[Federal Register Volume 62, Number 235 (Monday, December 8, 1997)]
[Proposed Rules]
[Pages 64532-64542]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-32045]



40 CFR Part 51

RIN 2060-AG88

Preparation, Adoption, and Submittal of State Implementation 
Plans; Appendix M, Test Method 207

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule and notice of public hearing.


SUMMARY: The purpose of this proposed rule is to add a validated 
stationary source test method for the measurement of isocyanate 
emissions from stationary sources to the Code of Federal Regulations. 
This method, validated according to EPA Method 301 criteria, would be 
used to reliably collect and analyze gaseous isocyanate emissions from 
stationary sources such as flexible foam manufacturers, automobile 
paint spray booths, and the pressed board industry. Specifically, 
methylene diphenyl diisocyanate (MDI), methyl isocyanate (MI), 
hexamethylene 1,6-diisocyanate (HDI), and 2,4-toluene diisocyanate 
(TDI) are the gaseous pollutants in source emissions to be measured. 
The test method is entitled, ``A Method for Measuring Isocyanates in 
Stationary Source Emissions,'' and will be added to 40 CFR Part 51, 
Appendix M, as Test Method 207. This method will provide a tool for 
state and local governments, representatives of private industry, and 
the U.S. Government to reliably monitor stationary sources for 
isocyanate emissions with a validated stationary source method. 
Additionally, this method will allow the U.S. Environmental Protection 
Agency to comply with the requirements of the Clean Air Act Amendments 
of 1990 for monitoring these hazardous air pollutants. Prior to the 
development of this method, no other ``validated'' method has been 
available to monitor these highly reactive hazardous emissions. 
Isocyanates are used extensively in the production of polyurethane 
materials such as flexible foam, enamel wire coatings, paint 
formulations, and in binders for the pressed board industry. A public 
hearing will be held, if requested, to provide interested persons an 
opportunity for oral presentation of data, views, or arguments 
concerning the proposed method.

DATES: Comments. Comments must be received on or before February 23, 
    Public Hearing. If anyone contacts EPA requesting to speak at a 
public hearing by December 29, 1997, a public hearing will be held 
January 22, 1998 beginning at 10:00 a.m. Persons interested in 
attending the hearing should call the contact mentioned under ADDRESSES 
to verify that a meeting will be held.
    Request to Speak at Hearing. Persons wishing to present oral 
testimony must contact EPA by December 29, 1997.

ADDRESSES: Comments. Comments should be submitted (in duplicate if 
possible) to: Central Docket Section (Mail Code: 6102), Attention: 
Docket Number A-96-06, U.S. Environmental Protection Agency, Room M-
1500, First Floor, Waterside Mall, 401 M Street, S.W., Washington, D.C. 
    Public Hearing. If anyone contacts EPA requesting a public hearing, 
it will be held at EPA's Emission Measurement Center, Research Triangle 
Park, North Carolina. Persons interested in attending the hearing or 
wishing to present oral testimony should notify Frank Wilshire, Methods 
Branch (MD-44), Air

[[Page 64533]]

Measurements Research Division, National Exposure Research Laboratory, 
U.S. Environmental Protection Agency, Research Triangle Park, North 
Carolina 27711, telephone number (919) 541-2785.
    Docket. Docket No. A-96-06, containing materials relevant to this 
rulemaking, is available for public inspection and copying between 8:00 
a.m. and 5:30 p.m., Monday through Friday, at EPA's Air Docket Section, 
Room M-1500, First Floor, Waterside Mall, 401 M Street, S.W., 
Washington, D.C. 20460. A reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: Frank Wilshire, at the address listed 
under Public Hearing, or Gary McAlister, Source Characterization Group 
B (MD-19), Emissions Monitoring and Analysis Division, U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711, telephone number (919) 541-1062.


I. The Rulemaking

A. Summary of Proposed Method

    The U.S. Environmental Protection Agency, under the authority of 
Title III of the Clean Air Act Amendments of 1990, requires the 
development of a validated (per EPA Method 301 criteria) stationary 
source sampling and analysis method for the following isocyanates: 
methyl isocyanate, methylene diphenyl diisocyanate, hexamethylene 1,6-
diisocyanate, and 2,4-toluene diisocyanate. The isocyanate sampling 
method developed is a modification of the EPA Method 5 sampling train 
(no filter and the addition of impingers), employing impingers and a 
derivatizing reagent [1-(2-pyridyl)piperazine in toluene] to 
immediately stabilize the isocyanates upon collection. Collected 
samples are analyzed under laboratory conditions sufficient to separate 
and quantify the isocyanates, using high performance liquid 
chromatography with ultra violet detection.

B. Comments and Responses on Draft

    The proposed method is available by request. Requests should be 
made to: Frank Wilshire (MD-44), Methods Branch, U.S. Environmental 
Protection Agency, Research Triangle Park, NC 27711. To date, over 
thirty-five copies of the isocyanate method have been requested by 
representatives of the private sector, state and local governments, 
industry trade associations, and the Canadian Government.
    On June 7, 1995 a presentation was made before members of the 
Analytical and Environmental Subcommittee of the International 
Isocyanate Institute to review the method and address the timetable and 
procedure for including the isocyanate method in the Code of Federal 
Regulations (CFR). Members of the Subcommittee were enthusiastic about 
the method and inquired when it might be included in the Code of 
Federal Regulations. To date, no technical comments have been received 
from other sources. Oral comments have been received by many of those 
requesting copies of the method, suggesting publication of the method 
in the CFR. This action would establish a reference method for the 
collection and analysis of isocyanates from stationary sources and aid 
in standardizing monitoring of isocyanate emissions from these sources.

II. Administrative Requirements

A. Public Hearing

    A public hearing will be held, if requested, to discuss the 
proposed rulemaking in accordance with Section 307(d)(5) of the Clean 
Air Act. Persons wishing to make oral presentations should contact EPA 
at the address given in the ADDRESSES section of this preamble. Oral 
presentation will be limited to 15 minutes each. Any member of the 
public may file a written statement with the EPA before, during, or 
within 30 days after the hearing. Written statements should be 
addressed to the Central Air Docket Section address given in the 
ADDRESSES section of this preamble.
    A verbatim transcript of the hearing and written statements will be 
available for public inspection and copying during normal working hours 
at EPA's Central Air Docket Section in Washington, D.C. (see ADDRESSES 
section of this preamble).

B. Docket

    The docket is an organized and complete file of all the information 
submitted to or otherwise considered by the EPA in the development of 
this proposed rulemaking. The principal purposes of the docket are to: 
(1) Allow interested parties to identify and locate documents so that 
they can effectively participate in the rulemaking process, and (2) 
serve as the record in case of judicial review except for interagency 
review materials [Section 307(d)(7)(A)].

