Characterlzation of Aza Heterocyclic Hydrocarbons in Urban Atmospheric Particulate Matter Tsuneyukl Yamauchl" and Takashl Handa Department of Chemistry, Faculty of Science, Science University of Tokyo, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162, Japan
w h a heterocyclic hydrocarbons (AHHs) present in urban atmospheric particulate matter have been analyzed by high-performance liquid chromatography (HPLC) coupled with on-line fluorescence detection after a preseparation of the AHH fraction by one-dimensional dual-band thinlayer chromatography. Efficient preseparation and a significant increase in sensitivity over other methods were achieved. The HPLC fraction was identified by comparison of retention times and fluorescence emission spectra of individual components with data for authentic samples and also by the method of standard addition. These techniques were applied to the organic material present in the atmospheric particulate matter collected in the Tokyo metropolis. The concentrations [pg/g of particulates (ng/m3)] of identified AHHs (4-azafluorene, acridine, benz[a]acridine, dibenz[a,h]acridine, dibenz[aj]acridine, dibenz[a,c]acridine,and 10-azabenzo[a]pyrene)were at the to 3 X lO-l), and these to 3.5 (3 X levels of 3 X were about 10-1000 times lower than those of major polycyclic aromatic hydrocarbons. Moreover, the concentrations generally decreased with increasing ring number.
Introduction Aza heterocyclic hydrocarbons (AHHs) are sometimes known for their carcinogenic and mutagenic characteristics (1). As trace pollutants, AHHs are formed during incomplete combustion of nitrogen-containing substances and are therefore found in urban atmospheric particulate matter (21,tobacco smoke (3), and automotive exhaust (4, 5 ) . Coal tar (6),shale oil (7), and high-boiling petroleum distillates (8) also contain substantial amounts and various kinds of complexes. In early investigations, Sawicki and co-workers (2)have established the presence of AHHs in urban atmospheric particulate matter and identified a number of them, such as dibenz[a,j]acridine, dibenz[a,hlacridine, and some alkylbenzacridines. However, little information ( 4 , 5 , 9) on AHH emissions from many pollution sources has been amassed in comparison with other pollutants, especially carconogenic and/or mutagenic polycyclic aromatic hydrocarbons (PAHs). Separation methods for AHHs have been well reported. They have been separated by thin-layer chromatography (TLC) (IO),paper chromatography (111, paper electrophoresis (121, and conventional liquid chromatography *Author to whom correspondence should be addressed a t h i s present address: Department of Community Environmental Sciences, National Institute of Public Health, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108, Japan. 0013-936X/87/0921-1177$01.50/0
using adsorption (13) and ion-exchange packings (14). Gas chromatography has also been successfully applied with the flame ionization detector (15),with the nitrogen selective detector (16),or with mass spectrometry as a specific ion detector (17). High-performance liquid chromatography (HPLC) is generally recognized to be superior to TLC and conventional liquid chromatography (LC) in terms of efficiency and analytical precision. Nevertheless, few investigations on AHH analysis with actual environmental samples have been reported by means of the HPLC system. AHHs, with the exception of neutral carbazole and indole homologues, are found in the basic component of urban atmospheric particulate matter. This component only constitutes a small weight percentage (0.5-3%) of the organic matter (18). Consequently, there are some difficulties for direct analysis of AHHs in the organic extract. In our approach, we preseparate the AHH fraction by one-dimensional dual-band TLC and determine each peak by reversedphase HPLC followed by fluorescence spectrometry. Furthermore, this paper describes the distributions of A " s and major PAHs contained in an urban atmospheric particulate matter.
