Document N2wBqwdgXZ9LdLBEX7eEva6ZQ

OWL ^Viemiea^- INC. interoffice MEMORANDUM Subject Date 29 January 1975 Photochemical Oxidation of Vinyl Chloride To -- Distribution_____________________ From ___ J. T. Barr` Distribution: A. R. Adams T. L. Carey A. J. Diglio R. Fleming J. T. Sebastianel11 W. M. Smith _________ _________ (Lection, 0'9ni2<tion, or Department) Valley Forge________________ (Lection, Orgkniction, or Depertm.nt) . Bob Laundrie - General Tire, Akron In my 9 January report of a visit to EPA in Research Triangle I stated that I had been referred to a Dr. Altschuler for informa tion on Agency studies on vinyl chloride in the atmosphere. I have not been able to reach Dr. Altschuler, but did contact a Dr. Joseph Bufallni of his group. Dr. Bufallni was not able to cite a reference to the reported 6-hour half-life of vinyl chloride in air given in the Briefing Report dated October 15, 1973. He did know of the work sponsored by Diamond-Shamrock at Battelle and reported earlier through MCA. This was the smog chamber comparison of VCM with Toluene. (Dr. H. Everson of Diamond-Shamrock was Dr. Altschuler's professor at school.) He did not mention the Dow work that also has been reported. Some work was done by EPA three years ago In a 335 ft^ chamber, and more recently in a 9.1 meter glass tube, comparing VCM to ethylene. This work has been submitted to Environmental Science and Technology, and a draft is attached. He knew of no other studies in progress and fplt that none were needed, since It has been shown that VCM i^rrvdt persistent, and the oxidation products have been identified. / /dw <320) AP060f3336 C&cidatioa of Ethylene and Ealogenated Hydrocarbons at Low Concentrations by 7 <-J5 , Brace W. Gay, Jr. Bi chard C. Noonan Joseph J. Bufalini 'f-S Photochemistry and Gas Kinetics Section Atmospheric Chemistry and Physics Branch Chemistry and Physics Laboratory Environmental Protection Agency Research Triangle Park .Thephotooxidatioa of several haloearbons in the presence of oxides of nitrogen was investigated. These include, vinyl chloride* i$- l^-di--chloroethylene, 1, 2-dichloroethyleae, trichloroethylene, tetrachloroethylene, chloroform, and chloroform in the presence of ethylene, and ethylene. The latter compound i.e. ethylene was photooxidized to enable comparisons of the reactivity parameters. ' Vinyl chloride in the presence of NO and ultra-violet light leads to the formation of formic acid, hydrochloric acid, carbon monoxide, . -* formaldehyde, ozone, and a small quantity ox formyl chloride. 1, 1-- . dichloraethylene reaction lead to the formation of products similar to those found with vinyl chloride. However, phosgene and nitric acid were also observed. 1,2-iichioroethylene also leads to similar products as those of vinyl chloride with the exception of formaldehyde formation, larger quantities of HC1 are observed for the reaction. This product probably arises from formyl chloride decomposition since this compound quickly thermally decomposes to HC1 and CO. The photooxidation of trichloroethylene resulted in the formation of phosgene and formyl ' Chloride as veil as the other products (EC1, CO, HNO^, and HCOOH) . The tetrachloroethylene was found to be the least reactive of all the chlorinated erhylenes. The products observed were ECGC2, EC1, CO, COCl^, and 0^. Chloroform was irradiated with ethylene largely be cause this compound was expected to be very unreactive when photoaxidized ..alone. The products arising from the chlorofom-ethyleae-XO system, are CO, formaldehyde, 0^, phosgene, and formic' acid. 32 * AP00013337 Fcoa these studies. It yas found that vinyl chloride id approximately 60 percent as reactive as ethylene in terns of cpd reacted. In terms of NO oxidation, the vinyl chloride is 70 percent as reactive. .The ozone produced from a vinyl chloride-XO system is approximately one-half that produced with the ethylene-NO^ systems. In terns of 0- reaction, the rate' constant for the vinyl chloride-0 reaction is 1/10 that of the ethylene-O, reaction.