chlorinated dibenzodioxins and dibenzofurans

C h e m o s p h e r e , Vol.17, No.5, P r i n t e d in Great Britain

RAPID

pp 889-903,

PHOTOLYTIC

1988

DECOMPOSITION

BROMINATED/CHLORINATED

Federal

CH-8820

OF B R O M I N A T E D

DIBENZODIOXINS

Hans-Rudolf Swiss

0 0 4 5 - 6 5 3 5 / 8 8 $3.00 + .OO P e r a a m o n Press plc

AND

AND D I B E N Z O F U R A N S

Buser

Research

W~denswil,

Station

Switzerland

ABSTRACT

Rapid

photolytic

dibenzofurans sunli g h t ing

compounds.

chemi c a l the

with

laboratory ted

that

cautions

(PCDDs)

and

light

are

major

and of

in

compounds order

solution

showed

exposure.

compounds

likely

has

be

In

are

environmental

full

and

summer

that of c o r r e s p o n d -

this

was

way, from

Solid

phase

surfaces

under

of

the

consequences

was

compounds

some d e c o m p o s i t i o n

photochemical

photo-

photolysis

sunlight

the

provided

reductive

polychloro-

formed

Exposure

obtained

The

under

observed

analogues.

hours.

to m i n i m i z e

so far unknown.

congeners.

on quartz

can

than

pathway

(PCDFs)

dibenzodioxins

solution

faster

of

data

cations

much

bromo/chloro

analytical

halogenated are

I min,

brominated

the

bromo/chloro

photochemical

in h y d r o c a r b o n

taken

and

hydrocarbon

dibenzofurans the

bromo/chloro

half-lives

reliable

bromo

dilute

to lower

decomposition

bromo

of

in

as low as

The

leading

dibenzodioxins

slower

observed

with h a l f - l i v e s

chloro

debromination

of

decomposition

was

but

indica-

suitable

behaviour but

to

of

actual

prethese impli-

INTRODUCTION

Polychlorinated much

scientific

mental these rial

dibenzodioxins and

contaminants compounds chemicals

are they

public and

some

varied. are

(PCDDs)

and d i b e n z o f u r a n s

attention. of

them

Apart

also

These are

from

formed

precursors.

889

extremely

being in

compounds

(PCDFs) are

toxic

contaminants

combustion

have attained

known (I). in

processes

The

as

environ-

sources

certain from

of

industsuitable

890

Bromo

and b r o m o / c h l o r o

ty as the chloro as

thermolysis

an

accidental

tional

products fire

PCDDs

PCDFs.

chlorinated

halogen

compounds

are

brominated

thought

compounds

mixed

of leaded

to

entering

flame

be

retardants

such

a

one

of

the

both

scavenger

compounds

(dichloro-

and d i b r om o e t h a n e )

and

PCDFs

have

been

associated

and

some

other

bromo

compounds

have

been

identified

(10-12),

bromo

and

and d i b e n z o f u r a n s

have not yet been a c t u al l y

However,

bromo/chloro

dibenzodioxins

ash

incinerators

(13-15);

from

(pyrenes)

were

identified

PCDDs

and

PCDFs

about

the

1940-50s

with

the

use

of

and

other

could

and

would

from

the

dation

of

by sunlight

and

PCDFs

bromo

(19,20).

obtained

We

bromo

halogenated pounds

were

pected

and

behaviour

found. later

of

Photolysis

of

so

far

the

Photochemical

bromo

a

and

In

on

paper

bromo/chloro

since

correlate increased

Switzerland

increase

analysis

of

halogenated

route

also

environcompounds

sources.

of these

of

aromatic

less

the

loss

The

compounds,

now

high

a

year

with

The

although

rapid

artificial

light

only

instability

and

different

chloro

compounds

exceptional

dibenzodioxins

including

containing and

chemicals

photodegra-

photolytic

of the bromo the

of

compounds

attention

solution

over

decomposition this

compounds

the in

similar

fly

(14,16).

and present

reported

standard after

and

dehalogenation.

was

indication

when

reanalyzed

confirmed.

via

attained

(PBBs)

aromatic

in

used.

chlorinated

has

a The

stability

potential

to proceed

first

was

one

emissions.

environment

of additional

and p r e c a u t i o n s

is known

compounds

compounds

However, gasoline.

PCDDs

aromatic

detected

processes

of such previous

represents

the

of

or absence

polybromobiphenyls

aromatic

time.

use

in

from

dibenzodioxins

samples

compounds

on the e n v i r o n m e n t a l

compounds

of

that and

found

concentrations

in the

combustion

is

in a u t o m o b i l e were

of

halogenated

Whereas

bromo/chloro

aromatic

presence

bromo/chloro

measureable

levels

other

importance

techniques

degradation

of

about

depend

environment.

