Document ID: EPA-HQ-OW-2004-0001-0066
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2005-05-13T04:00Z

TSC­
02­
0442
1
METHOD
314.1
DETERMINATION
OF
PERCHLORATE
IN
DRINKING
WATER
USING
INLINE
SAMPLE
PRE­
CONCENTRATION/
MATRIX
ELIMINATION
ION
CHROMATOGRAPHY
WITH
SUPPRESSED
CONDUCTIVITY
DETECTION
RESEARCH
SUMMARY
April
2005
Herbert
P.
Wagner
(
Lakeshore
Engineering
Services,
Inc.)
Barry
V.
Pepich
(
Shaw
Environmental,
Inc.)
Chris
Pohl,
Douglas
Later,
Robert
Joyce,
Kannan
Srinivasan,
Brian
DeBorba,
Dave
Thomas,
and
Andy
Woodruff
(
Dionex,
Inc.
Sunnyvale,
Ca)
David
J.
Munch
(
U.
S.
EPA,
Office
of
Ground
Water
and
Drinking
Water)

TECHNICAL
SUPPORT
CENTER
OFFICE
OF
GROUND
WATER
AND
DRINKING
WATER
U.
S.
ENVIRONMENTAL
PROTECTION
AGENCY
CINCINNATI,
OHIO
45268
TSC­
02­
0442
2
TABLE
OF
CONTENTS
TITLE
PAGE  .  ...                          .  
1
TABLE
OF
CONTENTS                         ..   .
2
LIST
OF
ACRONYMS
................................................................................................................
3
1.
INTRODUCTION.............................................................................................................
3
2.
INCREASING
METHOD
SENSITIVITY.........................................................................
5
2.1
COMPARISON
OF
2­
mm
VERSUS
4­
mm
COLUMNS...................................................
5
2.2
SAMPLE
PRE­
CONCENTRATION/
MATRIX
ELIMINATION......................................
5
2.3
OPTIMIZING
THE
CRYPTAND
CONCENTRATOR
COLUMN
PROTOCOLS
............
6
2.3.1
Direction
of
Load
and
Rinse
Solutions
..............................................................................
6
2.3.2
Comparison
of
Perchlorate
Peak
Shape
at
Room
Temperature
and
35

C...........................
8
2.3.3
Use
of
Sodium
Ion
to
Improve
Trapping
Efficiency...........................................................
8
2.3.4
Concentration
and
Volume
of
Rinse
Solution.
...................................................................
9
2.3.5
Concentration
and
Volume
of
Wash
Solution
....................................................................
10
2.3.6
Optimization
in
the
Synthetic
Sample
Matrix
....................................................................
11
2.3.7
Concentrator
Column
Trapping
Capacity...........................................................................
13
3.
PRELIMINARY
EVALUATION
OF
314.1
PROTOCOLS...............................................
13
4.
EVALUATION
OF
SURROGATES
FOR
AS16
COLUMNS...........................................
15
4.1
MELLITIC
ACID
(
MA)....................................................................................................
16
4.2
BENZENESULFONIC
ACID
(
BSA)
................................................................................
16
4.3
4­
CHLOROBENZENESULFONIC
ACID
(
4­
Cl
BSA)
.....................................................
16
4.4
TRIFLUROBENZOIC
ACIDS
(
TFBA)
............................................................................
16
4.5
5­
SULFOSALICYLIC
ACID
(
SSA)
.................................................................................
16
4.6
DINITROBENZOIC
ACID
(
DNBA)
................................................................................
16
5.
EVALUATION
OF
THE
CRYPTAND
ANALYTICAL
COLUMN
.................................
18
5.1.
SEPARATION
OF
4­
Cl
BSA
ON
THE
CRYPTAND
ANALYTICAL
COLUMN............
18
5.2.
USE
OF
LITHIUM
AND
SODIUM
HYDROXIDE
ELUENTS........................................
18
5.2.1.
Need
for
ATC
trap
Column
to
Remove
Carbonate.............................................................
19
6.
IMPROVING
METHOD
ROBUSTNESS
 
PHASE
1
......................................................
19
6.1
DETERMINATION
OF
LCMRL......................................................................................
19
6.2
STERILE
FILTRATION...................................................................................................
19
6.2.1
Background
Confirmation
from
Sterile
Filtration
Devices
.................................................
19
6.3
INCREASING
ELUENT
CONCENTRATION
FROM
50­
mM
TO
65­
mM
NaOH...........
20
6.4
CARRYOVER
IN
GROUNDWATER
COMPARED
TO
SURFACE
WATER.................
21
6.5
ADDITION
OF
A
100­
mM
NaOH
COLUMN
CLEANING
STEP....................................
22
7.
DEVELOPMENT
OF
DUAL
ELUENT
GENERATION..................................................
23
8.
INITIAL
ASSESSMENT
OF
P&
A
DATA
WITH
THE
AS16
COLUMN.........................
24
8.1
METHOD
PROTOCOLS
FOR
AS16
COLUMN..............................................................
24
8.2
LCMRL
AND
P&
A
RESULTS.........................................................................................
24
8.3
COMPARATIVE
STUDY
USING
EPA
METHOD
314.1
AND
331.0
.............................
25
9.
DEVELOPMENT
AND
EVALUATION
OF
AS20
CONFIRMATION
COLUMN
..........
26
9.1
LCMRL
AND
P&
A
RESULTS.........................................................................................
27
10.
IMPROVING
METHOD
ROBUSTNESS
 
PHASE
2
......................................................
27
10.1
EVALUATION
OF
RINSE
TIME
AND
LSSM
CONCENTRATION
..............................
27
10.2
EVALUATION
OF
DRINKING
WATER
MATRICES
USING
100
mg/
L
LSSM............
28
TSC­
02­
0442
3
11.
FINAL
CONCENTRATOR
COLUMN
EVALUATION...................................................
29
11.1
FINAL
CONCENTRATOR
COLUMN
TRAPPING
EFFICIENCY..................................
29
12.
FINAL
METHOD
PROTOCOLS
FOR
EPA
METHOD
314.1................................................
30
13.
EPA
METHOD
314.1
EXPERIMENTAL
DATA...................................................................
30
13.1
PRIMARY
AS16
COLUMN.................................................................................................
30
13.2
CONFIRMATION
AS20
COLUMN.....................................................................................
31
14.
REFERENCES
.......................................................................................................................
32
LIST
OF
ACRONYMS
4­
Cl
BSA
4­
chlorobenzenesulfonic
acid
BSA
Benzene
Sulfonic
Acid
CCC
Continuing
Calibration
Check
standards
CRATC
Continuously
Regenerated
Anion
Trap
Column
DL
Detection
Limit
DNBA
Dinitrobenzoic
Acid
DQOs
Data
Quality
Objectives
EPA
Environmental
Protection
Agency
IC
Ion
Chromatography
IC­
MS
Ion
Chromatography
Mass
Spectrometry
LCMRL
Lowest
Concentration
Minimum
Reporting
Level
LC­
MS­
MS
Liquid
Chromatography
Mass
Spectrometry
Mass
Spectrometry
LFSSM
Laboratory
Fortified
Synthetic
Sample
Matrix
LSSM
Laboratory
Synthetic
Sample
Matrix
MA
Mellitic
Acid
MRL
Minimum
Reporting
Level
P&
A
Precision
and
Accuracy
QC
Quality
Control
RT
Retention
Time
SSA
5­
sulfosalicylic
Acid
TFBA
Triflurobutyric
Acid
UCMR
Unregulated
Contaminant
Monitoring
Rule
1.
INTRODUCTION
EPA
Method
314.0,
which
has
been
used
under
Unregulated
Contaminant
Monitoring
Regulation
(
UCMR),
supports
a
Minimum
Reporting
Level
(
MRL)
of
4.0
µ
g/
L.
Currently
it
is
the
only
EPA
Method
available
for
monitoring
perchlorate
in
drinking
water.
New
methods
were
sought
that
had
improved
selectivity
and
sensitivity
for
perchlorate,
particularly
in
high
ionic
matrices.
TSC­
02­
0442
4
Up
to
this
point
in
time,
4­
Cl
benzensulfonic
acid
(
4­
Cl
BSA),
which
has
been
detected
in
groundwater
in
the
southwest
United
States,
is
the
only
component
that
has
been
identified
by
IC­
MS
to
coelute
with
perchlorate
on
the
AS16
analytical
column
under
EPA
Method
314.0
conditions.
The
Cryptand
column
technology
developed
by
Dionex
offered
new
possibilities
for
addressing
this
analytical
problem.
Normal
IC
methods
involve
ion
exchange
as
the
mode
of
separation
with
fixed
capacity
separators.
The
Cryptand
columns,
on
the
other
hand,
use
manipulation
of
column
capacity
as
part
of
the
mechanism
for
separation.
The
cation
counter
ion
in
the
eluent
has
a
strong
influence
on
both
the
column
capacity
and
the
kinetics
of
capacity
modification.
These
columns
have
shown
the
ability
to
resolve
perchlorate
and
4­
Cl
BSA.
1
The
use
of
confirmation
columns
to
minimize
the
reporting
of
false
positives
is
commonly
used
with
gas
chromatographic
methods
that
use
detectors
other
than
mass
spectrometry.
The
idea
behind
this
technique
is
to
provide
a
column
with
different
selectivity,
thereby
minimizing
the
possibility
that
any
interference
could
coelute
with
the
analyte
of
interest
on
both
columns.
The
preliminary
objectives
of
this
work
were
to
develop
an
automated,
suppressed
conductivity
method
with
the
lowest
possible
MRL
(
goal
of
0.50
µ
g/
L)
while
incorporating
a
confirmation
column
to
minimize
the
potential
for
false
positives.
This
work
spanned
almost
2.5
years
and
although
the
objectives
did
not
change
during
this
time,
the
means
to
achieve
the
objectives
were
altered
a
couple
of
times
during
the
development
of
this
method.

