Analytical

methods

for

PCBs

and

organochlorine

pesticides

in

environmental

monitoring

and

surveillance

a

critical

appraisal

Analytical

methods

for

the

analysis

of

polychlorinated

biphenyls

-LRB-

PCBs

-RRB-

and

organochlorine

pesticides

-LRB-

OCPs

-RRB-

are

widely

available

and

are

the

result

of

a

vast

amount

of

environmental

analytical

method

development

and

research

on

persistent

organic

pollutants

-LRB-

POPs

-RRB-

over

the

past

years

This

review

summarizes

procedures

and

examines

new

approaches

for

extraction

isolation

identification

and

quantification

of

individual

congeners/isomers

of

the

PCBs

and

OCPs

Critical

to

the

successful

application

of

this

methodology

is

the

collection

preparation

and

storage

of

samples

as

well

as

specific

quality

control

and

reporting

criteria

and

therefore

these

are

also

discussed

With

the

signing

of

the

Stockholm

convention

on

POPs

and

the

development

of

global

monitoring

programs

there

is

an

increased

need

for

laboratories

in

developing

countries

to

determine

PCBs

and

OCPs

Thus

while

this

review

attempts

to

summarize

the

current

best

practices

for

analysis

of

PCBs

and

OCPs

a

major

focus

is

the

need

for

low-cost

methods

that

can

be

easily

implemented

in

developing

countries

A

performance

based

process

is

described

whereby

individual

laboratories

can

adapt

methods

best

suited

to

their

situations

Access

to

modern

capillary

gas

chromatography

-LRB-

GC

-RRB-

equipment

with

either

electron

capture

or

low-resolution

mass

spectrometry

-LRB-

MS

-RRB-

detection

to

separate

and

quantify

OCP/PCBs

is

essential

However

screening

of

samples

especially

in

areas

of

known

use

of

OCPs

or

PCBs

could

be

accomplished

with

bioanalytical

methods

such

as

specific

commercially

available

enzyme-linked

immunoabsorbent

assays

and

thus

this

topic

is

also

reviewed

New

analytical

techniques

such

two-dimensional

GC

-LRB-

-RRB-

and

fast

GC

using

GC

ECD

may

be

well-suited

for

broader

use

in

routine

PCB/OCP

analysis

in

the

near

future

given

their

relatively

low

costs

and

ability

to

provide

high-resolution

separations

of

PCB/OCPs

Procedures

with

low

environmental

impact

-LRB-

SPME

microscale

low

solvent

use

etc.

-RRB-

are

increasingly

being

used

and

may

be

particularly

suited

to

developing

countries

Introduction

Scope

of

the

review

Polychlorinated

biphenyls

-LRB-

PCBs

-RRB-

and

organochlorine

pesticides

-LRB-

OCPs

aldrin

chlordane

DDT

dieldrin

endrin

heptachlor

mirex

toxaphene

hexachlorobenzene

-LRB-

HCB

-RRB-

-RRB-

constitute

ten

of

the

twelve

chemical

substances/groups

currently

defined

under

the

Stockholm

Convention

on

Persistent

Organic

Pollutants

-LRB-

POPs

-RRB-

While

bans

and

phase-outs

of

these

chemicals

occurred

during

the

and

in

most

developed

countries

they

were

not

in

place

in

many

developing

countries

Article

of

the

Stockholm

Convention

requires

National

Implementation

Plans

-LRB-

NIPs

-RRB-

to

be

developed

by

signatory

countries

-LSB-

-RSB-

For

countries

where

PCBs

and

OCPs

are

still

in

use

or

loosely

regulated

the

NIPs

will

eventually

lead

to

the

phase-out

of

OCPs

for

agricultural

use

and

reduced

use

for

disease

vector

control

However

many

countries

will

be

faced

with

the

legacy

of

past

use

of

these

persistent

chemicals

Residues

in

soils

sediments

and

biota

will

pose

a

risk

for

wildlife

and

human

consumers

The

problems

of

destroying

existing

stockpiles

especially

of

OCPs

and

PCBs

in

electrical

equipment

as

well

as

preventing

migration

of

contaminants

from

storage

areas

will

need

to

be

solved

There

is

a

need

to

monitor

levels

and

trends

now

and

into

the

future

in

order

to

assess

compliance

with

the

POPs

Convention

within

each

country

as

well

as

on

a

regional

and

global

basis

Methodology

is

available

for

PCBs

and

OCPs

as

a

result

of

a

vast

amount

of

environmental

analytical

chemistry

research

and

development

over

the

past

to

years

However

the

establishment

of

an

analytical

laboratory

and

the

application

of

this

methodology

at

currently

acceptable

international

standards

is

a

relatively

expensive

undertaking

Furthermore

the

current

trend

to

use

isotope-labeled

analytical

standards

and

high-resolution

mass

spectrometry

for

routine

POPs

analysis

is

particularly

expensive

These

costs

limit

participation

of

scientists

in

developing

countries

and

this

is

clear

from

the

relative

lack

of

publications

and

information

on

POPs

from

countries

in

Africa

south

Asia

and

South/Central

America

Thus

this

review

will

summarize

the

best

practices

in

developed

countries

and

new

advances

in

PCB/OCP

analysis

while

bearing

in

mind

the

need

for

low-cost

methods

easily

implemented

in

developing

countries

This

review

will

also

mainly

focus

on

methodology

for

the

analysis

of

PCB/OCPs

in

biological

samples

-LRB-

fish

aquatic

and

terrestrial

mammals

and

birds

-RRB-

as

well

as

soils

sediment

and

passive

samplers

such

as

semipermeable

membrane

devices

-LRB-

SPMDs

-RRB-

These

matrices

and

environmental

compartments

have

higher

concentrations

of

PCBs

and

most

OCPs

than

water

or

air

making

them

more

suitable

for

routine

monitoring

and

more

relevant

in

the

context

of

exposure

of

humans

and

wildlife

Milk

and

blood

are

important

matrices

for

POPs

monitoring

in

humans

and

in

the

case

of

blood

are

increasingly

used

in

programs

involving

live-captured

marine

mammals

and

birds

Thus

analytical

methods

for

milk

and

blood

are

briefly

considered

here

The

advantages

and

disadvantages

of

various

bioindicator

species

are

discussed

in

detail

by

Tanabe

and

Subramanian

-LSB-

-RSB-

Substances

to

be

analyzed

PCBs

-LRB-

except

non-ortho-substituted

congeners

no-PCB

-RRB-

and

OCPs

can

be

considered

together

because

they

are

extracted

and

analyzed

together

in

most

cases

as

discussed

below

In

practice

most

laboratories

determine

about

or

more

individual

PCB

congeners

and

individual

OCPs

and

their

metabolites

regardless

of

the

sample

matrix

Ongoing

POPs

monitoring

programs

vary

in

their

analyte

lists

For

example

the

Integrated

Atmospheric

Deposition

Network

-LRB-

IADN

-RRB-

in

the

Great

Lakes

region

of

North

America

includes

over

PCB

congeners

-LSB-

-RSB-

while

the

UNEP/World

Bank/GEF

project

on

Persistent

Organic

Pollutants

Food

Security

and

Indigenous

Peoples

in

Arctic

Russia

included

PCB

congeners

-LSB-

-RSB-

The

Arctic

Monitoring

and

Assessment

Program

recommended

ortho-substituted

PCBs

-LSB-

-RSB-

The

UNEP

Global

POPs

monitoring

workshop

categorized

individual

PCB/OCPs

as

essential

and

recommended

taking

into

consideration

the

need

for

various

levels

of

analytical

capacity

building

in

developing

countries

in

order

to

conduct

the

monitoring

-LRB-

Electronic

Supplementary

Material

Table

-RRB-

-LSB-

-RSB-

For

PCBs

a

minimum

of

seven

PCBs

-LRB-

and

-RRB-

were

regarded

as

essential

for

routine

monitoring

of

fish

and

food

products

around

the

world

Using

only

seven

congeners

severely

underestimates

total

PCB

concentrations

in

some

matrices

particularly

in

abiotic

samples

such

as

air

soil

and

sediment

On

the

other

hand

these

seven

are

robustly

determined

having

been

the

subject

of

numerous

interlab

comparisons

-LRB-

e.g.

QUASIMEME

-LSB-

-RSB-

-RRB-

UNEP

-LSB-

-RSB-

recommended

a

suite

of

ortho-substituted

congeners

for

more

comprehensive

monitoring

Toxaphene

and

chlordane

are

multicomponent

mixtures

and

analytical

standards

are

available

for

some

but

not

all

major

components

which

makes

them

the

most

difficult

to

analyze

among

the

eight

OCPs

on

the

POPs

list

Current

programs

in

Europe

are

determining

three

toxaphene

congeners

Parlar

-LRB-

P

-RRB-

and

and

interlaboratory

comparisons

have

shown

reasonable

agreement

for

these

congeners

among

laboratories

-LSB-

-RSB-

However

is

interfered

with

by

coeluting

chlorobornanes

in

some

matrices

and

can

vary

widely

in

its

instrumental

response

Furthermore

in

North

America

most

datasets

for

toxaphene

are

still

based

on

quantification

with

technical

toxaphene

which

yields

a

single

value

and

no

congener-specific

information

Capacity

for

determining

toxaphene

outside

of

the

USA

Canada

and

western

Europe

is

very

limited

judging

from

the

relatively

large

number

of

measurements

from

these

countries

and

the

dearth

of

measurements

elsewhere

The

situation

for

chlordane

is

better

because

analytical

standards

are

available

for

the

major

components

-LRB-

cis

and

trans-chlordane

cis

and

trans-nonachlor

heptachlor

-RRB-

Nevertheless

other

octachloro

and

nonachlorochlordane

components

are

important

-LSB-

-RSB-

and

are

often

found

in

top

predators

-LSB-

-RSB-

and

analysts

need

to

be

aware

of

possible

interferences

from

these

compounds

in

seabird

and

marine

mammal

extracts

The

chlorinated

insecticides

endosulfan

lindane

and

methoxychlor

are

also

candidates

for

inclusion

in

analytical

methods

where

impacts

of

OCPs

are

being

investigated

Global

use

of

these

insecticides

particularly

endosulfan

is

very

significant

-LSB-

-RSB-

These

current-use

pesticides

can

generally

be

isolated

and

quantified

along

with

other

OCPs

The

no-PCBs

need

to

be

considered

separately

because

their

analytical

methodology

is

normally

quite

different

from

that

used

for

ortho-substituted

PCBs

and

OCPs

-LRB-

see

Reiner

et

al.

-LSB-

-RSB-

in

this

issue

-RRB-

In

summary

the

minimum

number

of

PCB/OCPs

to

be

considered

will

vary

with

the

objectives

of

a

given

study

A

long

list

of

analytes

would

be

used

for

initial

surveys

where

no

information

was

available

Chemical

structures

and

physical

and

chemical

properties

of

selected

PCBs

and

OCPs

are

listed

in

Electronic

Supplementary

Material

Table

-LSB-

-RSB-

Analytical

standards

The

availability

of

accurate

analytical

standards

is

a

fundamental

requirement

of

an

analytical

program

designed

to

quantify

PCB/OCPs

Standards

are

available

from

commercial

chemical

supply

companies

as

well

as

from

agencies

involved

in

certification

of

reference

materials

e.g.

the

National

Institute

of

Standards

and

Technology

-LRB-

NIST

-RRB-

or

from

the

Bureau

Communautaire

de

Référence

-LRB-

BCR

-RRB-

via

the

Sigma-Aldrich

company

Interlaboratory

studies

have

shown

that

incorrect

analytical

standards

and

calibration

errors

can

be

a

major

source

of

error

in

POPs

analysis

-LSB-

-RSB-

These

authors

recommended

that

multilevel

calibration

at

levels

should

be

used

to

define

the

response

profile

that

calibration

solutions

should

be

checked

against

independent

solutions

either

from

another

reliable

laboratory

or

by

preparing

duplicate

solutions

and

that

calibrants

should

be

ampouled

-LRB-

in

sealed

glass

vials

-RRB-

for

long-term

storage

They

noted

that

refrigerator

storage

can

loosen

the

caps

on

screw-top

vials

Thus

storage

of

calibrant

solutions

in

this

manner

should

only

be

temporary

Quantification

of

PCBs

can

be

carried

out

using

two

approaches

by

Aroclor

mixture

or

individual

congener

standard

The

former

method

employs

a

standard

that

was

available

as

a

commercial

product

-LRB-

e.g.