C. Office of Management and Budget Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), the EPA 
is required to judge whether a regulation is ``significant'' and 
therefore subject to Office of Management and Budget (OMB) review and 
the requirements of this Executive Order to prepare a regulatory impact 
analysis. The Order defines ``significant regulatory action'' as one 
that is likely to result in a rule that may: (1) Have an annual effect 
on the economy of $100 million or more or adversely affect in a 
material way the economy, a sector of the economy, productivity, 
competition, jobs, the environment, public health or safety, or State, 
local, or tribal governments or communities; (2) create a serious 
inconsistency or otherwise interfere with an action taken or planned by 
another agency; (3) materially alter the budgetary impact of 
entitlements, grants, user fees, or loan programs, or the rights and 
obligation of recipients thereof; or (4) raise novel legal or policy 
issues arising out of legal mandates, the President's priorities, or 
the principles set forth in the Executive Order. Pursuant to the terms 
of the Executive Order, this action has been determined to be ``not 

D. Regulatory Flexibility Act Compliance

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to conduct a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements unless that Agency certifies 
that the rule will not have a significant economic impact on a 
substantial number of small entities. Small entities include small 
businesses, small not-for-profit enterprises, and small governmental 
jurisdictions. This proposed rule would not have a significant impact 
on a substantial number of small entities because the overall impact of 
these amendments is a net decrease in requirements on all entities 
including small entities. Therefore, I certify that this action will 
not have a significant economic impact on a substantial number of small 

E. Paperwork Reduction Act

    The rule does not change any information collection requirements 
subject of Office of Management and Budget review under the Paperwork 
Reduction Act of 1980, 44 U.S.C. 3501 et seq.

F. Unfunded Mandates

    Under Section 202 of the Unfunded Mandates Reform Act of 1995 
(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA 
must prepare a budgetary impact statement to accompany any proposed or 
final rule

[[Page 64534]]

that includes a Federal mandate that may result in estimated costs to 
State, local, or tribal governments in the aggregate; or to the private 
sector, of $100 million or more. Under Section 205, EPA must select the 
most cost-effective and least burdensome alternative that achieves the 
objectives of the rule and is consistent with statutory requirements. 
Section 203 requires EPA to establish a plan for significantly or 
uniquely impacted by the rule.
    EPA has determined that the action proposed today does not include 
a Federal mandate that may result in estimated costs of $100 million or 
more to either State, local, or tribal governments in the aggregate, or 
to the private sector, nor does this action significantly or uniquely 
impact small governments, because this action contains no requirements 
that apply to such governments or impose obligations upon them. 
Therefore, the requirements of the Unfunded Mandates Act do not apply 
to this action.

List of Subjects in 40 CFR Part 51

    Environmental protection, Air pollution control, Hazardous air 
pollutants, Polyurethane production, Flexible foam manufacturing, 
Enamel wire coatings, Manufactured wood products, Isocyanates.

    Dated: November 25, 1997.
Carol M. Browner,

    It is proposed that 40 CFR part 51 be amended to read as follows:
    1. The authority citation for part 51 continues to read as follows:

    Authority: 42 U.S.C. 7401, 7411, 7412, 7413, 7414, 7470-7479, 
7501-7508, 7601, and 7602.

    2. Appendix M to part 51 is amended by adding Method 207 in 
numerical order to read as follows:

Appendix M to Part 51--Recommended Test Methods for State 
Implementation Plans

* * * * *
    Method 207--A Method for Measuring Isocyanates in Stationary Source 

    Note: This method is not inclusive with respect to 
specifications (e.g., equipment and supplies) and sampling 
procedures essential to its performance. Some material is 
incorporated by reference from other EPA methods. Therefore, to 
obtain reliable results, persons using this method should have a 
thorough knowledge of at least Method 1, Method 2, Method 3, and 
Method 5 found in Part 60 of this title.
    1.0  Scope and Application.
    1.1  This method is applicable to the collection and analysis of 
isocyanate compounds from the emissions associated with 
manufacturing processes. The following is a list of the isocyanates 
and the manufacturing process at which the method has been 

            Compound name               CAS No.      limits a                 Manufacturing process             
2,4-Toluene Diisocyanate (TDI)......        584-8          106  Flexible Foam Production.                       
1,6-Hexamethylene Diisocyanate (HDI)        822-0          396  Paint Spray Booth.                              
Methylene Diphenyl Diisocyanate             101-6          112  Pressed Board Production.                       
 (MDI).                                       8-8                                                               
Methyl Isocyanate (MI)..............        624-8          228  Not used in production.                         
a Estimated detection limits are based on a sample volume of 1 m\3\ and a 10-ml sample extraction volume.       

    2.0  Summary of Method.
    2.1  Gaseous and/or aerosol isocyanates are withdrawn from an 
emission source at an isokinetic sampling rate and are collected in 
a multicomponent sampling train. The primary components of the train 
include a heated probe, three impingers containing the derivatizing 
reagent in toluene, an empty impinger, an impinger containing 
charcoal and an impinger containing silica gel.
    2.2  The impinger contents are concentrated to dryness under 
vacuum, brought to volume with acetonitrile (ACN) and analyzed with 
a high pressure liquid chromatograph (HPLC).
    3.0  Definitions. Not Applicable.
    4.0  Interferences.
    4.1  The greatest potential for interference comes from an 
impurity in the derivatizing reagent, 1-(2-pyridyl)piperazine (1,2-
PP). This compound may interfere with the resolution of MI from the 
peak attributed to unreacted 1,2-PP.
    4.2   Other interferences that could result in positive or 
negative bias are; (1) alcohols that could compete with the 1,2-PP 
for reaction with an isocyanate; and (2) other compounds that may 
coelute with one or more of the derivatized isocyanates.
    4.3  Method interferences may be caused by contaminants in 
solvents, reagents, glassware, and other sample processing hardware. 
All these materials must be routinely shown to be free from 
interferences under conditions of the analysis by preparing and 
analyzing laboratory method (or reagent) blanks.
    4.3.1  Glassware must be cleaned thoroughly before using. The 
glassware should be washed with laboratory detergent in hot water 
followed by rinsing with tap water and distilled water. The 
glassware may be cleaned by baking in a glassware oven at 400  deg.C 
for at least one hour. After the glassware has cooled, the glassware 
should be rinsed three times with methylene chloride and three times 
with acetonitrile. Volumetric glassware should not be heated to 400 
deg.C. Instead, after washing and rinsing, volumetric glassware may 
be rinsed with ACN followed by methylene chloride and allowed to dry 
in air.
    4.3.2  The use of high purity reagents and solvents helps to 
reduce interference problems in sample analysis.
    5.0  Safety.
    5.1  The toxicity of each reagent has been precisely defined. 
Each isocyanate can produce dangerous levels of hydrogen cyanide 
(HCN). The exposure to these chemicals must be reduced to the lowest 
possible level by whatever means available. The laboratory is 
responsible for maintaining a current awareness file of Occupational 
Safety and Health Administration (OSHA) regulations regarding safe 
handling of the chemicals specified in this method. A reference file 
of material safety data sheets should also be made available to all 
personnel involved in the chemical analysis. Additional references 
to laboratory safety are available.
    6.0  Equipment and Supplies.
    6.1  Sample Collection. The following items are required for 
sample collection:
    6.1.1 A schematic of the sampling train used in this method is 
shown in Figure 207-1. This sampling train configuration is adapted 
from EPA Method 5 procedures, and, as such, most of the required 
equipment is identical to that used in EPA Method 5 determinations. 
The only new component required is a condenser coil.
    6.1.2  Construction details for the basic train components are 
given in APTD-0581 (see Martin, 1971, in Section 16.0, References); 
commercial models of this equipment are also available. 
Additionally, the following subsections list changes to APTD-0581 
and identify allowable train configuration modifications.
    6.1.3  Basic operating and maintenance procedures for the 
sampling train are described in APTD-0576 (see Rom, 1972, in Section 
16.0, References). As correct usage is important in obtaining valid 
results, all users