PCDDs

chloro

and

traffic

the r e l a t i v e

finding

Decomposition

of

for the p r e s e n c e

the a n a l y t i c a l

PCBs,

since

in

stable

and bromine

involved.

in e n v i r o n m e n t a l

increased

to

other

bromo and b r o m o / c h l o r o

environment The

production

countries

samples

the

incineration

in a u t o m o b i l e

reveal

actual

in

other

from addi-

environmental lead

situation

and

reported

these

The

to

dibenzofurans

in fly ash and

(17,18).

increased

municipal

occurred mental

are

and

of

chlorine

are

samples

investigated.

PCDFs.

a

toxici-

identified

of

can

lead

Such

usually

in

sources

and may

products.

where

and

processes

PCDDs

were

occurrence

systematically

process

halogenated gasoline

the

combustion

including

in

are of similar

such c o m p o u n d s

however,

has not yet been

elements

including

the c o m b u s t i o n

and d i b e n z o f u r a n s

Very r e c e n t l y

Otherwise,

Chlorine

aromatic

additional

from

congeners

processes

and

(2-6).

(7-9).

halogenated

Combustion

dibenzodioxins

analogues

was

comsus-

photochemical

dibenzofurans

is

891

pointed and

out.

Emphasis

elucidation

environmental

listed from

investigated.

in

Table

a previous

because

tions

A,

The

and

and

halogenated

prepared

of r e a c t i o n

Potential

C

products

analytical

toxicity

which

Compounds

to yield

of

these

their

and

sources

dibenzofurans

were

light.

(1,2,3,4-tetra-BDD)

All

these

with

compounds.

ng/~L

and

Soluof

the

the residues

range

(see

contained

as a p h o t o c h e m i c a l

very

to m i n i m i z e

solutions

to d r y n e s s

solutions

available

out

combined

stock

in the

were

(2,3,7,8-

were

carried

were

from

were brought

concentrations from

were

between

made

are

2,3,7,8-tetrachlorodi-

compounds

compounds

c o m p ar i s o n s

or nonane,

protected

and

and of

the e x p e r i m e n t s Several

each)

were

bromination

amounts

~L

in i-octane

used

2,3,7,8-tetrachlorodibenzofuran

small

solutions.

(500-1000

tetrabromodibenzodioxin

I:

and

compounds

dibenzodioxins

via

and to a l l o w direct

solutions

Table

pathways.

out.

halogenated

only

high

of dilute

in toluene

redissolved I).

The

Mixed

Because

work B

compounds

I.

study

of their

volumes

analytical

are pointed

(2,3,7,8-tetra-CDD)

tetra-CDF)(21).

small

study was on i d e n t i f i c a t i o n degradation

SECTION

benzodioxin

and

in this possible

consequences

EXPERIMENTAL

Compounds

of

Table

1,2,3,4-

standard.

investigated Solution, A

conc. B

1,2,3,4-tetra-BDD 2,3,7,8-tetra-BDD 2,3,7,8-tetra-BDD

5

2 I I

1,2,3,4-tetra-CDD 2,3,7,8-tetra-CDD

2.5 2.5

1,2,3,4-tetra-CDF 2,3,7,8-tetra-CDF 1,2,7,8-tetra-CDF

2 3 0.3

Compound

1-bromo-2,3,7,8-tetra-CDD dibromo" " " 1-/4-bromo-2,3,7,8-tetra-CDF dibromo-tetra-CDF

in ng/pl C

5

I

Source

a b b c d

I

e c f

5

g

10

g

a) O. Hutzinger, U n i v e r s i t y of Bayreuth, Bayreuth, FRG; b) R a d i a n Corp., Austin, Texas; c o u r t e s y W. Rotard, B u n d e s g e s u n d h e i t s a m t , Berlin, FRG; c) C. Rappe, U n i v e r s i t y of Umea, Umea, Sweden; d) G i v a u d a n Ltd., D~bendorf, Switzerland; e) Y. Masuda, Daiichii College of P h a r m a c e u t i c a l Sciences, Fukuoka, Japan; f) impurity from 2 , 3 , 7 , 8 - t e t r a - C D F ; g) see r e f e r e n c e 21.

892

S unli g h t

exposure

small

quartz

about

40 mm

a volume

sunlight

of

as

zero

toluene), aliquot

zero

the

with

solvent error

and

than

were

for 72 hr. addition

This

inside

for

a

weather

period

possible.

B

left than

initial

small

All

the

were

a n a l y z ed

with

(more

the

surface Traces

with

as

98%

vacuum.

for

of

vials

recovered)

the

during

at W a d e n s w i l 10-20

hrs

solution

tip

vials.

Aliquots volume)

removed

of 25 ~ L with

to u n e x p o s e d

controls

of 2-~L were

of

of

solvent

500

ng)

by

eva-

by hand. a

thin

of the tip the

from

vials

light

flame-sealed.

operations.

photolyses.

quartz

as

keeping

these

similar

each

was

of the vials

vials

of J u l y - e a r l y though

Unexposed

not

vials

as

Pre-

photolytic The

6

used

25 ~ L

individual

The

negligible

under

screw-

2 m dis-

then

end

of

in

covers)

were p r o t e c t e d

the

of

from

showed

at

simul-

light

(about

were

at

sea-

in May.