Preliminary
investigations
directed
at
increasing
method
sensitivity
involved
using
2­
mm
rather
than
4­
mm
columns.
An
approximate
4­
fold
increase
in
sensitivity
can
be
realized
in
very
clean
matrices
by
injecting
the
same
volume
onto
the
2­
mm
columns
compared
to
the
4­
mm
columns.
However,
most
drinking
water
matrices
contain
a
sufficient
quantity
of
other
anions
that
would
prevent
this
direct
injection
technique
from
being
applicable
to
normal
drinking
water
matrices.
Consequently,
the
first
stage
of
research
involved
investigation
of
solid
phase
sample
pretreatment
clean­
up
cartridges
to
remove
chloride,
carbonate/
bicarbonate,
residual
silver
(
from
the
Ag+
cartridge
used
to
remove
chloride)
and
sulfate
prior
to
direct
injection
of
a
large
volume
of
pre­
treated
sample
(
1.3
mL)
onto
the
2­
mm
AS16
columns.
This
technique
was
successful
in
providing
a
method
with
a
MRL
for
perchlorate
of
approximately
0.50
µ
g/
L
in
both
normal
drinking
water
matrices
and
the
1000
mg/
L
Laboratory
Fortified
Synthetic
Sample
Matrices
(
LFSSM).
The
Cryptand
columns
also
provided
a
similar
MRL
for
the
confirmation
column.
The
two
disadvantages
of
these
methods
were
that
they
involved
very
extensive
sample
pretreatment
time
(
approximately
1
hour/
sample)
and
the
use
of
4
different
pretreatment
cartridges,
which
dramatically
increased
the
cost
of
analysis
for
each
sample.

Inline
sample
pre­
concentration
combined
with
matrix
elimination
was
investigated
as
a
means
to
overcome
these
disadvantages.
In
this
work,
a
Dionex
AS40

autosampler
is
used
to
perform
the
sample
pre­
concentration/
matrix
elimination
steps
on­
line.
The
concentrator
column
is
placed
in
the
sample
loop
position.
The
AS40
must
be
used
in
the
proportion
concentration
mode
with
the
bleed
on
and
the
eluent
flow
MUST
be
in
the
same
direction
for
both
the
concentration
and
matrix
elimination
steps.
The
timing
of
the
autosampler
is
programmed
into
the
method
to
allow
for
two
sample
vials
to
be
injected
for
each
sample.
The
first
sample
vial
contains
the
sample
and
the
second
vial
contains
the
rinse
solution
(
1.0
mL
of
10
mM
NaOH),
with
the
filter
cap
raised
to
signify
a
rinse
vial.
TSC­
02­
0442
5
A
significant
amount
of
data
was
generated
with
the
Cryptand
concentrator
and
analytical
columns.
This
data
was
instrumental
in
focusing
the
direction
of
the
development
work.
However,
in
the
end,
the
Cryptand
analytical
column
was
not
incorporated
into
the
final
method.
In
order
to
simplify
the
method,
the
AS20
analytical
column
in
combination
with
the
Cryptand
concentrator,
is
being
used
as
the
confirmation
column.

EPA
Method
314.1
incorporates
the
use
of
2x250­
mm
separator
columns
with
an
automated
sample
pre­
concentration/
matrix
elimination
technique
using
a
4x35­
mm
Cryptand
concentrator
column
to
remove
interfering
anions
and
to
increase
sensitivity.
The
Cryptand
concentrator
column
is
combined
with
a
primary
AS16
analytical
column
and
a
confirmation
AS20
analytical
column
to
minimize
the
potential
for
reporting
false
positives.
All
positive
results
for
perchlorate
above
the
MRL
on
the
primary
column
must
be
confirmed
with
the
confirmation
column.
EPA
Method
314.1
has
a
perchlorate
MRL
of
0.50
µ
g/
L
in
both
drinking
water
and
high
ionic
Laboratory
Synthetic
Sample
Matrices
(
LSSM)
containing
up
to
1000
mg/
L
each
of
chloride,
bicarbonate
and
sulfate.

2.
INCREASING
METHOD
SENSITIVITY
At
the
start
of
this
work,
two
alternatives
were
considered
for
increasing
the
method
sensitivity
using
EPA
Method
314.0
protocols:
the
use
of
a
2­
mm
column,
and
sample
pre­
concentration
combined
with
a
matrix
elimination
step.

2.1
COMPARISON
OF
2­
mm
VERSUS
4­
mm
COLUMNS
An
approximate
4­
fold
increase
in
sensitivity
can,
in
very
clean
matrices,
be
realized
simply
by
injecting
the
same
volume
onto
the
2­
mm
columns
compared
to
the
4­
mm
columns.
However,
most
drinking
water
matrices
contain
a
sufficient
quantity
of
other
anions
that
would
prevent
this
direct
injection
technique
from
being
applicable
to
normal
drinking
water
matrices.
Consequently,
the
first
stage
of
research
involved
investigation
of
solid
phase
sample
pretreatment
clean­
up
cartridges
to
remove
chloride,
carbonate/
bicarbonate
and
sulfate
prior
to
direct
injection
of
a
large
volume
of
pre­
treated
sample
(
1.3
mL)
onto
the
2­
mm
AS16
columns.
This
technique
was
successful
in
providing
a
method
with
a
MRL
for
perchlorate
of
approximately
0.50
µ
g/
L
in
both
normal
drinking
water
matrices
and
in
the
1000
mg/
L
LFSSM.
The
Cryptand
columns
also
provided
a
similar
MRL
for
the
confirmation
column.
The
major
disadvantages
of
this
method
were
that
it
involved
very
extensive
sample
pretreatment
time
(
approximately
1
hour/
sample)
and
the
use
of
4
different
pretreatment
cartridges
that
dramatically
increased
the
cost
of
analysis
for
each
sample.
It
was
envisaged
that
this
method
could
only
be
utilized
as
a
last
resort.
Consequently,
column
concentration/
matrix
elimination
was
investigated
as
a
way
to
eliminate
the
sample
pretreatment
labor
and
materials
costs.

2.2
SAMPLE
PRE­
CONCENTRATION/
MATRIX
ELIMINATION
Preliminary
investigations
using
the
AS40
autosampler
in
the
concentration
mode
and
an
AG11HC
or
AG16
guard
column
in
the
sample
loop
position
showed
that
the
column
concentration
technique
worked
well
in
reagent
water
(
RW)
matrices
but
not
with
the
LFSSM
matrices,
which
are
an
integral
part
of
EPA
Method
314.0.
The
high
ionic
strength
of
the
LFSSM
created
problems
with
the
trapping
and
chromatography
for
TSC­
02­
0442
6
perchlorate.
As
a
result,
it
became
evident
that
a
matrix
elimination
step
(
background
reduction)
would
be
required
if
the
technique
was
to
be
successful.
Again,
incorporating
a
matrix
elimination
step
with
both
the
AG11HC
and
AS16
was
unsuccessful
due
to
band
broadening
or
failure
of
the
perchlorate
to
be
eluted
from
the
trap
column.

The
Cryptand
column
technology
developed
by
Dionex
offered
new
possibilities
for
addressing
this
analytical
problem.
Normal
IC
methods
involve
ion
exchange
as
the
mode
of
separation
with
fixed
capacity
separators.
The
Cryptand
columns,
on
the
other
hand,
use
manipulation
of
column
capacity
as
part
of
the
mechanism
for
separation.
The
cation
counter
ion
in
the
eluent
has
a
strong
influence
on
both
the
concentrator
column
capacity
and
the
capacity
modification
kinetics.