Aroclor

used

in

transformer

oils

-RRB-

to

quantitate

the

congeners

contained

in

the

Aroclor

mixture

against

those

matching

in

the

sample

There

are

several

mixtures

available

with

varying

degrees

of

mean

chlorination

Percent

ratios

of

the

congeners

in

various

commercial

mixtures

have

been

reported

-LSB-

-RSB-

The

limitation

of

this

method

is

the

varying

congener

ratios

within

a

given

commercial

mixture

due

to

batch-to-batch

production

variability

which

in

turn

may

lead

to

congener

calculation

error

-LSB-

-RSB-

Also

a

significant

bias

resulting

in

an

overestimation

of

PCB

measurements

may

occur

if

the

PCB

pattern

in

the

sample

does

not

match

that

of

the

standards

Sather

et

al.

-LSB-

-RSB-

suggested

that

accurate

PCB

determinations

can

be

made

if

the

chromatographic

pattern

of

both

the

standards

and

the

samples

are

similar

However

if

the

pattern

differs

the

study

reported

a

bias

doubling

the

values

determined

by

the

individual

congener

standard

The

method

of

choice

is

congener

determination

using

standard

mixtures

comprising

composite

individual

congeners

added

at

known

quantities

which

were

purchased

individually

This

provides

an

improved

and

known

level

of

accuracy

not

possible

with

the

commercial

PCB

mixture

approach

-LSB-

-RSB-

Commonly

used

analytical

methods

for

PCB/OCP

monitoring

and

surveillance

Overview

Numerous

methods

have

been

published

over

the

past

years

related

to

specific

analytical

techniques

for

the

determination

of

PCBs

and

OCPs

in

food

and

environmental

matrices

Laboratory

standard

operating

procedures

-LRB-

SOPs

-RRB-

are

available

from

the

National

Environmental

Methods

Index

in

the

USA

-LRB-

which

includes

US

EPA

and

US

Geological

Survey

methods

-RRB-

-LRB-

-RRB-

and

the

Japan

Environment

Agency

-LRB-

-RRB-

the

National

Oceanographic

and

Atmospheric

Administration

in

the

USA

-LSB-

-RSB-

and

the

US

Food

and

Drug

Administration

-LSB-

-RSB-

Useful

information

may

also

be

available

from

the

International

Committee

for

Exploration

of

the

Sea

-LSB-

-RSB-

the

Oslo

Paris

Commission

-LSB-

-RSB-

-LRB-

-RRB-

the

Helsinki

Commission

-LRB-

HELCOM

-RRB-

-LRB-

-RRB-

the

International

Organization

for

Standardization

-LRB-

-RRB-

the

Association

of

Official

Analytical

Chemists

International

-LRB-

-RRB-

and

Gosstandart

of

the

Russian

Federation

-LRB-

-RRB-

Not

all

of

these

sources

provide

analytical

SOPs

for

all

environmental

media

Alternatively

numerous

books

are

available

that

summarize

methods

For

example

Keith

-LSB-

-RSB-

summarized

US

EPA

methods

for

PCBs

and

OCP

in

sediment

and

biological

materials

Wells

and

Hess

-LSB-

-RSB-

have

reviewed

and

recommended

methods

for

the

separation

isolation

and

recoveries

of

OCPs

and

PCBs

from

soils

sediment

and

biological

matrices

De

Boer

and

Law

-LSB-

-RSB-

provide

a

useful

overview

of

current

analytical

methodology

for

OCP/PCBs

The

UNEP

POPs

workshop

on

global

monitoring

-LRB-

UNEP

-RRB-

noted

that

given

the

broad

range

of

technical

expertise

for

analysis

of

PCBs

and

OCPs

as

evident

from

the

extensive

international

participation

in

interlaboratory

calibration

projects

for

these

compounds

no

single

detailed

step-by-step

analytical

method

can

be

recommended

Instead

laboratories

would

use

methods

best-suited

to

their

situation

and

take

part

in

international

interlaboratory

comparisons

to

verify

their

work

This

performance-based

approach

has

also

been

adopted

by

the

US

EPA

in

an

effort

to

introduce

flexibility

in

conducting

environmental

monitoring

This

approach

also

encourages

analytical

innovation

by

allowing

the

use

of

new

and

alternate

methods

provided

that

predetermined

performance

criteria

are

met

-LSB-

-RSB-

Sampling

Acquisition

of

suitably

representative

samples

is

fundamental

to

any

environmental

measurement

program

and

should

not

be

overlooked

Contamination

during

field

collection

can

occur

particularly

from

PCBs

in

electrical

equipment

and

building

products

-LRB-

e.g.

marine

paints

joint

sealants

-RRB-

-LSB-

-RSB-

or

due

to

the

ongoing

use

of

OCPs

Clean

techniques

need

to

be

adopted

such

as

the

use

of

special

clothing

and

disposable

gloves

for

sampling

sealed

shipping

containers

and

field

blanks

ICES

-LSB-

-RSB-

NOAA

-LSB-

-RSB-

and

OSPAR

-LSB-

-RSB-

provide

useful

guidelines

for

sampling

of

fish/crustaceans

mussels

and

sediment

respectively

Azcue

and

Mudroch

-LSB-

-RSB-

provide

a

detailed

overview

of

sampling

methods

for

lakes

and

river

sediments

Sample

containers

should

be

supplied

by

the

laboratory

and

checked

for

contamination

Appropriate

sample

containers

for

biological

tissue

that

is

to

be

analyzed

for

POPs

are

glass

jars

or

glass

vials

with

screw

caps

Screw

caps

should

be

lined

with

solvent-rinsed

aluminum

foil

or

Teflon

cap

inserts

Clear

polyethylene

bags

and

polypropylene

jars

are

also

appropriate

for

temporary

storage

but

may

not

be

suitable

for

long-term

storage

because

of

the

possibility

of

migration

of

plasticizers

-LRB-

such

as

phthalates

-RRB-

into

the

tissue

especially

for

samples

with

high

lipid

contents

Freezing

and

storage

of

multiple

small

samples

suitable

for

analysis

rather

than

larger

masses

is

recommended

to

avoid

multiple

freezing

and

thawing

of

tissue

-LSB-

-RSB-

and

to

reduce

sample

handling

which

in

turn

reduces

the

potential

for

contamination

Samples

can

be

wrapped

in

aluminum

foil

and

then

inserted

into

plastic

bags

Blood

samples

should

be

collected

in

ethylenediamine

tetraacetic

acid

-LRB-

EDTA

-RRB-

vials

or

vacutainers

centrifuged

and

the

plasma

transferred

to

vials

washed

with

hexane

Field

blanks

consisting

of

sample

containers

taken

to

the

lab

and

returned

with

other

samples

should

be

included

Air

sampling

for

POPs

is

normally

conducted

using

polyurethane

foam

-LRB-

PUF

-RRB-

or

XAD

resin

-LSB-

-RSB-

From

to

of

air

are

passed

through

the

sampling

medium

-LSB-

-RSB-

Sampling

media

are

then

transferred

to

clean

wide-mouthed

glass

jars

sealed

and

stored

at

°C

prior

to

extraction

Some

sampling

cartridges

can

be

sealed

and

transported

and

the

sampling

media

transferred

to

Soxhlet

or

pressurized

liquid

extraction

systems

in

a

clean

laboratory

environment

Water

sampling

is

particularly

prone

to

contamination

by

PCBs

due

to

ubiquitous

contamination

especially

on

older

ships

and

buildings

and

to

the

very

low

sample

concentrations

likely

to

be

encountered

-LSB-

-RSB-

US

EPA

analytical

methods

for

PCBs

in

water

assume

that

drinking

water

is

being

analyzed

-LSB-

-RSB-

and

do

not

place

much

emphasis

on

sampling

because

the

drinking

water

quality

guideline

is

ug/L

and

only

small

L

samples

need

to

be

collected

to

assess

compliance

Solid-phase

extraction

-LRB-

SPE

-RRB-

cartridges

have

been

widely

used

to

extract

relatively

small

volumes

-LRB-

L

-RRB-

for

OCP

analysis

-LSB-

-RSB-

For

sampling

of

natural

waters

where

PCB

concentrations

are

in

the

low

pg/L

range

much

larger

samples

are

required

For

example

Achman

et

al.

-LSB-

-RSB-

pumped

lake

water

-LRB-

L

-RRB-

directly

into

large-diameter

filters

-LRB-

μm

nominal

pore

size

-RRB-

and

then

through

resin

columns

Surrogate

standards

were

added

to

the

resin

column

prior

to

extraction

Similar

solid-phase

extraction

approaches

are

used

for

sampling

and

extracting

wet

precipitation

-LSB-

-RSB-

Another

large-volume

application

uses

liquid

liquid

extraction

in

a

continuous

flow

approach

-LSB-

-RSB-

This

involves

a

one

pass-through

extraction

unit

where

the

sample

is

metered

into

a

mixing

chamber

which

contains

a

solvent

-LRB-

i.e.

dichloromethane

-RRB-

and

flows

out

to

an

overflow

exit

The

drawback

to

this

method

is

the

significant

potential

for

contamination

due

to

exposure

to

the

surrounding

air

Petrick

et

al.

-LSB-

-RSB-

describe

an

in

situ

sampler

for

the

collection

of

very

large

volumes

-LRB-

L

-RRB-

of

seawater

on

polyurethane

foam

for

the

determination

of

PCBs

at

low

pg/L

concentrations

The

studies

by

Petrick

et

al.

-LSB-

-RSB-

and

Sobek

and

Gustafsson

-LSB-

-RSB-

illustrate

the

great

care

that

is

needed

to

properly

determine

PCBs

at

the

low

pg/L

level

-LRB-

femtograms/L

of

individual

congeners

-RRB-

that

are

found

in

ocean

waters

SPMDs

offer

potential

for

relatively

inexpensive

sampling

of

water

and

air

for

POPs

and

potential

for

broad

geographic

coverage

-LSB-

-RSB-

For

water

sampling

lipid-based

SPMDs

-LRB-

consisting

of

triolein

inside

polyethylene

tubing

-RRB-

have

generally

been

used

to

estimate

bioavailable

water

concentrations

SPMD

use

in

the

aquatic

environment

has

been

validated

in

a

series

of

studies

-LSB-

-RSB-

The

use

of

performance

reference

compounds

-LRB-

PRCs

-RRB-

added

to

the

triolein

prior

to

deployment

has

been

shown

to

enhance

the

use

of

SPMDs

by

accounting

for

site-specific

variables

-LSB-

-RSB-

The

PRCs

are

gradually

lost

from

the

sampler

and

thus

permit

an

exposure

adjustment

factor

or

depuration

rate

to

be

calculated

which

adjusts

for

changes

in

sampling

rate

Lipid-based

passive

air

samplers

have

also

been

developed

and

deployed

for

air

sampling

of

PCBs

and

OCPs

-LSB-

-RSB-

however

more

recently

designs

based

on

polyurethane

foam

-LRB-

PUF

-RRB-

and

XAD

resin

have

become

more

widely

applied

-LSB-

-RSB-

Care

must

be

taken

to

prepare

and

transport

the

samplers

under

clean

conditions

Following

deployment

which

is

usually

for

several

months

for

lipid-based

and

PUF

samplers

-LSB-

-RSB-

for

up

to

one

year

for

XAD

-LSB-

-RSB-

samplers

are

placed

in

transport

containers

and

returned

to

the

lab

PRCs

are

also

often

added

to

the

passive

air

samplers

-LSB-

-RSB-

Sample

storage

and

handling

A

basic

requirement

for

analytical

laboratories

involved

in

the

measurement

of

PCBs

and

OCPs

is

the

availability

of

freezer

and

refrigerator

capacity

for

sample

storage

and

archiving

Wells

and

Hess

-LSB-

-RSB-

and

ICES

-LSB-

-RSB-

provide

recommendations

for

storage

of

biological

and

sediment

samples

Kiriluk

et

al.

-LSB-

-RSB-

found

no

significant

differences

in

concentrations

of

PCBs

in

whole

fish

homogenates

stored

at

or

°C

over

four

years

Norstrom

and

Won

-LSB-

-RSB-

observed

dehydrochlorination

of

DDT

in

long-term-archived

egg

homogenates

which

they

attributed

to

reactions

occurring

during

freeze-drying

De

Boer

and

Smedes

-LSB-

-RSB-

found

no

significant

changes

in

the

concentrations

of

PCBs

and

DDT

components

in

fish

tissue

stored

at

to

°C

in

the

dark

for

up

to

months

However

they

did

find

changes

in

lipid

extractability

caused

by

oxidation

of

triglycerides

to

free

fatty

acids

The

authors

pointed

out

that

this

could

affect

calculations

of

lipid-normalized

concentrations

To

minimize

any

effects

they

recommended

long-term

-LRB-

year

-RRB-

storage

at

°C

Sample

preparation

Wells

et

al.

