EPA-600/2-76-124
May 1976
Environmental Protection Technology Series
SAMPLING OF AUTOMOBILE INTERIORS FOR
VINYL CHLORIDE MONOMER
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3! Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the
views and policy of the Agency, nor does mention of trade
names or commercial products constitute endorsement or
recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-124
May 1976
SAMPLING
OF AUTOMOBILE INTERIORS
FOR VINYL CHLORIDE MONOMER
by
William H. Hedley, Joseph T. Cheng
Robert J. McCormick, and Woodrow A. Lewis
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
Contract No. 68-02-1404, Task 1 (Change 2)
ROAPNo. 21AXM-073
Program Element No. 1AB015
EPA Project Officer: David K. Oestreich
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
The report gives results of a study to qualitatively identify or-
ganic pollutants in the air inside new automobiles. In recent
years, concern has developed over the concentration of organic
vapors inside new automobiles. A literature search first identi-
fied numerous volatilization products from plastics used in the
construction of automobile interiors. Charcoal tubes were used
to collect air samples in seven test vehicles. The concentrations
in the other five test vehicles during this preliminary study were
below the detection limit of 0.05 ppm.
11
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Abstract
Figures
Tables
CONTENTS
Page
ii
iv
iv
I Introduction
II Summary and Conclusions
III Literature Survey
A. Volatilization products of plastics
B. Suspected carcinogenic compounds
IV Sampling Procedures
A. Automobiles Sctmpled
B. Sample collection
V Sample Analysis
VI Results and Discussion
1
2
3
3
11
12
12
12
15
17
References
Appendices
20
A. Data sheets 22
B. Sampling and analysis of vinyl chloride in air 26
111
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Number
FIGURES
Charcoal tube used to collect VCM sample
Page
13
TABLES
Number Page
1 Summary of Uses of Plastics in Automobile
Interiors 4
2 ABS Volatilization Products 5
3 Volatilization Products of Plex 55 Acrylic 5
4 Volatilization Products from Epoxy Adhesives 6
5 Volatilization Products from Two Melamine Samples 7
6 Volatilization Products of Phenolic Compounds 7
7 Volatilization Products from Two Polyester/Glass 8
Reinforced Samples
8 Volatilization Products from Polypropylene 65-23 8
9 Volatilization Products from Polyurethanes 9
10 Volatilization Products from PVC 10
11 Volatilization Products from Plastics Used in
the Interior of 1975 Automobiles 11
12 VCM in the Interior of 1975 Automobiles 18
IV
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SECTION I
INTRODUCTION
In recent years, some concern has developed over the concentra-
tions of organic vapors in the interior of new automobiles. The
principal sources of these organic pollutants are the plastics,
rubbers, and adhesives that are extensively used in the interior
of automobiles. The major volatilization products are unreacted
monomers, plasticizers, and solvents trapped in the polymer
during manufacture. The concentration of these compounds which
are volatilized could exceed OSHA limits.
The purpose of this study was to obtain preliminary measurements
of the concentration of vinyl chloride monomer (VCM) in the air
in the interior of new automobiles. A literature search was also
conducted to determine the expected volatilization products from
plastics used in the construction of new automobile interiors.
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SECTION II
SUMMARY AND CONCLUSIONS
Preliminary measurements were made of the vinyl chloride monomer
(VCM) concentration in the interiors of seven different new 1975
automobiles. These were: Ford Pinto, Dodge Dart Sport, American
Motors Gremlin, Volkswagen Rabbit, General Motors Vega, General
Motors Chevrolet, and a Datsun 710. These compact and subcompact
cars were selected because their ratio of plastic to interior
volume was high and would be expected to result in worst-case con-
centrations' for VCM.
Charcoal tubes were used to collect samples for VCM analysis.
After drawing a known volume of air through each tube, the tubes
were transported back to the laboratory for analysis by the NIOSH
carbon disulfide extraction/gas chromatographic detection method.
Of the seven cars tested, only two, the Ford Pinto and the Dodge
Dart, had measurable amounts of VCM in the interior atmospheres.
These concentrations ranged from 0.4 ppm to 1.2 ppm. In the
other five cars, the VCM concentrations were below the detection
limit of the analytical system, 0.05 ppm.
These data indicate that concentrations of vinyl chloride monomer
inside new cars rarely exceed the recommended exposure limit of
one ppm, even in cases where the cars have received little or no
ventilation. Calculation of the maximum one-time exposure to VCM
in 1975 cars would not be expected to exceed 30 ppm, even assuming
zero loss of VCM from the polyvinylchloride from its time of manu-
facture until the time when it was all released inside the un-
ventilated car.
Volatilization of organic compounds from plastics used to construct
automobile interiors was studied. A literature search was also
conducted to determine the potential volatilization products from
nineteen plastic and adhesive products typically used in automo-
bile interiors. A total of 41 organic gases which volatilize
from these products at temperatures of 25°C or 68°C were identi-
fied, ranging from methane to alcohols to linear phthalate esters.
Six of the compounds identified are listed as suspected carcinogens;
vinyl chloride, trichloroethylene, benzene, phenol, chloroform, and
1,4-dioxane.
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SECTION III
LITERATURE SURVEY
A. VOLATILIZATION PRODUCTS OF PLASTICS
A literature survey was conducted to determine the potential
volatilization products from the plastics used to construct the
interiors of new automobiles. The majority of the plastics used
for automobile interiors include ABS (acrylonitrile-butadiene-
styrene), acrylic, polyethylene, polypropylene, polyurethane, and
PVC (polyvinyl chloride). Plastics that are used in lesser
quantities include alkyds, cellulosics, epoxies, fluoroplastics,
melamine, noryl phenylene oxide-based resin, nylon, phenolic,
polycarbonate, reinforced polyeister, polystyrene, SAN (styrene-
acrylonitrile), and thermoplastic polyester. The uses of these
plastics are summarized in Table 1.
The volatilization products associated with these plastics were
determined in a series of studies conducted by Pustinger, Hodgson,
and co-workers of Monsanto Research Corporation.1"5 In these
studies, the off-gas products of a number of specific plastics
compounds were measured at 25°C and 68°C. For the purpose of
this report, no attempt was made to quantify these emissions
because of varying sampling and analytical techniques used. A
brief discussion of the off-gas products from specific plastic
compounds is given below.
1. Aerylonitrile-Butadiene-Styrene (ABS)
In automobile interior construction, ABS finds extensive applica-
tion in dashboard and instrument panel components and is used in
conjunction with other plastics in seat assemblies, door and
quarter panels, armrest assemblies, seat belts, plated hardware,
vents and ducts, and as a structural base for assorted trim.
In an analysis of one type of commercial ABS polymer (Boltaron)
eight volatilization products were identified at 25°C and six
products at 68°C (Table 2). In both cases unreacted styrene
monomer was the principal constituent.
In a study conducted by Harrison and Portwood,6 various ABS
materials were heated at temperatures of 49-90°C. Again styrene
was the principal volatilization product, representing 95% (by
weight) of the organics released.
