Document ID: EPA-HQ-OW-2003-0002-0015
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2003-03-12T05:00Z

29
Method
Detection
Limit
Survey
Results
and
Analysis
Kerilynn
M.
Carden
Wisconsin
Department
of
Natural
Resources
Laboratory
Certification
Program
December
1998
PUBL­
SS­
930­
98
2
ABSTRACT
Since
1990,
the
Wisconsin
Department
of
Natural
Resources
(
DNR)
has
published
several
rules
requiring
laboratories
to
report
analytical
data
down
to
their
established
limits
of
detection
(
chapters
NR
149,
105
and
809,
Wis.
Adm.
Code).
The
DNR
is
concerned
about
data
at
these
low
levels
because
the
earliest
possible
detection
of
toxic
or
potentially
carcinogenic
chemicals
in
the
environment
is
paramount
in
the
DNR's
mission
to
protect
human
health,
wildlife,
fish,
and
the
environment.
Low
level
data
is
important
information
needed
by
agency
decision
makers.
In
cases
where
health­
based
standards
fall
below
typical
laboratory
detection
limits,
low
level
data
are
critical
for
making
the
correct
choices
when
designing
site
remediation
strategies,
alerting
the
public
to
health
threats,
and
protecting
wildlife
from
toxic
chemicals.

Data
users
that
know
how
to
properly
interpret
low
level
environmental
data
understand
analytical
variability
near
the
detection
limit.
This
variability
occurs
both
within
and
across
laboratories.
As
the
DNR
began
implementing
new
low
level
reporting
rules,
the
laboratory
certification
program
realized
the
need
to
determine
the
range
of
capabilities
across
Wisconsin
certified
and
registered
laboratories.
The
primary
purpose
of
the
spring
1998
survey
was
to
gather
information
on
the
range
and
variability
of
method
detection
limits
(
MDLs)
calculated
by
Wisconsin
certified
and
registered
laboratories
for
a
select
list
of
compounds
of
special
concern.
These
compounds
were
selected
based
upon
the
magnitude
of
their
health­
based
standards
and
the
DNR's
perception
of
analytical
capabilities
in
the
laboratory
industry.
The
report
includes
a
summary
of
the
statistics,
quartiles,
and
other
useful
information
about
MDLs
calculated
by
Wisconsin
certified
and
registered
laboratories.
3
DEFINITIONS
AND
ACRONYMS
Listed
below
are
definitions,
acronyms,
and
abbreviations
used
in
this
report.

Acute
Toxicity
Criteria
(
ATC):
This
is
the
maximum
daily
concentration
of
a
substance
which
ensures
adequate
protection
of
sensitive
species
of
aquatic
life
from
the
acute
toxicity
of
that
substance
and
will
adequately
protect
the
designated
fish
and
aquatic
life
use
of
the
surface
water
if
not
exceeded
more
than
once
every
3
years.
(
chapter
NR
105.03,
Wisconsin
Administrative
Code)

Cold
Vapor
Atomic
Absorption
(
CVAA):
This
is
a
technique
used
for
mercury
analysis.

Detection
Reporting
Requirement
List:
A
list
of
analytes
that
have
a
health
based
environmental
standard
in
chapters
NR
105,
140,
720,
and
809,
Wisconsin
Administrative
Code,
below
or
near
the
detection
limit.
Laboratories
are
required
to
report
all
data
for
these
substances
down
to
their
limit
of
detection.
(
Appendix
A)

Enforcement
Standard
(
ES):
This
is
a
numerical
value
expressing
the
maximum
allowable
concentration
of
a
substance
in
groundwater
which
is
adopted
under
s.
160.07,
Stats.,
and
s.
NR
140.10
or
s.
160.09,
Stats.,
and
s.
NR
140.12.
These
standards
are
toxicologically
derived
to
protect
human
health.
Analytical
values
above
the
ES
trigger
remediation
and
additional
monitoring.

Extraction/
Concentration
and
Atomic
Absorption
(
Extraction/
AA):
This
is
a
technique
occasionally
used
for
the
analysis
of
samples
with
very
low
metal
concentrations
(
most
commonly
hexavalent
chromium).

Flame
Atomic
Absorption
(
FLAA):
This
is
a
single
element
analysis
in
which
a
flame
is
used
to
dissociate
the
atoms
of
an
aspirated
sample
into
the
free
atomic
state,
rendering
them
available
for
the
absorption
of
light.

Gas
Chromatography
(
GC):
This
is
a
technique
used
for
the
separation
and
identification
of
organic
compounds.

Gas
Chromatography/
Mass
Spectrometry
(
GC/
MS):
This
is
a
specific
gas
chromatography
technique
that
uses
a
mass­
sensitive
detector
to
identify
the
compounds
of
interest.

Graphite
Furnace
Atomic
Absorption
(
GFAA):
This
is
similar
to
flame
atomic
absorption,
except
a
programmable
graphite
furnace
is
used
instead
of
a
flame.