50 mm 2) on the walls

were

The vials the

exposed

Aliquots

rotation

covered

],2,3,4-tetra-BDD

of

the

sky)

above

Evaporation

artificial

films.

in

m

out

Aliquots

material

solvent

(area

a concentration

protective

and axial

area

2-~L

analysis.

carried

(I mL

to

separate

solid

of

necks

to sunlight time

to

A

in

causing

comparatively

placed

heating of

narrow

than

and

450

were

light.

vials

as d i s p e r s e d

added

(30 s) under The

exposure

conditions

mixed

C was

gentle

vials.

horizontally total

were

glass

(I ng/~L

analyzed.

exposure.

were

laboratory PVC

imme-

small

(cloudless

solutions

laboratory

with

removed in

(GC-MS)

47o;

thereby

soft-glass

in

sunlight

during

I mg/hr

after

reproducibility

(latitude

open

and and

I%.

experiments

40 Watt,

deposition

experiments

composition exposed

midday

28-30°C.

compounds

(estimated

quartz

for a short

the

solution

in

film

the

liminary

into

samples

of

and

by v a c u u m

as

full

to a r t i f i c i a l

(Osram-L, The

of

resulted

dispersed

much

A

25 ~ L

porated

Some

(vertically)

exposure

solutions

vials;

of

until

analyzed;

i.d.)

standard

spectrometric

than

to

were

light

were

in were

in a vial syringe

placed

internal

better

Switzerland

(0.5 mm

Hamilton

were

exposed

The vials

was placed

subsamples

of 10 ng of 13C I 2 -2 ' 3 , 7 , 8 - t e t r a - C D D analysis.

for GC-MS

Sunli g h t

neck

from

separately was

to be less

I-2%.

lamps

after

narrow

a 25-~L

Two

were

tubing.

subsamples

protected

vertically

vials

placed

tance

with

60 min. All

were

temperatures quartz

exposed

fluorescent

and

W~denswil,

of the compounds

solution

caps

in

air

long

Solutions

quartz

of a s o l u t i o n

chromatographic-mass

standard)

was d e t e r m i n e d

Expos u r e

15 and

controls.

controls

exposed

The

of less

5,

for gas

July

tip,

250 ~ L

periodically

refrigerated

were of

taneously.

of

2,

solution.

10 ng 1 3 C 1 2 - 2 , 3 , 7 , 8 - t e t r a - C D D

exposure

end

level)

a

for

used

in

5x3 mm d i a m e t e r

About

removed

analyte/internal

The vials

from

a flame-sealed

exposure

with

kept

was

compounds

300 ~ L .

25 ~ L

spiked

ratio

with

exposure

diately

Two

long,

the

prepared

of around

subsamples

vials,

of

vials

dewere

August

identical were

kept

893

as

zero

exposure

controls.

2,3,7,8-tetra-CDD pL)

of

was

used

i-octane

GC-MS

and

for G C - M S

analysis.

Finnigan

4000 50

25-m

SE54

fused

was

to

160°C,

All

eV),

used. was

were

compound

50-750,

Table

and 1.5

2:

Table

2).

The

were

large as

Some

samples

spectrometric

used

for m o n i t o r i n g GC-MS

A

13C12of

2-~L

an

i.d.)

Incos

with

100

aliquot

out

with

a

ionization

datasystem. 1.5-m

A

retention

made.

The

isothermal,

HRGC

20°C/min

300°C.

with

while

were

a

were

2 min

(MID).

two

chosen

for

compound

to 24-

monitor

sufficient

full-scan

(m/z

identification.

dibenzodioxins

(quantitation

to

retaining

concentrated

halogenated

18-

(M + or s a t e l l i t e )

were

still

and

Three

ions

descriptors

analyses

carried

electron-impact

detection

analysis

ions

and di-

underlined)

Ions m o n i t o r e d (m/z Dibenzodioxins Dibenzofurans

498, 418, 340, 262, 320, 286, 398, 478,

500 420 342 264 322 288 400 480

were

calculated compared

percent

were

made

lute

quantitative

first-order

was

i-octane)

used

MID

tetra-BDDs/BDFs tri" " di" " mono" " tetra-CDD/CDF tri" " bromo-tetra-CDD/CDF dibromo-tetra-CDD/CDF

as

10 ng (total

30 ~ L .

and

80°C,

at

possible

mass

in M I D

mm

in

multiple-ion time)

334

pressed

about

the

(0.32

isothermal

332,

were

opened,

4 portions

analysis

follows:

13C12-2,3,7,8-tetra-CDD

values

were

with to

in

(2-pl

as

compounds

sensitivity.