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TABLE 1. SUMMARY OF USES OF PLASTICS IN AUTOMOBILE INTERIORS
Plastics
Use
ABS (acrylonitrile-
butadiene-styrene)
Acrylic
Epoxy
Phenolic
Polyester/glass
Polypropylene
Polyurethane
Dashboard, instrument panel components, seat assembly, door
and quarter panels, armrest assemblies, seat belts, plated
hardware, vents and ducts, structural base for assorted
trim
Nameplates, dials, various instrument panel components
Adhesive for numerous components
Small quantity used as a sealant and adhesive
Heater and air conditioning housing
Door panels, heater and air conditioning housing, station
wagon decks, seat backs, dash panel inserts, sun visor,
filler panels and other trim
Cushioning material, trim, horn buttons, armrests, sun
visor, crash pads
PVC (polyvinyl chloride)
Seat padding, seat upholstery, head liners, crash pad, sun
visor, armrests
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TABLE 2. ABS VOLATILIZATION PRODUCTS
At 25°C At 68°C
Methane Methane
Trichloroethylerie Trichloroethylene
Ethanol Toluene
n-Propanol Xylene
Toluene Styrene
Xylene Methylstyrene
Styrene
Methylstyrene
2. Acrylic
Acrylic plastics are used for nameplates, dials, and various
other instrument panel components.
In an analysis of Plex 55 acrylic, only one volatilization
product, methane, was identified at 25°C. At 68°C, three off-gas
products were detected (Table 3). In both cases only low concen-
trations of volatiles were noted.
TABLE 3. VOLATILIZATION PRODUCTS OF PLEX 55 ACRYLIC
At 25°C At 68°C
Methane Methane
n-Propanol
Benzene
3. Epoxy
Epoxy resin adhesives are used throughout the interior of auto-
mobiles.
The literature yielded information on eight types of epoxy ad-
hesives that have been tested for volatilization products. The
results of these analyses vary widely. Several of the adhesive
compositions had as many as nine off-gas products, while one of
the compounds, epoxy Stycase 2651/catalyst II, was free of vola-
tilization products.
Although the results from these analyses were difficult to
quantify, the predominant volcitilization products at 25°C were
methane, ethanol, and xylene. In at least two of the compounds
tested, xylene was detected in high concentrations. At 68°C the
most common off-gas products were methane, ethanol, xylene, and
acetone. A list of all possible volatilization products from
epoxy adhesives is given in Table 4.
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TABLE 4. VOLATILIZATION PRODUCTS FROM EPOXY ADHESIVES
At 25°C
At 68°C
(5) Methane
(1) 1,1,1-Trichloroethane
(1) Trimethylhexane
(1) Ethylene
(1) Methanol
(4) Ethanol
(3) n-Propanol
(1) Isopropanol
(1) 2-Methyl-l-propanol
(2) n-Butanol
(1) Diethyl ether
(3) Acetone
(3) 2-Butanone
(1) 4-Methyl-2-pentanone
(1) 2-Methyl-4-pentanone
(3) Toluene
(4) Xylene
(5) Methane
(1) 1,1,1-Trichloroethane
(2) dij-Cg Hydrocarbons
(1) Ethylene
(1) Methanol
(5) Ethanol
(2) n-Propanol
(1) Isopropanol
(1) 2-Methyl-l-propanol
(2) n-Butanol
(1) Diethyl ether
(4) Acetone
(3) 2-Butanone
(1) 4-Methyl-2-pentanone
(1) 2-Methyl-4-pentanone
(3) Toluene
(4) Xylene
(1) Benzaldehyde
Number in parentheses denotes the number of epoxy com-
pounds tested (out of a total of 8) which produced this
volatilization product.
4. Melamine
Approximately twenty alcohols and aliphatic and aromatic hydro-
carbons were identified as the volatilization products from two
melamine compounds. The major off-gas compound at both temperatures
was n-butanol, while xylene was also present in high concentrations
at 25°C (Table 5).
5. Phenolic
In the construction of automobile interiors, phenolic resin is used
in small quantities as a sealant and adhesive.
Volatilization products from three commercial phenolic compounds
ranged from a mixture of seven aliphatic and aromatic hydrocarbons
and ketones to methane alone (Table 6). The same volatiles were
identified at 25°C and 68°C with the exception of methane, which
was not detected at 25°C.
6.
Polyester/Glass
Glass-reinforced polyesters are used in automobile interiors for
heater and air conditioner housings.
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TABLE 5. VOLATILIZATION PRODUCTS FROM TWO MELAMINE'SAMPLES
At 25° C
At 68°C
(2) Methane
(1) C^-Cg Hydrocarbons
(2) C7-C8 Hydrocarbons
(1) Cg-C}0Hydrocarbons
(2) Ethanol
(2) n-Propanol
(1) 2-Propanol
(1) 2-Methyl-l-propanol
(2) n-Butanol
(1) Benzene
(1) Toluene
(1) GS-CS Alkylbenzene
(2) Xylene
(1) Higher molecular weight
alkylbenzenes
(1) Methane
(2) C^-Cg Hydrocarbons
(2) CJ-CQ Hydrocarbons
(1) C10 Hydrocarbons
(2) Ethanol
(2) n-Propanol
(1) 2-Propanol
(1) 2-Methyl-l-propanol
(2) n-Butanol
(1) Toluene
(2) Xylene
(1) C3-C5 Alkylbenzene
(1) Higher molecular weight
alkylbenzenes
TABLE 6. VOLATILIZATION PRODUCTS OF PHENOLIC COMPOUNDS
At 2S°C and 68°C
(2)a Methane
(1) C6-C7 Hydrocarbons
(1) n-Propanol
(1) Furfuraldehyde
(1) Acetone
(1) Methyl ethyl ketone
(1) Benzene
(2) Toluene
(2) Xylene
(1) Phenol
Number in parentheses
denotes the number of
phenolic compounds tested
(out of a. total of 3)
which produced this vola-
tilization product.
The volatilization products were identified in an analysis of two
reinforced polyester products are listed in Table 7. Only small
concentrations of acetone, benzene, and xylene were detected in
off-gas products from both samples.
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TABLE 7. VOLATILIZATION PRODUCTS FROM TWO POLYESTER/GLASS
REINFORCED SAMPLES
At 25°C At 68°C
C7-Saturated hydrocarbons Methane
2-Propanol Cy-Saturated hydrocarbons
2-Methyl-2-propanol n-Propanol
2-Butanol 2-Propanol
Acetone 2-Methyl-2-Propanol
Benzene n-Butanol
Toluene 2-Butanol
Xylene Benzene
Toluene
Xylene
Cif-Alkylbenzene
7 . Polypropylene
In authomobile interiors, reinforced polypropylene foam is used
in quarter and door panels, heater and air conditioning housings,
station wagon decks, seat backs, dash panel inserts, sun visors,
filler panels, and miscellaneous trim. For many such applica-
tions, polypropylene is copolymerized with ethylene.
Emissions of volatilization products are reduced because unreacted
propylene monomer, amorphous polymer, and reaction diluents are
removed from the polypropylene during processing. Five vola-
tilization products of Polypropylene 65-23 were identified (Table
8) . With the exception of toluene, all of these volatile com-
pounds were C^-Cg alkenes and were found in low concentrations.
Emission species were quantitatively identical at both 25°C and
68°C.
