United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S4-84-033 May 1984
SEPA Project Summary
Analysis of Polynuclear Aromatic
Hydrocarbons in Paniculate
Matter by Luminescence
Techniques
W. A. Ivancic, L L Brown, R. M. Riggin, and R. H. Barnes
Fluorescence, phosphorescence, and
heavy-metal activated room tempera-
ture phosphorescence spectra were
obtained for ten polycyclic aromatic
hydrocarbon (PAH) reference
compounds individually and in mixtures
on quartz plates and paniculate matter.
The results indicate that multicompo-
nent analysis of PAHs on airborne par-
ticulate matter may be possible with the
development of appropriate multicom-
ponent spectral deconvolution proce-
dures. The direct analysis approach in
combination with the use of solvent
extraction followed by fluorescence
analysis can provide a rapid means of
analysis for PAHs both within and on
the surface of paniculate matter. Direct
phosphorescence was too weak to be
useful at 5-10 //g/g levels found in
many types of paniculate samples.
Heavy-metal activated room-tempera-
ture phosphorescence appears more
sensitive to matrix and substrate effects
and less amenable to multicomponent
analysis than fluorescence.
The fluorescence spectrum of benzo-
(a)pyrene was found to be affected by
exposure to low levels of ozone.
However, the fluorescence spectrum
retains characteristic features that
enable identification of the
benzo(a)pyrene.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
This project involved an exploratory
study to evaluate the potential of optical
fluorescence and phosphorescence tech-
niques for the direct analysis of polycyclic
aromatic hydrocarbons (PAHs) in urban
paniculate samples. Current chemical
procedures for the analysis of PAHs in
paniculate samples are both time
consuming and expensive. If the lumines-
cence techniques without involved
chemical extractions were available for
PAH paniculate analysis, it would greatly
extend the capabilities for the study and
survey of carcinogen-bearing paniculate
materials in the environment.
The facts that PAHs tend to be highly
luminescent with characteristic spectra
for individual compounds suggest the
possible use of fluorescence and
phosphorescence for paniculate analysis.
These techniques simply involve irradiat-
ing a sample with ultraviolet light and
analyzing the timing and intensities of the
spectral components of the lumines-
cence. Fluorescence emissions for PAHs
generally decay with emission lifetimes
less than 10/L/s while phosphorescence is
characterized by lifetimes extending from
about 100//s to minutes. Through selec-
tive wavelength excitation coupled with
temporal and spectral analysis of the
emitted luminescence, it is often possible
to apply multicomponent analysis
procedures to identify and quantify
individual species in complex mixtures.
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As a basis for these studies, ten major
PAHs typically found in urban
particulates were selected as reference
compounds. The selected compounds are
listed in Table 1. These compounds were
used individually and in mixtures of
various complexities on quartz substrates
and on paniculate samples to generate
luminescence data for evaluating the
utility of the fluorescence and heavy-
metal-activated room-temperature phos-
phorescence (RTF) techniques for the
direct analysis of PAHs on paniculate
materials.
Also investigated as part of this study
were the effects of low-level ozone
exposure on fluorescence from
benzo(a)pyrene and the use of super-
critical fluid C02 to extract PAHs from
particles for fluorescence analysis.
Procedure
A Molectron® frequency doubled
Model DL14 pulsed dye laser pumped by
a nitrogen laser was employed as the
excitation source for the luminescence
measurements. Samples of the reference
compounds were deposited in solvents
onto S1-UV quartz plates or particle
samples and then evaporated to dryness.
The beam from the dye laser was focused
onto the surface of the samples at an
angle 70° from the normal and the
luminescence collected with f/4 optics in
a direction normal to the sample and
spectrally analyzed using a f/9 1.26-m
spectrometer with a low-noise
photomultiplier tube. The signal from the
photomultiplier was processed with a
dual photon counting system to allow
both fluorescence and phosphorescence
spectra to be recorded simultaneously.
The photon counting system was
synchronized to the laser pulse and the
dual detection channels gated with
separate delays and variable time
windows. Output from the dye laser was
monitored and used to normalize the
luminescence to compensate for
variations in the output of the dye laser.
