This
is
a
re­
typed
copy
of
the
July
12,
1985
memorandum
distributed
by
EPA
to
Solid
Waste
Branch
Chiefs
and
the
EPA
Regions.
The
original
electronic
version
of
the
memorandum
was
not
available.

Stamped
July
12,
1985
MEMORANDUM
SUBJECT:
Interim
Thresholds
for
Toxic
Gas
Generation
Reactivity
(
§
261.21(
a)(
5))

FROM:
Eileen
Claussen,
Director
Characterization
&
Assessment
Division
(
WH­
562B)

TO:
Solid
Waste
Branch
Chiefs,
Regions
I
to
X
Over
the
past
year,
we
have
received
many
inquiries
about
how
to
evaluate
wastes
for
reactivity
(
§
261.21(
a)(
5)).
We
have
initiated
a
number
of
studies
in
this
area,
and
expect
to
propose
a
quantitative
threshold
for
toxic
gas
generation
reactivity
in
December
of
this
year.
On
an
interim
basis,
however,
we
feel
strongly
that
wastes
releasing
more
than
the
following
levels
of
toxic
gas
should
be
regulated
as
hazardous
wastes:

Total
Available
Cyanide:
250
mg
HCN/
Kg
waste
Total
Available
Sulfide:
500
mg
H2S/
Kg
waste
The
available
cyanide
or
sulfide
should
be
measured
using
the
attached
draft
testing
methods.
Work
currently
being
done
on
the
agitation
and
waste
introduction
steps
may
result
in
significant
changes
in
the
subsequent
proposed
test.
However,
pending
the
conclusion
of
the
investigations,
we
recommend
use
of
this
draft
procedure.

I
have
attached
a
brief
outline
of
the
methodology
we
have
employed
to
derive
these
interim
thresholds.
Work
on
estimating
dispersion
factors,
however,
is
currently
in
progress.
Any
comments
or
suggestions
you
may
have
with
respect
to
either
the
draft
test
method
or
the
approach
to
establishing
thresholds
would
be
appreciated.

While
you
may
wish
to
be
flexible
in
your
application
of
these
levels
and
the
attached
test
method,
we
believe
the
levels
should
apply
in
most
cases.
Should
you
have
any
specific
questions,
please
call
David
Friedman
of
my
staff
at
FTS
382­
4770
(
202­
382­
4770).

cc:
Skinner
Lucero
Weddle
Corson
Friedman
Waste
Management
Division
Directors,
Regions
I
­
X
Hotline
Attachment(
s)
Attachment
Mismanagement
scenario:

A
truckload
of
waste
is
discharged
into
a
pit
containing
acidic
waste.
As
a
result
of
the
reaction
of
the
waste
with
the
acid,
a
rapid,
high
level
release
of
toxic
gas
ensues.
The
objective
of
the
characteristic
is
to
identify
those
wastes
which,
if
such
an
activity
were
to
take
place,
pose
a
hazard
to
those
persons
in
the
general
vicinity
fo
the
disposal
site.

Assume:

1.
The
truckload
of
waste
contains
6130
kg
of
waste
(
about
a
5
yd3
dump
truck
@
100
lbs/
ft3).
2.
The
velocity
of
the
wind
is
150
cm/
sec
(
3.4
mph).
3.
A
person
is
standing
10
meters
from
the
edge
of
the
disposal
pit.
4.
Exposure
to
concentrations
of:
HCN
above
10
mg/
m3
or
H2S
above
20
mg/
m3
pose
an
acute,
immediate
danger
to
human
health.
5.
The
area
of
the
pit
over
which
the
toxic
gas
is
generated
covers
225
m2.
6.
Before
reaching
an
exposed
individual
the
plume
of
contaminated
air
disperses,
in
a
linear
manner,
to
a
height
of
4
meters.

Then:

1.
The
minimum
toxic
gas
release
rate
that
would
have
to
be
present
to
exceed
the
danger
level
can
be
calculated
using
the
following
model.

2.
Total
available
Toxicant
level
then
that
poses
a
hazard
can
be
calculated
as
follows:

V
is
a
hypothetical
volume
of
air
to
which
an
individual
is
exposed.
Since
the
pit
is
15
meters
wide,
and
V
is
assumed
to
be
1.5
m
thick,
V
=
15
m
wide
x
4
m
high
x
1.5
m
thick
=
90
m3
T
is
the
time
it
takes
for
a
given
volume
of
air
to
travel
across
the
surface
of
the
pit
and
become
contaminated
with
toxic
gas.
Since
the
wind
speed
is
150
cm/
sec,
and
the
volume
slice
is
assumed
to
be
1.5
m
thick,
T
=
10
seconds
C
is
concentration
in
mg/
m3
of
toxicant
that
poses
a
danger.

