Document jmLKZBEOaYkOddDxKz0gaoLr2

High-volume Collection of Atmospheric Polychlorinated Biphenyls by T. F. Bioi.c.m a.' and C. E. Olnet Dvpartment of Food and Kenource CAtmiilry University of Rhode Island, Kingston, RJ. 02H8I I1 The atmosphere has been suggested as a major transport rout* of chlorinated pesticides and polychlorinated biphenyls (PCB) to the oceans (RISEBROUGH et al. 1968, WOODWELL et al. 1971, SEBA and PROSPERO 1971, N1SBET and SAR0F1M 1972), but only a few measurements of organochlorines in the marine atmosphere have actually been made. A barrier to obtaining this much-needed Information has been the lack of suitable collection methods. The conaaon approaches to sampling airborne pesticides are columns packed with solid adsorbents, lmplngers, and gas bubblers (YULE et al. 1971, MILES et al. 1970, STANLEY et al. 1971, THOMPSON 1971). Many of these methods were developed for use in agricul tural areas or to monitor insecticide drift during forest spray ing operations where concentrations of insecticide In the atmosphere are apt to be high and the volume of air required for a sample relatively smell, on the order of 5 - 50 cubic meters. The lower levels of chlorinated hydrocarbons expected la the marine atmosphere require that hundreds or even thousands of cubic meters of air be sampled, necessitating high volume collec tion equipment. One approach to DDT collection over the ocean has been to hang nylon screens coated with an organic liquid in the wind to trap particulate matter (RISEBROUCH et al. 1968. SEBA and PR0SPER0 1971). Several million cubic meters of air were sampled, but the collection efficiency of these screens for gaseous organochlorines is unknown and it has been suggested that PCB ara likely to exist in the atmosphere as vapors rather than adsorbed on particles. This paper reports an efficient collection system for PCB vapors that allows hundreds of cubic meters of sir to be saapled per day. The trap is a plug of porous polyurethane foam, a sub stance that has been used to extract FCB from seawater (GESSEK et al. 1971). The foam offers little resistance to air passage and therefore is compatible with high-volume sampling apparatus. Experimental The PCB Isomers 3,A^'-trichlorobiphenyl (tri), 2,5,2*,5'tetrachlorobiphenyl (tetra), and 2,4,5,2',S'-peatachlorobiphenyL (penta) were obtained from Analabs Inc., North Haven, Conn. 06473. KQt*s foil runt. (kh) i.i . SCbA few hllvr '(!(] hndii. cuius (YIM.l IMPRON URrjtui t Kpr.iv- jllcd fot ptelcm. the oi colic,- orr.'in buiil in P<*B, all [renn lot ted th.it r than [it PC nanpJc.i a Ruh* jessik >asv^r' ,anu u'. 2*, V* Jplipnv 1 n. <>*-'' ft'^roclor J24S and 1254 analytical standards were supplied by the 3.feticides Repository of the Perrine Primate Research Branch, ^Environmental Protection Agency (EPA), Perrine, Fla. 33157. Sol- vents were Malllnckrodt Nanograde petroleum ether and dichloroaethane, B & A ACS reagent grade acetone, and Eastman ethylene glycol. Adsorbents for column chromatography were Woelm neutral alumina and Malllnckrodt 100-mesh silicic acid. Gelman glass fiber A (GFA) filters were wrapped In aluminum foil and baked at 450C for 4 hours to remove organic matter. High-volume air samples were collected with a Gelman Hurricane Air Sampler, Model 16003. A small 1/6-hp air pump was used to draw air through the 'lapingcr for lcn-volume sampling. Circular plugs 4 Inches in diameter were cut from 2-lnch ^polyurethane foam (density 0.021 g/cm3). New plugs were washed 4 by squeezing under running tap water and rinsed with acetone. J'The plugs were then extracted for 12 hours with acatone followed Kby 12 hours with petroleum ether in soxhlet extractors large j enough to hold 6 plugs. One batch of tha solvents was used to gtelean 18 - 24 plugs. The extracted plugs were rinsed with a all volume of fresh petroleum ether, squeezed as dry as pos sible, and the residual solvent was removed by gentle heating. a large vacuum desiccator heated to 40*C with heating tape SDd Reconnected to a water aspirator was convenient for drying the (plugs with a minimum of atmospheric contamination. Air was re admitted to the desiccator through a column packed with clean foam. Plugs for sample collection were squeezed dry after ex traction of the sample, rinsed with petroleum ether, dried as (above, and reused for subsequent sampling. Clean plugs and [^samples were stored In wlde-raouth mason jars with aluminum foil ^between the Jar and cap. For high-volume air sampling two foam plugs were inserted Plato a 3-1/2-inch diameter aluminum cylinder, taking care to (avoid empty spaces between the plugs and cylinder wall. The " ylioder was attached to the rear of a stainless steel filter (Older containing an 8" x 10 GFA filter and the filtering ap paratus was connected to the Hurricane pump through 10 feet or ore ol flexible hose. Collections were also made with a Greenrg-Smlth lapinger charged with 100 ml ethylene glycol and ^backed up by a column packed with polyurethane foam. A small FA filter placed over the entrance to the lapinger ensured that mly vapors were sampled. Glass beads coated with the compounds f Interest served as known sources of atmospheric PCB. The ^btads were placed e few Inches to several feet from the collec tion device, thus regulating the levels in the air being sampled. After sampling had been completed, the GFA filters were cut (Into strips and refluxed for 2 hours with 150 ml petroleum ether ' ` the foam plugs were extracted for 2 hours (30 cycles) In I fl^freoahlct extractors with 175 ml petroleum ether. The extracts ' '?hf-vere concentrated to a small volume by evaporation under reduced * Pressure or In a Kudema-Danish apparatus and cleaned up by 'T.''alumina or silicic acid column chromatography. In the former HONS 065740 procedure. 