2.3
OPTIMIZING
THE
CRYPTAND
CONCENTRATOR
COLUMN
PROTOCOLS
Once
the
Cryptand
concentrator
column
was
available,
several
parameters
were
investigated
in
order
to
obtain
optimal
trapping
efficiency
and
performance.
These
included
load/
rinse
direction,
requirement
for
the
presence
of
sodium
ions,
temperature,
rinse
solution
volume
and
concentration,
wash
solution
volume
and
concentration,
optimization
in
the
synthetic
sample
matrix,
and
determination
of
concentrator
column
trapping
capacity.

2.3.1
Direction
of
Load
and
Rinse
Solutions
The
retention
time
(
RT)
and
peak
shape
for
perchlorate
were
not
the
same
when
a
rinse
step
(
to
remove
the
interfering
anions)
was
incorporated.
The
RT
was
marginally
shorter
and
the
peak
shape
broader
when
the
rinse
step
was
included.
This
was
somewhat
surprising
but
it
was
finally
determined
that
the
normal
instrument
configuration
loaded
the
sample
loop
in
one
direction
and
eluted
the
sample
from
the
sample
loop
in
the
opposite
direction.
When
the
concentrator
column
was
placed
in
the
sample
loop
position,
the
concentrated
perchlorate
was
pushed
back
on
the
concentrator
column
during
the
rinse
step
and
therefore,
could
experience
band
broadening
on
the
concentrator
column
compared
to
when
no
rinse
step
was
included.
As
shown
in
Figures
1
and
2,
this
problem
was
circumvented
by
changing
the
ports
on
the
load/
inject
valve
so
that
the
load
and
rinse
flows
were
in
the
same
direction.
TSC­
02­
0442
7
Figure
1.
Comparison
of
Direction
of
Load
and
Rinse
Solutions
Figure
2.
Comparison
of
Direction
of
Load
and
Rinse
Solutions
Instrument
Offset
to
Account
for
CO3
in
the
LiOH
Eluent
0
2.50
5.00
7.50
10.00
12.50
15.00
17.50
20.00
Minutes
µ
S
ClO4
­
load
&
elute
in
same
direction
ClO4
­
load
&
elute
in
opposite
direction
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
32.0
4.0
10
in
opposite
direction
peak
area
=
0.3595
uS*
min
10
in
same
direction
peak
area
=
0.4152
uS*
min
µ
S
min
21
ClO4
­

1.0
2.0
­
0.20
3.0
ug/
L
ClO
4
­
in
50
mg/
L
HCO
3
­
LSSM
ug/
L
ClO
4
­
in
50
mg/
L
HCO
3
­
LSSM
TSC­
02­
0442
8
2.3.2
Comparison
of
Perchlorate
Peak
Shape
at
Room
Temperature
and
35

C
As
shown
in
Figure
3,
the
peak
shape
for
perchlorate
was
better
at
35

C
compared
to
room
temperature.
Consequently,
35

C
was
used
for
all
further
studies.

Figure
3.
Effect
of
Temperature
on
Perchlorate
Chromatography
2.3.3
Use
of
Sodium
Ion
to
Improve
Trapping
Efficiency
The
Cryptand
concentrator
capacity
is
established
by
the
cation
counter
ion;
it
is
the
presence
of
sodium
that
establishes
the
capacity
of
the
concentrator
column.
This
is
illustrated
in
Figure
4,
where
the
concentrator
column
is
used
with
and
without
50
mg/
L
of
sodium
counter
ion.
Consequently,
50
mg/
L
of
the
LSSM
(
made
with
the
sodium
salts)
was
added
to
all
RW
and
Field
Samples
prior
to
analysis.
35C
peak
area
=
42750
ClO4
RT
=
6:
23
0
2.00
4.00
6.00
8.00
10.00
12.00
Minutes
­
0.20
0
0.20
0.40
0.60
0.80
1.00
µ
S
Room
temp
peak
area
=
28365
ClO
4
­
RT
=
9:
70
35

C
peak
area
=
46323
ClO
4
­
RT
=
6:
23
TSC­
02­
0442
9
Figure
4.
Use
of
Sodium
to
Improve
Perchlorate
Peak
Shape
2.3.4
Concentration
and
Volume
of
Rinse
Solution.

The
rinse
solution
is
a
dilute
NaOH
solution
that
is
placed
in
the
second
autosampler
vial
for
all
samples
to
be
injected
and
is
used
to
rinse
any
other
interfering
anions
that
are
trapped
on
the
concentrator
column
and
send
them
to
waste
while
the
perchlorate
is
retained
on
the
concentrator
column.
As
indicated
in
Figure
5,
the
baseline
is
lowest
(
most
complete
removal
of
other
anionic
species)
and
the
peak
shape
for
perchlorate
is
best
(
most
symmetrical
and
least
tailing)
when
incorporating
the
rinse
step
using
1.0
mL
of
10
mM
NaOH.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
­
0.50
­
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
µ
S
min
1
RW
10
ug/
L
ClO
4
­
+
50
mg/
L
Na+

peak
area
0.200
RW
10
ug/
LClO
4
­

peak
area
0.101
MA
Offset
TSC­
02­
0442
10
Figure
5.
Comparison
of
Rinse
Volume
2.3.5
Concentration
and
Volume
of
Wash
Solution
During
the
preliminary
work
on
this
method,
the
peak
shape
for
perchlorate
was
always
quite
broad.
This
was
speculated
to
be
attributed
to
the
band
broadening
occurring
during
the
concentration,
rinse
and
elution
cycles.
It
was
speculated
that
a
very
weak
wash
solution
(
e.
g.,
0.50
mM
NaOH)
could
be
used
to
wash
the
perchlorate
off
the
concentrator
and
refocus
it
at
the
head
of
the
guard
column
prior
to
increasing
the
eluent
strength
to
separate
the
perchlorate
on
the
analytical
column.
This
was
evaluated
by
removing
the
guard
and
analytical
columns
from
the
system
and
connecting
the
concentrator
column
directly
to
the
conductivity
detector
to
observe
the
time
at
which
all
the
perchlorate
was
eluted
from
the
column.
In
our
studies,
the
perchlorate
was
completely
washed
off
the
concentrator
column
in
about
9
minutes.
A
12­
minute
wash
step
was
incorporated
into
the
method
to
ensure
complete
removal
of
perchlorate
and
the
lowest
background
conductivity
before
starting
to
separate
and
quantify
perchlorate.
As
indicated
in
Figure
6,
essentially
no
difference
was
observed
in
the
peak
area
using
a
15
minute
wash
time
in
the
1000
mg/
L
LFSSM
and
therefore
a
12
minute
wash
time
was
incorporated
into
the
new
method.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
32.0
321
3.0
3.0
ug/
L
ClO4
­
in
1000
mg/
L
HCO3
­
LSSM
no
rinse
peak
area
=
0.0547
uS*
min
3.0
ug/
L
ClO4
­
in
1000
mg/
L
HCO3
­
LSSM
0.50
mL
rinse
peak
area
=
0.0682
uS*
min
ug/
L
ClO4
­
in
1000
mg/
L
HCO
3
­
LSSM
1.0
mL
rinse
peak
area
=
0.0637
uS*
min
ClO4
­

­
0.20
0.50
1.0
1.5
2.0
2.5
3.0
3.5
4.0
µ
S
min
TSC­
02­
0442
11
Figure
6.
Comparison
of
12
and
15
Minute
Wash
Time
2.3.6
Optimization
in
the
Synthetic
Sample
Matrix
EPA
Method
314.0
incorporated
a
synthetic
sample
matrix
containing
1000
mg/
L
of
chloride,
carbonate
and
sulfate.
In
the
development
of
this
method,
it
was
determined
that
the
pH
of
the
synthetic
matrix
used
in
Method
314.0
was
approximately
10.0
­­
an
unlikely
pH
to
be
experienced
in
normal
finished
drinking
water
matrices.
As
well,
injection
of
a
large
volume
of
solution
at
this
pH
has
the
potential
to
affect
the
chromatography
in
the
synthetic
sample
matrices
by
increasing
the
eluent
strength
and
shortening
the
retention
time
for
perchlorate.
When
carbonate
was
replaced
with
bicarbonate
in
the
1000
mg/
L
LSSM,
the
pH
of
this
solution
was
only
8.6.
This
is
a
more
realistic
upper
pH
for
a
finished
drinking
water.
As
shown
in
Figure
7,
the
peak
area
for
perchlorate
is
approximately
20%
lower
in
the
carbonate
LSSM
compared
to
the
bicarbonate
LSSM.
The
loss
in
peak
area
is
likely
due
to
the
carbonate
increasing
the
eluent
strength
and
the
loss
of
some
perchlorate
with
the
other
interfering
anions.
As
shown
in
Figure
8,
when
the
bicarbonate
LSSM
was
adjusted
to
pH
10
prior
to
loading,
the
concentrator
column
capacity
was
exceeded
sooner
(
e.
g.,
less
perchlorate
was
trapped)
with
the
bicarbonate
LSSM
at
pH
10
than
at
its
normal
pH
of
8.6.
Consequently,
1000
mg/
L
of
bicarbonate
was
used
to
replace
the
1000
mg/
L
carbonate
in
the
LSSM
in
EPA
Method
314.1.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
32.0
35.0
­
0.20
1.0
2.0
3.0
4.0
15
ug/
LClO4
­
in
1000
mg/
L
LSSM
12
min
peak
area
=
0
.4321
uS*
min
15
ug/
LClO4
­
in
1000
mg/
L
LSSM
15
min
peak
area
=
0.4187
uS*
min
µ
S
min
21
ClO
4
­
TSC­
02­
0442
12
Figure
7.
Comparison
of
HCO3
­
vs.
CO3
2­
LSSM
Figure
8.
Comparison
of
Trapping
Efficiency
10

g/
L
ClO4
­
in
HCO3
­
LSSM
at
pH
8.6
and
10
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
32.0
­
0.20
1.0
2.0
3.0
4.0
10
ug/
LClO4
­
in
1000
mg/
L
CO3
­
­
in
1000
mg/
L
HCO3
­
LSSM
peak
area
=
0.3194
uS*
min
µ
S
min
2
Offset
10%
for
clarity
ClO
4
­

