EPA-R2-72-004
October 1972
Environmental Protection Technology Series
Identification of Polychlorinated
Biphenyls in the Presence of
DDT-Type Compounds
33
\
UJ
CD
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards..
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EPA-R2-72-C/A
October 1972
IDENTIFICATION OF POLYCHLORIWATED
BIPHENYLS IN THE PRESENCE OF DOT-TYPE
COMPOUNDS
Contract No. 68-01-0082
Project 16020 GIY
Project Officer
Dwlght G. Bellinger
Analytical Quality Control Lab.
NERC - EPA
Cincinnati, Ohio ^5268
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20k6Q
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington. D.C. 20402 - Price »1.W
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EPA Reviev; notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or
coirc.ercial products constitute endorsement or recommenda-
tion for use.
11
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ABSTRACT
Polychlorinated biphenyls (PCB's) interfere with gas chromatographic
analyses of DDT and related compounds, necessitating a simple inde-
pendent method for PCB determination. The purpose of the present
study was to determine the applicability of low temperature (77° K)
luminescence methods to this problem. Basic studies included docu-
mentation of excitation/emission spectra of 6 pesticides (p, p'- and
o,p'-DDE, DDD, and DDT), 7 PCB isomers, and 5 PCB mixtures
(Aroclors). Although phosphorescence spectra of the DDD and DDT
compounds are very similar, possible differences in lifetime and
polarization measurements may aid in differentiation. Emission from
DDE is at least 100X less intense than that of DDD or DDT, and is
therefore more difficult to determine with adequate sensitivity.
Spectral differences among various Aroclors are sufficient to allow
those studied to be differentiated. Emission from solvent impurities
presently limit detection sensitivities to about 1. 0 ppm for DDT/DDD
and about . 01 ppm for Aroclors. By removing interference, detection
sensitivities should be improved by two orders of magnitude.
Low temperature luminescence studies in various binary mixtures of
Aroclor 1254 and p,p'-DDT indicate Aroclor 1254 maybe identified
and quantitated in the presence of DDT concentrations 100X greater.
111
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CONTENTS
Section Page
I Conclusions 1
II Recommendations 3
III Introduction 5
IV Experimental Methods 7
V Pesticides 11
DDE 11
DDD and DDT 12
*
VI Polychlorinated Biphenyls (PCB's) 19
PCB Isomers 19
PCS Mixtures (Aroclors) 30
Photolysis of Aroclor 1254 42
Determination of Aroclor 1254 in Water 44
VII Analysis of Mixtures: Aroclor 1254 and p, p'-DDT 45
Standard Low Temperature Measurements 45
Phosphoroscopic Measurements 49
Photoselection (Polarization) Measurements 49
VIII Summary 53
PCB Isomers and Mixtures (Aroclors) 53
Pesticides 54
Aroclor/Pesticide Mixtures 54
IX Acknowledgments 57
X References 5°>
XI Appendix 61
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TABLES
No. Page
1 Average Number of Chlorine Atoms per Isomer
in Aroclors, n, and Possible Number of Isomers
Having n Chlorine Atoms, N(n) ZO
2 Major PCB Constituents of Aroclors 22
VII
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FIGURES
No. Page
1 Structural diagrams for biphenyl, p,p'-DDE, p,p'-
DDT, andp.p'-DDD 7
2 Numbering system for biphenyl substituents 8
3 Excitation/emission spectra of p, p'-DDE (100 ppm)
in methylcyclohexane (MCH) glass at 77° K 11
4 Excitation/emission spectra of p, p'-DDT (100 ppm)
in MCH glass at 77° K 13
5 Excitation/emission spectra of o,p'-DDT (100 ppm)
in MCH glass at 77° K ' 13
6 Excitation/emission spectra of p, p1-DDD (100 ppm)
in MCH glass at 77° K 14
7 Excitation/emission spectra of o, p'-DDD (100 ppm)
in MCH glass at 77° K 14
8 Excitation/emission spectra of p, p'-DDT (10 ppm)
in MCH glass at 77° K 15
9 Excitation/emission spectra of o, p'-DDT (10 ppm)
in MCH glass at 77° K 15
10 Excitation/emission spectra of p, p1-DDD (10 ppm)
in MCH glass at 77° K 16
11 Excitation/emission spectra of o, p1-DDD (10 ppm)
in MCH glass at 77° K 16
12 Excitation/emission spectra of biphenyl, 2-chloro-
biphenyl, and 4-chlorobiphenyl (all 100 ppm) in MCH
glass at 77° K 24
13 Excitation/emission spectra of 4, 4"-dichlorobiphenyl
(1 00 ppm) in MCH glass at 77° K 24
IX
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FIGURES (Continued)
No. Page
14 Excitation /emission spectra of biphenyl, 2, 5, 2', 5'-
tetrachlorobiphenyl and 2, 4, 5, 2', 5' -pentachlorobiphenyl
(all 100 ppm) in MCH glass at 77° K 25
1 5 Excitation/emission spectra of 2, 5, 21, 5' -tetrachloro-
biphenyl and 2, 4, 5, 2', 41, 5' -hexachlorobiphenyl
(Hutzinger samples, 100 ppm) in MCH at 77° K 25
16 Excitation/emission spectra of biphenyl (100 ppm)
in heptane at 77° K 26
17 Excitation/emission spectra of 2-chlorobiphenyl
(100 ppm) in heptane at 77° K 26
18 Excitation/emission spectra of 4-chlorobiphenyl
(100 ppm) in heptane at 77° K 27
19 Excitation/emission spectra of 4, 41-dichlorobiphenyl
(1 00 ppm) in heptane at 77° K 27
20 Excitation/emission spectra of 2, 5, 2', 5' -tetrachloro-
biphenyl (100 ppm) in heptane at 77° K 28
21 Excitation/emission spectra of 2,4, 5, 21, 5' -penta-
chlorobiphenyl (100 ppm) in heptane at 77° K 28
22 Excitation/emission spectra of biphenyl and 2, 5, 2", 5' -
tetrachlorobiphenyl (both 100 ppm) in octane at 77° K 29
23 Excitation/emission spectra of biphenyl and 2, 5, 2', 5' -
tetrachlorobiphenyl (both 100 ppm) in nonane at 77° K 29
24 Excitation/emission spectra of Aroclors 1221 and 1248
(both 100 ppm) in MCH glass at 77° K 31
25 Excitation/emission spectra of Aroclor 1248 (100 ppm)
in heptane at 77° K 31
26 Excitation/emission spectra of Aroclor 1221 (100 ppm)
in heptane at 77° K 32
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FIGURES (Continued)
No. Page
27 Emission spectrum of a mixture of biphenyl (50 ppm)
and 4-chlorobiphenyl (50 ppm) in heptane at 77° K 32
28 Excitation/emission spectra of Aroclor 1254 (100 ppm)
in MCH glass at 77° K 33
29 Excitation/emission spectra of Aroclor 1221 (N, 100 ppm)
in MCH at 77° K 35
30 Excitation/emission spectra of Aroclor 1221 (N, 10 ppm)
in MCH at 77° K 35
t
31 Excitation/emission spectra of Aroclor 1242 (N, 100 ppm)
in MCH at 77° K 36
32 Excitation/emission spectra of Aroclor 1242 (N, 10 ppm)
in MCH at 77° K 36
33 Excitation/emission spectra of Aroclor 1248 (N, 100 ppm)
in MCH at 77° K 37
34 Excitation/emission spectra of Aroclor 1248 (N, 10 ppm)
in MCH at 77° K 37
35 Excitation/emission spectra of Aroclor 1248 (N, 1 ppm)
in MCH at 77° K 38
36 Excitation/emission spectra of Aroclor 1248 (N, 0. 1 ppm)
in MCH at 77° K 38
37 Excitation/emission spectra of Aroclor 1254 (N, 100 ppm)
in MCH at 77° K 39
38 Excitation/emission spectra of Aroclor 1254 (N, 10 ppm)
in MCH at 77° K 39
39 Excitation/emission spectra of Aroclor 1260 (N, 100 ppm)
in MCH at 77° K 40
40 Excitation/emission spectra of Aroclor 1260 (N, 10 ppm)
in MCH at 77° K 40
XI
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FIGURES (Continued)
No. Page
41 Excitation/emission spectra of Aroclor 1260 (N, 1 ppm)
in MCH at 77° K 41
42 Excitation/emission spectra of Aroclor 1260 {N, 0. 1 ppm)
in MCH at 77° K 41
43 Excitation/emission spectra of 4, 4'-dichlorobiphenyl
(100 ppm) photolyzed Aroclor 1254 (originally 100 ppm)
in ethanol at 77° K 43
44 Excitation/emission spectra of a mixture of p, p'-DDT
(50 ppm) and Aroclor 1254 (50 ppm) in MCH glass at
77° K 46
45 Excitation/emission spectra of a mixture of p, p1 -DDT
(50 ppm) and Aroclor 1254 (5 ppm) in MCH glass at
77° K 46
46 Excitation/emission spectra of a mixture of p, p'-DDT
(50 ppm) and Aroclor 1254 (0. 5 ppm) in MCH glass at
77°K 47
47 Excitation/emission spectra of a mixture of p, p' -DDT
(5 ppm) and Aroclor 1254 (5 ppm) in MCH glass at
77°K 47
48 Excitation/emission spectra of a mixture of p, p'-DDT
(5 ppm) and Aroclor 1254 (N, 0. 5 ppm) in MCH glass
at 77° K 48
49 Excitation/emission spectra of a mixture of p, p'-DDT
(5 ppm) and Aroclor 1254 (N, 0. 05 ppm) in MCH glass
at 77° K 48
50 Polarized excitation spectra of a mixture of Aroclor
1254 (5 ppm) and p, p1 -DDT (50 ppm) in MCH glass at
77°K 50
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SECTION I
CONCLUSIONS
1. A six month exploratory study has demonstrated that, using low
temperature luminescence methods, polychlorinated biphenyls {PCB1 s)
can be determined in the presence of much higher concentrations of
DDT-type compounds.
Z. The results obtained indicate that a simple, sensitive analytical
method for PCB1 s can be based on these methods.
3. Such a method would be fairly rapid and might be used either
independently or as an adjunct to standard methods employing gas
chromatography.
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SECTION II
RECOMMENDATIONS
1. It is recommended that this exploratory study be followed by a
program which will both continue basic studies and establish a simple
method for the estimation of PCB1 s in natural waters. Additional
PCB isomers should be studied in order to define sources of Aroclor
emission and to establish extent of energy transfer among PCB isomers.
Energy-transfer studies involving PCB mixtures and pesticides should
be continued.
2. More study should be devoted to adjunct methods which may prove
valuable in an analytical methodology for PGB" s/DDT' s by selectively
enhancing certain components. Such studies would involve photochemi-
cal experiments, phosphoroscopic methods (differentiation based upon
phosphorescence lifetimes), and photoselection methods (differentia-
tion based upon behavior with respect to polarized light).
3. A greater variety of Aroclor/pesticide mixtures covering a wide
range of concentrations, should be studied in order to establish detec-
tion limits and analytical curves.
4. It is recommended that an independent analytical method for PCB1 s
in the presence of pesticides based on low temperature luminescence
methods be developed.
5. The utility of low temperature luminescence methods as an adjunct
to gas chromatography for analysis of PCB's/pesticides should be
explored.
