges, security interests, liens, tax liens and other
encumbrances whatsoever  ("Encumbrances") the following Technology & Trade Names
(the "Asset"):

(1) The ACT Monitoring Card  Technology  (ACT Card),  defined as a direct read
colormetric  passive air monitor that  measures the  airborne  concentration  of
certain  chemicals,  attached  as  Exhibit A hereto,  by changes in the color of
proprietary  chromophores.  Said changes are identified either  Qualitatively by
visually comparing the chromophore to a printed standard or Quantitatively using
an  Electronic  Reader.  Formulations  for the  chemistries  for  the  compounds
outlined in Exhibit A are attached as Exhibit B.

(2) The ACT Monitoring  Card System,  ACT and design,  ACT  Monitoring Card,
Air-Chem Technologies and ACT Card, and the rights to any  trademark, trade
name, service mark, copyright or patent relating thereto or used in conjunction
therewith.

B.  Envirometrics  shall deliver to ZA on November 19, 1997, one or more written
Instruments of Transfer and Assignment reasonably  satisfactory to ZA evidencing
Envirometrics' sale to ZA of all of the foregoing assets, free of encumbrances,
including the Bill of Sale attached as Exhibit C.

C. In  consideration  for and  conditioned  upon delivery of the  Instruments of
Transfer and Assignment identified in  I. B. and the concurrent  performance of
the  parties'  obligations  under the  Release,  ZA shall at Closing  reduce the
unused Prepaid Purchase Deposits that were paid to Envirometrics by ZA under the
Master  Distributorship  Agreement,  dated as of January 1, 1996 by $344,849.90.
Said consideration is part of the Release defined in Exhibit D.


                                       II.
                                     Closing

Closing  ("Closing") of the  transactions  contemplated  by this Agreement shall
take place on November 19, 1997  ("Closing  Dat") at such time and place as the
parties mutually may agree..  The Assets, as itemized supra,  shall be delivered
and transferred at closing.

                                      III.
             Envirometrics Covenants, Representations and Warranties

Envirometrics  covenants,  represents  and  warrants  to  ZA,  which  covenants,
representations and warranties shall survive the Closing, that:

A.  Envirometrics has, and through and/or after the Closing Date will have, good
and marketable title to the Assets  identified in I.A to be sold and delivered
hereunder,  free and clear of all Encumbrances,  and has the requisite authority
to sell and transfer good title to the Assets to ZA.

B. The  manufacture  and sale of the  products of the  Business,  including  the
Assets, as heretofore or hereafter  manufactured and sold by  Envirometrics,  to
the best of the knowledge of Envirometrics and its  shareholders,  directors and
officers,  do not infringe any patent,  trademark,  service  mark,  copyright or
other proprietary rights of any third party and there are no actual,  pending or
threatened claims, suits, investigations, lawsuits or other proceedings relating
to same.

C. No claims, suits,  investigations,  lawsuits or other proceedings are pending
or threatened by any third parties involving the Assets.

D. No consent  by,  approval or  authorization  of, or filing,  registration  or
qualification with, any federal,  state or local governmental authority or other
person,  including any which may be required by any "bulk sal" law, is required
for the execution, delivery or performance of this Agreement by Envirometrics or
in connection with the consummation of the transactions  contemplated  hereby by
Envirometrics.

E.  Envirometrics is a corporation duly organized,  validly existing and in good
standing under the laws of the State of South Carolina.

F.  Envirometrics  has the full corporate power to execute,  deliver and perform
this  Agreement  and has taken all action  required by law, its  certificate  of
incorporation,  its by-laws or otherwise to authorize such  execution,  delivery
and  performance  of this  Agreement  and this  Agreement is a valid and binding
agreement of Envirometrics, enforceable in accordance with its terms.

G.. The execution and delivery of this Agreement do not, and the consummation of
the transactions  contemplated hereby will not: (1) violate any provision of the
certificate  of  incorporation  or by-laws of  Envirometrics;  (2)  violate  any
provision of, or result in the  termination  or  acceleration  of any obligation
under any mortgage, note, lien, lease, franchise,  license,  permit,  agreement,
instrument  or  obligation  to  which  Envirometrics  is a  party  or  by  which
Envirometrics is bound; or (3) violate or conflict with any other restriction of
any kind or character to which Envirometrics or the Business is subject.

H. No approval, authorization, license, permit or other action or finding by any
governmental authority or any third party, shareholder, or board of directors of
Envirometrics  is required  that has not been  obtained in  connection  with the
execution and delivery of this Agreement or the consummation of the transactions
contemplated hereby.

