2226
Anal. Chem. 1983, 55. 2226-2228
(19) Johnson, D.C.J . Electrochem. SOC. 1972, 119, 331. (20) Hubbard, A. T.; Osteryoung, R. A.; Anson, F. C. Anal. Chem. 1966, 38,692.
RECEIVED for review July 1, 1983.
Accepted September 12,
1983. Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. This work was supported by the Office of .. Basic Energy Sciences.
Membrane Filters as Adsorbents for Polynuclear Aromatic Hydrocarbons during High-Volume Sampling of Air Particulate Matter Torsten Spitzer*' Environmental, Industrial and Food Analysis, Leipziger Strasse 68, 3330 Helmstedt, German Federal Republic
Walter Dannecker Institut fur Anorganische Chemie, Martin-Luther-King-Platz6,2000 Hamburg 13, German Federal Republic
Urban air particulate matter is sampled by the high-volume method wlth glass fiber filters and membrane filters. Polynuclear aromatic hydrocarbons are then determined by cleanup on XAD-2 and glass caplllary gas chromatography. It Is found that membrane fllters retain polynuclear aromatlc hydrocarbons wlth three and four fused benzene rings more efficiently than glass fiber filters. The rapid blow-off of phenanthrene and pyrene from glass flber fllters is demonstrated. Membrane filters can also adsorb vaporized PNA.
The monitoring of polynuclear aromatic hydrocarbons in air is of considerable importance due to the carcinogenic properties of this class of compounds. In the past, glass fiber filters have been the material of choice for both high-volume and low-volume sampling (I, 2). High-volume sampling with glass fiber filters cannot avoid losses of polynuclear aromatic hydrocarbons with three or four fused rings, which can be quite substantial (3). This deficiency of glass fiber filters was recognized some time ago, and the decomposition of benzo[alpyrene on the filter was also observed (4-6). Membrane filters are thought to be less suitable for sampling of polynuclear aromatic hydrocarbons due to their higher content of soluble organic material, which is coextracted with polynuclear aromatic hydrocarbons during analysis. If polynuclear aromatic hydrocarbons are isolated by cleanup on XAD-2 (7) after sampling and analyzed by glass capillary gas chromatography, no interference from the m,embrane fiiter can be observed. In this work both membrane filters and glass fiber filters are employed in the sampling of polynuclear aromatic hydrocarbons from the air, and their collection efficiencies are compared.
EXPERIMENTAL SECTION Cellulose acetate membrane filters with 260 mm diameter and a pore size of 1.2 pm were used (type ST 69, Schleicher + Schull, Dassel, GFR). These were dried at 120 "C immediately before use, which reduced their diameter to 257 mm. Glass fiber filters (257 mm diameter, type 6, Schleicher + Schull) quantitatively retained all airborne dust, since no particulate matter could be Present address: Nagoya Daigaku Ryugakusei Kaikan, 2-23 Tosei-cho, Showa-ku, Nagoya 466, Japan.
detected on a back-up membrane filter (type ST 69,l.z ,.tmpore size). Another type of glass fiber fiiter (type 8, Schleicher + Schull, Dassel, GFR) retained 97-98% of the airborne dust under the selected sampling conditions, while 2-3% of the total particulate matter was found on a backup membrane filter (type ST 69,1.2 bm pore size). Glass fiber filters used in this work had collection efficiencies of 99% (type 8) or 99.97% (type 6) for oil aerosol with a particle size of less than 1.0 pm (8). Air flow rates were adjusted to 50 m3/h with high-volume samplers (HVS-1, Stroehlein instruments, Dusseldorf, GFR). Two filter heads were mounted on frames 1.5 m above the ground and placed 80 cm apart. Particulate matter was collected simultaneously by using a membrane filter on one sampling head and a glass fiber filter on the other. Mean sampling temperatures were 8-15 "C. The sampling site was situated in an urban area. Main roads carrying heavy traffic, residential areas, and a coal-fired power station were located within a radius of 1km from the sampling site. Loaded filters were dried over silica gel (5 h) and extracted with toluene (Soxhlet, 4 h) after weighing. Polynuclear aromatic hydrocarbons were isolated by cleanup on XAD-2 (7) and determined by gas chromatography with capillary columns and splitless injection. The columns employed were drawn from Duran 50 borosilicate glass. They were leached at 180 "C with 20% HC1 for 8 h and rinsed successively with one column volume of water and methanol immediately afterward. They were dried under a stream of nitrogen at 250 "C and deactivated by high-temperature silylation with diphenyltetramethyldisilazane (9). They were then coated statically (IO)with Dexsil3OO,OV-l, and SE-54 stationary phases. The instruments used were Carlo Erba 2400 and 2150 capillary gas chromatographs. Hydrogen was employed as the carrier gas. The detector system was an FID.