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SECTION III
INTRODUCTION
It has been known for some time that polychlorinated biphenyls (PCB1 si
interfere with the determination of DDT and similar pesticides in
standard methods utilizing gas chromatography.l • ^ These groups,
pesticides and PCB's, must be separated prior to quantification by GC,
the usual methods being column or thin-layer chromatography.3
PCB's have been widely used as plasticizers, solvents, and insulators,
and have, themselves, become ubiquitous environmental contaminants.^
These compounds are highly toxic to some species: exposure for 48
hours to . 1 ppm Aroclor 1254 (a commercial PCB mixture) in sea
water causes 100% mortality in juvenile pink shrimp. 5 Zitko and
Choi," Reynolds,^ and Risebrough' have reviewed PCB levels in fish
and fish-eating birds. These levels typically range from approxi-
mately . 01 ppm to 1 0 ppm in fish, 1 ppm to 100 ppm in birds, and in
fact are comparable to levels of DDE found in the same animals. PCB
levels in the range 100 to 200 ppm may be responsible for deformities
found in terns on Great Gull Island in Long Island Sound.° Thus, the
related problem of detecting pesticides in the presence of equal or
greater concentrations of PCB1 s may become important. Low tem-
perature molecular luminescence appeared to offer a potentially useful
method for the determination of PCB' s in the presence of DDT-type
compounds, and a six month exploratory study was initiated in order
to assess this approach. The results obtained are highly encouraging
and dramatically demonstrate the potential utility of this technique for
PCB's, DDT analogues, and PCB-DDT mixtures. The technique is of
greater applicability, and could in principle be applied to a wide vari-
ety of compounds such as chlorinated naphthalenes (Halowaxes), herbi-
cides such as 2,4, 5-trichlorophenoxyacetic acid (2,4, 5-T), poly-
brominated biphenyls (PBB1 s) and the highly toxic chlorinated dibenzo-
furans and dibenzo-p-dioxins.6 Luminescence methods are inherently
insensitive to saturated compounds such as endrin and dieldrin, so that
interferences which might exist in other methods such as GC are
eliminated.
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SECTION IV
EXPERIMENTAL METHODS
Figure 1 gives the structures of biphenyl, p, p'-DDT, p,p'-DDD, and
p,p'-DDE.
\
Biphenyl
Cl Cl
Cl C Cl
Cl
p,p'-DDT
Figure 1. Structural diagrams for biphenyl, p, p«-DDE, p,p'-DDT,
and p, p1 -DDD
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Figure 2 shows the numbering system defining the location of
substituents in biphenyl; this will become important in SECTION VI
where luminescence spectra of some chlorinated biphenyl isomers are
discussed.
2' 3'
3 2
Figure 2. Numbering system for biphenyl substituents
Both p, p1 - and o, p' -isomers of DDD, DDT, and DDE have been studied
to date. All of these compounds were obtained from the EPA Perrine
Primate Research Branch, Perrine, Florida.
PCB isomers studied initially were biphenyl, 2-chlorobiphenyl, 4,4'-
dichloro-, 2, 5, 2', 5' -tetrachloro-, and 2, 4, 5, 2', 5' -pentachloro-
biphenyl. All of these isomer samples (except biphenyl) were gener-
ously donated by Dr. R. G. Webb of the EPA Laboratory, Athens,
Georgia. Biphenyl was obtained from the Aldrich Chemical Company.
More recently, Dr. O. Hutzinger provided us with samples of 2, 5,2', 5'
tetrachloro- and 2, 4, 5, 2', 4', 5" -hexachlorobiphenyl, and the lumines-
cence signatures of these isomers have been included in this report.
Aroclor samples studied initially were 1221, 1248, and 1254. The
first two samples •were provided by the Monsanto Chemical Company,
and the last was supplied by Dr. Webb. Dr. E. S. Tucker of Monsanto
recently (27 October 1971) provided new samples of the following
Aroclors: 1221, 1242, 1248, 1254, and 1260.
Benzene, hexane, heptane, and methylcyclohexane were Matheson,
Coleman, and Bell Spectroquality Grade solvents. Octane, Chromato-
quality Grade, was obtained from Analabs, Inc. Nonane was obtained
from Eastman Chemical Co. Ethylene glycol was Matheson, Coleman,
and Bell Chromatography Grade. Ethanol was obtained from Graves
Distilling Company and was the Extra Fine Grade.
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All solvents were used as received, although attempts were made to
purify methylcyclohexane (MCH) using column chromatography (CC).
Initial studies employed a 24 in. long, 1 in. diameter glass column
packed with Woelm silica gel (Activity Grade 1) as the upper layer and
Woelm basic alumina (Activity Grade 1) as the lower layer. Passage
of Matheson Spectroquality methylcyclohexane through this column
revealed unidentified fluorescent contaminants which were not present
prior to the chromatographic operation. Further studies are necessary
with each packing material separately to determine the source of con-
tamination. Gather purification schemes, such as distillation, are
under consideration should problems associated with CC prove difficult
to correct.
As discussed in the original proposal, the room temperature
fluorescence/excitation spectra of PCB's and DDT-type compounds
overlap and thus result in interference. At low temperature (77° K),
however, phosphorescence appears and spectral overlap is much
reduced, allowing PCB's and DDT's to be selectively determined.
For this reason, our efforts have largely focused on low-temperature
measurement.
Sample tubes used for low-temperature measurements were 3mm
(inside diameter) Suprasil quartz tubes capped to prevent solvent
evaporation or contamination. Sample volumes of . 3 - . 5 mis were
transferred into the quartz tubes with disposable pipettes. Samples
were then frozen by direct immersion into a quartz dewar filled with
liquid nitrogen (boiling point 77° K) positioned in the Fluorispec.
If samples are cooled to 77° K slowly enough (in approximately 2
minutes or more), a clear glass will usually result for both ethanol
and methylcyclohexane, provided that these solvents (and the quartz
tube) are adequately dry. In general, no special drying procedures
were necessary for these solvents in order to achieve the glassy state.
Residual distilled water remaining in tubes after cleaning could be
quickly removed by purging the tube with dry nitrogen gas. This
residual water, if not removed, usually results in cracked glasses,
particularly for methylcyclohexane.
All other solvents formed either cracked glasses or "snows," the
latter condition being more characteristic of the n-alkane matrices.
These matrices are highly scattering and thus may be less satisfactory
for quantitative determinations than the clear glasses. However, these
matrices often produce line-like ("quasilinear") spectral bands at low
temperatures (see APPENDIX) and thus may prove useful for qualita-
tive studies.
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Many other solvent systems have been found to result in clear low
temperature glasses, and the interested reader is referred to the
literature^' ^ for details. Methylcyclohexane (and ethanol) were
chosen for our studies primarily because they form glasses them-
selves.
Luminescence measurements were made on either the Baird-Atomic
SF-1 or SF-100 Fluorispec instruments. These instruments are
identical in their optical systems, the SF-100 having more modern
and versatile electronics. Most of the spectral data were obtained
with analyzing slits set at their smallest values to obtain the maximum
spectral resolution (2 nm). The standard source for these instruments
is a Hanovia 1 50 Watt (D. C. ) Xenon lamp, and the standard detector
is an RCA 1P28 photomultiplier tube.
Data obtained on the SF-1 instrument have been designated as such on
the appropriate figures; where no such designation appears, the SF-100
instrument has been used.
10
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SECTION V
PESTICIDES
Excitation and emission spectra have been obtained for p, p1 - and o,p'-
DDE, ODD, and DDT in methylcyclohexane (MCH) glass at 77° K.
Concentrations ranged from 1 to 100 ppm. Near 1 ppm, interference
from emitting solvent impurities becomes significant and solvents of
higher purity must be used in order to exceed this limit.
DDE
A freshly prepared solution of p, p1-DDE at a concentration of 100 ppm
in MCH at 77° K shows a very weak, broad emission band in the region
310 - 440 nm with a maximum at approximately 370 nm (Figure 3).
WAVELENGTH (nonom«l««|
Figure 3. Excitation/emission spectra of p, p1-DDE (100 ppm)
in methylcyclohexane (MCH) glass at 77° K
The corresponding excitation occurs in the 300 - 280 nm region with a
maximum at 294 nm. A similar solution of o,p' -DDE studied at the
same approximate wavelengths shows no evidence of emission. The
observed p, p1-DDE emission is roughly 400X less intense than that of
the DDD or DDT phosphorescence.
11
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These results differ from those presented in the fourth monthly
report, and the earlier results may have been influenced by photo-
products formed upon standing in the presence of room lights for
several months. The present results again differ from those of Moye
and Winefordner,H who report a phosphorescence maximum at 425 nm
and corresponding excitation maxima at 270 and 245 nm for p, p1 -DDE
in ethanol at 77° K. The results quoted by these authors for p, p1-DDE
are very similar to their values for p.p'-DDD and p, p1-DDT: excita-
tion maxima at 265 and 275 nm and phosphorescence maxima at 415
and 420nm respectively in ethanol at 77° K. In addition, the phosphor-
escence detection limits given by Moye and Winefordner for all these
compounds are roughly the same (within a factor of 5) and imply that
the DDE emission should be much stronger than we observe.
At the present time, we believe that the low temperature DDE emission
is intrinsically much weaker than that of DDD or DDT. It is not cer-
tain, however, if the emission shown in Figure 3 is actually that of
p,p' -DDE or is in fact due to an impurity in DDE.
DDD and DDT
Excitation and emission spectra of the four DDD and DDT compounds
{100 ppm in MCH) are very similar as shown in Figures 4 through 7.
The phosphorescence origins are in the region 355 - 366nm. The band
systems are slightly structured to the short-wavelength side of the
maximum but become stronger and more diffuse at longer wavelengths.
No evidence of fluorescence was observed in these compounds. The
excitation spectra show prominent, narrow (3 - 4 nm half-widths) origin
bands at 275 - 277 nm followed by several other weaker and slightly
broader bands. A second system, presumably due to a different elec-
tronic transition, appears at 240-246nm. Our results onp,p'-DDD
and p, p'-DDT are in general consistent with the data of reference 11,
and the excitation spectra resemble the absorption spectrum of the
parent hydrocarbon, diphenyl methane as given by Berlman. 12
Spectra of these same compounds at a concentration of 10 ppm in MCH
appear in Figures 8 through 11. The additional emission which appears,
particularly in the DDD spectra, is due to impurities present in the
pesticide samples. The reason that the impurity emission becomes
relatively more intense at lower concentrations is due to the phenom-
enon of energy transfer. At high solute concentrations, impurities
can efficiently transfer their excitation energy to the major emitting
component (the pesticide). At reduced concentrations energy transfer
becomes less favorable and it is more likely that the impurities will
emit rather than transfer excitation energy.
12
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SAMPU: p,p' -DOT.
CONCENTRATION I00pj»r, In
MCH.
SLITS 11/22 E*. & 22/11 Em.
TIME CONSTANT O.I UK.
RECORDER 0.01 MAX
TEMPERATURE 77°K
GAIN 30/8
EXCITATION WAVELENGTH 272nm
EMISSION WAVELENGTH 402™
GAIN 30/B 4 10/8
Z S
-Ltao-
WAVELENGTH(rx»Kxii«ten)
Figure 4. Excitation/emiaaion spectra of p.p' -DDT (100 ppml
in MCH gla»« at IT K
SAMPLE: o,p' - DDT.
CONCENTRATION lOOppm in MCH
SLITS 11/22 Ex. & 22/11 Em.
TIME CONSTANT 0.3»«c.
