970
Anal. Chem. 1987,59,970-973
carboxyl groups in the silica gel matrix [8]because of the similarity of the R T P emission wavelengths. This result is in contrast to the RTF results for BMQ and BwQH+ which shifted to longer wavelengths as the amount of analyte increased (Table I). The B[flQH+ R T P excitation spectra, while exhibiting changes with the amount of B[LlQH+,were found to be almost independent of emission wavelength monitored for a given amount (Figure 6a,b). The excitation spectra for the 20-pg sample were not as smooth as the 100-ng sample and the relative intensities of the bands at 280 and 366 nm showed different relative magnitudes for the 100-ng and 20-pg samples. Thus, the phosphorescent B[flQH+ molecules at a given amount were experiencing similar ground-state interactions and environments but not necessarily the same environments. The BMQH+ R T P emission spectra were found to be essentially independent of the wavelength of the exciting radiation a t all amounts (Figure 6a,b). The R T P emission spectra in Figure 6b for the 2 0 - ~ gsample did show greater relative intensities changes with excitation wavelength compared to that of the 100-ng sample. This is probably due to the weak RTP signals at 20 pg of B[flQH+. Because of the similarity of the maximum emission wavelengths, one can conclude that the B[flQHf molecules were interacting with carboxyl groups. This is supported by the results in Table I, which show that the R T P emission wavelengths were independent of the amount of B[flQH+, except for one wavelength. Registry No. Benzo[flquinoline, 85-02-9.
LITERATURE CITED Parker, R. T.; Freedlander, R. S.;Dunlap. R. B. Anal. Chim. Acta 1980, 779, 189. Parker, R. T.; Freedlander, R. S.;Dunlap, R. B. Anal. Chim. Acta 1980, 720, 1. Vo-Dlnh, T. Room Temperature Phosphorimetry for Chemical Analy sis; Wiley: New York, 1984.
Hurtubise, R. J. Solid Surface Luminescence Analysis ; Marcel Dekker: New York, 1981. Schulman, E. M.; Parker, R. T. J . Phys. Chem. 1977, 8 7 , 1932. Ford, C . D.; Hurtubise, R. J. Anal. Chem. 1978, 5 0 , 610. Ford, C . D.; Hurtubise, R. J. Anal. Chem. 1979, 51, 659. Ford, C.D.; Hurtubise, R. J. Anal. Chem. 1980, 5 2 , 656. Von Wandruszka, R. M. A.; Hurtubise, R. J. Anal. Chem. 1977, 49, 2764. Hurtubise, R. J. Talanta 1981, 28, 145. Ramasamy, S. M.; Hurtubise, R. J. Anal. Chem. 1982, 5 4 , 1642. Ramasamy, S.M.; Hurtubise, R. J. Anal. Chem. 1982, 54, 2477. Ramasamy, S . M.; Hurtubise, R. J. Anal. Chim. Acta 1983, 752, 83. Senthilnathan, V. P.; Ramasamy, S. M.; Hurtubise, R. J. Anal. Chim. Acta 1984, 757, 203. Goldman, J. J. Chromatogr. 1973, 78, 7. Kortum. G. Reflectance Spectroscopy; Springer-Verlag: New York, 1969. Hurtubise, R. J. Anal. Chem. 1977, 49, 2160. Prosek, M.; Kucan, E.; Katic, M.; Bano, M.; Medja, A. Chromatographia I978, 1 1 , 578. Zweidinger, R.; Winefordner, J. D. Anal. Chem. 1970, 4 2 , 639. Kiseiev, A. V.; Lygin, V. I. Infrared Spectra of Surface Compounds; Wiley: New York, 1975. Robin, M.; Trueblood, K. N. J . Am. Chem. SOC. 1957, 79, 5138. Leermakers, P. A.; Nicholls, C. H. Advances in Photochemistry;WileyInterscience: New York, 1971. Nakamizo, M. Specfrochlm. Acta 1966, 2 2 , 2039. Masetti, F.; Mazzucato, U.; Birks, J. B. Chem. Phys. 1975, 9 , 301. Favaro, G.;Masetti, F.; Mazzucato, U. Spectrochim. Acta, Part A 1971, 27A, 915. Mataga, N.; Kaifu, Y.; Koizumi, M. Bull. Chem. SOC.Jpn. 1956, 2 9 , 33. Lloyd, J. B. F. Anahst (London) 1975, 700, 529. Thin Layer Chromatography; Stahl, E. Ed.; Springer-Verlag: New York, 1969; p 13. Niday, G. L.; Seybold, P. G. Anal. Chem. 1978, 5 0 , 1577. Bauer, R. K.; de Mayo, P.; Natarajan, L. V.; Ware, W. R. Can. J , Chem. 1984, 62, 1279. Bauer, R. K.; de Mayo, P.; Ware, W. R.; Wu, K. C. J . Phys. Chem. 1982, 86, 3781.