[[Page 64535]]

should refer to APTD-0576 and adopt the operating and maintenance 
procedures outlined therein unless otherwise specified. The sampling 
train consists of the components detailed below.  Probe Nozzle. Glass with sharp, tapered (30 deg. angle) 
leading edge. The taper shall be on the outside to preserve a 
constant internal diameter. The nozzle shall be buttonhook or elbow 
design. A range of nozzle sizes suitable for isokinetic sampling 
should be available in increments of 0.16 cm (\1/16\ in.), e.g., 
0.32-1.27 cm (\1/8\-\1/2\ in.), or larger if higher volume sampling 
trains are used. Each nozzle shall be calibrated according to the 
procedures outlined in Paragraph 10.1.  Probe liner. Borosilicate or quartz-glass tubing with a 
heating system capable of maintaining a probe gas temperature of 
12014  deg.C (24825  deg.F) at the exit end 
during sampling. (The tester may opt to operate the equipment at a 
temperature lower than that specified.) Because the actual 
temperature at the outlet of the probe is not usually monitored 
during sampling, probes constructed according to APTD-0581 and using 
the calibration curves of APTD-0576 (or calibrated according to the 
procedure outlined in APTD-0576) are considered acceptable. Either 
borosilicate or quartz glass probe liners may be used for stack 
temperatures up to about 480  deg.C (900  deg.F). Quartz glass 
liners shall be used for temperatures between 480 and 900  deg.C 
(900 and 1650  deg.F). (The softening temperature for borosilicate 
is 820  deg.C (1508  deg.F), and for quartz glass 1500  deg.C (2732 
deg.F).) Water-cooling of the stainless steel sheath will be 
necessary at temperatures approaching and exceeding 500  deg.C.  Pitot tube. Type S, as described in Section 2.1 of 
promulgated EPA Method 2 or other appropriate devices (see Vollaro, 
1976 in Section 16.0, References). The pitot tube shall be attached 
to the probe to allow constant monitoring of the stack-gas velocity. 
The impact (high-pressure) opening plane of the pitot tube shall be 
even with or above the nozzle entry plane (see EPA Method 2, Figure 
2-6b) during sampling. The Type S pitot tube assembly shall have a 
known coefficient, determined as outlined in Section 4.0 of 
promulgated EPA Method 2.  Differential Pressure Gauge. Inclined manometer or 
equivalent device as described in Section 2.2 of promulgated EPA 
Method 2. One manometer shall be used for velocity-head (delta P) 
readings and the other for orifice differential pressure (delta H) 
readings.  Impinger Train. Six 500 mL impingers are connected in 
series with leak-free ground-glass joints following immediately 
after the heated probe. The first impinger shall be of the 
Greenburg-Smith design with the standard tip. The remaining five 
impingers shall be of the modified Greenburg-Smith design, modified 
by replacing the tip with a 1.3-cm (\1/2\-in.) I.D. glass tube 
extending about 1.3 cm (\1/2\ in.) from the bottom of the outer 
cylinder. The first, second and third impingers shall contain known 
quantities of the derivatizing reagent in toluene with the first 
impinger containing 300 mL and 200 mL in the second and third. The 
fourth impinger remains empty. The fifth impinger is filled with a 
known amount (\2/3\ full) of activated charcoal and the sixth with a 
known amount of desiccant. A water-jacketed condenser is placed 
between the outlet of the first impinger and the inlet to the second 
impinger to reduce the evaporation of toluene from the first 
impinger.  Metering System. The necessary components are a vacuum 
gauge, leak-free pump, temperature sensors capable of measuring 
temperature to within 3  deg.C (5.4  deg.F), dry-gas meter capable 
of measuring volume to within 1%, and related equipment, as shown in 
Figure 207-1. At a minimum, the pump should be capable of four cubic 
feet per minute (cfm) free flow, and the dry-gas meter should have a 
recording capacity of 0-999.9 cubic feet (cu ft) with a resolution 
of 0.005 cu ft. Other metering systems capable of maintaining 
sampling rates within 10% of isokineticity and of determining sample 
volumes to within 2% may be used. The metering system must be used 
with a pitot tube to enable checks of isokinetic sampling rates. 
Sampling trains using metering systems designed for flow rates 
higher than those described in APTD-0581 and APTD-0576 may be used, 
if the specifications of this method are met.  Barometer. Mercury, aneroid, or other barometer capable 
of measuring atmospheric pressure to within 2.5 mm Hg (0.1 in. Hg). 
Often the barometric reading may be obtained from a nearby National 
Weather Service station, in which case the station value (which is 
the absolute barometric pressure) is requested and an adjustment for 
elevation differences between the weather station and sampling point 
is applied at a rate of minus 2.5 mm Hg (0.1 in. Hg) per 30-m (100 
ft) elevation increase (vice versa for elevation decrease).  Gas density determination equipment. Temperature sensor 
and pressure gauge (as described in Sections 2.3 and 2.4 of EPA 
Method 2, and gas analyzer, if necessary (as described in EPA Method 
3). The temperature sensor ideally should be permanently attached to 
the pitot tube or sampling probe in a fixed configuration such that 
the tip of the sensor extends beyond the leading edge of the probe 
sheath and does not touch any metal. Alternatively, the sensor may 
be attached just before use in the field. Note, however, that if the 
temperature sensor is attached in the field, the sensor must be 
placed in an interference-free arrangement with respect to the Type 
S pitot tube openings (see promulgated EPA Method 2, Figure 2-7. As 
a second alternative, if a difference of no more than 1% in the 
average velocity measurement is to be introduced, the temperature 
sensor need not be attached to the probe or pitot tube.  Calibration/Field-Preparation Record. A permanent bound 
laboratory notebook, in which duplicate copies of data may be made 
as they are being recorded, is required for documenting and 
recording calibrations and preparation procedures (i.e., silica gel 
tare weights, quality assurance/quality control check results, dry-
gas meter, and thermocouple calibrations, etc.). The duplicate 
copies should be detachable and should be stored separately in the 
test program archives.
    6.2  Sample Recovery. The following items are required for 
sample recovery:
    6.2.1  Probe Liner. Probe and nozzle brushes; Teflon 
bristle brushes with stainless steel wire or Teflon 
handles are required. The probe brush shall have extensions 
constructed of stainless steel, Teflon, or inert material 
at least as long as the probe. The brushes shall be properly sized 
and shaped to brush out the probe liner and the probe nozzle.
    6.2.2  Wash Bottles. Three. Teflon or glass wash 
bottles are recommended; polyethylene wash bottles should not be 
used because organic contaminants may be extracted by exposure to 
organic solvents used for sample recovery.
    6.2.3  Glass Sample Storage Containers. Chemically resistant, 
borosilicate amber glass bottles, 500-mL or 1,000-mL. Bottles should 
be tinted to prevent the action of light on the sample. Screw-cap 
liners shall be either Teflon or constructed to be leak-
free and resistant to chemical attack by organic recovery solvents. 
Narrow-mouth glass bottles have been found to leak less frequently.
    6.2.4  Graduated Cylinder and/or Balances. To measure impinger 
contents to the nearest 1 ml or 1 g. Graduated cylinders shall have 
subdivisions not >2 mL. Laboratory balances capable of weighing to 
0.5 g or better are required.
    6.2.5  Plastic Storage Containers. Screw-cap polypropylene or 
polyethylene containers to store silica gel and charcoal.
    6.2.6  Funnel and Rubber Policeman. To aid in transfer of silica 
gel or charcoal to container (not necessary if silica gel is weighed 
in field).
    6.2.7  Funnels. Glass, to aid in sample recovery.
    6.3  Crushed Ice. Quantities ranging from 10-50 lb may be 
necessary during a sampling run, depending on ambient air 
    6.4  Stopcock Grease. The use of silicone grease is not 
permitted. Silicone grease usage is not necessary if screw-on 
connectors and Teflon sleeves or ground-glass joints are 
    6.5  Sample Analysis. The following items are required for 
sample analysis.
    6.5.1  Rotary Evaporator. Buchii Model EL-130 or equivalent.
    6.5.2  1000 ml round bottom flask for use with a rotary 
    6.5.3  Separatory Funnel. 500-ml or larger, with 
Teflon Stopcock.
    6.5.4  Glass Funnel. Short stemmed or equivalent.
    6.5.5  Vials. 15-ml capacity with Teflon lined caps.
    6.5.6  Class A Volumetric Flasks. 10-ml for bringing samples to 
volume after concentration.
    6.5.7  Filter Paper. Scientific Products Grade 370 Qualitative 
or equivalent.
    6.5.8  Buchner Funnel. Porcelain with 100 mm ID or equivalent.
    6.5.9  Erlenmeyer Flask. 500-ml with side arm and vacuum source.
    6.5.10  HPLC with at least a binary pumping system capable of a 
programmed gradient.