-LSB-

-RSB-

noted

that

sample

preparation

affected

the

magnitude

of

the

variance

in

the

analysis

of

PCB

congeners

in

mussel

tissue

They

found

that

freeze-drying

samples

reduced

recoveries

of

OCPs

and

PCBs

probably

due

to

tighter

binding

and

occlusion

of

residues

in

the

dried

material

Volatilization

losses

might

also

occur

during

freeze-drying

of

volatile

compounds

such

as

HCB

and

there

is

a

greater

potential

for

contamination

in

the

lab

-LSB-

-RSB-

Although

freeze-drying

has

been

recommended

by

some

authors

for

sediments

and

soils

-LSB-

-RSB-

lower

recoveries

of

PCBs

from

freeze-dried

sediments

have

also

been

reported

-LSB-

-RSB-

Karl

-LSB-

-RSB-

noted

that

loss

of

water

led

to

an

increase

in

OCP

concentrations

in

fish

products

during

processing

Thus

in

general

maintaining

environmental

sample

tissues

and

sediments

in

their

original

wet

state

is

regarded

as

the

most

appropriate

approach

for

preparing

samples

for

PCB/OCP

analysis

Furthermore

avoiding

a

drying

step

minimizes

potential

contamination

from

lab

air

particularly

in

the

case

of

PCBs

that

are

ubiquitous

contaminants

of

older

-LRB-

-RRB-

buildings

-LSB-

-RSB-

Using

wet

material

also

avoids

possible

volatilization

losses

Instead

homogenized

samples

should

be

mixed

with

a

desiccant

such

as

sodium

sulfate

Celite

or

Hydromatrix

to

bind

water

The

desiccant

must

be

certified

to

be

free

of

analyates

e.g.

by

heating

at

high

temperature

in

the

case

of

sodium

sulfate

or

pre-extraction

-LRB-

Celite

Hydromatrix

-RRB-

Tables

and

provide

general

guidance

for

various

preparation/extraction

and

isolation/QA

steps

in

the

analysis

of

PCBs

and

OCPs

and

sources

of

information

Starting

with

sample

preparation

the

basic

approach

is

to

assure

that

the

sample

is

prepared

for

extraction

in

a

room

that

is

free

from

significant

contamination

Ideally

this

would

involve

a

well-ventilated

lab

with

air

prefiltered

through

HEPA

and

carbon

filters

but

any

clean

chemical

laboratory

facility

should

be

adequate

for

most

work

on

PCBs

and

OCPs

in

most

matrices

except

water

or

soils

and

sediments

from

remote

locations

Laboratory

buildings

built

after

about

are

likely

to

be

free

of

PCB-containing

materials

-LRB-

electrical

equipment/paints/sealants

-RRB-

or

OCPs

used

as

insecticides

-LRB-

or

termiticides

in

foundations

-RRB-

because

of

the

effects

of

bans

on

the

use

of

these

substances

promulgated

during

the

and

Table

techniques

used

for

solid

environmental

samples

-LRB-

from

Lopez-Avila

-LSB-

-RSB-

Wells

and

Hess

-LSB-

-RSB-

-RRB-

TechniqueOverviewMethod

referenceConventional

SoxhletSample

desiccant

mixture

in

glass

or

paper

thimble

is

leached

with

warm

-LRB-

condensed

-RRB-

solvent

for

hrs

Solvents

are

e.g.

diethyl

ether

DCM

hexaneEPA

-LSB-

-RSB-

Automated

Soxhlet

-LRB-

e.g.

Soxtec

-RRB-

Extraction

thimble

is

immersed

in

boiling

solvent

-LRB-

min

-RRB-

then

raised

for

Soxhlet

extraction

Solvent

can

also

be

evaporated.EPA

-LSB-

-RSB-

Supercritical

fluid

extraction

-LRB-

SFE

-RRB-

Sample

-LRB-

usually

desiccant

-RRB-

placed

in

high-pressure

cartridge

and

carbon

dioxide

at

atm

at

temp

of

°C

passed

through

After

depressurization

analytes

are

collected

in

solvent

trapEPA

blendingUseful

for

high

water

content

samples

such

as

plant

material

Homogenizes

sample

with

acetone

and

NaCl

-LSB-

-RSB-

Column

extractionSample

-LRB-

desiccant

-RRB-

placed

in

large

column

with

filter

and

stopcock

Eluted

with

large

volume

of

extraction

solvent

e.g.

hexane

DCM

hexane

-LSB-

-RSB-

Sonication-assisted

extractionSample

in

open

or

closed

vessel

immersed

in

solvent

and

heated

with

ultrasonic

radiation

using

ultrasonic

bath

or

probe.Method

-LSB-

-RSB-

Microwave-assisted

extraction

-LRB-

MAE

-RRB-

Sample

in

open

or

closed

vessel

immersed

in

solvent

and

heated

with

microwave

energy.EPA

-LSB-

-RSB-

Pressurized

liquid

extraction

-LRB-

PLE

-RRB-

Sample

-LRB-

usually

desiccant

-RRB-

placed

in

extraction

cartridge

and

solvent

-LRB-

heated

pressurized

-RRB-

passed

through

then

dispensed

in

extraction

vial.EPA

-LSB-

-RSB-

Table

for

various

preparation

extraction

and

isolation

steps

in

the

analysis

of

PCBs

and

OCPsEnvironmental

matrixAnalytical

stepsGeneral

proceduresEPA

or

other

methodSoil

and

sedimentPreparationPrepare

in

a

PCB

and

pesticide-free

room

-LSB-

-RSB-

Avoid

air-drying

Wet

sieve

if

necessary

to

remove

large

particles

Centrifuge

sediment

to

remove

excess

water.Mix

soils/sediments

with

desiccant

such

as

determination

of

dry

mass

by

oven

drying

For

sediments

total

organic

carbon

should

be

determined.QAOne

blank

soil

CRM

every

ten

samples

spike

all

samples

with

recovery

surrogate

standards

Bake

glassware

overnight

at

°C

or

higher.ExtractionSoxhlet

PLE

sonication

or

MAE

with

acetone

hexane

or

DCMSolvent

evaporation

transfer

to

hexane.Sulfur

removal

with

activated

copper

turnings

required

for

sediment.Isolation

cleanupAlumina

silica

or

Florisil

elutions

non-polar

-LRB-

hexane

-RRB-

and

polar

-LRB-

DCM

hexane

or

equivalent

-RRB-

VegetationPreparationHomogenize

using

food

chopper

or

blender

Cryoblending

using

liquid

nitrogen

or

dry

ice

is

useful

Mix

with

dessicant

Separate

determination

of

dry

mass

by

oven-drying

-LSB-

-RSB-

QASame

as

soil

Use

vegetation

CRM

if

possibleExtractionSame

as

soil.Isolation

cleanupSame

as

soil.Aquatic

biotaPreparationSelect

muscle

or

liver

depending

on

species

For

mussels

and

crustaceans

use

soft

tissue

Select

tissue

that

has

not

been

in

contact

with

the

sample

container

Homogenize

using

food

chopper

or

blender

Cryoblending

is

useful

-LSB-

-RSB-

Mix

with

drying

agent

Separate

determination

of

lipid

content.QASame

as

soil

Use

fish

or

mussel

SRMs.ExtractionSoxhlet

pressurized

liquid

extraction

or

column

extraction

Use

acetone

hexane

or

DCM.Isolation

cleanupRemove

lipid

using

gel

permeation

chromatography

if

possible

or

by

repeated

washing

of

the

extract

with

sulfuric

acid

Follow

with

fractionation

on

silica

or

Florisil

columns

as

described

for

soil.Marine

mammal

blubberPreparationSelect

blubber

that

has

not

been

in

contact

with

the

sample

container

Blend

or

hand-mix

with

drying

agent

Separate

determination

of

lipid

content

-LSB-

-RSB-

QASame

as

soil

Use

fish

oil

or

marine

mammal

SRMs.Isolation

cleanupSame

as

for

fish

extracts.Air

-LRB-

high

volume

-RRB-

Extraction

QA

and

cleanupAssuming

that

air

is

collected

on

polyurethane

foams

or

XAD

resin

these

would

be

extracted

in

a

Soxhlet

or

pressurized

liquid

extractor

Other

steps

as

for

soil

or

sediments

-LSB-

-RSB-

Semi-permeable

membrane

devices

-LRB-

SPMD

-RRB-

PreparationSPMDs

would

be

removed

from

their

transport

cases

and

rinsed

with

precleaned

water

to

remove

accumulated

dust

-LRB-

air-borne

samplers

-RRB-

or

periphyton

-LRB-

water

samplers

-RRB-

-LSB-

-RSB-

QAUse

PRCsExtraction

and

cleanupAssuming

that

the

SPMD

is

lipid-based

extraction

of

POPs

by

dialysis

into

hexane

would

be

achieved

in

a

large

glass

cylinder.Water

-LRB-

including

melted

snow

ice

and

wet

precipitation

-RRB-

ExtractionLiquid

liquid

SPE

-LRB-

e.g.

-RRB-

extraction

for

small

-LRB-

L

-RRB-

samples

or

modified

Speedisk

for

L.US

EPA

-LSB-

-RSB-

and

-LSB-

-RSB-

QA

and

cleanupPre-spike

XAD

columns

with

surrogates.Blood

plasmaExtractionExtract

blood

plasma

with

ammonium

sulfate

ethanol/hexane

-LRB-

-RRB-

or

SPE

extraction

-LSB-

-RSB-

Determine

lipid

content.QASame

as

fish

Use

NIST

SRM.Isolation

and

cleanupSulfuric

acid

partitioning

to

remove

lipids.Acid

base

silica

for

additional

lipid

removal.MilkExtractionLiquid

liquid

partitioning

with

acetone

hexane

or

SPE

extraction

Determine

lipid

content

-LSB-

-RSB-

QABCR

SRM

milk

powder.Isolation

and

cleanupAs

with

plasma

Recommended

extraction

and

isolation

techniques

for

PCBs

and

OCP

Recovery

surrogates/internal

standards

A

standard

QA

step

in

the

analysis

of

PCB/OCPs

is

to

include

surrogate

recovery

standards

in

each

sample

These

are

generally

one

or

two

PCB

congeners

-LRB-

e.g.

and

-RRB-

and

OCP-related

unlabeled

compounds

such

as

pentachloronitrobenzene

endrin

ketone

and

other

compounds

that

are

readily

separated

from

individual

OCPs

and

not

commonly

found

in

the

environment

If

GC

MS

is

being

used

as

the

detection

system

then

or

deuterated

surrogates

should

be

used

These

standards

are

carefully

added

by

pipetting

the

appropriate

volume

of

a

standard

solution

onto

the

sample

matrix

prior

to

extraction

Surrogates

do

not

define

absolute

recoveries

because

they

are

not

incorporated

into

the

matrix

however

they

do

provide

information

on

analyte

recovery

throughout

the

isolation

process

and

can

also

provide

sample-to-sample

extraction

efficiency

comparability

If

bioanalytical

techniques

are

being

used

to

screen

extracts

it

may

not

be

possible

to

include

recovery

standards

particularly

since

they

may

respond

similarly

to

the

native

compounds

Extraction

techniques

The

appropriately

prepared

sample

can

then

be

extracted

by

any

one

of

a

number

of

techniques

-LRB-

Table

-RRB-

The

main

points

to

consider

are

to

allow

adequate

exposure

time

for

the

solvent

system

in

the

sample

matrix

and

to

limit

sample

handing

steps

i.e.

avoid

filtration

steps

by

using

Soxhlet

-LRB-

sample

in

a

glass

thimble

-RRB-

extraction

columns

-LRB-

sample

matrix

eluted

after

soaking

in

solvent

-RRB-

or

semi-automated

systems

-LRB-

e.g.