RECORDER 0.01 MAX
TEMPERATURE 77°K
GAIN 100/7
EXCITATION WAVELENGTH 274r«n
EMISSION WAVELENGTH 405nm
GAIN IW/7 & 30/7
WAVELENGTH (naxxMt Ml)
Figure 5. Excitation/omiiiian spectra of o.p'-DDT (100 ppml
In MCH gl»M. »t 77- K
13
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SAMPLE: p,p' -ODD.
CONCENTRATION lOOppm In MCH
SLITS 11/22 Ex. 122/11 Em.
TIME CONSTANT 0.3»c.
; RECORDED 0.01 MAX
TEMPBATURE 77°K
GAIN HO/7
EXCITATION WAVBJENGTH TT*m
EMISSION WAVaENGTM 40fe»
MAVaENGTH(nanomi»in)
Figure 6. Excitatioo/emiMioB cpcctra of p.p'-DDD (100 ppm)
in MCH gU«. »t 77-K
SAMPLE: o,p'-DDD.
CONCENRATION lOOpprr, inMCH.
SLITS 11/22 Ex. 122/11 Em.
TIME CONSTANT 0.3«>e.
RECORDER 0.01 MAX
TEMPERATURE 77°K
GAIN 100/7
EXCITATION WAVELENGTH 276nm
EMISSION WAVELENGTH 408nm
GAIN 100/7 130/7
WAVRENGTH(nano>n«t«n)
Figure 7. Ebtcitation/ciniaaion apectra of o.p'-DDD (100 ppm)
in MCH ll».» at 77" K
14
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Sompl.: P,P - DD1
Covcentnjtlorn I0p»» in MCH
SUM U/33 E>. i M/n b-
Tim* Cantor*
I.eonUr
Coin
Temperature
bniulan
E>c!to*lan Mavtlmgth 272
Gain 100/9
Fifur* ft. Excit»tlon/«mi»i*ion cpectra o£p,p'-DDT (10 ppmt
in MCH gUn »t.77-K
Excitation ,Vav«lenjtn 274it>n >p«ctr> of o, p' -DDT (10 ppm)
la MCHgU.i »t77'K
15
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Sample p.p' -ODD
Concentration! 10 ppm In MCH
Silt, 11/33 E«. 433/H Em.
Time Comtant 0.3iee.
Recorder 0.01 Mo.
Gain 100/1 at 410 & 30/7 ot440nm.
Temperature
Emlulon Wavelength 410, 440nm.
Excitation Wavelength 27Snm
Gain 100/3
Figure 10. Excitmtion/emiiilon apectra of p, p'-DDD (10 ppm)
in MCH gl»«« »t 77-K
UJ
I
>
>-
o,p'-DDD
10 ppm in MCH
III* 11/33 EM. & 33/11 EX.
Tbw Cemtont 0.3«ec.
0.0) MAX
0»t» 100/1
77»K
velength 407 nm
bckejlon Wavelength 274 nm
1 0««" 100/3
400 500
WAVELENGTH (nanometen )
Figure 11. Excit*tloB/omi»ion ipectrc at o,p'-DDD (10 ppm)
In MCH gUli at 77- K
600
700
16
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Experiments were performed to determine the effect of dissolved
oxygen on the phosphorescence yield of p,p'-DDD and p, p'-DDT.
Solutions having concentrations of 1 0 ppm in MCH were studied at
77° K before and after bubbling dry, pure nitrogen gas through the
samples for about 5 minutes. No appreciable enhancement (greater
than 30%} was observed in the phosphorescence intensity after purging
the solutions. It is possible, however, that this method is inadequate
for the complete removal of oxygen, and a vacuum system is being
constructed in order to achieve better degassing (by allowing pump-
freeze-thaw cycles).
Preliminary studies on p,p' -DDT in heptane at 77° K reveal no
additional sharpening of the phosphorescence, in contrast with some
of the PCB isomers (SECTION VI). In addition, the phosphorescence
maximum of p,p' -DDT was found to shift from approximately 405nm
in MCH to approximately 455 nm in heptane.' Similarly, the excitation
band at 277 nm in MCH shifts to 290 nm in heptane. These spectral
differences may reflect changes in the DDT geometry in the two
matrices, and in particular may suggest that the relative orientation of
the DDT phenyl groups in the two matrices are rather different.
17
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SECTION VI
POLYCHLORINATED BIPHENYLS (PCB's)
PC B Isomer s
Commercial mixtures of polychlorinated biphenyls and terphenyls are
manufactured in the United States by the Monsanto Company under the
tradename "Aroclor. " Foreign manufacturers of similar products
include Prodelee in France (" Phenoclor"), Bayer in Germany
("Clophen"), with additional production in the USSR and Japan.
Monsanto uses a four digit code to specify Aroclor s. The first two
digits of the code designate the parent hydrocarbon type as follows:
12: Chlorinated biphenyls
25: Mixture of chlorinated biphenyls and chlorinated
terphenyls (75:25)
44: Mixture of chlorinated biphenyls and chlorinated
terphenyls (60:40)
54: Chlorinated terphenyls
The last two digits of the code designate the weight percentage of
organically bound chlorine. For example, Aroclor 1254 is a mixture
of chlorinated biphenyls having 54% chlorine.
A weight percentage of 54% chlorine implies that an "average" isomer
in this Aroclor has five chlorine substituents. For five chlorine atoms
per biphenyl a total of 46 isomers are statistically possible assuming
that conformations differing only by a possible angle of twist (0° to
180°) between phenyl groups are equivalent. Of course, this figure
does not represent the actual isomer content of this Aroclor, since
certain isomers are favored by the chlorination reaction, and the
occurrence of isomers having more or less than five chlorine atoms
is also possible. Table 1 summarizes the average number of chlorines
per biphenyl, n_v, in various Aroclors, the closest whole number
value of naV' n> an(* *^e statistically possible number of isomers, N,
having n chlorine atoms, N(n). The statistical calculation is subject to
the restraint noted previously. Aroclors in parentheses denote hypo-
thetical mixtures.
19
-------
Table 1. Average Number of Chlorine Atoms per Isomer in Aroclors,
n, and Possible Number of Isomers Having n Chlorine Atoms,
N(n)
Aroclor nav n
N(n)
(1200) 0.0 0 1
1221 1.2 1 3
1232 2.0 2 12
1242 3. 1 3 24
1248 3.9 4 42
1254 4.9 5 46
1260 6.3 6 42
1262 6.8 7 24
(1266) 8.0 8 12
1268 8.7 9 3
(1271) 10.0 10 1
From Table 1, there is a total of 210 PCB isomers possible statistically
having from zero to ten chlorine atoms. Hence the problem of estab-
lishing the isomer distribution in a given Aroclor is very difficult, and
only recently has progress been made.
Webb and McCall^ ^ have identified 30 PCB isomers in Aroclors 1221,
1232, 1242, 1248 and 1254 by comparison of GC retention times and
IR spectra with those of isomers prepared by the Gomberg or Ullmann
reactions. Sissons and Welti^ have performed a similar study on
Aroclor 1254 utilizing NMR and mass spectroscopy data obtained on
40 isomers; GC retention indices were used to predict the isomer com-
ponents of Aroclor 1242 and 1260. Tas and deVos^ have established
four major components of Phenoclor DP6 (a mixture similar to Aroclor
1260) using NMR and IR spectra of these isomers prepared by the
Ullmann reaction. Hutzinger, et_aL ,16 have reported the synthesis of
many PCB isomers so that further work on identification of isomers in
Aroclors may be forthcoming from these and other laboratories.
Table 2 summarizes the major components of Aroclors and Phenoclor
DP6 as determined by Webb and McCall, Sissons and Welti, and Tas
and deVos.
20
-------
Important isomers available to us and thus chosen for study were:
biphenyl; 2- and 4-chlorobiphenyl; 4, 4'-dichlorobiphenyl; 2, 5,2', 5'-
tetrachlorobiphenyl; 2, 4, 5, 2', 51-pentachlorobiphenyl; and 2, 4, 5, 2', 4', 5'
hexachlorobiphenyl. These compounds appear underlined in Table 2.
Figures 12 through 15 show spectra of the isomers in MCH at 77° K.
Spectra of the isomers in heptane at 77° K appear in Figures 1 6 through
21. Figures 22 and 23 show spectra of biphenyl and 2, 5, 2' , 5' -tetra-
chlorobiphenyl in octane and nonane respectively. Where composites
have been used, the spectrum of one isomer has been vertically dis-
placed for clarity.
Part of the isomer study included an investigation of several solvents to
determine possible solvent effects upon spectral bandwidths. Excita-
tion and emission spectra of biphenyl were obtained in the following
matrices at 77° K: hexane, heptane, octane, nonane, benzene, MCH,
and ethylene glycol: water (2:1 by volume). Only MCH formed a clear
glass upon cooling rapidly (approximately two minutes) to 77° K. Ethyl-
ene glycol: water formed a cracked glass and some of the biphenyl
remained insoluble, but this presented no special difficulty. The other
solvents used, particularly the alkanes, formed "snows" and hence the
scatter was greatly increased.
As expected from the early work of Shpolskii,* ' the biphenyl emission
at 77° K was found to be sharpest in the n-alkane matrices. A brief
account of the conditions favoring this so-called "Shpolskii" effect
appears in the APPENDIX. In particular, the biphenyl emission was
extremely sharp (half width of 2 - 4nm) and highly detailed in heptane
(Figure 16) and hexane. Band widths may in fact be slit limited in
these matrices. Heptane was found to produce a barely perceptible
narrowing over hexane. Spectra obtained in the remaining solvents
were broader (half widths approximately 20nm) and typically resembled
those observed in MCH (Figure 12).
The spectra in octane and nonane (Figures 22 and 23) were broader,
the biphenyl origin band having an approximate half widths of 6 and
1 0 nm respectively. The spectrum of biphenyl in octane reveals a
broad emission at about 390 nm which may be due to biphenyl aggre-
gates (see APPENDIX).
Isomer spectra were obtained in several solvents, leading to the
following conclusions:
a) The ratio of fluorescence to phosphorescence is reduced upon
chlorination: for biphenyl, the uncorrected ratio of fluorescence to
21
-------
Table 2. Major PCB Constituents of Aroclors'
1260 (DP6)
Biphenyl
2^
4^
2,2'-
2,3'-
2,4'-
4, 4' _
2,3,2'-
2,3,3'-
2,4,2'-
2,4,3'-
2,4,4'-
2,5,2'-
2,5,3'-
2,5,4'-
2,6,4'-
3,4,2'-
2,3,2',5'-
2,4,2',5'-
2,4,3',4'-
2.5.2'.5'-
2, 5,3'. 4'-
2,3,4,3'-
2, 3, 4, 2', 5'
2, 3, 4,3', 4'
2,3, 6,2', 3'
2,3, 6,2', 5'- S* W, S* S*
22
1221 1232 1242
W W
W W W
W W
W W W, S
W W,S
W W W, S
W
W W, S*
W, S
S
W, S*
W W, S
S*
W
S
w,s
W
S*
W
W, S*
W, S
S*
S*
1248 1254
W
W
W
W W, S*
W
W
W W, S*
W S
S
S
W W, S
W, S*
-------
Table 2. Major PCB Constituents of Arodors' (cont. )
1221 1232 1242 1248 1254 1260 (DP6)
2, 3, 6, 2'. 6'- W
2, 3, 6, 3'. 4'- S*
2,4,5,2',3'- W, S
2,4, 5, 2',4'- W, S*
2,4, 5,2', 5'- W W, S* S*
2,4, 5,3',4'- ' W, S
2, 3, 4, 2', 3', 4'- S
2, 3,4,2', 3', 61- , S S*
2, 3,4,2', 4', 5'- S* S*.(T)
2, 3, 5, 2', 4', 6'- S*
2,3, 6, 2', 3', 6'- S
2, 3, 6,2'. 4', 5'- W, S* S*
2.4,5,2',4'.5'- W,S* S*,(T)
2,3,4,5,2',3',4'- S*,(T)
2,3,4,5,2'.4', 5'- S, (T)
2, 3, 4, 5, 2'. 4', 6'- S*
2, 3, 4, 6, 2', 3', 5'- S*
2,3,5, 6, 2', 3',4'- S*
f Data from References 13 (W), 14 (S), and 15 (T).
