United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/540/R-94/519
October 1994
EPA
A Field Screening
Method for
Polychlorinated Biphenyl
Compounds in Water
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EPA/540/R-94/519
October 1994
A FIELD SCREENING METHOD FOR
POLYCHLORINATED BIPHENYL
COMPOUNDS IN WATER
by
Shen Lin and Edward J. Poziomek
Harry Reid Center for Environmental Studies
University of Nevada-Las Vegas
Las Vegas, NV 89154-4009
Cooperative Agreement No. CR818353
Project Officer
William H. Engelmann
Analytical Sciences Division
Environmental Monitoring Systems Laboratory
Las Vegas, NV 89193-3478
ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NV 89193-3478
Printed on Recycled Paper
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NOTICE
The U.S. Environmental Protection Agency (EPA), through its Office of Research and
Development (ORD), partially funded and managed the extramural research described here. It has been
peer reviewed by the Agency and approved as an EPA publication. Mention of trade names or commer-
cial products does not constitute endorsement or recommendation for .use.
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ABSTRACT
The U.S. Environmental Protection Agency (EPA) is continuing in the pursuit of innovative meth-
ods of detection of polychlorinated biphenyls (PCBs) in the environment. The objective of this study was
to develop a simple, inexpensive, and rapid procedure for determination of PCBs in water. Based on pre-
vious testing of real-world samples by General Electric Corporate Research and Development, a co-spon-
sor of this project, there was a special interest in developing a field-screening procedure of PCB aqueous
extracts performed from a current soil remediation procedure in which the extractant contained 1 -3% sur-
factant by weight to enhance solubility of PCBs. A test was therefore developed based on forming com-
plexes of PCBs with Ag+ followed by UV irradiation to form Ag metal. The appearance of color (gray to
brown depending on the PCB concentration) was used to signal the presence of PCB. This method allows
the test color to be directly compared with standard color charts to estimate the PCB concentration level
without the need for instrumentation. In addition to soil remediation monitoring, potential applications
include well monitoring, wellhead protection monitoring, post-closure monitoring, and rapid laboratory
screening. For applications related to soil remediation, it was found that filter papers or SPE membranes
could be used in a dipstick mode by spraying with methanolie AgNCvj and irradiation with 254 nm light
from a hand portable UV light. The detection range was 1.0-500 ppm (or higher) in the presence of 3%
Renex KB or Neodol (R) 1-7 surfactants which are currently being used for PCB soil remediation.
HI
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Contents
Page
Abstract Hi
Figures v
Tables vi
1. Introduction 1
Overview :.. .1
Silver Ion Chemistry .2
PCB Photodegradation .2
2. Objectives 3
3. Field Screening Methods For PCBs 4
4. Approach 5
Overall Strategy 5
Choice of the PCB Sample Collection Technique .5
Choice of Visualization Reagents 6
Design of Experiments 6
5 Experimental 8
Reagents and Materials 8
Equipment • 8
Test Procedures 9
Fluorescence Measurements r 9
6 Results and Discussion 10
Use of Solid Phase Extraction (SPE) Membranes 10
Examples of Findings Using Filter Papers .10
Effect of Interferences 10
Effect of Matrix 13
Effect of Surfactant 14
Reaction Mechanism 14
Effect of Light Wavelength 17
Effect of Titanium Dioxide 17
Results with Samples from Soil Remediation .. 17
Blind Sample Test 18
Fluorescence Measurements 18
Implications for Field Screening 18
7 Summary and Conclusions .21
Bibliography 23
iv
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Figures
Number
Page
1
2
3
4
5
6
7
Photodegradation of 2,2'l4)4',6>6'-Hexachlorobiphenyl .-.-...
An Approach in the Development of a Field Screening Method for PCBs in Water
Possible Mechanism of the PCB Visualization ..-........
Solid State Emission Curves of 10 ppm PCB-1232 with 3% Renex KB on Tabs
of S & S 2043A Filter Paper Before and After Adding 0.059 M AgNOs in
Methanol Solution
Approaches for Sample Collection and Subsequent Detection of PCBs in Water
Comparison of Methods for PCBs
An Approach for Sample Collection and Detection
.2
.5
.16
.18
19
.20
20
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Tables
Number
Page
Citations on Using Thin Layer Chromatography and AgNOs-UV Light for the
Detection of PCBs 6
Parameters Utilized in the Design of Experiments for the Development of a
Screening Test for PCBs in Water 7
3 Composition of Surfactants 8
4 Results with PCBs Using SPE Tabs Suspended for 30 Minutes in Test Solutions
Containing 3% Surfactant 11
5 Test Results with PCBs Using Whatman 541 Tabs and 3% Renex KB 11
6 Test Results with PCBs Using Whatman 541 Tabs and 3% Neodol (R) 1-7 11
7 Results of Sensitivity Experiments Using Whatman 541 Tabs and 3% Renex KB 12
8 Results of Sensitivity Experiments Using Whatman 541 Tabs and 3% Neodol (R) 1-7 -.. .12
9 Interference Test Results Using Whatman 541 Tabs and Neodol (R) 1-7 13
10 Test Results with Neat Organochloro Liquids Using Whatman 541 Tabs 13
11 . Test Results with PCB-1232 Using Different Matrices with 3% Neodol (R) 1-7 15
12 Test Results with PCB-1232 Using Whatman 541 Tabs and Different Surfactants (3%) .. 16
13 Test Results with PCB-1232 on Different Matrices with Using a Mixture of 1.5% wt
Triton X-100 (reduced) and 1.5% wt Neodol (R) 1-7 16
14 Results of Blind Sample Test 18
VI
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SECTION!
INTRODUCTION
OVERVIEW
The U.S. Environmental Protection Agency
(EPA) continues to examine methods for detection
of polychlorinated biphenyl (PCB) compounds in
the environment. The research described in this
report relates to a search for new concepts of field
screening methods applicable to hazardous waste
sites with emphasis on in situ ground water moni-
toring. Polychlorinated biphenyls (PCBs) have
been utilized as plasticizers, flame retardants and
components in a variety of formulations such as
paints, inks, waxes, pesticides, water proofing, and
sealers to mention several (1). The largest single
use of PCBs has been as coolants and insulation
fluid in transformers and capacitors. PCBs can
eventually biodegrade in the natural environment.
However, when they are taken up and accumulated
by living organisms, they cause toxicity problems
at low concentrations. PCBs were first discovered
in environmental samples in 1966 (2). Early con-
cerns about the ecological impact of PCBs and
their toxicities were summarized by Fishbein (1).
A co-sponsor of this work was General Electric
Corporate Research and Development. They were
interested in a simple PCB test to follow progress
of soil remediation.
A PCB compound can have any one of 209
structures depending on the number and positions
of the chlorine atoms. The general formula is
C12H10nCln, where n=l-10; Mullin and co-workers
(3) have reported the synthesis and characterization
of each of the 209 PCB congeners. The generic
PCB structure is illustrated below.
Commercial PCB products are mixtures of chlo-
rinated biphenyl compounds. Monsanto's
Arochlor™ PCB products are classified by four-
digit code numbers, e.g., 1260. The first two digits
indicate the type of molecule (i.e., 12 indicates
biphenyl) and the last two digits indicate the
percentage of chlorine in the mixture by weight,
i.e., 60.
PCBs are very stable and inert, have low vapor
pressures, low flammabilities, high heat capacities,
and low electrical conductivities. Most PCBs are
oily liquids. Their colors and, viscosities vary
depending on chlorine content Less chlorinated
congeners are essentially colorless, while the more
chlorinated ones are darker and more viscous. In
general, PCBs with fewer chlorine atoms are more
soluble, more flammable, and less persistent in the
environment (4). PCBs are very resistant to
hydrolysis, chemical oxidation, and heat. Many
descriptions of PCBs and their properties are avail-
able (1,4-9).
Field screening involves the use of rapid, low-
cost test methods to determine whether a com-
pound of interest is present or absent, above or
below a predetermined threshold at a given site, or
at a concentration within a predetermined range of
interest (10). There is a need for rapid, simple,
inexpensive field screening methods for a variety
of semivolatile organic compounds, including
PCBs. Most of the analytical procedures used for
PCB determination are not attractive for field use
because they typically require laborious extrac-
tions, chromatographic separations, and consider-
able training. Descriptions of the current proce-
dures of analysis for PCBs are available (4-6, 9).
Common analytical methods for PCBs involve gas
cinematography (GC) (e.g., EPA method 608 and
NIOSH method 5503) and GC/MS (mass spec-
trometry) (e.g., EPA method 680). A complication
for development of PCB field screening methods is
that the compounds are not very soluble, ranging
from 0.59 to 0.08 ppm for Arochlor™ 1221 to
Arochlor™ 1260, respectively (5). This poses a
problem for lower detection limits.
