United States
               Environmental Protection
               Agency
 Environmental Monitoring
 Systems Laboratory
 Las Vegas, NV 89193-3478
               Research and Development
EPA/540/SR-94/519 December 1994
EPA      Project  Summary
               A Field Screening Method  for
               Polychlorinated Biphenyl
               Compounds  in  Water

               Shen Lin, Edward J. Poziomek, and William H. Engelmann
                 The U.S. Environmental Protection
               Agency (EPA) has been exploring the
               complexation of silver ions with cer-
               tain organic pollutants as part of  a
               search for alternative low-cost, rapid
               field screening methods. The effort has
               resulted in a rapid, easy, and  inexpen-
               sive procedure for determining poly-
               chlorinated biphenyls (PCBs)  in water.
                 Based on previous testing of samples
               by General Electric Corporate Research
               and Development, a cosponsor of this
               project, there was a special interest in
               developing a field-screening procedure
               of PCB aqueous extracts performed
               from a current soil remediation proce-
               dure in which the extractant contained
               1-3% surfactant by weight to  enhance
               solubility of  PCBs.  A  test was devel-
               oped, based  on forming complexes of
               PCBs with silver ions, which  was fol-
               lowed by ultraviolet (UV) irradiation to
               yield metallic silver. The appearance of
               a  gray-to-brown color, depending on
               PCB concentration, was used to signal
               the presence of PCBs. This method
               allows the test color to  be directly com-
               pared with color charts to estimate the
               PCB concentration  without the need
               for instrumentation. In  addition to soil
               remediation monitoring, potential ap-
               plications include  well monitoring,
               wellhead protection monitoring, post-
               closure monitoring, and rapid labora-
               tory screening.
                 For soil remediation monitoring, it
               was found that several varieties of fil-
               ter paper or solid  phase extraction
               (SPE) membranes could be used in a
               dipstick mode, followed by spraying
               with methanolic silver  nitrate  solution
and irradiation with 254 nm light from a
hand-held UV lamp to provide a color
spot test. The detection range was 1-
500 ppm in the presence of either 3%
Renex KB™* or Neodol (R) 1-7™, sur-
factants currently being examined in
soil remediation.
  This Project Summary was developed
by EPA's Environmental Monitoring Sys-
tems Laboratory, Las Vegas, NV, to an-
nounce  key findings of the research
project that is fully documented In a
separate report of the same title (see
Project Report ordering information at
back).


Introduction
  The overall challenge of field screening
involves dealing with numerous pollutants
within many classes (organic, inorganic,
biomarker, and radionuclide), across vari-
ous media, and in complex mixtures. The
detection limits of field methods are not
always as low nor as reliable and accu-
rate as laboratory methods. However, the
data quality objectives in a particular sce-
nario may allow field methods to  be used.
For example, less accurate methods can
be used to screen environmental samples
prior to confirmatory laboratory analyses.
A cost advantage results by reducing the
number of required laboratory analyses.
  Field screening  methods may provide
rapid  performance at low cost  to allow
determination of whether a parameter of
interest is present or absent, above or
' Mention of trade names or commercial products does
 not constitute endorsement or recommendation for
                                                               Printed on Recycled Paper

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below a predetermined threshold at a given
site, or at a concentration within a prede-
termined range of interest. Field screen-
ing methods can also be used in the field
to identify the nature  and extent of con-
tamination at individual sites. A few field
screening methods are currently available
and additional ones are being developed.
The most mature methods are based on
gas chromatography  and X-ray fluores-
cence. One of the clear trends is to minia-
turize. Methods  that are  still  in various
stages of development include the use of
fiber  optic  sensors  and  chemical
microsensors, such as piezoelectric quartz
microbalances and surface acoustic wave
probes. The technologies developed as
field screening methods  conform to the
monitoring  and  measurement needs_of
many EPA programs.
  The need for field screening of ground
water relates  to  protecting  public  water
supply  wells  and well  fields,  following
remediation efforts, and post-closure moni-
toring of hazardous waste disposal sites,
as examples. Ground water contains many
natural constituents, with the various spe-
cies and concentrations depending on fac-
tors such as the specific  geochemical
environment  and the source  of ground
water. The major anions  that are usually
analyzed for general water quality include
bicarbonate, chloride,  nitrate, and sulfate.
Other general indicators include electrical
conductivity, temperature, pH, dissolved
oxygen, biochemical oxygen  demand,
chemical oxygen demand, total organic
carbon, oxidation-reduction potential, total
suspended solids, total dissolved solids,
and turbidity.
  The present research, described in the
full report (based on  the  Master of  Sci-
ence thesis of Shen Lin, first author of this
project summary), describes the develop-
ment of a new concept for field screening
that emphasizes speed, ease of applica-
tion, tow cost, and in situ water monitoring
for following PCB soil  remediation.
  The central idea brought forward in this
research was to form silver complexes
with RGBs directly in the environmental
samples and to display their comparative
concentration levels through rapid devel-
opment of  a gray-to-brown  coloration of
finely-divided silver on SPE or filter paper
substrates using a brief UV irradiation or
sunlight. In other words, this new process
combines development of a photo-gray or
photo-brown  coloration on various  sub-
strates and relates the color or shading to
a color chart produced from known silver
concentrations, and therefore PCB levels,
in the environmental sample.
Approach