Table 8. VOLATILIZATION PRODUCTS FROM
POLYPROPYLENE 65-23
At 25°C and 68°C
Butene
Methyl butene
Dimethyl butene
Trimethyl hexadiene
Toluene
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8. Polyurethane
Flexible and rigid polyurethane foams and all types of integral-
skin foams are the most widely used plastics in automobile in-
teriors. Flexible and rigid foams account for nearly all cushion-
ing materials, while integral-skin polyurethanes are widely used
in the trim. Flexible foams are used for horn buttons, armrests,
and sun visors. Semirigid foams are used for crash pads.
Since so many different combinations of compounds are used in
polyurethane formulations, volatile emissions vary considerably
from one product to another. A total of fifteen volatilization
products have been detected in the off-gas products from seven
commercial polyurethane compounds (Table 9). At 25°C, ten dif-
ferent volatilization products were identified, but only methane,
ethanol, n-butanol, toluene, and xylene were present in two or
more polyurethane samples. At 68°C, only methane, ethanol,
toluene, and xylene were emitted by more than one of the samples.
Two of the polyurethanes tested, Spandex Lycra Polyurethane and
Polyurethane PR 15-35, were free of volatiles.
TABLE 9. VOLATILIZATION PRODUCTS FROM POLYURETHANES
At 25°C
At 68°C
(4) Methanol
(3) Ethanol
(2) n-Butanol
(1) Acetone
(1) Benzene
(4) Toluene
(3) Xylene
(1) CI-GS Alkylbenzenes
(2) 2-Phenyl-2-propanol
(1) Acetophenone
(3) Methane .
(1) Chloroform
(1) Methanol
(2) Ethanol
(1) n-Butanol
(1) 2-Methyl-2-butanol
(1) Acetone
(1) Benzene
(3) Toluene
(2) Xylene
(1) Cj-Cs Alkylbenzenes
(1) 2-Phenyl-2-propanol
(1) Acetophenone
(1) 1,4-Dioxane
(1) n-Methyl morpholine
Number in parentheses denotes the number of polyurethane
compounds tested (out of a total of 7) which produced
this volatilization product.
Possibly carcinogenic.
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9. Polyvinyl Chloride (PVC)
In thQ construction of automobile interiors, PVC sheet and foam
find a wide variety of applications; they are second only to the
polyurethanes in total consumption. PVC foam is used primarily
for seat padding and undercovering, and PVC sheet is used for
seat upholstering, head liners, crash pad skin, and facing for
rear window panels, door inner panels, sun visors, and armrests.
An analysis of Boltaron 6200, Rigid PVC Type I for volatiles de-
tected only three hydrocarbons at 68°C, and none at 25°C. How-
ever, it is suspected that unreacted vinyl chloride monomer may
be a volatilization product of the plasticized PVC found in
automobile interiors. It has been estimated7 that vinyl chloride
levels in PVC resins may range as high as 8000 ppm, although
unreacted monomer concentrations are usually in the neighborhood
of 50-1000 ppm. In finished products, this figure is probably
reduced to 5-20 ppm.
Plasticizer volatilization is a recognized attribute of PVC
products, and has been cited as the major cause of windshield
fogging and "new car smell."8 In automobile interior components,
the linear phthalates are the most commonly used plasticizers,
possessing better low-temperature properties than the more uni-
versally popular branched phthalates. Linear phthalate esters
are based on linear C6-C10 alcohols, and normally comprise 15-50%
of a PVC product.
Phthalate ester concentrations on the order of 0.3 yg/liter have
been measured in automobile interiors. However, this testing was
conducted on a 1972 automobile and it is not known whether
branched or linear phthalate plasticizers were involved. The
linear phthalates are known to be 50-80% less volatile than their
branched counterparts.
TABLE 10. VOLATILIZATION PRODUCTS FROM PVC
At 25°C
At 68°C
Vinyl chloride
Linear phthalate esters
Methane
C1+ -C 5 Hydrocarbon
Vinyl chloride
Toluene
Linear phthalate esters
10. Polystyrene and Styrene-Acrylonitrile (SAN)
Although no information was available on the volatilization
products of polystyrene and styrene-acrylonitrile, data from ABS
10
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materials suggest the possibility of unreacted styrene monomer
volatilization.
11. Nylon, Polycarbonate, and Polyethylene
Tests conducted on polyethylene film and various nylon and
polycarbonate products indicate that these materials are free of
volatiles.
12. Alkyds, Cellulosics, Fluoroplasticsy NORYL Phenylene-Oxide-
Based Resin/ and Thermoplastic Polyester
No information was found dealing with the ambient volatilization
products of these materials. However, these compounds find very
limited application in automobile interiors and probably do not
contribute significantly to organic pollutant levels.
B. SUSPECTED CARCINOGENIC COMPOUNDS
One of the objectives of this project was to identify those
volatilization products that are suspected carcinogens. Table 11
lists all volatilization products identified in the previous
section with the suspected carcinogen compounds identified.9
TABLE 11. VOLATILIZATION PRODUCTS FROM PLASTICS USED IN
THE INTERIOR OF 1975 AUTOMOBILES
Volatilization products at 25°C and 68°C
Methane Diethyl ether
Trichloroethane Furfuraldehyde
Trimethylhexane Acetone
Ck-C1Q Hydrocarbons Methyl ethyl ketone
Ethylene a 2-Butanone
Vinyl chloride g 4-Methyl-2-pentanone
Trichloroethylene 2-Methyl-4-pentanone
Butene Benzene3
Methylbutene Toluene
Dimethylbutene Xylene
Trimethylhexadiene Styrene
Methanol Methylstyrene
Ethanol Ci-Cs Alkylbenzenes
2-Propanol Higher MW alkylbenzenes
2-Methyl-2-propanol 2-Phenyl-2-propanol
n-Butanol Acetophenone
2-Butanol Linear phthaltate esters
Additional products at 68°C
Chloroform3 Benzaldehyde
1,1,1-Trichloroethane if4-Dioxanea
2-Methyl-2-butenal
Suspected carcinogenic compounds9
11
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SECTION IV
SAMPLING PROCEDURES
A. AUTOMOBILES SAMPLED
Arrangements were made with various automobile dealers in Dayton,
Ohio to sample new 1975 model vehicles for vinyl chloride monomer
(VCM). The test vehicles were selected to insure a broad spec-
trum of vehicle types and manufacturers were sampled. Subcompact
and compact cars were tested because the ratio of plastic to
interior volume was high and would result in a worst-case organic
concentrations.
The seven 1975 automobiles selected for the test were a Ford
Pinto, Dodge Dart Sport, American Motors Gremlin, Volkswagen
Rabbit (Hatchback), General Motors Vega, General Motors Chevrolet
(Station Wagon), and a Datsun 710. A description of each auto-
mobile tested is included in the data sheets in Appendix A. Each
data sheet describes the interior and exterior colors of the
vehicle as well as the date the vehicle was assembled and the
data the samples were taken.
B. SAMPLE COLLECTION
In order to quantitatively sample for VCM charcoal tubes were
used for collection.
Charcoal tubes purchased from SKC, Inc. (Pittsburgh, Pa.) (Figure
1) were used to collect VCM in the interior of each test auto-
mobile. Each glass collection tube was filled with 100 mg of
charcoal. Tests were performed by drawing 3 liters of air
through the tube at 50 ml/min. The tubes were then capped,
stored in a freezer at -20°C, and transported to the laboratory
for VCM analysis by an extraction/gas chromatographic technique.