pressurized

liquid

extractors

PLEs

-RRB-

Cross-contamination

from

residues

left

behind

by

high

levels

in

other

samples

is

a

concern

at

this

stage

and

equipment

must

be

thoroughly

cleaned

and

checked

from

batch

to

batch

Purity

of

extraction

solvents

is

a

major

consideration

here

Only

high-purity

glass-distilled

solvents

should

be

used

because

later

evaporation

steps

will

concentrate

any

contaminants

PLE

is

increasingly

being

used

to

replace

Soxhlet

and

column

extraction

methods

-LSB-

-RSB-

PLE

uses

much

less

solvent

than

Soxhlet

or

column

elution

However

it

suffers

the

disadvantage

of

initial

high

cost

and

the

need

for

a

stable

power

supply

to

avoid

premature

instrument

shutdown

Also

operation

of

an

automated

PLE

requires

regular

scheduled

maintenance

by

trained

service

personnel

Preparation

of

a

homogeneous

dry

sample

from

wet

tissue

or

sediment

for

PLE

can

be

a

challenge

due

to

the

limited

size

of

PLE

extraction

vials

currently

set

at

ml

A

US

EPA

method

-LRB-

-RRB-

using

PLE

for

solid

waste

extraction

is

available

-LSB-

-RSB-

This

method

recommends

acetone/hexane

-LRB-

v

v

-RRB-

or

acetone/dichloromethane

-LRB-

DCM

-RRB-

for

extraction

of

PCBs

from

solid

waste

and

these

solvent

systems

appear

to

be

the

most

commonly

used

-LSB-

-RSB-

There

has

been

a

recent

trend

toward

not

using

chlorinated

-LRB-

potentially

toxic

-RRB-

solvents

such

as

chloroform

and

DCM

due

to

concerns

over

exposure

to

lab

personnel

Binary

mixtures

such

as

hexane/acetone

-LRB-

-RRB-

are

regarded

as

equally

effective

for

the

extraction

of

POPs

from

solid

samples

-LSB-

-RSB-

In

general

extraction

with

a

polar

apolar

binary

mixture

has

been

found

to

be

more

efficient

for

recovering

OCPs

and

PCBs

from

fish

tissues

of

low

lipid

content

than

an

apolar

solvent

-LSB-

-RSB-

The

time

and

solvent-consuming

nature

of

Soxhlet

extraction

-LRB-

or

related

techniques

involving

percolation

of

a

solvent

through

the

sample

-RRB-

is

generally

thought

to

be

related

to

the

slow

diffusion

and

desorption

of

the

analytes

from

the

sample

matrix

Semivolatile

compounds

such

as

naphthalenes

can

also

be

lost

from

Soxhlet

apparatus

via

volatilization

-LSB-

-RSB-

The

use

of

microwave

sonication

supercritical

fluids

or

elevated

temperatures

and

pressure

-LRB-

as

in

PLE

-RRB-

increases

the

rates

of

diffusion

and

desorption

and

thus

speeds

up

extraction

-LSB-

-RSB-

Pressurized

hot

water

extraction

has

even

been

used

to

extract

PCBs

from

sediment

and

soil

Under

pressure

the

dielectric

constant

of

the

water

can

be

manipulated

to

facilitate

the

extraction

of

nonpolar

analytes

-LSB-

-RSB-

Sonication

microwave-assisted

extraction

-LRB-

MAE

-RRB-

and

supercritical

fluid

-LRB-

SFE

-RRB-

extraction

have

all

been

successfully

employed

to

recover

PCBs

and

OCPs

from

solid

samples

-LRB-

Table

-RRB-

Soxhlet

is

regarded

as

more

reliable

than

sonication

SFE

or

shake

flask-type

methods

and

equivalent

to

-LRB-

but

not

as

rapid

as

-RRB-

MAE

and

PLE

for

a

wide

range

of

environmental

matrices

-LSB-

-RSB-

Blood

plasma

lipids

can

be

rapidly

extracted

using

conventional

solvent

partitioning

using

a

mixture

of

ammonium

sulfate/ethanol/hexane

-LRB-

-RRB-

-LSB-

-RSB-

Solid-phase

extraction

using

cartridges

is

also

a

proven

technique

-LSB-

-RSB-

Needham

et

al.

-LSB-

-RSB-

have

reviewed

methods

for

the

analysis

of

POPs

in

human

milk

PCB/OCPs

can

be

extracted

from

milk

samples

using

conventional

lipid

extraction

techniques

involving

liquid

liquid

extraction

with

hexane/acetone

-LSB-

-RSB-

Blending

with

acetonitrile

and

potassium

oxalate

-LSB-

-RSB-

followed

by

phase

extraction

has

also

been

used

in

recent

studies

-LSB-

-RSB-

Water

sampling

devices

such

as

solid-phase

extraction

-LRB-

SPE

-RRB-

cartridges

XAD

or

SPMDs

are

extracted

by

elution

or

dialysis

-LRB-

with

hexane

for

lipid-based

SPMDs

-RRB-

The

elution

of

reverse-phase

or

XAD

resin

water

sampler

cartridges

generally

involves

the

use

of

a

water

miscible

solvent

first

to

remove

water

followed

by

a

solvent

of

intermediate

polarity

such

as

DCM

methyl

t-butyl

ether

or

ethyl

acetate

Combined

extracts

are

then

partitioned

into

hexane

Usenko

et

al.

-LSB-

-RSB-

compared

six

different

SPE

devices

for

the

recovery

of

PCBs

and

OCPs

from

natural

waters

These

included

resin

disks

and

various

and

divinyl

benzene-based

adsorbents

They

found

that

products

particularly

Speedisk

a

modified

divinylbenzene

solid-phase

extraction

device

gave

the

best

overall

recoveries

Another

water

sampling

device

solid-phase

microextraction

-LRB-

SPME

-RRB-

involves

immersing

a

polydimethylsiloxane-coated

syringe

into

ml

samples

Hydrophobic

compounds

are

adsorbed

onto

the

coated

fiber

and

the

syringe

then

placed

into

a

hot

injection

liner

which

desorbs

these

compounds

into

the

GC

-LSB-

-RSB-

The

benefit

of

this

approach

is

that

it

requires

no

solvent

or

multistepped

cleanup/concentration

procedures

A

drawback

is

that

the

adsorption

efficiency

can

be

affected

by

complex

water

matrices

and

may

not

be

suitable

for

all

water

sample

types

-LSB-

-RSB-

Particulate

phases

collected

by

filtration

on

glass

fiber

filters

are

treated

like

sediments

and

should

be

extracted

by

Soxhlet

or

pressurized

liquid

extraction

Determination

of

lipid

content

Lipid

contents

of

biological

samples

should

be

determined

during

the

analysis

of

POPs

Most

studies

have

determined

total

extractable

lipid

gravimetrically

by

drying

a

fraction

of

the

sample

extract

to

constant

weight

-LSB-

-RSB-

However

results

can

vary

widely

among

laboratories

due

to

different

extraction

efficiencies

of

various

combinations

of

solvent

and

extraction

apparatus

-LSB-

-RSB-

The

benchmark

method

for

total

lipid

is

that

of

Bligh

and

Dyer

-LSB-

-RSB-

A

modified

version

of

this

method

has

improved

sample

handling

and

method

precision

-LSB-

-RSB-

Smedes

-LSB-

-RSB-

demonstrated

that

propanol

cyclohexane

water

-LRB-

-RRB-

was

an

effective

substitute

for

the

Bligh

and

Dyer

chloroform

methanol

water

The

Smedes

method

gave

more

consistent

results

for

extractable

lipids

in

fish

tissue

with

low

lipid

content

-LRB-

lipid

-RRB-

Samples

with

very

low

fractions

of

lipid

such

as

blood

plasma

are

best

analyzed

using

a

colorimetric

method

-LSB-

-RSB-

Isolation

of

analytes

from

coextractives

There

are

two

aspects

to

this

phase

of

POPs

analysis

The

analytes

must

be

separated

from

nonvolatile

materials

which

affect

the

performance

of

GC

columns

such

as

pigments

inorganic

sulfur

and

triglycerides

Also

there

is

a

need

to

separate

the

OCPs

and

PCBs

from

each

other

as

much

as

possible

prior

to

GC

analysis

in

order

to

limit

coelution

problems

These

isolation

steps

are

also

useful

and

sometimes

essential

for

the

application

of

bioanalytical

methods

to

PCBs/OCPs

and

dioxin-like

activity

-LRB-

See

Bioanalytical

methods

for

the

quantification

of

OCPs

and

PCBs

-RRB-

Adsorption

cleanup

columns

Separation

of

PCB/OCPs

from

coextractives

can

be

relatively

straightforward

for

low-lipid

samples

such

as

soils

sediments

and

vegetation

-LRB-

Table

-RRB-

Generally

small

silica

gel

or

Florisil

columns

-LRB-

either

prepared

in

the

lab

or

pre-purchased

-RRB-

should

suffice

The

purpose

of

this

step

is

to

remove

coextractive

pigments

and

to

separate

nonpolar

PCBs

-LRB-

plus

p

p

DDE

-RRB-

from

more

polar

OCPs

-LRB-

HCH

most

chlordanes

dieldrin/endrin

-RRB-

This

is

achieved

by

applying

the

extract

in

a

small

volume

of

apolar

solvent

to

fractionation

by

eluting

with

hexane

followed

by

one

or

two

other

elutions

of

increasing

polarity

Polar

compounds

are

retained

on

the

column

Basic

alumina

and

silica

gel

columns

have

been

effective

for

the

separation

of

OCPs

from

fish

lipids

-LSB-

-RSB-

although

there

is

the

possibility

of

minor

losses

due

to

dehydrochlorination

of

some

OCPs

e.g.

p

p

DDT

on

the

alumina

The

effectiveness

of

these

adsorption

columns

depends

on

the

mass

and

the

water

content

of

the

adsorbent

together

with

the

polarity

of

the

solvent

In

general

g

of

absorbent

is

used

in

a

cm-diameter

column

with

silica

gel

or

Florisil

deactivated

with

a

low

percentage

of

water

-LRB-

-RRB-

-LSB-

-RSB-

Typically

the

sample

is

applied

to

the

top

of

the

column

in

hexane

and

then

a

first

elution

solely

of

hexane

separates

PCBs

from

many

OCPs

Subsequent

elutions

with

hexane

diethyl

ether

or

hexane

DCM

recover

the

OCPs

-LRB-

p

p

DDT

dieldrin

toxaphene

-RRB-

-LSB-

-RSB-

Alumina

and

Florisil

have

the

capacity

to

retain

about

mg

lipid

per

g

of

adsorbent

-LSB-

-RSB-

Size-exclusion

columns

For

high-lipid

samples

-LRB-

lipid

-RRB-

such

as

some

fish

tissues

-LRB-

e.g.

salmonid

muscle

cod

livers

-RRB-

and

marine

mammal

blubber

a

lipid

removal

step

must

be

included

This

can

be

achieved

using

size

exclusion

or

gel

permeation

chromatography

-LRB-

GPC

-RRB-

either

in

automated

systems

using

HPLC

columns

or

by

gravity

flow

columns

A

g

bed

of

Bio-Beads

a

neutral

porous

styrene

divinylbenzene

resin

-LRB-

BioRad

Laboratories

Hercules

CA

USA

-RRB-

can

accommodate

up

to

g

of

lipid

and

achieves

the

separation

of

fish

lipids

from

most

PCBs

and

OCPs

with

a

size

exclusion

of

Da

-LSB-

-RSB-

Equivalent

HPLC

size-exclusion

columns

can

be

used

-LSB-

-RSB-

The

advantages

of

GPC

are

that

it

is

nondestructive

and

that

columns

can

be

reused

A

disadvantage

is

a

requirement

for

large

volumes

of

purified

solvent

-LRB-

low-pressure

or

gravity

systems

-RRB-

or

expensive

columns

-LRB-

HPLC

-RRB-

Automated

GPC

units

are

commercially

available

and

allow

for

unsupervised

elution

of

samples

Due

to

required

rinses

of

the

unit

sample

lines

a

portion

of

the

sample

is

lost

and

must

be

accounted

for

when

calculating

final

analyte

concentrations

GPC

eluates

generally

require

an

adsorption

column

fractionation

step

on

silica

or

Florisil

to

remove

remaining

low

molecular

weight

lipids

waxes

and

pigments

that

are

not

completely

separated

from

the

PCB/OCPs

Lipid

destruction

Lipid

removal

using

sulfuric

acid

washing

or

elution

of

the

extract

through

sulfuric

acid

-LRB-

-RRB-

in

silica

or

KOH-treated

silica

columns

is

also

effective

for

most

PCB/OCPs

but

does

result

in

loss

of

some

analytes

such

as

dieldrin

-LSB-

-RSB-

Ethanolic

KOH

treatment

of

Soxhlet

extracts

is

also

suitable

for

lipid

removal

and

works

well

for

PCBs

-LSB-

-RSB-

but

may

degrade

chlorinated

aliphatics

such

as

DDT

which

is

converted

to

DDE

The

acid

or

base-treated

extracts

containing

the

PCBs

and

OCPs

are

then

subjected

to

an

adsorption

column

fractionation

step

on

silica

or

Florisil

Sulfur

removal

Sulfur

is

coextracted

with

PCBs

and

OCPs

and

presents

a

particular

problem

for

GC

ECD

analysis

of

sediment

extracts

because

of

its

strong

response

in

this

detector

It

is

also

cytotoxic

and

needs

to

be

eliminated

prior

to

use

with

in

vitro

bioassays

-LSB-

-RSB-

Sulfur

can

be

removed

by

GPC

but

can

also

be

removed

using

activated

copper

turnings

-LRB-

washed

with

concentrated

HCl

and

held

in

an

apolar

solvent

-RRB-

or

using

mercury

The

latter

method

removes

sulfur

more

efficiently

but

is

not

recommended

due

to

potential

for

contamination

of

the

lab

and

lab

effluent

Shaking

with

tetrabutylammonium

sulfide

has

also

been

used

to

remove

sulfur

-LSB-

-RSB-

Evaporation

steps

Solvent

evaporation

is

generally

used

several

times

within

all

analytical

methods

for

PCB/OCPs

and

successful

analyte

recoveries

critically

depend

on

minimizing

losses

during

this

step

Surrogate

standards

may

be

added

prior

to

evaporation

to

monitor

compound

losses

-LSB-

-RSB-

The

Pesticide

Analytical

Manual

of

the

US

FDA

-LSB-

-RSB-

includes

a

discussion

of

solvent

evaporation

and

an

overview

of

the

most

widely

used

equipment

rotary

evaporators

Kuderna

Danish

apparatus

and

TurboVap

equipment

The

US

FDA

-LSB-

-RSB-

overview

favors

the

rotary

evaporator

because

of

greater

range

of

use

e.g.