* Denotes alternative assignments are possible.
23
-------
SAMPLES: BIPHENYL, 2CL-BIPHENYL
4CL-BIPHENYL
CONCENTRATION 100 pom in MC H
SLITS 21/12
TIME CONSTANT 0.3 IK .
RECORDER 0.01 MAX
TEMPERATURE 77<>K.
BIPHENYL ( SOLID CURVE)
GAIN 10/10
EXCITATION WAVELENGTH 280nm
EMISSION WAVELENGTH 460 rvr,
2CL-BIPHENYL ( DOHED LINE ...)
GAIN 10/10
EXCITATION WAVELENGTH 272nm
EMISSION WAVELENGTH 460 nm
200
4CL-BIPHENYL ( )
GAIN 10/10
EXCITATION WAVELENGTH 280 n
EMISSION WAVELENGTH 470nm
GAIN 3/lp
400 500
WAVELENGTH(nonomot.n)
Figure 12. Excitation/emiasion spectra of biphenyl, Z-chlorobiphenyl.
»nd 4-chlorobiphenyl (all 100 ppml in MCH gla» at 77-K
SAMPLE: 4,4'-CI-Blph«nyl
CONCENTRATION lOOppm In MCH.
SLITS 21/12
TIME CONSTANT 0.03 we.
RECORDER 0.01 MAX
TEMPERATURE 77<>K
GAIN 3/10 & 30/10
EXCITATION WAVELENGTH 282nm.
EMISSION WAVELENGTH 4*Jnm,
GAIN 3/10
j|l||i||||||||g^|
700
Figure 13. Excltitlon/emU«lon >pectr> of 4, 4'-dlchlorobiph>Dyl
(100 ppm) in MCH glmil at IT K
24
-------
iAMPltS BlfHENYL. ZST
2Xi?;'rlL- SIPHENrl
CONCENTRATION IQOppn in MCH
SLITS 21/12
: TIME CONSTANT 0.3i«c.
• ECOtOEJ 0.01 MAX
TEMfHLATUH 77»1C.
BtPHENYl (SCHOCUIVE)
GAIN 10/V>
EXCITATION WAVRENGTH _
EMISSION WAVELENGTH 46C*_
GAM U/ID
. EXOTAHON **"> in MCH glass .1 77- K
jaUBOnlDMIC
SAMFUS: 2,5,2',5'CI-BIPHENYl.
2,4,5,2'/«1,5'CI-BIPHENYL
CONCENTRATION: lOOppn. in MCH
INSTRUMENT: SF-1
SLITS 11/22 Ex. & 22/11 Em.
TIME CONSTANT O.I UK:.
IECORDER 0.01 Mo.
TEMPERATURE 77°K.
2,5,2',5'CI-BIPHENYL (SO.ID CURVE)
GAIN 100/4.0
EXCITATION WAVELENGTH 2VOn«.
EMISSION WAVELENGTH 444nm
GAIN 100/7.0
2,4,5,2',4',5'CI-BIPHENYL ( !
GAIN 10/10.0
EXCITATION WAVELENGTH 297nm
EMISSION WAVELENGTH 445nm
GAIN 100/2.0
WAVELENGTH ( no.xjm.lcn)
Pifure 15. E^clUllon/cmliilon >pcctr> of 2. 5. Z1. 5' -tetr»-
chlorobipbearl and 2,4. 5, 2'. 4'. 5' -hexmchloro-
l (Hutilnger »mple>, 100 ppml in MCH >l 77* K
25
-------
IBAIBD ATOMIC]
SAMPLE: BIPHENYL
CONCENTRATION lOOppm In HEPTANE
SLITS M/22EX. & 22/11 EM.
TIME CONSTANT 0.3 ue.
RECORDER 0.01 MAX
TEMPERATURE 77°K.
GAIN 3/10
EXCITATION WAVELENGTH 4t7m
EMISSION WAVELENGTH 276™n
BASELINE SOLVENT HEPTANE
SLITS 22/11
GAIN 30/10
EXCITATION WAVELENGTH 276nm
200
300
400 WAVELENGTH(neMiomeSfl9)
600
Figure 16. Excitation/emission spectra of biphenyl (100 ppm)
in heptane at 77" K
700
SAMPLE XL- BIPHENYL
CONCENTRATION lOOppnt
In HEPTANE
SLITS 11/22 EX. & 22/11 EM.
TIME CONSTANT 0.3 we.
RECORDER 0.01 MAX.
TEMPERATURE 77°*.
GAIN 30/5
EXCITATION WAVELENGTH 27Snm
EMISSION WAVELENGTH
700
Excitation/emiBlion spectra of 2-chlorobiplMnyl (100 ppm)
In heptane at IT K
Z6
-------
SAMB.E 4CL-SIPHENYL
CONCENTKATION 100 pp. In HECTANC
SLITS 11/22 EX. & 22/11 EM
TIMl CONSTANT 0.3 MC.
tKC*OE* 0.01 MAX
TIMWATLBE 77°IC.
GAIN 1/7
EXCITATION WAVELENGTH 31
EMISSION "AvaENGTH
GAIN 3/7 & 10/7
Z
s
IAJ
I
200
300 40° «AVELENGTH(nonomt^(ft
Figur* 18. C3iclt«tion/enii««ion apectra of 4-chloroblph«nyI
(100 ppm) in heptane, at 77" K
600
iBUHO-AlDMICli
SAMHE: 4,4' n.
GAIN 100/626
»VAVUENGTH(nonom«t«n)
Figure 19. Exclt«titin/«ml«iion ipectra o< 4.4'-dtchlorobiph«nyI
(100 ppm) In hept.n. at 77* K
27
-------
SAMPLE 2J2'5'-CL-BIPHENYL
CONCENTRATION lOOppn
n HEPTANE
SLITS 11/22 EX. & 22/11 EM.
TIME CONSTANT 0.3 iac
RECORDED 0.01 MAX.
TEMPERATURE 77°K.
GAIN 10/6
EXCITATION WAVELENGTH 285
EMISSION WAVELENGTH «7nm
GAIN 10/8 & 100/8
Figure 20. Excitation/emiaaion apectra of 2. 5, 2'. 5' -tatrachloro-
biphenyl (100 ppm) in heptane at 77* K
SAMPLI WTF<1- IIPHENYL
CONC«NTtATtON~aillm/7 4 We/7
4i-- ^
Fl(ur« 21. Excltatlof»/«irtl»»ion apectra of 2, 4. 5, 2', 5' -pentachloro-
biph.nyl (100 ppm) in heptan. at 77* K
28
-------
SAMPLES: HfHtMYL, 2,5, 2',5'-CI-
6IPHENYL, OCTANE
CONCENTRATION: 100pc«n in OCTANE
CLITS: 11/22 Ex & 22/11 Em.
TIME CONSTANT O.I nc
RECORDER 0.01 Mo.
TEMPERATURE 77°K.
BIPHENYL ( SOLID CURVE I
OAIN 30/7
EXCITATION WAVELENGTH 272rm.
-f-f EMISSION WAVELENGTH *40om.
GAIN 30/10
8IPHENYL ( -.-.-.-.-. )
GAM 10/10
EMISSION WAVELENGTH 390™,.
2,5,2',5'-CI-BIPHENYL ( I
GAIN 10/8
EXCITATION WAVELENGTH 2S5nm.
EMISSION WAVELENGTH *40
OCTANE (
GAIN 30/10
EXCITATION WAVELENGTH 272nir
EMISSION WAVELENGTH 390nm.
t • "•• ' : -• : -;
WAVELENGTH ( nonometefl )
Figure ii. Excitation/emission spectra of biphenyl and I, 5, 2*, 5' -
tetrachlorobiphenyl (both 100 ppm) in octane at 77" K
333 SAMPLES: BIPHENYL, 2,5.2',5'CI-
BIPHENYL, NONANE
CONCENTRATION: lOOppm in NONANE
SLITS: 11/22 E». & 2Z/M Em.
TIME CONSTANT O.I we.
RECORDER 0.01 Mcu.
TEMPERATURE 77°K.
BIPHENYL (SOLID CURVE)
GAIN 30/10
EXCITATION WAVELENGTH 272nm
EMISSION WAVELENGTH 470nm
"2,5,2',5'CI-BIPHENYL ( )
GAIN 10/10
EXCITATION WAVELENGTH 2B5nm
, EMISSION WAVELENGTH 440nm
3s NONANE ( )
' " _ . 30/10
EXCITATION WAVELENGTH 272nm
EMISSION WAVELENGTH 350™n
I
i=
300
Figure
400 500
WAVELENGTH ( nonom.t.n)
Excitmtton/emiiaion spectra of biphenyl and 2. 5,2'. V -
tetrachlorobiphenyl (both 100 ppm) in nonane at 77* K
-------
phosphorescence is about 1:3, while in the chlorinated compounds this
is reduced by factors of 10 - 100. This phenomenon is possibly due to
an enhancement of intersystem crossing rates by the chlorine substit-
uents, favoring the formation of phosphorescent triplet states. °» *°
b) In MCH, the emission intensity for the two isomers having a
chlorine substituent at the 4-position is stronger by a factor of three or
four than for the other compounds, and may reflect the higher oscillator
strengths expected theoretically. "
c) In heptane, the emission of biphenyl, 4-chlorobiphenyl and 4, 41 -
dichlorobiphenyl show the greatest amount of structure (Figures 16,
18, and 19). The 2-chlorobiphenyl isomer (Figure 17) shows some
structure overlapping a diffuse background. The sharper system was
subsequently identified as being due to biphenyl impurity in the 2-
isomer; we estimate its relative abundance at about 1%. The tetra-
and pentachloro-compounds show rather diffuse emission in heptane
(Figures 20 and 21). The same general trends are also observed in
MCH, but in this solvent the sharp structure of the lower-chlorinated
isomers is largely obliterated (Figures 12 and 13).
d) In order to determine whether an n-alkane of longer chain length
would sharpen the spectra of a more highly chlorinated isomer,
spectra of 2, 5, 2", 5' -tetrachlorobiphenyl (Hutzinger sample) were
studied in octane and nonane (Figures 22 and 23). Neither solvent
noticeably sharpened the emission, and suggests that the emission of
this compound and perhaps others of high chlorine content may be
intrinsically diffuse.
e) Both in heptane and in MCH, the excitation spectra of 2, 5, 21, 5' -
tetrachloro- and 2,4, 5,2", 5'-pentachlorobiphenyl show two rather
narrow bands at 280 -290nm, followed by a second system at 245-
255 nm (Figures 14, 15, 20, 21). The spectrum of 2, 4, 5, 2', 4', 5'-
hexachlorobiphenyl in MCH is similar, except that the shorter wave-
length system has shifted to about 263nm (Figure 15). These features
are much less evident in the spectra of isomers having fewer chlorine
substituents; these compounds generally show only a single diffuse
band (Figures 12, 13, 16 through 19).
