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R&S 110365 BIO-MEDICAL RESEARCH DOCUMENT DESCRIPTION FORM Duplicate In all cards: 63 68 69 76 year as-1961- File number [Right justify [Numeric only] Author(s), as Last Name FS (No Punctuation) and coden for journal as JAMA preceeded by one blank space 1______________ 20 21 40 41 / /> 77 78 Sub-Index Code 60 61 62 Title of Report; end with space-hyphen-hyphen-space. Follow with Index Terms, separated from each other with comma-space. Avoid other punctuation; do not abbreviate. Source (Journal, Vol., Number, Pages, Date) 12 T" -- / 1 r>& //y'v // i/ -e_ CA L3 o - 3n Brief Summary 12 10 SUMMARY: 61 62 31 32 61 62 61 62 63 64 Pittsburgh PCS 12x30 activated carbon is found to be the most suitable of the commercially available carbons tested for personnel sampling of vinyl chloride, vinylidene chloride, and methyl chloride. ^ The carbon is desorbed with C$2 at dry ice temperature or with a thermal desorption technique. 003327; \ Monitoring personnel exposure to vinyl chloride, vinylidene chloride and methyl chloride in an industrial work environment L. W. SEVERS and L K. SKORY Dow Chemical U.S.A., Midland, Michigan 48640 r &S 110366 Introduction Late in 1973, information became available linking angiosarcoma of the liver (a rare form of cancer) with occupational exposures to high levels of vinyl chloride. Reacting to this, OSHA issued an Emergency Temporary Standard for vinyl chloride exposures limiting them a a max imum of 50 ppm. Subsequendy, a reduction of this standard was proposed and became effec tive whereby the permissible eight hour timeweighted average exposure may not exceed 1 ppm, with a ceiling of 5 ppm averaged over no more than a 15 minute sampling period.1 A study was undertaken to develop a reliable method for long and short term personnel sampling and analysis of vinyl chloride. Methyl chloride and vinylidene chloride were also in cluded in this investigation because of their chemical similarity to vinyl chloride. Breakthrough Studies Field use of commercially available adsorbent carbon tubes gave significantly differing results than sophisticated chlorohydrocarbon analyzers .thus indicating that existing adsorbents were not adequate to quantitatively define vinyl chloride exposures to workers. Available carbons were obtained and studied for breakthrough time by passing 200 ppm (parts per million by volume in air) vinyl chloride through a 30 ml bed of carbon at a flowrate of approximately 2 1pm (liters per minute) representing typical conditions that existed a year ago. Comparison of the parts per million breakthrough versus time is shown in Table IM Dow Experimental Carbon (XF4175'L), Pittsburgh MSC-V14X40 mesh and Columbia Carbon showed the best break through characteristics; however, the Dow Ex perimental Carbon and the M>C-V are not commercially available at this time. Replicate samples of Columbia Carbon TS-570 were tested against those of Pittsburgh Loren W. Severs, received a 0.A. in chemistry from the University of California, Irvine in 1972, Joined The Dow Chemical Company, Analytical Laboratories, Midland, Michigan, after graduation. Worked on anal ysis of trace contaminants in water and air. Recently served as consultant to the Industrial Hygiene Laborstory to develop methods of collection and analysis of organic vapors In air. Lyman K. Skory graduated from Michigan State Univer sity In 1949 with a 8.S. de* gree in Chemistry and from Pennsylvania State Univer sity with an M,S. degree in Organic Chemistry and joined The Dow Chemical Company. Midland, Michi gan, In 1951. He is currently a Group Leader in the Dow Industrial Hygiene Labora tory, Midland, He works closely with OSHA and NIOSH in health standards programs and with Product Stewardship for Dow cus tomers. American Industrial Hygiene