Experimental Section Environmental Sample. Urban atmospheric particulate matter was collected at a location 10 m from the side and 1.6 m above ground level of Sotobori St. beside the Science University of Tokyo in Shinjuku-ku, Tokyo, during April 1983. The collections were performed at 4-h intervals for the experiment by use of three high-volume air samplers (Kimoto Electric Co., Ltd.) with preweighed 8 X 10 in. quartz fiber filters (Gelman type-A). The airflow rates of each sampler were measured at 20-min intervals during one sampling period by a float-type flowmeter attached to the sampler. The average rate of sampling is 1.2-1.3 m3/min. The weight of a 24-h sample ranges from 150 to 240 mg. Filters were kept in a desiccator (relative humidity 50 %) until constant weight was reached before and after the samplings. After being weighed, the filters were wrapped with aluminum foil and stored in a refrigerator. Extraction. Organic soluble material was extracted from the six filters for 1day in a Soxhlet extractor for 10 h with spectrograde benzene-ethanol (4:l v/v by percent). The extract was dehydrated with anhydrous sodium sulfate (Na,SO,), filtrated, and concentrated to 20 mL in a rotary evaporator under reduced pressure below 35 "C.Two and eighteen milliliters of this extract were used for PAH and AHH analysis, respectively.
@ 1987 American Chemical Society
Environ. Sci. Technol., Vol. 21, No. 12, 1987
1177
Table I. HPLC System and Chromatographic Conditions
liquid chromatograph Hitachi 655 type, with Rheodyne 7125 sample injector, 20-pL loop guard column Unisil ODs, 0.4-cm i.d. X 1.0 cm, 5-pm particle size analytical column Zorbax ODs, 0.46-cm i.d. X 25 cm, 5-6-pm particle size; theoretical plates authorized, above 15000 mobile phase CH&N-HPO (7:3 v/v by percent) 50 column temp, OC detector Hitachi 650-40 fluorescence spectrophotometer, with 9-pL micro flow cell; photomultiplier gain, normal; see Table IV for excitation and emission wavelengths: band-Dass. 10 nm
Table 11. Ri Values and Recoveries of AHHs by the TLC System
recovery, 4-Af Ac Phe B(0Q B(h)Q B(a)Ac DB(aj)Ac lO-AB(a)P
Ri
%a
0.02 0.02
59.6 76.4 95.2 91.7 69.5 97.0 95.0 95.4
0.01 0.01
0.04 0.00 0.10
0.02
recovery, ~-MB(c)Ac 7,10-DMB(c)Ac 7,9-DMB(c)Ac DB(ac)Ac DB(ah)Ac 9-MDB(ac)Ac 7,11-DMB(c)Ac DB(ch)Ac
Ri 0.03 0.01
0.02 0.04 0.04 0.05 0.08 0.13
%"
88.4 85.4 96.1 94.8 97.8 96.6 83.4 80.0
aAverages of five determinations of 0.10 pg for each AHH.
~~
Liquid-Liquid Partition. Eighteen milliliters of the extract was reevaporated to near dryness, redissolved in 50 mL of ether (spectrograde diethyl ether), and partitioned by the method of Sawicki et al. (4). The CHC1, solution, which contains the basic component, was dehydrated, filtrated, concentrated, and redissolved in 2.0 mL of benzene-ethanol. The AHH fraction was preseparated from this solution by one-dimensional dual-band TLC described in the next section. Old ether contracted with air more or less contains peroxides that could be oxidized AHHs. For checking the stability of AHHs in ether solution, the quantitation of changes for some AHHs was determined by comparison of them in dimethyl sulfoxide (DMSO, reference) and in fresh (purified by usual way) and unfresh (sealed and lapsed 28 months after production) ether solutions. The concentration was ca. 3 X g/mL. Each determination was carefully performed by HPLC analysis immediately after the preparation of the solutions. Then, their solutions were stored in a refrigerator. They were once again analyzed after 24 h. The changes for B(a)Ac, DB(aj)Ac, DB(ac)Ac, DB(ah)Ac, and lO-AB(a)P (for definition of abbreviations, see Figure 1) were confirmed within *3 %. Preseparation. The AHH fraction was preseparated by the TLC plate (coated with Kieselguhr G and Florisil; Merck) with the developer (spectrograde n-pentanebenzene (19:l v/v by percent). The zone with the AHH fraction is marked under UV light at 254 nm and scraped from the plate into a small centrifuge tube. Extraction of AHHs was carried out ultrasonically with 2.0 mL of spectrograde DMSO for 15 min. The supernatant was submitted to A" analysis