Sampling runs were made with personal-type air samplers. Two
electric Telmatic Air Samplers (Bendix Models 150 and C115) were
modified with remote controls so they could be activated from
outside of the test vehicle. The batteries used to power the
pumps were also located outside of the vehicle. Each sampling
pump was calibrated and adjusted for a constant flow rate of
50 ml/min. The sampling tubes were placed on the front seat next
to the sampling pump and connected by short tubes to minimize the
exposure of the sample to tubing materials before the gases got
to the carbon sorbent.
12
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OJ
N.I.O.S.H. APPROVED SEALING CAPS
SEAL TUBE WITHOUT SAMPLE CONTAMINATION
GLASS WOOL
FOAM SEPARATOR
OF UNIFORM POROSITY
PRECISION LOCK-SPRING
HOLDS CHARCOAL LAYERS IN PLACE
THUS PREVENTING SAMPLE CHANNELING
SAMPLE LAYER
100mg. OF CHARCOAL
BACK-UP CHARCOAL LAYER, 50mg.
TIP PRECISION SEALED
FOR SAFE AND EASY BREAKING
TO DESIRED OPENING SIZE
PATENT PEN DING
Figure 1. Charcoal tube used to collect VCM sample.
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Each sampling package was equipped with a thermistor to measure
the air temperature inside the test vehicle. An additional
thermistor was used to measure the ambient temperature outside of
the automobile.
The sample collection package was placed on the front seat,
either on the driver's side or the passenger's side, wherever it
appeared that the sun would heat the seat the most. It was
reasoned that sampling the hottest seat during the hot summer
time should establish a worst-case condition for pollutant con-
centrations. After placing the sampling package and inserting
the collection tubes, the control wires for the samples were then
run through the window, which was quickly rolled up to the top
position. The seal at the top of the window was such that the
window could be tightly closed and still allow the wires to pass
through.
A period of at least 30 minutes was allowed to pass before sampling
began in order to help reestablish equilibrium inside the car.
Being aware that this time might not be sufficient to reach
equilibrium, every effort was made to open the door carefully,
slide the sampler in quickly, and close the door with minimum air
interchange. This was always done from the downwind side to
minimize ventillation in the car during this time. Unless over
one-half of the air was changed during the sampler placement, the
concentration read should be at least one-half of the maximum
level, even if no additional vinyl chloride diffused out into the
air space during the one-half hour waiting period before sampling.
The actual amount of air interchange would be expected to be con-
siderably less than this.
The sampling pumps were activated until approximately 3 liters of
air had been sampled. The pumps were then turned off, and the
collection tubes were quickly prepared for storage as previously
described. The sampling conditions and the temperature of the
seat, interior air, and exterior air are also shown on the data
sheets in Appendix A.
14
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SECTION V
SAMPLE ANALYSIS
The charcoal tubes were analyzed for VCM according to the tech-
nique described by the National Institute of Occupational Safety
and Health (NIOSH), Method No. 178.10 This procedure is given in
Appendix B. Briefly, this method describes a procedure for
determining quantitatively the amount of vinyl chloride in air by
adsorption on charcoal and subsequent analysis by carbon disul-
fide extraction and gas chromatographic detection. This method
also describes a procedure for determining the desorption ef-
ficiency of VCM from the charcoal by carbon disulfide extraction.
To determine the desorption efficiency, a standard solution of
VCM and carbon disulfide was first prepared. A known concentra-
tion of 99.9% pure VCM was dissolved in a known volume of carbon
disulfide as described in the Volumetric Method, Section 9.1 of
NIOSH Method No. 178.10 Various volumes of this solution were
injected into a gas chromatograph equipped with a flame ioniza-
tion detector and the response was recorded. A standard curve
was prepared by plotting the known quantity of VCM versus the
peak area recorded from the gas chromatograph response.
Next, a known concentration of VCM vapor was injected with a gas-
tight syringe into a Tedlar* bag filled with a known volume of
air. A charcoal tube was then attached to the bag outlet and a
known volume of this air-VCM mixture was drawn through the char-
coal tube. By using the air temperature and pressure, volume of
air sampled, and VCM concentration in the Tedlar bag, the quantity
of VCM absorbed by the charcoal tube could be calculated.
The charcoal was then extracted with carbon disulfide as described
in NIOSH Method No. 178. 10 Known volumes of the extract were
injected into the gas chromatograph and the response recorded.
The peak areas obtained from these samples were compared to the
standard curve to determine the quantity of VCM in the sample.
The desorption efficiency was determined by dividing the quantity
of VCM measured from the extract by the quantity of VCM calcu-
lated to be adsorbed in the charcoal tubes.
The desorption efficiency was measured three times using three
concentrations of standard VCM gases. The standard gases had VCM
*Fluorodynamics, Inc., Newark, Delaware.
15
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concentrations of 1 ± 0.1 ppm, 10 ± 0.5 ppm, and 50+1 ppm.
These mixtures were purchased and certified by MG Scientific
(Kearny, N.J.). For the batch of charcoal tubes used throughout
this study, the desorption efficiency of VCM from the charcoal
was determined by carbon disulfide extraction to be 31%, 31%,
and 30% — for an average of 31% — and showed very good repro-
ducibility. Though this percentage is not high similar measure-
ments by other investigators have obtained readings of 18% for
this measurement. Factors such as polymerization of VCM on the
carbon and adsorption on vessel walls are suspected as being the
primary causes for low desorption efficiencies when dealing with
small amounts of VCM. These measurements were done at room
temperature since the sample analyses were also done at these
same conditions.
The minimum detectable limit for this gas chromatographic system
for vinyl chloride was 0.75 ng per 5 yl injection. This resulted
in a minimum atmospheric detection limit of 0.05 ppm for the
sampling technique previously described.
The charcoal in the sampling tubes was divided into two parts
(see Figure 1). The front half of the tube contained approxi-
mately 2/3 of the charcoal, while the back half contained the
rest. After having a gas sample containing 500 micrograms of VCM
passed through the tube, analysis of the back half of the tube
revealed no VCM, meaning that the front half of the tube was
100% efficient at 23°C.
The question as to expected adsorption efficiency at higher
temperatures might be raised. The actual sorption temperatures
inside the cars ranged from 43°C to 66°C. To check the sorption
efficiency of the carbon at the higher temperatures, the ratio of
the equilibrium static absorptive capacity per unit weight of
carbon at 65°C as compared to that at 25°C was calculated using
the method recommended by Nelson and Harder.11 This calculation
indicates that the equilibrium static sorptive capacity for carbon
at 65°C should be 18 percent as great as it is at 25°C. This is
definitely more than adequate since the carbon in the first half
of the tube completely adsorbed 500 micrograms of VCM during the
test at 25°C and the three liter sample containing 1.2 ppm of
VCM taken at elevated temperature contained only 2.6 micrograms
of this material.
The gas chromatograph was equipped with a flame ionization
detector and a 1.83 m x 0.21 cm column, packed with 80-100 mesh
Chromosorb 102. A nitrogen carrier gas was used with a flow rate
of approximately 30 ml/min.
Hydrogen (at 10 psig) was flowed at 25 ml/min and air (at 20
psig) was flowed at 110 ml/min to the flame ionization detector.
The syringe injector port was maintained at 129°C, the oven at
127°C, and the detector at 119°C.