I. No agent or broker or other  persons  acting  pursuant to authority  given by
Envirometrics is entitled to any commission or finder's fee in connection  with
the transaction contemplated by this Agreement.

J. Envirometrics  makes no warranties to ZA other than those expressly set forth
herein.

                                       IV.
                 ZA's Covenants, Representations and Warranties

ZA  covenants,  represents  and  warrants  to  Envirometrics,  which  covenants,
representations and warranties shall survive the Closing, that:

A. ZA is a corporation  duly  organized,  validly  existing and in good standing
under the laws of the State of Texas.

B. ZA has the  full  corporate  power  to  execute,  deliver  and  perform  this
Agreement  and has  taken  all  action  required  by  law,  its  certificate  of
incorporation,  its by-laws or otherwise to authorize such  execution,  delivery
and  performance  of this  Agreement  and this  Agreement is a valid and binding
agreement of ZA enforceable in accordance with its terms.

C. The execution and delivery of this Agreement do not, and the  consummation of
the transactions  contemplated hereby will not: (1) violate any provision of the
certificate of  incorporation or by-laws of ZA; (2) violate any provision of, or
result in the termination or acceleration of any obligation  under any mortgage,
note, lien, franchise,  license, permit, agreement,  instrument or obligation to
which ZA is a party or by which ZA is bound; or (3) violate or conflict with any
other  restriction  of any kind or  character  to which  ZA or the  Business  is
subject.

D. No approval, authorization, license, permit or other action or finding by any
governmental authority or any third party, shareholder, or board of directors of
ZA is required that has not been  obtained in connection  with the execution and
delivery of this Agreement or the consummation of the transactions  contemplated
hereby.

E. ZA knows of no pending or threatened  government  investigation,  request for
information  or action by any third  party  which  would  prohibit or prevent or
claim  damages as a result of this  Agreement or the  transactions  contemplated
hereby and there is no  litigation  pending or threatened to the knowledge of ZA
which would affect ZA's ability to perform its obligation hereunder.

F. No agent or broker or other persons acting  pursuant to authority given by ZA
is entitled to any commission or finder's fee in connection with the transaction
contemplated by this Agreement.


                                       V.
                               Sales and Use Taxes

Envirometrics  shall be responsible to pay all sales,  use and other taxes which
are due as a result of the transfer and  conveyances  of any of the Assets,  and
shall indemnify and hold ZA harmless from any taxes, expenses,  costs (including
reasonable attorneys' fees),  liabilities and judgments arising from or relating
to any failure of Envirometrics to pay such taxes when due.


                                       VI.
                                Business Transfer

A.  Envirometrics  and ZA agree  upon the text of a letter in the form  attached
hereto as Exhibit E. Said Letters from Envirometrics  shall be addressed to each
of   Envirometrics   customers   which   purchased   products  of  the  business
("Customers").  These letters shall be sent to customers on, or before  November
29, 1997.

B. Neither ZA nor Envirometrics shall issue any press release or make any public
statement  regarding  the terms of this  Agreement  without  the  consent of the
other, which shall not be reasonably  withheld,  except where a press release or
public statement is required by any law or regulation.


                                      VII.
                                 Indemnification

A. EVRM and Envirometrics shall release, defend, indemnify and hold harmless ZA,
its officers,  directors and  employees,  from and against all expenses,  costs,
liabilities and judgments (including reasonable attorneys' fees) arising from or
relating  to  claims  relating  to  Envirometrics' operation  of the  Business,
including,  but not limited to claims by purchasers,  alleged owners or users of
products of the Business for bodily injury,  death, physical or property damage,
infringement of intellectual  property rights, loss of wages or other damages or
claims  allegedly  resulting  from in  whole  or in part a  defect  in  products
designed or manufactured or sold by Envirometrics  prior to the Closing Date and
claims  resulting from or based upon any breach by  Envirometrics  of any of its
representations,   covenants,   warranties  or  agreements   contained  in  this
Agreement.

B. ZA shall  release,  defend,  indemnify and hold harmless  Envirometrics,  its
officers,  directors and employees,  from claims solely  relating to ZA's use of
the  technology  and/or  the  ACT Monitoring  Card  name or  mark on  products
manufactured  by ZA after the Closing Date or based upon any breach by ZA of any
of its  representations,  covenants,  warranties or agreements contained in this
Agreement.