A
is
the
amount
of
toxicant
contained
in
V
when
V
is
contaminated
to
a
level
that
poses
a
health
hazard.
A
=
V
x
C.
Since
a
given
"
slice"
of
air
takes
10
seconds
to
move
across
the
pit,
this
amount
of
toxicant
can
be
generated
over
10
seconds.

M
is
mass
of
waste
dumped
into
the
pit.

R
is
the
total
available
toxicant
necessary
to
pose
a
hazard
as
measured
using
the
attached
test
protocol.

=
Amount
of
toxic
gas
that
has
to
be
released/
length
of
test
Mass
of
waste
available
to
release
H2S
=
(
A)(
1800/
T)
(
M/
Percent
of
pit
area
available
to
contaminate
air
volume
in
any
given
unit
of
time)

=
(
V)(
C)(
1800/
T)
(
M/
10)

=
(
90)(
C)(
1800/
10)
(
6130/
10)

=
(
90)(
C)(
180)
(
613)

=
26.4
(
C)

=
264
mg/
Kg
total
available
cyanide
=
528
mg/
Kg
total
available
sulfide
3.
As
an
added
margin
of
safety,
we
accordingly
recommend
the
action
levels
of:

Total
Available
Cyanide:
250
mg
HCN/
Kg
waste
Total
Available
Sulfide:
500
mg
H2S/
Kg
waste
TEST
METHOD
TO
DETERMINE
HYDROGEN
CYANIDE
RELEASED
FROM
WASTES
1.
Scope
and
Application
1.1
This
method
is
applicable
to
all
wastes,
with
the
condition
that
wastes
that
are
combined
with
acids
do
not
form
explosive
mixtures.

1.2
This
method
provides
a
way
to
determine
the
specific
rate
of
release
of
hydrocyanic
acid
upon
contact
with
an
aqueous
acid.

1.3
This
test
measures
only
the
hydrocyanic
acid
evolved
at
the
test
conditions.
It
is
not
intended
to
measure
forms
of
cyanide
other
than
those
that
are
evolvable
under
the
test
conditions.

2.
Summary
of
Method
2.1
An
aliquot
of
acid
is
acidified
to
pH
2
in
a
closed
system.
The
gas
generated
is
swept
into
a
scrubber.
The
analyte
is
quantified.
The
procedure
for
quantifying
the
cyanide
is
Method
9010
starting
with
Step
7.3.5.
of
that
method
(
attached)

3.
Sample
Handling
and
Preservation
3.1
Samples
containing,
or
suspected
of
containing,
sulfide
or
a
combination
of
sulfide
and
cyanide
wastes
should
be
collected
with
a
minimum
of
aeration.
The
sample
bottle
should
be
filled
completely,
excluding
all
head
space,
and
stoppered.
Analysis
should
commence
as
soon
as
possible,
and
samples
should
be
kept
in
a
cool,
dark
place
until
analysis
begins.

3.2
It
is
suggested
that
samples
of
cyanide
wastes
be
tested
as
quickly
as
possible.
Although
they
can
be
preserved
by
adjusting
the
sample
pH
to
12
with
strong
base,
this
will
cause
dilution
of
the
sample,
increase
the
ionic
strength,
and,
possibly,
change
other
physical
or
chemical
characteristics
of
the
waste
which
may
affect
the
rate
of
release
of
the
hydrocyanic
acid.
Storage
of
samples
should
be
under
refrigeration
and
in
the
dark.

3.3
Testing
should
be
performed
in
a
ventilated
hood.

4.
Apparatus
(
see
Figure
1)

4.1
Three­
neck,
round­
bottom
flask
with
24/
40
ground­
glass
joints,
500
ml.

4.2
Stirring
apparatus
to
achieve
approximately
30
rpm.
This
may
be
a
rotating
magnet
and
stirring
bar
combination
or
an
overhead
motor­
driven
propeller
stirrer.

4.3
Separatory
funnel
with
pressure­
equalizing
tube
and
24/
40
ground­
glass
joint
and
Teflon
sleeve.

4.4
Flexible
tubing
for
connection
from
nitrogen
supply
to
apparatus.

4.5
Water­
pumped
or
oil­
pumped
nitrogen
gas
with
two­
stage
regulator.

4.6
Rotometer
for
monitoring
nitrogen
gas
flow
rate.
Figure
1
5.0
Reagents
5.1
Sulfuric
acid
0.005
M
5.2
Cyanide
reference
solution:
Dissolve
approximately
2.5
gm
of
KOH
and
2.51
gm
of
KCN
in
1
liter
of
distilled
water.
Cyanide
concentration
in
this
solution
is
1
mg/
ml.

5.3
NaOH
solution,
1.25N:
dissolve
50
gm
of
NaOH
in
distilled
water
and
dilute
to
1
liter
with
distilled
water.

5.4
NaOH
solution,
0.25N:
Dilute
200
mL
of
sodium
hydroxide
solution
to
1
liter
with
distilled
water.

5.5
Stock
cyanide
solution,
1
mg/
ml:
Dissolve
2.51
gm
KCN
and
2
gm
KOH
in
1
liter
of
distilled
water.
Standardized
with
0.0192
N
AgNO3.
Dilute
to
appropriate
concentration
so
that
1
ml
­
1
mg
CN.