16
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SECTION VI
RESULTS AND DISCUSSION
The results of the analyses of the charcoal tubes are shown in
Table 12. The table indicates the make and model of the auto-
mobile tested, the temperature of the ambient air, interior air
and seat surface, the number of days between the vehicle assembly
and sampling dates, and the concentration of VCM detected. If
VCM was not detected, then the VCM concentration was below the
minimum detection limit of 0.05 ppm for the analytical system.
VCM was detected in only two of the seven automobiles tested, the
Ford Pinto and the Dodge Dart. The higher concentration of VCM
(1.2 ppm) found in the Ford Pinto may be due to a combination of
the higher seat surface temperature (66°C) compared to the other
vehicles tested and the relatively shorter period of time between
vehicle assembly and sampling dates.
The concentration of VCM in the interior of a new automobile may
be dependent on how frequently the vehicle is ventilated. Since
it was not possible to control or quantify this variable, this
could explain why VCM was detected in the Dodge Dart and not in
the other five vehicles of comparable age. This conclusion is
based on the assumption that the ratio of the vehicle interior
volume to the quantity of polyvinyl chloride plastic is the same
in each test vehicle. Data were not available to substantiate
this assumption.
Since the level of VCM in 5 out of 7 of the test vehicles was
below the detection limits of the analytical system, it was not
possible to quantitatively develop a relationship between VCM
volatilization emissions and the temperature of the seats or the
age of the test vehicle. It also appeared that the interior and
exterior colors of the automobile had no effect on the VCM emis-
sions. The Ford Pinto had a black interior, but the Dodge Dart
had a white interior. The darker interiors did, as expected,
result in higher seat temperaitures than did the lighter colored
interiors.
The temperature to which the PVC plastic in the car is exposed
should affect the rate at which VCM is emitted and the concen-
tration level measured. A comparison of the seat temperatures
and the VCM levels recorded in Table 12 does not show any cor-
relation since all five of the cars with no measurable VCM con-
centration had higher seat temperatures than the Dodge Dart did.
17
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Table 12. VCM IN THE INTERIOR OF 1975 AUTOMOBILES
CO
Temperature ,
1975 Automobile sampled
Ford Pinto
Dodge Dart: Front seat
Back seat
American Motors Gremlin
Volkswagen Rabbit
(Hatchback)
General Motors Vega
General Motors Chevrolet
(Station wagon)
Datsun 710
Ambient
air
36
27
27
33
31
33
33
30
Interior
air
60
50
50
44
43
45
45
43
°C
Seat
surface
66
46
46
52
55
49
49
50
Number of
days since
vehicle
assembly
32
102
102
>60
70
>30
120
60
' Vehicle color „
Exterior
Drk. red
Drk. red
Dr. Grn.
Red
Lt. blue
Lt. brn.
Drk. red
Interior
Black
White
Drk . Grn .
Black
Lt. blue
Black
White
VCM
oncentration,
ppm
1.2
0.4
0.7
<0.05a
<0.05
<0.05
<0.05
<0.05
Minimum detectable limit of the analytical system.
-------
PVC is a very stable material. Even when it does slowly decompose
with age, it does not form more VCM. Hence the only VCM in the
PVC in cars is that which was originally unreacted.
As the literature search revealed, the quantity of unreacted VCM
remaining in a finished product constructed of PVC ranges from 5-
20 ppm. An average automobile contains about 25 pounds of PVC.
Therefore, the quantity of VCM trapped in the plastic would com-
monly be expected to range from 55 to 225 rag. If all of the VCM
were volatilized at once into an automobile with 3 cubic meters
of air space, this would result in VCM concentrations ranging
from 7.2 to 29 ppm.
In conclusion, the data obtained in this study indicate that VCM
concentrations in 1975 automobile interiors were in most cases
below the recommended NIOSH standard of one ppm even in cars
which were unventilated. With ventilation any car which contained
a significant concentration, such as 1 ppm, would lose its VCM
rather rapidly since the car would not be expected (by material
balance) to be able to reestablish this concentration more than
7 to 29 times.
It should also be mentioned, however, that this was a preliminary
screening study which was not intended to be rigorous or compre-
hensive. Though a variety of cars was sampled, data were collected
from only one of each kind. Statistical variations within models
were not examined in this study. Also, the effect of time between
sampler placement in the car and the start of sampling was not
investigated in this study. Due to the precautions taken (mini-
mization of time the car door was open, entry from downwind side),
the authors feel that this effect should be small, but no quali-
tative data on tis effect are available. Finally, the NIOSH
method for vinyl cloride is intended primarily for use at room
temperature. This method was used for this preliminary study
because it is reasonably well defined, is familiar to workers in
this field, and did not require any further development work.
If a more rigorous study were to be performed, the numbers of
cars per model which would be sampled should be increased and the
effects of equilibration time could be investigated. Though the
authors feel that the results obtained in this study combined
with the limited amount of VCM in PVC now being produced indicate
that vinyl chloride in automobile interiors should not pose a
significant health hazard, some consideration might be given to
performing additional study to confirm this in 1976 cars in a
more rigorous, comprehensive manner.
19
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REFERENCES
1. Pustinger, J. V., F. N. Hodgson, and W. D. Ross. Identifi-
cation of Volatile Contaminants of Space Cabin Materials.
Aerospace Medical Research Laboratory, Wright-Patterson Air
Force Base, Dayton, Ohio AMRL-TR-66-53. 1966.
2. Pustinger, J. V. and F. N. Hodgson. Identification of Vola-
tile Contaminants of Space Cabin Materials. Aerospace
Medical Research Laboratory, Wright-Patterson Air Force Base,
Dayton, Ohio. AMRL-TR-67-58. 1967.
3. Pustinger, J. V. and F. N. Hodgson. Identification of Vola-
tile Contaminants of Space Cabin Materials. Aerospace
Medical Research Laboratory, Wright-Patterson Air Force
Base, Dayton, Ohio. AMRL-TR-68-27. 1968.
4. Pustinger. J. V., F. N. Hodgson, and J. E. Strobel. Identi-
fication of Volatile Contaminants of Space Cabin Materials.
Aerospace Medical Research Laboratory, Wright-Patterson Air
Force Base, Dayton, Ohio. AMRL-TR-29-18. 1969.
5. Pustinger, J. V., F. N. Hodgson, J. E. Strobel, and
R. L. Evers. Identification of Volatile Contaminants of
Space Cabin Materials. Aerospace Medical Research Laboratory,
Wright-Patterson Air Force Base, Dayton, Ohio. AMRL-TR-69-71.
1969.
6. Harrison, J. C. and R. Portwood. New Performance Properties
of Thermoplastics. Plastics and Polymers. December 1970.
p. 422.
7. Preliminary Assessment of the Environmental Problems Associ-
ated with Vinyl Chloride and Polyvinyl Chloride. Office of
Toxic Substances, Environmental Protection Agency, Washington.
EPA-560/4-74-001 (PB 239 110). September 1974.
8. Mieure, J. P. and M. W. Dietrich. Determination of Trace
Organics in Air and Water. J. Chromatographic Science.
11:559-570, November 1973.
9. Federal Register. 4_0_(121) Part 11:106. June 23, 1975.
20
-------
10. NIOSH Manual of Analytical Methods. U.S. Department of Health,
Education, and Welfare, Cincinnati, Ohio. HEW Publication
No. (NIOSH) 75-121. 1974.