Association Journal 669 TABLE I Comparison In Parts par Million of Commarcial Carbons; 30 ML Bad Volume, 200 ppm Vinyl Chloride, 1.97 Ipm Flowrate FISHER. SCIENTIFIC WESTVACO COCOANUT COLUMBIA PITTSBURGH TIME NUCHAR WVH CARBON CARBON BPL DARCO (HOURS) 8x30 MESH 6x14 MESH SMALL MESH 4x10 MESH 4x12 MESH 0.5 <0.05 <0.05 <0.05 <0.05 <0.02 1.0 <0.05 <0.05 <0.05 0.24 <0.02 1.5 0.08 <0.05 <0.05 0.88 0.02 Z.0 0.53 0.21 <0.05 1.77 0.12 2.5 5.22 0.95 <0.05 -- 0.51 3.0 26.30 5.45 0.05 3.15 11.80 PITTSBURGH M$C*V 14x40 MESH <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 WITCO GRADE 360 10x20 MESH <2 2 4 4 12 40 OOW EXPERIMENTAL CARBON XF-4175L <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 T j PCB 12X30 Activated Carbon. The bed size Figure 2 shows that the breakthrough j was reduced to 1 gram of carbon contained in under these conditions is nearly 3% after 15 j a stainless steel tube (14 cm x 0.25" O.D. x minutes. The NIOSH method also states that 5 0.028" wall) fitted with Swagelok caps. The liters of 200 ppm vinyl chloride can be col ! test concentrations was reduced to 50 ppm lected at 0.05 lpm without significant amounts vinyl chloride and the pump flowrate was re of vinyl chloride being found on the back sec duced to 0.2 1pm. Table II shows the Pitts- tion. Duplicate test runs under these conditions > burgh PCB carbon to be the most suitable for showed that substantial breakthrough occurs : eight hour time-weighted average personnel well before 5 liters of sample has been collected sampling. The 1 gram slugs of PCB carbon (Figure 2). I were also tested at 25 ppm with flowrates of A direct comparison of the carbon in the ! 0.5 and 1.0 1pm. Table III gives the results of NIOSH recommended tubes and PCB 12X30 ! those tests. Based on these data, the following was made by repacking the NIOSH tube with sampling conditions were recommended for the 150 mg of PCB carbon and repeating the ex 1 gram slug of Pittsburgh PCB 12X30 Acti periment. Figure l shows that the two carbons vated Carbon: (1) 0.2 1pm for 8 hours, (2) 0.5 have similar breakthrough characteristics under lpm for 10 to 60 minutes, and (3) 1.0 1pm for these conditions. However, this may be due to 10 minutes. carbon bed size than type of carbon. The tubes Further breakthrough testing was con ducted with different sized tubes for short time periods. The NIOSH method for vinyl chloride in air1 uses a 150 mg divided charcoal tube. This charcoal tube was tested with 1 ppm and 5 ppm vinyl chloride at a flowrate of 1 lpm. Figure 1 shows breakthrough within the first minute and approximately 12% breakthrough after 10 minutes. The flowrate for this size could be used in a 5 ppm atmosphere at 0.05 lpm for 15 minute sampling; however, only 0.75 liter is collected. Even with a GC sensi tivity of 1 /ig/sample, a less than value of 0.52 ppm is obtained, which is above the action level (0.5 ppm) and much higher than the de sired 0.1 ppm sensitivity. We, therefore, con cluded that the 150 mg NIOSH recommended tube was inadequate for vinyl chloride sampling. tube was reduced to 0.2 lpm and the experi Two larger tubes of carbon were tested ment repeated at the 5 ppm level. under similar conditions. A 600 mg charcoal R&S 110367 TABLE II Parcent Breakthrough for Columbia and Pittsburgh PCB Activated Carbons at 50 ppm Vinyl Chloride and 0-2 Ipm Flowrate (HOURS) 5.0 5.5 6.0 6.5 7.0 7.5 COLUMBIA CARBON TS-57Q 1.0 2.5 12.0 24.0 46.0 -- PITTSBURGH PCB 12x30 <0.3 <0.3 <0.3 <0J <0J . <0-5 #70 TABLE III Percent Breakthrough for Ona Gram of Pittsburgh PCB 12x30 at 25 ppm Vinyl Chloride With 0.3 and 1 Ipm Flowrates TIME (HOURS) 1.0 1.25 1.7 1.8 2.5 2.9 3.3 3.6 0.5 LPM____________ 1.0 LPM < 0.06 -- < 0.06 <0-06 030 2-80 13.00 0.4 0.8 .