- The rate constant for the 0- - vinyl chloride reaction is 0.3 X 10 ppm min. AP00013338 OXIDATION' OF ETHTLENE AJiD EALOGENATED HYDROCARBONS Bruce V. Gay, Jr*, Richard C. Noonan, Joseph J* Bufallot INTRODUCTION Vinyl*chloride has recently received notoriety by being linked., to angiosarcoma of the liver, a'rare type of cancer in the human liver. Exposures to vinyl chloride are greatest in occupational situations and in the past when vinyl chloride was used as pro pellent In aerosol products in many hose use products. (The use as propellent has since been banned.) Atmospheric emissions are primarily from vinyl chloride and polyvinyl chloride production plants. Vinyl chloride losses have been estimated at approximately 6 percent based primarily on material balance studies of these types of plants. It is estimated that emissions of vinyl chloride currently'exceeds 90 million Eg annually. Of these emissions 90 percent are estimated, ns emanations from polyvinyl chloride plants. Monomer plants are*' -responsible for less than 10 percent. Because of concern vith'pol-............. lutants In the ambient atmosphere and core. so because of the health implications of vinyl chlori.de, the Environmental Protection Agency has initiated a program to make extensive atmospheric vinyl chloride measurements in the vicinity of vinyl chloride -- polyvinyl chloride production sources to determine ambient exposure concentrations which might effect the general populsjusi'"^ The measurements to date suggest that in the majority of cases, samples obtained some distance downwind from plants are below 1 ppm (v/v) vinyl chloride. Although concentrations of vinyl chloride in the at mosphere cay be low it-is just one of cany balogenated compounds emitted into the atmosphere. There is in general a paucity of Information on possible environmental effects arising from the degradation of vinyl chloride as veil as other halocarbons in general in the atmosphere. The production of halogenaced hydrocarbons in the United States alone AP00013339 I totaled core than 16 billion pounds in 1966 (Tariff 1969)* Information concerning the degradation products of halogenated compounds Is critically seeded. The work presented here is concerned primarily with the oxidation of the chlorinated ethylene conpounds. * ggPgpjgyTAL The ultraviolet irradiations were carried out in. two different chambers. The first chamber was a 335 ft^ aluminum chamber equipped with polyvinyl fluoride film windows (Korth, et.al., 1964). This chamber was equipped with fluorescent blacklights- and- sunlight lo cated externally. The kd value for the chamber was 0.4 min. ^ (Tuesday 1961). The chamber was preheated with infrared lamps be fore the start of the irradiations and operated at 32 + 1 C at a relative humidity of approximately'33 percent.^ The gaseous reactants were charged directly into the chamber by calibrated syringes. Nitrogen dioxide was analyzed colorimetriesHy (Saltzman, 1954) Nitric oxide was analyzed as nitrogen dioxide after oxidation with dichromate paper (Wilson and Xopczyaski, 1968). . Oxidant was da-: ............... termdned ually By the colorimetric 1 percent neutral potassium Iodide method (3vers and Saltman, 1958). The ethylene and vinyl chloride were analyzed by gas chromatography. The second chamber was a, 9.1 meter long by 0.31 meter inside dl--. anater borosicilate glass tide made; up of 6, 1.52 meter sections. Around the tube are fluorescent blacklights with energy maxima at 3660 JL This photochemical.xeactox also serves as a long path I-R. cell. An eight mirror optical system is -ased in order to achieve multiple reflections. . The cell is .capable xf 72 n'ceters where n is any in teger from 1 to 25* The .optical parti length used for these experiments __ 2. were 500 meters. The spesmromjeter 2s a Digilab FIS rapid scan Miehelson Interferometer which- is,capable of 0.125 cm--i resolution (Eanst et.al., 1973)v liquid nitrogen cooled detectors ara used in this system. The reactants fmr the experiments are-introduced into the long path cell through a.manifold frea'-n.glass gas handling system that AP000I3340 had two known voltae bulbs. By using 0-50 Torr and 0-800 Torr pressure gauges and the known volume bulbs, the calculated quantitities of gases could be introduced. The reactants were used as obtained from the manufacturers without further laboratory pre-purification. It is doubtful that any impurities were present since no unexpected or unidentified bands were present'in -the infrared with detection limits of less than one-tenth part per million. RESULTS '' I The photooxidation of the chloroethylenes Is summarized in. Table 1. Exact comparisons on the reactivities is not possible since the same hydrocarbon to NO^ ratio vas not maintained with each compound. However, since the ratio was approximately constant, the reactivities are at least qualitatively correct.