(m/z)

column

then

using

Compound

Results

vials

chromatograph

injections

s cycling

benzofurans

operating

programmed

as m a n y

GC-MS

Mega

capillary

analyzed (0.6

s/scan)

Ions

(HR)

Erba

to 300°C,

(see

simultaneously precision

Carlo

On-column

5°C/min

the

extracted

concentrated

instrument

a

temperature

samples

extract

silica

ion d e s c r i p t o r s per

the

exposure

residues

analysis.

GC-MS

(EI,

column

After

the

High-resolution

mode

gap

added,

via

to

analyte

for d i f f e r e n t data

area

those

of

ratios the

remaining

MID

response

is r e p o r t e d .

482 402 324 246 304 270 382 462

484 404 326 248 306 272 384 464

analyte/13C]2-2,3,7,8-tetra-CDD;

zero versus

exposure time

of d i f f e r e n t Half-lives

of

controls exposure.

congeners

(tl/2)

were

kinetics -in

(Cl/C0)=

kt

tl/2

= in 2/ k

and

(100%) No

and

the ex-

corrections

hence

no abso-

estimated

assuming

894

where

cl/c o

time

is

t, and

the

k the

tion p h o t o l y s i s

RESULTS

rate

and

under

sunlight

as thin

bromo/chloro

solid

films.

in all

creased

was

light

intensity

(23,24;

geners.

see

shown

for

exposure the

solu-

tetrabromo around

I-2 min).

single

peak

a

analogy

to

are

expected

not

estimated longer

the

to be

at around

than

that

(2,7- and/or

Reductive

the

a

(23,24).

debromination

In

this

less The

brominated

way

data

the

and

strong

to

be

major

indicates

high

if

final

dibenzodioxin

not

products

of

formed

pre-

for

exclusive

(DF).

expected and

the

these

in

2,3,8-tri-BDF

again

and

a

were

rather

experiments

formation

(DD) and d i b e n z o f u r a n

con-

tri-BDFs

9 min,

higher

under

estimated

were

and

congeners

observed

chloro

decomposition

with

2:2

type

observed.

pathway

carbon-ring

from

the

was

these

decomposition

2,3,7,8-substituted likely

indicating

were observed.

C6H3 +) were

observed

formafurther

brominated

expected)

brominated

previously

2,3,7-

in-

with

fast

preliminary

the

higher

The

considerations

at around

75 ion,

to

eluting)

two tri-BDFs time

m/z

very

The

In

lower

rather

(2,3,7-tri-BDD

due

with

l-isomer)

half-lives

the di-BDFs

compound.

toxic

the

compounds

The

analogy

com-

Accelerated

subsequently

(earlier

C as a

this

experiment.

of

B showed

chloro

3).

1,2,4-tri-BDD

half-life (likely

(25). of

was

of

B and

possibly

the

nonane) dispersed

for

eluting)

in

retention

not

species.

unsubstituted

same

half-life

From

Table

are

(later

positions

longer

tri-BDD

the

the

2,3,7,8-tetra-BDF

the

appears

(see

which

A,

observed

1,2,4-isomer

in solution

parent

from The

stable

a

2,8-isomer;

predominantly

lateral-positions.

The

those

single

is the

and m o n o - B D D

with

min

of

compounds

solutions

was

photolysis

part

1,2,3-tri-BDD

separated

2 min,

of

2,3,7,8-tetra-BDD

latter

observed.

situation

2-3

was o b s e r v e d

From

to

of

(i-octane,

the same

added

of

lateral

I).

compounds

(half-lives only

of

indicating di-BDD

was

solution

decomposition

solution

with

proceeding

the

the

in h y d r o c a r b o n

decomposition

formed

at

but

geners.

after

(22).

photochemical

decomposition

congeners

Scheme

min,

Furthermore,

three

be

was

et al.

hydrocarbon

half-lives

amounts

compounds

11

fast

in

during

tri-BDD

smaller

around

very

during

brominated

debromination

to

remaining

kinetics

and PBDFs

significant with

ferential

be

slower

apparent

The major

concommitant

occur

compound

by N e s t r i c k

1,2,3,4-Tetra-BDD

solutions

tion of lower degraded.

showed

standard;

decomposition

of PBDDs

compounds

but much

photochemical

di-BDD

the

First-order

tetra-CDDs

photolysis

experiments

bromo

All

of

AND D I S C U S S I O N

Preliminary

to

amount

constant.

of several

Sunlight-induced

pound

relative

and

chloro can

be

and

from

compounds expected

substituted of

to the

these

conditions

conlower were

895

Scheme

I:

Br Br~O~ fasy ~r O"~///m slOW~Br Br O

Br Br

Br

di-BDDs I ono BDD(s)

:

DD

I

further degradation Sunlight-induced

p h o t o l y s i s of PCDDs and PCDFs

The p h o t o l y t i c h a l f - l i v e s to

that

of

Tetra-CDD

first-order

1,2,3,4-Tetra-CDD in the order

of

appears

380

by

Nestrick

et

in the

decomposition

two b r o m o a n a l o g u e s .

case

of

half-lives CDDs,

no

the of

the

much

same

(22).

rates Very

and

more.

of

solution

an

more

stable

these

two

rather

slow

the

half-life was

re-

variation

between

the

observed

with

with

the

tetra-

was

found.

of b r o m o / c h l o r o d i b e n z o d i o x i n s

with

was

situation

Sunlight-induced

Solution

than

min.