The approach described in this report involves
using solid-phase extraction (SPE) membranes to
concentrate PCBs from aqueous solution, using fil-
ter papers as dipsticks, or placing drops of the test
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solutions onto the papers. This is followed by visu-
alization directly of the substrates without further
extraction or manipulation. Visualization is
accomplished by spraying the substrates with a sil-
ver nitrate (AgNO3) solution followed by exposure
to ultraviolet (UV) light. The appearance of gray-
to-brown stains relative to controls signals the pres-
ence of PCBs. Potential screening applications
include well monitoring, wellhead protection mon-
itoring, remediation monitoring, post-closure mon-
itoring, and rapid laboratory screening. A specific
application addressed in this report is to test for
PCBs in 1-3% aqueous surfactant solution; such a
method would have direct applications to soil
remediation.
Surfactants are currently being used in soil
remediation processes.
SILVER ION CHEMISTRY
Silver is considered one of the noble metals and
exhibits positive oxidation states of 1, 2, and 3.
The -t-1 state is the most common. The +2 state can
be present as silver oxide, and also in certain com-
plexes. Silver +3 compounds are few in number.
Most silver compounds are insoluble in water.
AgNO3 is one of the few soluble ones. It is color-
less and readily reduced. Many organic compounds
such as alcohol, sugar, starch, etc., react with it to
form finely divided silver. Both light and heat pro-
mote the reduction (11).
The solubility of aromatic hydrocarbons (Ar)
Ag+ + Ar s± AgAr+ C1)
Ag++AgAr+ y± Ag2Ar++ (2)
increases in AgNO3 solutions. Andrews and
Keefer (12) reported that complexes are formed.
In the above equilibria, the aromatic nucleus
acts as an electron donor. In AgAr*, silver ion is
pictured as being bonded to the aromatic nucleus
from a position above the ring and on the six-fold
symmetry axis of the ring. In the case of Ag2Ar^,
it is presumed that the two silver ions are bonded to
opposite sides of the plane of the ring (12-14).
Silver chloride (AgCl) is insoluble in water and
is very stable in the dark. It is sensitive to light,
which causes its decompositions to silver metal
and chlorine:
This reaction is a fundamental one in photogra-
phy. The darkening of a precipitate of silver chlo-
ride when exposed to light is due to the pho-
todegradation reaction. The dark coloration results
from the finely divided silver that is formed (11).
PCB PHOTODEGRADATION
One route of PCB degradation is through photo-
chemical reactions (15-17). Figure 1 shows sever-
al paths of PCB photodegradation reactions under
different conditions (15). In the present study,
complexatiori of the PCBs with silver ion may
increase the PCB susceptibility to photodegrada-
tion, but this was not investigated in any detail.
The mechanism of the visualization reaction uti-
lized in the present research most likely involves
complexatiori of the PCB molecules with silver
ion, dechlorination under the influence of ultravio-
let light giving AgCl, and photodegradation of the
AgCl to silver metal. This will be discussed in
more detail in a later section.
The ultraviolet absorption spectra of PCBs show
major absorption peaks between 240 and 260 nm,
depending on the chlorine substitution (17). The
UV spectra of PCBs have also been recorded by
Brinkman and co-workers (18-19). Femia and co-
workers (20) reported fluorescence excitation and
emission characteristics of several PCB isomers in
a and p-cyclodextrin (CD). The range of emission
peaks was 325-387 nm depending on both excita-
tion wavelength (272-300 nm) and the a or P-CD
reagent. It was found that the positions of the chlo-
rine atom(s) on the rings drastically affected the
fluorescence intensity of a particular PCB isomer.
Complexation into the CD cavity resulted in
increased emission.
AgCl
hv
(3)
Figure 1. Photodegradation of
2,2' ,4,4', 6,6'- Hexachlorobiphenyl.
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SECTION 2
OBJECTIVES
The major objective was to develop a simple,
inexpensive, and rapid procedure that can be used
for screening PCBs in water. The research was
meant to advance the state of the technology in
providing an attractive alternative to existing field
screening methods for PCBs. There is a special
interest based on previous testing in developing a
test for PCBs in the presence of 1-3% by weight of
surfactants. Some soil remediation is currently
using these concentrations of surfactants.
As described in this report, the procedure
involves forming complexes of the PCBs with sil-
ver followed by UV irradiation to form silver
metal. A secondary objective was to exploit the
results by suggesting guidelines for the develop-
ment of new field screening methods for
organohalogen compounds and other pollutants.
The detection limit sought was at 1 ppm.
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SECTIONS
FIELD SCREENING METHODS FOR PCBs
Several field screening techniques for PCBs
already have been described. A technology that
has matured dramatically in the past several years
involves the use of immunoassays, all using differ-
ent formats. An appreciation of the evolution of
the technology can be obtained by reading relevant
papers that have been presented at recent EPA field
screening symposia describing PCB immunoas-
says (21-22).
Another PCB screening approach involves the
use of room temperature phosphorescence (RTP)
(23). The application is for screening soils. While
the detection limit of the RTP tests is low (7.5 ppb
for PCB-1221 to 620 ppb for PCB-1254 (23)), a
substantial amount of manipulation is required;
also, the screening methods developed to date
require sophisticated laboratory instrumentation
and trained operators. For example, a second-
derivative method and synchronous scanning tech-
niques have been proposed to improve RTP screen-
ing of PCBs (24).
There are also field screening techniques based
on chloride ion determination. For example, PCBs
are extracted from a soil sample using an organic
solvent. Sodium is used to strip the chlorine atoms
from the PCBs. The chloride ion content of the
sample is then measured using either a colorimetric
technique or an ion-selective electrode. The chlo-
ride ion concentration is used to calculate the PCB
content of the original sample. The detection limit
for PCBs in soil using commercially available kits
is near 10 ppm (4).
Sutcliffe and co-workers (25) have compared
colorimetric field kits (sodium reagent) (two kits
by determination for total chlorine with sensitivity
levels greater than 50 ppm and 500 ppm, respec-
tively) to laboratory instrumental thermal neutron
activation analysis as screening tools in a variety of
oil matrices. The colorimetric tests were shown to
be less reliable and more prone to interferences
than instrumental thermal neutron activation analy-
sis. The latter used thermal neutrons to irradiate
the PCB contaminated oil samples and Y-rays for
quantitative determination of total elemental halo-
gen content of the oil. Several limitations in using
the kits were pointed out, as well as cautions
against attempts to screen water samples. This
brings out the need to seek improvements for exist-
ing colorimetric field kits.
As mentioned earlier, the present research is
meant to advance the state-of-the-technology in
providing an attractive alternative to existing field
screening methods for PCBs.
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SECTION 4
APPROACH
OVERALL STRATEGY
Preliminary work toward development of a field
screening method for PCBs based on the reduction
of silver ion to silver metal was performed at the
Harry Reid Center (26). The present research is
meant to extend the early results toward a simple
method for practitioners faced with problems of
screening for PCBs in water and in following the
course of PCB soil remediation efforts.
One of the key elements of the research involved
extraction and concentration of PCBs from water
onto solid matrices suitable for visualization reac-
tions. The next step was to choose a chemical reac-
tion or a molecular association effect which would
give the operator a visual signal that PCBs are pre-
sent. The approach, outlined in Figure 2, involved
the use of SPE dipsticks to extract and concentrate
the PCBs.
The sections to follow outline the rationale that
was used to select in choosing the sample collec-
tion and visualization methodologies.
CHOICE OF THE PCB SAMPLE
COLLECTION TECHNIQUE
Liquid-liquid extraction (LLE) is often used as
the method of choice to isolate various organic pol-
lutants, including PCBs, from water. LLE, howev-
er, can be time consuming and labor intensive and
uses large volumes of solvents which subsequently
produce disposal problems. Therefore, interest in
replacing LLE with SPE is increasing.
SPE utilizes either columns containing solid sor-
bents or extraction membranes. Analytes are
sorbed onto the SPE matrix, extracted, then ana-
lyzed using GC, thin-layer chromatography (TLC),
or other techniques. The use of SPE membranes
provides advantages not found in columns. Their
use can reduce manual labor, speed sample pro-
cessing, and reduce the volume of solvent needed
for extraction (27-28). Several examples of utiliz-
ing membranes for the extraction and concentra-
tion of analytes from water exist in the literature.
For example, PCB-contaminated water has been
allowed to pass through SPE membranes, thus con-
centrating the PCBs (28). The PCBs were subse-
quently eluted from the membranes using small
VISUALIZATION
SOLID-PHASE EXT
Figure 2. An Approach in the Development of a Field Screening Method for PCBs in Water.