* The various runs made on each system will be discussed separately. 3" Chamber of 335 ft Volume .. Ethylene The photooxidation of ethylene in the presence of is shown in Figure 1. This hydrocarbon being a major constituent of auto exhaust hs.3 been studied extensively. It is shown here primarily for comparative-purposes. After 200 minutes irradiation, approximately 67 percent of the ethylene had reacted. The maximum occurs at ap proximately 90 minutes and the 0^ reaches a t**^TM*- of 0.82 ppm at 300 minutes. The formaldehyde maximum of 1.06 ppm also occurred'at 300 min utes. Vinyl Chloride _ The reaction of vinyl chloride In the presence of is shown in Figure 2. The conditions for this photooxidation are the same as those for the ethylene. After five hours irradiation, approximately 39 percent of the vinyl chloride had reacted. The N0^ occurs at 130 min utes. The ozone observed after 330 minutes was 0.44 ppm. The formaldehyde concentration reached a maximum of 0.32 ppm at 140 minutes and leveled off AP00013J41 at tills value for the remainder of the run. This suggests that the production rate of formaldehyde is approximately equal to the rate of destruction after 140 minutes of irradiation. In terms of NO oxidation, the vinyl chloride is approximately 70 percent as reactive as ethylene. In terms of compound reacted, the vinyl chloride is about 60 percent as reactive as ethylene. The ozone produced at the close of the run i.e., 330 minutes, appears to he one-half as great for the vinyl chloride case compared to the ethylene case. However, fox the vinyl chloride photooxidation the elope of ozone versus time curve is' still positive even at the close of the rim. This suggests that with continued irradiation the ozone concentration would build-up to a higher value. At the close of the Irradiation, approximately 20 percent of the reacted vinyl chloride appeared as formaldehyde, where-as*33 percent of the reacted ethylene appeared as formaldehyde in the ethylene photooxidation. The higher formaldehyde yield from ethylene Is to he expected since both ends of the molecule can give rise to formaldehyde. Long Path Infrared Chamber ................................ ....... - -............ Ethylene The photooxidation of ethylene and in the 700 liter LPIR cell is shown in Figure 3. After 240 minutes irradiation approximately 82 percent of Che ethylene had reacted. The mmrtjnun ozone concentration of 1.23 ppm was formed at about 200 minutes. After 180 minutes irradiation the formaldehyde concentration became constant with increasing irradiation tine. Vinyl chloride -, . The data for the irradiation of vinyl chloride in the presence of IfOj is shown in Figure 4. At 160 min* irradiation tine, approximately 40 percent of the vinyl chloride had been reacted compared to 25 per--'. 3 cent reacted for the 335 ft chamber. The reaction Is more rapid in the LPIR chamber for two reasons: (1) The light intensity used was greater (kd approximately 0.6 min.*1 versus kd - 0.4 nia""^ for the 335 ft. chamber) and (2) The starting NO^ was exclusively KO2 vhich enabled 0^ to build up more quickly. The LPIR chanoer system optics for ia-situ measurements gave direct product analysis. The products observed were, formic acid, hydrochloric acid, carbon monoxide, formaldehyde* and ozone. Trace amounts of formyl chloride and nitric acid were also detected but were not quantified. The formyl chloride is thermally unstable and decomposes to BC1 and CO. A small fraction of a ppm of C02 is probably produced but this goes undetected since part of the optical system is exposed to room air vhich is laden with approximately 350 ppm of CO-. Weakly absorbing unidentified -1 Z --1` peaks were observed at 790 cm and 1165 cm In an attempt to identify these bands, 3--chloropropene-NO^ was phctocxidized to pro duce the chlorinated PAN. The products from