by means of HPLC after being centrifuged for 15 min at 3000 rpm. HPLC Analysis. The HPLC system and the chromatographic conditions adopted in this study are given in Table I. The mobile phase was prepared by mixing well CH,CN (HPLC-use grade) and deionized-distilled H 2 0 and by degassing under vacuum in an ultrasonic bath. The eluting solution was used under nitrogen atmosphere. The AHHs used in this study are shown in Figure 1. The individual AHH standard was prepared as 1.00 X lo4 (for (for HPLC TLC use) and as 1.00 X lo-' and 1.00 X use) g/mL solutions in benzene and DMSO. The mixtures of AHH standards were made up to the same concentrations from the individual solutions. The details of TLC/HPLC analysis for PAHs were documented previously (19). Results and Discussion Preseparation of AHHs by TLC. The organic materials from particulates emitted from many pollution sources have been extracted with benzene, ethylene chloride, cyclohexane, acetone, acetonitrile, and a benzeneethanol mixture (20). The extracts formed a dark brown 1178
Environ. Scl. Technol., Vol. 21, No. 12, 1987
Table 111. Ri Values of PAHs
abbreviation fluoranthene pyrene triphenylene chrysene benz[a]anthracene benzolilfluoranthene benzo[b]fluoranthene benzo[e]pyrene perylene benzo[a]pyrene dibenzo[a,c]anthracene dibenzo[a,h.]anthracene picene benzo[ghi]perylene dibenzo[a,i]pyrene coronene
Ft PY Tri Chry B(dA B(j)Ft B(b)Ft BWPy Per B(a)Py DB(ac)A DB(ah)A Pi B(ghi)Per DB(ai)Py CO
Ri 0.50 0.52 0.37 0.38 0.42 0.35 0.34 0.37 0.33 0.38 0.26 0.23 0.19 0.31
0.12 0.23
tar. Fluorescent PAHs, nitro-PAHs, and polycyclic quinones should be contained in the neutral component, fluorescent alcohol and carbonyl derivatives of PAHs in the acidic component, and fluorescent AHHs of quinoline and acridine derivatives in the basic component at relatively microquantity levels. A direct injection without further cleanup of the extracted solution in an HPLC column causes column deterioration and the overestimation against an actual value. The selective preseparation of objects from the extract is the indispensable part of HPLC analysis. As shown in Figure 2, all AHHs of interest can be found in a small region with Rjvalues between 0 and 0.15 (Table 11). Less polar compounds, i.e., aliphatic hydrocarbons, are found near the solvent front whereas nonpolar compounds such as PAHs with high R, values (Table 111) are detected above the region. The dark brown tar, which would be polymeric resins, is detected on the Kieselguhr layer. In addition, a pure AHH is concentrated as a sharp spot on the Florisil layer, and a pure PAH appears as an indistinct spot. Sawicki and co-workers (21)surveyed the separation behaviors of a few AHHs and PAHs by several TLC systems. They reported the same characteristics of the Florisil-TLC system against AHHs and PAHs. This means that Florisil, when nonpolar solvents such as npentane-benzene were used as the developer, strongly adsorbs polar compounds such as AHHs but weakly adsorbs nonpolar compounds such as PAHs. Consequently, polar solvents would give relatively good recovery yields for the extraction of AHHs from the scrap. Table I1 also shows the recoveries of the 16 AHHs when DMSO was adopted as the extracting solvent, and these values with the exception of a few AHHs are satisfactory. The developing time is rapid, within 15 min. Therefore, this preseparation of AHHs from the basic component with the TLC system is very useful as a cleanup procedure for
9 ) 7-Methylbenz(c)acridine
7-MB(c)Ac
1 ) 4-Azafluorene
4-Af
2 ) Acridine
Ac
1 0) 7,10-Dimethylbenz(c)actidine
7,lO-DMB(c)Ac
3 ) Phenanthridine
Phe
1 1 ) 7,9-Dimethylbenz(c)actidine
7,S-DMB(c)Ac
4 ) Benzo(f )quinoline
B(f)Q
1 2 ) Dibenz(ac)acridine
DB(ac)Ac
5 ) Benzo(h)quinoline
B(h)Q
1 3 ) Dibenz(ah)acridine
6 ) Benz(a1acridine
B(a)Ac
1 4 ) 9-Methyldibenz (ac)ac ridrne
9 -MDB(ac)Ac
7 ) Dibenz(aj)acridine
DB(aj)Ac
1 5 ) 7,11-Dirnethylbenz(c)acridine
7.11-DMBk)Ac
8 ) lO-Azabenzo(a)pyrene
lO-AB(a)P
1 6 ) Dibenz(ch1acridine
DB(ch )A c
@@
DB(ah)Ac
&@
* *4 *
@@
Figure 1. Identification, structures, and abbreviations of AHHs used in this study.