5
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volumes of organic solvent and analyzed using GC.
In another study, SPE membranes were utilized in
a dipstick mode (rather than filtration) for the
extraction of phthalates from water (29). The
phthalates were allowed to sorb onto the mem-
branes from contaminated water and were subse-
quently thermally desorbed and characterized
using ion mobility spectrometry (IMS).
In another study, direct solid-state fluorescence
was used to analyze anthracene sorbed from water
onto SPE membranes (30). One concept explored
in the present research involves sampling for PCBs
in water utilizing SPE membranes in a dipstick
mode with visualization of the sorbed PCBs using
a AgNO3 spray and UV light (Figure 2).
Another possibility applicable to higher concen-
trations of PCBs (as would be found in surfactant
solutions used for remediation of PCB contaminat-
ed soil) would be to use filter papers in a dipstick
mode, not to extract the PCBs but simply to wet the
paper with the test solution. Alternatively, drops of
the surfactant wash solutions could be placed onto
the substrates in preparation for the visualization
step. Use of both SPE membranes and filter papers
was examined in the present work. Emphasis was
placed on the dipstick mode.
CHOICE OF VISUALIZATION REAGENTS
A number of reports appeared in the 1970s on
the use of TLC for identification and, in some
cases, quantification of PCBs. The most often
cited visualization reagent was AgNO3, which was
used in combination with UV irradiation (Table 1).
Although sample processing and extraction were
normally required, sensitivities of 0.5-1.0 ppm of
PCBs in wildlife specimens, muscle tissue, egg,
and fat were easily attained (31-32). The visual-
ization effect is the appearance of a gray color.
Table 1. Citations on Using Thin Layer Chromatography and
AgNOa-UV Llghtfor the Detection of PCBs
Source
Sensitivity
Collins, 1972 (31)
Bush, 1973 (32)
Kawabata, 1974 (33)
Ismail, 1974 (34)
Mulhem, 1971 (35)
Abbot, 1969 (36)
Anderson, 1984 (37)
0.05 ng; 1 ppm
1 jig; 0.5 ppm
8-17 pg
1M-9
0.2 jid
10 ng; 0.01 ppm
1 mg (no AgN03)
Several papers have been published on the use
of diphenylamine as a visualization reagent. An
aluminum oxide Chromatography substrate con-
taining 1% diphenylamine exposed to 254 nm radi-
ation resulted in a fluorescence signal in the pres-
ence of PCBs; this was measured by scanning with
a densitometer (38-39). Another report described
the use of diphenylamine and zinc chloride to give
a light violet color with PCBs (40).
Based on a review of the available literature, it
was judged that the use of AgNO3 as a visualization
reagent afforded the best opportunity of meeting
the objectives of the report research.
DESIGN OF EXPERIMENTS
The design of experiments for the development
and optimization of a field screening test for PCBs
in water involved making certain decisions as well
as identification of the parameters to be investigat-
ed. Two test formats were chosen for sample col-
lection. .One involved dipping SPE membrane or
filter paper tabs into the test solution. In the other
format, drops of the test solution were placed onto
the filter paper tabs. Emphasis was placed on the
dipstick format. Other formats such as filtering the
test solution through SPE membranes could have
been used as well; however, discussions with the
sponsor and the proposed application of screening
effectiveness of soil remediation by washing with
aqueous surfactant led to the decision to keep the
procedure as simple as possible with little train-
ing of the operator being necessary.
A co-sponsor of this report research (General
Electric Corporate Research and Development) has
developed a proprietary process for remediation of
PCB-contaminated soil. Details are not available,
however, it was indicated that adding surfactants
(Neodol (R) 1-7 and Renex) to water increases the
solubility of PCBs to the 500 ppm level. In such
cases, sample concentration using SPE would not
seem necessary. However, experiments using SPE
to concentrate the PCBs were included to increase
the applicability of the test to other screening sce-
narios.
An early decision, which drove the design of
experiments for test development, was the choice
of the visualization reaction. As mentioned above,
a AgNO3 spray was chosen which led to color
changes as the result of silver ion reduction. This
decision was based on a review of the literature on
color reactions of PCBs, especially use of sprays
forTLC.
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Seven PCB analytes (as described in the
Experimental section) were chosen for testing. The
research experiments were divided into three major
areas dealing with interferences, sensitivity, and
optimization of procedures. A major interference
expected was chloride ion. This was confirmed and
will be described later. Experiments were designed
to eliminate the interference. Humic acid was
expected in organic soils and was also examined for
any deleterious effects. Eleven semivolatile and
volatile organic compounds, most containing chlo-
rine or bromine atoms, were also tested as interfer-
ences.
Effects on sensitivity focused on the nature of the
reaction matrices (i.e., ten different filter papers, one
TLC gel plate and one SPE membrane were
screened), the presence or absence of surfactants,
and the nature of added surfactants.
Experiments were also designed in an attempt to
optimize the test procedures. Effects of long and
short wavelength UV light on the silver ion reduc-
tion were examined. The use of TiO2 (a known pho-
tocatalyst) was checked for sensitivity enhancement
purposes.
Fluorescence emission spectra of AgNO3-PCB
mixtures were also checked to see if there was any
fluorescence enhancement. This might be an attrac-
tive alternative to the use of color change in applica-
tions where fluorescence instruments are available.
The various parameters, discussed above and uti-
lized in the design of experiments, are summarized
in Table 2. Not every parameter was checked against
every other parameter to the fullest extent in the test
plan. For example, not every one of the seven PCBs
was checked against each of the different filter
papers with each of the six surfactants.
Table 2. Parameters Utilized in the Design of Experiments for the
Development of a Screening Test for PCBs in Water
Test analytes
Sample collection
Choice of visualization
Interferences
Sensitivity
Optimization of test
procedures
Seven PCBs
SPE membrane
Filter paper
Dipstick mode
Placing test solution drops
onto the test matrices
AgNO spray followed by
UV light irradiation reaction
Chloride ion
Humic acid sodium salt
Seven semivolatile organic
compounds
Four volatile organic compounds
SPE membrane
. Ten different filter papers
Present/absence of surfactants
Nature of added surfactants
Short vs. long wavelength UV light
Potential use of Ti02 for sensitivity
.enhancement
Fluorescence enhancement
vs. color change
However, it has been judged that the tests chosen
were more than sufficient to establish the sensitivi-
ty range, to appreciate what interferences to expect,
to understand how the test might be utilized, and to
form a base of information for test improvements.
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SECTION 5
EXPERIMENTAL
REAGENTS AND MATERIALS
Silver nitrate (AgNO^, humic acid (sodium salt,
reagent grade, technical), Triton X-100
(CH3C(CH3)2CH2C(CH3)2C6H4(OCH2CH2)XO
H, X = 10 (avg)), Triton X-100 (reduced)
(CH3C(CH3)2CH2C(CH3)2C6H8(OCH2CH2)X
OH, X = 10 (avg)), and Triton X-405 (reduced)
(CH3C(CH3)2CH2C(CH3)2C§H4(OCH2CH2)X
OH, X = 40 (avg)) were obtained from Aldrich
Chemical Company, Inc., Milwaukee, Wisconsin.
Dow Coming Z-6020 silane (aminoelhylamino-
propyltrimethoxysilane) was a sample from Dow
Coming, Midland, Michigan. Sodium chloride
was obtained from Mallinckrodt, Paris, Kentucky.
Methanol (high purity solvent) was purchased from
Burdick & Jackson, Muskegon, Michigan. PCBs
(Aroclors 1016,1221,1232,1242,1248,1254, and
1260) were gifts of the U.S. EPA Environmental
Monitoring System Laboratory, Las Vegas,
Nevada. These are authentic PCB samples of qual-
ity assurance purity drawn from the U.S. EPA
Quality Assurance Materials Bank. Anion
exchange resin and membrane were brought from
Bio-Rad Laboratory, Richmond, California. 4-
Bromobiphenyl, 1-bromohexane, 1-bromodode-
cane, 1-chlorobenzene, 1-chlorohexane, and 1-
chloronaphthalene were from Eastman Kodak
Company, Rochester, New York. Deionized water,
CHC13, CC14, OjCHCHC^, CHpLj, TiO2, and
biphenyl, were obtained from the Chemistry
Department, UNLV.
Neodol (R) 1-7 (a Cu alcohol ethoxylate with an
average of 7 moles of ethylene oxide per mole of
alcohol) and Renex KB (a polyoxyethylene alkyl
alcohol) are products of the Shell Chemical Co.,
Houston, Texas, and ICI Americas Inc.,
Wilmington, Delaware, respectively. Samples
were obtained from General Electric Corporate
Research and Development, General Electric Co.,
Schenectady, NY. The composition of all of the
surfactants used is given in Table 3.