[[Page 64536]]

    6.5.11  Column. Alltech Altima C18, 250 mm  x  4.6 mm ID, 
5m particle size (or equivalent).
    6.5.12  Guard Column. Alltech Hypersil ODS C18, 10 mm  x  4.6 mm 
ID, 5m particle size (or equivalent).
    6.5.13  UV detector at 254 nm.
    6.5.14  Data system for measuring peak areas and retention 
    7.0  Reagents and Standards.
    7.1  Sample Collection Reagents.
    7.1.1  Charcoal. Activated, 6-16 mesh. Used to absorb toluene 
vapors and prevent them from entering the metering device. Use once 
with each train and discard.
    7.1.2  Silica Gel. Indicating type, 6-16 mesh. If previously 
used, dry at 175  deg.C (350  deg.F) for 2 hours before using. New 
silica gel may be used as received. Alternatively, other types of 
desiccants (equivalent or better) may be used, subject to the 
approval of the Administrator.
    7.1.3  Impinger Solution. The impinger solution is prepared in 
the laboratory by mixing a known amount of 1-(2-pyridyl) piperazine 
(purity 99.5+ %) in toluene (HPLC grade or equivalent). The actual 
concentration of 1,2-PP should be approximately four times the 
amount needed to ensure that the capacity of the derivatizing 
solution is not exceeded. This amount shall be calculated from the 
stoichiometric relationship between 1,2-PP and the isocyanate of 
interest and preliminary information about the concentration of the 
isocyanate in the stack emissions. A concentration of 130 
g/ml of 1,2-PP in toluene can be used as a reference point. 
This solution should be prepared in the laboratory, stored in a 
refrigerated area away from light, and used within ten days of 
    7.2  Sample Recovery Reagents.
    7.2.1  Toluene. Distilled-in-glass grade is required for sample 
recovery and cleanup (see Note to 7.2.2 below).
    7.2.2  Acetonitrile. Distilled-in-glass grade is required for 
sample recovery and cleanup.

    Note: Organic solvents from metal containers may have a high 
residue blank and should not be used. Sometimes suppliers transfer 
solvents from metal to glass bottles; thus blanks shall be run 
before field use and only solvents with a low blank value (<0.001%) 
shall be used.

    7.3  Reagent grade chemicals should be used in all tests. All 
reagents shall conform to the specifications of the Committee on 
Analytical Reagents of the American Chemical Society, where such 
specifications are available.
    7.3.1  Toluene, C6H5CH3. HPLC 
Grade or equivalent.
    7.3.2  Acetonitrile, CH3CN (ACN). HPLC Grade or 
    7.3.3  Methylene Chloride, CH2CL2. HPLC 
Grade or equivalent.
    7.3.4  Hexane, C6H14. Pesticide Grade or 
    7.3.5  Water, H2O. HPLC Grade or equivalent.
    7.3.6  Ammonium Acetate, 
    7.3.7  Acetic Acid (glacial), CH3CO2H.
    7.3.8  1-(2-Pyridyl) piperazine, (1,2-pp). Aldrich, 99.5+% or 
    7.3.9  Absorption Solution. Prepare a solution of 1-(2-pyridyl) 
piperazine in toluene at a concentration of 40 mg/300 ml. This 
solution is used for method blanks and method spikes.
    7.3.10  Ammonium Acetate Buffer Solution (AAB). Prepare a 
solution of ammonium acetate in water at a concentration of 0.1 M by 
transferring 7.705 g of ammonium acetate to a 1000 ml volumetric 
flask and diluting to volume with HPLC Grade water. Adjust pH to 6.2 
with glacial acetic acid.
    8.0  Sample Collection, Preservation, Storage and Transport.
    8.1  Because of the complexity of this method, field personnel 
should be trained in and experienced with the test procedures in 
order to obtain reliable results.
    8.2  Preliminary Field Determinations.
    8.2.1  Select the sampling site and the minimum number of 
sampling points according to EPA Method 1 or as specified by the 
Administrator. Determine the stack pressure, temperature, and range 
of velocity heads using EPA Method 2. It is recommended that a leak-
check of the pitot lines (see promulgated EPA Method 2, Section 3.1) 
be performed. Determine the stack gas moisture content using EPA 
Approximation Method 4 or its alternatives to establish estimates of 
isokinetic sampling-rate settings. Determine the stack-gas dry 
molecular weight, as described in promulgated EPA Method 2, Section 
3.6. If integrated EPA Method 3 sampling is used for molecular 
weight determination, the integrated bag sample shall be taken 
simultaneously with, and for the same total length of time as, the 
sample run.
    8.2.2  Select a nozzle size based on the range of velocity heads 
so that changing the nozzle size in order to maintain isokinetic 
sampling rates is not necessary. During the run, do not change the 
nozzle. Ensure that the proper differential pressure gauge is chosen 
for the range of velocity heads encountered (see Section 2.2 of 
promulgated EPA Method 2).
    8.2.3  Select a suitable probe liner and probe length so that 
all traverse points can be sampled. For large stacks, to reduce the 
length of the probe, consider sampling from opposite sides of the 
    8.2.4  A typical sample volume to be collected is 1 dscm (35.31 
dscf). The sample volume can be adjusted as required by analytical 
detection limit constraints and/or estimated stack concentrations. A 
maximum limit should be determined to avoid exceeding the capacity 
of the reagent.
    8.2.5  Determine the total length of sampling time needed to 
obtain the identified minimum volume by comparing the anticipated 
average sampling rate with the volume requirement. Allocate the same 
time to all traverse points defined by EPA Method 1. To avoid 
timekeeping errors, the length of time sampled at each traverse 
point should be an integer or an integer plus one-half min.
    8.2.6  In some circumstances (e.g., batch cycles) sampling for 
shorter times at the traverse points may be necessary and to obtain 
smaller gas-sample volumes. In these cases, the Administrator's 
approval must first be obtained.
    8.3  Preparation of Sampling Train.
    8.3.1  During preparation and assembly of the sampling train, 
keep all openings where contamination can occur covered with 
Teflon film or aluminum foil until just before assembly 
or until sampling is about to begin.
    8.3.2  Place 300 ml of the impinger absorbing solution in the 
first impinger and 200 ml each in the second and third impingers. 
The fourth impinger shall remain empty. The fifth and sixth 
impingers shall have 400 g of preweighed charcoal and 200-300 g of 
silica gel, respectively.
    8.3.3  When glass probe liners are used, install the selected 
nozzle using a Viton-A O-ring when stack temperatures 
are <260  deg.C (500  deg.F) and a woven glass-fiber gasket when 
temperatures are higher. See APTD-0576 (Rom, 1972) for details. 
Other connecting systems using Teflon ferrules may be 
used. Mark the probe with heat-resistant tape or by another method 
to denote the proper distance into the stack or duct for each 
sampling point.
    8.3.4  Set up the train as shown in Figure 207-1. During 
assembly, do not use any silicone grease on ground-glass joints. 
Connect all temperature sensors to an appropriate potentiometer/
display unit. Check all temperature sensors at ambient temperature.
    8.3.5  Place crushed ice around the impingers.
    8.3.6  Turn on the condenser coil coolant recirculating pump and 
begin monitoring the gas entry temperature. Ensure proper gas entry 
temperature before proceeding and again before any sampling is 
initiated. It is important that the gas entry temperature not exceed 
50  deg.C (122  deg.F), thus reducing the loss of toluene from the 
first impinger.
    8.3.7  Turn on and set the probe heating systems at the desired 
operating temperatures. Allow time for the temperature to stabilize.
    8.4  Leak-Check Procedures.
    8.4.1  Pre-test leak-check.  Because the additional connection in the train (over 
the EPA Method 5 Train) increases the possibility of leakage, a pre-
test leak-check is required.  After the sampling train has been assembled, turn on 
and set the probe heating systems at the desired operating 
temperatures. Allow time for the temperatures to stabilize. If a 
Viton A O-ring or other leak-free connection is used in 
assembling the probe nozzle to the probe liner, leak-check the train 
at the sampling site by plugging the nozzle and pulling a 381-mm Hg 
(15-in. Hg) vacuum. Leakage rates greater than 4% of the average 
sampling rate or >0.00057 m\3\/min (0.020 cfm), whichever is less, 
are unacceptable.