for

temperature-sensitive

and

semivolatile

analytes

but

notes

that

it

is

applicable

to

only

one

sample

while

both

the

TurboVap

and

K

D

apparatus

can

be

set-up

for

multiple

samples

Preparation

for

GC

analysis

Following

fractionation

on

silica

or

Florisil

final

extracts

are

prepared

in

GC

vials

for

analysis

Addition

of

an

internal

standard

to

check

solvent

volume

is

recommended

at

this

stage

Careful

evaporation

is

required

at

this

step

and

only

high-purity

compressed

gas

-LRB-

usually

nitrogen

-RRB-

should

be

used

This

can

be

done

using

a

stream

of

regulated

gas

via

a

disposable

glass

pipet

and

heating

block

or

via

multineedle

devices

-LRB-

e.g.

N-Evap

-RRB-

Quantification

methods

Overview

Numerous

analytical

approaches

are

available

for

quantifying

PCBs

and

OCPs

As

with

extraction/isolation

steps

only

general

comments

are

provided

here

for

GC

analysis

of

ortho-substituted

PCBs

and

OCPs

However

a

major

consideration

is

that

the

laboratory

will

have

access

to

modern

capillary

GC

equipment

and

either

electron

capture

or

mass

spectrometry

detection

Some

general

guidance

on

the

application

of

gas

chromatographic

analysis

of

ortho-substituted

PCBs

and

OCPs

is

provided

in

Table

Cochran

and

Frame

-LSB-

-RSB-

in

their

review

of

the

GC

analysis

of

PCBs

noted

that

separation

requires

attention

to

-LRB-

-RRB-

proper

injection

to

minimize

analyte

band-broadening

-LRB-

-RRB-

choice

of

carrier

gas

-LRB-

-RRB-

optimized

carrier

gas

velocity

-LRB-

-RRB-

GC

oven

programming

-LRB-

-RRB-

column

dimensions

such

as

length

inside

diameter

film

thickness

number

of

plates

and

-LRB-

-RRB-

the

type

of

column

stationary

phase

Bioanalytical

methods

based

on

immunoassays

or

in

vitro

bioassays

for

dioxin-like

activity

have

become

widely

available

over

the

past

ten

years

for

the

screening

of

sample

extracts

for

POPs

These

methods

and

selected

applications

are

briefly

reviewed

in

this

section

GC

injection

ports

Optimization

of

injection

conditions

is

critical

to

proper

GC

analysis

-LSB-

-RSB-

In

the

analysis

of

POPs

and

OCPs

problems

often

occur

with

nonvolatile

coextractives

such

as

triglycerides

and

pigments

that

despite

various

isolation

procedures

are

still

present

in

final

extracts

Most

GC

applications

for

PCB

and

OCP

analysis

have

employed

split/splitless

injection

systems

although

on-column

injection

has

also

been

used

Although

on-column

injection

avoids

artifacts

associated

with

heated

split/splitless

systems

-LRB-

i.e.

degradation

of

labile

compounds

-RRB-

it

requires

highly

clean

extracts

to

avoid

matrix

effects

-LSB-

-RSB-

Retention

gaps

consisting

of

an

empty

capillary

column

have

been

used

to

reduce

these

effects

and

permit

larger

on-column

injection

volumes

Pressure

programming

allows

improved

control

over

carrier

gas

flow

resulting

in

improved

separation

of

PCB

and

OCPs

GC

columns

Fused

silica

open

tubular

capillary

columns

generally

coated

with

nonpolar

or

medium-polarity

chemically

bonded

liquid

phases

are

almost

universally

used

for

GC

separation

of

PCBs

and

OCPs

-LSB-

-RSB-

The

use

of

capillary

columns

revolutionized

PCB

analysis

allowing

identification

of

the

individual

congeners

This

improved

the

comparability

of

the

analytical

data

from

different

sources

and

helped

to

establish

a

basis

for

the

understanding

of

geochemical

cycles

and

toxicological

implications

The

basic

technology

for

separation

of

PCB

congeners

described

by

Mullins

et

al.

-LSB-

-RSB-

has

not

changed

greatly

over

the

years

These

authors

used

a

phenyl

methyl

silicone

phase

and

a

long

temperature

program

-LRB-

min

-RRB-

to

achieve

high-resolution

separation

of

PCB

congeners

Improved

routine

separations

of

PCBs

have

been

achieved

using

m

mm

i.d.

columns

with

hydrogen

carrier

gas

PCBs

within

a

homolog

group

elute

according

to

their

number

of

ortho

chlorines

Coelution

of

congeners

remains

a

problem

for

routine

analysis

by

GC

ECD

However

several

modified

polydimethylsiloxane

phases

with

n-octyl

or

n-octyldecyl

substituents

e.g.

DB-XLB

-LRB-

J&W

Scientific

Folsom

CA

USA

-RRB-

and

HT

-LRB-

SGE

Inc.

Austin

TX

USA

-RRB-

can

resolve

all

but

four

pairs

of

significant

congeners

and

five

pairs

of

minor

congeners

-LSB-

-RSB-

using

mass

spectrometry

detection

The

coelution

of

PCB

congeners

on

the

more

commonly

used

m

columns

is

outlined

in

Table

Coelutions

are

thus

important

even

for

routinely

monitored

congeners

such

as

CB

and

However

separation

of

these

congeners

can

be

routinely

achieved

on

m

phenyl

methyl

silicone

phase

capillary

columns

using

carrier

gas

and

on

n-octyl

phases

as

well

-LSB-

-RSB-

Use

of

dual-column

GC

in

which

the

sample

is

injected

simultaneously

into

nonpolar

and

medium-polar

phase

columns

is

recommended

if

a

suitable

instrument

is

available

Alternatively

confirmation

of

peak

identity

in

a

subset

of

samples

using

a

second

column

of

different

polarity

can

be

done

instead

Although

other

carrier

gases

such

as

He

can

be

used

the

best

peak

resolution

and

efficiency

is

achieved

by

using

Table

PCB

congener

coelutions

on

phenyl

phases

-LSB-

-RSB-

ClassificationaCoeluting

PCBsNumber

of

A

indicates

a

major

Aroclor

congener

Coelution

of

major

OCPs

with

each

other

or

with

PCBs

is

also

a

problem

in

GC

ECD

analysis

despite

preseparation

by

adsorption

chromatography

For

example

p

p

DDD

can

coelute

with

cis-nonachlor

with

a

trans-nonachlor

isomer

-LSB-

-RSB-

p

p

DDE

with

dieldrin

and

and

toxaphene

congener

Parlar

with

Recently

the

coelution

of

and

brominated

diphenyl

ether

congener

has

also

been

noted

-LSB-

-RSB-

Chiral

GC

separation

of

OCPs

and

PCBs

Most

OCPs

on

the

POPs

list

have

optically

active

or

chiral

isomers

-LRB-

e.g.

α-HCH

o

p

DDT

the

main

constituents

of

technical

chlordane

cis

trans-chlordane

heptachlor

as

well

as

chlorobornanes

in

toxaphene

-RRB-

-LSB-

-RSB-

There

are

also

PCB

atropisomers

which

are

also

chiral

as

a

result

of

restricted

rotation

at

the

central

biphenyl

bond

While

PCBs

and

OCPs

are

racemic

mixtures

when

manufactured

microbial

degradation

in

soils

and

water

as

well

as

biotransformation

reactions

in

biota

can

result

in

nonracemic

patterns

in

environmental

samples

Crucial

for

chiral

analysis

is

the

availability

of

chiral

capillary

GC

columns

such

as

those

with

various

cyclodextrins

chemically

bonded

to

a

polysiloxane

These

phases

are

relatively

heat-stable

and

have

low

bleed

-LSB-

-RSB-

Current

methods

range

from

the

simple

use

of

m

chiral

columns

to

a

two-dimensional

heart-cutting

technique

This

involves

a

redirection

of

a

targeted

portion

of

the

sample

after

elution

from

a

methyl/phenyl

polysiloxane

column

into

a

chiral

column

via

a

computer-controlled

pneumatic

valve

This

provides

higher

peak

capacity

and

generally

further

separation

of

chiral

compounds

While

use

of

chiral

GC

separations

is

not

part

of

routine

OCP

analysis

it

is

a

well-developed

technology

that

is

relatively

easy

to

implement

in

existing

GC

ECD

and

GC

MS

instruments

This

technique

has

useful

applications

for

tracking

sources

of

OCPs

and

transformations

of

PCBs

For

example

Jantunen

et

al.

-LSB-

-RSB-

-RRB-

and

Leone

et

al.

-LSB-

-RSB-

have

shown

that

enantiomer

fractions

of

chlordane

isomers

can

be

used

to

identify

emissions

of

this

pesticide

from

soils

Wong

et

al.

-LSB-

-RSB-

calculated

minimum

transformation

rates

for

PCB

atrophisomers

and

in

the

Lake

Superior

food

web

using

enantiomer

ratios

in

predators

and

prey

species

GC

ECD

Since

the

POPs

have

been

determined

by

GC

with

electron

capture

detection

-LRB-

ECD

-RRB-

initially

using

packed

columns

Capillary

GC

ECD

began

to

be

routinely

applied

by

the

early

Use

of

GC

ECD

is

recommended

for

routine

analysis

of

OCPs

except

for

toxaphene

as

well

as

for

ortho-PCBs

-LRB-

Table

-RRB-

but

not

for

non-ortho-PCBs

-LSB-

-RSB-

This

instrumentation

is

widely

available

at

relatively

low

cost

from

at

least

four

instrument

manufacturers

A

substantial

knowledge

base

exists

on

the

use

of

this

technology

GC

ECD

is

capable

of

determining

PCB/OCPs

at

low

ng/g

levels

or

higher

in

environmental

matrices

Although

at

one

time

tritium-based

ECDs

were

once

available

the

detector

is

now

universally

used

This

detector

is

operated

at

high

temperatures

°C

which

makes

it

relatively

unaffected

by

column

bleed

ECD

suffers

from

the

potential

for

false

positives

due

to

interferences

such

as

those

from

sulfur

phthalate

esters

and

negative

peaks

generated

by

hydrocarbons

ECDs

are

normally

operated

with

or

argon/methane

gas

which

combines

with

the

flow

from

the

GC

column

-LRB-

He

or

carrier

gas

-RRB-

Gases

used

for

GC

ECD

must

be

ultrapure

to

protect

both

the

GC

column

-LRB-

which

can

be

oxidized

by

trace

oxygen

or

siloxanes

hydrolyzed

by

trace

water

-RRB-

and

the

ECD

itself

Recent

refinements

in

ECD

technology

include

the

use

of

microcells

which

have

greater

linear

range

than

older

detector

cells

-LSB-

-RSB-

and

can

provide

greater

sensitivity

Table

guidance

on

GC

analysis

and

data

reporting

for

PCBs

and

OCPsGC

detectorAnalytesConfigurationAdvantages/disadvantagesDetection

limitsaCapillary

GC

with

electron

capture

detectionAll

ortho-subsituted

PCBs

all

OCPs

on

the

POPs

list

except

or

m

mm

id

Column

with

carrier

gas

Dual

column

nonpolar

-LRB-

-RRB-

and

intermediate

polarity

columns

-LRB-

-RRB-

Relatively

inexpensive

and

easy

to

operate

Similar

response

factors

for

most

OCs.DDT

DDE

pgGood

sensitivity

for

all

POPs

Adequate

for

routine

tasks

High

potential

for

misidentification

of

some

POPs

due

to

coeluting

peaks.HCB

pgQuadrupole

mass

spectrometry

in

electron

ionization

-LRB-

EI

-RRB-

modeAll

PCBs

all

OCPs

on

the

POPs

list

except

m

mm

i.d.