Table IV. Retention Times and Fluorometric Conditions for AHH Quantitation
0
2
O'
I.
b,
1 \-'
I
d
..t
-
I - \
I
.......
'-' e
i
/ - \
I
1
'-'
f
I
~
Figure 2. Preseparation of AHHs by onedimensional duai-band TLC (n-pentane-benzene, 19: 1 v/v by percent). (a) Fiorisii. (b) Kieselguhr 0. (c) Solvent front. (d) 16 AHH standards. (e) Basic component of the urban atmospheric particulate matter extract collected in Tokyo. (f) PAH standards: (1) pyrene, (2) benzo[a]pyrene, and (3) dibenzo[a ,i]pyrene. (g) AHH fraction.
HPLC analysis in view of selectivity, recoveries, rapidity, and column protection. HPLC Analysis. Table IV shows the retention times and fluorometric conditions for each AHH standard. The chromatograms for the mixture of the 16 AHH standards are shown in Figure 3. The chromatographic behavior of AHHs on a reversed-phase column is similar to that of the PAHs and is governed by the number of aromatic rings (19,22). Moreover, the behavior seems to depend on the steric availability of the aza nitrogen electron pairs, as suggested by other investigations (10,23).Under these chromatographic conditions (column, column temperature, and mobile phase), three groups of the AHHs are not resolved: (1) Phe, B(f)Q, and B(h)Q; (2) 7,9- and 7,lODMB(c)Ac; (3) 7,11-DMB(c)Acand DB(ch)Ac. But, two groups were resolved by the fluorometric techniques (se-
4-Af Ac Phe B(9Q BWQ B(a)Ac DB(aj)Ac 10-AB (a)P ~-MB(c)Ac 7,10-DMB(c)Ac 7,9-DMB(c)Ac DB (ac)Ac DB (ah)Ac 9-MDB(ac)Ac 7,1l-DMB(c)Ac DB(ch)Ac
retention time, min
excitation, nm; emission, nm
Mb
5.4 6.2 6.9 7.1 7.3 9.6 17.2 18.2 18.6 24.9 24.9 28.5 29.1 34.1 36.6 37.2
303; 322 246; 415 (249; 363)" (270; 364)" (264; 364)" 285; 395 285; 395 370; 440 285; 395 (285; 395)" (285; 395)" 278; 375 285; 395 285; 395 (285; 395)" (285; 395)"
167 179 179 179 179 229 279 253 243 257 257 279 279 293 257 279
Wavelengths for determination of retention times. Molecular weight. ~
lections of excitation and emission wavelengths) (Figure 3): (1) 7-MB(c)Ac and lO-AB(a)P; (2) DB(ah)Ac and DB(ac)Ac. The retention time precision within 1 day, Le., the coefficients of variation, is below 1.15%. Peak height value precisions within 1 day are also below 3.3%. The calibration curves in the peak height of HPLC/fluorescence response for the nine species of AHHs separated were found to be linear over a wide concentration ranging from 10 to lo00 pg, and the correlation coefficients for the AHHs are above 0.99. The detection limits (calculated as twice the signal to noise ratio) of the AHHs were about 10 pg under the