[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]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 51
[FRL-5930-6]
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.
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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,
1998.
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.
20460.
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.
SUPPLEMENTARY INFORMATION:
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
significant.''
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
entities.
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,
Administrator.
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
Emissions.
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
evaluated:
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Detection
Compound name CAS No. limits a Manufacturing process
(ng/m\3\)
----------------------------------------------------------------------------------------------------------------
2,4-Toluene Diisocyanate (TDI)...... 584-8 106 Flexible Foam Production.
4-9
1,6-Hexamethylene Diisocyanate (HDI) 822-0 396 Paint Spray Booth.
6-0
Methylene Diphenyl Diisocyanate 101-6 112 Pressed Board Production.
(MDI). 8-8
Methyl Isocyanate (MI).............. 624-8 228 Not used in production.
3-9
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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.
6.1.3.1 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.
6.1.3.2 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.
6.1.3.3 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.
6.1.3.4 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.
6.1.3.5 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.
6.1.3.6 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.
6.1.3.7 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).
6.1.3.8 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.
6.1.3.9 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
temperature.
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
used.
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
evaporator.
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
times.
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
preparation.
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,="">6H5CH3. HPLC
Grade or equivalent.
7.3.2 Acetonitrile, CH3CN (ACN). HPLC Grade or
equivalent.
7.3.3 Methylene Chloride, CH2CL2. HPLC
Grade or equivalent.
7.3.4 Hexane, C6H14. Pesticide Grade or
equivalent.
7.3.5 Water, H2O. HPLC Grade or equivalent.
7.3.6 Ammonium Acetate,
CH3CO2NH4.
7.3.7 Acetic Acid (glacial), CH3CO2H.
7.3.8 1-(2-Pyridyl) piperazine, (1,2-pp). Aldrich, 99.5+% or
equivalent.
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
stack.
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=""> 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.
8.4.1.1 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.
8.4.1.2 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.
8.4.1.3 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.
8.4.1.4 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.
8.4.2.1 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.
8.4.2.2 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.
8.4.3.1 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
closed.
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
material.
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.
8.6.1.1 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.
8.6.1.2 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.
8.6.1.3 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.
8.6.1.4 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.
8.6.1.5 Inspect the train prior to and during disassembly and
note any abnormal conditions.
8.6.2 Sample Containers.
8.6.2.1 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.
8.6.2.2 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
control.
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
used.
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
thermometer.
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
derivatized
[[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.
11.1.1.1 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
container.
11.1.2 MI.
11.1.2.1 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
g/ml.
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
minutes.
Flow Rate................................. 2 ml/min.
UV Detector............................... 254 nm.
Injection Volume.......................... 50 l.
11.5.2 Analysis.
11.5.2.1 Analyze samples by HPLC, using conditions established
in Section 11.5.1.
11.5.2.2 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.
11.5.2.3 If the peak area exceeds the linear range of the
calibration curve, the sample should be diluted with ACN and
reanalyzed.
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
ml.
[GRAPHIC] [TIFF OMITTED] TP08DE97.006
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
follows:
[GRAPHIC] [TIFF OMITTED] TP08DE97.007
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:
[GRAPHIC] [TIFF OMITTED] TP08DE97.008
12.6 Calculate the total amount collected in the sample by
multiplying the concentration (g/ml) times the final volume
of ACN (10 ml).
[GRAPHIC] [TIFF OMITTED] TP08DE97.009
12.7 Calculate the concentration of isocyanate (g/
dscm) in the stack gas.
[GRAPHIC] [TIFF OMITTED] TP08DE97.010
Where:
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
procedures.
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
(1985).
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
------------------------------------------------------------------------
Retention
Compound time
(minutes)
------------------------------------------------------------------------
MI........................................................... 10.0
1,6-HDI...................................................... 19.9
2,4-TDI...................................................... 27.1
MDI.......................................................... 27.3
------------------------------------------------------------------------
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