High­
Performance
Liquid
Chromatography
(
HPLC):
This
is
a
technique
similar
to
gas
chromatography,
except
the
separation
of
individual
compounds
takes
place
in
the
liquid
phase
instead
of
the
gaseous
phase.
HPLC­
UV
is
the
technique
with
an
ultra
violet
detector
and
HPLCF
is
with
a
fluorescence
detector.
4
Human
Cancer
Criteria
(
HCC):
This
is
the
maximum
concentration
of
a
substance
or
mixture
of
substances
established
to
protect
humans
from
an
unreasonable
incremental
risk
of
cancer
resulting
from
contact
with
or
ingestion
of
surface
waters
of
the
state
and
from
ingestion
of
aquatic
organisms
taken
from
surface
waters
of
the
state.
(
chapter
NR
105.09,
Wisconsin
Administrative
Code)

Inductively
Coupled
Plasma
(
ICP):
A
multiple
element
analysis
technique
to
test
for
metals,
during
which
samples
are
aspirated
through
a
hot
plasma
torch.

Inductively
Coupled
Plasma/
Mass
Spectrometry
(
ICP/
MS):
This
technique
is
a
refinement
of
the
ICP
technique.
After
the
ions
are
generated
in
the
torch
plasma,
they
are
directed
to
a
mass
spectrometer.

Inductively
Coupled
Plasma­
Axial
Modified
Torch
(
ICP­
Trace):
This
technique
is
a
modification
of
the
conventional
ICP,
in
which
the
torch
is
mounted
horizontally
rather
than
vertically.
This
allows
the
sample
to
pass
through
the
plasma
torch
for
a
longer
period
of
time,
which
results
in
an
increase
in
emission
intensity
and
lower
detection
limits.

Limit
of
Detection
(
LOD):
This
is
the
lowest
concentration
level
that
can
be
determined
to
be
statistically
different
from
a
blank
(
99%
confidence).
The
LOD
is
typically
determined
to
be
in
the
region
where
the
signal
to
noise
ratio
is
greater
than
5.
Limits
of
detection
are
matrix,
method,
and
analyte
specific.
Unless
specified
differently,
it
is
assumed
that
the
numerical
value
of
the
LOD
is
the
same
as
the
MDL.

Limit
of
Quantitation
(
LOQ):
This
is
the
level
above
which
quantitative
results
may
be
obtained
with
a
specified
degree
of
confidence.
The
LOQ
is
mathematically
defined
as
equal
to
10
times
the
standard
deviation
of
the
results
for
a
series
of
replicates
used
to
determine
a
justifiable
limit
of
detection.
Limits
of
quantitation
are
matrix,
method,
and
analyte
specific.

Low­
Level
Mercury:
For
the
purposes
of
this
study,
low­
level
techniques
are
defined
as
technologies
that
provide
detection
capability
of
0.02
ug/
L
or
less
(
i.
e.
an
order
of
magnitude
below
generally
recognized
detection
capabilities).
Generally,
this
indicates
the
use
of
cold
vapor
atomic
fluorescence
technology.

Method
Detection
Limit
(
MDL):
This
the
minimum
concentration
of
a
substance
that
can
be
measured
and
reported
with
99%
confidence
that
the
analyte
concentration
is
greater
than
zero.
MDLs
are
matrix
specific,
and
must
be
calculated
according
to
the
procedure
outlined
in
Chapter
40,
Code
of
Federal
Regulations,
part
136,
Appendix
B,
rev.
1.11
(
Appendix
B).

Preventive
Action
Limit
(
PAL):
The
PAL
is
a
numerical
value
expressing
the
maximum
allowable
concentration
of
a
substance
in
groundwater
before
additional
monitoring
is
required.
PALs
are
adopted
under
s.
160.15,
Stats.,
and
s.
NR
140.10,
140.12
or
140.20.
The
PAL
is
typically
set
at
1/
10th
of
the
enforcement
standard
if
the
substance
is
carcinogenic,
mutagenic,
teratogenic
or
has
a
synergistic
effect.
The
PAL
is
20%
of
the
enforcement
standard
for
other
substances
of
public
health
concern.
(
NR
140.05(
17)
&
140.10
note)
5
Wildlife
Criteria
(
WC):
This
is
the
concentration
of
a
substance
which
if
not
exceeded
protects
Wisconsin's
wildlife
from
adverse
effects
resulting
from
ingestion
of
surface
waters
of
the
state
and
from
ingestion
of
aquatic
organisms
taken
from
surface
waters
of
the
state.
(
chapter
NR
105.07,
Wisconsin
Administrative
Code)
6
INTRODUCTION
The
Department
of
Natural
Resources
(
DNR)
requires
laboratories
to
report
monitoring
data
down
to
their
limit
of
detection
for
many
types
of
samples,
including
wastewater,
drinking
water
and
groundwater.
The
earliest
possible
detection
of
trace
chemicals
in
the
environment
is
paramount
to
the
protection
of
human
health
and
the
environment.
Regulators
base
environmental
policy
decisions
on
the
detection
of
toxic
chemicals
at
levels
that
are
perceived
to
have
environmental
consequences.
For
many
substances,
health­
based
environmental
standards
are
promulgated
without
regard
to
analytical
capabilities.
Where
health­
based
standards
fall
below
analytical
capabilities,
accurate
determinations
of
laboratory
detection
limits
are
important
for
interpreting
low­
level
data.
This
requires
that
data
users
understand
analytical
variability
near
the
detection
limit.
This
variability
occurs
both
within
and
across
laboratories.
When
a
laboratory
reports
a
value
as
"
less
than"
or
"
not
detected"
without
specifying
the
detection
limit,
interpretation
is
difficult.
To
assist
with
low­
level
data
interpretation,
regulators
require
laboratories
to
use
standardized
procedures
to
calculate
their
detection
limits.