Table 3. Composition of Surfactants
Surfactant
Composition
Neodol R 1-7
Renex KB
Triton X-100
Triton X-100
(reduced)
Triton X-405
(reduced)
Dow Corning
Z-6020
a C,, alcohol ethoxylate with an average of
7 moles of ethylene oxide per mole of alcohol
a polyoxyethylene alkyl alcohol
(OCH2CH2)XOH,X = 10(avg)
(OCH2CH2)XOH, X = 10 (avg)
(OCH2CH2)XOH, X = 40 (avg)
aminoethylaminopropyl-
trimethoxysilane
The SPE membranes, C-18 Empbre™, were
obtained as disks from Analytichem International,
Harbor City, California, with a composition of 90%
(by weight) of octadecyl (ClS)-bonded silica parti-
cles and 10% polytetrafluoroethylene (PTFE).
Filter papers (Whatman 1, 40, 42, 541, 542) and
silica gel plates for TLC (Whatman) were from
W&R Balston Limited, Maidstone, England;
S&S 604 and S & S 2043A filter papers were from
Carl Schleicher & Schuell Co.; S/P filter paper
(F2406-125) was from American Hospital Supply
Corporation, Evanston, Illinois; VWR filter paper
(catalog number 28320-143, grade 615) was from
VWR Scientific Inc., Mt. Holly Springs,
Pennsylvania; printing paper (Matrix, Xerographic
D.P. Hi-Speed White 434236) was from
Zellerbach. All filter papers were available from
the HRC, UNLV.
EQUIPMENT
The UV portable light source utilized in the
visualization experiments (Mineralight Lamp-
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Model UVG-11,254 nm) was obtained from Ultra-
violet Products, Inc., San Gabriel, California. A
viewing box containing both 254 and 365 nm light
sources (9818"^eries Darkroom) was from Cole-
Parmer Instrument Co., Chicago, Illinois. The
spectrofluorometer (Spex Fluorolog-model 1680)
was from Spex Industries, Inc., Edison, New
Jersey; the light sources were 450 W xenon lamps.
TEST PROCEDURES
Tabs (1 x 1 cm) were cut from the filter papers
or SPE membrane disks. Solutions of the PCBs
were prepared in methanol and diluted to different
concentrations with deionized water with and with-
out surfactant. The control solutions also con-
tained surfactants if used in the tests. The surfac-
tant concentrations are given by weight percent.
The SPE tabs were conditioned by dipping into
methanol immediately before use. This allowed
them to be wet easily by the aqueous test solutions.
The SPE tabs were either suspended in the various
PCB test solutions for 30 minutes or dipped into
them and quickly removed. The tabs were sprayed
with 0.059 M AgNO3 in methanol and irradiated
with UV light (254 nm) for 1-3 minutes. The
development of color relative to a control tab after
1 minute served to indicate the presence of PCBs.
The filter paper tabs (1 x 1 cm) were dipped into
the PCB test solutions, removed, sprayed with
0.059 M AgNO3 methanplic solution, and exposed
to UV light (254 nm) for 3 minutes in the same
manner as mentioned above. The distance between
the lamp and filter paper tabs was 1.5 cm.
Interference testing followed the same proce-
dure except for very volatile analytes, in which
cases, quartz plates were used to cover the test tabs
during the UV irradiation and color development
stages. The interferences which were tested in this
research were chloride ion, humic acid, biphenyl,
1-chloronaphthalene, 1-chlorobenzene, 4-bromo-
biphenyl, 1-bromohexane, 1-chlorohexane, 1-bro-
mododecane, CHC13, CC14,
and
Ameritone paint color sheets were employed as
standards for defining the exact color and intensity.
All results were based on at least duplicate runs,
but mostly triplicate.
FLUORESCENCE MEASUREMENTS
Emission spectra were measured with excitation
at either 254 or 290 nm, depending on the experi-
ment. Tabs (1 x 2 cm) were examined on their
front surfaces with excitation and emission band-
passes at 4.25 and 2.13 nm, respectively. S & S
2043 A filter paper was chosen based on reports
that it gave high RTP yields with PCBs (23-24).
Whatman 541 filter, paper was examined as well.
Various concentrations of PCB-1232 (0, 1, 10, 100
ppm) in aqueous solution containing 3% by weight
Renex KB surfactant were examined.
A 5.0 uL aliquot of the PCB solution was spot-
ted onto the center of a filter paper tab. The tab
was placed onto a glass slide, dried under an
infrared heat lamp for 5 minutes and its emission
spectrum measured. A 5.0 uL aliquot of AgNO3
solution was then spotted onto the center of the tab,
followed by heat lamp drying, and spectral mea-
surement. This procedure was reversed in some
experiments wherein the AgNO3 solution was spot-
ted first.
-------
SECTIONS
RESULTS AND DISCUSSION
USE OF SOLID PHASE EXTRACTION
(SPE) MEMBRANES
Initial results indicated that the use of SPE
membranes in combination with the AgNO, visual-
ization reaction leads to detection of PCBs in water
(not containing surfactants) at the 0.5-1.0 ppm
level. This was when the SPE tabs were allowed to
remain in the test solutions for one hour in a pas-
sive mode. Allowing the SPE tabs to remain in the
solutions for 22-24 hours did not improve the sen-
sitivity. Decreasing the tab exposure time to 30
minutes raised the detection limit to 5 ppm.
Methanol was used to initially dissolve the PCB
samples as part of the test solution preparations.
However, it is suspected that adsorptive losses
occurred on the surfaces of the glass containers
used for the experiments, irrespective of the pres-
ence of methanol, since the PCB concentrations
were near or over their solubility limits in water.
Absorptive losses of PCBs on glassware are well
documented (4). Due to this loss, the detection
limits observed in the initial experiments in the
absence of surfactant are undoubtedly high.
However, if wall loss was significant, longer expo-
sure of the tabs should have made a difference; this
was not noted.
SPE membranes were also employed to extract
PCBs from aqueous solution containing surfactant
by suspending tabs in the test solutions for 30 min-
utes (Table 4). The detection limit was found to
vary between 0.5-5 ppm depending on the PCB.
This compares well to the preliminary results with-
out surfactant.
EXAMPLES OF FINDINGS USING FILTER
PAPERS
Examples of experimental results for PCB deter-
mination in aqueous surfactant solutions are given
in Tables 5-6. The results were obtained by dip-
ping Whatman 541 tabs into aqueous solutions
containing various PCBs and either Renex KB or
Neodol (R) (1-7) surfactants, removing the tabs
quickly, adding AgNO3, and irradiating the tabs
with UV light. These particular surfactants were
emphasized throughout the research because of the
interest of the co-sponsor (General Electric
Corporate Research and Development) in their use
in remediation of PCB-contaminated soil. The
numbers and tones (e.g., 2H56G Lustre Beige)
refer to Ameritone™ paint color sheets as men-
tioned in the Experimental section.
The results given in Tables 5 and 6 show that
PCBs can be detected on Whatman 541 filter paper
in the presence of relatively high concentrations of
the surfactants Renex KB or Neodol (R) 1-7. The
colors differed somewhat depending on the PCB
and the surfactant. There does not appear to be a
trend showing that the PCBs containing either a
higher or lower percentage of chlorine are more
easily detectable. At 500 ppm PCB concentrations
the test colors were basically brown with some
gray being evident. It was interesting to find that
the control tabs showed very little color even
though the solutions contained 3% surfactant.
The sensitivity limit in detecting various PCBs
in solutions containing either Renex KB or Neodol
(R) 1-7 was 1.0 ppm (Tables 7 and 8).
It is also interesting to note that dipping the fil-
ter paper Whaitman 541 tabs and quickly removing
them is about as sensitive as the technique in which
SPE tabs (in. the presence of surfactant) were
allowed to stand for 30 minutes. The surfactant
may be competing with the PCBs for sorption onto
the SPE medium.
An experiment was performed to determine
whether the presence of surfactant had an effect on
the test sensitivity. Using PCB-1232 and Whatman
541 tabs in the presence and absence of Neodol (R)
1-7, no difference was found. PCB-1232 was
detected at 1 ppm in both cases.