2,3,7,8-tetra-CDF

amounts

in h y d r o c a r b o n

14

isomers

greater

isomers

2,3,7,8-

of

estimated two

decomposition

and

3).

f o r m a t i o n was observed.

The f o r m a t i o n of only small

photolysis

(about

an

these

chloro

from

1,2,3,4-

(Table

half-life

is a much

tri-CDD

Different

between

with

with

there

(about I%)

A

estimated

observation

between little

difference

data

solution

-CDFs can be d i r e c t l y c o m p a r e d

with

Apparently

tetra-CDFs

180 min

large

The

al.

three

from

kinetics

to be

min.

ported

In

of the t e t r a - C D D s and

1,2,3,4-tetra-BDD shows

in h y d r o c a r b o n

3%) of tri-CDFs was observed.

and d i b e n z o f u r a n s

solution

C contained

mixtures

2,3,7,8-tetra-CDD

showed a h a l f - l i f e

around

and

of mono-CDF

2.5 min

Apparently

the

(21).

and d i b r o m o - t e t r a - C D D s I ,2,3,4-Tetra-BDD

(see Table

previous

values.

profound

i n f l u e n c e on the d e c o m p o s i t i o n

additional

3) w h i c h

and

in

-CDFs

this

is in a g r e e m e n t

compounds

present

rate of this compound.

here

along

solution with the have

no

896

Table

3:

Sunlight-induced

photolysis

dibenzofurans

i-octane

in

of

Rel.

halogenated

amounts a

dibenzodioxins

(% r e m a i n i n g )

exposure Compound

Sol.

Control

2

5

A "

100 <0.05

64 27

"

" " "

<0.05 <0.05 <0.05

1,2,3,4-tetra-CDD 2,3,7,8" "

" "

100 100

101 92

1,2,3,4-tetra-CDF 2,3,7,8" " 1,2,7,8" "

" " "

100 100 100

101 101 100

1,2,3,4-tetra-BDD 2,3,7,8" " tri-BDDs di" mono-"

B " " " "

100 100 ~0.4 < 0.4 <0.2

56 30 29 20 < 0.2

2,3,7,8-tetra-BDF tri-BDF di"

" " "

100 0.5 0.5

"

0.5

1,2,3,4-tetra-BDD 1,2,4-tri" 1,2,3-tridi-BDDs mono-BDD

mono-" 1,2,3,4-tetra-BDD

C

100

2,3,7,8-tetra-CDD I -bromo" dibromo" bromo-tri-CDD tri-CDD

" " " " "

2,3,7,8-tetra-CDF I-bromo" 4-bromo" dibromo" bromo-tri-CDF tri-CDF

" " " " " "

a)

peak

control

area

bromo-PCDDs, tetra-CDD and

accuracy,

not

-CDF and

estimated

33 53

0.8 40

<0.05 2

11

9 12 0.8

3 52 17

<0.1 33 76

104 82

95 44

91 5

380 14

102 104 103

92 95 95

80 84 94

180 220 600

3

18 1.6 44 25 I

0.2 <0.4 25 73 27

<0.2 <0.4 < 0.4 10 53

2 0.8 8 16

<0.5 15 116 1

<0.5 <0.5 129 31

<0.5 <0.5 4 71

0.7 2 9

<0.1

2.5

139 1 35 10 4 3

180 82 3 2 6

178 15 <0.1 0.5 17

151 <0. I <0.I <0.I 3

100 203 118 140 2 <0.1

514 48 55 16 10 2

691 I 2 <0.I 9 7

629 <0.1 ~0.I <0.1 3 18

444 <0.1 <0.1 <0.1 <0.1 22

to

to

accuracy

of

-CDF

reported

total

derived

2

90 0.5 0.5 0.5

standard

relative values

amounts

from

half-lives

4

MID-response;

respectively; the

(200)

internal

different

and

values

I

13C-tetra-CDD

for

compounds,

relative b)

Half-life(min)

100 1 67 18 3 0.5

tri-CDD

parent

respectively;

0.5

60

27

corrected

-BDFs

15 38 29

Estimated b

(min) 15

63

relative

bromo-PCDFs,

and

tri-BDDs

tetra-BDFs, ted

ratios

samples,

4 0.8 <0.1

and

few

±50%.

of

data

of

and

values to

mono-,

tetra-BDDs points

of

2,3,7,8-

of

diand limi-

897

In

case of the b r o m o / c h l o r o d i b e n z o f u r a n s

than

I min)

of

the mono-

f o r m a t i o n of a d d i t i o n a l and f i n a l l y CDF.

of

the

predominant

loss of c h l o r i n e

bromo-tri-CDF

This

and d i b r o m o - t e t r a - C D F s

formed

decomposition

to

compounds

this

mixture

have

BDF.