The
Wisconsin
Department
of
Natural
Resources
requires
certified
and
registered
laboratories
to
calculate
detection
limits
using
the
U.
S.
Environmental
Protection
Agency
Method
Detection
Limit
(
MDL)
procedure
found
in
Title
40
Code
of
Federal
Regulations
Part
136
(
40
CFR
136,
Appendix
B,
revision
1.11).
Method
detection
limits
are
statistically
determined
values
that
define
how
easily
measurements
of
a
substance
by
a
specific
analytical
protocol
can
be
distinguished
from
measurements
of
a
blank
(
background
noise).
Method
detection
limits
are
matrix,
instrument
and
analyst
specific
and
require
a
well­
defined
analytical
method.
Variation
in
method
detection
limits
among
laboratories
is
attributable
to
differences
in
technique
and
instruments,
sample
contamination,
choice
of
method,
spike
level,
analytical
bias,
gross
error
(
systematic),
and
random
error
(
Draper
et.
al.,
1998).
Method
detection
limits
provide
a
useful
mechanism
for
comparing
different
laboratories'
capabilities
with
identical
methods
as
well
as
different
analytical
methods
within
the
same
laboratory.
The
MDL
procedure
is
simple,
and
has
wide
applicability
in
environmental
monitoring.
The
Wisconsin
laboratory
certification
and
registration
program
has
developed
guidance
to
assist
laboratories
and
generate
meaningful
detection
limits
(
WDNR,
1996).

In
support
of
the
Department's
efforts
to
quantify
and
interpret
low
level
data,
the
laboratory
certification
and
registration
program
designed
a
survey
to
compile
information
about
detection
limit
capabilities
across
Wisconsin
certified
and
registered
laboratories.
The
primary
purpose
of
this
survey
was
to
gather
information
on
the
range
and
variability
of
MDLs
calculated
for
a
select
list
of
compounds
of
special
concern.
These
compounds
were
chosen
because
their
health­
based
standards
are
similar
in
magnitude
to
detection
limits
achievable
in
the
environmental
laboratory
industry.

The
DNR
had
the
following
objectives
for
the
limit
of
detection
survey:

1.
Determine
the
percentage
of
laboratories
that
correctly
calculate
MDLs
and
identify
the
most
common
errors
laboratories
make
when
calculating
MDLs.
7
2.
Gather
information
on
the
range
and
variability
of
reagent
water
MDLs
reported
by
laboratories
for
selected
analytes
on
the
Detection
Reporting
Requirement
list
(
included
as
Appendix
A).
3.
Compare
calculated
MDLs
with
reported
detection
limits
to
discover
the
level
of
detection
that
is
routinely
achievable
for
the
compounds
on
the
Detection
Reporting
Requirement
list.

This
report
fulfills
the
first
two
objectives;
summarizing
the
calculated
method
detection
limits
and
investigating
problems
with
the
MDL
determinations.
The
information
presented
in
this
report
is
useful
for
comparing
MDLs
across
laboratories,
but
does
not
investigate
specific
situations
where
the
calculated
MDL
is
not
analytically
feasible.
Calculated
MDLs
may
not
reflect
real­
world
detection
limits
for
several
reasons
(
WDNR,
1996).
Most
importantly,
calculated
MDLs
are
often
determined
using
reagent
water
spiked
with
the
analyte
of
interest,
rather
than
a
specific
matrix
such
as
wastewater
or
soils
using
the
same
procedure.
Reagent
water
MDLs
can
be
described
as
"
best
case
limits",
and
the
detection
limits
achievable
in
clean
samples
may
not
be
analytically
achievable
in
other
matrices.
Nonetheless,
calculating
the
MDL
in
reagent
water
is
useful
for
comparing
detection
limits
among
many
laboratories.
The
Department
intends
to
investigate
the
detection
limit
data
in
more
detail
and
hopes
to
release
future
reports
that
will
focus
specifically
on
how
calculated
MDLs
compare
to
routinely
achievable
detection
limits
in
real
world
samples.
8
MATERIALS
AND
METHODS
The
DNR
began
this
detection
limit
investigation
in
January,
1998.
First,
the
DNR
designed
and
mailed
a
survey
to
laboratories
certified
or
registered
for
the
compounds
on
the
Detection
Reporting
Requirement
list
(
Appendix
A).
The
survey
requested
information
about
how
laboratories
calculated
MDLs,
LODs,
and
limits
of
quantitation
(
LOQs).
After
all
of
the
laboratories
had
responded,
the
DNR
compiled
the
data
into
a
database
and
the
results
were
validated
based
upon
the
requirements
of
the
MDL
procedure
in
40
CFR
136
(
Appendix
B).
Method
detection
limits
that
did
not
meet
the
necessary
criteria
were
removed
from
the
data
set.
Finally,
the
Department
conducted
a
statistical
analysis
(
e.
g.
range,
mean,
median,
and
quartiles)
of
the
valid
data.