this photooxidaeion had peaks at 790' and 1165 cm"1. This suggests.that a chlorinated peroxyacetyl type compound is produced. The compound produced from these systems had" the larger absorption, at 790 cm 1 than at 1165 cm 1 compared to the case of PAN, where.aiie absorption at 1162 cm"1 is larger than at 790 cm \ At the conclusdcny-of the irradiation i.e* 160 min utes, 76 percent of the original xafijon. could be accounted for as pro-* ducts and 87 percent of the Cl cnLCbe accounted for. 1, 1--Dichloroethylene The 1, 1--dichloroethylene photpohidizes much core quickly than vinyl chloride. After 140 n 1 nitres ^irradiation (Figure 5) , approximately 85 percent of the compound has xeactad- The products observed were those found for vinyl chloride plus phosgene and a large unidentified peak at 720 cm This latter peak could he xhlorcacetyl chloride -- a product from the ozonolysis of 1,.^.-dichloroafhylene (Hull et. al., 1972). How ever, this compound shdhld..he amstabln in the presence of water vapor. 1, 2 -- Dichloroethylene The photooxidation of '1,^2-dichloroethylcne is shown in Figure 6. AP000I3343 The reactivity of this halocarbon is also greater than vinyl chloride hut less than 1, l-dichloroethyleae. The products from the photooxidation of this compound are similar to those observed with vinyl chloride with the exception that no formaldehyde is observed. Hydrochloric acid appeared to be the largest product accounting for 45 percent of the chloride con sumed. Trichloroethylene Trichloroethylene was photooxidized a number of years ago by Eopezynski (1963). This investigator found that this compound reacted faster than ethylene but slower than propylene. This compound was reinvestigated in order to establish the formation of phosgene and formyl chloride as was suggested in Kopezynski's work (Aitshulier and Bufalini, 1971). In Figure 7 is shown the phopodlssoclacion of tri chloroethylene with phosgene as product. Formyl chloride was also observed hut its concentration could not he quantified. Tetrachloroethylene The photooxidation of tetxachloroethylene completes the study of the reactions of the substituted ethylenes. As can be seen from Figure 8 the reactivity of this compound is quite low. It is the least re active of the chlorosubstituted ethylenes. Only 0.37 ppm or 7.5 percent of the compound reacted over a period of 3 hours. Formic acid, HC1, CO, COC^, and a little ozone were produced over the three--hour irradiation. The presence of a small quantity of ozone suggests that nitric oxide inhibition is occurlng since the nitrogen dioxide concentration is quite high after 3 hours irradiation. Vinyl Chloride -- Ozone Reaction Our photooxidation of vinyl chloride in the presence of NO suggest 2C that this compound is moderately reactive. Its reactivity appears to be approximately 60 percent that of ethylene. Since it is moderately reactive, the 0^ -- vinyl chloride reaction should also be moderately reactive. The results of this investigation are shown in Figure 9. The primary products AP00013544 of the ozone-vinyl chloride reaction are; CO, CH^O, ECOOH, and a snail quantity of HC1. The rate constant for the reaction assuming a second -3 --I -l order mechanism is 0.34 X 10 ppm min . This value Is approximately 1/10 that for the ethylene-ozone reaction. (3 S 10 ^ ppm * rain re commended by Garvin and Hampton (174). This ratio l.e. k^c/ke is truch greater than that found by Williamson and Cvetanovic (1968) in CCl^ solution. The stoichiometry of the reaction shown in Figure 9 suggest that more ozone than vinyl chloride is consumed. However, the ozone curve has cot been corrected for thermal and heterogenous degradation of ozone. The czone degraded in the LPIB chamber at a'xate of 4.7 percent per hour. If this same correction is used for the ozonolysls run, the amount of 0^ con sumed is 3 hours is only approximately 0.5 ppm. Thus, more vinyl chloride than ozone is consumed during the reaction - an observation compatible with other olefin-ozone reactions (Gull et.al.*1972, Bufalini, and Altshuller, 1965, Wei and Cvetanovic 1963) . Chloroform .. .. . The irradiation of 9.85 ppm of chloroform with 1-08. ppm of ........................ resulted in almost no reaction of chloroform. A 6 percent reaction in 230 min. was observed but there was considerable uncertainty -in this value. All. other reactivity parameters were very low. With 230 min utes irradiation, .05 ppm- of COCl^,, 0i2 ppm of HCOOH and 0.08'ppm of CHjO was produced. Ho ozone was produced during the irradiation. The slight amount of ECOOS and CH^O are probably a result of wall contam ination. Chloroform-Ethylene--KQ^--Systems Since chloroform is imreactive when Irradiated alone In the presence of NO^, It was investigated in the presence of ethylene. In Figure 10 are shown these data. In general'^ even in the presence of a moderately reactive hydrocarbon, the reactivity of chloroform is quite, lew. Over a period of 3 hours irradiation, only 17 percent of the chloroform reacted. In contrast, over 54 percent of ^tie ethylene had reacted. Host of the APOOOt3345 xeactica product produced from chloroform is phosgene with only a. trace of formyl chloride and HC1. No CCl^ was observed in this or the tr and tetra chlorinated ethylene systems. The amount of ozone and CO produced from this system is not significantly different from that produced from the irradiation of ethylene alone under similar conditions- Thus, with ethylene at 1.8 ppm and NO^ at .8 ppm, 1.24 ppm of 0^ was produced at 3 1/2 hours. The CO level -was 1.56 ppm at 4 hours. In the chloroform-ethylene system with 2.21 ppm of ethylene and 1.Z8 ppm of N0^> the 0^ produced was 1.24 ppm at 3 1/2 hours and CO is X.54 ppm. . - DISCUSSION . . Tbe products arising from the oxidation of chlorinated ethylenes are not unexpected when compared to products arising from ethylene oxidation. The initial attack on the double bond is a result from a combination of reactions. These include; (1) Oyatoa reaction arising from the photolysis [NO^ + hv '-* NO + 0 (2) 0^ reaction from 0 + 0^ (M) (3) OH reaction from ENO^ photolysis' or front an organic free radical decomposition and (4) HOj and HO^................ reactions. Products observed can -arise from fragmentation of the chloro-- ethylene molecule after attack from one of the above species. If ozone is taken for example, the following set of reactions would occur withvinyl chloride. Cl) C3 + CHpl - C22 - E2C0 + 02 CfiCl (2) HC1C0 + 02CH2 C3) 2CH2 OH + CHO -- <4) CEO + 0Z -* ho2 + CO <5) SC1C0 EC1 + CO <6> HC1C0 + H,,0 HCOOH + HC1 APOOOt3346  This, mechanism is not aeaat to be complete since a large numberof reactions can be written with the free radicals -arising from the pho cooxidation. Also, the role of NO^ is not shown and many reactions can be written involving nitrogen containing compounds. Instead, the above reactions as shown only to suggest hov some of the products are produced* The foray1 chloride can arise from reaction 2* This pro-- duct has been observed by Its spectra but has not been quantified largely because of its instability* Bisatsune and Helcklen (1973) have shown, that formyl chloride gas is thermally unstable with a halflife of approximately 20 minutes* They report that the thermal de composition products are HC1 and CO. Soth products have been observed In the photooxidation of the chloroethylenes. The.HCl concentration is In every case greater than CO* This observation is compatible with the formation of HC1 via reaction (6) . Phosgene that has been, observed as a product , from the 1, 1 dlchlora, the trlchloro and tetrachloroethylenes* is expected to arise from the same type of reaction that produced formyl chloride i*e* <7) 03 + CC12 - CH^ CC120 + 02CH2 * CC1202'+ CHjO --- ----.............................----- No CC14 was detected in any of the Irradiations involving the chloroethylenes. This observation is not in agreement with the re cent findings of Singh et.al* (1974). These investigators report C&4 formation from the photooxidation of tetrachloroethylene and suggest that a large fraction of the ambient levels of CCl^ could arise from the degradation of chlorohydroearbons. It is interesting to note that most of the irradiations gave rise to high concentrations of ozone* Also, as shown In the case of the chloroform-efchylene-NO^ reaction, the quantity of ozone produced was not significantly different from that produced from ethylene-NO^ alone* This observation suggest that chlorine atoms are not produced* If chlorine atoms were produced, then the following reactions would lead to ozone destruction: Cl + o3 CIO + 0. <9) CIO + o3 -y- Cl + 20. (10) CIO + CO Cl + CO. /-> vCO. AP00013347 This mechanism for ozone-destruction has been proposed for S'^'tipper atmospheric chemistry (Molina and Rowland 1974). However, <'i*? it is possible that a more complete mechanism for these chamber type conditions, would show no such ozone depletion when applied ,".?Y to lower atmospheric conditions even la the presence of chlorine --..