2­
LSSM
peak
area
=
0.2629
uS*
min
10
ug/
LClO4
0.0000
0.1000
0.2000
0.3000
0.4000
0.5000
Control
50mL
in
50
LSSM
1
2
3
4
5
mL
Loaded
Peak
Area
(
uS*
Min)

pH
=
8.6
pH
=
10.0
5
mL
in
TSC­
02­
0442
13
2.3.7
Concentrator
Column
Trapping
Capacity
Because
of
the
potential
for
very
high
ionic
matrices
to
affect
the
chromatography
of
perchlorate,
an
80%
restriction
was
placed
on
the
trapping
capacity
of
the
concentrator
column
to
ensure
that
the
trapping
capacity
of
the
concentrator
column
would
not
be
exceeded
when
analyzing
very
high
ionic
strength
drinking
water
matrices.
Prior
to
use,
the
capacity
of
the
concentrator
column
was
evaluated
to
ensure
that
not
more
than
80%
of
the
capacity
of
the
concentrator
column
was
exceeded
by
loading
successive
volumes
of
a
5.0
µ
g/
L
perchlorate
standard
in
the
1000
mg/
L
LFSSM
and
observing
when
break­
through
occurs
(
i.
e.,
no
further
increase
in
observed
peak
area
or
concentration).
Based
on
the
results
presented
in
Figure
9,
a
3­
mL
injection
volume
was
chosen
for
the
method.

Figure
9.
Column
Capacity
Determination
for
Perchlorate
in
a
1000
mg/
L
LSSM
3.
PRELIMINARY
EVALUATION
OF
314.1
PROTOCOLS
After
optimizing
the
preceding
parameters,
a
preliminary
evaluation
of
the
new
Method
314.1
protocols
with
the
AS16
analytical
column
was
initiated.
As
indicated
in
Figure
10,
it
was
established
that
acceptable
performance
(
similar
peak
areas)
could
be
obtained
for
perchlorate
in
the
50,
500
and
1000
mg/
L
LFSSMs
using
a
3­
mL
injection
volume
with
a
1­
mL
rinse
volume
of
10
mM
NaOH.
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
Control
5
mL
in
50
LSSM
1
2
3
4
5
mL
Injected
Peak
Area
(
uS*
min)
TSC­
02­
0442
14
Figure
10.
Comparison
of
3.0
µ
g/
L
ClO4
­
in
50,
500
and
1000
mg/
L
LSSM
The
next
step
involved
calibration
using
calibration
standards
ranging
from
0.20
to
15
µ
g/
L
ClO4
­
in
the
50
mg/
L
LFSSM.
As
indicated
in
Figure
11,
acceptable
correlation
coefficients
(
0.9999
to
0.9977)
were
obtained
for
calibration
curves
ranging
from
0.20
to
15
µ
g/
L
ClO4
­
in
50,
500
and
1000
mg/
L
LFSSMs.

Figure
11.
Calibration
of
0.20
to
15
µ
g/
L
ClO4
­
in
50,
500
and
1000
mg/
L
LSSM
0.000
0.100
0.200
0.300
0.400
0.00
5.00
10.0015.0020.00
Concentration
(
ug/
L)
Peak
Area
(
uS*
Min)

50
HIW
R2
=
0.9999
500
HIW
R2
=
0.9992
100
HIW
R2
=
0.9977
LSSM
LSSM
1000
LSSM
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
­
0.20
1.0
2.0
3.0
4.0
3.0
ug/
L
ClO4
­
in
50
mg/
L
LSSM
peak
area
=
0.0666
uS*
min
3.0
ug/
L
ClO4
­
in
500
mg/
L
LSSM
peak
area
=
0.0660
uS*
min
3.0
ug/
L
ClO4
­
in
1000
mg/
L
LSSM
peak
area
=
0.0611
uS*
min
µ
S
min
321
ClO
4
­
TSC­
02­
0442
15
As
shown
in
Figure
12,
acceptable
peak
shape
and
area
was
obtained
for
a
0.20
µ
g/
L
ClO4
­

fortification
level
in
the
50
mg/
L
LSSM.

Figure
12.
0.20
µ
g/
L
ClO4
­
in
50
mg/
L
LSSM
Preliminary
results
with
the
new
protocols
were
very
encouraging.
However,
there
was
still
a
desire
to
identify
a
surrogate
to
monitor
the
trapping
efficiency
of
the
concentrator
column.
The
next
phase
of
the
project
involved
the
search
for
a
suitable
surrogate
for
the
new
Method
314.1.

4.
EVALUATION
OF
SURROGATES
FOR
AS16
COLUMNS
Because
of
the
complexity
of
any
sample
pre­
concentration/
matrix
elimination
technique,
it
is
desirable,
if
at
all
possible,
to
include
a
surrogate
in
the
method
to
monitor
the
efficiency
of
the
trapping
and
releasing
of
the
analyte
of
interest
from
the
concentrator
column.
The
ideal
surrogate
would
concentrate
and
elute
from
the
concentrator
column
in
a
similar
manner
to
perchlorate
and
would
have
similar
chromatographic
characteristics
to
perchlorate
on
the
analytical
column,
thereby
allowing
quality
control
(
QC)
protocols
to
be
developed
to
ensure
that
Data
Quality
Objectives
(
DQOs)
are
met.
Several
compounds
were
evaluated
as
potential
surrogates.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
32.0
­
0.20
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
LCMRL
0.20ug/
L
ClO
4
­
in
50
mg/
L
HCO
3
­
LSSM
peak
area
=
0.0049uS*
min
µ
S
min
ClO
4
­
TSC­
02­
0442
16
Since
all
of
the
potential
surrogates
contained
a
benzene
ring
structure,
an
absorbance
detector
was
connected,
after
the
conductivity
detector,
to
provide
an
additional
tool
for
monitoring
the
surrogate.
Although
several
compounds
were
evaluated,
no
suitable
surrogate
was
found.
The
complete
details
and
the
reasons
for
the
failure
of
each
component
are
beyond
the
scope
of
this
report.
However,
a
brief
description
of
the
individual
components
evaluated
and
the
reasons
for
their
failure
is
included
below.

4.1
MELLITIC
ACID
(
MA)

Preliminary
work
with
MA
indicated
that
this
component
worked
well
when
using
the
Cryptand
concentrator
column
with
the
Cryptand
guard
and
analytical
columns
but
was
too
strongly
retained
and
not
eluted
from
the
AS16
columns
with
the
optimized
experimental
protocols
developed
for
EPA
Method
314.1.

4.2
BENZENESULFONIC
ACID
(
BSA)

Benzenesulfonic
acid
was
evaluated
for
its
potential
as
a
surrogate.
Although
concentrated
effectively
on
the
concentrator
column,
BSA
eluted
with
the
void
volume
on
the
analytical
column
and
therefore
was
not
acceptable
as
a
surrogate.

4.3
4­
CHLOROBENZENESULFONIC
ACID
(
4­
Cl
BSA)

Although
4­
CL
BSA
has
the
potential
to
coelute
with
perchlorate
on
the
AS16
columns
using
EPA
Method
314.0
protocols,
separation
of
the
two
components
is
achieved
with
the
sample
pre­
concentration/
matrix
elimination
protocols
developed
for
EPA
Method
314.1.
However,
the
presence
of
a
large
concentration
of
4­
Cl
BSA
as
a
surrogate,
which
would
be
required
to
prevent
QC
failures
if
low
concentrations
of
4­
Cl
BSA
were
present
in
any
field
samples,
would
have
the
potential
to
interfere
with
the
quantitation
of
trace
levels
of
perchlorate.
Consequently,
4­
Cl
BSA
was
not
acceptable
as
a
surrogate
for
Method
314.1.