low-bleed

columns

with

He

carrier

gas

Selected

ion

mode

for

target

POPs

Moderately

expensive

and

more

complex

to

operate

and

maintain

Newer

instruments

-LRB-

post

-RRB-

have

adequate

sensitivity

for

routine

POPs

monitoring

at

low

pg/μL

concentrations

Much

less

potential

for

misidentification

than

with

ECD.DDT

DDE

pgHCB

pgDieldrin

pgToxaphene

pg

-LRB-

as

tech

mixture

-RRB-

Quadrupole

mass

spectrometry

in

electron

capture

negative

ionization

-LRB-

ECNIMS

-RRB-

modeToxaphene

and

other

highly

chlorinated

OCPs

and

PCB

with

m

mm

i.d.

low-bleed

columns

with

He

carrier

gas

Selected

ion

mode

for

target

POPs.Comparable

sensitivity

in

ECNIMS

mode

to

ECD

in

SIM

mode

for

some

POPs

Much

less

potential

for

misidentification

than

with

ECD.DDT

DDE

pgHCB

pgDieldrin

pgToxaphene

pg

-LRB-

as

tech

mixture

-RRB-

Ion

trap

mass

spectrometry

using

MS/MS

modeAll

PCBs

All

OCPs

on

the

POPs

m

mm

i.d.

low-bleed

columns

with

He

carrier

gas

Same

columns

as

quadrupole

MS.Comparable

sensitivity

to

ECD

in

MS/MS

mode

for

some

POPs

Much

less

potential

for

misidentification

than

with

ECD.DDT

DDE

pgHCB

pgDieldrin

pgToxaphene

pg

-LRB-

as

tech

mixture

-RRB-

High-resolution

magnetic

sector

mass

spectrometry

in

electron

ionization

-LRB-

EI

-RRB-

modeAll

PCBs

all

OCPs

on

the

POPs

list

except

m

mm

i.d.

low-bleed

columns

with

He

carrier

gas

Selected

ion

mode

for

target

POPs

at

resolution.Comparable

sensitivity

to

ECD

in

SIM

mode

Highly

reliable

identification

at

low

pg/μL

levels.DDT

DDE

pgHCB

pgDieldrin

pgToxaphene

pg

-LRB-

as

tech

mixture

-RRB-

aInstrumental

detection

limits

at

S/N

of

GC

MS

Capillary

GC

coupled

with

mass

spectrometry

-LRB-

GC

MS

-RRB-

revolutionized

environmental

organic

analysis

in

the

-LSB-

-RSB-

particularly

with

the

advent

of

bench-top

instruments

Current

GC

low-resolution

-LRB-

quadrupole

-RRB-

mass

spectrometry

-LRB-

LRMS

-RRB-

instrumentation

is

capable

of

determining

most

PCB/OCPs

at

low

pg

concentrations

using

electron

ionization

-LRB-

EI

-RRB-

in

selected

ion

mode

Electron

capture

negative

ion

ionization

-LRB-

ECNI

-RRB-

is

capable

of

detection

of

low

femtogram

amounts

of

highly

chlorinated

OCPs

such

as

chlordane

and

toxaphene

congeners

In

this

mode

a

reagent

gas

usually

methane

is

introduced

into

the

ion

source

and

negative

ions

are

monitored

The

ECNI

mode

also

has

a

more

limited

linear

range

than

the

EI

mode

is

more

difficult

to

operate

routinely

due

to

greater

sensitivity

to

temperature

variations

and

needs

more

frequent

cleaning

due

to

the

reaction

of

the

reagent

gas

with

surfaces

in

the

ion

source

GC

ion

trap

MS

-LRB-

ITMS

-RRB-

in

MS/MS

mode

offers

an

equivalent

sensitivity

to

quadrupole

ITMS

in

selected

ion

mode

and

improved

specificity

by

examining

product

ions

of

major

mass

fragments

ITMS

has

been

successfully

applied

to

detect

mono-ortho-PCBs

at

subpicogram

levels

in

a

range

of

environmental

samples

-LSB-

-RSB-

and

to

determine

pg

levels

of

toxaphene

congeners

-LSB-

-RSB-

In

general

both

quadrupole

and

ion

trap

LRMS

can

suffer

from

false

positives

due

to

unit

mass

resolution

Thus

experienced

analysts

are

needed

to

interpret

results

using

confirmatory

information

such

as

full-scan

analyses

fragmentation

patterns

and

ion

ratios

GC

coupled

to

HRMS

provides

much

higher

specificity

for

individual

PCB/OCPs

due

to

its

ability

to

provide

millimass

resolution

and

can

also

be

used

for

the

determination

of

all

ortho-substituted

PCBs

-LRB-

e.g.

EPA

Method

-LSB-

-RSB-

-RRB-

and

OCPs

too

and

provides

a

very

high

level

of

confidence

in

the

results

compared

to

GC

ECD

and

LRMS

The

use

of

GC

MS

allows

for

the

application

of

isotope-dilution

techniques

and

these

have

increasingly

come

into

routine

use

for

PCB/OCP

analysis

in

environmental

samples

due

to

the

sensitivities

of

the

latest

generation

of

quadrupole

and

ion-trap

MS

systems

-LSB-

-RSB-

A

wide

range

of

PCBs

and

OCPs

are

available

as

compounds

from

several

chemical

supply

companies

which

when

added

at

the

extraction

step

increase

precision

and

reproducibility

for

the

native

analytes

Bioanalytical

methods

for

the

quantification

of

OCPs

and

PCBs

Enzyme-linked

immunoabsorbent

assays

-LRB-

ELISA

-RRB-

ELISAs

have

been

used

to

quantify

most

DDT/DDE

HCH

isomers

toxaphene

and

cyclodiene

OCPs

as

well

as

PCBs

in

environmental

samples

-LSB-

-RSB-

ELISAs

are

based

on

competitive

binding

in

which

the

binder

molecule

an

excess

amount

of

labeled

analyte

or

coating

antigen

and

the

target

analyte

are

allow

to

approach

equilibrium

The

sample

antigen

competes

with

the

coated

antigen

for

binding

sites

on

the

labeled

antibody

after

a

wash

step

detection

is

performed

by

adding

substrate

and

chromophore

Quantification

is

generally

performed

via

spectrophotometric

measurements

and

the

amount

of

analyte

in

the

sample

is

interpolated

from

a

calibration

curve

Although

widely

used

to

screen

for

current-use

herbicides

and

insecticides

as

well

as

their

polar

metabolites

-LSB-

-RSB-

the

development

of

competitive

immunoassays

for

neutral

hydrophobic

OCPs

has

lagged

-LSB-

-RSB-

This

is

in

part

due

to

the

need

for

low

detection

limits

Also

ELISA

analysis

for

some

OCPs

such

as

HCH

-LRB-

and

lindane

-RRB-

has

been

challenging

due

to

the

small

size

of

the

HCH

molecule

its

structural

symmetry

and

possibly

most

importantly

its

lack

of

aromatic

structures

or

other

atomic

groups

capable

of

supporting

delocalized

electron

networks

-LSB-

-RSB-

The

development

of

a

sensitive

ELISA

for

DDT

required

synthesis

of

a

ligand

with

Cl

replaced

by

b-alanine

carboxamide

and

lindane

after

degradation

to

trichlorobenzenes

-LSB-

-RSB-

Commercial

ELISA

kits

for

detection

of

PCBs

and

most

OCPs

are

available

from

Millipore

Corp.

-LRB-

Billerica

MA

USA

-RRB-

and

Strategic

Diagnostics

-LRB-

Newark

DE

USA

-RRB-

Detection

limits

for

PCBs

and

OCPs

are

typically

in

the

low

μg/L

range

in

water

or

μg/g

range

in

soil

and

plant

extracts

These

kits

are

meant

to

be

used

with

relatively

little

sample

preparation

and

although

semiquantitative

are

ideal

for

screening

samples

and

complement

more

elaborate

techniques

involving

GC

analysis

-LRB-

Fig.

-RRB-

Fig.

of

the

basic

components

of

an

ELISA

for

detection

of

OCPs

and

PCBs

in

environmental

samples

or

extracts

Sample

antigen

-LRB-

analyte

-RRB-

competes

with

antigen

for

binding

sites

on

coating

protein

after

a

wash

step

detection

is

performed

by

adding

substrate

and

chromophore

Shivaramaiah

et

al.

-LSB-

-RSB-

used

an

ELISA

specific

for

DDE

to

survey

DDT

residues

in

surface

soils

in

three

river

valleys

of

northern

New

South

Wales

Australia

The

technique

allowed

the

analysis

of

large

numbers

of

samples

thus

permitting

the

areas

of

contamination

to

be

mapped

Galloway

et

al.

-LSB-

-RSB-

used

an

ELISA

to

detect

PCBs

in

extracts

of

mussels

from

New

Bedford

Harbor

-LRB-

USA

-RRB-

The

ELISA

and

GC

ECD

results

were

highly

correlated

although

the

latter

were

about

lower

than

quantitation

by

GC

Samples

were

extracted

and

lipid

partially

removed

by

chromatography

on

Florisil

prior

to

exchanging

the

sample

into

a

phosphate

buffer/methanol

solution

for

the

immunoassay

The

use

of

the

ELISA

saved

additional

isolation

steps

and

GC

analysis

In

general

fatty

coextractive

materials

must

be

removed

prior

to

application

of

ELISAs

for

OCPs

Skerritt

et

al.

-LSB-

-RSB-

examined

the

application

of

ELISAs

for

DDT

and

cyclodiene

insecticides

heptachlor

and

endosulfan

in

plant-derived

foods

They

found

that

cleanup

was

necessary

for

foods

that

yielded

highly

colored

extracts

such

as

coffee

and

spinach

and

for

oily

products

such

as

cottonseed

Quality

assurance

issues

for

PCBs

and

OCPs

Ancillary

data

A

significant

amount

of

ancillary

data

is

required

in

order

for

the

PCB/OCPs

measurements

to

be

properly

interpreted

in

terms

of

temporal

and/or

spatial

trends

and

exposure

of

wildlife

and

humans

Tanabe

and

Subramanian

-LSB-

-RSB-

have

extensively

reviewed

the

factors

to

be

considered

for

the

selection

of

bioindicator

species

including

human

tissues

Analytical

lab

reports

need

to

include

quality

assurance

data

so

that

results

and

lab

performance

can

be

assessed

independently

-LSB-

-RSB-

as

outlined

in

Table

The

objective

here

would

be

to

have

a

record

of

the

entire

processing

of

the

sample

from

preparation

through

to

reporting

concentrations

that

can

be

evaluated

independently

Therefore

the

individual

labs

should

report

concentrations

for

analytes

blanks

and

reference

materials

Data

reports

should

also

include

instrument

calibration

results

and

recoveries

This

would

enable

method

detection

limits

-LRB-

MDLs

-RRB-

to

be

calculated

independently

of

the

lab

if

necessary

Table

reporting

dataset

for

POPs

analysisInformationDetailsSampling

protocolsMethod

number

size

and

representativenessStorage

temperature

and

locationSample

tracking

informationDate

received

date

analyzed

lab

batch

number

or

other

unique

identifiedPublished

analytical

methode.g.

EPA

methodLimit

of

detection/quantificationSee

QA

procedures

BlanksReagents

and

also

field

blanks

if

possibleRecoveriesDuplicatesCalibrationSource

of

standards

date

stocks

preparedSurrogate

and

internal

standardsQA

of

cofactorsSuch

as

lipid

organic

carbon

and

moisture

contentConfirmatory

testse.g.