RESULTS AND DISCUSSION Simultaneous air sampling with a glass fiber filter followed by a membrane filter and with just a membrane filter was carried out for 30 h and 72 h in a series of experiments. Total particulate matter on the glass fiber filters and membrane filters differed by only 5% at maximum. Polynuclear aromatic hydrocarbons with three or four fused rings were found in much larger amounts on the membrane filters than on the glass fiber fiiters. Table I lists results typical of those obtained by high-volume air sampling for 72 h. The smaller amount of benzo[a]pyrene found on the glass fiber filter is not due to its volatility but may be a result of decomposition during sampling. Membrane filters succeeding glass fiber fiiters contained substantial amounts of polynuclear aromatic hydrocarbons from phenanthrene to chrysene,
0003-2700/83/0355-2226$01.50/00 1983 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 55, NO. 14, DECEMBER 1983
2227
1 I
30
d
d
ib
1
Ib min
Figure 2. Gas chromatogram of PNA adsorbed on a membrane filter 26
after sampling 23 m3 of air: column, 20 m X 0.35 mm; stationary phase, OV-25; splitless injection at 290 OC; temperature program, 100-260 OC; carrier gas hydrogen; detector, FID. Peak assignments are as follows: peak 26a, benzo[b]fluoranthene; peak 26b, benzo[jlfluoranthene; for remainlng peaks see Figure l.
I
AFTER
BEFORE
1 2
. - M F - - -- - - -
0
4
5-2
0
6
9-v
.----GF---
OPg P Y , O P g A n 3 + 5 0 P 3 P Y t A n
- ._ j_ ~_ . _..
0
... ..GF .-..
0
-MF- - - . -1 -----GF---
0
Flgure 3. Placement of membrane filters (MF) and glass tlber filters (GF) in a high-volume filter head for investigation of vaporization of polynuclear aromatic hydrocarbons during sampling (pV = pyrene, An = anthracene).
0
'
d
d
ab
ib
il n
Flgure 1. Gas chromatogram of polynuclear aromatic hydrocarbons isolated from alr particulate matter obtained after simultaneous sampiing with glass fiber (lb) and membrane filter (la): column, glass capillary 40 m X 0.3 mm, coated with OV-1; instrument, Carlo Erba 2101 capillary gas chromatograph: Injection, splkless at 300 O C ; carrier gas, hydrogen; temperature program, 100-280 OC, 4 OC/min. The peak assignments In Figure IC are polynuclear aromatlc hydrocarbons found on the membrane filter succeeding the glass fiber fllter used In Figure ib: (1) phenanthrene, (2) anthracene, (1 1) fluoranthene, (13) pyrene, (16) benzo[a]fluorene, (17) benzo[b]fluorene, (19) benzo[b]naphtho[2, l-dlthiophene, (20) benzo[gh/]fiuoranthene, (21) benzo[c]phenanthrene, (22) cyclopenta[cd]pyrene, (23) benz[a]anthracene, (24) chrysene triphenylene, (26) benzo[b]fluoranthene benzo[j]fluoranthene, (27) benzo[k]fluoranthene, (29) benzo[e]pyrene (30) benzo[a]pyrene, (31) indeno[ 1,2,3-cd]pyrene, (32) benro[ghi]perylene, (35)coronene.