Results and Discussion
Typical fluorescence spectra are shown
in Figures 1 and 2 for benz(a)anthracene
on quartz and on paniculate standard
reference material NBS SRM 1633. For
the quartz sample, 4 fiL of 100 ppm
acetone solution was deposited as a 2
mm diameter spot, while for the panic-
ulate sample, 50/yL of 100 ppm solution
was deposited on 5.8 mg of NBS SRM
1633. In the case of all the reference
PAHs, the type of substrate influenced
the spectra; however, the individual
Table 1. Polycyclic Aromatic Hydrocarbons Used as Reference Compounds
Polycyc/ic Aromatic Compounds
Formula
Structure
Benzo(b)fluoranthene
(3.4-Benzofluoranthene)
Benzo(k)f/uoranthene
(11,12-Benzofluoranthenej
Benzo(a)pyrene
(3.4-Benzopyrene)
Benzo(e)pyrene
(4,5-Benzopyrene)
Benz/a)anthracene
(1.2-Benzanthracene)
Chrysene
(1,2-Benzophenanthrene)
Benzo(ghi)perylene
(1.12-Benzoperylene)
1.2.3.4-Dibenzanthracene
1.2,5.6-Dibenzanthracene
(Dibenzfa.hjanthracene)
F/uoranthene
(1.2-Benzacenaphthene)
C2(//12
C \sH\2
C22W|2
300
Figure 1.
400 500
Wavelength (NM.)
600
Fluorescence reference spec-
trum excited at 292 nm for
benzfa) anthracene on quartz.
.c
01
o
c
300 400 500 500
Wavelength (NM.)
Figure 2. Fluorescence spectrum excited
at 295 nm for chrysene on NBS
SRM 1633.
compounds still retained their character-
istic features.
Fluorescence spectra for an equal
mixture of all ten reference compounds
on quartz and NBS SRM 1633 are
presented in Figures 3 and 4. The quartz
sample was deposited as 10/i/L of a 100
ppm solution made up of 10 ppm of each
reference PAH. For the paniculate
sample, 50pLof the mixture solution was
deposited on 5.5 mg of NBS SRM 1633.
Detection limits for the PAHs on the
paniculate were about 2.5 ng. Cursory
examination of the mixture spectra
indicated that it should be possible to
analyze for the individual PAHs in the ten-
component mixtures using multicompo-
nent analysis procedures.
Experiments using a J&W Scientific
(Orangevale, CA) high-pressure
supercritical C02 Soxhlet extractor
showed that organic constituents in
paniculate materials could easily be
extracted and transferred to quartz plates
for fluorescence analysis.
For the heavy-metal activated RTP
studies the time windows were set to
separate the long-lived phosphorescence
from fluorescence. PAHs on quartz, NBS
SRM 1633 and filter paper were activated
with lead acetate. The phosphorescence
measured was found to be extremely
sensitive to the type of substrate and
degree of drying of the sample, making it
difficult to obtain reproducible results.
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300 400 500 600
Wavelength (NM.)
Figure 3. Fluorescence spectrum excited
at 292 nm for equal part mixture
of all 10 PAH reference com-
pounds on quartz.
W. A. Ivancic, L L Brown, R. M. Riggin, and R. H. Barnes are with Battelle's
Columbus Laboratories, Columbus, OH 43201.
Nancy K. Wilson is the EPA Project Officer (see below).
The complete report, entitled "Analysis of Polynuclear Aromatic Hydrocarbons in
Paniculate Matter by Luminescence Techniques," (Order No. PB84-181 882;
Cost: $1O.OO, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, v'A 221'61
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
U.S. GOVERNMENT PRINTING OFFICE: 1984 — 759-015/7712
300
Figure 4.
400 500
Wavelength (NM.)
600
Fluorescence spectrum excited
at 292 nm for equal part mixture
of 10 PAH reference compounds
onNBSSRM1633.
Also, the intensity of the heavy-metal-
activated RTP was weaker than direct
fluorescence with a detection limit of
about 1 60 ng.
The ozone studies were conducted by
exposing benzo(a)pyrene deposited on a
quartz plate to 1 ppmv of ozone for various
periods of time, after which fluorescence
measurements were made and compared
with a control sample that had not been
exposed to ozone. Changes in the
fluorescence spectrum for benzo(a)pyrene
were produced by the ozone exposure;
however, the characteristic spectral
features were still retained after a 42-
hour exposure.
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