chromatographic and fluorometric conditions. The actual quantitative analysis was carried out by the method of interpolation with the peak height values at the range of 20-200 pg. Figure 4 shows the chromatograms of the AHH fraction of the urban atmospheric particulate matter extract collected in Tokyo. The peaks corresponding to the standards were examined by stop-flow and scanning techniques and by the method of standard addition. As shown in Figure Environ. Sci. Technol., Vol. 21, No. 12, 1987
1179
Ex. 3 0 3 h m Em. 3 2 2 ,nm
___, 1
---P
1
Benz(a)acridine
Ex. 2 8 5 nm Em. 3 9 5 nrn
'
Dibenz(aj)acridine
Dibenz(ah)acridine
h c
VI
u C
+
c uu uC
>,
.-
x e -a
4-
v)
c
al
c
lL
.-c
I
al
Ex. 2 6 5 nmj Em. 4 1 5 nmi
V
t
Ex. 3 7 0 nm E m . 440 n m
al V
I Ex. 278 j Em. 3 7 5 :-
nm nm
(b)
v)
:
8
400
J
400
450
Wavelength
12
4 50
400
450 (nm)
Figure 5. Fluorescence emlssion spectra of three species of standards (-) and identlfled AHHs (- -) In AHH fraction of urban atmospheric particulate matter extract collected in Tokyo. These were measured by means of stop-flow and scanning techniques. For each excitation, see Table I V . Band-passes were 15 and 5 nm for excitation and emission, respectively.
LL
3
0
20
10
30
40
Table V. Average Concentrations of AHHs and PAHs in Urban Atmospheric Particulate Matter u d g of particulates
Time i n minutes Figure 3. Chromatograms of 16 AHH standards: (a) flrst and (b) second run. For peak identification, see Flgure 1.
Tokyo
US."
coal tar pitch pollutedb
AHHs Ex. 303 bm Em. 3 2 2 nm
. . . .
4-Af
Ex. 2 8 5 nm
Em. 395 nm
!
Ex. 2 4 6 n m / Em. 41 5 nmi
'
.
"
, / . . . , . . . . , . .
E x . 3 7 0 nm Em. 440 nm
i
j
Ex. 2 7 8 nm Ern. 3 7 5 nm
(b)
Ac B(a)Ac DB(aj)Ac DB(ac)Ac DB(ah)Ac IO-AB(a)P PAHs Ft PY Chry B(a1.4 Per B(e)Py B(a)Py DB(ah)A Pi B(ghi)Per DB(ai)Py co
3.2 X 3.5 3.3 4.3 X 2.9 X 3.6 X 3.2 X 3.7 X 6.3 X 4.3 x 2.0 X 7.8 3.0 X 2.6 X 6.6 2.5 X 4.7 X
IO-' 4.40
IO-'
X 10'
LOO x 103
2.0 3.0 X 10-'
6.0
6.0 X IO-'
5.0 x 10'
10-1
IO-'
-3.0 4.2
X 10' X 10' X
10' 10'
-3.0 5.5 4.2 4.6
10' 10'
6.3
10' 10' 10' 10'
1.1 X 10' 2.7 X 10'
X lo4 3.90 x 104
-4.30
10'
-3.30 X 10' 2.4 X IO2
X 10' X 10'
1.10 x IO' 1.80 X 10'
X 10'
2.70
1.5 X IO'
X
lo2
1.6 X 10'
From an average American urban atmosphere reported by Sawicki et al. (9). bParticulate matter from coal tar pitch polluted air reported by Sawicki et al. (2).
10
20
30
40
Time in m i n u t e s Figure 4. Chromatograms of AHH fraction of the urban atmospheric partlculate matter extract collected in Tokyo: (a) flrst and (b) second run. For peak ldentlflcation, see Flgure 1.