---- -- Saptviabw, 1875 h. 22 20 600 mg commercial tube 4 25 ppm 18 700 mg PCB, 12x30, 16 50 ppm a 700 mg PCB, 12x30, 25 ppm " J 00 \* s .i 0 20 30 40 50 60 Figure 1-Vinyl chloride breakthrough. 150 mg tube at 11pm. Minute* Figure 3-Vinyl chloride breakthrough, 600 and 700 mg tubes at 1 Ipm. 8 9 5 ^ Figure 2-Vinyl chloride breakthrough, 150 mg tube Figure 4-Methyl chloride breakthrough, 100 ppm at reduced flowrates. at 0.2 Ipm for 150 and 600 mg tubes. tube is manufactured by the makers of the 150 mg NIOSH tube. A tube was also made from a disposable glass transfer pipette containing approximately 700 mg of the Pittsburgh PCB AmtricM Imfurtrtil HyflOM Auoclation Journal 12X30 Activated Carbon. Figure 3 shows the results for testing these tubes at 25 and 50 ppm vinyl chloride at 1 1pm. Either tube could be used for .the 15 minute sampling and at 571 reduced flowrates (0.2 or 0.1 lorn) for ex tended periods of time (7-8 hours) at these levels. Two items of interest are evident from Figures 1 and 3: (1) the breakthrough time and percentages are not directly proportional to those seen for the 150 mg tube, indicating ad ditional factors in adsorption (possibly tube dimension and/or a change of carbon), and (2) the breakthrough curves for 25 and 50 ppm are almost identical, as are those for 1 and 5 ppm on the 150 mg tube. These data indicate that the percentage breakthrough for a given flowrate and tube size is independent of the concentration for at least the 1-50 ppm range. Similar breakthrough testing was per formed for methyl chloride and vinylidene chloride. Methyl chloride was tested at 100 ppm (TLV) for various flowrates and tube sizes. Figure 4 shows 150 mg tubes are not suitable for methyl chloride sampling at the current allowable levels, although the PCB carbon appears to have better retention capa bilities. The 600 mg size tube might be used for short term samples. Reducing the flowrate below 0.2 1pm would increase the time of sampling. However, by using the 1 gram slug of PCB 12X30 and reducing the flowrate to 0.1 1pm, sampling times of up to 80-90 min utes are feasible (Figure 5). This figure also shows the increase in sampling time possible by decreasing the flowrate from 0.5 to 0.2 to 0.1 1pm. A sample test of 200 ppm at 0.2 1pm flowrate is also known for comparison. If methyl chloride and vinyl chloride are to be sampled in the same area, the methyl chloride will be the limiting factor in choosing a sampling period and flowrate. Only by increasing the amount of carbon and/ or greatly reducing the flowrate can eight hour sampling be attempted. (Methyl chloride breakthrough was also determined on the 1 gram slug of PCB 12X30 at the 50 ppm level. The breakthrough curves are the same as those shown in Figure 5 for 100 ppm. This further demonstrates that per centage breakthrough for a given flowrate and tube size is independent of concentration.) The breakthrough characteristics for vinylidene chloride are much less severe than for methyl chloride and vinyl chloride through out testing. Figure 6 shows that the 150 mg size tube may be used for short term samples(10*15 minutes) at 1 1pm. However, the PCB 12X30 carbon begins to show definite ad vantages over the carbon used in the com mercial tube. Reducing the flowrate will, of course, allow for longer sample times, but not long enough for eight hour samples. The 600 mg size tube has very good retention capability for vinylidene chloride. A test of 31 ppm vin ylidene chloride samples at 1 1pm showed less than 0.08% breakthrough after 75 minutes. Thus, with a reduction in flowrate to 0.1 or 0.2 1 pm, eight hour sampling is quite pos sible. (Tliese data suggest that the type of car bon has been changed in this size tube because a simitiar test run a year ago showed substantial breakthrough after 60 minutes. The 150 mg and 600 mg tubes were SKC Lot 104 and Lot 105, respectively. SKC has confirmed a Q0 