EFFECT OF INTERFERENCES
Chloride Ion. It was expected that CT would
interfere in the visualization reaction since AgCl
10
-------
Table 4. Results with PCBs Using SPETabs Suspended for 30 Minutes In Test Solutions Containing 3% Surfactant
PCB-1232
(R)1-7Neodol
PCB-1254
Neodol
(R)1-7
PCB-1221
Renex KB
PCB-1232
Renex KB
0 ppm 0.1 ppm
Negative Negative
Negative Negative
Negative Negative
Negative Negative
0.5 ppm 1 ppm 5 ppm
10 ppm
Sensitivity
Negative Negative Light gray, Light gray, 5 ppm
lighter than 1H50F similar to 1H50F
Shagbark Shagbark
Very light Light gray, Gray, Dark gray, 0.5 ppm
gray, similar to similar to lighter
similarto 1H49F 2M41DDawn than2M42D
2H45G Taupe Phantom Coffee Tint
Negative Negative Very light gray, Very light gray, 5 ppm
similar to 1H49F similar to 1H50F
Taupe Shagbark
Negative Light gray, Light gray, Light gray, 1 ppm
.- . a little similar to 1H49F similar to 1H50F
lighter than Taupe Shagbark
2H45G Water
Table 5. Test Results with PCBs Using Whatman 541 Tabs and 3% Renex KB
PCB-1016
PCB-1221
PCB-1232
PCB-1242
PCB-1248
Oppm
Negative
Negative
Negative, lighter
than 2H56G Lustre
Beige,
Negative,
lighter than
2H56G Lustre Beige
Negative ,
1 ppm
Negative
Negative
Very light gray,
lighter than 2M40E
Liquorice Tint
Light gray,
lighter than
Phantom
Negative
10 ppm
Light gray
Light gray
Light gray, similar
to 2M40E Liquorice
Tint
Light gray,
similar to
2M41DFawn
Phantom
Very light gray
100 ppm
Gray
Light gray
Light gray, similar
to 1M50E Dolphin
Gray,
a little
darker than
2M39D Meteor
Gray
500 ppm
Brown, some gray
Brown, some gray
Brown, some gray
Table 6. Test Results with PCBs Using Whatman 541 Tabs and 3% Neodol (R) 1 -7
PCB-1232
PCB-1242
PCB-1248
PCB-1254
Oppm
Negative
Negative, lighter
than 2H45F Warm
Beige
Negative,
lighter than
2H45FWarm
Beige
Negative
1 ppm
Very light gray
Very light gray,
lighter than 2M43E
Gobi
Very light gray,
a little grayer
than 2M43E
Gobi
Light gray
10 ppm
Light gray
Light gray, a little
lighter than 2M41D
Fawn Phantom
Light gray, a little
lighter than
2M41DFawn
Phantom
Light gray
100 ppm
Light gray
Gray, a little grayer
than 2M42D Fawn
Phantom
Gray, lighter than
2D40C Drake,
darker than
2M39D Meteor
Gray
500 ppm
Brown, some gray
Brown, some gray
1-1
-------
Table 7. Results of Sensitivity Experiments Using Whatman S41 Tabs and 3% Renex KB
Oppm
0.5 ppm
1 ppm
Sensitivity
PCB-1232
PCB-1242
PCB-1248
PCB-1254
Negative
Negative, lighter
than 2H45F Warm
Negative,
lighter than
2H45FWarm
Beige
Negative
Negative
Very light gray,
lighter than 2M45F
Warm Beige
Negative, lighter
than 2H45F
Warm Beige
Negative
Very light gray
Very light gray,
a little grayer
than 2M43E Gobi
Very light gray,
a littler grayer
than 2M43E Gobi
Light gray
1 ppm
1 ppm
1 ppm
1 ppm
Table 8. Results of Sensitivity Experiments Using Whatman 541 Tabs and 3% Neodol (R) 1-7
PCB-1232
PCB-1242
PCB-1248
Oppm
Negative
Negative, lighter
than 2H45F Warm
Beige
Negative
0.5 ppm
Negative
Negative, lighter
than 2M45F
Warm Beige
Negative,
lighter than 2H45F
Warm Beige
1ppm
Very light gray
Very light gray,
a little grayer
than 2M43E Gobi
Very light gray
Sensitivity
1ppm
1 ppm
1 ppm
PCB-1254
Negative
Negative
Light gray
1ppm
would be formed and is sensitive to light. The
interference of CL~ was confirmed using Whatman
541 tabs in the absence of surfactants.
The sensitivity for Q- was found to be 1
ppm. No color was observed at the 0.5 ppm level.
Positive tests were found with PCBs at the 0.5 ppm
level but this is understandable since the equivalent
a content in the PCBs would be at a higher con-
centration. The colors matched closely those
obtained using PCBs, i.e., very light gray at 1 ppm
and brown at highest concentrations (in this case,
1000 ppm CL).
The CT interference was eliminated by adding a
few granules of an anion exchange resin (AG 1-
X2) to the test solution, lightly agitating, and per-
forming the test in the usual manner. The results
were negative up to 1000 ppm Or.
The anion exchange resin (0.1 g) was also added
to 1 mL solution containing 3% Neodol (R) 1-7
and various concentrations of PCB-1232 (1-500
ppm) in the absence of Cl~. The detection limit for
PCB-1232 in the presence of the Neodol was found
to be 1 ppm as mentioned earlier (Table 6).
However, in the presence of the anion exchange
resin, the limit was raised to 10 ppm implying
sorption of the PCB by the resin. It is judged that
the detection limit could be lowered to 1 ppm with
optimization of the amount of resin used; however,
this was not pursued. It was important to find that
Cl' interference could easily be removed by using
an anion exchange resin.
It was also found that Q- interference could be
removed by simply washing the filter paper tabs
with distilled water. Unfortunately, PCBs were
also removed easily from the paper. This was also
true for SPE tabs that were dipped into PCB solu-
tions and quickly withdrawn. However, PCBs are
not removed to any extent from SPE tabs that have
been exposed to PCB solutions for a period of time
or from SPE membranes through which the PCB
solutions have been allowed to filter. An organic
solvent is required to remove the PCBs. Therefore,
in cases of high contamination by Cl% the use of
SPE tabs for PCB sorption for a period of time fol-
lowed by a water wash may be very attractive.
12
-------
Organic Compounds. Seven volatile and semi-
volatile compounds and one nonvolatile organic
compound were tested initially as interferences
(Table 9). They are listed by order of reactivity to
AgNO3-UV visualization with the least reactive
being shown first. One of the major interferences
that might be expected in ground water in the
vicinity of high organic content soil is humic acid.
However, this posed the least interference among
the compounds tested, even at 1000 ppm. Humic
acid was also added to PCB test solutions but was
not found to interfere up to 500 ppm. A pink back-
ground became evident at 1000 ppm.
Several of the compounds, including biphenyl,
showed light pink colors at 100 ppm. With the
PCBs, pink colors were not found. Therefore,
these would not be considered as serious interfer-
ences. However, it is clear that most aromatic and
aliphatic compounds containing halogen (either Cl
or Br) should be expected to interfere. In field
screening scenarios, the sites have already been
characterized and the pollutants are known. In
remediation processes, the target compounds are
known as well. If there are a number of
organohalogen pollutants, the AgNO3-UV proce-
dure can serve as a class test. However, not all
organochlorine compounds will necessarily react
readily. Four volatile compounds (CHC13, CC14,
CLjCHCHClj, and CH^Cy were investigated as
neat liquids on Whatman 541 tabs. A drop of
methanolic AgNO3 was placed on the tab contain-
ing the neat liquid; the tab was covered with a
quartz plate and irradiated for 30 seconds using
254 nm light. Carbon tetrachloride developed the
most color (Table 10). Tests were also performed
with CC14 diluted in methanol. However, no dif-
ferences were observed in comparison with the
blanks up to 3000 ppm, i.e., the test is much more
sensitive for PCBs than for CQ4.
EFFECT OF MATRIX
Ten filter papers, one SPE membrane, and one
TLC silica gel plate were examined as matrices for
the AgNO3-UV visualization test using PCB-1232
in solutions containing 3% Neodol (R) 1-7. Most
Table 9. Interference Test Results Using Whatman 541 Tabs and Neodol (R) 1-7
Interterant
Humic Acid,
Sodium Salt
Oppm
Negative
1ppm
Negative
10 ppm
Negative
100 ppm
Negative
500 ppm
Very light pink
1000 ppm
Light pink
Biphenyl
1-Chloronaphthalene
1-Chlorobenzene
4-Bromobiphenyl
1-Bromohexane
1-Chlorohexane
1-Bromododecane
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Very light
gray
Marginal
Negative
Negative
Almost blank
Very light gray
Light gray
Some gray,
some pink
Light gray
Light brown
Very light pink
Light pink
Light gray
Light gray
Some brown,
Some pink
Gray
Some brown
Unstable color
Unstable color
Table 10. Test Results with Neat Organochloro Liquids Using Whatman 541 Tabs
Coloration
Control
Negative
CHCl,
Very light
CCl4
Gray, a little
CI2CHCHCI2
Light brown,
CH2CI2
None
brown, some
gray similar
to2M56E
County Garden
little darker
than
.1M49D
Sandal Grove
some yellow
browner than
2M56E County
Garden
13
-------
of the papers and the TLC plate gave colors in the
absence of PCB. These ranged from grays to
browns of different shades and intensities (Table
11). As shown in the Table 11, the background
interfered with no differences in color being
detectable between the blanks and the tests up to
100 ppm of the PCB.