5, the fluorescence emission spectra of the three AHHs isolated are very similar to those of the standards, respectively. The spectra are not corrected for source intensity and detector wavelength response variations. Distribution of AHHs and PAHs. The urban atmospheric particulate matter collected in Tokyo is characterized as follows. The environment around the sampling location is a commercial and residential area. The stationary major emission sources of particulate matter 1180
Environ. Sci. Technol., Voi. 21, No. 12, 1987
regulated legally do not exist in the whole location, which is several kilometers across. We have previously reported (24)correlation between the number concentration of particles (of O.l-lO.O-~mdiameter) and traffic density at the same area. The correlation coefficient for the total number concentration (particles) per cubic meter) of the particles from automobile traffic (cars per hour) was given as 0.94 at a confidence level of 99%. Consequently, it is estimated that the automobile is the moving major emission source of the particulate matter. The traffic density on Sotobori St. beside the sampling location in a high traffic area was at a 36 000-37 000 cars/day level during a usual day. Table V shows the average concentrations of AHHs and PAHs during the sampling period. Simultaneously, the concentrations in the average American urban atmospheric particulate matter and in particulate matter from coal tar pitch polluted air, as reported by Sawicki et al. (9, 2), are
cited in the table. As is evident from the table, the concentrations of the 11 species quantitated in both atmospheric particulate matters were adventitiously at the same levels, and B(a)Ac in relatively high concentration was found among the three AHHs. In addition, it was found that the concentrations of the AHHs were about 10-1000 times lower than those of the major PAHs. Dong et al. (25) have reported much higher concentrations of two-ring AHHs and progressively smaller amounts of higher ring compounds in New York samples. The reverse observation was reported for Antwerp samples studied by Cautreels and Van Cauwenberghe (17). They found relatively higher concentrations of four- and five-ring AHHs compared to the two-ring compounds. In our samples, the concentrations of Ac to lO-AB(a)P indicate the former tendency. On the other hand, three data were in agreement with the tendency of PAH concentrations. Dong et al. have estimated that the fact that European cities generally burn more coal might explain this important difference. However, the tendency of AHH and PAH concentrations in particulate matter from coal tar pitch polluted air is the same as those in Tokyo, New York, and the US. Therefore, it is estimated that there are other effects on AHH emissions.
Conclusions In the present situation, little is known about the distributions of AHHs from many emission sources and the long-term biological effects of A " s . This analytical study reveals valuable data on the basic component, in terms of AHH preseparation by TLC and new compounds identified and their relative concentrations. Our approach would also be adaptable to other environmental sample types such as tobacco smoke, coal tar, shale oil, and high-boiling petroleum products where AHHs are presept in relative higher concentrations. More investigations are obviously needed before we have a better understanding of the formations, sources, and effects of AHHs. This knowledge is very important for the diminution of increasing AHHs to the atmosphere in the near future with use of liquid fuels obtained by gasification of nitrogen-rich shale oil and coal. Acknowledgments We express our appreciation to H. Matsushita, Department of Community Environmental Science, National Institute of Public Health, for his valuable discussions and encouragement and H. Ikeda for his assistance in part of this study. Registry No. 4-M)244-99-5;Ac, 260-94-6; Phe, 229-87-8; B(f)Q, 85-02-9; B(h)Q, 230-27-3; B(a)Ac, 225-11-6; DB(aj)Ac, 224-42-0; 10-AB(a)P, 189-92-4; 7-MB(c)Ac, 3340-94-1; 7,10-DMB(c)Ac, 2381-40-0; 7,9-DMB(c)Ac, 963-89-3; DB(ac)Ac, 215-62-3; DB-
(ah)Ac, 226-36-8; g-MDB(ac)Ac, 110270-98-9; 7,11-DMB(c)Ac, 32740-01-5; DB(ch)Ac, 224-53-3; Ft, 206-44-0; Py, 129-00-0; Chry, 218-01-9; B(a)A, 56-55-3; B(e)Py, 192-97-2;Per, 198-55-0; B(a)Py, 50-32-8; DB(ah)A, 53-70-3; Pi, 213-46-7; B(ghi)Per, 191-24-2; DB(ai)Py, 189-55-9; Co, 191-07-1.