J 20 i i i 410^--M *0 100 1201-*40 Mtnvtw 161 0 Figure 5-Methyl chloride breakthrough, 100 ppm at various flows for 1 gram Pittsburgh PCB 12X30 activated carbon. change of carbon between the two lots. This change in carbon was recommended to the supplier after NIOSH had received our recom mendations.) One gram of the PCB 12X30 carbon in a stainless steel slug has been run under these conditions-for eight hours with no detectable breakthrough. Carbon Disulfide Desorption A desorption technique for vinyl chloride was devised that would ensure the integrity of the sample. An experiment in one of our labora tories indicated a 98% recovery was obtained when the carbon was slowly added to the CS* cooled in a dry ice/acetone slurry.2 The follow ing procedure has since proven to be satisfac tory: (1) cool 10 ml of CSj to dry ice tempera ture; (2) slowly add the carbon to the cold CS* (3) agitate for 30 minutes, keeping cold; (4) *72 * ^ t * 4 refrigerate until analysis, analyzing from a wet ice bath. It was found that by thus minimizing the heat generation during desorption, replicate samples have given a recovery range of 93- 101%. This same desorption technique has been applied to samples of methyl chloride. Over a period of time, 25 known samples have shown a recovery range of 70-97% with an average of 83% dt8% (one standard deviation). The wide range of recovery values has not yet been accounted for. Desorption of vinylidene chloride samples is accomplished by the same procedure. A wet ice bath can be used, unless one or more of the low boiling gases are to be determined also. to Figure 6-Vinylidene chloride breakthrough, 20 ppm at 1 Ipm for 150 mg tube. Recoveries for vinylidene chloride in CS2 have a range of 95-100%. Standard Preparation A technique was adapted from a procedure used at Dow for many years.5 Vinyl chloride gas is condensed in a fared, narrow neck ampule in dry ice. The ampule is flame sealed and reweighed to constant weight. A small Swagelok nut is carefully placed over the neck of the ampule and the whole assembly gently lowered into a measured volume of Cf. The ampule is then broken by shaking the bottle. No bubbles of gas are seen during this operation, indicating that the vinyl chloride is completely dissolving in CSj. Methyl chloride standards can be made by following the same procedure. Standards of vinylidene chloride are rou tinely prepared by injecting a measured volume of vinylidene chloride into a known volume of CSi with a microliter syringe. There was some question about standards made by injecting a known volume of gas into a known volume of CSa in a sealed serum vial at room temperature and wet ice temperature so the above technique was utilized. Condens ing the vinyl chloride in dry ice and using a 10 ml glass syringe cooled to dry ice temperature to prepare a standard proved difficult to duplicate. Sample Storage The flood of inquiries from industrial hygienists, both from industry and government regarding personnel samples taken at one location and forwarding to a laboratory at another location for analysis, set the priority for determining sample storage characteristics. The backlog of samples taken in our own company and limita tions of available manpower and instrumenta tion further substantiated the need to know how much absorbed vapor was being lost during storage or shipment of carbon tubes. Sample of 10 liters of vinyl chloride at 1 ppm on the PCB 12X30 activated carbon were stored in polyethylene tubing for one to three weeks; 10 to 20% loss was noted with increased storage time. The effects of four weeks storage at room temperature were checked with both the stainless steel and glass tubes, and no apparent sample degradation was observed. However, it was found that if samples were removed-from their tubes and placed in small