Survey
Development
The
analytes
chosen
for
this
survey
can
be
found
on
the
Detection
Reporting
Requirement
list
(
Appendix
A).
This
list
of
analytes
includes
all
primary
drinking
water
contaminants
specified
in
chapter
NR
809,
Wis.
Adm.
Code,
and
those
substances
specified
in
chapters
NR
105,
140
and
720,
Wis.
Adm.
Code,
that
have
health­
based
environmental
standards
below
or
near
the
detection
limit.
All
certified
or
registered
laboratories
analyzing
for
these
substances
were
required
to
submit
their
MDL,
LOD,
and
LOQ
information
to
the
Department
to
comply
with
Wisconsin
regulations.
Specifically,
the
survey
requested
that
the
laboratories
submit
instrument
type,
methods
used,
spike
concentrations,
replicate
results,
and
the
mean
and
standard
deviation
of
the
replicates.
The
laboratories
had
the
option
of
submitting
their
detection
limit
data
electronically
or
by
mail
to
the
Department.
A
copy
of
the
request
letter
and
the
spreadsheet
can
be
found
in
Appendix
C.

Database
Construction
The
Department
entered
the
information
into
a
database
as
it
was
received
from
the
laboratories.
The
data
were
checked
for
consistency.
All
results
were
to
be
reported
in
micrograms
per
liter
(
m
g/
L).
If
other
units
were
reported
the
data
were
adjusted
to
make
the
units
consistent.
The
method
numbers
had
to
be
consistent
with
the
instrument
used.
Once
all
of
the
data
was
standardized
(
e.
g.
units,
spelling,
methods),
each
submittal
was
reviewed
to
determine
if
it
met
the
necessary
criteria
and
could
be
used
in
the
analysis.

Data
Validation
The
Department
validated
the
data
using
the
following
criteria:

1.
Incomplete
Data
Set
 
A
laboratory
was
contacted
if
it
did
not
submitted
all
of
the
information
requested
or
if
there
were
inconsistencies
with
their
data.
If
the
laboratory
could
not
supply
the
necessary
information,
the
data
were
not
used
in
this
report.
2.
Not
a
Water
Matrix
 
The
DNR
requested
that
laboratories
report
all
detection
limit
data
based
on
a
reagent
water
matrix.
If
an
alternative
matrix
(
e.
g.
soil,
oil,
sediment)
was
used,
that
specific
data
point
was
removed
from
this
report.
9
3.
Less
Than
7
Replicates
 
According
to
the
EPA's
procedure
for
calculating
the
MDL,
at
least
seven
replicates
have
to
be
used
to
calculate
the
MDL.
MDL
determinations
that
did
not
use
a
minimum
of
seven
replicates
were
excluded.
4.
Spike
Too
High/
Low
 
The
EPA's
MDL
procedure
has
specific
spiking
criteria,
requiring
that
laboratories
spike
at
concentrations
less
than
ten
times
the
calculated
MDL.
Spiked
concentrations
should
also
be
greater
than
the
calculated
MDL.
The
spike
level
specifications
are
important
to
minimize
variability
between
laboratories.
Data
that
did
not
meet
the
spiking
criteria
were
excluded.
5.
Miscalculated
MDL
 
The
data
set
was
checked
to
determine
if
the
MDLs
were
calculated
correctly.
To
allow
for
rounding,
a
ten
percent
margin
was
used
when
checking
for
miscalculated
MDLs.
Miscalculated
MDLs
were
not
used
in
the
analysis.

Twenty­
six
percent
(
26%)
of
the
submitted
results
were
not
used
because
they
failed
to
meet
all
of
the
criteria
listed
above.
Figure
1
presents
a
summary
of
the
discarded
data.

Figure
1:
Breakdown
of
Discarded
Data.