5.6
Intermediate
cyanide
solution:
Dilute
50
ml
of
stock
solution
to
1
liter
with
distilled
water.

5.7
Standard
cyanide
solution,
5
mg/
L:
Prepare
fresh
daily
by
diluting
100.
ml
of
intermediate
solution
to
1
liter
with
distilled
water
and
store
in
a
glass­
stoppered
bottle.

5.8
Silver
nitrate
solution:
Prepare
by
crushing
approximately
5
gm
of
AgNO3
crystals
and
drying
to
constant
weight
at
40
°
C.
Weigh
3.3
gm
dried
AgNO3,
dissolve
in
distilled
water,
and
dilute
to
1
liter.

5.9
Rhodanine
indicator:
Dissolve
20
mg
p­
dimethylaminobenzalrhodanine
in
100
ml
of
acetone.

5.10
Methyl
red
indicator:
Prepare
0.02
gm
dissolved
in
60
ml
distilled
water
and
40
ml
acetic
acid.

6
System
Check
6.1
The
operation
of
the
system
can
be
checked
using
the
cyanide
reference
solution.
The
reference
solution
can
be
used
to
verify
system
operation.

7.0
Procedure
7.1
Add
500
mL
of
0.25N
NaOH
solution
to
a
calibrated
scrubber
and
dilute
with
distilled
water
to
obtain
an
adequate
depth
of
liquid.

7.2
Close
the
system
and
adjust
the
flow
rate
of
nitrogen
using
the
rotometer.
Flow
should
be
60
ml/
min.

7.3
Add
10
gm
of
the
waste
to
be
tested
to
the
system.

7.4
With
the
nitrogen
flowing,
add
enough
acid
to
fill
the
system
1/
2
full.
While
starting
the
30
minute
test
period.

7.5
Begin
stirring
while
the
acid
is
entering
the
round
bottomed
flask.

7.6
After
30
minutes
close
off
the
nitrogen
and
disconnect
the
scrubber.
Determine
the
amount
of
cyanide
in
the
scrubber
by
Method
9010,
starting
with
step
7.3.5.
of
the
method
(
attached).
8.0
Calculations
8.1
Determine
the
specific
rate
of
release
of
HCN
­
Concentration
of
HCN
in
diluted
scrubber
solution
(
mg/
L)
=
A
This
is
obtained
from
Method
9010.

­
Volume
of
solution
in
scrubber
(
l)
=
L
­
Weight
of
waste
used
(
Kg)
=
W
­
Time
of
measurement
=
Time
N2
stopped
­
Time
N2
started
(
seconds)
=
S
R
=
specific
rate
of
release
=
A
°
L
W
°
S
Total
available
HCN
=
R
°
1800
mg/
Kg
METHOD
9010
TOTAL
AND
AMENABLE
CYANIDE
1.0
Scope
and
Application
1.1
Method
9010
is
used
to
determine
the
concentration
of
inorganic
cyanide
in
a
waste
or
leachate.
The
method
detects
inorganic
cyanides
that
are
present
as
either
simple
soluble
salts
or
complex
radicals.
It
is
used
to
determine
values
for
both
total
cyanide
and
cyanide
amenable
to
chlorination.
Method
9010
does
not
determine
the
"
reactive"
cyanide
content
of
wastes
containing
iron­
cyanide
complexes.
(
As
an
alternative
to
Method
9010,
autoanalyzers
may
be
used
for
cyanide
analysis
if
the
analyst
adheres
to
the
precautions
and
quality
control
requirements
specified
in
this
method.)

2.0
Summary
of
Method
2.1
The
waste
is
divided
into
two
parts.
One
is
chlorinated
to
destroy
susceptible
complexes.
Each
part
is
then
distilled
to
remove
interferences
and
analyzed
for
cyanide.
The
fraction
amenable
to
chlorination
is
determined
by
the
difference
in
values.

2.2.
During
the
distillation,
cyanide
is
converted
to
hydrogen
cyanide
vapor,
which
is
trapped
in
a
scrubber
containing
sodium
hydroxide
solution.
This
solution
is
then
titrated
with
standard
silver
nitrate.

3.0
Interferences
3.1
Sulfides
interfere
with
the
titration.
They
may
be
precipitated
with
cadmium
3.2
Fatty
acids
form
soaps
under
alkaline
titration
conditions
and
interfere.
They
may
be
extracted
with
a
suitable
solvent.

3.3
Oxidizing
agents
may
decompose
the
cyanide.
They
may
be
treated
with
ascorbic
acid.

3.4
Thiocyanate
presence
will
interfere
by
distilling
over
in
the
procedure.
This
can
be
prevented
by
adding
magnesium
chloride.