    Note: A lower vacuum may be used, if it is not exceeded during 
the test.   The following leak-check instructions for the sampling 
train described in APTD-0576 and APTD-0581 may be helpful. Start the 
pump with the fine-adjust valve fully open and the coarse-adjust 
valve completely closed. Partially open the coarse-adjust valve and 
slowly close the fine-adjust valve until the desired vacuum is 
reached. Do not reverse direction of the fine-adjust valve; this 
will cause impinger contents to back up in the train. If the desired 
vacuum is exceeded, either leak-check at this higher

[[Page 64537]]

vacuum or end the leak-check, as shown below, and start over.   When the leak-check is completed, first slowly remove 
the plug from the inlet to the probe. When the vacuum drops to 127 
mm (5 in.) Hg or less, immediately close the coarse-adjust valve. 
Switch off the pumping system and reopen the fine-adjust valve. Do 
not reopen the fine-adjust valve until the coarse-adjust valve has 
been closed. This prevents the reagent in the impingers from being 
forced backward into the probe and silica gel from being entrained 
backward into the fifth impinger.
    8.4.2   Leak-Checks During Sampling Run.   If, during the sampling run, a component change 
becomes necessary, a leak-check shall be conducted immediately after 
the interruption of sampling and before the change is made. The 
leak-check shall be done according to the procedure outlined in 
Paragraph 8.4.1, except that it shall be done at a vacuum greater 
than or equal to the maximum value recorded up to that point in the 
test. If the leakage rate is no greater than 0.00057 m\3\/min (0.020 
cfm) or 4% of the average sampling rate (whichever is less), the 
results are acceptable, and no correction will need to be applied to 
the total volume of dry gas metered. If a higher leakage rate is 
obtained, the tester shall void the sampling run.