C. The parties' obligations hereunder shall survive the Closing.



                                       IX.
                         Further Assurances and Actions

Subject to the provisions of this Agreement,  EV and Envirometrics  will execute
all documents and take all such further actions as ZA shall reasonably  request,
and ZA will execute all documents and take all such actions as Envirometrics may
reasonably  request,  prior  to,  at or  after  the  Closing  Date in  order  to
consummate the  transactions  provided  herein and to accomplish the purposes of
this Agreement.




                                       X.
                                   No Brokers

Envirometrics  represents  and warrants to ZA and ZA represents  and warrants to
Envirometrics that all negotiations relative to this Agreement have been carried
on by it or its representatives directly with the other without the intervention
of any person in their behalf and that no broker brought about this Agreement on
their behalf.


                                       XI.
                        Non-Competition/Non-Solicitation


EV and Envirometrics, individually and collectively, and expressly including any
agent, employee,  officer, parent or subsidiary,  branch, division or affiliate,
agree that for a period of three years following the date of Closing,  they will
not:

     (a) of their own right or in concert with any other person,  corporation or
     business entity,  knowingly, for themselves or for any person,  corporation
     or business entity, call upon, solicit,  divert or take away, or attempt to
     solicit, divert or take away any of the Customers;

     (b) of their own right or in concert with any person,  corporation or other
     business entity, knowingly engage, for themselves or on account of or as an
     agent or servant of another,  directly or  indirectly,  in the  business of
     distributing,  wholesaling,  selling or marketing of Assets to Customers or
     in the  marketing or selling of products to  Customers  designed to compete
     with the Assets; and

     (c) of their own right or in concert with any other person,  corporation or
     business entity,  knowingly, for themselves or for any person,  corporation
     or business entity,  will not directly or indirectly,  in the United States
     and Canada,  engage in any business or related activities which is the same
     or  similar  to the  Business  or  which  designs,  manufactures,  markets,
     distributes  or sells  goods or  services  the  same as or  similar  to the
     Business, the Assets or any component thereof.

The  parties  acknowledge  that the  giving of the  foregoing  restrictions  and
covenants  to ZA were a condition  upon which ZA entered  into the  transactions
contemplated hereby and that the limitations of this section have been carefully
considered  by the  parties and are deemed to be  reasonable  and  necessary  to
protect the value of the Assets and that EV and  Envirometrics are entering into
the foregoing without duress.

In the event of a breach or threatened  breach of any of EV or  Envirometrics'
foregoing obligations, ZA shall be entitled to temporary or permanent injunctive
relief, in addition to whatever other legal or equitable relief may be available
to it. EV and Envirometrics further acknowledge that in the event of a breach or
threatened  breach of the foregoing,  ZA has no adequate  remedy at law and that
any  monetary  damages  which  may  result  as a  consequence  of its  breach or
threatened   breach  may  be  difficult  or  impossible   to  measure.   EV  and
Envirometrics  hereby waive and agree not to assert,  now or in the future,  the
claim or defense that a remedy at law exists and is adequate.

                                      XII.
                 Conditions Precedent to Obligations of Parties

A. The obligation of ZA to purchase the assets is subject to the  fulfillment on
or  prior  to the  Closing  Date as the  case  may be of  each of the  following
conditions:

(1)  Envirometrics  shall have complied in all material respects with all of its
agreements  and  convenants  contained  herein to be performed as of the time of
Closing  including  those  under  the  Release  and  all of the  representations
contained herein shall be true and accurate in all material  respects on, as of,
and after the Closing Date.

(2) No order of any court or  governmental  regulatory  authority  or body which
restrains or prohibits the transactions  contemplated  hereby shall be in effect
on the Closing Date, and no suit,  proceeding,  or investigation by a government
agency or third  party to enjoin  the  transaction  contemplated  hereby or seek
damages or other relief as a result thereof shall be pending or threatened as of
the Closing Date.

B. The obligation of  Envirometrics  to execute and deliver the Bill of Sale and
the other  documents  required  to be  provided  hereunder,  attached  hereto as
Exhibit C, is subject to:

(1) ZA shall have complied in all material  respects with all of its  agreements
and covenants contained herein to be performed as of the time of Closing and all
of the  representations  contained  herein  shall  be true and  accurate  in all
material respects on, as of, and after the Closing Date.

(2) No order of any court or  governmental  regulatory  authority  or body which
restrains or prohibits the transactions  contemplated  hereby shall be in effect
on the Closing Date and no suits  proceeding,  or  investigation by a government
agency or third  party to enjoin  the  transaction  contemplated  hereby or seek
damages or other relief as a result thereof shall be pending or threatened as of
the Closing Date.