4%
A
and
B
13%

B
38%
A
42%
1%
2%
42%
A
­­
Spiked
Too
High/
Low
38%
B
­­
Miscalculated
MDL
13%
Both
A
and
B
4%
Incomplete
Data
Set
2%
Not
Water
Matrix
1%
Less
Than
7
Replicates
Of
the
122
laboratories
that
submitted
MDL
data,
it
is
noteworthy
that
only
17%
of
the
laboratories
returned
data
that
met
the
criteria
for
each
analyte.
Of
the
remaining
83%,
71%
returned
surveys
that
met
the
criteria
for
some
analytes,
but
not
others
while
12%
of
the
surveys
had
to
be
discarded
completely
(
Figure
2).
10
Figure
2:
Percent
of
Laboratories
Submitting
Usable
Data
Sets
All
Usable
17%

Invalid
12%
Some
Usable
71%

Statistical
Analysis
Statistical
analyses
were
conducted
on
the
remaining
data
set
to
determine
the
percentage
of
reported
results
that
were
at
or
below
the
PAL.
Quartiles
of
the
MDL
data
(
25%,
50%,
75%,
and
100%)
were
constructed.
The
MDL
ranges,
means,
and
medians
for
each
analyte
by
instrument
type
were
also
determined.
The
following
results,
discussion,
and
conclusions
are
based
on
a
data
set
of
over
2,313
MDL
results.
11
RESULTS
AND
DISCUSSION
The
calculated
MDLs
were
compared
to
groundwater
standards
(
PALs)
and
surface
water
quality
standards
to
determine
if
current
technology
is
capable
of
detecting
these
analytes
at
these
levels.
It
is
important
to
note
that
the
wildlife
criteria
(
WC)
are
implemented
to
protect
the
health
of
wildlife.
The
25%
quartile
demonstrates
the
detection
limits
that
25%
of
the
laboratories
could
be
expected
to
achieve,
the
median
(
50%
quartile)
represents
the
detection
limit
achievable
by
50%
of
the
laboratories,
and
so
forth.
The
one­
hundredth
percentile,
or
forth
quartile,
is
equal
to
the
highest
MDL
reported
for
a
given
analyte.
All
laboratories
participating
in
the
survey
are
capable
of
detecting
the
analyte
at
this
level.
The
quartile
representation
is
also
a
way
to
estimate
what
MDLs
a
laboratory
can
be
expected
to
achieve
for
specific
analytes.
The
ranges,
means,
and
medians
for
each
analyte
of
interest
were
calculated
to
help
determine
if
a
particular
analytical
method
consistently
produced
lower
MDLs.
The
following
discussion
is
divided
into
six
sections:
metals,
volatile
organic
compounds
(
VOCs),
semivolatile
organic
compounds,
pesticides,
PAHs,
and
PCBs.

Metals
Although
several
metals
are
listed
on
the
Detection
Reporting
Requirement
list
(
Appendix
A),
only
the
MDLs
submitted
for
cadmium
(
Cd),
hexavalent
chromium
(
Cr+
6),
lead
(
Pb),
mercury
(
Hg),
and
thallium
(
Tl)
were
analyzed
in
this
report.
These
metals
are
introduced
into
the
environment
as
byproducts
of
industrial
processes
such
as
metal
plating
and
machining
or
in
municipal
wastewater
effluents.

The
DNR
was
interested
in
determining
if
current
analytical
technologies
are
capable
of
detecting
metals
at
the
PAL.
The
MDLs
for
cadmium,
lead,
thallium,
and
mercury
were
compared
to
the
PALs
(
Figure
3).
A
laboratory
using
a
graphite
furnace
atomic
absorption
(
GFAA)
or
inductively
coupled
plasma/
mass
spectrometry
(
ICP/
MS)
instrument
should
be
able
to
consistently
achieve
a
MDL
at
or
below
the
PAL.
On
the
contrary,
laboratories
that
use
flame
atomic
absorption
(
FLAA)
or
inductively
coupled
plasma
(
ICP)
instruments
are
not
likely
to
be
able
to
detect
these
metals
at
levels
at
or
below
the
PAL.
It
is
noteworthy
that
at
this
time
the
PAL
for
thallium
is
beyond
the
reach
of
current
technology.
All
of
the
methods
used
to
test
for
mercury
can
consistently
detect
it
at
or
below
the
PAL.
12
Figure
3:
Percent
of
Metal
MDLs
that
Met
the
PAL
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%

Instrument
Cadmium
(
PAL
=
0.5
ug/
L)

Lead
(
PAL
=
1.5
ug/
L)

Thallium
(
PAL
=
0.4
ug/
L)

Mercury
(
PAL
=
0.2
ug/
L)

Table
1
is
a
summary
of
the
MDL
quartiles
for
metals.
Each
metal
is
divided
by
instrument
or
detector
type.
It
is
important
to
note
that
the
information
for
thallium
by
FLAA
and
mercury
by
ICP/
MS
is
limited
because
very
few
values
were
reported.