3.5
Aldehydes
and
ketones
may
convert
cyanide
to
cyanohydrin
under
the
acid
distillation
conditions.

4.0
Apparatus
and
Materials
4.1
Microburet,
5.0
ml,
for
titration.

4.1
Flasks,
condenser,
and
tubing
are
needed
as
shown
in
Figure
1.
The
boiling
flash
should
be
of
1­
liter
size
with
inlet
tube
and
provision
for
a
condenser.
The
gas
absorber
may
be
a
Fisher­
Milligan
scrubber.
Assemble
as
shown
in
Figure
1.
Figure
1
5.0
Reagents
5.1
ASTM
Type
II
water
(
ASTM
D1193)
or
better
quality:
Water
should
be
monitored
for
impurities.

5.2
Calcium
hypochlorite
solution:
Dissolve
5
g
of
hypochlorite,
Ca(
OCl2),
in
100
ml
of
Type
II
water.

5.3
Sodium
hydroxide
solution
(
1.25
N):
Dissolve
50
g
of
sodium
hydroxide
(
NaOH)
in
Type
II
water
and
dilute
to
1
liter.

5.4
Ascorbic
acid:
cyrstals.

5.5
Potassium
iodide­
starch
paper.

5.6
Lead
acetate
paper.

5.7
Cadmium
carbonate
(
powdered).

5.8
Hexane.

5.9
Acetic
acid
solution
(
1:
9).

5.10
Conc.
H2SO4
5.11
Silver
nitrate
standard
solution
(
0.0192
N):
Dry
5
g
AgNO3
crystals
to
constant
weight
at
40
°
C.
Weigh
out
3.2647
g
and
dissolve
in
Type
II
water.
Dilute
1000
ml
(
1
ml
=
1
mg
CN).

5.12
Rhodanine
indicator
solution:
Dissolve
20
mg
p­
dimethyl­
aminobenzalrhodanine
in
100
ml
acetone.

5.13
Magnesium
chloride
solution:
Weigh
510
g
of
MgCl2
C
6H2O
into
a
1­
liter
volumetric
flask.
Dissolve
and
bring
to
volume
with
Type
II
water.

6.0
Sample
Collection,
Preservation
and
Handling
6.1
All
samples
must
have
been
collected
using
a
sampling
plan
that
addresses
the
considerations
discussed
in
Section
One
of
this
manual.

6.2
Samples
should
be
collected
in
plastic
or
glass
containers
of
1­
liter
size
or
larger.
All
bottles
must
be
thoroughly
cleaned
and
thoroughly
rinsed
to
remove
soluble
materials
from
containers.

6.3
Oxidizing
agents
such
as
chlorine
decompose
most
cyanides.
To
determine
whether
oxidizing
agents
are
present,
test
a
drop
of
the
sample
with
potassium
iodide­
starch
test
paper;
a
blue
color
indicates
the
need
for
treatment.
Add
ascorbic
acid
a
few
crystals
at
a
time
until
a
drop
of
sample
produces
no
color
on
the
indicator
paper.
Then
add
an
additional
0.6
g
of
ascorbic
acid
for
each
liter
of
water.

6.4
Samples
must
be
preserved
with
2
ml
of
10
N
sodium
hydroxide
per
liter
of
sample
(
pH
is
greater
than
or
equal
to
12)
at
the
time
of
collection.

6.5
Samples
should
be
refrigerated
to
4
°
C
when
possible
and
analyzed
as
soon
as
possible.
7.0
Procedure
7.1
If
interferences
are
known
or
suspected
to
be
present,
test
and
treat
the
sample
as
follows.

7.1.1
Sulfides:
If
a
drop
of
the
distillate
on
lead
acetate
test
paper
indicates
the
presence
of
sulfides,
treat
25
ml
more
of
the
sample,
than
the
amount
required
for
the
cyanide
determination
with
powdered
cadmium
carbonate.
Yellow
cadmium
sulfide
precipitates
of
the
sample
contains
sulfide.
Repeat
this
operation
until
a
drop
of
the
treated
sample
solution
does
not
darken
the
lead
acetate
test
paper.
Filter
the
solution
through
a
dry
filter
paper
into
a
dry
beaker,
and
from
the
filtrate,
measure
the
sample
to
use
for
analysis.
Avoid
a
large
excess
of
cadmium
and
a
long
contact
time
in
order
to
minimize
a
loss
by
complexation
or
occlusion
of
cyanide
on
the
precipitated
material.
Sulfides
should
be
removed
prior
to
preservation
with
sodium
hydroxide.