    Note: Any ``correction'' of the sample volume by calculation 
reduces the integrity of the pollutant concentration data generated 
and must be avoided.  Immediately after a component change, and before 
sampling is restarted, a leak-check similar to a pre-test leak-check 
must also be conducted.
    8.4.3  Post-Test Leak-Check.  A leak-check of the sampling train is mandatory at the 
conclusion of each sampling run. The leak-check shall be performed 
with the same procedures as those with the pre-test leak-check, 
except that it shall be conducted at a vacuum greater than or equal 
to the maximum value reached during the sampling run. If the leakage 
rate is no greater than 0.00057 m3/min (0.020 cfm) or 4% 
of the average sampling rate (whichever is less), the results are 
acceptable, and no correction need be applied to the total volume of 
dry gas metered. If, however, a higher leakage rate is obtained, the 
tester shall either record the leakage rate, correct the sample 
volume (as shown in Section 6.3 of Method 5), and consider the data 
obtained of questionable reliability, or void the sampling run.
    8.5  Sampling-Train Operation.
    8.5.1  During the sampling run, maintain an isokinetic sampling 
rate to within 10% of true isokinetic, unless otherwise specified by 
the Administrator.
    8.5.2  For each run, record the data required on a data sheet 
such as the one shown in Figure 207-2. Be sure to record the initial 
dry-gas meter reading. Record the dry-gas meter readings at the 
beginning and end of each sampling time increment, when changes in 
flow rates are made before and after each leak-check, and when 
sampling is halted. Take other readings shown by Figure 207-2 at 
least once at each sample point during each time increment and 
additional readings when significant changes (20% variation in 
velocity-head readings) require additional adjustments in flow rate. 
Level and zero the manometer. Because the manometer level and zero 
may drift due to vibrations and temperature changes, make periodic 
checks during the traverse.
    8.5.3  Clean the stack access ports before the test run to 
eliminate the chance of collecting deposited material. To begin 
sampling, verify that the probe heating system is at the specified 
temperature, remove the nozzle cap, and verify that the pitot tube 
and probe are properly positioned. Position the nozzle at the first 
traverse point, with the tip pointing directly into the gas stream. 
Immediately start the pump and adjust the flow to isokinetic 
conditions. Nomographs, which aid in the rapid adjustment of the 
isokinetic sampling rate without excessive computations, are 
available. These nomographs are designed for use when the Type S 
pitot-tube coefficient is 0.840.02 and the stack-gas 
equivalent density (dry molecular weight) is equal to 
294. APTD-0576 details the procedure for using the 
nomographs. If the stack-gas molecular weight and the pitot-tube 
coefficient are outside the above ranges, do not use the nomographs 
unless appropriate steps (Shigehara, 1974, in Section 16.0, 
References) are taken to compensate for the deviations.
    8.5.4  When the stack is under significant negative pressure 
(equivalent to the height of the impinger stem), take care to close 
the coarse-adjust valve before inserting the probe into the stack, 
to prevent the impinger solutions from backing into the probe. If 
necessary, the pump may be turned on with the coarse-adjust valve 
    8.5.5  When the probe is in position, block off the openings 
around the probe and stack access port to prevent unrepresentative 
dilution of the gas stream.
    8.5.6  Traverse the stack cross section, as required by EPA 
Method 1 or as specified by the Administrator, being careful not to 
bump the probe nozzle into the stack walls when sampling near the 
walls or when removing or inserting the probe through the access 
port, in order to reduce the chance of extracting deposited 
    8.5.7  During the test run, make periodic adjustments to keep 
the temperature of the condenser at the proper levels; add more ice 
and, if necessary, salt to maintain the temperature. Also, 
periodically check the level and zero of the manometer.
    8.5.8  A single train shall be used for the entire sample run, 
except in cases where simultaneous sampling is required in two or 
more separate ducts or at two or more different locations within the 
same duct, or in cases where equipment failure requires a change of 
trains. In all other situations, the use of two or more trains will 
be subject to the approval of the Administrator.
    8.5.9  At the end of the sample run, close the coarse-adjust 
valve, remove the probe and nozzle from the stack, turn off the 
pump, record the final dry-gas meter reading, and conduct a post-
test leak-check. Also, leak-check the pitot lines as described in 
EPA Method 2. The lines must pass this leak-check in order to 
validate the velocity-head data.
    8.5.10  Calculate percent isokineticity (see Section 6.11 of 
Method 5) to determine whether the run was valid or another test run 
should be performed.
    8.6  Sample Recovery.
    8.6.1  Preparation.  Proper cleanup procedure begins as soon as the probe is 
removed from the stack at the end of the sampling period. Allow the 
probe to cool. When the probe can be handled safely, wipe off all 
external particulate matter near the tip of the probe nozzle and 
place a cap over the tip to prevent losing or gaining particulate 
matter. Do not cap the probe tip tightly while the sampling train is 
cooling down because this will create a vacuum in the train.  Before moving the sample train to the cleanup site, 
remove the probe from the sample train and cap the open outlet, 
being careful not to lose any condensate that might be present. Cap 
the impinger inlet. Remove the umbilical cord from the last impinger 
and cap the impinger.  Transfer the probe and the impinger/condenser assembly 
to the cleanup area. This area should be clean and protected from 
the weather to reduce sample contamination or loss.  Save a portion of all washing solutions (toluene/
acetonitrile) used for the cleanup as a blank. Transfer 200 ml of 
each solution directly from the wash bottle being used and place 
each in a separate, prelabeled glass sample container.  Inspect the train prior to and during disassembly and 
note any abnormal conditions.
    8.6.2  Sample Containers.  Container No. 1. With the aid of an assistant, rinse 
the probe/nozzle first with toluene and then with acetonitrile by 
tilting and rotating the probe while squirting the solvent into the 
upper end of the probe so that all of the surfaces are wetted with 
solvent. When using these solvents insure that proper ventilation is 
available. Let the solvent drain into the container. If particulate 
is visible, use a Teflon brush to loosen/remove the 
particulate and follow with a second rinse of each solvent. After 
weighing the contents of the first impinger, add it to container No. 
1 along with the toluene and acetonitrile rinses of the impinger. 
(Acetonitrile will always be the final rinse.) If two liquid layers 
are present add both to the container. After all components have 
been collected in the container, seal the container, mark the liquid 
level on the bottle and add the proper label.  Container No. 2. After weighing the contents of the 
second, third and fourth impingers, add them to container No. 2 
along with the toluene and acetonitrile rinses of the impingers, the 
condenser and all connecting glassware. After all components have 
been collected in the container, seal the container, mark the liquid 
level on the bottle and add the proper label.
    8.6.3  The contents of the fifth and sixth impingers (charcoal 
and silica gel) can be discarded after they have been weighed.
    8.6.4  Sample Preparation for Shipment. Prior to shipment, 
recheck all sample containers to ensure that the caps are well 
secured. Seal the lids with Teflon tape. Ship

[[Page 64538]]

all samples upright, packed in ice, using the proper shipping 
materials as prescribed for hazardous materials. The samples must be 
stored at 4 deg.C between the time of sampling and concentration. 
Each sample should be extracted and concentrated within 30 days 
after collection and analyzed within 30 days after extraction. The 
extracted sample must be stored at 4 deg.C.
    9.0  Quality Control.
    9.1  Sampling. See EPA Manual 600/4-77-027b for Method 5 quality 
    9.1.1  Field Blanks. Field blanks must be submitted with the 
samples collected at each sampling site. The field blanks include 
the sample bottles containing aliquots of sample recovery solvents, 
and impinger solutions. At a minimum, one complete sampling train 
will be assembled in the field staging area, taken to the sampling 
area, and leak-checked at the beginning and end of the testing (or 
for the same total number of times as the actual test train). The 
probe of the blank train shall be heated during the sample test. The 
train will be recovered as if it were an actual test sample. No 
gaseous sample will be passed through the sampling train.
    9.1.2  Reagent Blanks. An aliquot of toluene, acetonitrile and 
the impinger solution will be collected in the field as separate 
samples and returned to the laboratory for analysis to evaluate 
artifacts that may be observed in the actual samples.
    9.2  Analysis.
    9.2.1  The correlation coefficient for the calibration curve 
must be 0.995 or greater. If the correlation coefficient is less 
than 0.995, the HPLC system should be examined for problems, and a 
new calibration curve should be prepared and analyzed.
    9.2.2  A solvent blank should be analyzed daily to verify that 
the system is not contaminated.
    9.2.3  A calibration standard should be analyzed prior to any 
samples being analyzed, after every 10 injections and at the end of 
the sample set. Samples must be bracketed by calibration standards 
that have a response that does not vary by more than 10% of the 
target value. If the calibration standards are outside the limit, 
the samples must be reanalyzed after it is verified that the 
analytical system is in control.
    9.2.4  A method blank should be prepared and analyzed for every 
10 samples concentrated (Section 11.4).
    9.2.5  A method spike should be prepared and analyzed for every 
20 samples. The response for each analyte should be within 20% of 
the expected theoretical value of the method spike (Section 11.3).
    10.0  Calibration and Standardization.

    Note: Maintain a laboratory log of all calibrations.