11. Nelson, G. O., and Harder, C. A. Respirator Cartridge Ef-
ficiency Studies. V. Effect of Solvent Vapor. Amer. Ind.
Hyg. Ass. J. 35:391-410, 1974.
21
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APPENDIX A
DATA SHEETS
TABLE A-l. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Date assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature:
Seat surface temperature:
Last ventilated time:
Flow rate:
Total volume:
Location sampled:
Remarks
Ford Motor Co.
1975 Pinto
2-Door sedan
Exterior dark red
Interior black
Kettering, Ohio
5-18-75
5-28-75
6-19-75
Personnel air
Sampling pump
Bendix Model 150
SKC charcoal tube
36°C
60°C
66°C
6-18-75; 3:00 P.M.
50 ml/min
3 liters
Front seat
Back seat
Samplers placed in car at 2:00 P.M.
2:30 P.M. by remote switch.
Sampling began at
22
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TABLE A-2. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Date assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature:
Seat surface temperature:
Last ventilated time:
Flow rate:
Total volume:
Location sampled:
Chrysler Corp.
1975 Dart Sport
Exterior dark red/white
vinyl top
Interior ivory white
Dayton
4/1/75
4/15/75
7/15/75
Bendix model 150
SKC charcoal tube
27.5°C
50°C
46°C
Approx. 30 min prior to
sampling
50 ml/min
3 liters
Passenger's seat
Driver's seat
TABLE A-3. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Date assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature:
Seat surface temperature:
Last ventilated time:
Flow rate:
Total volume:
Location sampled:
Remarks
American Motors Corp.
Gremlin
Exterior dark green
Interior dark green
Dayton, Ohio
No data
5/25/75
7/23/75
Bendix model C115
SKC charcoal tube
33°C
44°C
52°C
30 min prior to sampling
50 ml/min
3 liters
Driver's seat
Battery went down after 40 min of sampling time
23
-------
TABLE A-4. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Date assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature;
Seat surface temperature:
Last ventilated time:
Flow rate:
Total volume:
Location sampled:
Remarks
Volkswagen
1975 Sedan
2-Door hatchback
Exterior red
Interior black
Dayton, Ohio
5/15/75
7/2/75
7/24/75
Bendix model 150
SKC charcoal tube
31°C
43°C
55°C
30 min prior to sampling
50 ml/min
3 liters
Driver's seat
Pump was standard at 1:45 P.M.
TABLE A-5. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Data assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature:
Seat surface temperature:
Flow rate:
Total volume:
Location sampled:
General Motors Corp,
1975 Vega
Exterior light blue
Interior light blue
Dayton, Ohio
No data
7/1/75
7/25/75
Bendix model 150
SKC charcoal tube
33°C
45°C
49°C
50 ml/min
3 liters
Driver's seat
24
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TABLE A-6. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Date assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature
Seat surface temperature
Last ventilated time:
Flow rate:
Total volume:
Location sampled:
General Motors Corp.
1975 Chevrolet
Station wagon
Exterior white top w/wood
grain sides
Interior black
Dayton, Ohio
4/1/75
4/15/75
7/29/75
Bendix model 150
SKC charcoal tube
33°C
45°C
49°C
30 minutes
50 ml/min
3 liters
Passenger's seat
TABLE A-7. SAMPLING DATA
Automobile
Manufacturer:
Model:
Colors:
Location:
Date assembled:
Date of arrival:
Date of sampling:
Sampling Conditions
Pump:
Tube:
Ambient temperature:
Interior air temperature:
Seat surface temperature;
Last ventilated time:
Flow rate:
Total volume:
Location sampled:
Datsun
1975 Datsun 710
Exterior dark red
Interior white
Dayton, Ohio
6/1/75
6/15/75
7/30/75
Bendix model 150
SKC charcoal tube
30°C
43°C
50°C
30 min prior to sampling
50 ml/min
3 liters
Driver's seat
25
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APPENDIX B
SAMPLING AND ANALYSIS OF VINYL CHLORIDE IN AIR10
VINYL CHLORIDE IN AIR
NIOSH Analytical Method
Analy te :
Matrix:
Procedure :
Vinyl Chloride Method No.:
(Chloroethene ,
Chloroethylene)
Range:
Air
Adsorption on charcoal,
P&CAM #178
0.2-1500 ng
per injection
desorption with carbon
disulfide, GC
Date Issued: 9/3/74 Precision: Unknown
Date Revised: 10/15/74 Classification: D (Operational)
1. Principle of the Method
1.1 A known volume of air is drawn through a charcoal tube to trap the
vinyl chloride present.
1.2 The charcoal in the tube is transferred to a small vial containing
carbon disulfide where the vinyl chloride is desorbed.
1.3 An aliquot of the desorbed sample is injected into a gas chroma-
tograph.
1.4 The area of the resulting peak is determined and compared with
areas obtained from the injection of standards.
2. Range and Sensitivity
2.1 The minimum detectable amount of vinyl chloride was found to be
0.2 nanograms per injection at a 1 x 1 attenuation on a gas
chromatograph.
2.2 At the recommended sampling flow rate of 50 ml/rain, the total
volume to be sampled should not exceed 5.0 liters. This value
is the volume of air containing 200 ppm of vinyl chloride which
can be sampled before a significant amount of vinyl chloride
is found on the backup section. (The charcoal tube consists
of two sections of activated charcoal separated by a section
of urethan foam. (See Section 6.2.1) If a particular atmosphere
26
-------
is suspected of containing a high concentration of contaminants
and/or a high humidity is suspected, the sampling volume should
be reduced by 50%.
3. Interferences
3.1 When the amount of water in the air is so great that condensation
actually occurs in the tube, organic vapors will not be trapped.
Preliminary experiments indicate that high humidity severely
decreases the capacity of the charcoal for organic vapors.
3.2 When two or more substances are known or suspected to be present
in the air, such information, including their suspected identities,
should be transmitted with the sample since these compounds may
interfere with the analysis for vinyl chloride.
3.3 It must be emphasized that any compound which has the same
retention time as vinyl chloride at the operation conditions
described in this method is an interference. Hence, retention
time data on a single column, or even on a number of columns,
cannot be considered as proof of chemical identity. For this
reason it is important that a sample of the bulk material
be submitted at the same time so that identity(ies) can be
established by other means.
3.4 If the possibility of Interference exists, separation conditions
(column packing, temperature, etc.) must be changed to circumvent
the problem.
4. Precision and Accuracy
The precision and accuracy of the total sampling and analytical method
have not been determined.
5. Advantages and Disadvantages of the Method
5.1 The sampling device is small, portable, and involves no liquids.
Interferences are minimal, and most of those which do occur can
be eliminated by altering chromatographic conditions. The tubes
are analyzed by means of a quick, instrumental method. The method
can also be used for the simultaneous analysis of two or more
components suspected to be present in the same sample by simply
changing gas chromatographic conditions from isothermal to a
temperature-programmed mode of operation.
27
-------
5.2 One disadvantage of the method is that the amount of sample which
can be taken is limited by the number of milligrams that the tube
will hold before overloading. When the sample value obtained for
the backup section of the charcoal trap exceeds 20% of that found
on the front section, the possibility of sample loss exists.