4.4
TRIFLUROBENZOIC
ACIDS
(
TFBA)

Three
different
isomers
2,3,4­,
2,4,5­
and
3,4,5­
TFBA,
were
evaluated
for
their
potential
to
serve
a
role
as
the
surrogate
for
Method
314.1.
The
2,3,4­
and
2,4,5­
TFBA
isomers
eluted
with
the
void
volume
on
the
analytical
column
while
the
3,4,5­
isomer
did
not
provide
acceptable
perchlorate/
surrogate
recovery
ratios.
Consequently,
these
components
were
eliminated
as
potential
surrogates
for
EPA
Method
314.1.

4.5
5­
SULFOSALICYLIC
ACID
(
SSA)

The
SSA
was
not
strongly
retained
on
the
concentrator
column
and
experienced
significant
loss
during
the
rinse
step.
Consequently,
SSA
was
eliminated
as
a
potential
surrogate
for
EPA
Method
314.1.

4.6
DINITROBENZOIC
ACID
(
DNBA)

The
potential
to
use
DNBA
as
a
surrogate
showed
the
most
promise
and
provided
very
good
resolution
from
perchlorate
and
response
on
both
the
conductivity
and
absorbance
detectors
as
shown
in
Figures
13
and
14.
TSC­
02­
0442
17
Figure
13.
Conductivity
Chromatogram
of
ClO4
­,
4­
Cl­
BSA
and
DNBA
Figure
14.
Absorbance
Chromatogram
of
ClO4
­,
4­
Cl
BSA
and
DNBA
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.7
­
0.05
0.00
0.05
0.10
0.15
0.20
0.25
10
ug/
L
ClO4
­
+
200ug/
L
4­
Cl
BSA
+
100
ug/
L
DNBA
in
1000
LSSM
AU
min
4­
Cl
BSA
­
25.7
DNBA
­
28.8
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
31.0
­
0.50
1.0
2.0
3.0
4.0
10
ug/
L
ClO4
­
+
200
ug/
L
4­
Cl
BSA
+
100
ug/
L
DNBA
in
1000
LSSM
µ
S
min
ClO4
­
­
24.5
4­
Cl
BSA
­
25.5
DNBA
­
28.5
TSC­
02­
0442
18
However,
further
evaluation
indicated
that
although
DNBA
did
not
break
through
on
the
concentrator
column,
it
appeared
that
DNBA
was
tying
up
some
of
the
sites
on
the
concentrator
column
and
perchlorate
was
not
being
effectively
retained
on
the
concentrator
column.
Consequently,
DNBA
was
eliminated
as
potential
surrogates
for
EPA
Method
314.1.

Once
it
was
established
that
it
would
be
very
unlikely
to
find
a
surrogate
for
a
EPA
Method
314.1
that
would
behave
similarly
to
perchlorate
on
both
the
concentrator
and
primary
and
confirmation
columns,
the
only
alternative
was
to
develop
QC
protocols
that
would
ensure
detection
of
any
and
all
failures
in
the
trapping
efficiency
and
chromatography
of
perchlorate.
As
a
result,
two
types
of
Continuing
Calibration
Check
(
CCC)
Standards
were
added
to
the
method:
CCCs
prepared
in
reagent
water;
and
CCCs
prepared
in
the
LSSM.

5.
EVALUATION
OF
THE
CRYPTAND
ANALYTICAL
COLUMN
The
use
of
confirmation
columns
to
minimize
the
reporting
of
false
positives
is
a
technique
that
has
commonly
been
used
with
gas
and
liquid
chromatographic
methods
that
use
detectors
other
than
mass
spectrometry.
The
idea
behind
this
technique
is
to
provide
a
different
separation
mechanism
with
the
confirmation
column,
thereby
minimizing
the
possibility
that
any
interference
could
coelute
with
the
analyte
of
interest
on
both
columns.
This
technique
was
to
be
incorporated
into
EPA
Method
314.1.

The
Cryptand
columns
developed
by
Dionex
offered
a
unique
potential
to
be
used
for
the
confirmation
method.
Normal
ion
chromatographic
(
IC)
methods
involve
ion
exchange
as
the
mode
of
separation
with
fixed
capacity
separators.
The
Cryptand
columns,
on
the
other
hand,
use
manipulation
of
column
capacity
as
part
of
the
mechanism
for
separation,
as
discussed
above.
The
cation
counter
ion
in
the
eluent
has
a
strong
influence
on
both
the
column
capacity
and
the
capacity
modification
kinetics.

5.1.
SEPARATION
OF
4­
Cl
BSA
ON
THE
CRYPTAND
ANALYTICAL
COLUMN
As
mentioned
previously,
4­
Cl
BSA
is
a
component
that
was
identified
(
IC­
MS)
in
groundwater.
Under
EPA
Method
314.0
conditions,
it
coelutes
with
perchlorate
on
the
AS16
analytical
column.
When
using
the
appropriate
conditions,
the
Cryptand
columns
were
shown
to
have
the
ability
to
resolve
perchlorate
and
4­
Cl
BSA.
1
5.2.
USE
OF
LITHIUM
AND
SODIUM
HYDROXIDE
ELUENTS
With
the
Cryptand
columns,
the
counter
ion
can
be
used
to
manipulate
the
capacity
of
the
column.
The
concentration
of
the
counter
ion
has
a
similar
effect.
For
example,
a
sodium
ion
sets
a
much
higher
column
capacity
than
lithium.
Therefore,
the
species
of
counter
ion
and
its
concentration
can
be
manipulated
to
effectively
concentrate
the
perchlorate
on
the
Cryptand
concentrator
column
and
then
effect
separation
on
the
Cryptand
analytical
column.
Consequently,
a
two
eluent
system
(
sodium
and
lithium
hydroxide)
must
be
used
with
the
Cryptand
analytical
column.
Because
a
sodium
cartridge
was
available
for
the
EG50,
the
preliminary
work
with
the
Cryptand
analytical
column
used
manuallyprepared
lithium
hydroxide
eluents.
TSC­
02­
0442
19
5.2.1.
Need
for
ATC
trap
Column
to
Remove
Carbonate
Lithium
hydroxide,
as
a
granular
material,
appears
to
be
even
more
susceptible
to
carbonate
formation
due
to
exposure
to
the
atmosphere
than
sodium
hydroxide.
Consequently,
a
ATC
trap
column
must
be
used
to
remove
carbonate
from
the
LiOH
eluent
in
order
to
maintain
consistent
chromatography.
This
technology
is
somewhat
cumbersome
as
it
requires
that
the
trap
column
be
frequently
removed
from
the
system
and
regenerated.

Even
with
the
ATC
trap
column
in
place,
a
shift
in
baseline
was
observed
shortly
after
the
switch
from
the
sodium
to
lithium
eluents.
As
shown
in
Figure
4,
the
rise
in
baseline
of
approximately
2.5
µ
S,
which
was
attributed
to
the
presence
of
carbonate
in
the
eluent,
was
negated
using
an
instrument
offset
at
8.5
minutes
to
allow
for
better
visual
detection
of
trace
levels
of
perchlorate.

6.
IMPROVING
METHOD
ROBUSTNESS
 
PHASE
1
Studies
on
both
the
primary
AS16
and
confirmation
Cryptand
columns
were
being
conducted
simultaneously
in
both
EPA
and
Dionex
laboratories.
Having
established
the
preliminary
optimal
operating
conditions
and
QC
requirements
for
the
AS16
column,
an
attempt
to
generate
the
precision
and
accuracy
data
was
initiated.

6.1
DETERMINATION
OF
LCMRL
The
Lowest
Concentration
Minimum
Reporting
Level
(
LCMRL)
was
determined
according
to
a
procedure
described
elsewhere.
2
Using
unfiltered
samples
to
determine
the
LCMRL,
very
promising
results
were
obtained
and
a
LCMRL
of
approximately
0.13
µ
g/
L
was
calculated
for
ClO4
­
in
the
50
mg/
L
LFSSM.

6.2
STERILE
FILTRATION
Perchlorate,
under
certain
conditions,
can
be
subject
to
microbial
degradation.
Consequently,
a
sterile
filtration
step
was
included
in
the
sample
collection
protocols
for
this
method.