7.1.2
Fatty
acids:
Acidify
the
sample
with
acetic
acid
(
1:
9)
to
pH
6.0
to
7.0.
CAUTION:
Toxic
hydrogen
cyanide
can
be
generated
in
an
acid
solution.
This
operation
must
be
performed
in
the
hood
and
the
sample
left
there
until
it
can
be
made
alkaline
again
after
the
extraction
has
been
performed.
Then
extract
with
isooctane,
hexane,
or
chloroform
(
preference
in
order
listed)
with
a
solvent
volume
equal
to
20%
of
the
sample
volume.
One
extraction
is
usually
adequate
to
reduce
the
fatty
acids
below
the
interference
level.
Avoid
multiple
extractions
or
a
long
contact
time
at
low
pH
in
order
to
keep
the
loss
of
HCN
at
a
minimum.
When
the
extraction
is
completed,
immediately
raise
the
pH
of
the
sample
to
above
12
with
NaOH
solution.

7.1.3
Oxidizing
agents:
Test
a
drop
of
the
sample
with
potassium
iodide­
starch
test
paper
(
KI­
starch
paper).
A
blue
color
indicates
the
need
for
treatment.
Add
ascorbic
acid
a
few
crystals
at
a
time
until
a
drop
of
sample
produces
no
color
on
the
indicator
paper.
Then
add
an
additional
0.6
g
of
ascorbic
acid
for
each
liter
of
sample
volume.

7.2
Chlorination
of
a
sample
aliquot
7.2.1
Take
a
500­
mL
sample
aliquot
or
a
sample
volume
diluted
to
500
ml.
Add
calcium
hypochlorite
solution
dropwise
while
agitating
and
maintaining
the
pH
between
11
and
12
with
sodium
hydroxide
solution
(
1.25
N).
CAUTION:
The
initial
reaction
product
of
alkaline
chlorination
is
the
very
toxic
gas
cyanogen
chloride;
therefore,
it
is
necessary
that
this
reaction
be
performed
in
a
hood.
For
convenience,
the
sample
may
be
agitated
in
a
1­
liter
beaker
by
a
magnetic
stirring
device.

7.2.2
Test
for
residual
chlorine
with
KI­
starch
paper
and
maintain
this
excess
for
1
hr,
continuing
agitation.
A
distinct
blue
color
on
the
test
paper
indicates
a
sufficient
chlorine
level.
If
necessary,
add
additional
hypochlorite
solution.

7.2.3
After
1
hr,
add
0.5­
g
portions
of
ascorbic
acid
until
KI­
starch
paper
shows
no
residual
chlorine.
Add
an
additional
0.5
g
of
ascorbic
acid
to
ensure
the
presence
of
excess
reducing
agent.

7.3
Take
the
aliquot
treated
in
Section
7.2
plus
either
a
second
500­
ml
aliquot
of
the
untreated
sample
or
an
untreated
aliquot
diluted
to
500
ml
in
the
1­
liter
boiling
flask
and
separately
distill
as
follows.

7.3.1
Add
50
mL
of
sodium
hydroxide
(
1.25
N)
to
the
absorbing
tube
and
dilute
if
necessary
with
Type
II
water
to
obtain
an
adequate
depth
of
liquid
in
the
absorber.
Connect
the
boiling
flask,
condenser,
absorber,
and
trap
in
the
train.

7.3.2
Start
a
slow
stream
of
air
entering
the
boiling
flask
by
adjusting
the
vacuum
source.
Adjust
the
vacuum
so
that
approximately
one
bubble
of
air
per
second
enters
the
boiling
flask
through
the
air
inlet
tube.
CAUTION:
The
bubble
rate
will
not
remain
constant
after
the
reagents
have
been
added
and
while
heat
is
being
applied
to
the
flask.
The
air
rate
must
therefore
occasionally
be
adjusted
to
prevent
the
solution
in
the
foiling
flask
from
backing
up
into
the
air
inlet
tube.

7.3.3
Slowly
add
25
ml
conc.
sulfuric
acid
through
the
air
inlet
tube.
Rinse
the
tube
with
Type
II
water
and
allow
the
air
flow
to
mix
the
flask
contents
for
3
min.
Pour
20
ml
of
magnesium
chloride
solution
into
the
air
inlet
and
wash
down
with
a
stream
of
water.

7.3.4
Heat
the
solution
to
boiling,
taking
care
to
prevent
the
solution
from
backing
up
into
and
overflowing
from
the
air
inlet
tube.
Reflux
for
1
hr.
Turn
off
the
heat
and
continue
the
airflow
for
at
least
15
minutes.
After
cooling
the
boiling
flask,
disconnect
the
absorber
and
close
off
the
vacuum
source.

7.3.5
Drain
the
solution
from
the
absorber
into
a
250­
mL
volumetric
flask
and
bring
to
volume
with
Type
II
water
washings
from
the
absorber
tube.

7.4
Titration
7.4.1
Add
the
solution
or
an
aliquot
diluted
to
250
ml
to
a
500­
ml
erlenmeyer
flask.
Add
10­
12
drops
rhodanine
indicator.

7.4.2
Titrate
with
standard
silver
nitrate
to
the
first
change
in
color
from
yellow
to
brownish­
pink.
Titrate
a
Type
II
water
blank
using
the
same
amount
of
sodium
hydroxide
and
indicator
as
in
the
sample.