The p h o t o l y t i c

be

into

about

less

than

results

in

PCDFs.

the

same

is

half-life

3% the

The

(half-lives

observed

less

resulting

in the

to be m u c h more

stable

t o g e t h e r w i t h a small a m o u n t of tri-

reaction

the

is a very m i n o r p a t h w a y

pathway

bromo/chloro

was

2,3,7,8-tetra-CDF which appears

is the m a j o r p r o d u c t o b s e r v e d

Apparently

tuents;

fast d e c o m p o s i t i o n

of

relative

to

the

the

preferential

I-

half-life

loss

and e s t i m a t e d

and

bromo-substi-

from the amount loss

of

conversion

bromine. of

these

4-bromo-2,3,7,8-tetra-CDF

(about

0.5

of 2 , 3 , 7 , 8 - t e t r a - C D F

min)

in this

as

in

2,3,7,8-tetra-

s o l u t i o n was around

90 min.

The

same

The

small

posed

II).

behaviour

amounts

fast

further

be

general

(half-life

decomposed

reaction

200 with

compounds Figure their

Scheme

min, the

with

the

I document conversion

about

observed

2 min)

(half-life

The p h o t o l y t i c

around

was

of d i b r o m o - t e t r a - C D D s

half-life somehow

bromo

into

bromo/chloro

was

longer again

photolysis

dibenzodioxins.

not separated)

1-bromo-2,3,7,8-tetra-CDD,

4 min)

substituents

rapid

the

to

2,3,7,8-tetra-CDD

of 2 , 3 , 7 , 8 - t e t r a - C D D much

bromo-PCDDs

the

to

around

for

(3 isomers,

than

in

in this solution

debromination

at

in

peri-position.

of

the

2 , 3 , 7 , 8 - t e t r a - C D D and

bromo-PCDDs

were decomwhich (see

solution A.

The

high

The

then

Scheme

appears

to

predominant

rate

even

for

chromatograms

and

2,3,7,8-tetra-CDF,

bromo-PCDFs

in and

respectively.

II:

Br Br cIIf(~"T'°~(~'~lcIA __ fast cIr~------'~o-v~cI fast cI

c

c,

Br slow

I

-CI

o

cI

o©c,

I

slow I-CI

slow ~ - CI T

slow 1 further degradation

898

Photolysis s olut i o n

This

o__ff h a l o g e n a t e d

with a r t i f i c i a l

experiment

bromo tory

was

carried

and b r o m o / c h l o r o light

reason

as

the

it

(5 hours

tions

A,

and

These

conditions

sample

B

All

C

of

the

were

than

those

precautions

were

days).

The

of these

under

to m i n i m i z e

quartz the

the

and

teristics

are more

here

to

sunlight expected

(5-8%)

p rodu c t s

around

normally

encountered

during

are

taken

(prevention

indicates

compounds,

was

however,

(half-lives in the

low decomposhowed

~8

same

The results

order

as

The

in case

and

indicate

conditions

more

days).

-CDFs

sufficient

provided

suitable

exposure.

dibenzodioxins

A

the

the

compounds

are

given

from

and d i b e n z o f u r a n s

probably

of

of

for

26-35

hrs.

Only

tribromo pathways

so far have

rates

as

films

in

4. More

variation

in

because

film

hrs. of

10

or

2,3,7,8-

was

20

Compared

hrs with

and

reported

previously

tetrabromo

compounds

very

small

be

amounts were

involved.

not been detected.

(1%)

of

observed, However,

charac-

observed. exposure the

Also All with

situation

1,2,3,4-tetra-CDD

3

compounds)

thin

to reproduce.

controls

was

the

may

vial

as

are d i f f i c u l t

after

35-300

finding

found

to

the u n e x p o s e d

relative

similar

dispersed

in Table

vial

decomposition range

was

degradation

products

some

in the

(predominantly

additional chemical

showed

reversed.

uniformity)

in the data

photolysis

decomposition

half-lives

with

was

half-lives

so l u t i o n

Solulamps.

e.t.c).

analytical

rates

compounds

estimated

decomposition.

dibromo-2,3,7,8-tetra-CDDs

of h a l o g e n a t e d

experiments

(area covered,

variation

chloro

this

Preliminary

fluorescent

79-93%

days).

light

exposed

decomposition

more

in

photolysis

normal

vials.

laboraFor

films

of

vials

and

(half-lives~9

are taken

results

only

compounds

Bromo-

stability

The

tetrabromo at

ordinary

of

from

at 93% or more which

recovered

at 80-86%

light

use of amber vials,

recovered

were

to

if any

some

precautions

solid

little

hrs

behaviour

procedures.

in quartz

severe

photolytic

diffuse

very

72

not

provided

exposures.