RECEIVED for review April 28, 1986. Resubmitted November 17, 1986. Accepted December 1,1986. Financial support for this project was provided by the Department of Energy, Division of Basic Energy Sciences, Contract No. DE-ACO280ER10624 and DE-FG02-86ER13547.
Direct Determination of Polycyclic Aromatic Hydrocarbons in Extracts of Particulate Matter A. E. Elsaid, A. P. D’Silva,* V. A. Fassel, and R. L. M. Dobson Ames Laboratory-USDOE
and Department of Chemistry, Iowa State University, Ames, Iowa 50011
Laser-exclted Shpd’skll spectrometry has been d z e d for the dlrect determlnatlon of polycycllc aromatic hydrocarbons (PAH) in high-temperature extracts of partlculate matter. Ouantltative data on seven PAH present in two National Bureau of Standards standard reference materials (SRM 1649 and 1650) are reported.
The combustion of fossil fuels and biomass, be it in utility power plants, trucks, and automobiles or in home fireplaces, usually introduces finely divided particulate matter into the environment. The large surface area of these particles results in the preferential adsorption and deposition of highly carcinogenic or mutagenic polynuclear organic materials (POM) that are usually present in the particulate laden effluent streams. One class of compounds of particular interest is the polynuclear aromatic hydrocarbons (PAH). Because this class 0003-2700/87/0359-0970$0 1.50/0
of compounds contains many mutagenic and carcinogenic compounds, there is serious concern about the potential environmental impact resulting from the widespread dispersal of this particulate matter. This concern is intensified by the realization that adsorption of the PAH on the surface of the particulate matter may enhance carcinogenic and mutagenic potency (1). As a consequence of these considerations, extensive studies designed to obtain PAH profiles of urban air particulate matter have been performed (2). Generally, the profile data were obtained via the extraction of the PAH into appropriate low boiling solvents (3-5), followed by chromatographic isolation of the compounds of interest. Quantitation has usually been performed via mass spectroscopic or ambient-temperature, luminescence approaches. In a recent communication, we enumerated the deficiencies inherent in these approaches, and recommended an overall procedure that satisfies the key criteria desired in an analytical method for this purpose (6). This procedure was based on 0 1987 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 59, NO. 7, APRIL 1, 1987
971
.06
4.
ex
-
387.56 m
407.40
425.69
38 1
407
391
WAVELENGTH
017
427
(NM)
Figure 2. Excitation (A) and fluorescence (B) spectra of B[k]F.