Table
1:
MDL
Quartiles
for
Metals
25%
50%
75%
100%
Cadmium
(
Cd)
0.118
0.353
2.5
19
FLAA
3.17
4.83
8.9
19
GFAA
0.0815
0.116
0.19
0.51
ICP
1.47
2.5
3.58
9.6
ICP/
MS
0.037
0.061
0.101
0.2
ICP­
Trace
0.257
0.386
0.603
2.9
Chromium,
Hexavalent
(
Cr+
6)
1.51
2.88
6.53
126
Extraction/
AA
1.3
2.6
5.6
8.3
Colorimetric
1.89
3.19
6.68
126
Lead
(
Pb)
0.85
1.39
16.5
100
FLAA
27.5
37.7
61.8
100
GFAA
0.696
0.9
1.355
3.3
ICP
17.5
28.7
37.4
86.7
ICP/
MS
0.078
0.096
0.155
0.621
ICP­
Trace
1.285
1.55
2.1
16.7
Mercury
(
Hg)
0.033
0.0705
0.11
0.6
Cold
Vapor
AA
0.0515
0.076
0.12
0.6
Low
Level
0.0029
0.0062
0.0088
0.161
ICP/
MS
NA
NA
NA
0.02
Thallium
(
Tl)
0.8635
2.06
5.3
327.0
FLAA
NA
NA
NA
60.0
GFAA
0.715
1.0
1.405
5.0
ICP
22.35
50.0
84.7
327.0
ICP/
MS
0.015
0.04
0.0506
0.51
ICP­
Trace
2.76
3.83
5.0
9.7
*
All
units
are
in
m
g/
L
13
Each
metal
is
discussed
individually
below.
The
information
includes
a
table
containing
a
summary
of
the
ranges,
mean,
and
medians.

Cadmium
(
Cd)

When
very
low
detection
limits
are
necessary,
conventional
ICP
and
FLAA
are
not
generally
capable
of
producing
detection
limits
comparable
to
newer
technology.
The
Inductively
Coupled
Plasma­
Axial
Modified
Torch
(
ICP­
Trace)
instruments
are
becoming
more
widely
used,
and
with
some
refinements
may
eventually
be
able
to
achieve
MDLs
closer
to
those
calculated
using
GFAA
and
ICP/
MS
techniques.
It
is
interesting
to
note
that
GFAA
and
ICP
had
almost
the
same
number
of
results,
yet
the
median
ICP
MDL
was
more
than
one
order
of
magnitude
greater
than
the
GFAA
MDLs.

Cadmium
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
152
19
0.005
1.72
0.353
0.5
FLAA
14
19
1.9
7.45
4.83
GFAA
56
0.51
0.02
0.15
0.12
ICP
46
9.6
0.024
2.84
2.5
ICP/
MS
8
0.2
0.005
0.07
0.06
ICP­
Trace
28
2.9
0.16
0.6
0.39
*
All
units
are
in
m
g/
L
Lead
(
Pb)

The
MDL
results
from
FLAA
and
ICP
instruments
are
significantly
higher
than
the
alternative
methods.
As
more
laboratories
use
the
ICP­
Trace
technologies,
consistently
lower
MDLs
and
results
at
or
below
the
PAL
may
be
increasingly
obtainable.

Lead
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
170
100
0.005
11.35
1.4
1.5
FLAA
14
100
9.6
44.14
37.69
GFAA
78
3.3
0.23
1.09
0.9
ICP
37
86.7
0.121
30.87
28.7
ICP/
MS
7
0.62
0.005
0.17
0.096
ICP­
Trace
34
16.7
0.58
2.45
1.55
*
All
units
are
in
m
g/
L
Thallium
(
Tl)

The
data
show
that
the
majority
of
the
instruments
currently
used
to
test
for
thallium
are
not
sufficiently
sensitive
to
meet
groundwater
criteria.
ICP/
MS
appears
to
be
the
most
promising
technology
available
for
low
level
detection
of
thallium.

Thallium
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
87
327
0.004
16.7
2.1
0.4
FLAA
3
60
26
48.67
60
GFAA
43
5
0.2
1.26
1
14
Thallium
#
of
Results
Maximum
Minimum
Mean
Median
PAL
ICP
15
327
5.9
77.92
50
ICP/
MS
5
0.509
0.004
0.12
0.04
ICP­
Trace
21
9.7
2
4.17
3.83
*
All
units
are
in
m
g/
L
Hexavalent
Chromium
(
Cr6+)

Hexavalent
chromium
does
not
have
a
PAL
associated
with
it.
However,
an
water
quality
standard
for
hexavalent
chromium
is
the
acute
toxicity
criteria
(
ATC)
found
in
chapter
NR
105.
The
ATC
for
all
aquatic
life
for
this
compound
is
16.02
m
g/
L.
Only
one
result
was
above
this
level.
Although
the
Extraction/
Concentration
and
Atomic
Absorption
(
Extraction/
AA)
method
is
capable
of
detecting
hexavalent
chromium
at
slightly
lower
levels,
it
is
not
often
used
by
environmental
laboratories.
The
Extraction/
AA
method
is
more
expensive
and
time
consuming
than
colorimetric
procedures.