  A preliminary step was to devise a con-
venient method for extracting and  con-
centrating PCBs from  the aqueous
environmental samples. This was followed
by the development of a chemical reac-
tion or molecular association effect that
could provide a visual signal for the pres-
ence of PCBs.
  While liquid-liquid extraction can be used
to separate  organic  components from
aqueous  solutions, the process is slow,
labor  intensive,  and  requires large vol-
umes of  solvents. The latter  creates an-
other potential pollution problem.  With
rising waste  disposal  costs,  laboratory
technologists  today are turning to the use
of SPE membranes._to,«adso.rb anoLcon.-_
centrate  the organic  compounds directly
from the  water sample, avoiding the need
for organic solvents. Filtering the solution
through a SPE  disk concentrates the sol-
ute through adsorption on the silicate ma-
trix.  Their specific  adsorbing power is
generally sufficient to allow SPE material
to be cut into small tabs and used in a
"dipstick" mode with the water sample.
  The SPE disk or tab, exposed to PCBs
in solution,  generally shows no color
change (other than possibly some colora-
tion from  suspended matter in the sample).
The  early literature (1970s)  of thin-layer
chromatography provided insight into pos-
sible visualization agents for the adsorbed
PCBs on the SPE disks or tabs: PCBs
can be reacted with silver nitrate to yield
silver-PCB complexes.  These complexes
are not  stable  and  UV  irradiation  from
sunlight  or other source  rapidly  breaks
down the silver-organic complex. Free sil-
ver, in finely divided form, appears on the
substrate as  a gray-to-brown coloration.
Based on  the  literature  references, the
decision  was  made to exploit this reaction
and optimize  the performance to provide
adaptation for environmental monitoring.
It was also found in the early experiments
that  if the PCB concentration  is  high
enough, preconcentration, using SPE tech-
niques, is not necessary.  Filter paper can
be spotted with this test solution directly,
or a filter paper tab can be dipped into the
solution.

Experimental
  Two test  formats  were  chosen for
sample collection. One used small tabs,
cut from  SPE material or filter paper, and
exposure to the water samples in a "dip-
stick" manner for several minutes. In a
second  test  format,  test solution was
placed dropwise directly  on the  SPE or
filter paper tabs. Other test formats, such
as filtering the test solutions through the
SPE or filter paper disks, could have been
used but at a loss of ease for use in the
field. It was decided to place developmen-
tal emphasis  on the dipstick test format
because of its simplicity and retained ef-
fectiveness.
  When PCBs contaminate soil, they raise
a specific environmental challenge in that
they become firmly bound to the soil ma-
trix because of their high molecular weight
and low water solubility.
  However, the presence of  surfactants
may increase  the solubility  of  PCBs in
water.  The use of  surfactants  such as
Renex™ and Neodol (R) 1-7™ (both non-
ionic compounds) is being examined by
others- Jn ^PCB ., so.il,-washing ... and.
remediation processes.
  The  development of a  PCB  detection
test in  the presence of these surfactants
would serve to provide a very useful moni-
toring scheme to follow the soil-washing
procedure. Surfactants such as  these in-
crease the solubility of PCBs to the 500
ppm range. At  high concentration levels,
the use of SPE techniques would not seem
necessary. However,  experiments using
SPE membranes to concentrate PCBs fur-
ther  were included to  increase the appli-
cability of the test to other field screening
scenarios.
  Test solutions of  the  PCBs were pre-
pared in methanol and diluted with deion-
ized water, either with or without surfactant.
Control solutions also contained  surfac-
tants, if used in the tests.
  The  SPE tabs (1x1  cm) were condi-
tioned  by dipping into methanol just be-
fore  use; this  allowed them to be  wet
easily by the aqueous  test solutions. Tabs
were either suspended in the various PCB
test  solutions for 30  minutes  or  dipped
and  quickly removed. They were  then
sprayed  with  0.059 M silver nitrate in
methanol. Irradiation followed with a UV
lamp (254 nm)  for 1-3 minutes. The UV
lamp was held  1.5 cm from the tabs. The
development of color,  relative to a control
tab after 1 minute, signaled the  presence
of PCBs.
  Filter paper tabs (1 x 1 cm) were dipped
into  the  PCB  test  solution,  removed,
sprayed  with  0.059 M silver nitrate in
methanol, and  exposed for 3 minutes in
the same manner as above. For simplicity
in field testing and to avoid the need for
instrumental readings, Ameritone™ paint
color chips were used as standards for
defining the exact color and  intensity. All
results were based  on at least  duplicate
runs, with some being taken in triplicate.