7.4.3
The
analyst
should
familiarize
himself
with
the
end
point
of
the
titration
and
the
amount
of
indicator
to
be
used
before
actually
titrating
the
samples.
A
5­
or
10­
ml
microburet
may
be
conveniently
used
to
obtain
precise
titration.

7.5
Titrate
a
blank
using
Type
II
water
in
an
identical
manner.

7.6
Calculation:

1.
CN,
mg/
L
=
{[(
A
­
B)
1,000]
÷
(
ml
orig.
sample)}
X
[
250
÷
ml
of
aliquot
titrated]

where:

A
=
volume
of
AgNO3
for
titration
of
sample.
B
=
volume
of
AgNO3
for
titration
of
blank.

2.
Cyanide
amenable
to
chlorination:

CN,
mg/
l
=
C
­
D
where:

C
=
mg/
l
total
cyanide
in
unchlorinated
aliquot
D
=
mg/
l
total
cyanide
in
chlorinated
aliquot
7.7
Duplicates,
spiked
standards,
and
check
standards
should
be
routinely
analyzed.

8.0
QUALITY
CONTROL
8.1
All
quality
control
data
should
be
maintained
and
available
for
easy
reference
or
inspection.

8.2
Employ
a
minimum
of
one
blank
per
sample
batch
to
determine
if
contamination
or
any
memory
effects
are
occurring.

8.3
Analyze
check
standards
after
approximately
every
15
samples.

8.4
Run
one
duplicate
for
every
10
samples.
A
duplicate
sample
is
a
sample
brought
through
the
whole
sample
preparation
process.

8.5
Spiked
samples
or
standard
reference
materials
shall
be
periodically
employed
to
ensure
that
correct
procedures
are
being
followed
and
that
all
equipment
is
operating
properly.

8.6
The
method
of
standard
additions
shall
be
used
for
the
analysis
of
all
samples
that
suffer
from
matrix
interferences.
TEST
METHOD
TO
DETERMINE
HYDROGEN
SULFIDE
RELEASED
FROM
WASTES
1.
SCOPE
AND
APPLICATION
1.1
This
method
is
applicable
to
all
wastes,
with
the
condition
that
waste
which
are
combined
with
acids
do
not
form
explosive
mixtures.

1.2
This
method
provides
a
way
to
determine
the
specific
rate
of
release
of
hydrogen
sulfide
upon
contact
with
an
aqueous
acid.

1.3
This
procedure
releases
only
the
evolved
hydrogen
sulfide
evolved
at
the
test
conditions.
It
is
not
intended
to
measure
forms
of
sulfide
other
than
those
that
are
evolvable
under
the
test
conditions.

2.
SUMMARY
OF
METHOD
2.1
An
aliquot
of
acid
is
acidified
to
pH
2
in
a
closed
system.
The
gas
generated
is
swept
into
a
scrubber.
The
analyte
is
quantified.
The
procedure
for
quantifying
the
sulfide
is
given
in
Method
376.1.

3.
SAMPLE
HANDLING
AND
PRESERVATION
3.1
Samples
containing,
or
suspected
of
containing,
sulfide
wastes
should
be
collected
with
a
minimum
of
aeration.
The
sample
bottle
should
be
filled
completely,
excluding
all
head
space,
and
stoppered.
Analysis
should
commence
as
soon
as
possible,
and
samples
should
be
kept
in
a
cool,
dark
place
until
analysis
begins.

6.2
It
is
suggested
that
samples
of
sulfide
wastes
be
tested
as
quickly
as
possible.
Although
they
can
be
preserved
by
adjusting
the
sample
pH
to
12
with
strong
base
and
addition
of
zinc
acetate
to
the
sample,
this
will
cause
dilution
of
the
sample,
increase
the
ionic
strength
and,
possibly,
change
other
physical
or
chemical
characteristics
of
the
waste
which
may
affect
the
rate
of
release
of
the
hydrogen
sulfide.
Storage
of
samples
should
be
under
refrigeration
and
in
the
dark.

6.3
Testing
should
be
performed
in
a
ventilated
hood.

4.
APPARATUS
(
See
Figure
1)

4.1
Three­
neck,
round­
bottom
flask,
with
24/
40
ground­
glass
joints,
500­
ml.

4.2
Stirring
apparatus
to
achieve
approximate
30
rpm.
This
may
be
a
rotating
magnet
and
stirring
bar
combination
or
an
overhead
motor­
driven
propellor
stirrer.