+
+
whereas heavy polynuclear aromatic hydrocarbons were absent. This is demonstrated in Figure 1. After 30 h of high-volume sampling it was also found that the glass fiber filter retained much smaller amounts of PNA with three and four fused benzene rings than the membrane filter. Unexpectedly, the difference between the two filters after this shorter sampling period was almost as big as the difference between the two filters found after the longer
sampling period of 72 h. Accordingly, values listed in Table I for the longer sampling period are also valid for the shorter sampling period of 30 h. A comparison between different sampling periods or different sampling experiments is extremely difficult. Parameters like the sampling temperature and concentration and nature of total particulate matter exert an influence upon collection efficiencies for vaporized PNA. Furthermore, reactive trace components of air, notably NO, and ozone, which can react with PNA on the filter material during sampling, are normally present at different concentrations between different sets of sampling experiments. Prolonged sampling with membrane filters also leads to inevitable losses of polynuclear aromatic hydrocarbons with molecular weights between 178 and 202. This is indicated by the fact that the amount of three- and four-ring PNA on a glass fiber filter and a membrane filter located downstream behind the glass fiber filter exceeds the amount of these compounds on a single membrane filter (Table I). This blow-off from membrane filters is poorly reproducible and depends on a number of parameters, some of which are sampling temperature, sampling time, and total particulate deposition on the filter. Quantitative sampling of vaporized polynuclear aromatic hydrocarbons can only be performed over short sampling periods with several membrane filters in series. Best results were achieved with filters of cellulose acetate dried immediately before use. Sampling of particulate matter with membrane filters over short periods of time gives profiles of polynuclear aromatic hydrocarbons containing phenanthrene, fluoranthene, and pyrene in a large excess over the
2228
ANALYTICAL CHEMISTRY, VOL. 55, NO. 14, DECEMBER 1983
Table I. Simultaneous Sampling of Polynuclear Aromatic Hydrocarbons from Ambient Air with Glass Fiber and Membrane Filtersa
phenanthrene fluoranthene pyrene chrysene benzo[ blfluoranthene + benzo~lfluoranthene benzo[e]pyrene benzo [a]pyrene benzo[ghi]perylene
amt on GF,* %
amt on back up MF,* %
7-14 20-29 23-42 62-87 89-102
96-215 1 37-1 72 112-143 10-30 0
100 0 79-100 0 88-107 0 ' Data base on three sampling experiments ( n = 3). Amounts on glass fiber (GF) and backup membrane filter (MF) as a percentage of the amounts found on a single membrane filter used simultaneously. Presuming no losses by volatilization or decomposition, the amount of benzo[e]pyrene was set equal to 100% and assumed to be equal on the membrane filter (MF) and the glass fiber filter (GF).
-
Table 11. Recoveries of Polynuclear Aromatic Hydrocarbons from Membrane Filters and Glass Fiber Filters by Soxhlet Extraction with Toluene %
%
amount, recovery recovery pg GF' MFa phenanthrene anthracene pyrene benzo[ blfluorene chrysene benzo[e]p yrene benzo[a]p yrene perylene benzo[ghi]perylene coronene
14.1 9.8 2.8 3.0 5.6 3.5 2.0 5.8 9.8 2.3
93 85 90 93 91 83 77 69 88 97
86 69 86 98 89 95 76 70 89 90
a GF = glass fiber filter, MF = membrane filter, one filter of each type analyzed ( n = 1).
heavier polynuclear aromatic hydrocarbons (Figure 2). Figure 3 demonstrates a filter sequence used in sampling over short periods to investigate blow-off from glass fiber filters and adsorption of vaporized polynuclear aromatic hydrocarbons on membrane filters. Filter 3 (Figure 3) was spiked with 50 pg of pyrene and 50 pg of anthracene. Both compounds had disappeared from the filter after sampling 250 m3 of air within 5 h. Filter 5 (Figure 3)) however, adsorbed 20% of the total vaporized pyrene and 4% of the total vaporized anthracene. The sampling temperature was 18 "C. The remaining pyrene and anthracene obviously were lost by vaporization or decomposition. Small amounts of phenanthrene and fluoranthene were detected on filter 5. These compounds originated from the ambient air and passed through the first membrane filter without adsorption. This experiment demonstrates the poor adsorption capacity of membrane filters for anthracene and pyrene. I t can be assumed that the adsorption capacity for isomeric three- and four-ring PNA is similarly low. Recoveries of polynuclear aromatic hydrocarbons from membrane filters and glass fiber filters by Soxhlet extraction are equally high (Table 11). Filters were spiked with ten selected polynuclear aromatic hydrocarbons and extracted with toluene for 4 h, using a Soxhlet apparatus. Determination was carried out by cleanup on XAD-2 and glass capillary gas chromatography using splitless injection and n-dotriacontan as an internal standard.