During sample storage, volatile compounds such as vinyl chloride
will migrate throughout the tube until equilibrium is reached. At
this time, 33% of these compounds will be found in the backup
section. This may lead to some confusion as to whether sample
loss has occurred. This migration effect can be considerably
decreased by shipping and storing the tubes at -20°.
5.3 The precision of the overall method is limited by the reproduci-
bility of the pressure drop across the tubes. This drop will
affect the flow rate and cause the volume to be imprecise,
because the pump is usually calibrated for one tube only.
6. Apparatus
6.1 An approved and calibrated personal sampling pump for personal
and area samples whose flow can be determined accurately at
50 milliliters per minute.
6.2 Charcoal tubes: glass tube with both ends flame sealed, 7 cm
long with a 6-mm O.D. and a 4-mra I.D., containing 2 sections of
20/40 mesh activated coconut charcoal separated by a 2-mm portion
of urethan foam. The activated charcoal is prepared from coconut
shells and is fired at 600°C prior to packing to remove material
possibly absorbed on charcoal. The primary absorbing section
contains 100 mg of charcoal, the backup section 50 mg. A 3-mm
portion of urethan foam is placed between the outlet end of the
tube and the backup section. A plug of silylated glass wool is
placed in front of the absorbing section. The pressure drop
across the tube must be less than one inch of mercury at a flow
rate of 1 £/min.
6.3 Gas chromatograph equipped with a flame ionization detector.
6.4 Stainless steel column (20 ft x 1/8 in) packed with 10% SE-30 on
80/100 mesh Chromosorb W (acid washed, silanized with dimethyl-
dichlorosilane). Other columns capable of performing the
required separations may be used.
6.5 A mechanical or electronic integrator or a recorder and some
method for determining peak area.
6.6 Two-mi vials which can be sealed with caps containing teflon-
lined silicone rubber septa.
6.7 Microliter syringes: 10-pJl, and convenient sizes for making
standards.
28
-------
6.8 Gas-tight syringes: 1-nfe , with open/close valve.
6.9 Pipets: 0.5-mfc delivery pipets or 1.0-nA type graduated in
0.1-nfc increments.
6.10 Volumetric flasks: 10~mfc or convenient sizes for making standard
solutions. It is preferable to have plastic stoppers for the
volumetric flasks.
7. Reagents
7.1 Spectroquality carbon disulflde.
7.2 Vinyl chloride, lecture bottle, 99.9% minimum purity.
7.3 Toluene, chromatographic quality.
7.4 Bureau of Mines Grade A helium.
7.5 Prepurified hydrogen.
7.6 Filtered compressed air.
8. Procedure
8.1 Cleaning of Equipment. All glassware used for the laboratory
analysis should be detergent washed and thoroughly rinsed with
distilled water.
8.2 Calibration of Personal Pumps. Each personal pump must be
calibrated with a representative charcoal tube in the line. This
will minimize errors associated with uncertainties in the sample
volume collected.
8.3 Collection and Shipping of Samples
8.3.1 Immediately before sampling, the ends of the tube are
broken to provide an opening at least one-half the
internal diameter of the tube (2 mm).
8.3.2 The smaller section of charcoal is used as a backup and
is positioned nearest the sampling pump.
8.3.3 The charcoal tube is placed in a vertical position during
sampling to prevent "channelling" of the charcoal.
8.3.4 Air being sampled is not to be passed through any hose
or tubing before entering the charcoal tube.
29
-------
8.3.5 Bulk air samples (i.e., samples of 10-20 liters of the
air in the environment) are taken along with personal
samples.
8.3.6 The flow, time, and/or volume must be measured as
accurately as possible. The sample is taken at
a flow rate of 50 ml/min. The maximum volume to
be sampled should not exceed 5.0 liters (See
Section 2.2).
8.3.7
The temperature and pressure of the atmosphere
being sampled is measured and recorded.
8.3.8 The charcoal tubes are capped with the supplied
plastic caps immediately after sampling. Under no
circumstances are rubber caps to be used.
8.3.9 One tube is handled in the same manner as the
sample tube (break, seal, and transport), except that
no air is sampled through this tube. This tube is
labeled as a blank.
8.3.10 Capped tubes are packed tightly before they are
shipped to minimize tube breakage during transport
to the laboratory. If the samples will spend a day
or more in transit, cooling (e.g., with dry ice)
is necessary to minimize migration of vinyl chloride
to the backup section.
8.3.11 Samples received at the laboratory are logged in and
immediately stored in a freezer (around -20°) until time
for analysis. Samples may be stored in this manner for
long periods of time with no appreciable loss of vinyl
chloride (2 months). Even around -20°C, vinyl chloride
will equilibrate between the two sections of charcoal,
i.e., will migrate to the backup section. This
phenomenon is observable after two weeks and may be
confused with sample loss after 1 to 2 months.
8.4 Analysis of Samples
8.4.1 Preparation and Desorption of Samples. In preparation
for analysis, each charcoal tube is scored with a file
in front of the first section of charcoal and broken open.
The glass wool is removed and discarded. The charcoal in
the first (larger) section is transferred to a small vial
containing 1 ml of carbon disulfide. (Note: the addition
to the CS2 is important.) The vial is topped with a
30
-------
septum cap (See Section 6.6). The separating section
of foam is removed and discarded; the second section
is transferred to another small vial containing 1 ml
of CS2• These two sections are analyzed separately.
Tests indicate that desorption is complete in 30 minutes
if the sample is agitated occasionally during this period.
In any case samples should be analyzed within 60 minutes
after addition to CS2-
8.4.2 GC Conditions. The typical operating conditions for the
gas chromatograph are:
1. 40 cc/min (80 psig) helium carrier gas flow
2. 65 cc/min (20 psig) hydrogen gas flow to detector
3. 500 cc/min (50 psig) air flow to detector
4. 230°C injector temperature
5. 230°C manifold temperature (detector)
6. 60°C isothermal column temperature (oven).
8.4.3 Injection. The first step in the analysis is the injection
of the sample into the gas chromatograph. To eliminate
difficulties arising from blowback or distillation within
the syringe needle, one should employ the solvent flush
injection technique. The 10-u£ syringe is first flushed
with solvent several times to wet the barrel and plunger.
Two microliters of solvent are drawn into the syringe to
increase the accuracy and reproducibility of the injected
sample volume. The needle is removed from the solvent
and the plunger is pulled back about 0.4 \& to separate the
solvent flush from the sample with a pocket of air to be
used as a marker. The needle is then immersed in the
sample, and a 5-y?, aliquot is withdrawn to the 7.4 y£ mark
(2 p£ solvent + 0.4 y£ air + 5 \iH sample = 7.4 u£). After
the needle is removed from the sample and prior to injection
the plunger is pulled back a short distance to minimize
evaporation of the sample from the tip of the needle.
Duplicate injections of each sample and standard are made.
No more than a 3% difference in area is to be expected.
8.4.4 Measurement of area. The area of the sample peak is
measured by an electronic integrator or some other
suitable form of area measurement, and preliminary results
are read from a standard curve prepared as discussed below.
8.5 Determination of Desorption Efficiency
8.5.1 Importance of determination. The desorption efficiency of
a particular compound can vary from one laboratory to
another and also from one batch of charcoal tc another.