PCS Mixtures (Aroclorsj^
Initially, two Aroclors, 1221 and 1248, were studied in MCH and
heptane. Spectra are shown in Figures 24 through 27. The 1248
emission showed only very slight evidence of sharpening in the heptane
matrix (Figure 25). This is not unexpected since the components are
30
-------
Atociot rza
—M • HCH
•xm zz/«
m* CONSTANT 0.3 Me.
IKCtDE* O.CM MAX
AJOCLOR 122 I )
GAIN 3/10
EXCITATION WAVELENGTH 272™
EMISSION WAVELENGTH 320nm
ASOCLOR 1248 ( SOLID CURVE)
GAIN 3/10
EXCITATION WAVELENGTH 272nm
EMISSION WAVELENGTH 323™*
200
300
400
WAVELENGTHfnonomltSi)
Figure 24. Excitation/emission spectra of Aroclors 1221 and 1248
(both 100 ppm) in MCH glass at 77-K
600
700
SAMPLE AROCLOR 12*8
CONCENTRATION (OOppr
in HEPTANE
SLITS 11/22 EX. & 22/11 EM.
TIME CONSTANT 0.3 «ec
RECORDER 0.01 MAX
TEMPERATURE 77<>K
GAIN 10/7.5
EXCITATION WAVELENGTH 28t
EMISSION WAVELENGTH
GAIN 10/7.5 & 100/7.5
600
Figure 25. Excltation/emUiion ipectra of Aroclor U48 (100 ppm)
in heptane at 77- K
31
-------
BBAHHUOHB
SAMfU AJUXLOi 1221
CONCEN1IATION ttT%f i I KIT" 11C
SLITS 11/72 EX. ft 22/11 EM
TIME CONSTANT 0.3MC
BECORDER 0.01 MAX
TEMff RATURl 77°K
GAIN 3/V
EXCITAITION WAVELENGTH 28*™
EMISSION WAVELENGTH 480am
GAIN 3/9 & 30/9
I I I I Itt
600
700
Figure 26. Excitation/emisaion spectra of Aroclor 1221 (100 ppm)
in heptane at 77* K
SAMPLE MIXTURE Of UmENYt
SLITS 22/11 EMBS«OM
TIMt CONST AMI 0.1
BKOMWIO.aiMM.
TEMPBtATUtE TT^C.
GAIN
EXCITATION WAVELENGTH 2B4ran
200
! 27. Emiiiion spectrum of a iniztvre of biphenyl (50 ppm)
and 4-chlorobiphenyl (50 pptn) In heptane at 77* K
600
3Z
-------
more highly chlorinated, and the isomer emission spectra of two such
components are diffuse. The 1221 emission, however, revealed con-
siderable sharpening in heptane as opposed to MCH (Figures 24 and
26), again reflecting the predominance of the lower-chlorinated species.
In fact, both biphenyl and 4-chlorobiphenyl could be identified in
Aroclor 1221 by comparison with the isomer spectra. Figure 27 shows
the emission of a mixture of these isomers (each 50 ppm) in heptane at
77° K; from the spectrum of the Aroclor excited at the same wavelength
(Figure 26), one can estimate the relative amount of the 4-chloro-
isomer as being at least 50% and perhaps more. (More quantitative
estimates will be possible pending a better understanding of possible
energy transfer among isomers. Such studies are planned for the con-
tinuation of this program. )
Figure 28 shows spectra of Aroclor 1254 in MCH at 77° K. The
excitation spectrum monitored at 405 nm resembles that of either
2, 5, 2', 5' -tetrachloro- or 2, 4, 5, 2', 5' -pentachlorobiphenyl (Fig-
ures 14 and 15). Both of these isomers have been identified in Aroclor
1254 using GC (Table 2).
SAMPU: AHOCLOt 1254
CONCENTRATION lOOppn In MCh
SLITS 11/72 E». & 24,11 E*i.
TIME CONSTANT O.I uc.
RECORDS 0.01 MAX
TEMPERATURE 77°(c
GAIN 3/10 & 30/10
EXCITATION WAVELENGTH 2E5~r
EMISSKDN WAVELENGTH **4nm 1 4IOnm.
GAIN 3/10
. i '. I I
Figure 28. Excitation/emission spectra of Aroclor 1254 (100 ppm)
in MCH glass at 77° K
33
-------
Recently, excitation and emission spectra of Aroclors 1221, 1242,
1248, 1254, and 1260 (obtained 27 October 1971 from Dr. E. S. Tucker
of Monsanto) have been documented. All Aroclors were studied at 100
and 10 ppm in MCH at 77° K. Aroclors 1248 and 1260 were also studied
in the same solvent at concentrations of 1 and 0. 1 ppm. Spectra of
these "new" samples have been designated with an (N) in Figures 29
through 42. The spectra obtained are sufficiently different (partic-
ularly the excitation spectra) and could be used to distinguish the
various Aroclors. It is of interest to note the resemblance of the
Aroclor 1260.excitation spectrum (Figure 39) to that of 2, 4, 5, 2', 4', 5' -
hexachlorobiphenyl (Figure 15).
The spectra of the "new" Aroclors do not differ greatly from those of
the samples obtained earlier, although some differences are apparent.
These differences are due either to somewhat different isomer content
among different batches, or in the case of Figure 24, are due to the fact
that in some earlier traces the fluorescence region was monitored in
excitation and in the latter cases the phosphorescence region. Since the
contributing isomers will be different for these two regions (lower
chlorinated species dominate in fluorescence), so will the excitation
spectra differ.
Another effect is apparent in the Aroclors, namely the change in
structure of the excitation spectra upon dilution. Usually, the shorter
wavelength region intensifies and the apparent excitation maximum
shifts to shorter wavelengths. The first effect is largely a geometrical
effect; since the Aroclor is about 20 times more dense optically
(strongly absorbent) at 230nm than at 290nm, the shorter wavelength
radiation is absorbed much closer to the surface of the sample than is
the longer wavelength radiation. As a result, emission due to short
wavelength excitation originates at the surface while that due to longer
wavelengths originates throughout the sample. The normal geometry
of the instrument is such that emission occurring at or near the sample
surface is not collected as efficiently as is emission occurring near the
center of the sample, so that the apparent emission intensity produced
by radiation of shorter wavelength is less. As the sample is diluted,
penetration by the excitation beam becomes deeper at all wavelengths
and the geometrical factor becomes less apparent.
The second effect, viz., the apparent shift in the excitation maximum
to shorter wavelength upon dilution, is probably largely a geometric
effect, but may also reflect energy transfer among PCB isomers.
Energy transfer phenomena are expected to increase at higher solute
concentrations, and should favor emission from those isomers having
the lowest energy (longest wavelength) electronic transitions. As the
34
-------
Irutrvffnenf SF -I
Sample: ARGCLGR 1221 (N)
Concentration: lOOppm in MCH
Sllh 11/22 EX. & 22/11 EM.
Time Constant 0.1 vec
Recorder 0.01 >/i/
Gain 100/10
Temperature 77°K
fcmiiii-xi rtaveleogtn 476o*n .
L«clt
-------
ln.trum.ntSF -I
Somple: AROCLOR 1242 (N)
Concentration: lOOppm in MCH
Sll" 11/22 EX. & 22/11 EM.
Tim* Constant O.I iec.
Recorder 0.01 Max
Gain 410, 1000/4.0 , 452, 100/8.
Temperatur* 77°K
Emission Wavelength4)0, 452 nm.
Excitation Wavelength 282nm.
Gain 100/7.0 & 1000/7.0
... j_
I-;
±
;i
I
400 500
WAVELENGTH (nanomel.n)
Figure 31. Excitation/emUsion spectra of Aroclor 1242
(N, 100 ppm) in MCH at IT K
700
Instrument SF -1
Somple: AROCLOR 1242 (N)
Concentration: 10 ppm in MCH
Sllh 11/22 EX. & 22/11 EM.
Time Constant O.I tec .
Recorder 0.01 MAX
Gain Em. 410 1000/10, Em. 465 1000/6
Temperature 77°K.
Emission Wavelength 410 , &465nm.
WAVELENGTH (nanometers)
Figure 32. Excltation/emiaflion spectra of Aroclor 1242
(N, 10 ppm) in MCH at 77- K
36
-------
SF '1
AHOCLOI 124* (N)
C*MMMMoni lOOppn In MCH
III* 11/22 EX. & 22/11 IM.
Tim* Confront C i i«r
l.coroV 0 0| (^
Gain 330, 1000/10, 410, 1000/4.4JJ, 100/44
Temperature T^K
Emiuion Wav>lvi9th 330,410,455
Excitation //aveltngth 283 rwn
Gain 100/8.0
600
WAVELENGTH (wmt.,,)
Figure 33. Ejccltation/emiision •p.n,. o» Aroclor 1248
(N. 100 ppm) in MCH at 77- K
700
Excitation Atav»l.no.ih 2o5p«ctr« of Aroclor 1248
(N. 10 ppm) in MCH at 77* K
37
-------
Sf -I
AtOClOt I24B (N)
I ppn inMCH
Slfc 11/33 EX. & 33/11 EM.
MM Contort I.Owe.
ReCOItier 0.01 Mo>
Gain 1000/500
Temperature 77°K.
Emiuion Wavelength472/in
Excitation Wavelength 270n
Gain 1000/300
WAVELENGTH (nonomefcn)
Figure 35. Excitation/emission spectra of Aroclor 1248
(N. 1 ppm) in MCH at ^T K
TDD
Sampl.: AROCLOR 1246 (N)
Coocentra»lon:0.1 ppm in MCH
SUM 11/33 EX. & 33/11 EM.
TimeComtant 0.3wc.
tecocder 0.01 Max
Gain 300/10
Temperature 77° K
Embilon Wavelength 440™.
500
WAVELENGTH (nanometen)
Figure 36. Excitation/emUiion apectra of A roc lor 1248
(N, 0. 1 ppm) in MCH »t IT K
38
-------
SF - 1
SompU: *BGCLC» 1254 (N)
Concentration: IX ppm in MCH
Slin 11/22 EX. & 22/11 EM
Time Constant 0. 1 &«c .
0.01 M>X
Goin Em. 410 100/800. Em 46*
400 500
WAVELENGTH (nanometer^
Fifnr« 37. Excitatian/emitiion spectra of Aroclor 1254
(N. 100 ppm) in MCH at 77- K
600
"i-m^t. AtCK^lCt I2S4 (N)
Concentration: 10 ppm In MCH
Site 1I/22EX. 4 22/11 EM.
1.0 sec.
0.01 Mcu
Goin 1000/10
Icmp^itur. 77°K
.,4IOnm.
WAVELENGTH (nenan*r«n)
Figure 38. Exc itation/emi»»ioo cpectrm of Aroclor 12S4
(N, 10 ppml i» MCH at 77- K
39
-------
ln.tnjm.nt SF -I
Somfrfe, ARCXLOR I260(N)
Concentration, lOOpom In MCH
Slllt 11/22 EX. & 22/11 EM.
Tim* Content 0.1 uc.