4.3
Separatory
funnel
with
pressure
equalizing
tube
and
24/
40
ground
glass
joint
and
teflon
sleeve.

4.4
Flexible
tubing
for
connection
from
nitrogen
supply
to
apparatus.

4.5
Water
pumped
or
oil
pumped
nitrogen
gas
with
two
stage
regulator.

4.6
Rotometer
for
monitoring
nitrogen
gas
flow
rate.

4.7
Industrial
hygiene
type
detector
tube
for
sulfide
(
100­
2000
ppm
range).
Figure
1
5.
REAGENTS
5.1
Sulfuric
acid,
0.005
M
5.2
Sulfide
reference
solution:
Dissolve
4.02
g
of
Na2S
°
9H2O
in
1.0
liters
distilled
water.
This
is
680
ppm
hydrogen
sulfide.
Dilute
this
stock
solution
to
cover
the
analytical
range
required
(
100
ppm
to
680
ppm).

5.5
NaOH
solution,
1.25N:
dissolve
50
gm
of
NaOH
in
distilled
water
and
dilute
to
1
liter
with
distilled
water.

5.6
NaOH
solution,
0.25N:
Dilute
200
ml
of
sodium
hydroxide
solution
to
1
liter
with
distilled
water.

6.
SYSTEM
CHECK
6.1
The
operation
of
the
system
can
be
checked
using
the
sulfide
reference
solution.
The
reference
solution
can
be
used
to
verify
system
operation.

7.
PROCEDURE
The
procedure
is
dependent
on
the
method
chosen
for
quantification.

­
If
an
absorbent
tube
indicator
is
used
for
quantification,
the
analyst
should
start
the
procedure
with
Step
7.2.0
­
If
another
procedure
is
chosen,
the
analyst
should
start
the
procedure
with
7.1.0
7.1.0
Procedure
employing
scrubber
solution
with
wet
method
quantification
7.1.1
Add
500
mL
of
0.25N
NaOH
solution
to
a
calibrated
scrubber
and
dilute
with
distilled
water
to
obtain
an
adequate
depth
of
liquid.

7.1.2
Assemble
the
system
and
adjust
the
flow
rate
of
nitrogen
using
the
rotometer.
Flow
should
be
60
mL/
min.

7.1.3
Add
10
gm
of
the
waste
to
be
tested
to
the
system.

7.1.4
With
the
nitrogen
flowing,
add
enough
acid
to
fill
the
flask
1/
2
full,
while
starting
the
30
minute
test
period.

7.1.5
Begin
stirring
while
the
acid
is
entering
the
round
bottomed
flask.

7.1.6
After
30
minutes
close
off
the
nitrogen
and
disconnect
the
scrubber.
Determine
the
amount
of
sulfide
in
the
scrubber
by
Method
376.1
(
enclosed).
following
methods
7.1.7
Go
to
Section
8.1
for
calculation
of
specific
rate
of
release.

7.2.0
Procedure
employing
dry
absorbent
indicator
tube
for
quantification.

7.2.1
Assemble
the
system
with
the
absorber
tube
in
place,
making
sure
that
the
tube
has
the
proper
orientation
(
see
manufacturer's
literature).
7.2.2
Adjust
the
flow
rate
of
nitrogen
to
be
60
ml/
min
using
the
rotometer.

7.2.3
Add
10
gm
of
waste
to
the
system.

7.2.4
Start
the
test
by
adding
enough
acid
of
pH
2
to
fill
the
round
bottom
flask
half
full.

7.2.5
After
30
minutes,
read
the
length
of
the
stain
on
the
indicator
tube.
Follow
the
manufacturer's
directions
in
determining
the
concentration
of
sulfide
in
the
gas
using
the
length
of
the
stain
and
the
amount
of
gas
passed
through
the
tube.

7.2.6
Go
to
Section
8.2
to
calculate
the
specific
rate
of
release.

8.
CALCULATIONS
8.1
Determine
the
specific
rate
of
release
of
H2S
Concentration
of
H2S
in
scrubber
(
mg/
L).
This
is
obtained
from
method
376.1
or
376.2.
=
A
Volume
of
solution
in
scrubber
(
l)
=
L
Weight
of
waste
used
(
kg)
=
W
Time
of
experiment
=
Time
N2
stopped
­
Time
N2
started
(
seconds)
=
S
R
=
spec.
rate
of
release
=
(
A
°
L)
÷
(
W
°
S)

Total
available
H2S
(
mg/
kg)
=
R
x
1800
mg/
kg
8.2
Calculation
for
absorber
tube
determination
of
sulfide
Final
detector
tube
reading
(
ul)
=
L
Flow
rate
N2
through
tube
(
ml/
min)
=
V
Time
of
flow
(
min)
=
T
Conversion
factor
=
1.1
<
Note:
this
is
meant
to
be
1.42
based
on
below>
=
D
Weight
of
sample
(
kg)
=
W
Specific
rate
of
release
=
R
R
=
[
L
÷
(
1000
°
W)]
°
(
1.42)
=
mg/
kg
of
H2S
SULFIDE
Method
376.1
(
Titrimetric,
Iodine)

STORET
NO.
Total
00745
Dissolved
00746
1.
Scope
and
application
1.1
This
method
is
applicable
to
the
measurement
of
total
and
dissolved
sulfides
in
drinking,
surface,
and
saline
waters,
domestic
and
industrial
wastes.
1.2
Acid
insoluble
sulfides
are
not
measured
by
the
use
of
this
test.
(
Copper
sulfide
is
the
only
common
sulfide
in
this
class).
1.3
This
method
is
suitable
for
the
measurement
of
sulfide
in
concentration
above
1
mg/
l.