vials sealed with Polyseal caps, up to 40% of the initially loaded vinyl chloride was lost after one week of storage in the freezer. Samples, therefore, should be kept sealed in the original sample tubes until desorbed. The storage effects on vinylidene chloride in glass tubes proved to be within the error * (5%) of the analytical method. Effects on methyl chloride samples have not yet been determined. Thermal Desorption Thermal desorption was investigated as an alternate to CS* desorption. Thermal desorp tion, if perfected, offers several advtanges over carbon desorption, such as reduced health hazards. AftMrfCM ffttfaftrttl Hyflffl* *od*t<w Jonmtl 573 1 R&S 110370 % R&s 110371 The experimental apparatus consist of recovery of 88% 5% (one standard devia gas source, a dry test meter for measuring gas tion) when desorbed with 10 liters of nitrogen. volumes, a muffle furnace and a Saran* film | bag to collect the expelled vapors. The inlet Analytical Condition* and outlet tubes are of stainless steel as are Analysis is performed by gas chromatography/ j the sample tubes. Prepurified nitrogen at a flame ionization detection. No one column or i flowrate of 500-800 ml/minute is used as the set of conditions can cover all situations in ; purge gas. Hie oven temperature was initially volving analysis for vinyl chloride. A variety j set at 225C, however, the low and erratic of columns have been used depending upon j recoveries obtained were eliminated by raising the situation. Figures 7-11 show some of the the temperature to 430C. columns that can be used under varying cir The desorption procedure is as follows. cumstances. 1 Place a 10 liter Saran film bag at the exit end Breakthrough was determined by period | of the outlet tube; connect the sample tube in ically injecting air samples drawn from a glass j the line and start the nitrogen flow. Purge the tee placed behind the carbon tube. The follow ' system with approximately 1 liter of nitrogen ing GC conditions were employed. before placing the tube in the furnace. After Column: 6' x Ya " stainless steel 20% placing the tube in the furnace, collect the DC 200 on Chromosorb W, ; . expelled vapors until the desired volume is 80/100 Mesh obtained. Divert the nitrogen flow from the Column collection bag and remove the bag for analysis. Temperature: 80C For samples of approximately 100 liters Carrier Flow: 30 ral/rain Nj of 50 ppm vinyl chloride, 4 liters of nitrogen Hydrogen \ were sufficient to obtain recoveries of 97% Flow: 30 ml/rain 4%. The same was true for 100 liters of 10 240 ml/min ppm. However, for short term samples, e.g., Detector 10 liters collected at 11pm, it was found that Temperature: 250C more nitrogen was needed. At 25 ppm, 4 liters Sample Size: 0.5 cc with GSV, or 1.0 ml of nitrogen gave 90% recovery. At the 10 Pressure-Lok Syringe ppm level, 10 liters of nitrogen had to be used to obtain 93% recovery and at 1 ppm, 12 liters Sample analysis was originally performed of nitrogen were needed to obtain this recovery. on this same column at 40C. Both vinyl Fifteen replicate samples of 1 ppm vinyl-chlo chloride and vinylidene chloride can be deter ride were analyzed by this method. The aver mined (Figure 7); however, light hydrocarbons age recovery was 92% 3.5% (one standard may interfere with the vinyl chloride determi - deviation). Subsequent series of tests have nation. Such interferences were eliminated by shown a recovery factor of 80% 5%. At employing the following conditions (Figures tempts were made to find the cause of the 8 and 9). decrease. Neither the use of glass tubing nor deactivated and conditioned stainless steel tub ing increased the recovery factor to its original value. Replacement of the inlet/outlet tubing and the nitrogen supply has had the same nega tive effect. Although this new