•.•corder 0.01 Max
Gain 100/950
Temperature 77°K
Embilon Wavelength 4IO,440nm
Excitation Wavelength
Gain 100/900
«XJ 500
WAVELENGTH (nanom.ten)
Figure 39. Excitation/emission spectra of Aroclor 1260
(N. I 00 ppm) in MCH at IT K
Initiuniwit SF -I
SampU: AROCLOR I2AO (N)
Concmtratlon: lOppm in MCH
Sllh 22/11
Tim* Coratant l.0i»e.
R.corder 0.01 Max
Gain 1000/100
T0mp«mtur« 77°K
Emiulan Wavelength 410, 440nrr
Excitation Wavelength 29/nm
Gain 1000/680
SCO
WAVELENGTH (nanometers)
Figure 40. Excitation/emission apectra of Aroclor 1260
(N, 10 ppm) In MCH at IT K
40
-------
Instrument SF -
Sompl.: AROCLC8 1260 fNj
Concentration: loom in MCH
Sllh li/33 EX. & 33/11 EM.
Tim* Constant 1 .0 vec.
Recorder 0.01 Ma,
Gain l«Xy9SO
Temperature 7/ If
Emission //ovelength
Licltatlon ,Vav«l«ngth 292nm
Gain 1000/SOO
400 500
WAVELENGTH (nonomet.n)
Figure 41. Excitation/emission spectra of Aroclor 1260
'N, 1 ppml in MCH it IT K
AlOCLO* 1260 (N) & MCH
Ml*., 0. r ppm in MCH
SltH II 33 C*. 4 33/11 EM.
WAVELENGTH (nanam«t
-------
concentration decreases, energy transfer processes become less
probable, and the excitation structure appears to shift to shorter
wavelengths. Since the observed excitation changes are probably a
complex combination of both geometric and energy transfer effects, it
would appear that in an analytical method these effects would have to be
determined empirically for a given Aroclor.
Degassing experiments performed on 10 ppm solutions of Aroclor 1254
in MCH using the technique described previously (SECTION V) showed
that the Aroclor phosphorescence intensity remained unaffected within
lO^o. Again, however, we must emphasize that the method used for
oxygen removal may not be highly efficient, a vacuum system being
preferred for this operation.
In the fifth monthly report it was stated that an impurity emission
associated with Aroclor 1254 appears at Aroclor concentrations less
than about 1 ppm. The structured emission consists of fluorescence
in the 300 - 370 nm region (maximum at approximately 310nm) and
phosphorescence in the region 400- SOOnm. The phosphorescence and
fluorescence systems appear to be associated with separate emitting
species. More recently, these emissions have been observed in non-
Aroclor samples as well. We presently believe that the source of these
emissions are in fact from plasticizers used in the polyethylene stoppers
for our sample containers.
Photolysis of Aroclor 1254
Preliminary photolysis experiments were performed on Aroclor 1254
both in MCH and ethanol at 77° K and at room temperature. The methods
employed were simple, but were probably adequate to reveal gross
effects. The sample was irradiated while in the quartz optical dewar
at its normal position in the Baird-Atomic SF-1 Fluorispec instrument,
using the standard instrument source (SECTION IV). Excitation slits
were at their full width (spectral band pass about 24nm) and the excita-
tion monochromator set at 285nm.
Irradiation for two hours with the sample at 77° K in either solvent
produced no significant spectral changes. (Since the average data-
acquisition time on our instruments rarely exceeds 15 minutes, it
seems unlikely that normal low-temperature measurements could
induce serious photochemical changes in the Aroclor. )
Room-temperature irradiation was done in the same manner for periods
of 15-18 hours. In MCH, some photochemical changes were observed,
but these were found to be much more pronounced in ethanol, wherein
42
-------
additional structure appeared in the Aroclor phosphorescence system.
This new structure bore a resemblance to the phosphorescence spectra
of some of the lower-chlorinated biphenyl isomers as discussed prev-
iously (SECTION VI). In particular, the principal peaks of this
system were found to agree rather well both in energy and relative
intensity with those appearing in the phosphorescence spectrum of
4, 4'-dichlorobiphenyl; spectra of the photolyzed Aroclor are compared
with those of this isomer (in ethanol) in Figure 43.
SAMPLE: 4.4'-Ci-Hph«i,l i pho>t>l,i«i AtOCLOU
1254.
CONCENTRATION I00pp» In E*hc»of
SLITS 11/22 Ex. & 22/11 En..
TIME CONSTANT O.I i«c.
KECOtDER 0.01 MAX
TEMPttATLRE
GAIN 100/3.0 a 12544 10/8.64 a 4.4'
EXCITATION WAVELENGTH 2BOnm.
EMISSION WAVELENGTH 480m...
GAIN 100/3.00112541 100/10.0 a 4.4-ClSi(*.«.r<
Figure 43. Excitation/emission spectra of 4, 4'-dichlorobiphenyl
(100 ppm) photolyzed Aroclor 1254 (originally 100 ppm)
in ethanol at 77° K
Although this identification is only tentative, it is interesting to note in
this connection some recent photochemical studies of toxic chlorinated
dibenzo-p-dioxins.21 Photolysis of these compounds in alcoholic media
apparently results in homologs of diminished chlorine content, suggest-
ing reductive dechlorination as a primary mechanism.
Similar photochemical effects in PCB isomers and mixtures have very
recently been reported by Hutzinger and Safe.22 Sample irradiation
was performed in the vapor phase, in aqueous suspension, in thin films
of pure material, and in hexane, methanol, and aqueous dioxane solutions
43
-------
In all experiments, large amounts of dechlorinated compounds were
found among the decomposition products. In addition, new "polar"
compounds, which probably included hydroxychlorobiphenyls, were
formed when air and water were present during photolysis. The authors
suggest that the hydroxy compounds may act as intermediates in the
formation of toxic chlorinated dibenzofurans.
Determination of Aroclor 1254 in Water
Several experiments, in order of increasing technical difficulty, were
performed relating to the determination of Aroclor 1254 in water.
Water saturated with this Aroclor was examined at room temperature
in a 1 cm path cuvette. Excitation at wavelengths known to produce
emission at 77° K in organic solvents revealed no clear evidence of
Aroclor fluorescence (phosphorescence is not observed at room tem-
perature). This is probably a consequence of both the low Aroclor solu-
bility in water (.3-1 mg/12^ or perhaps less^) and the low fluores-
cence yields found for more highly chlorinated PCB isomers.
In order to enhance the solubility of the Aroclor in water and allow
examination at low temperatures, ethylene glycol was added to an
Aroclor 1254/water sample in the ratio two parts ethylene glycol to one
part water, and the solution examined at 77° K. Aroclor phosphores-
cence was not apparent in this sample, but was probably obscured by
emitting impurities present in the ethylene glycol. An attempt to sub-
stitute ethanol for ethylene glycol proved unsuccessful for the same
reason. These experiments were therefore inconclusive and should be
repeated with solvents of higher purity. If successful, this method
would be important in that possible extraction steps might be elim-
inated.
Finally, Aroclor 1254 was extracted from water with methylcyclohexane.
The organic layer was dried with sodium sulfate^ and examined at 77° K.
Aroclor phosphorescence was observed, and comparison of the intensity
with that of a 1 ppm standard solution indicated an Aroclor solubility in
water of approximately 0. 01 mg/1. This value must be regarded as
tentative, since a UV absorption of the same extract showed differences
presumably due to altered isomer composition.
44
-------
SECTION VII
ANALYSIS OF MIXTURES: AROCLOR 1254 AND p, p' -DDT
Standard Low Temperature Measurements
The phosphorescence of Aroclor 1254 is approximately 10X stronger
than that of DDT in MCH at 77° K. Detection limits (also in MCH at
77° K) for the DDT/DDD compounds and for Aroclors are presently
limited by solvent impurity emission and are on the order of 1 ppm
and . 01 ppm respectively. These limits could be reduced by two
orders of magnitude by suitable solvent purification and such experi-
ments are planned for the continuation program.
Excitation and emission spectra of three mixtures containing 50 ppm
p,p'-DDT (all samples) and 50, 5, and 0. 5 ppm Aroclor 1254 are
shown in Figures 44 - 46. The solvent used was MCH glass at 77° K.
Since DDT has virtually no absorption at wavelengths greater than
280nm, excitation of the mixture in the 290nm region allows the
Aroclor phosphorescence to be observed relatively free of DDT emis-
sion. Also, since the Aroclor phosphorescence at 380nm is negligible,
an excitation spectrum monitored in this region produces largely the
spectrum of DDT with little interference from Aroclor. Energy-
transfer processes are probably not strongly operative in this system
since the DDT phosphorescence spectrum is always evident.
Similar results were obtained in mixtures of 5 ppm p,p'-DDT with 5,
0. 5, and 0. 05 ppm Aroclor 1254. In these mixtures the Aroclor phos-
phorescence is clearly visible as shown in Figures 47 through 49-
These results imply that at the concentrations used, Aroclor 1254 can
be observed in the presence of at least 100X higher levels of p,p" -DDT.
Similar results are expected at lower absolute concentrations.
Of interest too is that 5 and 50 ppm DDT can be detected in the
presence of an equal amount of Aroclor. This suggests that it may be
possible to detect smaller quantities of DDT-type pesticides in the
presence of larger quantities of Aroclors; this determination would of
course be less sensitive than the reverse situation due to the smaller
phosphorescence yields of the pesticides.
Results similar to those obtained for the above Aroclor/DDT mixtures
are expected to obtain for other Aroclors and pesticides, provided the
45
-------
:' SAMPLE: p,p'-ODT 4 AROCLOR 1254
CONCENTRATION 50 ppm p,p'-DDT
4 SOppm AROCLOR 1254 In MCH.
SLITS 11/22 Ex. 4 22/11 Em.
TIME CONSTANT O.I IK.
RECORDER 0.01 MAX
TEMPERATURE 77°K.
GAIN 100/10 at 240nm & 10/10 at 290nm.
EXCITATION WAVELENGTH 240nm & 290nm.
EMISSION WAVELENGTH 360nm 4 445nm.
GAIN 100/10 at 380nm & 10/10 at 445nm.
vVAVELENCTH(nonom
Figure 44. Excitation/emission spectra of a mixture of p, p'-DDT
(50 ppm) and Aroclor 1254 (50 ppm) in MCH flaai at 77- K
700
SAMFUi p.p'-OOT 4 AROCLOR 1254
CONCENTRATION JOppni p,p'-DDT
t Jppn AROCLOR 1254 In MCH.
11/22 Ex. 4 22/11 Em.
TIME CONSTANT O.I IK.
DKOKOER 0.01 MAX
TEMPttATURE 77°K
GAIN 100/9
EXCITATION WAVELENGTH 240nm
t 290nm.
EMISSION WAVELENGTH 380nm
t 445nm.
GAIN MOnm at 100/10 4 445nm
ol 100/5.
LLJ
Z
200
Excitation/emiiiion ipectra of a mixture of p,p' -DDT
(SO ppm) and Aroclor 1Z54 (5 ppm) in MCH gla» at 77* K
46
-------
SAMPLE: p.p'-ODT & AHOCLOt I2S4
CONCENTRATION JOpsm p,p'- DDT
80-5 opm AROCLOR I2S4 In MCH.
SLITS 11/22 Ex. & 22/11 Em.
TIME CONSTANT O.I IK.