Literature Cited (1) Acros, J. C.; Argus, M. F. Adv. Cancer Res. 1968, 11, 305-471. (2) Sawicki, E.; McPherson, S. P.; Stanley, T. W.; Meeker, J.; Elbert, C. Air Water Pollut. 1965, 9, 515-524. (3) Van Duuren, B. L.; Bilbao, J. A.; Joseph, C. A. J. Natl. Cancer Inst. (U.S.) 1960,25, 53-61. (4) Sawicki, E.; Meeker, J. E.; Morgan, M. Arch. Environ. Health 1965, 11, 773-775. (5) Handa, T.; Yamauchi, T.; Sawai, K.; Yamamura, T.; Koseki, Y.; Ishii, T. Environ. Sci. Technol. 1984, 18, 895-902. (6) Lang, K. F.; Eigen, I. Fortschr. Chem. Fortsch. 1967, 8, 91-170. (7) Uden, P. C.; Siggia, S. Abstracts of Papers, Centennial American Chemical Society Meeting, New York, April 7, 1976; American Chemical Society: Washington, DC, 1976; ANAL 57. (8) McKay, J. F.; Weber, J. H.; Latham, D. R. Anal. Chem. 1976,48, 891-898. (9) Sawicki, E.; Meeker, J. E.; Morgan, M. J. Air Water Pollut. 1965, 9, 291-298. (10) Engel, C. R.; Sawicki, E. J. Chromatogr. 1967,31, 109-119. (11) Sawicki, E.; Praff, J. P. Anal. Chim. Acta 1965,32,521-534. (12) Sawicki, E.; Guyer, M.; Engel, C. R. J. Chromatogr. 1976, 30, 522-527. (13) Sawicki, E.; Stanley, T. W.; Elbert, W. C. J. Chromatogr. 1965,13,512-519. (14) Snyder, L. R. Anal. Chem. 1969,41, 314-323. (15) Alberini, G.; Cantuti, V.; Cartoni, G. P. in Gas Chromatography;Littlewood, A. B., Ed.; The Institute of Petroleum: London, 1967; pp 258-271. (16) Lee, M. L.; Bartle, K. D.; Novotny, M. V. Anal. Chem. 1975, 47, 540-541. (17) Cautreels, W.; Van Cauwenberghe,K. Atmos. Environ. 1976, 10,447-457. (18) Hoffmann, D.; Wynder, E. L. in Air Pollution, 3rd ed.; Stern, A. C., Ed.; Academic: New York, 1977; Vol. 11, Chapter 2. (19) Handa, T.; Yamauchi, T.; Ikeda, H. Fire Sci. Technol. (Tokyo) 1984,4, 111-119. (20) Salamone, M. F.; Heddel, J. A.; Katz, M. Enuiron. Int. 1979, 2, 37-43. (21) Sawicki, E.; Stanley, T. W.; Praff, J. D.; Elbert, W. C. Anal. Chim. Acta 1964, 31, 359-375. (22) Dong, M.; Locke, D. C.; Ferrand, E. Anal. Chem. 1976,48, 368-372. (23) Vivilecchia, R.; Thiebaud, M.; Frei, R. W. J. Chromatogr. Sci. 1972, 10, 411-416. (24) Handa, T.; Kato, Y.; Yamamura, T.; Ishii, T.; Suda, K. Environ. Sci. Technol. 1980, 14, 416-422. (25) Dong, M. W.; Locke, D. C.; Hoffmann, D. Environ. Sci. Technol. 1977, 11, 612-618.
Received for review July 31,1985. Revised manuscript received May 15, 1987. Accepted July 23, 1987.
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