    10.1  Probe Nozzle. Probe nozzles shall be calibrated before 
their initial use in the field. Using a micrometer, measure the 
inside diameter of the nozzle to the nearest 0.025 mm (0.001 in.). 
Make measurements at three separate places across the diameter and 
obtain the average of the measurements. The difference between the 
high and low numbers shall not exceed 0.1 mm (0.004 in.). When 
nozzles become nicked, dented, or corroded, they shall be reshaped, 
sharpened, and recalibrated before use. Each nozzle shall be 
permanently and uniquely identified.
    10.2  Pitot Tube Assembly. The Type S pitot tube assembly shall 
be calibrated according to the procedure outlined in Section 4 of 
promulgated EPA Method 2, or assigned a nominal coefficient of 0.84 
if it is not visibly nicked, dented, or corroded and if it meets 
design and intercomponent spacing specifications.
    10.3  Metering System.
    10.3.1  Before its initial use in the field, the metering system 
shall be calibrated according to the procedure outlined in APTD-
0576. Instead of physically adjusting the dry-gas meter dial 
readings to correspond to the wet-test meter readings, calibration 
factors may be used to correct the gas meter dial readings 
mathematically to the proper values. Before calibrating the metering 
system, it is suggested that a leak-check be conducted. For metering 
systems having diaphragm pumps, the normal leak-check procedure will 
not detect leakages within the pump. For these cases the following 
leak-check procedure is suggested: Make a 10-min calibration run at 
0.00057 m\3\/min (0.020 cfm); at the end of the run, take the 
difference of the measured wet-test and dry-gas meter volumes and 
divide the difference by 10 to get the leak rate. The leak rate 
should not exceed 0.00057 m\3\/min (0.020 cfm).
    10.3.2  After each field use, the calibration of the metering 
system shall be checked by performing three calibration runs at a 
single intermediate orifice setting (based on the previous field 
test). The vacuum shall be set at the maximum value reached during 
the test series. To adjust the vacuum, insert a valve between the 
wet-test meter and the inlet of the metering system. Calculate the 
average value of the calibration factor. If the calibration has 
changed by more than 5%, recalibrate the meter over the full range 
of orifice settings, as outlined in APTD-0576.
    10.3.3  Leak-check of metering system. That portion of the 
sampling train from the pump to the orifice meter (see Figure 207-1) 
should be leak-checked prior to initial use and after each shipment. 
Leakage after the pump will result in less volume being recorded 
than is actually sampled. Close the main valve on the meter box. 
Insert a one-hole rubber stopper with rubber tubing attached into 
the orifice exhaust pipe. Disconnect and vent the low side of the 
orifice manometer. Close off the low side orifice tap. Pressurize 
the system to 13-18 cm (5-7 in.) water column by blowing into the 
rubber tubing. Pinch off the tubing and observe the manometer for 1 
min. A loss of pressure on the manometer indicates a leak in the 
meter box. Leaks, if present, must be corrected.

    Note: If the dry-gas-meter coefficient values obtained before 
and after a test series differ by >5%, either the test series shall 
be voided or calculations for test series shall be performed using 
whichever meter coefficient value (i.e., before or after) gives the 
lower value of total sample volume.

    10.4  Probe Heater. The probe-heating system shall be calibrated 
before its initial use in the field according to the procedure 
outlined in APTD-0576. Probes constructed according to APTD-0581 
need not be calibrated if the calibration curves in APTD-0576 are 
    10.5  Temperature Sensors. Each thermocouple must be permanently 
and uniquely marked on the casing; all mercury-in-glass reference 
thermometers must conform to ASTM E-1 63 specifications. 
Thermocouples should be calibrated in the laboratory with and 
without the use of extension leads. If extension leads are used in 
the field, the thermocouple readings at ambient air temperatures, 
with and without the extension lead, must be noted and recorded. 
Correction is necessary if the use of an extension lead produces a 
change >1.5%.
    10.5.1  Dry-gas meter thermocouples. For the thermocouples used 
to measure the temperature of the gas leaving the impinger train 
three-point calibration at ice-water, room-air, and boiling-water 
temperatures is necessary. Accept the thermocouples only if the 
readings at all three temperatures agree to 2 deg.C 
(3.6 deg.F) with those of the absolute value of the reference 
    10.5.2  Probe and stack thermocouples. For the thermocouples 
used to indicate the probe and stack temperatures, a three-point 
calibration at ice-water, boiling-water, and hot-oil-bath 
temperatures must be performed; it is recommended that room-air 
temperature be added, and that the thermometer and the thermocouple 
agree to within 1.5% at each of the calibration points. A 
calibration curve (equation) may be constructed (calculated) and the 
data extrapolated to cover the entire temperature range suggested by 
the manufacturer.
    10.6  Barometer. Adjust the barometer initially and prior to 
each test series to agree to within 2.5 mm Hg (0.1 in. 
Hg) of the mercury barometer or the corrected barometric pressure 
value reported by a nearby National Weather Service Station (same 
altitude above sea level).
    10.7  Balance. Calibrate the balance before each test series, 
using Class-S standard weights; the weights must be within 
0.5% of the standards, or the balance must be adjusted 
to meet these limits.
    10.8  High Performance Liquid Chromatograph. Establish the 
retention times for each of the isocyanates of interest using the 
chromatographic conditions provided in Section 11.5.1. The retention 
times provided in Table 11.5.1-1 are provided as a guide to relative 
retention times. Prepare derivatized calibration standards 
(concentrations expressed in terms of the free isocyanate, Section 
12.4) according to the procedure in Section 10.8.1. Calibrate the 
chromatographic system using the external standard technique 
(Section 10.8.2)
    10.8.1  Preparation of calibration standards. Prepare a 100 
g/ml stock solution of the isocyanates of interest from the 
individual isocyanate-urea derivative as prepared in Sections 11.1.1 
and 11.1.2. This is accomplished by dissolving 1 mg of each 
isocyanate-urea derivative in 10 ml of ACN. Calibration standards 
are prepared from this stock solution by making appropriate 
dilutions of aliquots of the stock into ACN. Calibrate the 
instrument from 1 to 20 g/ml for HDI, TDI and MDI, and from 
1 to 80 g/ml for MI using at least six calibration points.
    10.8.2  External standard calibration procedure. Analyze each 

[[Page 64539]]

calibration standard using the chromatographic conditions listed in 
Section 11.5.1 and tabulate peak area against concentration 
injected. The working calibration curve must be verified on each 
working day by the measurement of one or more calibration standards. 
If the response for any analyte varies from the target response by 
more than 10%, the test must be repeated using a fresh calibration 
standard(s) after it is verified that the analytical system is under 
control. Alternatively, a new calibration curve may be prepared for 
that compound.
    11.0  Analytical Procedure.
    11.1  Preparation of isocyanate derivatives.
    11.1.1  HDI, TDI, MDI.  Dissolve 500 mg of each isocyanate in individual 100 
ml aliquots of MeCl2, except MDI which requires 250 ml of 
MeCl2. Transfer a 5-ml aliquot of 1,2-pp (see Section 
7.3.8) to each solution, stir and allow to stand overnight at room 
temperature. Transfer 150 ml aliquots of hexane to each solution to 
precipitate the isocyanate-urea derivative. Using a Buchner funnel, 
vacuum filter the solid-isocyanate-urea derivative and wash with 50 
ml of hexane. Dissolve the precipitate in a minimum aliquot of 
MeCl2. Repeat the hexane precipitation and filtration 
twice. After the third filtration, dry the crystals at 50  deg.C and 
transfer to bottles for storage. The crystals are stable for at 
least 21 months when stored at room temperature in a closed 
    11.1.2  MI.  To prepare a 200 g/ml stock solution of 
methyl isocyanate-urea, transfer 60 mg of 1,2-pp to a 100-ml 
volumetric flask containing 50 ml of MeCl2. Carefully 
transfer 20 mg of methyl isocyanate to the volumetric flask and 
shake for 2 minutes. Dilute the solution to volume with 
MeCl2 and transfer to a bottle for storage. Methyl 
isocyanate does not produce a solid derivative and standards must be 
prepared from this stock solution.
    11.2  Concentration of Samples.
    11.2.1  Transfer each sample to a 1000-ml round bottom flask. 
Attach the flask to a rotary evaporator and gently evaporate to 
dryness under vacuum in a 65  deg.C water bath. Rinse the round 
bottom flask three times each with two ml of ACN and transfer the 
rinse to a 10-ml volumetric flask. Dilute the sample to volume with 
ACN and transfer to a 15-ml vial and seal with a Teflon 
lined lid. Store the vial at 4  deg.C until analysis.
    11.3  Preparation of Method Spikes.
    11.3.1  Prepare a method spike for every twenty samples. 
Transfer 300 ml of the absorption solution to a 1000-ml round bottom 
flask. Transfer 1 ml of a 100 g/ml standard containing the 
isocyanate-urea derivatives of interest. Follow the procedure 
outlined in Section 11.2.1 for sample concentration. This will 
result in a method spike with a theoretical concentration of 10 
    11.4  Preparation of Method Blanks.
    11.4.1  Prepare a method blank for every ten samples by 
transferring 300 ml of the absorption solution to a 1000-ml round 
bottom flask and concentrate as outlined in Section 11.2.1.
    11.5  Chromatographic Analysis.
    11.5.1  Chromatographic Conditions.