RECORDER 0.01 MAX
TEMPERATURE 77°K
GAIN 300/9
EXCITATION WAVELENGTH Z40w*
4 290nm.
EMISSION WAVELENGTH 400™»
& 4X5rm.
GAIN 100/V
WAVELENGTH(nonometen)
Figure 46. Excitation/emieeion spectra of a mixture of p. p1 -DOT
(50 ppm) and Aroclor 1254 (0. S ppm) in MCH |1... at IT K
IBAIHO-AIDMB!
Instrument SF - 1
Sample: p p1- DDT 4 AROCLOR 1254
Concentration: 5.0ppm p,p'-DDT and
3 0 pen AROCLOR IN MCH
Slltl 11/13 at 380 nm, 11/22 at 450 nm
and 13/11 ot 244 nm, 22/11 at 290 nm
Time Canitanl 0. I lee .
Recorder 0.01 Ma*
Gain 100/6.13 ot 380 4 1000/6.36 ot 450 nm.
Temperature 77°K
Em In Ion Wavelength 380 , 450 nm.
Excitation Wavelength 244, 290 nm.
Gain IOO/V.2Sal 244, 100/2.60 at 290 nm.
WAVELENGTH ( nanome*en )
Figure 47. Excitation/emieeion spectra of a mlature of p. p' -DDT
(5 ppm) and Aroclor 1254 (5 ppm) IB MCH |Uee at 11' K
47
-------
Sanpltt p.p>- DDT ft AKOCLOR 1254 (N)
Cancent«tlon.5.0ap». p.p'-DDTiO.SppmAROCLCR In MCH
Silk 11/22 EX. & 22/11 EM.
Tim* Comtont 1.0 MC.
lecoraer 0.01 Max
Gain 1000/10
Temporatura 77°*.
Emiuion Wav«leog»h 385, 450nm.
Excitation Wavelength?**. 290™.
Cain 1000/10
WAVELENGTH (nanameten)
Figure 48. ExeibUioB/emi>eioa epectra of a mixture of p. p- -DDT
(5 ppm) u4 Aroclor 1254 (N, 0. 5 ppm) in MCH |lue
at 77-K
Sonifl*: p,p'-OOT & AHOCLOt 1254 (N)
Concentration* ppnp.p'-DDT&O.OS pan AHOCLCC
Slis 11/33 EX. & 3VM EM.
o.i
0.01 MAX
1000/8.4
77°K
Emhiion Wavelength 380
in MCH
Excitation Wavelength 275, 293 nm
Gain 1000/6.0 at 275 & 1000/7.10 at 296
WAVELENGTH (nanameten)
Figure 49. Excit»tioa/«
-------
pesticide were either DDT or ODD. The very weak emission observed
for DDE (SECTION V) makes it difficult to determine with high sensi-
tivity by molecular emission methods. On the other hand, DDE should
produce little if any interference for PCB' s with which it might occur.
Further, PCB' s do not interfere with analysis of DDE in gas chromato-
graphic analyses. ^5
Phosphor oscopic Measurements
Exploratory phosphoroscopic and polarization measurements were
performed on a mixture of Aroclor 1254 (5 ppm) and p,p'-DDT (50 ppm)
in MCH at 77° K in order to determine whether they could provide addi-
tional discrimination in the analysis of Aroclor/pesticide mixtures.
The phosphoroscopic method could be of value in separating phosphores-
cence emissions which are spectrally overlapping but differ in their
respective lifetimes. The phosphoroscope, a standard accessory on
the Fluorispec, was a rotating -can type which could be operated at
continuously variable speed. A good general discussion of this and
other types of phosphoroscopes can be found in Reference 9- In this
type of experiment, the component having the longer phosphorescence
lifetime can be selectively enhanced by operating the phosphoroscope
at minimum speed. For the mixture chosen, the enhancement thus
obtained was low, presumably due to the similar lifetimes of the com-
ponents. Aroclors having low chlorine content (e. g. , Aroclors 1221,
1232) and thus longer phosphorescence lifetimes are expected to show
greater selective intensification using this method.
Photoselection (Polarization) Measurements
Polarize"?! excitation spectra are obtained in a viscous or rigid medium
by exciting the sample with vertically polarized light and monitoring
the vertically and horizontally polarized components of the emission.
The results of such an experiment are usually expressed by the degree
of polarization P as given by the equation
*VV~GIVH
=
represents the emission intensity when both polarizer and analyzer
are oriented to pass only vertically polarized light, i. e. , light polar-
ized with electric vector normal to the plane containing the excitation
and observation beam. Similarly, IVH represents the intensity for
vertical orientation of the polarizer and horizontal orientation of the
49
-------
analyzer. G is an instrumental correction factor whose determination
is discussed in detail by Azumi and
The polarization spectrum would ordinarily consist of a plot of P vs
excitation wavelength. Theoretically, the value of P can range from
+ . 50 to — . 33, but these limits are seldom observed experimentally.
Wavelength regions having positive values of P indicate that the transi-
tion moments responsible for absorption and emission of light are
parallel. Conversely, negative values of P result when these moments
are orthogonal. Thus, the polarization spectrum gives valuable in-
formation on the relative orientation of molecular transition moments.
A general discussion of photoselection methods, with recent references,
is given in Reference 9-
Polarized excitation spectra were obtained for a mixture of Aroclor
1254 (5 ppm) and p,p'-DDT (50 ppm) in MCH glass at 77° K. Plots of
P versus wavelength have not as yet been made due to a possible inac-
curacy in the value of the correction factor G. Nevertheless, we have
decided to include the unreduced data, namely lyy and lyj^ in this
report for purposes of illustration. These spectra appear in Figure 50.
Sonpl* p. p'-ODT 4 AIOCLC* 1254
Counrnition: 50pf«n p, p'-DDT S O.Sppm ABOCIO* in MCH
Slit, 11/33
Tim* Comtont 0.3MC.
0.01 MAX
Coin 30/10 at 380, 30/2 01 470, 30/S 5 al 500 rm.
T«mp*rotvr« 77 K
Extebn Wa».l«ngtti 380, 470, 500 ~n.
lyy and lyH r«f*»Mnt inrv»ltl«i obtained
irti wcltation polariuf v%itlcol,«wlxzlng po^ariur
'loot ondhorllDfltal, l«p«cllv«ly.
Figure 50. Polarized excitation spectra of a mixture of Aroclor 1254
(5 ppm) and p, p' -DDT (50 ppm) in MCH glass at 77° K
50
-------
Spectra obtained by monitoring 380, 470, and 500nm emission contain
increasingly larger proportions of Aroclor emission; the 380 nm
spectrum is in fact predominantly that of DDT. Clearly, the degree
of polarization becomes much less positive (lyv — ^VH^ as tne
excitation spectrum is monitored at successively longer wavelengths,
indicating that the values of P for the Aroclor differ significantly from
those of DDT. It should be noted that the sharp origin band of p, p1 -
DDT found at 277 nm in the unpolarized spectra (Figures 4 and 8) was
not observed in the polarization spectrum monitored at 380 nm, and
we are unable to account for this at the present time. The results
reported here are very preliminary and future work must include
comprehensive studies on the polarization behavior of the individual
components. However, the preliminary results suggest that polariza-
tion methods may be of value in enhancing contrast between Aroclors
and pesticides.
51
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SECTION VIII
SUMMARY
The purpose of this study was to examine the applicability of low
temperature luminescence as a means of detecting polychlorinated
biphenyls {PCB1 s) in the presence of DDT and related pesticides.
Basic studies completed during the six month contract period have
thus focused upon the documentation of important pesticide and PCB
spectra, including various mixtures of these.
PCB Isomers and Mixtures (Aroclors)
Excitation and emission spectra have been obtained for seven PCB
isomers at low temperatures. Most measurements were done using
methylcyclohexane (MCH) solvent, which forms a clear rigid glass at
77° K. Phosphorescence in these compounds (PCB isomers) is more
intense than fluorescence, and increased chlorine substitution increases
the relative yield of phosphorescence to fluorescence. Some of the
lower-chlorinated isomers exhibit quasilinear spectra in heptane
matrix at low temperature; a similar sharpening is observed in the
emission spectra of Aroclor 1221 in heptane, reflecting the low chlorine
content of the isomer components. Spectra of isomers and Aroclors
having relatively high chlorine content are not significantly sharpened
in a heptane matrix. This may be a result of intrinsic broadness, or
may indicate that aliphatic hydrocarbon solvents having greater chain
length (e. g. , octane, nonane) are more appropriate Shpolskii matrices.
It should be noted, however, that spectra of 2,5,2', 51 -tetrachloro-
biphenyl in octane and nonane at 77° K showed no evidence of additional
sharpening, so that for this isomer, at least, the diffuseness of the
phosphorescence is probably intrinsic.
Even in solvents producing relatively broad spectra, spectral differences
are sufficient to allow the five Aroclors we have studied (1221, 1242,
1248, 1254, and 1260) to be differentiated. Further work along these
directions would include a greater number of important PCB isomers
(which had been previously identified in Aroclor mixtures) in order to
further define sources of luminescence in Aroclors.
Photochemical changes have been noted in Aroclor 1254, and these
studies should be extended to other Aroclors and pesticides to deter-
mine whefiier analytical methods could be based upon prior photolysis.
Additional PCB isomer spectral data might prove helpful in this context
since the photoproducts include other isomers.22
53
-------
Pesticides
The excitation and emission spectra of the four DDT and DDD compounds
are all very similar. It may be possible to distinguish between these
by differences in phosphorescence lifetime or polarization. Observed
emission from DDE isomers was very much weaker than for the DDD
or DDT compounds. Further experiments are needed to determine
whether the observed emission is due to DDE itself or to an impurity.
The low emission yield of DDE makes it more difficult to determine
with sensitivity, but also reduces its interference with PCB measure-
ments. Further, PCB's do not interfere significantly with the GC
determination of p, p1 -DDE."
Aroclor/Pesticide Mixtures
Mixtures of Aroclor 1254 and p, p'-DDT were studied in MCH at 77° K.
Aroclor concentrations ranged from . 05 to 50 ppm with DDT concentra-
tions of 5 and 50 ppm. It was found that Aroclor could be detected in
the presence of DDT levels at least 100X greater. Conversely, DDT
could be detected in the same mixtures in the presence of equal (or
lower) levels of Aroclor. Lower concentrations of the components
could have been realized. The current practical limit is due to emis-
sion from solvent impurities which limit detection sensitivities to
approximately 1 ppm and . 01 ppm for DDT/DDD and Aroclor respec-
tively. Better solvent purity is therefore essential. Much additional
work is needed in this area to establish linear ranges of detectability
and also detection limits.
Polarization and phosphoroscopic methods were applied to a mixture
of Aroclor 1254 (5 ppm) and p, p' -DDT (50 ppm) in MCH at 77° K in
order to enhance, if possible, contrast between these components.
The phosphoroscopic method, which exploits differences in phosphor-
escence lifetimes, did not result in much additional contrast for the
mixture chosen, presumably because of similarities in lifetimes.
Better contrast should be obtained with Aroclors of lower chlorine
content (e. g. , 1221, 1232) and thus longer phosphorescent lifetimes.
In the polarization method (also known as photoselection) an excitation
spectrum is obtained by monitoring horizontally- and vertically-
polarized components of emission produced by excitation with polarized
light. This method revealed differences in polarization between
Aroclor and DDT which might be used to enhance contrast. The
experimental results are very preliminary, however, and require
much further study.