6.2.1
Background
Confirmation
from
Sterile
Filtration
Devices
When
the
LCMRL
was
repeated
incorporating
the
sterile
filtration
procedure,
unacceptable
recoveries
and
precisions
were
observed.
As
a
result,
a
much
higher
LCMRL
(
0.57
µ
g/
L)
was
reported.
Eventually
the
problem
was
traced
to
the
sterile
storage
containers
which
appeared
to
leach
out
a
contaminant
that
increased
the
background
conductivity
to
almost
2.0
µ
S*
min
when
perchlorate
was
eluting
compared
to
about
0.50
µ
S*
min
in
the
unfiltered
samples.
Consequently,
as
shown
in
Figure
15,
trace
levels
of
perchlorate
were
very
hard
to
detect
in
the
sterile
filtered
samples
by
conductivity
detection.
This
problem
was
eliminated
by
replacing
the
sterile
containers
with
an
I­
Chem
125­
mL
sterile
HDPE
bottle
(
Fisher
Cat.
No.
N411­
0125
or
equivalent).
TSC­
02­
0442
20
Figure
15.
Increase
in
Background
Conductivity
with
Time
(
0.30

g/
L
ClO4
­
in
50
mg/
L
LSSM
in
Sterile
Container
for
1,
4
and
7
Days)

6.3
INCREASING
ELUENT
CONCENTRATION
FROM
50­
mM
TO
65­
mM
NaOH
After
establishing
the
proper
sterile
filtration
protocols,
the
analysis
of
12
samples
over
9
hours
indicated
that
occasionally,
quantitation
problems
were
being
experienced
as
the
result
of
something
else
eluting
in
the
RT
window
for
perchlorate.
Although
the
precision
was
acceptable
(%
RSD
=
6.9),
the
potential
for
a
sample
to
be
lost
due
to
carryover
from
a
previous
sample
required
further
study.
Increasing
the
eluent
strength,
increasing
the
flow
rate
and
extending
the
run
time
are
ways
to
help
ensure
that
all
components
are
eluted
from
the
analytical
column
prior
to
initiating
the
next
run.

Increasing
the
flow
rate
caused
the
perchlorate
to
elute
closer
to
the
void
volume.
This
made
integration
difficult
and
was
not
an
acceptable
alternative.
Extending
the
run
time
on
a
45
minute
analysis
time
also
did
not
seem
to
be
an
attractive
alternative.
On
the
other
hand,
increasing
the
eluent
strength
from
50­
to
65­
mM
NaOH
for
the
separation
and
quantitation
of
perchlorate
only
raised
the
background
conductivity
marginally
and
kept
the
perchlorate
peak
well
away
from
the
trailing
edge
of
the
other
eluting
anions
while
marginally
improving
the
peak
shape
and
peak
area
for
perchlorate.
Consequently,
65­
mM
NaOH
at
a
flow
rate
of
0.25
mL
per
minute
became
the
eluent
for
the
new
method.
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
24.0
26.0
28.0
30.0
­
0.30
1.0
2.0
3.0
4.0
5.0
6.0
µ
S
min
321
Day
7
Day
4
Day
1
Background
increases
with
days
in
sterile
container
ClO4
­
TSC­
02­
0442
21
6.4
CARRYOVER
IN
GROUNDWATER
COMPARED
TO
SURFACE
WATER
With
the
new
eluent
conditions,
as
shown
in
Figure
16,
a
very
acceptable
precision
of
5.8
%
RSD
(
n=
27
over
21
hours)
was
obtained
for
a
0.50
µ
g/
L
ClO4
­
fortification
of
a
chlorinated
surface
water
that
contained
50
mg/
L
of
the
LSSM.

Figure
16.
Chlorinated
Surface
Water
Precision
for
0.50

g/
L
ClO4
­
in
50
mg/
L
LSSM
(
n=
27
over
21
hours)

However,
when
the
same
experiment
was
repeated
using
a
chloraminated
ground
water,
significant
problems
were
encountered.
As
shown
in
Figure
17,
unacceptable
precision
of
29.6
%
RSD
(
n=
27
over
21
hours)
was
obtained
for
a
0.50
µ
g/
L
ClO4
­
fortification
to
a
chloraminated
groundwater
containing
50
mg/
L
of
the
LSSM.
Again,
the
background
conductivity
increased
during
the
analysis
and
rose
above
2.5
µ
S*
minute
when
perchlorate
was
eluting,
making
quantitation
of
the
trace
level
of
perchlorate
extremely
difficult.
0.000
0.010
0.020
1
4
7
10
13
16
19
22
25
Replicate
Peak
Area
(
uS*
min)

0.030
TSC­
02­
0442
22
Figure
17.
Chloraminated
Groundwater
Precision
for
0.50

g/
L
ClO4
­
in
50
mg/
L
LSSM
(
n=
27
over
21
hours)

It
was
felt
that
the
method
needed
to
be
further
optimized
to
eliminate
the
build
up
of
the
material
that
was
causing
the
conductivity
to
increase
during
the
analysis
sequence
with
normal
drinking
water
matrices.

6.5
ADDITION
OF
A
100­
mM
NaOH
COLUMN
CLEANING
STEP
It
was
determined
that
by
adding
a
step
from
65­
to
100­
mM
NaOH
just
after
perchlorate
elutes
from
the
analytical
column,
and
continuing
the
cleaning
step
for
the
first
8
minutes
of
the
sample
loading
step,
no
carry­
over
was
observed
in
the
chloraminated
groundwater
sample.
As
shown
in
Figure
18,
acceptable
precision
of
12.7
%
RSD
(
n=
27
over
36
hours)
was
obtained
for
a
0.50
µ
g/
L
ClO4
­
fortification
to
the
same
(
Sect.
6.4)
chloraminated
groundwater
containing
50
mg/
L
of
the
LSSM.
A
power
interruption
during
the
run
at
sample
14
caused
about
a
15­
hour
delay
in
the
analysis
program.
0.000
0.010
0.020
0.030
1
4
7
10
13
16
19
22
25
Replicates
Peak
Area
(
uS*
min)
TSC­
02­
0442
23
Figure
18.
Chloraminated
Ground
Water
Precision
for
0.50

g/
L
ClO4
­
in
50
mg/
L
LSSM
(
n=
27
over
36
hours)

7.
DEVELOPMENT
OF
DUAL
ELUENT
GENERATION
As
mentioned
previously,
development
of
the
Cryptand
confirmation
column
work
was
progressing
simultaneously.
The
focus
of
this
phase
of
the
development
work
was
to
circumvent
the
baseline
fluctuation
attributed
to
the
presence
of
carbonate
in
the
manually
prepared
lithium
hydroxide
eluent
(
Sect.
5.2).
Eluent
generation
using
a
potassium
hydroxide
eluent
combined
with
a
Continuously
Regenerated
Anion
Trap
Column
(
CR­
ATC)
to
continually
remove
carbonate
from
the
eluent
is
a
technique
developed
by
Dionex.
The
second
phase
of
their
work
involved
development
of
a
sodium
hydroxide
cartridge
to
generate
sodium
hydroxide
eluents.
The
sodium
hydroxide
eluent
was
required
for
EPA
Method
314.1
use
of
the
Cryptand
concentrator
column
in
combination
with
the
AS16
analytical
column.

The
next
step
was
to
determine
if
it
was
a
viable
option
to
use
a
lithium
hydroxide
cartridge
with
the
Cryptand
columns
and
then
to
determine
if
a
dual
column
eluent
generator
could
be
developed
to
support
the
Cryptand
confirmation
column
work
for
EPA
Method
314.1.
The
development
of
the
dual
eluent
generator
progressed
very
well
but
the
extremely
tight
time
constraints
for
completion
of
the
development
phase
for
EPA
Method
314.1
required
that
a
parallel
search
for
an
alternative
confirmation
column
be
initiated.
Both
of
these
projects
were
successfully
completed.
The
optional
AS20
confirmation
column
utilized
the
same
eluent
as
the
primary
AS16
column,
which
significantly
simplified
the
method
protocols
and
therefore,
was
incorporated
into
EPA
Method
314.1.
Although
beyond
the
scope
of
this
Research
0.000
0.010
0.020
0.030
1
4
7
10
13
16
19
22
25
Replicates
Peak
Area
(
uS*
min)
#
14
liquid
on
top
of
sample
vial;
sample
did
not
inject
TSC­
02­
0442
24
Summary,
successful
completion
of
the
development
of
the
dual
cartridge
eluent
generator
proved
to
be
an
integral
and
vital
addition
for
Cryptand
column
analyses.

8.
INITIAL
ASSESSMENT
OF
P&
A
DATA
WITH
THE
AS16
COLUMN
After
modifying
and
re­
establishing
the
optimal
operating
protocols
for
the
AS16
column,
collection
of
the
precision
and
accuracy
data
with
the
AS16
analytical
column
was
repeated.