405
WAVELLNGTH
415
425
(NM)
Flgure 1. Excitation (A, A') and fluorescence(B, B') spectra of B[a]P (bottom) and B [ a ] P - d , , (top).
the rapid extraction of small samples (50-150 mg) into high boiling point (>250 " C ) solvents that are compatible with the subsequent direct determination of the individual compounds by laser-excited Shpol'skii spectrometry [LESS] (7,8). No preseparation of the individual compounds was required by this procedure. In this communication we discuss the further application of this approach to the quantitative determination of seven marker PAH compounds in the No. 1650 National Bureau of Standards (NBS) diesel particulate standard reference material (SRM). Data are also included for four additional marker compounds in the NBS-SRM No. 1649 urban air particulate. Site-Specific, Laser-Excited Shpol'skii Spectra. In the past various investigators have described the ultraviolet-excited luminescence spectra of the compounds considered in the present investigation and an atlas of these spectra has been published (9). These spectra, however, have limited utility for the direct determination of individual PAH in complex mixtures. The degree of selectivity and specificity required for this purpose has been achieved via the utilization of tunable, dye-laser-excited, site-specific Shpol'skii spectrometry (8, 10).
EXPERIMENTAL SECTION The two SRMs were obtained directly from the National Bureau of Standards, Washington, DC. The PAH compounds (benzo[a]pyrene (B[a]P),benzo[klfluoranthene (B[k]F), benzo[ghilperylene (B[ghi]P), benz[a]anthracene (B[a]A), and benzo[e]pyrene (B[e]P))were obtained from the Community Bureau of Reference (BCR), Commission of the European Communities, Brussels. The pyrene and perylene were obtained from Analabs, Inc., North Haven, CT. The source for the deuterated compounds B[a]P-dlz, B[a]A-dlz,pyrene-d,,, and perylene-dlz was Merck &
WAVELENGTH
(Nfi)
Figure 3. Excitation (A) and fluorescence (B) spectra of benzo[ghi]perylene.
Co., Inc./Isotopes, St. Louis, MO. The procedure for the high-temperature extraction and the instrumentation utilized for the observation of LESS in the extracts has been described (6,8). The salient features of the high-temperature technique are as follows: (1)small-sized samples of 100 mg or less; (2) small solvent volumes (1to 2 mL); (3) short extraction time of less than 5 min; (4) high extraction efficiency for a wide range of compounds; and (5) an extraction solvent (diphenylmethane), which is compatible with n-octane, the Shpol'skii solvent. For this investigationthe extracts were diluted at a 1:200 ratio by n-octane solvent.
RESULTS AND DISCUSSION Spectra of PAH. A key requirement for the successful direct determination of individual PAH in complex mixtures of organic compounds is the availability of sharp-line excitation and luminescence spectra. This condition can be fulfilled for many compounds via the utilization of the Shpol'skii effect (7). Typical site-specific, fluorescence excitation-emission spectra for the various compounds, reported here for the first time, are shown in Figures 1-7. To the best of our knowledge, except for pyrene-dlo in n-hexane ( I I ) , the combined excitation-emission spectra of other deuterated compounds referred to in this paper have not been reported before. Excitation and fluorescence spectra shown in Figures 1 to 7 were obtained with 1 ppm solutions. Considering the fluorescence excitation and emission spectra first, it should be noted that compounds studied in the present investigation populated only one or two prominent sites in n-octane. The spectra shown in Figures 1 to 7 therefore represent selective excitation of the respective molecules in
ANALYTICAL CHEMISTRY, VOL. 59, NO. 7, APRIL 1 , 1987
972
Table I. Line Selection and Method of Quantitation Utilized To Obtain Analytical Data compound name
nm
A,,
388.72 386.78 387.79 374.18 357.31 366.58 420.52
B[aIP WkIF B [ghi]P WaIA pyrene B[eIP perylene a
internal reference"
nm
A,,
method used for quantitation
402.98 403.55 419.56 384.16 372.01 537.59 444.57
name
int ref int ref int ref int ref int ref std add std add with int ref
k,,
nm
B[alP-d,z B[aIP-diz B[alP-d,, B [ a1A-diz pyrene-d,,
402.06 402.06 402.06 383.66 370.93
perylene-d,,
443.52
for the internal reference was the same as that of the target compound.