54
-------
In conclusion, the basic studies conducted during the initial contract
period, while not complete, are very encouraging and clearly demon-
strate the applicability of low temperature luminescence to the deter-
mination of PCB1 s in the presence of DDT-type compounds.
55
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SECTION IX
ACKNOWLEDGMENTS
We gratefully acknowledge the support and direction of Mr. D.
Ballinger of the EPA Analytical Water Control Laboratory, Cincinnati,
Ohio.
Sincere thanks are due to Dr. R. G. Webb of the Athens, Georgia,
EPA Laboratory, and Dr. O. Hutzinger of the National Research
Council of Canada, Halifax, Nova Scotia for providing samples of
PBC Isomers. We are also indebted to Dr. E. S. Tucker of the
Monsanto Company for providing us •with additional Aroclor samples.
The special contribution of Miss Judith Guilfoyle to the early phases
of the project is gratefully acknowledged. Finally, thanks are due
Mrs. Geraldine Garnickfor considerable assistance with the laboratory
studies.
57
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SECTION X
REFERENCES
1. J. Armour and J. Burke, " Polychlorinated Biphenyls as Potential
Interference in Pesticide Residue Analysis," FWPCA Laboratory
Information Bulletin No. 918, July 1, 1969.
2. "FWPGA Methods for Chlorinated Hydrocarbon Pesticides in
Water and Wastewater, " U. S. Department of the Interior, Federal
Water Pollution Control Administration, April, 1969.
3. L. M. Reynolds, Residue Reviews, 34, 27 (1971).
4. J. Pichirallo, Science, 173, 899 (1971).,
5. T. W. Duke, J. I. Lowe, and A. J. Wilson, Jr. , Bull. Envir.
Contam. and Toxicol. , j>, 171 (1970).
6. V. Zitko and P. M. K. Choi, Fisheries Research Board of Canada,
Technical Report No. 272, 1971.
7. R. W. Risebrough in Impingement of Man on the Oceans,
D. W. Hood, Ed., Wiley-Interscience, New York, 1971.
8. H. Hays and R. W. Risebrough, Natural History, 80, 39(1971).
9. J. D. Winefordner, P. A. St. John and W. J. McCarthy in
Fluorescence Assay in Biology and Medicine, Vol. II, by
S. Udenfriend, Academic Press, New York and London, 1969,
pp. 85-89.
10. Beat Meyer, Low Temperature Spectroscopy, American Elsevier
Publishing Co. , Inc., New York, 1971, pp. 203-205.
11. H. A. Moye and J. D. Winefordner, J. Agr. Food Chem. , 13,
516 (1965).
12. L B. Berlman, Handbook of Fluorescence Spectra of Aromatic
Molecules, Academic Press, New York and London, 1965, p. 88.
13. R. A. Webb and A. C. McCall, " Identities of Polychlorinated
Biphenyl (PCB) Isomers in Aroclors, " presented at the 162nd
National Meeting of the American Chemical Society, Washington,
D. C. , 13 September 1971.
59
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14. D. Sissons and D. Welti, J. Chromatogr. 60, 15 (1971).
15. A. C. Tas and R, H. deVos, Environmental Science and Technology,
_5, 1213 (1971).
16. O. Hutzinger, S. Safe, and V. Zitko, Bull. Environ, and Toxicol. ,
.6, 209 (1971).
17. E. V. Shpolskii, Soviet Phys. Usp. , _3» 372 (I960); S_, 522 (1962);
6, 411 (1963).
18. D. S. McClure, J. Chem. Phys., 17, 905 (1949).
19. M. Bixon and J. Jortner, J. Chem. Phys., 48, 715(1968).
20. J. Petruska, J. Chem. Phys., 34, 1111 (1961).
21. D. G. Crosby, A. S. Wong, J. R. Plimmer, and E. A. Woolson,
Science, 173, 748 (1971).
22. O. Hutzinger and S. Safe, "Photochemical Behavior of Chloro-
biphenyls (PCB)" .presented at the NIH Conference on Poly-
chlorinated Biphenyls, Quail Roost Conference Center, Durham,
N. C. , 20 December 1971.
23. V. Zitko, Fisheries Research Board of Canada, Manuscript
Report Series No. 1038 (1970).
24. R. G. Webb and A. C. McCall, unpublished results.
25. R. W. Risebrough, P. Reiche, and H. S. Olcott, Bull. Environ.
Contam. and Toxicol. , 4, 192 (1969).
26. T. Azumi and S. P. McGlynn, J. Chem. Phys., 37, 2413 (1962).
60
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SECTION XI
APPENDIX
When dilute solutions of organic molecules in n-alkane matrices are
analyzed at low temperatures, it is often found that the absorption and
emission spectra become quite narrow, often resembling atomic lines.
A review of this "quasilinear" structure has been given by Shpolskii,1
who pioneered in this important field.
Usually, it is found that the sharpest spectra are obtained in those
n-alkane matrices whose molecular dimensions are nearly the same as
those of the solute molecule. Single vibronic bands of the free mole-
cule usually appear as multiplets in the alkane matrix. The energy
separation between multiplets is usually the same for all vibronic
bands and is probably due to guest substitution in several different
crystalline phases of the host. Additional multiplets may arise from
energetically different sites within a particular phase.
Bandwidths are strongly temperature dependent, becoming broader as
the temperature is raised. Kizel and Sapozhnikov,2 for example, have
found that the origin band of 3, 4-benzopyrene varies in half widths from
about 5 cm""1 at 77° K to 140 cm.—1 at 140° K, and attribute this broaden-
ing to a redistribution of intensity into photon (lattice) vibrational modes.
Diffuse spectra may accompany the quasilinear structure. Grebenshchikov
and Personov measured the temperature dependence of the triplet
lifetimes and intensities of several molecules, including biphenyl, in
various n-alkane matrices from 77° K to the melting point. Oxygen
quenching of the phosphorescence was observed above 90° K, but not at
77° K. Biphenyl was found to possess quasilinear structure in heptane,
but in decane this structure became much more diffuse. The diffuse
system in decane was found to be much more sensitive to oxygen
quenching upon warming than was the quasilinear heptane system. The
authors thus attributed the sharp system to well-separated guest mole-
cules distributed substitutionally in the alkane matrix and the broad
system to molecules adsorbed on the surfaces of microcrystals of the
host. Grebenshchikov, et al.^ also reached the conclusion of two differ-
ent emitting moieties (one having sharp spectra and the other diffuse) in
their studies of luminescence bandwidths of several organic molecules
in n-alkane matrices having from 6 to 12 carbon atoms. Finally,
Bolotnikova and Gurov5 found both broad and narrow emission in a
10~3 M solution of anthracene in heptane at 77° K. The broad emission
was strongest at the surface of the sample, whereas the sha.rp emission
was strongest in the central region of the sample. The authors concluded
61
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that the broad emission was due to the molecular aggregates of
anthracene excluded during crystallization. This result suggests that
quasilinear spectra should be more favorable at low solute concentra-
tions. In an earlier study, however, Bolotnikova and Naumova" found
that spectra of naphthalene in heptane at concentrations ranging from
1 0~5 to 10~1 M became sharper as the naphthalene concentration was
increased, the quasilinear structure appearing at 10~~^ M. Similarly,
the phosphorescence of phenanthrene in n-octane became increasingly
sharp at concentrations above 1 0~3 M. In n-hexane however, the
phenanthrene phosphorescence was found to be quasilinear, independent
of concentration. No reference was made to these apparent anomalies
in later work {Bolotnikova and Gurov^).
In summary, it is usually found that quasilinear spectra are obtained
in n-alkane matrices whose molecules have dimensions similar to that
of the guest. For example, naphthalene and anthracene should have
sharpest spectra in pentane and heptane, respectively. Invariably,
spectra become sharper as the temperature is decreased and usually
temperatures of 77° K or lower are preferable. Variables such as
rate of crystallization and concentration as these affect bandwidths are
less well understood at present, and it would appear advisable to deter-
mine the nature of these effects empirically for given combinations of
solute and solvent.
1. E. V. Shpolskii, Sov. Phys. Usp. , 3, 372 (1960); j[, 522 (1962);
_6, 411 (1963).
2. V. A. Kizel and M. N. Sapozhnikov, Phys. Stat. Sol. , 41, 207
(1970).
3. D. M. Grebe/ishchikov and R. I. Personov, Opt. Spectrosc. , 26,
142 (1969).
4. D. M. Grebenshchikov, N. A. Kovrizhnykh, and R. I. Personov,
Opt. Spectrosc., 30, 32 (1971).
5. T. N. Bolotnikova and F. I. Gurov, Opt. Spectrosc., 28, 94
(1970).
6. T. N. Bolotnikova and T. M. Naumova, Opt. Spectrosc. , 25,
253 (1968).
62
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
/. Report No.
3. Accession No.
w
4. Title
IDENTIFICATION OF POLYCHLORINATED BIPHENYLS
IN THE PRESENCE OF DDT-TYPE COMPOUNDS,
7. Author(s)
Brownrigg, J. T. , Eastwood, D., and Hornig, A. W.
9. . Organization
Baird-Atomic, Incorporated
Bedford, Massachusetts
5. Report Date
6.
8. Performing Organization
Report No.
10. Project No.
16020 GIY
12. Sponsoring Organization
15. Supplementary Notes
11. Contract/ Grant No.
68-01-0082
/3. Type ol Report and
Period Covered
fiivironmental Protection Agency report
number EPA-R2-72-OC&, October 1972..
16. Abstract Polychlorinated biphenyls (PCB's) interfere with gas chromatographic
analyses of DDT and related compounds, necessitating a simple independent method for
PCB determination. The purpose of the present study was to determine the applica-
bility of low temperature (77° K) luminescence methods to this problem. Basic studies
included documentation of excitation/emission spectra of 6 pesticides (p, p* - and o, p1 -
DDE, DDD, and DDT), 7 PCB isomers, and 5 PCB mixtures (Aroclors). Although
phosphorescence spectra of the DDD and DDT compounds are very similar, possible
differences in lifetime and polarization measurements may aid in differentiation.
Emission from DDE is at least 100X less intense than that of DDD or DDT, and is
therefore more difficult to determine with adequate sensitivity. Spectral differences
among various Aroclors are sufficient to allow those studied to be differentiated.
Emission from solvent impurities presently limit detection sensitivities to about
1. 0 ppm for DDT/DDD and about . 01 ppm for Aroclors. By removing interference,
detection sensitivities should be improved by two orders of magnitude.
Low temperature luminescence studies in various binary mixtures of Aroclor 1254
and p, p'-DDT indicate Aroclor 1254 may be identified and quantitated in the presence
i of DDT concentrations 100X greater.
17 a. Descriptors
* Analytical techniques, *Chemical analysis, * Fluorescence, *Chlorinated hydro-
carbon pesticides, *DDT, Spectroscopy, Spectrophotometry, Organic compounds,
Aromatic compounds, Pesticides, Organic pesticides.
17b. Identifiers
* Polychlorinated biphenyls, * Aroclors, * Low temperature luminescence,
Luminescence.
llc.COWRR Field & Group 05A, 07B
18. Availability
19. Security Class.
(Report)
20. Security Class.
(P»te)
21. No. of
Pages
Send To:
Abstractor
22. Price
\ Institution
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C 20Z4O
WRSICI02(REV JUNE l»71>
» U. 3. GOVERNMENT PRINTING OFFICE : 1972— 514-148/65
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