Thus, it is necessary to determine at least once the
percentage of vinyl chloride that is removed in the
31
-------
desorption process. Desorption efficiency should be
determined on the same batch of charcoal tubes used in
sampling. Results indicate that desorption efficiency
varies with loading (total vinyl chloride on the tube),
particularly at lower values, i.e., 2.5 Mg.
8.5.2 Procedure for determining desorption efficiency. Charcoal
tubes from the same batch as that used in obtaining samples
are used in this determination. A measured volume of vinyl
chloride gas is injected into a bag containing a measured
volume of air. The bag is made of Tedlar (or a material
which will retain the vinyl chloride and not absorb it)
and should have a gas sampling valve and a septum injection
port. The concentration of the bag may be calculated
knowing room temperature and pressure. A measured volume
is then sampled through a charcoal tube with a calibrated
sampling pump. At least five tubes are prepared in this
manner. These tubes are desorbed and analyzed in the same
manner as the samples (See Section 8.4). Samples taken
with a gas tight syringe from the bag are also injected
into the GC. The concentration in the bag is compared to
the concentration obtained from the tubes.
The desorption efficiency equals the amount of vinyl
chloride desorbed from the charcoal divided by the quantity
of vinyl chloride contained in the volume of synthetic
atmosphere sampled, or
quantity vinyl chloride from charcoal
concentration vinyl chloride .. volume atmosphere
in atmosphere sampled
9. Calibration and Standards
CAUTION: Laboratory Operations Involving Carcinogens
Vinyl chloride has been identified as a human carcinogen
and appropriate precautions must be taken in handling this
gas. The Occupational Safety and Health Administration
has promulgated regulations for the use and handling of
vinyl chloride. They may be found in 29 CFR 1910.93q
(Section 1910.93q in Title 29 of the Code of Federal
Regulations available in the Federal Register, Vol. 39,'
No. 194, Friday, October 4, 1974, pp. 35890-35898).
A series of standards, varying in concentration over the range of
interest, are prepared and analyzed under the same GC conditions and
during the same time period as the unknown samples. Curves are
established by plotting concentration in jig/1.0 mH versus peak area.
There are two methods of preparing standards and as long as highly
purified vinyl chloride is used, both are comparable.
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NOTE: Since no internal standard is used in the method, standard
solutions must be analyzed at the same time that the sample analysis
is done. This will minimize the effect of day-to-day variations of
the FID response.
9.1 Standard Preparation
Gravimetric Method - Vinyl chloride is slowly bubbled into a
tared 10-ml volumetric flask containing approximately 5 ml
of toluene. After 3 minutes, the flask is again weighed. A
weight change of 100-300 mg is usually observed. The solution
is diluted to exactly 10 ml with carbon disulfide and is used
to prepare other standards by removal of aliquots with different
sized syringes. Subsequent dilution of these aliquots with
carbon disulfide results in a series of points that are linear
from the range of 0.2 nanograms per injection, the minimum
detectable amount of vinyl chloride, to 1.5 micrograms per
injection.
Volumetric Method - A 1-ml gas sample of pure vinyl chloride
is drawn into a gas-tight syringe and the tip of the needle is
inserted into a 10-ml volumetric flask containing approximately
5 ml of CS2 • The plunger is withdrawn slightly to allow the
CS2 to enter the syringe. The action of the vinyl chloride
dissolving in the CS2 creates a vacuum and the syringe becomes
filled with the solvent. An air bubble (~2%) is present and
was found to be due to the void volume in the needle of the
syringe. The solution is returned to the flask and the
syringe is rinsed with clean CS2 and the washings added to
the volumetric. The volumetric is then filled to the mark
with CS2- Other standards are then prepared from this stock
solution.
Standards are stored in a freezer at -20°C and are found to
be stable at this temperature for three days. Tight-fitting
plastic tops on the volumetrics seem to retain the vinyl
chloride better than ground glass stoppers.
10. Calculations
10.1 The weight, in yg, correspondong to each peak area is read from
the standard curve for vinyl chloride. No volume corrections
are needed, because the standard curve is based on yg/1.0 mfc
CS2 and the volume of sample injected is identical to the
volume of the standards injected.
10.2 Corrections for the blank are made for each sample.
Vg -•-- Mgs -
where :
ygs = yg found in front section of sample tube
yg = yg found in front section of blank tube
A similar procedure is followed for the backup sections.
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10.3 These values are further corrected for the desorption efficiency
at the level of vinyl chloride measured.
UB
Corrected Pg = -, - '——. — 6 ee. .
desorption efficiency
10.4 The corrected amounts present in the front and backup sections
of the same sample tube are added to determine the total amount
of vinyl chloride in the sample.
10.5 The concentration of the vinyl chloride in the air sampled is
expressed in mg/nr*, which is numerically equal to yg/liter of
air
, 3 ,. total yg (Section 10.4)
mg/nr> = pg/X, = - a-^ - -
where :
V is the volume of air sampled
10.6 Another method of expressing concentration is ppm, defined as
y£ of vinyl chloride gas/liter of air
/» v 24.45 ... 760 T+273
ppm= yp/* X ~ * ~~ X
where :
P = pressure (mm Hg) of air sampled
T = temperature (°C) of air sampled
24.45 = molar volume (£ /mole) at 25°C and 760 mm Hg
62.5 = molecular weight (g/mole) of vinyl chloride
760 = standard pressure (mm Hg)
298 = standard temperature (°K)
11. References
11.1 Hill, R.H. , C.S. McCammon, A.T. Saalwaechter , A.W. Teass, and
W.J. Woodfin, "Determination of Vinyl Chloride in Air," in
preparation.
11.2 White, L.D., D.G. Taylor, P. A. Mauer, and R.E. Kupel, "A
Convenient Optimized Method for the Analysis of Selected
Solvent Vapors in the Industrial Atmosphere," Am. Ind. Hyg.
Assn. J., 31, 225 (1970).
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TECHNICAL REPORT DATA
(Please read Inzlructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-124
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Sampling of Automobile Interiors for Vinyl
Chloride Monomer
5. REPORT DATE
Mav 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
William H. Hedley, Joseph T. Cheng,
Robert J. McCormick, and Woodrow A. Lewis
8. PERFORMING ORGANIZATION REPORT NO.
MRC-DA-535
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1AB015; ROAP 21AXM-073
11. CONTRACT/GRANT NO.
68-02-1404
Task 1, Change 2
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task final; 6-9/75
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTESIERL-RTP project officer for this
Mail Drop 62, Ext 2547.
report is David K. Oestreich,
16. ABSTRACT
The report gives results of a study to qualitatively identify
organic pollutants in the air inside new automobiles. In recent
years, concern has developed over the concentration of organic
vapors inside new automobiles., A literature search first identi-
fied numerous volatilization products from plastics used in the
construction of automobile interiors. Charcoal tubes were used to
collect air samples in seven test vehicles. Vinyl chloride mono-
mer concentrations of 0.4 to 1.2 ppm were detected in two vehicles,
The concentrations in the other five test vehicles during this
preliminary study were below the detection limit of 0.05 ppm.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Automobiles
Vinyl Chloride
Organic Compounds
Plastics
Vaporizing
Air Pollution Control
Automobile Interiors
Vinyl Chloride Monomer
13B
13F
07C
111
07D
8. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
39
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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