Whatman 541 filter paper gave a negative blank.
The blank for Whatman 542 was a very light gray,
but the background did not interfere with the PCB
test and did not raise the detection limit. The blank
with the C-18 Empore™ SPE membrane was also
negative. Whatman 541 appears to be the best
choice among the filter papers examined and was
used in most of the experiments, many of which
were described earlier.
Whatman filter papers 541 and 542 are hardened
ashless papers manufactured for use under strong
acid or alkaline conditions. Filter paper 541 is for
large or gelatinous precipitates. Filter paper 542 is
for high retention of fine particles. Whatman 1 is a
classic general purpose filter paper. Whatman 40
and 42 are ashless papers. Paper 40 is a general
purpose gravimetric one, while paper 42 is for
extremely fine precipitates. No information was
found on chemical composition or any additives
which might be present.
It is clear that many matrices may be expected to
increase the sensitivity of Ag+ to photodegradation.
In continued development of the visualization test,
it seems worthwhile to screen a large number of
different types of TLC plates, membranes, and
papers. It is expected that improvement might be
made in test sensitivity by finding an optimum bal-
ance of matrix properties between acceptable
blanks and enhancement of photosensitization.
Possible candidates are glass fiber paper and
hydrophilic polypropylene membrane which do not
give responses in preliminary blank determinations.
EFFECT OF SURFACTANT
Table 12 gives test results with PCB-1232 solu-
tions containing different surfactants. Triton X-
100 gave a blank response which masked the PCB
test results, at 1 and 10 ppm. The Dow Corning Z-
6020 blank response completely masked the test
results. This is not surprising. Triton X-100 con-
tains an aromatic ring which would be expected to
complex with Ag+. The Dow Corning material
contains amino groups which should complex
readily with Ag+ and facilitate photodegradation.
Triton X-100 (reduced) and Triton X-405
(reduced) contain cyclohexyl rings. These com-
pounds seem to inhibit the photodegradation with
an overall effect of raising the detection limit for
the PCB to 10 ppm and 100 ppm, respectively.
The Neodol (R) 1-7 and Renex KB gave accept-
able blank responses with the latter giving a slight
coloration. It was interesting to find that use of a
mixture of surfactants (Neodol (R) 1-7 and Triton
X-100 (reduced), each 1.5% by weight in the solu-
tions), led to a decrease of the detection limit for
PCB-1232 to 0.5 ppm using either Whatman 541 or
C-18 Empore™ SPE tabs; the UV exposed time
was three minutes (Table 13). Whatman 42 tabs,
which were previously found to cause high blanks,
continued to do so but the colors differed some-
what.
The choice of surfactant will undoubtedly be
driven more by effectiveness in remediation of
PCB contaminated soil rather than by impact on a
field screening test. It was fortunate to find that
Neodol (R) 1-7 and Renex KB did not adversely
affect the AgNO3-UV visualization test since these
compounds are currently being used for soil remedi-
ation.
REACTION MECHANISM
The mechanism of the visualization reaction
most likely, involves complexation of the PCBs
with silver ion followed by reduction to Ag metal
(Figure 3). -Various studies have led to the conclu-
sion that Ag+ forms complexes with aromatic rings
(12-14). Crystals of a AgQO4 complex with ben-
zene have been isolated (41). Complexes of PCBs
with Ag+ undoubtedly occur as well, though stabil-
ity may vary depending on the PCB isomer and the
number of Cl atoms. If Ag+ complexes of PCBs
involve K electron bonding (as with benzene), then
PCBs with greater numbers of Cl atoms should
yield less stable complexes. The photodegradation
of silver salts to silver metal has been known for
many years. It is clear from the results of the cur-
rent research that the presence of PCBs accelerates
the photodegradation.
Many reports are available on the dechlorination
of PCBs under the influence of light (e.g., 15-17,
42-44). There have been various studies on
enhancing the photodechlorination. For example,
surfactants and sodium borohydride have been
found to be useful (43). Silver ion may enhance
the photodechlorination and form AgCl. Direct
14
-------
Table 11. Test Results with PCB-1232 Using Different Matrices with 3% Neodol (R) 1-7
Whatman 1
Whatman 40
Whatman 42
Whatman 541
Whatman 542
S&S604
S & S 2043A
S/P
VWR
C-18 Empore™
Matrix
printing paper
Plate for TLC
(silica gel)
Oppm
A little gray,
brown (little
browner than
1D47C King Bird)
Brown, similar to
2M42Z Silver Mushroom
Very light gray,
lighter than 2M42D
Fawn Phantom
Negative
Very light gray,
similar to 2M45E Gobi
Pink, similar to 2M46D
Solomon Sand
Dark gray, darker than
2Y34ATara
Gray, some brown,
a little browner
than 2D40C Drake
Dark gray,
darker than
2M40C Drake
Negative,
similar to 1H50G
Autumn Acorn
Brown,
lighter than
2U48B Rocket
Dark brown,
similar to
2UM25A Brigadoo
1 ppm
A little gray,
brown (little
browner than
1D47C King Bird)
Brown, similar to
2M42Z Silver Mushroom
Very light gray,
lighter than 2M42D
Fawn Phantom
Very light gray
Light gray, a little
lighter than 2M41D
Fawn Phantom
Pink, similar to 2M46D
Solomon Sand
Dark gray, darker than
2Y34ATara
Gray, some brown,
a little browner
2D40C Drake
Dark gray,
darker than
2M40C Drake
Very light gray,
similar to
1H50FShagbark
Brown,
lighter than
2U48B Rocket
Dark brown,
similar to
2UM25A Brigadoo
10 ppm
A little gray,
brown (little
browner than
1D47C King Bird)
Brown, similar to
2M42Z Silver Mushroom
Very light gray,
lighter than 2M42D
Fawn Phantom
Light gray
Light gray, similar to
2M41D Fawn Phantom
Pink, similar to 2M46D
Solomon Sand
Dark gray, darker than
2Y34ATara
Gray, some brown,
a little browner
2D40C Drake
Dark gray,
darker than
2M40C Drake
Light gray,
similar to 2M40E
Liquorice Tint
Brown,
lighter than
2U48B Rocket
Dark brown,
similar to
2UM25A Brigadoo
100 ppm
A little gray,
brown (litle
browner than
1D47C King Bird)
Brown, similar to
2M42Z Silver Mushroom
Light gray,
similar to 2M41D
Fawn Phantom
Light gray,
similar to 2M41D
Fawn Phantom
Gray, some brown
similar to 2M45D
Sand Stream
Pink, similar to
2M46D
Solomon Sand
Dark gray, darker than
2Y34ATara
Gray, some brown,
a little browner
than 2D40C Drake
Dark gray,
darker than
2M40C Drake
Gray,
similar to 2M42E
Silver Mushroom
Brown,
lighter than
2U48B Rocket
Dark brown,
similar to
2UM25A Brigadoo
15
-------
Tabte 12.Test Results with PCB-1232 Using Whatman 541 Tabs and Different Surfactants (3%)
0 ppm 1 ppm
Triton X-100 Some yellow, Some yellow,
some black some black
Triton X-100, Negative, Negative,
reduced darker than similar to 2H30P
2H30PAiry Airy
Triton X-405, Negative, Negative,
reduced almost white almost white
Dow Corning Brown, Brown,
Z-6020, Silane darker than 2U41B darker than 2U41 B
Brown Benedictine Brown Benedictine
Neodol (R) 1-7 Negative Very light gray
Renex KB Negative, lighter Very light gray,
than2H56G lighter than
Lustre Beige 2M40E Liquorice Tint
10 ppm
Some yellow,
some black
100 ppm
Gray
Light gray, Gray,
lighter than similar to
6M41 D Fawn Phantom 2M40E Liquorice Tint
Negative,
almost white
Gray
Brown, Brown,
darker than 2U41B darker than 2U41B
Brown Benedictine Brown Benedictine
Light gray
Light gray,
similar to 2M40E
Liquorice Tint
Light gray
Light gray,
similar to
1M50E Dolphin
ablt 13.Test Results with PCB-1232 on Different Matrices Using a Mixture of 1.5% wt Triton X-100 (reduced) and 1.5% wt Neodol (R) 1-7
0 ppm 0.5 ppm
Yhatman 541 Negative, Light gray,
similar to 1 H50G lighter than
Autumn Acorn 1 H50F Shagbark
r18Empore™ Negative, Light gray,
lighter than similar to 1 H59F
2H40G Taupe
Yhatman 42 Light brown, Light brown,
similar to 2M43E similar to 2M43E
Gobi Gobi
5 ppm
Light gray,
similar to 1H50F
Shagbark
50 ppm
Gray,
similar to 2M40E
Liquorice Tint
Light gray, Gray, some brown
a little darker similar to 2M41 D
than 1H59F Taupe Fawn Phantom
Light brown,
similar to 2M43E
Gobi
Gray,
similar to 2M41D
Fawn Phantom
^ /^
Cly Oly
PCBs
r
JS
AgCI
«/
' \f
_J!M^ Ag°
-------
reduction of Ag* by the PCB under influence of
light is possible but a less likely mechanism in
view of what has been reported on PCB pho-
todegradation giving Ch
Humic acid also has aromatic rings; however, it
did not sensitize the photodegradation of Ag+.