A,,
E' A'
I
F
VAIELnL-I
,"ll)
Flgure 6. Excitation (A), fluorescence (E), and phosphorescence (C) spectra of
B[e]P. The phosphorescence spectrum was observed for
a 1 ppm solution. ,
,
b
'il
L
i
L
!
111
386
406
396
A'
I h4
~AVELEMGTP ( N U )
Flgure 4. Exckation (A, A') and fluorescence (E, B'), spectra of (bottom) and B[a]A-d,, (top).
lm
B'
hem = 450.30 nm
h ex = 418.03 nm
B[a]A
= 363 61
MI
3'
5
>
t m z c z
A
Y
w
I
d
2
2=
= 361.11 m
c
354
362
370
WAVELENETH
375
385
I
CII
395
!LIM)
Flgure 5. Excitation (A, A') and fluorescence (E, B'), spectra of pyrene (bottom) and pyrene-d,, (top).
only one selected type of crystallographic site. There are instances where the indicated laser excitation wavelengths may be different from those reported by us earlier (10,12) for molecules occupying a different type of site. A few detailed notes on these spectra are appropriate. Nonselective excitation of the fluorescence of B[a]A at 339 nm revealed the presence of two prominent lines at 384.16 nm and 384.35 nm arising from two sites. In spite of their
WAVELENGTH (nm)
Flgure 7. Excitation (A, A') and fluorescence (E, E') spectra of perylene (bottom) and perylene-d
,*(top).
close proximity, the individual lines could be selectively excited without interference from the other. In Figure 4 the fluorescence line at 384.16 nm and the associated excitation spectrum are shown. The presence of the two sites in the spectrum of B[a]A-dI2 can be noted in Figure 4B' by the unresolved peak on the high wavelength side of the 383.46-nm
ANALYTICAL CHEMISTRY, VOL. 59, NO. 7, APRIL 1, 1987 e 973 Table 11. Comparison of Analytical Data urban air particulate
diesel particulate (SRM 1650) compound LESS, ppma NBS, ppm LESS, ppmn NBS, ppm (SRM 1649)
B[a]P B[k]F B[ghi]P B[a]A
pyrene B[e]P perylene a
3.2 f 0.2 2.5 f 0.3 6.3 f 0.4 2.8 f 0.2 6.6 f 0.3 3.2 f 0.2 0.73 f 0.04
2.9 f 0.3 2.0 f 0.2 4.7 f 0.2 2.5 f 0.3 6.3 f 0.4 3.3 f 0.2
1.7 f 0.2 0.5 f 0.1 2.4 f 0.2 5.8 f 0.3 50.7 f 1.5 9.7 i 0.3 0.15 f 0.01
1.9 f 1.7 2.0 f 0.4 3.9 f 2.4 7.7 f 3.8 42.9 f 6.9 9.3 f 2.7 0.13 f 0.01
Deviation from the mean of triplicate values.
line. In the fluorescence spectrum of perylene (Figure 7), there are two prominent lines at 444.57 nm and 451.64 nm. At concentrations above -0.5 ppm, the 0-0 line a t 444.57 nm is subject to severe self-absorption arising from inner filter effects. The self-absorption is evident in the fluorescence spectrum of perylene-dlz in Figure 7B'. This spectrum was obtained at a concentration of 1.0 ppm, at which concentration the self-absorption of the 443.52-nm line causes an inversion of the 443.52 nml450.3 nm intensity ratio. Thus, for the determination of perylene, the intensity ratio of the line pair 444.57 nml451.64 nm should be measured. A ratio of less than 2.0 indicates self-absorption and measurements should be made after further sample dilution. In the phosphorescence spectrum for B[e]P shown in Figure 6, the site-selective line at 537.59 nm, excited by laser radiation a t 366.58 nm, was sufficiently intense to be used for the quantitative determinations presented in this paper. Quantitative Data on SRMs. For quantitative determinations of B[a]P, B[a]A, pyrene, and perylene, deuterated analogues of the above compounds were utilized as the externally added internal reference compounds. For B[a]P, B[k]F, and B[ghi]P, the internal reference