8.1
METHOD
PROTOCOLS
FOR
AS16
COLUMN
The
finalized
conditions
incorporated:
 
the
addition
of
50
mg/
L
LSSM
to
all
samples
 
eluent
flow
rate
of
0.25
mL/
minute
 
3.0
mL
loading
volume
 
1.0
mL
of
10
mM
NaOH
rinse
solution
 
0.50
mM
NaOH
to
wash
the
perchlorate
off
the
concentrator
column
and
refocus
it
at
the
head
of
the
AG16
column
 
65
mM
NaOH
to
separate
the
perchlorate
on
the
AS16
columns
 
100
mM
NaOH
immediately
after
the
elution
of
perchlorate
to
clean
the
AS16
columns
and
set
the
capacity
of
the
Cryptand
trap
column
for
the
next
analysis
8.2
LCMRL
AND
P&
A
RESULTS
With
the
new
operating
protocols,
including
sterile
filtration
of
the
samples,
the
results
for
the
LCMRL
were
very
encouraging
with
a
calculated
value
of
approximately
0.13
µ
g/
L
for
perchlorate.
The
various
P&
A
matrices
were
fortified
(
n=
7)
with
0.50,
1.0
and
5.0
µ
g/
L
perchlorate,
and
as
shown
in
Table
1,
the
precision
and
accuracy
were,
in
general,
acceptable
in
the
50
and
1000
mg/
L
LFSSM,
a
chlorinated
ground
water,
a
chlorinated
surface
water
and
a
chloraminated
surface
water.
TSC­
02­
0442
25
TABLE
1.
Precision
and
Accuracy
Data
for
EPA
Method
314.1
with
AS16
Column
Native
Spike
Spike
Spike
%
%
Matrix
(
µ
g/
L)
0.5
µ
g/
L
1.0
µ
g/
L
5.0
µ
g/
L
REC
RSD
50
mg/
L
LFSSM
0.392
78.4
4.1
1000
mg/
L
LFSSM
0.475
94.9
7.3
50
mg/
L
LFSSM
5.02
100
1.9
1000
mg/
L
LFSSM
5.36
107
5.4
Chlorinated
GW
<
0.50
Chlorinated
GW
1.11
111
5.1
Chlorinated
GW
5.39
108
5.3
Chlorinated
SW
0.602
4.3
Chlorinated
SW
1.64
104
2.8
Chlorinated
SW
6.56
120
2.2
High
Organic
Water
0.421
7.1
High
Organic
Water
1.52
109
4.9
High
Organic
Water
6.62
124
2.7
Chloraminated
SW
<
0.50
Chloraminated
SW
0.877
87.7
3.6
Chloraminated
SW
5.87
117
4.6
The
preliminary
precision
(
1.9
to
7.3%
RSD)
and
accuracy
(
78.4
to
124%
recovery)
results
were
very
encouraging.

8.3
COMPARATIVE
STUDY
USING
EPA
METHOD
314.1
AND
331.0
Following
the
encouraging
results
with
the
primary
AS16
column,
the
next
step
was
to
evaluate
EPA
Method
314.1
against
the
new
LC­
MS­
MS
method
(
EPA
Method
331.0)
using
actual
drinking
water
samples.
Fifteen
different
municipal
drinking
water
samples
(
ground
and
surface)
were
analyzed
for
their
native
level
of
perchlorate
and
then
fortified
with
0.50,
2.0
and
5.0
µ
g/
L
perchlorate
and
reanalyzed
using
the
two
new
perchlorate
methods.

As
shown
in
Table
2,
excellent
agreement
between
the
two
methods
was
obtained
for
the
9
of
the
15
samples
that
had
positive
hits
for
perchlorate
concentrations
above
0.30
µ
g/
L.
TSC­
02­
0442
26
TABLE
2.
Precision
and
Accuracy
for
EPA
Method
314.1
with
AS16
Column
Sample
314.1
µ
g/
L
ClO4
­
331.0
µ
g/
L
ClO4
­

2
0.42
0.43
7
0.39
0.37
8
0.45
0.50
9
0.31
0.35
10
0.43
0.57
11
0.77
0.85
12
2.07
2.03
14
0.58
0.71
15
0.00
0.39
Although
the
native
levels
were
in
very
good
agreement,
the
fortification
recoveries
with
EPA
Method
314.1
were
higher
than
anticipated,
especially
in
the
2.0
and
5.0
µ
g/
L
fortification
levels
(%
recoveries
of
114
to
140%
and
111
to
147%
respectively).
The
high
recoveries
in
the
drinking
water
fortifications
were
puzzling,
especially
in
light
of
the
fact
that
the
fortification
recoveries
were
acceptable
in
the
high
ionic
LFSSM
and
therefore
suggested
that
the
method,
as
developed,
was
not
performing
well
in
the
drinking
water
matrices.
This
was
addressed
further
in
Section
10
below.

9.
DEVELOPMENT
AND
EVALUATION
OF
AS20
CONFIRMATION
COLUMN
The
goal
was
to
find
a
confirmation
column
with
a
separation
mechanism
that
is
sufficiently
different
from
that
of
the
primary
column
in
order
to
eliminate
potential
interferences.
The
suggested
primary
column,
the
IonPac
AS16,
has
a
column
chemistry
that
is
based
on
a
low
cross­
link
vinyl
aromatic
quaternary
monomer.
It
was
designed
to
provide
good
chromatographic
performance
for
polarizable
inorganic
anions
such
as
perchlorate
with
moderate
concentration
hydroxide
eluents.
Anionic
species
which
may
exhibit
retention
characteristics
similar
to
perchlorate
on
the
AS16
column
include
various
relatively
rare
aromatic
anionic
species.
Although
less
polarizable
than
inorganic
species
such
as
perchlorate,
such
aromatic
species
show
enhanced
retention
due
to
interaction
with
the
pi
electrons
of
the
aromatic
backbone.
The
suggested
confirmation
column,
the
IonPac
AS20,
has
a
column
chemistry
that
is
based
on
a
cross­
linked
quaternary
condensation
polymer
completely
free
of
any
pi
electron­
containing
substituents.
As
such,
it
exhibits
selectivity
for
polarizable
anions
that
is
complementary
to
the
AS16,
but
because
of
the
absence
of
any
pi
electron
character,
retention
of
aromatic
anionic
species
is
greatly
diminished
relative
to
that
of
the
AS16.

Because
the
AS20
confirmation
column
was
developed
with
many
similar
characteristics
to
the
primary
AS16
column,
optimization
of
the
operation
protocols
was
quite
simple
and
required
only
a
5
minute
increase
in
run
time
to
account
for
the
slightly
longer
RT
for
perchlorate
on
the
AS20
column.
Having
established
the
preliminary
optimal
operation
conditions
and
QC
requirements
for
the
AS20
column,
an
attempt
to
evaluate
the
precision
and
accuracy
of
this
column
was
initiated.
TSC­
02­
0442
27
9.1
LCMRL
AND
P&
A
RESULTS
With
the
optimized
operating
protocols
for
the
AS20
confirmation
column,
including
sterile
filtration
of
the
samples,
the
results
for
the
LCMRL
were
very
encouraging,
with
a
calculated
value
of
approximately
0.12
µ
g/
L
for
perchlorate.
The
various
P&
A
matrices
were
fortified
(
n=
7)
with
0.50,
1.0
and
5.0
µ
g/
L
perchlorate
and
as
shown
in
Table
3,
the
precision
and
accuracy
were
acceptable
in
the
50
and
1000
mg/
L
LFSSM,
but
again
showed
high
recoveries,
especially
at
the
1.0
and
5.0
µ
g/
L
fortification
levels,
in
the
chlorinated
surface
water
and
chloraminated
surface
water.

TABLE
3.
Precision
and
Accuracy
for
EPA
Method
314.1
with
AS20
Column
Native
Spike
Spike
Spike
%
%
Matrix
(
µ
g/
L)
0.5
µ
g/
L
1.0
µ
g/
L
5.0
µ
g/
L
REC
RSD
50
mg/
L
LFSSM
0.388
77.6
22.0
1000
mg/
L
LFSSM
0.549
110
5.89
50
mg/
L
LFSSM
4.65
93.1
10.3
1000
mg/
L
LFSSM
5.34
107
7.3
4.00
Chlorinated
SW
2.38
3.05
Chlorinated
SW
3.88
151
3.62
Chlorinated
SW
8.08
161
2.71
Chloraminated
SW
0.385
37.5
Chloraminated
SW
1.51
113
4.9
Chloraminated
SW
6.45
129
3.99
It
appeared
that
fronting
on
the
perchlorate
peak
in
the
drinking
the
water
matrices
was
contributing
to
the
peak
area,
which
would
account
for
the
unacceptable
high
recoveries
in
the
drinking
water
matrices
with
the
AS20
column.

