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 ------- 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. ------- 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 ------- 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 ------- 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 ------- 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 ------- 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. ------- 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. ------- 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. ------- 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 ------- 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. ------- 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. ------- 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. ------- 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 ------- 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. ------- 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 ------- 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 ------- 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 ------- 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. ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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. 32 ------- 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. 33 ------- 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). 34 ------- 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) 35 ------- |