Humic acid is a large and complicated molecule.
The benzene rings may not be readily available.
Biphenyl gave a weak response at 100 ppm
(Table 9). It is also clear from the interference test-
ing that an aromatic ring is not necessary. Several
aliphatic bromo and chloro compounds also gave
the color. However, the lowest detection limits
were obtained with PCBs.
EFFECT OF LIGHT WAVELENGTH
A,UV viewing box, equipped with 254 and 365
nm light sources, was used to check the effect of
wavelength on the visualization of sodium chloride
on Whatman 541 tabs. The use of 365 nm light
gave a response, but it took three times longer than
with the 254 nm source. There is no par-
ticular advantage in using the longer wavelength
light. Sunlight through a window is also effective,
but the intensity was very high on the particular
day the experiment was run, and the control tabs
changed color upon being exposed to sunlight after
1 minute.
Choice of light intensity is a consideration. The
254 nm lamp in the UV box was less intense than
the portable lamp normally used. Irradiation for 3
minutes of Whatman 541 tabs containing sodium
chloride gave a detection limit of 10 ppm, whereas
a limit of 1 ppm was found with the portable lamp.
EFFECT OF TITANIUM DIOXIDE
A possible approach to sensitivity enhancement
is to utilize a photocatalyst to facilitate dechlorina-
tion of the PCBs. A photocatalyst which has been
investigated for both oxidation and reduction reac-
tions is TiO2 (47-48). Several experiments were
performed with TiO2 using PCB-1232. For exam-
ple, TiO2 was deposited on Whatman 541 paper by
filtering a suspension of TiO2 in AgNO3 solution
through it. A drop of the PCB test solution was
placed on the paper followed by UV irradiation.
The amount of TiO2 and AgNO3, pH and the tech-
niques were varied. Unfortunately, high blanks
were observed. Colors were obtained in as little as
6 seconds with 365 nm irradiation. The TiO2 was
found to be an exceptionally good photocatalyst for
the reduction of Ag+. Use of TiO2 in the absence of
Ag+ showed no color with PCB-1232 on irradia-
tion with 254 nm light for 30 seconds. The use of
a catalyst for the dechlorination of PCB as part of
a field screening test is still judged to be a good
idea but requires additional experimentation.
RESULTS WITH SAMPLES FROM SOIL
REMEDIATION
One of the co-sponsors of this work, General
Electric Corporate Research and Development, has
developed a proprietary process for remediation of
soils contaminated with PCBs by washing with
surfactants. Details of the process are not avail-
able, but two of the surfactants being used are
known since samples were supplied for this inves-
tigation. The use of surfactants in solution above
their critical micelle concentrations to increase the
solubility of hydrophobic compounds is known. It
was mentioned by the sponsor that the soil wash-
ings could contain PCBs at the 500 ppm level. A
recent paper on use of surfactants to remediation
soil mentioned that PCB-1260 has shown an
increase in solubilization of 660,000 times relative
to that in water alone (49).
Ten samples of surfactant solutions of PCB-
1260 from soil washing operations using 2%
Renex KB surfactant were received from General
Electric Corporate Research and Development.
The samples contained some sediment which was
allowed to settle. Test samples were withdrawn
from the top. Half of the samples had a PCB con-
centration of approximately 10 ppm and the other
half approximately 40 ppm. These were not based
on analyses but on differences between analyses of
soil samples before and after a wash. All contained
Renex KB surfactant at the 2% level.
The procedure described previously was fol-
lowed except that pieces of anion exchange mem-
branes were added to the test solutions to eliminate
any Cr interference. Solutions of PCB 1260 at 10
ppm and 40 ppm, containing 2% Renex KB, were
used as controls. There was no difficulty in differ-
entiating the test samples by level of concentration.
However, the colors obtained with the General
Electric samples were darker than expected when
compared to the controls. The colors from the
General Electric 10 ppm and 40 ppm samples were
closer to colors expected from 40 ppm and 400
ppm, respectively. A control soil wash, i.e., the
surfactant wash from an equivalent clean soil was
not available. Therefore, it is not known whether
17
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an interference might have been caused by a com-
ponent from the soil. Also, it is not known whether
other ingredients were present in the soil wash.
Though the test results were high, they were
promising. Of course, the possibility exists that
they were higher concentrations than labeled, but
the solutions were not analyzed. If the tabs had
been performed on site, more information would
have been available, and appropriate changes to the
test and/or the color interpretation most likely
could have been made on the spot.
BLIND SAMPLE TEST
Five blind samples were prepared by co-worker
Robert L. Curiale. At low concentrations, the
results (Table 14) were very good. Two samples
that were reported at concentrations of 5 ppm and
30 ppm were actually 3 ppm and 25 ppm, respec-
tively. The three remaining samples were reported
at best between 100 and 500 ppm; their colors were
indistinguishable amongst one another. In actuali-
ty, they were 175, 325, and 450 ppm.
TaWa 14. Results of Blind SamplaTest
Actually
Con.
Estimated
Con.
3 ppm 25 ppm 175 ppm 325 ppm 450 ppm
5 ppm 30 ppm 100-500 100-500 100-500
ppm ppm ppm
FLUORESCENCE MEASUREMENTS
Fluorescence measurements were performed
with PCB-1232 solutions containing 3% Renex
KB on Whatman 541 andS&S 2043 A filter papers
to see if spraying with AgNO3 would enhance the
PCB fluorescence. If so, it might offer the oppor-
tunity to decrease the detection limit.
The S & S 2043A paper prepared from 1, 10,
and 100 ppm solutions of PCB-1232 gave emission
peaks at 326 nm using 290 run excitation.
Excitation at 254 nm gave a peak at 316 nm.
Spectra obtained using control solutions without
PCBs confirmed that the emission peaks were from
the PCB.
Whatman 541 filter paper was one of the best for
the visualization experiments but did not serve as a
useful matrix for fluorescence measurements. No
emission was found for papers prepared from 10
ppm solutions of PCB-1232. Spotting AgNO3
solution onto the PCB tabs did not lead to the
appearance of any peaks above the background of
the paper.
Spotting the S & S 2043A filter paper contain-
ing PCBs with methanolic AgNO3 led to complete
quenching of the emission (Figure 4). This may
not be surprising since the paper itself photosensi-
tizes the reduction of Ag+. Silver metal may be
serving to mask the PCB fluorescence. S & S
2043A is one of the best paper substrates for mea-
surement of solid state PCB emission and RTP but
interferes in the visualization test. Several modifi-
cations were made in the procedure such as spot-
ting the AgNO3 first, followed by the PCB.
However, this was not successful.
The fluorescence experiments were not pursued
further.
300
350 400 450
EMISSION WAVELENGTH (nm)
500
Figure 4. Solid State Emission Curves of 10 ppm PCB-
1232 with 3% Renex KB on Tabs of S & S 2043A Filter
Paper Before and After Adding 0.059 M AgNO3 in
Methanol Solution.
IMPLICATIONS FOR FIELD SCREENING
The basic idea of using simple sample handling
methods in combination with visualization tech-
niques to detect PCBs in water is attractive for field
screening applications based on results of the pre-
sent research. The method developed in this
research is rapid, simple, and of low cost. It
appears adaptable in detecting from 0.5 to 500 ppm
or more of PCBs in soil remediation scenarios
where relatively high concentration of surfactant
are present. Use of simple color charts can be used
to determine whether PCBs are present or absent
above or below a predetermined threshold at a par-
ticular site.