4 g activity grade III alumina (prepared by adding 6?. water to activity grade I alumina) was slurried with petroleum ether and packed into a 1-cra diameter column. The sample was traosferred to the column and eluted with petroleum ether. The flrat 3 ml of eluate was discarded; the next 8 ml containing the PCB was collected and adjusted to a suitable volume. The silicic acid procedure used waa a modification of that reported by ARMOUR and BURKE (1970), and was carried out with a 3-g colunxt of de activated (3.3% water) silicic acid, using 50 ml petroleum ether and 10 ml dichloroaethane to elute the PCB and DDT fractions respecclvaly. Extracts were analyzed with a Tracor Microtek 220 gao chromatograph equipped with two columns, two *^N1 electron capture detectors, and a dual-channel recorder. Columns were 1.5X OV-1// 1.95Z QF-1 on 100/120-mesh Supelcoport (coluam A) and 4% SE-30/ 6Z QF-1 on 80/100-mesh Supelcoport (coluon B). Instrumental con ditions: nitrogen carrier gas. coluon temp. 200*C, detector temp. 350*C. flow rates 74 ml/min (coluon A) and 100 ml/mtn (coluam B). Peak heights of sample chromatograms were compered to those of Standards. Quantltstion of Aroclora in the atmospherlc samples from Bermuda was based on the sum of the heights of the peaks in the sample that matched Aroclor 1248 or 1254 standards. Results and Discussion Extracts of polyurethane foam showed two major GC peaks (Fig. 1). These were obtained even after the plugs had been extracted several times and were assumed to come from the foam itself. Alumina chromatography removed the compounds responsible for these two peaks. Alternatively, If the sample was separated into F'CB and DDT fractions on silicic acid these peaks ware found in the DDT fraction and thus did not Interfere with the PCB determination. The blank range for 7 plugs waa 7 - 27 ng (mean 15 ng) as Aroclor 1248. * Collection studies with PCB Isomers on GFA filters and poly urethane foam plugs were conducted outdoors with sampling periods varying from 12 - 34 hours and the temperature range approximately 5 - 20*0. Table 1 shows the excellent collection efficiency of the foam plugs for til-, tetra-, and pentachloroblphanyl iaomera. Cooperative runs were made with a Greenburg-Smith Implnger con taining athylena glycol, the system used by EPA for sampling airborne pesticides (THOMPSON 1971). The collection efficiency of the implnger for PCB vapors (Table 2) is lower than for the foam plugs and is approximately the same as reported by MILES et al. (1970) for organophosphorus insecticide vapors. Implngers are not the preferred method for sampling marine air because they are limited to relatively low flow rates. Atmospheric samples were collected during February - March 1973 from the top of a 20-meter tower at High Point, Bermuda, with 0851"* HONS A \ ^ '/ 1 co M HONS 0 8 5 7 4 3 Collection of PCB Vapors on Polyurethane Foam Plugs Flow Rate m3/rain 0.48 0.50 G.62 0.68 0.76 Volume sir m3 987 683 865 958 550 PCB in air,a ng/n3 tri tetra penta - - 5.6 1.2 2.3 2.4 0.86 - - 2.4 0.47 - - 0.4 0.14 1.7 - - -- tri -- 99 --- 99 first PF plug6 tetra penta 99 96 99 98 99 97 98 96 -- -- ^Calculated from volume of air sampled and quantity of PCB trapped. 1Z or less of total PCS was found on the second plug In all cases. X on GFA filter tri tetra penta - - 0.7 4 0.4 0.6 2 - - " 0.5 2 - - 1.0 3 0.3 - - - - tHtr higli-vol nmp equipment described. Wind direction was monitored with a recording anemometer. Samples 1-4 were collected with out regard to wind direction while 5 and 6 were collected inter mittently only while the wind blew from the open-ocean sector (90 - 240*). The GC patterns matched Aroclor 1248 (Fig. 2) and the concentrations in the air were calculated as both Aroclor 1248 and 1254 (Table 3). Most of the PCB was found ou the first foam plug of the two inserted Into the cylinder. Even for MamplttH 5 and 6, which remained on the towor for a week, the collection efficiency of the first plug was approximately 80%. Negligible fractions of total FOB (< 2%) were found on Che GFA filters In all cases, in agreement with the results in Table 1. Glass fiber filters are commonly used to collect high-volume particulate samples and have been shown to be efficient collec tors of DDT dusts and some organophoaphorus insecticide vapors under low-flow conditions (MILES et al. 1970). This study shows that they arc poor collectors for PCB vapors during high-volume sampling, but the CFA filters appear to have a slightly higher collection efficiency for the less volatile pentachlorobiphenyl than for the trl- or tctTachlorobiphenyls (Table 1). Preliminary experiments Indicate that polyurethane foam plugs are also good collectors for atmospheric DDT and the extension of this method to chlorinated pesticides, phthalate esters, and hydrocarbons is currently under investigation. Acknowledgement a Tills work was supported by the Office of the International Decade ol Ocean Exploration, National Science Foundation, under NSF grant CX-33777. Contribution No. 1486 of the Rhode Island Experiment Station.