Use

of

second

GC

column

or

other

detection

systemData

manipulationsBlank

subtraction

recovery

correction

Field

and

lab

blanks

Determination

of

PCBs

and

OCPs

requires

the

analysis

of

blank

samples

because

of

the

ubiquitous

nature

of

these

contaminants

as

discussed

previously

For

air

and

water

the

sampling

media

-LRB-

i.e.

pre-extracted

water

or

the

XAD

resin

cartridges

or

SPMDs

-RRB-

can

serve

as

blanks

Ideally

these

media

should

be

transported

to

the

field

and

exposed

briefly

to

the

sampling

equipment

thus

serving

as

a

field

blank

Additional

samples

of

the

media

should

be

archived

in

the

preparation

lab

for

use

as

lab

blanks

For

soils

and

fatty

samples

US

EPA

Method

for

PCBs

recommends

sand

and

corn

oil

respectively

as

lab

reference

blanks

-LSB-

-RSB-

Clean

facilities

ideally

with

HEPA

and

carbon-filtered

air

are

recommended

but

are

not

essential

for

the

determination

of

PCBs

except

for

ultralow

levels

in

water

Contamination

of

lab

air

can

be

checked

by

use

of

SPMDs

or

by

exposing

in

the

lab

for

a

specified

period

QA

procedures

Key

elements

in

QA/QC

for

POPs

analysis

are

the

use

of

reference

materials

the

use

of

quality

charts

participation

in

interlaboratory

studies

and

the

use

of

guidelines

for

sampling

and

analysis

-LSB-

-RSB-

Recovery

studies

in

which

individual

analytes

are

spiked

into

the

sample

matrix

prior

to

extraction

are

useful

for

determining

the

performance

of

the

analytical

method

However

they

do

not

provide

much

information

on

the

true

extractability

of

analytes

from

naturally

contaminated

matrices

This

can

only

be

accomplished

by

extracting

certified

reference

materials

-LRB-

CRMs

-RRB-

or

if

are

available

for

a

particular

type

of

sample

some

other

well-characterized

material

that

has

been

analyzed

by

an

experienced

reference

lab

-LSB-

-RSB-

Recovery

studies

can

be

also

useful

for

determining

method

detection

limits

if

conducted

at

concentrations

within

times

the

estimated

limit

of

detection

determined

from

the

instrumental

response

or

from

blanks

-LSB-

-RSB-

As

a

routine

measure

spiking

surrogate

recovery

standards

into

each

sample

provides

useful

information

on

losses

of

analyte

from

the

extraction

step

onwards

However

no

single

PCB

or

OCP

can

be

representative

of

all

of

the

organochlorines

being

determined

and

thus

recovery

correction

should

be

performed

with

caution

Isotopically

labeled

surrogates

are

ideal

for

analyses

of

PCBs

and

OCPs

that

are

being

performed

by

LRMS

and

HRMS

and

isotope

dilution

techniques

correct

for

the

recoveries

of

these

surrogates

If

blanks

are

significant

-LRB-

for

example

averaging

greater

than

of

the

average

level

of

total

PCBs

-RRB-

then

blank

correction

should

be

carried

out

This

should

only

be

done

with

a

robust

method

blank

based

on

at

least

seven

samples

or

a

blank

known

to

be

representative

of

a

batch

of

samples

Ferrario

et

al.

-LSB-

-RSB-

subtracted

an

MDL

value

based

on

the

blank

σb

on

the

rationale

that

this

ensured

a

low

probability

-LRB-

-RRB-

of

false

positives

compared

to

subtraction

of

the

average

blank

only

Detection

limits

Detection

limits

for

PCB/OCPs

depend

on

the

analytical

method

but

also

on

the

sample

size

and

QA

considerations

e.g.

information

available

from

blank

or

control

samples

and

recovery

studies

The

selection

of

detection

limits

also

depends

on

the

goals

of

the

program

and

how

much

emphasis

is

placed

on

the

reliability

of

the

results

versus

the

need

to

achieve

broad

geographic

coverage

to

meet

or

exceed

regulatory

or

risk

assessment

guidelines

-LRB-

Electronic

Supplementary

Material

Table

-LSB-

-RSB-

-RRB-

and

to

avoid

reporting

less

thans

for

a

high

proportion

of

samples

A

recent

US

EPA

report

has

reviewed

the

approaches

to

calculating

detection

limits

in

the

analysis

of

POPs

and

other

environmental

contaminants

-LSB-

-RSB-

Detection

limits

are

usually

expressed

as

a

concentration

i.e.