Hexavalent
Chromium
(
Cr6+)
#
of
Results
Maximum
Minimum
Mean
Median
PAL
ATC
Total
26
126
0.58
8.78
2.88
NA
16.02
Extraction/
AA
5
8.3
0.58
3.68
2.6
Colorimetric
20
126
0.6
10.44
3.19
ICP­
Trace
1
­­­
­­­
­­­
0.91
*
All
units
are
in
m
g/
L
Mercury
(
Hg)

Cold
Vapor
Atomic
Absorption
(
CVAA)
has
the
ability
to
detect
mercury
at
or
below
the
PAL.
However,
this
type
of
analysis
is
more
prone
to
false
positives
caused
by
contamination
in
sampling
and
analytical
procedures
because
there
is
ambient
mercury
in
the
laboratory.
In
January
1996
a
low
level
method
for
mercury
analysis
was
approved
by
EPA.
The
low
level
method
compresses
the
sample
to
get
a
stronger
signal
for
mercury.
Since
the
PAL
is
not
the
lowest
water
quality
standard,
the
results
for
mercury
were
also
compared
to
the
wildlife
criteria
(
WC)
value
found
in
chapter
NR
105.
The
WC
for
mercury
is
0.0013
m
g/
L.
Only
two
of
the
reported
results
were
below
this
level.
The
technologies
being
used
to
detect
mercury
at
low
levels
are
improving
due
to
increased
awareness
and
initiatives
to
reduce
sources
of
mercury
contamination
in
the
laboratory.

Mercury
#
of
Results
Maximum
Minimum
Mean
Median
PAL
WC
Total
74
0.6
0.00014
0.085
0.071
0.2
0.0013
CVAA
65
0.6
0.0054
0.0955
0.076
Low
Level
7
0.0161
0.00014
0.0065
0.0062
ICP/
MS
2
0.02
0.0129
0.016
­­­
*
All
units
are
in
m
g/
L
unless
otherwise
specified.
15
Summary
of
Metal
Results
There
are
numerous
methods
currently
available
to
test
for
metals
in
water.
For
cadmium,
lead,
and
thallium,
ICP/
MS
consistently
produced
the
lowest
MDL
results.
The
second
lowest
MDL
results
for
these
metals
came
from
GFAA
instruments.
The
more
recent
ICP­
Trace
instruments
are
capable
of
producing
low
MDLs,
but
still
cannot
detect
metals
at
the
same
levels
as
GFAA
and
ICP/
MS.
As
more
laboratories
use
the
ICP­
Trace
technology,
consistently
lower
MDLs
and
results
at
or
below
the
PAL
may
be
increasingly
obtainable.
Using
FLAA
or
ICP
to
test
for
cadmium,
lead,
and
thallium
resulted
in
an
average
MDL
10
to
100
times
greater
than
the
other
methods.
The
MDL
results
for
mercury
demonstrate
that
the
current
technologies
allow
laboratories
to
consistently
meet
the
PAL.
The
colorimetric
method
does
not
produce
the
lowest
MDLs,
but
remains
the
most
common
procedure
for
determining
hexavalent
chromium.

Volatile
Organic
Compounds
(
VOCs)

Nine
of
the
thirteen
volatile
compounds
on
the
Detection
Reporting
Requirement
list
(
Appendix
A)
were
analyzed
in
this
report.
Volatile
organic
compounds
(
VOCs)
are
introduced
into
the
environment
from
a
variety
of
sources,
including
spent
solvents,
leaky
storage
tanks,
and
landfills.

All
of
the
MDLs
for
VOCs
were
evaluated
in
relation
to
the
PALs.
Figure
4
summarizes
the
percentage
of
MDLs
that
met
the
PAL.
In
all
cases,
a
slightly
higher
percentage
of
MDLs
obtained
by
GC
were
able
to
meet
the
PAL
than
MDLs
obtained
by
GC/
MS.
For
five
of
the
nine
compounds,
at
least
60%
of
the
total
reported
MDLs
were
at
or
below
the
PAL.
In
the
instances
where
the
PAL
was
not
met
or
only
met
by
a
few
laboratories,
the
PALs
are
extremely
low.
Current
technology
may
not
be
sufficiently
sensitive
to
consistently
detect
those
analytes
at
or
below
the
PAL.
16
Figure
4:
Percent
of
VOC
MDL
Results
that
Meet
the
PAL
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%

Chemical
Compound
All
GC
GC/
MS
Table
2
summarizes
the
results
of
the
laboratories'
capabilities
for
detecting
VOCs.
As
with
metals,
each
analyte
has
been
subdivided
by
instrument
type.
For
the
majority
of
the
VOCs
the
MDL
values
at
the
first
and
second
quartiles
(
25%
and
50%,
respectively)
are
relatively
similar.
At
the
third
quartile
(
75%)
a
larger
difference
between
GC
and
GC/
MS
can
be
seen.
In
this
case
all
of
the
third
quartile
results
are
greater
than
the
GC
MDL
results.
The
fourth
quartile
(
100%)
values
for
GC
and
GC/
MS
lack
a
definite
pattern,
possibly
due
to
outliers
at
the
upper
end
of
the
scale.