10.
IMPROVING
METHOD
ROBUSTNESS
 
PHASE
2
Method
performance
outlined
in
Sections
8
and
9
above
indicated
that
the
method
was
still
not
sufficiently
robust
and
required
additional
optimization
10.1
EVALUATION
OF
RINSE
TIME
AND
LSSM
CONCENTRATION
The
reason
for
the
peak
fronting
and
high
recoveries
in
the
drinking
water
matrices
was
speculated
to
be
attributed
to
variable
retention
of
perchlorate
on
the
concentrator
column
in
the
different
strength
ionic
matrices.
It
was
decided
to
evaluate
a
12
and
15
minute
wash
time
in
varying
concentrations
of
the
LFSSM
containing
5.0
µ
g/
L
of
perchlorate
to
determine
if
the
perchlorate
behaved
differently
in
the
varying
ionic
strength
matrices.
As
shown
in
Figure
19,
the
rinse
time
had
essentially
no
affect
on
the
perchlorate
peak
area.
However,
a
dramatic
increase
in
peak
area
was
observed
between
the
50
and
100
TSC­
02­
0442
28
mg/
L
LFSSM
and
very
little
difference
in
the
perchlorate
peak
area
in
the
100
to
1000
mg/
L
LFSSM.
It
was
speculated
that
the
addition
of
50
mg/
L
of
the
LSSM
to
all
sample
matrices
was
responsible
for
a
low
perchlorate
response
in
the
RW
calibration
standards
which
contributed
to
the
high
recoveries
being
observed
in
the
normal
drinking
water
matrices.
It
was
thought
that
the
addition
of
100
mg/
L
to
all
sample
matrices
would
overcome
the
problem.

Figure
19.
12
vs.
15
Minute
Wash
Time
for
a
5.0

g/
L
ClO4
­
in
50
to
1000
mg/
L
LSSM
10.2
EVALUATION
OF
DRINKING
WATER
MATRICES
USING
100
mg/
L
LSSM
To
ensure
use
of
100
mg/
L
of
the
LSSM
would
resolve
the
high
drinking
water
recoveries,
the
calibration,
LCMRL
and
P&
A
data
in
the
chlorinated
and
chloraminated
surface
waters
were
repeated.
The
LCMRL
was
calculated
to
be
about
0.13
µ
g/
L
and
as
shown
in
Table
4,
much
better
recoveries
were
observed
in
the
drinking
chlorinated
and
chloraminated
water
matrices.
0.000
0.050
0.100
0.150
0
500
1000
mg/
L
LSSM
12
min
wash
15
min
wash
TSC­
02­
0442
29
TABLE
4.
Precision
and
Accuracy
for
EPA
Method
314.1
with
100
mg/
L
LFSSM
Native
Spike
Spike
Spike
%
%
Matrix
(
µ
g/
L)
0.5
µ
g/
L
1.0
µ
g/
L
5.0
µ
g/
L
REC
RSD
Chlorinated
SW
0.985
4.54
Chlorinated
SW
2.16
117
16.6
Chlorinated
SW
6.00
100
3.92
Chloraminated
SW
<
0.50
Chloraminated
SW
0.997
99.7
8.2
Chloraminated
SW
4.69
93.7
2.1
11.
FINAL
CONCENTRATOR
COLUMN
EVALUATION
The
finalized
protocols
included
one
further
modification
to
the
Cryptand
concentrator
column
resin
in
order
to
ensure
manufacturing
reproducibility.
Consequently,
the
final
concentrator
column
capacity
experiment
was
repeated
using
the
pre­
established
experimental
protocols.

11.1
FINAL
CONCENTRATOR
COLUMN
TRAPPING
EFFICIENCY
As
shown
in
Figure
20,
the
final
modification
to
the
concentrator
column
resin
resulted
in
a
moderately
lower
capacity
for
the
concentrator
column.
The
maximum
load
volume
that
could
be
used
and
still
meet
the
80%
restriction
was
now
2.0
mL.

Figure
20.
Concentrator
Column
Trapping
Efficiency
(
10

g/
L
ClO4
­
in
100
and
1000
mg/
L
LSSM
0.000
0.200
0.400
0.600
1
2
2.5
3
4
5
mL
LOADED
PEAK
AREA
(
uS
/
min)
100
mg/
L
LSSM
1000
mg/
L
LSSM
TSC­
02­
0442
30
12.
FINAL
METHOD
PROTOCOLS
FOR
EPA
METHOD
314.1
The
finalized
conditions
for
EPA
Method
314.1
are:
 
the
addition
of
100
mg/
L
LSSM
to
all
samples
 
2.0
mL
loading
volume
 
1.0
mL
of
10
mM
NaOH
rinse
solution
 
eluent
flow
rate
at
0.25
mL/
minute
 
operation
pressure
of
2350
psi
(
requirement
of
EG50)
 
0.50
mM
NaOH
to
wash
the
perchlorate
off
the
concentrator
column
and
refocus
it
at
the
head
of
the
AG16
column
 
65
mM
NaOH
to
separate
the
perchlorate
on
the
analytical
columns
 
100
mM
NaOH
immediately
after
the
elution
of
perchlorate
to
clean
and
prepare
the
columns
and
set
the
capacity
of
the
Cryptand
trap
column
for
the
next
analysis
 
AS16
as
the
primary
analytical
column
 
AS20
as
the
confirmation
analytical
column
13.
EPA
METHOD
314.1
EXPERIMENTAL
DATA
After
finalizing
the
experimental
protocols,
the
LCMRL
and
precision
and
accuracy
data
in
different
matrices
were
collected
for
both
the
primary
AS16
and
confirmation
AS20
analytical
columns.

13.1
PRIMARY
AS16
COLUMN
As
shown
in
Table
5,
acceptable
LCMRL
and
DL
data
was
obtained
on
the
primary
AS16
column.

TABLE
5.
LCMRL
Data
for
EPA
Method
314.1
with
"
Primary"
AS16
column
Analyte
LCMRL
a
(
µ
g/
L)
DL*
(
µ
g/
L)
ClO4
­
0.140
0.031b
aLCMRLs
were
calculated
according
to
the
procedure
in
reference
1
*
The
DL
was
calculated
from
data
acquired
on
a
single
day
bReplicate
fortifications
at
0.10
µ
g/
L
TSC­
02­
0442
31
As
shown
in
Table
6,
acceptable
precision
and
accuracy
data
was
obtained
on
the
primary
AS16
column.

TABLE
6.
Precision
and
Accuracy
Data
for
EPA
Method
314.1
with
"
Primary"
AS16
column
(
n=
7)

Matrix
Unfortified
Concentration
(
ug/
L)
Fortified
Concentration
(
ug/
L)
Mean
%
Recovery
%
RSD
100
mg/
L
LFSSM
*
<
MRL
0.50
102
2.6
<
MRL
5.0
90.0
3.2
Chlorinated
Surface
Water
0.63
1.0
82.6
1.5
0.63
5.0
85.8
1.7
Chloraminated
Surface
Water
<
MRL
1.0
83.1
3.6
<
MRL
5.0
89.3
1.9
Chlorinated
Ground
Water
<
MRL
1.0
75.9
5.4
<
MRL
5.0
92.4
3.3
100
mg/
L
LFSSM
*
<
MRL
0.50
102
2.8
<
MRL
5.0
80.9
1.3
*
LFSSM
=
Laboratory
Fortified
Synthetic
Sample
Matrix
13.2
CONFIRMATION
AS20
COLUMN
As
shown
in
Table
7,
acceptable
LCMRL
and
DL
data
was
obtained
on
the
confirmation
AS20
column.

TABLE
7.
LCMRL
Data
for
EPA
Method
314.1
with
confirmation
AS20
column
Analyte
LCMRL
a
(
µ
g/
L)
DL*
(
µ
g/
L)
ClO4
­
0.130
0.025b
aLCMRLs
were
calculated
according
to
the
procedure
in
reference
1
*
The
DL
was
calculated
from
data
acquired
on
a
single
day
bReplicate
fortifications
at
0.10
µ
g/
L
As
shown
in
Table
8,
acceptable
precision
and
accuracy
data
was
obtained
on
the
confirmation
AS20
column.
TSC­
02­
0442
32
TABLE
8.
Precision
and
Accuracy
Data
for
EPA
Method
314.1
with
primary
AS16
column
(
n=
7)

Matrix
Unfortified
Concentration
(
ug/
L)
Fortified
Concentration
(
ug/
L)
Mean
%
Recovery
%
RSD
100
mg/
L
LFSSM
*
<
MRL
0.50
104
5.3
<
MRL
5.0
94.2
1.5
Chloraminated
Surface
Water
<
MRL
0.50
108
2.2
<
MRL
5.0
97.8
2.0
Chlorinated
Ground
Water
0.22
0.50
96.2
9.4
0.22
5.0
98.0
0.70
100
mg/
L
LFSSM
*
<
MRL
0.50
97.4
4.4
<
MRL
5.0
86.3
1.3
*
LFSSM
=
Laboratory
Fortified
Synthetic
Sample
Matrix
14.
REFERENCES
1.
Personal
Communication.

2.
Revisions
to
the
Unregulated
Contaminant
Monitoring
Regulation
for
Public
Water
Systems,
Proposed
Rule,
2004.