DIOXIN 2003 BOSTONSESSION SUMMARY REPORT

Rapid Screening Methods

Keith Worrall & Takeshi Nakano

This session is comprised of approximately 19 presentations covering a variety of screening

methods for POPs.

The session is divided in two parts;

7 oral presentations

12 poster format presentations.

The session covers a diverse range of possible screening

methods, developed by colleagues from a wide range

of nationalities.

Presenters are from Australia, Japan, United Kingdom, Norway, Spain, Sweden, USA, Netherlands and Hong Kong will parti

cipate in the session.

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.

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.

There are a number of possible methods of screening, in this session the emphasis is split bet

ween bioassay monitoring, instrumen

tal methods and bio-monitoring.

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 re

peatability obtained.

Anderson and colleagues have worked on a comparison of a rapid biological screening method (EPA 4425) and chemical analy

tical methods.

In a study concentrating upon ash, exhaust gas and soil sampl

es, they have concluded that the comprehensive screening of a si

te using method EPA 4425,

followed by confirmation analysis of 10-20% of the samples by HRGC-HRMS methods presents the possibility for substantial project s

avings for a large site.

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 a

ssessment.

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.

Kobayashi and colleagues present an evaluation of an ah-immunoassay® screening method for PCDD/Fs and dioxinlike

compounds.

The assay employs an efficient clean-up method to remove possible interfering compounds such as PAHs, which results in good correlation with HRG

C-HRMS techniques.

The range of sample matrices covered offers a useful tool for routine environmental scree

ning.

Nishi and colleagues have developed an immunochromatographic test highly specific for PCBs, allowing possible results to be obtained at the poin

t of sampling.

Rivera and colleagues have studied the use of mosses as bi

o-monitors. The properties of mosses make them a suitable substrate for

monitoring,

as any contamination present will not be taken from the substrate on which they grow, or tra

nsferred to internal tissues.

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.

Ohno and colleagues are presenting an enzyme linked immunoassay (ELISA) technique that shows high selectivity to 3 out of the 4 non-ortho PCB

s.

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 concentrati

on samples.

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 usi

ng bioassays.

Intercalibration studies are one of the most effective methods for evaluating the accuracy of methods, in this case covering a number of different bioass

ay methods.

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 H

RGC-HRMS.

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 negat

ives.

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 PC

Bs.

The methods work for a variety of different matrices, for example human blood (Usuki), flyash (Miyata, Matsuyama), PCB oil (Takigami) environmental samples (Fujihara, Kobayashi).

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 r

eference values.

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-quantitativ

e analysis of PAHs.

The method is far simpler to implement in the field and the authors view is that this far outweighs the lower accuracy as a to

ol for rapid field screening.

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 offshor

e.

High levels detected in Blue Mussels corresponded well with areas known to be affected by high discharges of PCDD/F’s.

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.

Given the relatively complex nature of foodstuff samples, the determined concentrations and

good recoveries presented

an effective method has been produced which accounting for the 1-2 days saved during clean-up could increase sample turnover and reduce turnaround ti

mes significantly.

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-prin

t’ of a source to determined.

Borgen and colleagues have developed a method in which a number of challenges due to the complexity of the analytes neede

d to be overcome.

Screening a number of areas in the south of Norway for chlorinated paraffin’s, compounds for which there are several thousand components in a single commercial mixtur

e.

Analysis by electron capture negative-ion ionisation gives greater selectivity allowing a surve

y to be conducted.