2.
Summary
of
method
2.1
Excess
iodine
is
added
to
a
sample
which
may
or
may
not
have
been
treated
with
zinc
acetate
to
produce
zinc
sulfide.
The
iodine
oxidizes
the
sulfide
to
sulfur
under
acidic
conditions.
The
excess
iodine
is
backtitrated
with
sodium
thiosulfate
or
phenylarsine
oxide.
3.
Comments
3.1
Reduced
sulfur
compounds,
such
as
sulfite,
thiosulfate
and
hydrosulfite,
which
decompose
in
acid
may
yield
erratic
results.
Also,
volatile
iodine­
consuming
substances
will
give
high
results.
3.2
Samples
must
be
taken
with
a
minimum
of
aeration.
Sulfide
may
be
volatilized
by
aeration
and
any
oxygen
inadvertently
added
to
the
sample
may
convert
the
sulfide
to
an
unmeasurable
form.
3.3
If
the
sample
is
not
preserved
with
zinc
acetate
and
NaOH,
the
analysis
must
be
started
immediately.
Similarly,
the
measurement
of
dissolved
sulfides
must
also
be
commenced
immediately.
4.
Apparatus:
Ordinary
laboratory
glassware.
5.
Reagents
5.1
Hydrochloric
acid,
HCl,
6
N
5.2
Standard
iodine
solution,
0.0250
N:
Dissolve
20
to
25
g
KI
in
a
little
water
in
a
liter
volumetric
and
add
3.2
g
iodine.
Allow
to
dissolve.
Dilute
to
1
liter
and
standardize
against
0.0250
N
sodium
thiosulfate
or
phenylarsine
oxide
using
a
starch
indicator.
5.3
Phenylarsine
oxide
0.0250
N:
commercially
available.
5.4
Starch
indicator:
commercially
available.
5.5
Procedure
for
standardization
(
see
Residual
Chlorine­
iodometric
titration
Method
330.3,
section
5.15).

Approved
for
NPDES
Issued
1971
Editorial
revision
1978
6.
Procedure
6.1
Unprecipitated
sample
6.1.1
Place
a
known
amount
of
standard
iodine
solution
(
5.2)
into
a
500
ml
flask.
The
amount
should
be
estimated
to
be
in
excess
of
the
amount
of
sulfide
expected.
6.1.2
Add
distilled
water,
if
necessary,
to
bring
the
volume
to
approximately
20
ml.
6.1.3
Add
2
ml
of
6
N
HCl
(
5.1).
6.1.4
Pipet
200
ml
of
sample
into
the
flask,
keeping
the
tip
of
the
pipet
below
the
surface
of
the
sample.
6.1.5
If
the
iodine
color
disappears,
add
more
iodine
until
the
color
remains.
Record
the
total
number
of
milliliters
of
standard
iodine
used
in
performing
steps
6.1.1
and
6.1.5.
6.1.6.
Titrate
with
the
reducing
solution
(
0.0250
N
sodium
thiosulfate
or
0.0250
N
phenylarsine
oxide
solution
(
5.3))
using
a
starch
indicator
(
5.4)
until
the
blue
color
disappears.
Record
the
number
of
milliliters
used.
6.2
Precipitated
samples
6.2.1
Add
the
reagents
to
the
sample
in
the
original
bottle.
Perform
steps
6.1.1,
6.1.3,
6.1.5,
and
6.1.6.
6.3
Dewatered
samples
6.3.1
Return
the
glass
fibre
filter
paper
which
contains
the
sample
to
the
original
bottle.
Add
200
ml
distilled
water.
Perform
steps
6.1.1,
6.1.3,
6.1.5,
and
6.1.6.
6.3.2
The
calculations
(
7)
should
be
based
on
the
volume
of
original
sample
put
through
the
filter.
7.
Calculations
7.1
One
ml
of
0.0250
N
standard
iodine
solution
(
5.2)
reacts
with
0.4
mg
of
sulfide
present
in
the
titration
vessel.
7.2
Use
the
formula
mg/
l
sulfide
=
[
400
(
A
­
B)]
÷
ml
sample
where:

A
=
ml
of
0.0250
N
standard
iodine
solution
(
5.2)
B
=
ml
of
0.0250N
standard
reducing
sodium
thosulfate
or
phenylarsine
oxide)
solution
(
5.3).

8.
Precision
and
accuracy
8.1
Precision
and
accuracy
for
this
method
have
not
been
determined.

Bibliography
1.
Standard
Methods
for
the
Examination
of
Water
and
Wastewater,
14th
Edition,
p
505,
Method
428D,
(
1975).