Sunlight-induced

and

be more

susceptibility

recovered

in glass

under

preparation

should

and

sunlight

and d i b e n z o f u r a n s sample

showed

procedures

i__n h y d r o c a r b o n

photochemical

for

(half-lives ~ 2 8

photolytic

the

exposed

tetra-CDDs/CDFs

sition

investigate

during

exposure)

sun- or daylight,

decomposition

to

exposed

dibenzofurans

were

preparation

of direct

occur

were

experiments

out

and

light

dibenzodioxins

might

samples

dibenzodioxins

laboratory

(22). with some

Somewhat estimated

photolysis

indicating additional

that photo-

899

r-, I-I

p,.

C::I C~

¢q I¢,,1~,

I-I

I~ C~

_i~i

..

0.4+,

C4 ,,,.,+

I'-I

,~ m

~0 p--

l cO " t~

2 P..+ E

' <~ B +...i

m

~

O

m

m

£',,I I

0 N

!

2\ ~'

~

-,'-,

0

.+5+ -H

Y

~

p-!

I-" I CO

I

,

¢¢

J i

-,-~

~

~

0

r~

E

-,-t

3

,./

m

i

c'-q r~

O

I-I

Y

~4

-~--

~

~ ~

C3

C)

0

~

p-

0

LI_ '+-'

I--

¢_)

I

p,,.. +.'+O

b~

m

¢0

~

I-I

'-~ {1}

0

C~

o~2 I.I_ I-I O~ reo

O

-\

+,,,

+/

r-,

'7

I

p,_ I

r~ I

+~

-H

"0

0

0

0

O

~

•

i

8 Y

-\

0

.~ ~ •.,.-.+ ..-i

I

O

~q

I-.I p~ O}

/

,,-+

0

-,~

i

i.-+

8

e~ i-i

O

~

~

-~

0

i

~

0

q3 >~

4-} <1}

0 ,z~

0 -,-+

900

Table

4:

Sunlight-induced dibenzofurans

photolysis

dispersed

o_~f h a l o g e n a t e d

as

solid

Rel.

dibenzodioxins

films

amounts a

(% r e m a i n i n g )

exposure Compound

Sol.

1,2,3,4-tetra-CDD

and

Control

(hrs)

10

20a

Estimated

20b

half-life c

A+B

100

85

76

84

65

"

100

98

91

101

300

1,2,3,4-tetra-CDF

"

100

90

82

90

95

1,2,7,8-

"

"

"

100

86

64

73

35

2,3,7,8-

"

"

"

100

93

84

94

120

"

100

60

51

63

26

100

67

52

77

32

77

35

2,3,7,8-

"

"

I ,2,3,4-tetra-BDD 2,3,7,8-

"

.

.

.

.

2,3,7,8-tetra-BDF

"

100

60

53

1,2,3,4-tetra-BDD

C

100

12

13

2,3,7,8-tetra-CDD

"

100

117

100

1-bromo-

"

"

167

113

105

30

dibromo-

"

"

9

I

3

12

"

2

0.5

2

bromo-tri-CDDs

7 b)

2,3,7,8-tetra-CDF

"

100

290

212

b)

1-bromo-

"

"

227

105

115

b)

4-bromo-

"

"

134

23

35

dibromo-

"

"

139

25

35

bromo-tri-CDF a)

peak

"

area

control

bromo-PCDDs, tetra-CDD of

The

and

solution

C)

indicating

the

was the

of

deposition tion

tri-CDD

accuracy,

of

10-

and

techniques

with

pathway

1,2,3,4-tetra-BDD with

phase and

the

photolysis 20-hr

homogenity will

solid

of

the

respectively;

b)

values

in

-CDFs;

c)

accuracy

is m o r e

of

7

compounds this

This on

of

derived

(solid

the

of

2,3,7,8because from

half-lives

few

±50%.

films

from

and

-CDF

Similarly,

somehow

larger

the than

A+B.

to v a r i a t i o n may

to

2,3,7,8-tetra-CDD

was

and

values

estimated

photolysis.

hrs)

solution

subject

data.

not

compounds

solution

from

standard

relative

and

(half-life

improve

internal MID-response;

reported

formation as

films

exposure

hopefully

-CDF

bromo/chloro

concurrent

reaction

0.8

different

estimated

the

b) 10

13C-tetra-CDD and

compounds,

of

0.5

for

bromo-tetra-CDDs

larger

solid

the

parent

limited

same

experiment

Apparently some

of

to

corrected

decomposition

decomposition in

CDF from

points

photolytic

relative

not

bromo-PCDFs,

formation

data

ratios

samples,

0.7

(hrs)

be

due

surface.

situation.

The

as to

indicated variations

by in

Different

deposi-

difference

between

901

the

estimated

half-life

tions A+B and C (7 and ce of

non-volatile

solution

C.