factor is lower than what was originally found, it has been reproducible and could, therefore, be effectively used as the recovery factor for this technique. Column: Column Temperature: Injection Port: Sample Size: 20' x Vfc" stainless steel Carbowax 4000 on Supelcoport 80/100 Mesh 80C Unheated, on-column injection 2 microliters The recoveries of methyl chloride and vinylidene chloride have also been determined by this technique. A recovery of 75% 5% is obtained (one standard deviation) for 6 liters of both 50 and 100 ppm methyl chloride desorbed with 10 liters of nitrogen. Replicate samples of 10 ppm vinylidene chloride gave a Other parameters were the same as pre viously stated. Temperature and carrier flow are quite critical because the vinylidene chlo ride is not completely separate from the CSi; "Sana U ft trmdcmftrfc of Tb* Dow Qwmkftl Company abroad. 674 Conclusions When the vinyl chloride situation arose it was found that existing techniques for personnel sampling and analysis of vinyl chloride expo sures were found to be inadequate because vinyl chloride vapor was easily lost from the sample at several different stages in the collec tion and analysis. This study evaluated numerous adsorbing media and found that one specific cocoanut carbon, Pittsburgh PCB 12X30 Activated Carbon, is the most suitable of the commer cially available carbons tested for personnel sampling of vinyl chloride and related com pounds. One gram of this carbon packed in a stainless steel tube (14 cm x 0.25" O.D. x 0.028" wall) can be used satisfactorily to col lect vinyl chloride, vinylidene chloride and methyl chloride according to the sampling conditions developed herein. The study devel oped improved techniques of desorbing the carbon using CSi at dry ice temperature. Thermal desorption was also investigated as an alternative to CSj desorption. Minutas Acknowledgement The authors wish to express their thanks to A. A. Allemang, R. A. Dommer, R. K. Lee, G. J. Roush and G.E. Socha for their assistance in this study. Figure 7-Chromatogram of components on DC 200 column; (1) vinyl chloride, (2) vinylidene chloride, (3) CS5 R&S 110372 small changes in either of these parameters results in loss of resolution. These conditions have proved satisfactory except for samples containing methyl chloride, dichlorodifluoromethane and/or dimethyl ether in addition to vinyl chloride. For these situations satisfactory separations have been achieved under the following conditions (Fig ures 10 and 11). Column: Carrier Flow: Column Temperature: 5'xVi" stainless steel Porapak QS, 80/100 Mesh 40 ml/min Nj 70C (methyl chloride, dichlo rodifluoromethane, vinyl chloride) 115C (methyl chloride, di methyl ether, vinyl chloride) Figure 3-Chromatograms of components in air on Carbowax 4000 column; (1) isobutane, (2) vinyl chloride, (3) vinylidene chloride, (4) trans-l, 2-dichloroethylene, (5) methacrylonitrile, (6) acrylonitrile. Amarlcan Induttrial Hytfana Aaaoeiation Journal 67S 23 i t I Figure 10-Chromatogram of methyl chloride and vinyl chloride In the presence of Freon12 on Porapak QS column; (1) methyl chloride, (2) Freon-12, (3) vinyl chloride. Minutes . Figure 9-Chromatogram of components In CSZ on Carbowax 4000 column; (1) vinyl chlo ride, (3) CS2. References 1. Federal Register 39;194, October 4, 1974. 2. Private communication, A. A. Allemang. 3. Private communication, R. K. Lee. 4. Vinyl Chloride in Air, NIOSH Analytical Method. 5. Stenger, V. A., S. A. Shrader and A. W. Beshgetoor; Analytical methods for methy bromide. Ind. & Chem. (Anal. Ed.) 77*121 (March 15, 1939). r0- I "T I o 10 12 14 Time. Min. Figure 11-Chromatogram of methyl chloride and vinyl chloride in presence of dimethyl ether on Porapak QS columns; (1) methyl chloride, (2) dimethyl ether, (3) vinyl chloride. 676 September, 1975 R&S 110373