Table 111. Standard Deviation after Quantitative Analysis of Four Identical Samples of Urban Air Particulate Matter for PNA amount, phenanthrene anthracene fluoranthene pyrene benzo [ghi]flu or an thene cyclopenta[ cdlpyrene chrysene + triphenylene benz [alanthracene benzo [b] fluoranthene benzorjlfluoranthene + benio-[klfluoran thene benzo[e]pyrene a benzo[a]pyrene indeno [l,2,3-cd]pyrene benzo[ghi]perylene coronene
!-%
%std dev
0.85 0.091 4.1 4.0 1.2 0.36 2.4 1.4 1.2 1.3
8.8 22 7 8.3 6.7 6.1 3.9 3.9 4.5 7.7
1.5 1.3 0.51 0.65 0.15
1.3 9.2 12.2 5.3
b
' Assuming no losses by evaporation and decomposition during sampling and analysis, benzo [elpyrene was used as a reference in calculating quantitative data for the other PNA. Quantitative determination of benzo[e]pyrene was performed with n-dotriacontane added after cleanup as an internal standard. Reference compound.
*
The standard deviation of the analytical method used in this work was determined by analysis of four identical samples of air particulate matter. The samples were off-cuts from a glass fiber filter, loaded evenly with particulate matter. Results are listed in Table 111. Recoveries of PNA from bare filter materials (Table 11) can be quite different from recoveries obtained from loaded filters. The analyses of four identical pieces of particulate loaded filter materials (Table 111) suggest that the recovery of PNA was identical in each of the four experiments, as can be concluded from the low standard deviations observed. The same recoveries were found after a longer extraction period of 1 2 h.
CONCLUSION Membrane filters employed in high-volume sampling of air particulate matter quantitatively adsorb chrysene and heavier PNA. Complete adsorption of polynuclear aromatic hydrocarbons in the molecular weight range 178-202 is difficult to achieve even over short sampling periods. Registry No. Phenanthrene, 85-01-8;anthracene, 120-12-7; fluoranthene, 206-44-0;pyrene, 129-00-0;benzo[ghi]fluoranthene, 203-12-3; cyclopenta[cd]pyrene, 27208-37-3;chrysene, 218-01-9; benz[a]anthracene, 56-55-3; benzo[b]fluoranthene, 205-99-2; benzoplfluoranthene, 205-82-3; benzo[k]fluoranthene, 207-08-9; benzo[e]pyrene, 192-97-2; benzo[a]pyrene, 50-32-8; indeno[ 1,2,3-cd]pyrene,193-39-5;benzo[ghi]perylene,191-24-2;coronene, 191-07-1; triphenylene, 217-59-4; cellulose acetate, 9004-35-7.
LITERATURE CITED (1) Tomingas, R.; Voltmer, 0. Staub-Reinhait. Luff 1978, 38, 216. (2) Grimmer, G.; Naujack. K. W.; Schneider D. J. Environ. Anal. Chem. 1981, 10, 265. (3) Konlg, J.; Funcke, W.; Balfanz, E.; Grosch, B.; Pott, F. Atmos. Environ. 1980, 14, 609. (4) Wiest, F. D.; Rondia, D. Atmos. Environ. 1978, 10, 487. (5) Peters, J.; Seifert, B. Atmos. Environ. 1980, 14, 117. (6) Pitts, James N., Jr.; van Cauwenberghe, Karl A,; Grosjean, Daniel; Schmid, Joachim P.; Fitz, Dennis R.; Belser, William L., Jr.; Knudson. Gregory B.; Hyds, Paul M. Science 1978. 202, 515. (7) Spitzer, T. J. Chromatogr. 1982, 237, 273. (8) Staubforschungslnstitutdes Hauptverbandes der gewerblichen Berufsgenossenschaft e.V., Bonn; Prufbericht Nr. 43504-02 172 und Nr. 43504-00 172. (9) Grob, K.; Grob, G.; Blum, W.; Walther, W.J. Chromatogr. 1982, 244, 185. (10) Bouche, J.: Verzele, M. J. Gas Chromatogr. 1968, 6 , 501.
RECEIVED for review January 27, 1983. Resubmitted July 21, 1983. Accepted August 8, 1983.