was the 402.06-nm line of B[a]P-d,,. This approach was feasible because of the partial overlap in the excitation spectra of B[a]P-dlz and the three analytes. Thus, the spectra of B[a]P-dlz and B[a]P, B[k]F, and B[ghi]P analyte could be simultaneously observed by exciting a t appropriate wavelengths. An example of this approach is shown in Figure 2, ref 6. For B[e]P, no deuterated analogue or a useful overlapping internal reference line was readily available. The method of standard addition was therefore used for the determination of this compound. Because of the low concentration of perylene in the sample, the
method of standard addition was combined with the internal reference approach for the positive identification and quantitation of the compound. The analytical wavelengths and the methods of quantitation are indicated in Table I. For the determination of PAH at the 1 to 10 ppm level in mixtures as complex as those represented by the urban air and diesel exhaust particulate samples, agreement within f20-30% of the amount present as determined by independent analytical methods is considered acceptable. A comparison of the quantitative data obtained for the seven compounds in the two reference samples shown in Table I1 reveals that only the results for B[k]F in SRM 1650 do not conform to this criterion. Repeated LESS analysis of different portions of this sample produced analytical results for B[k]F consistent with those shown in Table 11. Registry No. B[a]P, 50-32-8;B[k]F, 207-08-9; B[ghi]P, 19124-2; B[a]A, 56-55-3;B[p]P, 192-97-2; pyrene, 129-00-0; perylene, 198-55-0.
LITERATURE CITED (1) Committee on Biologic Effects of Atmospheric Pollutants Particulate Polycyclic Organic Matter; National Academy of Sciences: Washington, DC, 1972. (2) Grimmer, G. I n Handbook of Polycyclic Aromatic Hydrocarbons; Bjorseth, A., Ed.; Marcel Dekker: New York, 1983; Chapter 4. (3) Griest, W. H.; Caton, J. E. I n Handbook of Polycyclic Aromatic Hydrocarbons; Bjorseth, A., Ed.; Marcel Dekker: New York, 1983; Chapter 3. (4) Wise, S.A.; Bowie, S. L.; Chesler, S. N.; Cuthrill, W. F.; May, W. E.; Rebbert, R. E. Proceedings of the 6th International Symposium on Polynuclear Aromatic Hydrocarbons; Cooke, M., Dennis, A. J., Fisher, G. L., Eds.; Battelle Press: Columbus, OH, 1982; p 919. ( 5 ) Bjorseth, A. Anal. Chim. Acta 1977, 9 4 , 21-27. (8) Renkes, G. D.; Walters, S. N.; Woo, C. S.; Iles, M. K.; D'Silva, A. P.; Fassel, V. A. Anal. Chem. 1983, 5 5 , 2229-2231. (7) Shpol'skii, E. V. Sov. Phys.-Usp. (Engi. Trans/.)1980, 3 , 372-389. (8) D'Silva, A. P.; Fassel, V. A. Anal. Chem. 1984, 5 6 , 985A-1000A. (9) Colmsjo, A. L.; Ostman, C. E. Atlas of Shpoi'skii Spectra and Other Low Temperature Nuorescence Spectra of POM; University of Stockholm: Stockholm, Sweden, 1981. (10) Yang, Y.; D'Silva, A. P.; Fassel, V. A. Anal. Chem. 1981, 5 3 , 894-899. (11) Cunningham, K.; Siebrand, W.; Williams, D. F.; Orlandi, G. Chem. Phys. Lett. 1973, 2 0 , 496-500. (12) Yang, Y.; D'Silva, A. P.; Fassel, V. A. Anal. Chem. 1981, 5 3 , 2107-2109.
RECEIVED for review September 2,1986. Accepted December 1, 1986. The Ames Laboratory is operated by Iowa State University for the US. Department of Energy under Contract No. W-7405-ENG-82. This research was supported by the US. DOE Office of Health and Environmental Research, Physical and Technological Studies.