Column....................................   C18, 250 mm x 4.6 mm ID,   
                                             5m particle size. 
Mobile Phase..............................  Acetonitrile/Ammonium       
                                             Acetate Buffer.            
Gradient..................................  10:90 (v/v) ACN:AAB to 60:40
                                             (v/v) ACN:AAB over 30      
Flow Rate.................................  2 ml/min.                   
UV Detector...............................  254 nm.                     
Injection Volume..........................  50 l.              

    11.5.2  Analysis.  Analyze samples by HPLC, using conditions established 
in Section 11.5.1.  The width of the retention time window used to make 
identifications should be based upon measurements of actual 
retention time variations of standards over the course of a day.
    Three times the standard deviation of a retention time for a 
compound can be used to calculate a suggested window size; however, 
the experience of the analyst should weigh heavily in the 
interpretation of the chromatograms.  If the peak area exceeds the linear range of the 
calibration curve, the sample should be diluted with ACN and 
    12.0  Data Analysis and Calculations.
    Same as in Method 5, Section 6, with the following additions.
    12.1  Perform Calculations. Round off figures after the final 
calculation to the correct number of significant figures.
    12.2  Nomenclature. Same as Method 5, Section 6.1 with the 
following additions:
AS = Response of the sample, area counts.
b = Y-intercept of the linear regression line, area counts.
CI = Concentration of a specific isocyanate compound in 
the sample, g/ml.
M = Slope of the linear regression line, area counts-ml/g.
mI = Mass of isocyanate in the total sample.
VF = Final volume of concentrated sample, typically 10 

Vm(std) = Volume of gas sample measured by the dry-gas 
meter, corrected to standard conditions, dscm (dscf).

    12.3  Conversion from isocyanate to the isocyanate-urea 
derivative. The equation for converting the amount of free 
isocyanate to the corresponding amount of isocyanate-urea derivative 
is as follows:
    The equation for converting the amount of isocyanate-urea 
derivative to the corresponding amount of free isocyanate is as 

    12.4  Calculate the correlation coefficient, slope, and 
intercepts for the calibration data using the least squares method 
for linear regression. Concentrations are expressed as the x-
variable and response is expressed as the y-variable.
    12.5  Calculate the concentration of isocyanate in the sample:
    12.6  Calculate the total amount collected in the sample by 
multiplying the concentration (g/ml) times the final volume 
of ACN (10 ml).

    12.7  Calculate the concentration of isocyanate (g/
dscm) in the stack gas.


K = 35.31 ft3/m3 if Vm(std) is 
expressed in English units.
= 1.00 m3/m3 if Vm(std) is 
expressed in metric units.

    13.0  Method Performance.
    13.1  Method Performance Evaluation. Evaluation of analytical 
procedures for a selected series of compounds must include the 
sample-preparation procedures and each associated analytical 
determination. The analytical procedures should be challenged by the 
test compounds spiked at appropriate levels and carried through the 
    13.2  Method Detection Limit. The overall method detection 
limits (lower and upper) must be determined on a compound-by-

[[Page 64540]]

 compound basis because different compounds may exhibit different 
collection, retention, and extraction efficiencies as well as the 
instrumental minimum detection limit (MDL). The method detection 
limit must be quoted relative to a given sample volume. The upper 
limits for the method must be determined relative to compound 
retention volumes (breakthrough). Method Detection Limits may vary 
due to matrix effects and instrument conditions.
    13.3  Method Precision and Bias. The overall method precision 
and bias must be determined on a compound-by-compound basis at a 
given concentration level. The method precision value would include 
a combined variability due to sampling, sample preparation, and 
instrumental analysis. The method bias would be dependent upon the 
collection, retention, and extraction efficiency of the train 
components. From evaluation studies to date using a dynamic spiking 
system, acceptable method biases (per EPA Method 301) have been 
determined for all four isocyanates. A precision of less than 10% 
relative standard deviation (RSD) has been calculated from field 
test data sets which resulted from a series of paired, unspiked and 
spiked trains.
    14.0  Pollution Prevention. Not Applicable.
    15.0  Waste Management. Not Applicable.
    16.0  References.
    1. Martin, R.M., Construction Details of Isokinetic Source-
Sampling Equipment, Research Triangle Park, NC, U.S. Environmental 
Protection Agency, April 1971, PB-203 060/BE, APTD-0581, 35 pp.
    2. Rom, J.J., Maintenance, Calibration, and Operation of 
Isokinetic Source Sampling Equipment, Research Triangle Park, NC, 
U.S. Environmental Protection Agency, March 1972, PB-209 022/BE, 
APTD-0576, 39 pp.
    3. Schlickenrieder, L.M., Adams, J.W., and Thrun, K.E., Modified 
Method 5 Train and Source Assessment Sampling System: Operator's 
Manual, U.S. Environmental Protection Agency, EPA/600/8-85/003 
    4. Shigehara, R.T., Adjustments in the EPA Nomograph for 
Different Pitot Tube Coefficients and Dry Molecular Weights, Stack 
Sampling News, 2:4-11 (October 1974).
    5. U.S. Environmental Protection Agency, 40 CFR Part 60, 
Appendix A, Methods 1-5.
    6. Vollaro, R.F., A Survey of Commercially Available 
Instrumentation for the Measurement of Low-Range Gas Velocities, 
Research Triangle Park, NC, U.S. Environmental Protection Agency, 
Emissions Measurement Branch, November 1976 (unpublished paper).
    17.0  Tables, Diagrams, Flowcharts, and Validation Data.

 Table 1.--Molecular Weight of the Free Isocyanates and the Isocyanate- 
                             Urea Derivative                            
                                                 MW (free        MW     
                   Analyte                     Isocyanate)  (Derivative)
1,6-HDI......................................       168          494.44 
2,4-TD.......................................       174.16       500.56 
MDI..........................................       250.25       576.65 

     Table 2.--Molecular Weight of Free Methyl Isocyanate and Methyl    
                       Isocyanate-Urea Derivative                       
                                                 MW (free        MW     
                   Analyte                     Isocyanate)  (Derivative)
MI...........................................        57.1        220.32 

            Table 3.--Retention Times of the Four Isocyanates           
                           Compound                               time  
MI...........................................................       10.0
1,6-HDI......................................................       19.9
2,4-TDI......................................................       27.1
MDI..........................................................       27.3


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[FR Doc. 97-32045 Filed 12-5-97; 8:45 am]