^atoms. This study has shown that most of the chlorinated ethylenes are of moderate reactivity and are photcoxidized to compounds such as -l&S > formaldehyde, hydrochloric acid, phosgene, formyl chloride, and m tentatively chloroacetyl chloride and a chlorinated peroxyacyl type compound. It is, therefore, possible that such products l.e., phosgene, formyl chloride and hydrogen chloride will be produced in the ambient atmosphere under stagnant meterological conditions around the vicinity of sources emitting these halocarbons- It is doubtful, . -*& however, that high concentrations of such products could 'be observed, since these products are usually only a fraction of the original reactant, which are found at low concentrations. a? ST Hi.- <3^T APOOOI3348 \ LITERATURE CITED Altshuller, A.P., Bufaliai, J.J., Environ. Sei, Technol., 5., 39 (1971). Bufallni, J.J., Altshuller, A.F., Can. J. Chen. 43, 2243, (1965). Byers, D.H., Saltman, B.E., J. Am. Indust. Eyg. Assn., 19 > 261 (1955). Garvin, D., Hampton, R.F., "Chemical Kinetics Data Survey VII. Tables of Rate and Photochemical Data- for Modelling of the Stratosphere (Re vised)," National Bureau of Standards 74-430, Washington, D.C. 1974. Eanst,. P.L., Lefoha, A.S., Gay, B.W., Jr., Applied Spectroscopy, 27, 183 (1973). Risatsune, I.C., Heicklen, J., Center for Air Environment Studies Report. No. 309-73, University Park, Pa., (1973). Hull, L.A., Eisatsune, I.C., Heicklen, Julian, Center for Air Environment Studies Report No. 270-72, University Park, Pa., (1972). Sopezynskl, S.L., Prive Communication to J.J. Bufalini (1968). Sorth, M.W., Rosa, A.3., Stallman, R.C., J.-Air Follut. Concr. Assn., .14, 168 (1964). . Molina, M. J.Rsviand, T.S., Nature, 249. 810 (1974). Saltzman, B.E., Anal. Cheat., 26, 1949 (1954).. Singh, H.S., Lillian, D., Applebg, A., Lobban, 1. Private Communication (1974) - Tariff Commission Reports, Miscellaneous Chemicals, Washington, D.C. (19,69). Tuesday, C.S., "The Atmospheric Photooxidation of Trans-2-Butene and Nitric Oxide," in Chemical Reactions in the lower and Upper Atmosphere, ' tnterscience. New York, 1961, p. 1-49. Williamson, D.G., Cvetaaovic, R.J., J. Amer. Chea. Soc. 90, 3663 (1968). Wilson, D., Kopczynski, S.L., J. Air Pollut, Cent*. Assn., 18, 160 (1968). APOOOt 3350 Holocarbon TABLE 1. REACTIVITY PARAMETERS FOR CHLOROETHYLENES HC/NO^ 140 Min. Reactivity HC t(min). O3SB . o/olIC 11C1 . CO max* reacted ppn ppm C0C121 Vinyl Chloride 1, 1-Dichloroethylcne It 2-Dichloroethylene Trichloro ethylene Tctrachloroethylene r 3.0 2.15 3* .0 2.66 2.83 4.63 - 4.85 ` >'160 125 5.0 >150 ^.45 115 5.0 >180 t 0.95 2.20 2.07 2.07 0.07 34 83 66 66 7.0 1.25 1.12' 1.20 0.87 None 0.72 2.90* 1.45 1.75 * .V** 0.80 None 0.47 0.42 0.27 0.12 Lise of Figures figure 1. Figure 2. 2 Irradiated Ethylene and NO in 335 ft Chamber x3 Photooxidation of Vinyl Chloride and NO^ In 335 ft Chamber Figure 3. Photolysis of Ethylene and N02 in LPIR Chamber Figure 4. "Vinyl Chloride and NO^ LFIH. Chamber Irradiation Figure 5. Photolysis of 1, 1-Dichloroethyleae and N02 Figure 6. 1, 2-Dichloroathyletxe and NO^ Photooxidation in LPIH. Chamber Figure 7. Trichloroethylene Irradiated in the* Presence of NO^ Figure 3. TetrachXoroethylene, N02 Irradiation Figure 9* Ozcnization of Vinyl Chloride Figure 10. Photooxidation of Chloroform in the Presence of Ethylene and N02 AP000I3351 AP000I3352 ""S1' '. Ka APOOO13353 TIME IN MIN. AP000I3354 CONC.ppm M U * f?0N 3 a iU 0 1 H 9 U f|tA dO NOliVIQVUUl AP00013355 t im e IN min. AP000I335* APOOb13357 y AP00013358 "1 . ^ TETRACHIOROETHYLENS+ NO* *o* _ ppm Ha FKC3UCTS /vjw'awix IM1ADIATI0NOFTETRACHLOnOETHYUNEN02 .* AP00013359 \ t 1i * APOOO13360 '1 covc. tprrt> s - I TKt; 1 :2*J. 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