DIOXIN 2003 BOSTON SESSION SUMMARY REPORT Rapid Screening Methods Keith Worrall

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DIOXIN 2003 BOSTONSESSION SUMMARY REPORTRapid
Screening MethodsKeith Worrall Takeshi Nakano
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This session is comprised of approximately 19
presentations covering a variety of screening
methods for POPs.
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The session is divided in two parts 7 oral
presentations 12 poster format presentations.
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The session covers a diverse range of possible
screening methods, developed by colleagues from a
wide range of nationalities.
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Presenters are from Australia, Japan, United
Kingdom, Norway, Spain, Sweden, USA, Netherlands
and Hong Kong will participate in the session.
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For a considerable amount of time, High
Resolution GC High Resolution Mass Spectrometry
(HRGC-HRMS) methods have been the legislative and
accepted methods for the determination of
Dioxins, Furans and similar compounds in the
analytical laboratory.
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Whilst very accurate, these methods can be
time consuming and costly. The aim of this
session is to present methods that are being
proposed for the rapid screening of a wide
variety of matrices.
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There are a number of possible methods of
screening, in this session the emphasis is split
between bioassay monitoring, instrumental
methods and bio-monitoring.
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In the first of the Oral presentations, Leeuwen
and colleagues report on the validation of a wide
range of screening methods, with good accuracy
and repeatability obtained.
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Anderson and colleagues have worked on a
comparison of a rapid biological screening method
(EPA 4425) and chemical analytical methods.
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In a study concentrating upon ash, exhaust gas
and soil samples, they have concluded that the
comprehensive screening of a site using method
EPA 4425,
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followed by confirmation analysis of 10-20 of
the samples by HRGC-HRMS methods presents the
possibility for substantial project savings for a
large site.
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This work is complemented nicely by the work of
Leeder and colleagues, who present their work
looking at the applicability of EPA method 4025
for dioxin site assessment.
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The conclusions are that the method does provide
an effective approach to the assessment of sewage
treatment plants, being low cost, and having
improved turnaround times when compared with EPA
method 8290.
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Kobayashi and colleagues present an evaluation of
an ah-immunoassay screening method for PCDD/Fs
and dioxinlike compounds.
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The assay employs an efficient clean-up method
to remove possible interfering compounds such as
PAHs, which results in good correlation with
HRGC-HRMS techniques.
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The range of sample matrices covered offers a
useful tool for routine environmental screening.
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Nishi and colleagues have developed an
immunochromatographic test highly specific for
PCBs, allowing possible results to be obtained at
the point of sampling.
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Rivera and colleagues have studied the use of
mosses as bio-monitors. The properties of mosses
make them a suitable substrate for monitoring,
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as any contamination present will not be taken
from the substrate on which they grow, or
transferred to internal tissues.
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The conclusions demonstrate that the congener
profiles are maintained following deposition on
the moss, indicating that no metabolic or
transfer effects occur within the organism.
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Ohno and colleagues are presenting an enzyme
linked immunoassay (ELISA) technique that shows
high selectivity to 3 out of the 4 non-ortho
PCBs.
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The assay demonstrates virtually no reactivity to
other PCBs, PCDDs or PCDFs, providing a rapid and
specific method for the mass screening of
environmental samples, prior to confirmatory
analysis of high concentration samples.
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The final Oral presentation is by Engwall and
colleagues, and reports their findings from an
international intercalibration study of
dioxin-like compounds in cod liver using
bioassays.
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Intercalibration studies are one of the most
effective methods for evaluating the accuracy of
methods, in this case covering a number of
different bioassay methods.
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The study showed that a good percentage of the
participating laboratories gave values within
60-106 of the true value, indicating a good
degree of accuracy and showing good agreement
with chemical analysis by HRGC-HRMS.
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The authors also point at possible problems with
interfering compounds that can elevate the
determined TEQ, and also suggest work to be
performed to reduce the risk of false negatives.
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A large amount of the presented work in the
session looks into the application of various
immunoassay and bioassay methods as a tool for
the rapid screening of samples for PCDD/Fs and
PCBs.
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The methods work for a variety of different
matrices, for example human blood (Usuki),
flyash (Miyata, Matsuyama), PCB oil (Takigami)
environmental samples (Fujihara, Kobayashi).
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Most of the methods employ some specific clean-up
practices to remove compounds such as PAHs, and
other Ah antagonists, which can result in high
determined values when compared with HRGC-HRMS
methods or reference values.
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In contrast the work of Nording and colleagues
focuses on the bio-analysis of PAHs in soils, and
has produced a method recommended for
semi-quantitative analysis of PAHs.
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The method is far simpler to implement in the
field and the authors view is that this far
outweighs the lower accuracy as a tool for rapid
field screening.
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Ikeda and colleagues present some work
complementary to that presented by Rivera, where
Blue Mussels are utilized as bio markers to
monitor the levels of pollution across a wide
range of estuaries, beaches, canals and offshore.
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High levels detected in Blue Mussels corresponded
well with areas known to be affected by high
discharges of PCDD/Fs.
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C.S. NG and W.C. Chung have taken a slightly
different approach to speeding up analysis by
producing a simplified extraction and clean-up
method for application in foodstuff samples.
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Given the relatively complex nature of foodstuff
samples, the determined concentrations and good
recoveries presented
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an effective method has been produced which
accounting for the 1-2 days saved during clean-up
could increase sample turnover and reduce
turnaround times significantly.
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An instrumental approach to screening has been
taken by Worrall and colleagues, with the
development of a GC-MS/MS method, allowing
profiles of congeners to be detected and
reported, giving the possibility of the
finger-print of a source to determined.
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Borgen and colleagues have developed a method in
which a number of challenges due to the
complexity of the analytes needed to be overcome.
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Screening a number of areas in the south of
Norway for chlorinated paraffins, compounds for
which there are several thousand components in a
single commercial mixture.
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Analysis by electron capture negative-ion
ionisation gives greater selectivity allowing a
survey to be conducted.