they

are

based

on

the

average

weight

of

the

sample

analyzed

as

summarized

in

Table

The

recommended

method

for

determining

the

MDL

-LSB-

-RSB-

is

to

analyze

a

series

of

samples

as

free

from

the

target

analyte

as

possible

-LRB-

a

minimum

of

seven

replicates

-RRB-

that

have

a

concentration

of

the

analyte

that

is

at

least

equal

to

or

in

the

same

concentration

range

as

-LRB-

within

a

factor

of

five

of

-RRB-

the

estimated

detection

limit

All

of

the

replicate

aliquots

are

processed

through

the

entire

analytical

method

The

standard

deviation

-LRB-

σ

-RRB-

of

the

replicate

measurements

is

determined

and

the

MDL

is

then

determined

by

multiplying

the

standard

deviation

by

the

Student

's

t-value

at

a

percentile

for

n

degrees

of

freedom

The

MDL

is

thus

an

estimate

of

the

measured

concentration

at

which

there

is

confidence

that

a

given

analyte

is

present

in

a

given

sample

matrix

The

MDL

is

defined

by

the

analytical

laboratory

and

is

likely

to

vary

between

labs

because

of

different

blanks

and

instrumental

conditions

Table

limits

defined

by

various

organizationsOrganizationTerminologyCalculationUS

EPAMethod

detection

limit

-LRB-

MDL

-RRB-

Minimum

level

of

quantitation

-LRB-

ML

-RRB-

American

Chemical

SocietyLimit

of

detection

-LRB-

LOD

-RRB-

Limit

of

quantitation

-LRB-

LOQ

-RRB-

International

Organization

for

Standardization

International

Union

of

Pure

and

Applied

Chemistry

-LRB-

ISO/IUPAC

-RRB-

Critical

value

-LRB-

CRV

-RRB-

minimum

detectable

value

-LRB-

MDV

-RRB-

Limit

of

quantitation

-LRB-

LOQ

ISO/IUPAC

-RRB-

The

MDL

is

analogous

to

the

CRV

described

by

Currie

-LSB-

-RSB-

and

reported

by

ISO/IUPAC

which

is

tn

σb

of

a

sample

blank

Note

that

the

t-value

is

based

on

the

percentile

Thus

the

MDL

and

CRV

differ

in

the

multiplier

used

There

may

be

practical

difficulties

with

measuring

some

analytes

if

there

no

blank

value

however

the

σ

of

a

low-concentration

standard

can

be

used

The

MDV

is

similar

to

the

CRV

but

measured

at

the

detection

limit

Limit

of

detection

-LRB-

LOD

-RRB-

described

by

the

American

Chemical

Society

-LSB-

-RSB-

is

equal

to

the

field

blank

b

plus

three

times

the

standard

deviation

of

the

blank

-LRB-

σb

-RRB-

is

numerically

equivalent

to

the

MDL

as

b

approaches

zero

or

when

results

are

blank-subtracted

This

definition

has

been

widely

used

because

of

its

publication

in

the

peer-reviewed

literature

It

should

be

noted

that

the

US

EPA

MDL

and

the

ISO/IUPAC

CRV

implicitly

assume

that

results

are

adjusted

for

interferences

or

blank

values

The

US

EPA

-LSB-

-RSB-

and

other

organizations

have

also

defined

various

lowest

levels

of

quantitation

which

give

a

higher

degree

of

confidence

in

the

results

The

minimum

level

of

quantitation

is

the

lowest

level

at

which

the

entire

analytical

system

must

give

a

recognizable

signal

and

an

acceptable

calibration

point

for

the

analyte

It

is

equivalent

to

the

concentration

of

the

lowest

calibration

standard

assuming

that

all

method-specified

sample

weights

volumes

and

clean

up

procedures

have

been

employed

The

ML

is

calculated

by

multiplying

the

MDL

by

and

rounding

the

results

to

the

number

nearest

to

-LRB-

or

-RRB-

where

n

is

an

integer

-LSB-

-RSB-

The

ACS

LOQ

is

defined

as

being

b

σb

above

the

gross

blank

The

ISO/IUPAC

LOQ

is

defined

as

the

signal

or

analyte

-LRB-

true

-RRB-

value

that

will

produce

estimates

having

a

specified

relative

standard

deviation

-LRB-

RSD

-RRB-

commonly

-LSB-

-RSB-

It

is

calculated

as

where

σQ

is

the

standard

deviation

of

the

blank

and

where

KQ

Table

presents

some

approximate

values

for

MDLs

that

should

be

achievable

assuming

typical

responses

of

ECD

and

MS

systems

as

well

as

three

types

of

bioanalytical

methods

to

various

OCPs/PCBs

and

negligible

blanks

for

the

individual

PCBs

and

OCPs

in

a

g

sample

Table

MDLs

for

individual

PCBs

and

OCPs

-LRB-

ng/g

wet

wt

-RRB-

after

Liem

-LSB-

-RSB-

AnalyteELISA

-LRB-

soil/fly

ash

-RRB-

ECDaMSb

-LRB-

low

resolution

EI-SIM

-RRB-

MSc

-LRB-

high

resolution

EI-SIM

-RRB-

PCB

PCB

p

p

HCB

Total

PCB

aAssumes

MDL

SD

of

low-level

spike

-LRB-

US

EPA

-RRB-

assuming

g

sample

and

a

sample

volume

of

mLbAssumes

use

of

isotope

dilution

-LRB-

-RRB-

surrogates

electron

ionization

selected

ion

monitoring

mode

with

g

sample

and

a

sample

volume

of

mLcAssumes

use

of

isotope

dilution

-LRB-

-RRB-

surrogates

electron

ionization

selected

ion

monitoring

mode

with

g

sample

and

a

sample

final

volume

of

mL

Reference

materials

Certified

reference

materials

-LRB-

CRMs

also

known

as

standard

reference

material

or

SRM

-RRB-

are

essential

for

determining

the

accuracy

of

analytical

methods

for

most

PCBs

and

OCPs

-LSB-

-RSB-

The

CRMs

currently

available

are

shown

in

Table

While

no

single

CRM

is

currently

certified

for

all

POPs

there

are

published

uncertified

values

available

for

a

broad

array

of

individual

PCBs

DDT

isomers

and

toxaphene

congeners

especially

for

NIST

cod

liver

-LSB-

-RSB-

Sediment

CRMs

are

freeze-dried

and

thus

potentially

not

representative

of

sediment

materials

normally

extracted

Some

CRMs

notably

SRM

can

not

be

shipped

outside

of

the

USA

without

CITES

permits

Table

for

PCBs/OCPs

in

biota

and

sediment

-LRB-

adapted

from

de

Boer

and

McGovern

-LSB-

-RSB-

-RRB-

CRMSourceTissue/speciescis-CHLtrans-CHLDieldrinDDTHCBMirexPCB

troutXEDF

Criteria

for

evaluating

the

desirability

and

efficacy

of

different

analytical

methods

in

environmental

monitoring

and

surveillance

Overview

The

data

generated

by

chemical

analytical

and

bioanalytical

methods

for

PCBs/OCPs

are

often

used

to

assess

spatial

and

temporal

trends

of

contamination

in

environmental

media

on

a

national

regional

and

international

basis

The

data

will

also

be

used

by

regulators

and

risk

assessors

to

determine

if

concentrations

exceed

guidelines

Thus

methods

must

give

accurate

results

which

are

comparable

among

labs

and

at

concentrations

which

are

at

or

below

action

limits

for

food

or

guidelines

on

wildlife

protection

-LRB-

see

Electronic

Supplementary

Material

Table

-LSB-

-RSB-

-RRB-

Comparison

of

detection

limits

for

widely

used

instrumentation

for

PCBs

and

OCPs

in

Table

with

guideline

limits

-LRB-

Electronic

Supplementary

Material

Table

-RRB-

suggests

that

conventional

chemical

analytical

methodology

and

bioanalytical

methods

can

meet

and

exceed

these

limits

in

some

cases

by

orders

of

magnitude

Sample

size

lack

of

coextractive

interferences

and

final

volume

are

important

considerations

The

QA

programs

discussed

above

can

assure

laboratory

personnel

that

accurate

and

reproducible

results

are

being

generated

and

can

be

validated

by

participating

in

regional

national

or

international

interlaboratory

comparisons

using

samples

with

assigned

values

-LSB-

-RSB-

In

the

context

of

implementation

of

the

Stockholm

POPs

Convention

global

comparability

is

the

goal

and

thus

successful

participation

in

international

programs

should

be

a

requirement

of

any

participating

lab

The

challenge

for

future

POPs

monitoring

especially

in

developing

countries

will

be

to

assess

the

quality

of

data

and

to

provide

guidance

for

best

laboratory

practices

Interlaboratory

comparisons

Interlaboratory

comparisons

of

POPs

were

conducted

along

with

the

first

environmental

measurements

in

the

late

and

became

widely

adopted

in

the

-LSB-

-RSB-

The

major

international

programs

related

to

PCBs

and

OCPs

are

the

QUASIMEME

-LRB-

Quality

Assurance

of

Information

for

Marine

Environmental

Monitoring

in

Europe

-RRB-

program

-LSB-

-RSB-

and

the

determination

of

OCPs

in

food

organized

in

and

by

the

Global

Environmental

Monitoring

Scheme

-LRB-

GEMS

-RRB-

of

the

World

Health

Organisation

-LRB-

WHO

-RRB-

-LSB-

-RSB-

Other

important

ongoing

programs

are

the

determination

of

OCPs/PCBs

in

human

milk

under

the

auspices

of

AMAP

-LSB-

-RSB-

and

the

intercomparisons

operated

by

the

National

Institute

of

Standards

and

Technology

and

the

Marine

Mammal

Health

and

the

National

Oceanic

Atmospheric

Administration

National

Marine

Fishery

Service

These

programs

have

been

a

major

stimulus

for

improved

analysis

of

POPs

globally

in

the

past

ten

years

The

results

from

interlab

programs

indicate

that

training

and

specific

guidance

on

key

aspects

of

the

analytical

methods

such

as

preparation

of

calibration

solutions

are

important

-LSB-

-RSB-

PCB/OCP

method

accuracy

How

accurate

should

analytical

methods

be

Obviously

they

should

be

accurate

enough

to

identify

changes

in

temporal

or

spatial

trends

in

contaminant

concentrations

-LSB-

-RSB-

Using

the

approach

of

Nicholson

-LSB-

-RSB-

accuracy

is

defined

as

being

certainty

that

the

measured

values

will

fall

within

upper

and

lower

limits

defined

by

where

μ

is

the

true

concentration

σ

is

the

precision

b

is

the

bias

where

tn

and

where

the

dataset

is

normally

distributed

Both

σ

and

b

can

be

calculated

from

multiple

analyses

of

a

CRM

where

σ

is

the

standard

deviation

of

the

analyte

and

b

is

the

relative

percent

deviation

from

the

certified

value

-LRB-

μ

-RRB-

As

a

percentage

of

the

true

value

the

accuracy

is

given

as

Between-laboratory

accuracies

of

have

been

achieved

for

PCB

congeners

among

experienced

labs

participating

in

QUASIMEME

-LSB-

-RSB-

The

European

Commission

-LSB-

-RSB-

has

defined

the

acceptability

of

an

analytical

method

based

on

repeated

analysis

of

PCB/OCPs

in

a

CRM

as

follows

to

for

analytes

in

the

range

of

μg/kg

to

for

analytes

μg/kg

to

μg/kg

to

for

analytes

μg/kg

These

percentages

are

also

recommended

acceptability

guidelines

for

samples

spiked

with

PCBs/OCPs

where

no

CRM

is

available

Emerging

issues

in

analytical

methods

and

future

directions

Analytical

methods

for

trace

organic

analysis

are

constantly

evolving

and

improving

as

can

be

seen

from

recent

reviews

of

environmental

analysis

-LSB-

-RSB-

Although

PCB/OCP

analysis

is

a

mature

area

within

environmental

analytical

chemistry

with

basic

methods

that

have

remained

unchanged

for

the

past

years

there

have

been

many

new

technologies

that

have

been

gradually

adopted

and

undoubtedly

more

will

emerge

in

the

future

Some

emerging

procedures

with

low

environmental

impact

-LRB-

SPME

microscale

glassware

low

solvent

use

etc.

-RRB-

may

be

particularly

suited

for

developing

countries

where

analytical

budgets

are

small

and

product

delivery

times

are

lengthy

Thus

strategies

must

be

considered

that

will

allow

improved

techniques

to

be

adopted

by

such

labs

A

major

development

in

the

analysis

of

POPs

has

been

the

introduction

of

semi-automated

extraction

instruments

for

PLE

-LRB-

Accelerated

Solvent

Extraction

Dionex

Instruments

Sunnyvale

CA

USA

-RRB-

The

PLE

extraction

can

be

combined

with

solid-phase

adsorbents

to

extract

and

isolate

analytes

of

interest

for

example

to

remove

lipids

during

the

extraction

of

POPs

from

fatty

samples

-LSB-

-RSB-

In

general

automated

and

semi-automated

systems

are

available

for

cleanup

and

isolation

of

samples

for

PCB/OCP

using

disposable

solid-phase

cartridges

as

well

as

high-performance/pressure

LC

columns

Advances

in

GC

that

are

potentially

applicable

to

PCB/OCP

analysis

in

developing

countries

are

the

commercial

availability

of

multidimensional

GC

-LRB-

-RRB-

and

fast

GC

In

GCxGC

or

comprehensive

two-dimensional

GC

all

of

the

analyte

mass

is

transferred

to

a

second

column

and

thus

resolving

power

is

increased

by

an

order

of

magnitude

-LSB-

-RSB-

When

applied

to

PCB

separations

using

GCxGC

ECD

three

to

four-fold

lower

LODs

were

obtained

compared

to

one-dimensional

GC

and

dioxin-like

no

and

mo-PCBs

could

be

separated

from

other

congeners

-LSB-

-RSB-

Rapid

GC

separation

of

PCB

congeners

by

fast

GC

were

obtained

on

narrow-bore

-LRB-

mm

-RRB-

columns

which

reduced

peak

widths

and

shortened

total

run

times

for

the

full

PCB

congener

mix

to

minutes

-LSB-

-RSB-

Both

techniques

can

be

run

with

a

micro-ECD

and

are

thus

relatively

inexpensive

to

implement

Conclusions

Regulators

and

managers

require

data

on

PCBs

and

OCPs

concentrations

in

environmental

media

to

assess

water

quality

food

contamination

and

to

infer

possible

biological

effects

Indeed

the

global

assessment

of

the

success

of

the

Stockholm

POPs

convention

assumes

a

chemical

measurement

capability

in

all

UNEP

regions

which

will

deliver

data

on

concentrations

in

key

media

-LSB-

-RSB-

The

analytical

methodologies

discussed

here

refer

to

an

analytical

system

encompassing

information

on

the

collection

and

storage

of

samples

the

procedures

used

to

extract

isolate

concentrate

separate

identify

and

quantify

POPs

residues

in

samples

as

well

as

specific

quality

control

and

reporting

criteria

All

aspects

of

this

system

must

be

in

operation

for

POPs

to

be

analyzed

and

reported

The

chemical

analytical

methodology

for

the

determination

of

PCBs

and

OCPs

is

a

mature

area

within

environmental

analytical

chemistry

as

a

result

of

research

and

development

over

the

past

years

Basic

steps

in

the

quantification

of

OCPs

and

PCB

congeners

have

hardly

changed

in

the

past

years

Analytical

methods

for

the

determination

of

OCP/PCBs

in

foods

soils

sediments

fish

birds

mammals

-LRB-

including

human

milk

and

blood

-RRB-

are

available

and

could

be

implemented

at

relatively

low

cost

in

developing

countries

However

access

to

modern

capillary

GC

equipment

with

either

electron

capture

or

mass

spectrometry

-LRB-

MS

-RRB-

detection

to

separate

and

quantify

PCBs/OCPs

is

required

in

order

to

conduct

the

analysis

and

to

take

part

in

regional

and

international

intercomparsons

In

general

ELISAs

are

very

useful

tools

for

the

rapid

assessment

of

PCB/OCPs

contamination

especially

in

areas

of

former

heavy

use

They

are

particularly

well-suited

to

laboratories

in

developing

countries

which

may

have

access

to

spectrophotometric

equipment

but

not

to

GC

instrumentation

Existing

analytical

methods

for

PCB/OCPs

can

determine

over

individual

components

at

low

ng/g

concentrations

in

many

environmental

media

using

high-resolution

capillary

GC

ECD

However

the

number

of

certified

values

for

OCP/PCB

congeners

in

certified

reference

materials

is

more

limited

-LRB-

approximately

PCB

congeners

and

OCPs

in

NIST

cod

liver

-RRB-

At

a

minimum

the

OCP/PCBs

for

which

there

are

certified

values

in

readily

available

CRMs

should

be

determined

-LRB-

approximately

-RRB-

With

this

number

of

analytes

the

information

would

be

useful

for

both

regulatory

actions

as

well

as

for

source

identification

using

multivariate

analysis

or

other

fingerprinting

methods

Interlab

comparisons

of

POPs

analysis

over

the

past

ten

years

have

shown

that

availability

of

accurate

analytical

standards

is

a

fundamental

requirement

of

an

analytical

program

designed

to

quantify

trace

organic

contaminants

such

as

POPs

Agencies

such

as

GEF

and

UNEP

Chemicals

should

give

top

priority

to

ensuring

that

certified

analytical

standards

are

available

to

all

labs

on

a

continuing

basis

Quality

assurance

programs

are

critically

important

for

demonstrating

the

performance

of

analytical

methods

for

POPs

within

a

lab

and

between

labs

QA

requirements

for

PCBs/OCP

analysis

are

well

known

and

include

the

use

of

certified

reference

materials

field

and

laboratory

blanks

the

use

of

quality

control

charts

to

monitor

long-term

lab

performance

participation

in

interlaboratory

studies

and

the

use

of

guidelines

for

sampling

and

analysis

Determination

of

PCBs/OCPs

requires

the

analysis

of

blank

samples

because

of

the

ubiquitous

nature

of

these

contaminants

If

blanks

are

significant

-LRB-

for

example

averaging

greater

than

of

the

average

level

of

total

PCBs

-RRB-

then

blank

correction

should

be

carried

out

As

a

routine

measure

spiking

surrogate

recovery

standards

into

each

sample

provides

useful

information

on

losses

of

analyte

from

the

extraction

step

onwards

However

no

single

PCB

or

OCP

can

be

representative

of

all

the

organochlorines

being

determined

and

thus

recovery

correction

should

be

performed

with

caution

Isotopically

labeled

surrogates

are

ideal

for

the

quantification

of

PCBs

and

many

OCPs

via

LRMS

and

HRMS

the

application

of

isotope

dilution

techniques

can

correct

for

the

recoveries

of

these

surrogates

Detection

limits

depend

not

only

on

the

analytical

method

used

but

also

on

the

sample

size

and

QA

considerations

e.g.

on

information

available

from

blank

or

control

samples

and

recovery

studies

Detection

limits

should

be

calculated

as

described

by

US

EPA

or

by

IUPAC/ISO

methodology

Comparison

of

detection

limits

for

widely

used

instrumentation

for

POPs

with

action

limits

for

POPs

in

food

and

tissue

residue

guidelines

suggests

that

current

GC

ECD

and

GC-MS

analytical

methodology

for

PCB/OCPs

can

meet

and

exceed

these

limits

in

some

cases

by

orders

of

magnitude

Some

emerging

new

analytical

techniques

such

and

fast

GC

using

GC

ECD

may

be

well-suited

for

use

in

developing

countries

in

the

near

future

given

their

relatively

low

cost

and

their

ability

to

provide

high-resolution

separations

of

OCP/PCBs

Procedures

with

low

environmental

impacts

-LRB-

microscale

low

solvent

use

etc.

-RRB-

may

be

particularly

well-suited

to

developing

countries

where

analytical

budgets

are

small

and

product

delivery

times

are

lengthy

Thus

strategies

must

be

considered

that

will

allow

improved

techniques

to

be

adopted

by

such

labs

Electronic

supplementary

materials

Below

is

the

link

to

the

electronic

supplementary

material

Table

-LRB-

DOC

kb

-RRB-

Table

-LRB-

DOC

kb

-RRB-

Table

-LRB-

DOC

kb

-RRB-

pcbs organochlorines pesticides pops review analysis extraction

gc–ecd
gc–ms
sample preparation and qa/qc