Such

pronounced more

not

1,2,3,4-tetra-BDD

26 hours,

sensitizing

compounds

influence

sample

leads

of

handling

respectively) compounds

or

remain

the

may

here

than

in

to

fully

account

in

solution

(evaporation,

to g r e a t e r data v a r i a t i o n

expected

in

for

may be due

solid

film

photolysis. from

in s o l u t i o n

the

solid

films

as

and

the

solu-

influen-

impurities

may

have

Additionally vials)

photolysis.

differences

from

to a larger

hydrogen-donors

extraction

than

the

a more

there

involved

is

which

This,

however,

with

the

observed

in

is

exposed

samples.

CONCLUSIONS

The m a j o r

photochemical

dibenzodioxins

dibenzodioxin

Additional

these c o m p o u n d s . position much

rates

under

rates

indications

that

carbon-rings

are

furans

A

lateral-halogens

loose

e x p e r i m e n t s was

like

bromine

significantly

brominated

consequences

losses of these analytes.

due

dures

be

to

brominated

compound

extraction,

There

are

chemicals

as

a

halogenated

phase

photolysis

detect, and

some

in

a

sample.

the

The use

photochemical

our

for the bromo

too

low values

during

conversion

added

to

from

should m i n i m i z e

of

to decom-

these

proce-

some

bromo/

of a p h o t o c h e m i c a l l y

standard

Because

Protection

-BDF were most prone congeners

especially

PCDFs.

aro-

in

behaviour.

a n a l y s e s may p r e t e n d

present

of

(PCDDs

in the range of 7-35 hrs.

2 , 3 , 7 , 8 - T e t r a - B D D and decomposition

dibenzo-

compounds

mixed

are

halogenated and

chlorinated

sample p r e p a r a t i o n and a n a l y s i s

Photochemical

into PCDDs

higher

There

other Solid

of

a few minutes,

compounds.

to this p h o t o c h e m i c a l

originally

position.

difficult

the

further

show high decom-

slower but still a p p r e c i a b l e

so r a p i d l y d e c o m p o s e d , compounds

from

to lower

are

film p h o t o l y s i s

of only

chloro

halogenated

leading

dibenzodioxins

with

pyrenes.

with h a l f - l i v e s

sun- or d a y l i g h t d u r i n g

congeners

to

exist

solid

those

all

likely

compounds

half-lives

and

leading may

then

in the

Bromo/chloro

bromo/chloro

compounds

these c o m p o u n d s are

may

which

corresponding

lost.

situation the

There are a n a l y t i c a l

chloro

with

the

model

direct

involved

sunlight of the

preferably

compounds

the

be

those

matic

for

natural

similar

and b r o m o / c h l o r o

may

with

reductive dehalogenation

and d i b e n z o f u r a n

than

preferably

PCDFs).

pathways

was

solution

In s o l u t i o n bromo and b r o m o / c h l o r o

higher

and

in h y d r o c a r b o n

and d i b e n z o f u r a n s

or u n s u b s t i t u t e d degraded.

reaction

samples

sensitive prior

to

c l e a n - u p and a n a l y s i s w o u l d be advisable.

also

potential

by s u n l i g h t

environment.

environmental

represents

The bromo and b r o m o / c h l o r o

photochemically

less

stable

in

consequences.

an i m p o r t a n t

the

route

compounds

environment

Decomposition

for their r e m o v a l

investigated

than

the

of

here are

chloro

some

from the likely

compounds

and

902

thus

may

be

atmospheric after

preferentially transport

deposition

surfaces vents

together

and

genated pounds

on

quired

light

a situation

analysis

for

bromo

bromo/chloro

and

be

samples

in

a

thought

grave

compounds

are e s p e c i a l l y

which

can

may

then

experiments

realistic

during or

even

be a d s o r b e d

photolysis

Additional

as

site

act of

as

the

with

environment

solhalo-

the

experiments

with

will

on

be

comthe re-

situation.

that

identification

especially

compounds

in our model

more

such

a deposition

situation

in

are

way

stable

samples may

in the

prone

this

more

of e n v i r o n m e n t a l

source

may

The

surface.

into this

is the

situation

mental

than

quartz

situations

to

compounds this

into the p h o t o c h e m i c a l l y

the

compounds

soil).

in

faster

surfaces

intriguing

may be c o n v e r t e d

be

that

certain source

additional

so

clean

on

to shed more

Especially

ted

a

adsorbed

(plants,

many

could on

in

combustion

surfaces

with

compounds

compounds

a

hydrogen-donors

adsorbed

degraded

from

for

lead

case

of

expected

bromo/chloro

PCDDs the

to

and

different

false

leaded

congeners

and PCDFs.

In such

halogena-

conclusions.

fuel

combustion

in situations

were

The were

environ-

to photolysis.

ACKNOWLEDGMENT

I

thank

several tute

O.

Hutzinger,

of the bromo

C.

Rappe,

and chloro

W.

Rotard,

compounds,

for W a t e r

Resources

and Water

for c r i t i c a l l y

reviewing

this manuscript.

Y.

Masuda

and

and J. Hoigne

Pollution

Control,

Givaudan

(Swiss

Ltd.

Federal

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(Received in Germany 9 January 1988; accepted 18 February

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