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Results and Discussion

  Tests with SPE membranes (1-hour pas-
sive immersion), followed by silver nitrate
visualization, detected PCBs at the 0.5-
1.0 ppm level in the absence of surfac-
tant; at 22-24  hours  there was no
improvement, but shortening the exposure
time to 30 minutes raised the detection
level to 5  ppm. SPE membranes were
also used to extract PCBs from aqueous
solution containing surfactant by exposing
the tabs for 30 minutes. The detection
limit varied  from 0.5-5  ppm, depending
on the type of PCB.
  Tests with filter paper tabs  (Whatman
541™)  involved dipping and  immediate
removal, spraying with silver nitrate solu-
tion,, and  irradiating, with., UV Jight. ,The^
PCB  solutions  contained either Renex
KB™ or Neodol 1-7™  surfactants. The
results show that PCBs can  be readily
detected on Whatman 541 filter paper in
the presence of these  surfactants. The
colors differed somewhat from  SPE tabs,
depending on the PCB and surfactant type.
  At the high PCB level of 500 ppm, the
test colors were not gray but brown with a
trace of gray. The control tabs showed
very little color even though the solutions
contained 3% surfactant.
  It is also interesting to  note that dipping
the Whatman 541  filter  paper tabs and
quickly removing them is about as sensi-
tive as the technique in  which SPE tabs
(in the presence of surfactant) were al-
lowed to stand for 30 minutes. It is sug-
gested that the  surfactant may  be
competing with  the PCBs for adsorption
onto the SPE medium.
  As for possible interferences, it was ex-
pected that chloride ions would interfere
 in the visualization reaction since silver
 chloride, which is extremely sensitive to
 light, would be formed. The sensitivity for
 chloride ion was found to be 1 ppm in the
 absence of surfactants;  no color was ob-
 served with 0.5 ppm. Positive tests were
 found with PCBs at 0.5 ppm, but the higher
 sensitivity is understandable since equiva-
 lent chloride would be available from the
 PCBs. The colors matched closely those
 obtained using PCBs, i.e., very light gray
 at 1 ppm and brown  at the  highest con-
 centrations, i.e., 1000 ppm  chloride  ion.
 The chloride  ion  interference could be
 eliminated  by adding a few granules of
 anion exchange resin (AG 1-X2™), lightly
 agitating, and continuing with the test in
 the usual manner. Results remained nega-
tive, up-to 1000 ppm chloride ion.  ._ ...   ,

 Summary and Conclusions
  The objective was to develop a simple,
 alternative,  and  inexpensive test proce-
 dure for field  screening PCBs in water.
 There was a special interest to determine
 whether the test  would  work well  in the
 presence of 1-3% surfactants in  order to
 follow  the progress  of washing or
 remediation of soils  contaminated with
 PCBs.
  A visual test requiring no instruments
 was developed based on forming silver
 ion complexes of PCBs from silver ni-
 trate, followed by brief UV irradiation to
 form finely divided silver metal. The lat-
 ter appeared as a gray or brown colora-
 tion, depending on PCB  concentration.
 The test color can be easily compared
 to standard color charts  or paint chips
 to give an  estimate of the PCB level. In
addition to soil-remediation monitoring,
potential applications include well moni-
toring,  wellhead protection monitoring,
post-closure  monitoring, and rapid
screening of laboratory samples.
  A number of factors were found to af-
fect the sensitivity of the visualization re-
action,  including choice of test  matrix,
nature of the surfactant, wavelength and
intensity of the light, and presence of pos-
sible  interferences.  These are described
in more detail in the full report.
  As expected, chloride ion was found to
interfere. The chloride sensitivity was found
to be 1 ppm in the presence  of  surfac-
tants. The colors closely matched those
obtained using PCBs. However, the chlo-
ride ion interference was eliminated by
adding  a few granules  of  an  anion ex-
change resin to the test solution.
  The potential  of exploiting the  results
for a PCB field screening test is judged to
be  high. The findings can be used as a
basis to further improve the PCB detec-
tion test and to develop new field screen-
ing  methods for other pollutants.
  A promising area for further research is
the use of a catalyst for the dechlorination
of PCBs (and other organohalogen com-
pounds) that do not photosensitize silver
ion  reduction.
  Also, a detailed  examination  of the
chemistry of photography, including color
photography,  may identify other opportu-
nities for enhanced sensitivity and selec-
tivity. The use of indicators presorbed onto
SPE membranes, which can both  extract
and detect pollutants in either water or air,
appears to be  a promising area  to ex-
plore.

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 Shen Lin and Edward J. Poziomek are with University of Nevada, Las Vegas, NV
   89154-4009. The EPA author, William H. Engelmann, (also the EPA Project
   Officer, see below) is with the Environmental Monitoring Systems Laboratory,
   Las Vegas, NV 89193-3478.
 The complete report, entitled "A  Field Screening Method for Polychlorinated
   B'phenyl Compounds in Water," (Order No. PB95-129078; Cost: $ 17.50, subject
   to change) will be available only from
         National Technical Information Service
         5285 Port Royal Road
         Springfield, VA 22161
         Telephone: 703-487-4650
 The EPA Project Officer can be contacted at
         Environmental Monitoring Systems Laboratory
         U.S. Environmental Protection Agency
         Las Vegas, NV 89193-3478
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268

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