18
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If ppm contamination of PCBs is suspected, the
sample can be collected by using a filter paper dip-
stick or by placing drops of the test solution onto
paper tabs. If ppb concentration are suspected,
SPE techniques will have to be utilized. SPE dip-
sticks can be placed into the solution and allowed
to stand for a period of time or the solution filtered
through the SPE membranes. The sample handling
is summarized in Figure 5 as a decision tree.
One potential barrier to the utility of this proce-
dure for PCBs is the interference of other
organohalogen compounds. However, the method
could be expanded to field screening for
organohalogen compounds in general if they were
suspected to be present.
There are many tradeoffs in choosing methods
for field screening and measurements, including
cost, response time, sensitivity, selectivity, size,
and weight. Figure 6 gives a comparison of
GC/MS, immunoassay, and AgNO3/UV methods
for several of the major tradeoffs in screening for
PCBs. GC/MS and immunoassay stand out in
selectivity and sensitivity, whereas the AgNO3/UV
procedure appears attractive relative to factors of
cost, time, and simplicity. It would be very use-
ful in the next development stage to perform the
test in the field in a soil remediation scenario and
compare the procedures and results to commercial-
ly available PCS immunoassay kits.
The results of the work brought out several areas
of opportunity for test improvement. An obvious
one would be to expand the search for matrices
(TLC plates, membranes, and filter papers) which
give an optimum balance between acceptable
blanks and enhancement of photosensitization.
Another opportunity is to search for photocatalysts
which speed up dechlorination of PCBs but do not
sensitize reduction of Ag+. Also, a detailed exami-
nation of photographic chemistry including color
photography may identify opportunities for
enhanced sensitivity and selectivity. The PCB
visualization relates to photography. The presence
of PCB in a solution may drastically alter the rate
of image development using commercially avail-
able film or photographic paper.
The use of SPE membranes can be expanded by
incorporating indicator molecules in the matrix.
The membrane could serve to both extract and
detect pollutants either in water or in air (Figure 7).
Preliminary experiments with tetracyanoethylene
(an electron acceptor) in C-18 Empore™, SPE
membranes, led to the appearance of color with
toluene. PCBs were not tested.
As with all field screening methods, laboratory
analyses need to be performed to confirm test
results consistent with previously set data quality
objectives.
PCB Contaminated Water
Suspected high PCB concentrations
Suspected low PCB concentrations
Use filter paper
• Dipstick mode
• Place drops of solution
directly on substrate
Use SPE membrane
• Dipstick mode with standing, or
• Fitterthrough membrane
Spray substrate with visualization reagent
Look for color
Compare to color chart for concentration level
Figure 5. Approaches for Sample Collection and Subsequent Detection of PCBs in Water.
19
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COST GC/MS > Immunoassay >|AgNO3/UV |
TIME GC/MS > Immunoassay ~|AgNO3/UV |
SELECTIVITY [GC/MS|> Immunoassay > AgNOs/UV
SENSITIVITY IOC/MS ~ Immunoassay > AgNO3/UV
SIMPLICITY [AgNO3/UV|> Immunoassay > GC/MS
Rgure 6. Comparison of Methods for PCBs.
USE OF SOLID PHASE
EXTRACTION MEMBRANES
PROBE
Octadecyl groups (C-18)
or other molecules
attached to silica
Sorb indicator molecules
into the solid phase
Allow analytas to sorb into
the solid phase and detect
with external probe or by eye
Rgura 7. An Approach for Sample Collection and Detection.
The research focused on concept validation and
technique optimization. The combination of SPE
or filter papers in a dipstick mode followed by
visualization of sorbed PCBs on the SPE or fil-
ter tabs using AgNO3 does seem very attractive
for field screening.
20
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SECTION 7
SUMMARY AND CONCLUSIONS
The objective of this study was to develop a sim-
ple, inexpensive, and rapid procedure which could
be used in field screening for PCBs in water. There
was special interest in developing a test in the pres-
ence of 1-3% by weight of surfactants in order to
follow the progress of remediating soil contaminat-
ed with PCBs by washing the soil with surfactant
solution. A test was developed based on forming
Ag+ complexes of PCBs with AgNO3 followed by
UV irradiation to form Ag metal. The appearance
of color (gray to brown depending on the PCB con-
centration) was used to signal the presence of PCB.
This is a visual test. Instruments are not required.
The test color can be compared to standard color
charts to give an estimate of the PCB level. In
addition to soil remediation monitoring, potential
applications include well monitoring, wellhead
protection monitoring, post-closure monitoring,
and rapid laboratory screening. For applications
related to soil remediation, it was found that filter
papers or SPE membranes could be used in a dip-
stick mode by spraying with methanolic AgNO3
and irradiation with 254 nm light from a hand
portable UV light. The detection range was 1.0-
500 ppm (or higher) in the presence of 3% Renex
KB orNeodol (R) 1-7; these are surfactants that are
currently being used for PCB soil remediation. A
detection limit of 0.5 ppm was found in solutions
containing mixtures of Neodol (R) 1-7 and Triton
X-100 (reduced) surfactants. Samples of 2%
Renex KB soil, washings containing 10 and 40 ppm
of PCB 1260 were screened. These were from
actual operations. The samples could easily be dif-
ferentiated but for unknown reasons, the test results
indicated that higher PCB concentration may have
been present. If the tests had been performed on
site, more information would have been available
and appropriate changes to the test and/or the color
interpretation most likely could have been made on
the spot. .
A number of factors were found to affect the
sensitivity of the visualization reaction, including
choice of the test matrix, nature of the surfactant
light wavelength and intensity, and presence of
possible interferences. Whatman 541 and 542 fil-
ter papers and C-18 Empore™ SPE membranes
were found to be the best matrices out of the 12
tested as surfaces for the visualization reaction.
The other materials served to photosensitize Ag+
reduction in the absence of PCBs. Neodol (R) 1-7
and Renex KB did not adversely affect the AgNO3-
UV visualization reaction. However, the four other
surfactants examined did, either giving a high
blank or increasing the detection limit. Use of 254
and 365 nm light and intense Nevada sunlight did
serve to facilitate reduction of Ag* in the visualiza-
tion reaction. However, use of 365 nm increased
the time needed for the photodegradation to occur.
On the other hand, intense sunlight resulted in the
Ag+ used on the blanks being reduced to Ag metal
in a relatively short time.
As expected, Cl~ was found to interfere in the
visualization reaction. The sensitivity was found to
be 1 ppm in the absence of surfactants. The colors
matched closely those obtained using PCBs at
equivalent ppm poncentration. The interference
was eliminated by adding a few granules or a mem-
brane tab of an anion exchange resin to the test
solution. However, it appears that the resin also
sorbs PCBs to some extent. The PCB detection
limit was raised to 10 ppm from 1 ppm. It is
judged that the limit can be lowered back to 1 ppm
with optimization of the amount of resin used. One
of the major interferences that might be expected in
ground water in the vicinity of high organic content
soil is humic acid. However, the interference is
negligible even at 1000 ppm. Also, humic acid did
not interfere with the PCB test. Several organic
compounds including biphenyl showed a light pink
color. However, since pink colors were not
observed with PCBs, these are not considered to be
serious interferences. Nevertheless, it is clear that
many aromatic and aliphatic compounds contain-
ing halogen (Cl or Br) may interfere. Volatile
21
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organic compounds such as CHC13, CC14,
C12CHCHC12, and CHC12 were not found to
interfere. In field screening scenarios, the sites
have already been characterized and the pollutants
are known. In remediation processes, the target
compounds are known as well. If there are a num-
ber of orgaohalogen pollutants, the AgNO3-UV
procedure can serve as a class test.
The potential of exploiting the results for a PCB
field screening test is judged to be high. The infor-
mation which has been gathered can be used as a
basis to further improve the PCB test and to devel-
op new field screening methods for other pollu-
tants. A promising area for further research is the
use of a catalyst for the dechlorination of PCBs
(and other organohalogen compounds) which does
not photosensitize Ag+ reduction. Further test
development in the short term could benefit from a
search for test matrices (TLC plates, membranes,
and filter papers) which give an optimum balance
between acceptable blanks and enhancement of
photosensitization. Also, a detailed examination of
photographic chemistry, including color photogra-
phy, may identify opportunities for enhanced sen-
sitivity and selectivity. The use of indicators pre-
sorbed in SPE membranes that can both extract and
detect pollutants in either water or air seems to be
a promising area to explore as well.
22
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J&U.S. GOVERNMENT PUNTING OFFICE: MM - «5MO6/002M
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