                                      XIII.
                                     Notices

All notices,  requests,  demands or other  communications  hereunder shall be in
writing and shall be deemed to have been duly given if delivered  or mailed,  by
registered or certified mail, postage prepaid to the following addresses:



         If to Envirometrics:   Envirometrics Products Company
                                9229 University Boulevard
                                Charleston, SC  29406
                                Attn:  Walter H. "Skip" Elliott, III, President

         If to ZA:              Zellweger Analytics, Inc.
                                405 Barclay Boulevard
                                Lincolnshire, Illinois  60069
                                Attn:  Jon McAlear, President and CEO

or at such other  addresses as each such party may furnish to the other  parties
in writing.

                                      XIV.
                                  Choice of Law

This Agreement shall be governed by and construed in accordance with the laws of
the state of Illinois, without regard to its conflicts of law principles.

                                       XV.
                                Entire Agreement

This instrument and other  documents  referenced  herein  constitutes the entire
understanding  between  Envirometrics and ZA with respect to the Business and as
such supersedes all prior representations, agreements and understandings between
them with respect to such subject matter.  This Agreement or any term hereof may
be changed,  waived,  discharged or terminated  only in writing  executed by the
duly  authorized  officers of EV and  Envirometrics  and ZA, which writing shall
indemnify  this  Agreement  and shall  express the plan or  intention to modify,
waive or terminate it.

IN WITNESS  WHEREOF,  the parties  have  executed  this  Agreement by their duly
authorized officers as of the date hereof.

                               ENVIROMETRICS PRODUCTS COMPANY


                               ------------------------------------------------
                               By:  Walter H. Elliott, III
                               President

                               ZELLWEGER ANALYTICS, INC.


                               ------------------------------------------------
                               By:  Jon McAlear
                               President and CEO


                                  BILL OF SALE

                                    EXHIBIT C

FOR VALUE RECEIVED, ENVIROMETRICS PRODUCTS COMPANY, a South Carolina Corporation
(hereinafter  called  "Seller")  has  bargained,  sold,  conveyed,  assigned and
delivered  unto  ZELLWEGER  ANALYTICS,  INC., a Texas  Corporation  (hereinafter
called "Purchaser"), pursuant to an Asset Purchase Agreement between the parties
dated  November  14,  1997  (the  "Agreement"),  all of the  assets  rights  and
properties  listed and  described in Exhibit A,  attached  hereto and  expressly
incorporated herein by reference (hereinafter called the "Assets").

TO HAVE AND TO HOLD all and singular the  above-described  Assets, and all title
thereto and interest therein, unto Purchaser, its successors and assigns, to its
own use and behoove forever.

Seller warrants and represents to, and covenants and agrees with Purchaser, that
Seller is the lawful owner of all of said  Assets;  that Seller has the right to
sell,  convey,  assign and deliver the same unto  Purchaser as herein  provided;
that the  purchase  price for the Assets has been fully paid;  that there are no
liens or encumbrances whatsoever affecting the Assets.

The undersigned  represents and warrants that he has all necessary and requisite
power and authority to execute the within Bill of Sale on behalf of the Seller.

IN WITNESS WHEREOF, Seller has set its hand and seal this November 18, 1997.


                                 ENVIROMETRICS PRODUCTS COMPANY


                                 ----------------------------------------------
                                 By:  Walter H. Elliott, III
                                 President

STATE OF SOUTH CAROLINA
COUNTY OF CHARLESTON

Subscribed and sworn to before me this 18th date of November,  1997 by Walter H.
Elliott,  III as the voluntary act and deed of Envirometrics  Products  Company,
duly authorized.


                                  ----------------------------------------------
                                  Notary Public
                                  My Commission Expires :___________________

                                    Exhibit A
                                (To Bill of Sale)

                                   ASSET LIST


(1) The ACT Monitoring Card  Technology  (ACT Card),  defined as a direct read
colormetric  passive air monitor that  measures the  airborne  concentration  of
certain  chemicals,  by changes in the color of proprietary  chromophores.  Said
changes  are  identified   either   Qualitatively  by  visually   comparing  the
chromophore to a printed standard or Quantitatively using an Electronic Reader.

(2) Formulations for all ACT Monitoring Cards.

(3) The ACT Monitoring  Card System,  ACT and design,  ACT  Monitoring  Card,
Air-Chem Technologies and ACT Card.

(4) Bills of materials, drawings,  formulations and manufacturing procedures for
badges.

(5) Customer List(s).