Table
2:
MDL
Quartiles
for
VOCs
25%
50%
75%
100%
1,1,2,2­
Tetrachloroethane
0.1305
0.24
0.465
2.51
GC
0.13
0.233
0.3
2.51
GC/
MS
0.132
0.245
0.57
2.27
1,1,2­
Trichloroethane
0.15
0.227
0.364
7.2
GC
0.15
0.196
0.3
2.14
GC/
MS
0.15
0.23
0.41
7.2
1,3­
Dichloropropene
(
cis
&
trans)
0.12
0.25
0.43
2.18
GC
0.103
0.22
0.37
0.581
GC/
MS
0.12
0.286
0.47
2.18
cis­
1,3­
Dichloropropene
0.107
0.175
0.273
1.89
GC
0.123
0.212
0.256
1.89
GC/
MS
0.106
0.155
0.389
1.374
17
25%
50%
75%
100%
trans­
1,3­
Dichloropropene
0.13
0.189
0.46
6.29
GC
0.122
0.2
0.243
2.12
GC/
MS
0.133
0.184
0.574
6.29
Bromomethane
0.17
0.32
0.75
5.84
GC
0.2
0.336
0.611
3.6
GC/
MS
0.17
0.317
0.83
5.84
Chloroform
0.117
0.2
0.391
6.12
GC
0.128
0.213
0.337
1.89
GC/
MS
0.109
0.198
0.503
6.12
Chloromethane
0.16
0.317
0.635
6.61
GC
0.172
0.34
0.59
5.88
GC/
MS
0.16
0.31
0.65
6.61
Methylene
Chloride
0.2
0.36
0.678
5.87
GC
0.225
0.302
0.55
2.54
GC/
MS
0.15
0.42
0.84
5.87
Methyl
tert­
butyl
ether
(
MTBE)
0.159
0.299
0.6
6.7
GC
0.17
0.292
0.445
6.7
GC/
MS
0.13
0.32
0.78
2.58
Vinyl
Chloride
0.15
0.25
0.5
5.81
GC
0.147
0.25
0.45
2.22
GC/
MS
0.15
0.233
0.58
5.81
*
All
units
are
in
m
g/
L
The
following
information
contains
a
statistical
analysis
for
each
VOC
analyzed
in
this
report.
The
information
includes
a
table
containing
a
summary
of
the
ranges,
mean,
and
medians
for
each
volatile.

1,1,2,2­
Tetrachloroethane
GC
and
GC/
MS
instruments
obtained
similar
ranges,
means,
and
medians
demonstrating
that
the
two
methods
are
not
significantly
different
for
this
compound.

1,1,2,2­
Tetrachloroethane
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
103
2.51
0.013
0.385
0.24
0.02
GC
37
2.51
0.013
0.318
0.233
GC/
MS
66
2.27
0.027
0.422
0.245
*
All
units
are
in
m
g/
L
1,1,2­
Trichloroethane
The
data
indicate
that
GC
is
slightly
more
sensitive
than
GC/
MS
for
analyzing
1,1,2­
Trichloroethane.

1,1,2­
Trichloroethane
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
115
7.2
0.015
0.37
0.227
0.5
GC
42
2.14
0.015
0.28
0.196
GC/
MS
73
7.2
0.044
0.43
0.23
*
All
units
are
in
m
g/
L
18
1,3­
Dichloropropene
The
median
for
each
isomer,
by
each
method,
was
about
one
order
of
magnitude
greater
than
the
PAL.
With
current
technology
it
is
not
realistic
for
a
laboratory
to
detect
1,3­
dichloropropene
at
0.02
m
g/
L.
GC
and
GC/
MS
MDL
results
are
comparable.

1,3­
Dichloropropene
#
of
Results
Maximum
Minimum
Mean
Median
PAL
1,3­
Dichloropropene
(
cis
&
trans)
58
2.18
0.05
0.36
0.25
0.02
GC
21
0.58
0.054
0.25
0.22
GC/
MS
37
2.18
0.05
0.43
0.286
cis­
1,3­
Dichloropropene
40
1.89
0.019
0.301
0.175
0.02
GC
14
1.89
0.019
0.31
0.212
GC/
MS
26
1.37
0.031
0.3
0.155
trans­
1,3­
Dichloropropene
41
6.29
0.016
0.49
0.19
0.02
GC
15
2.12
0.016
0.34
0.2
GC/
MS
26
6.29
0.049
0.59
0.184
*
All
units
are
in
m
g/
L
Bromomethane
The
ranges,
means,
and
medians
between
GC
and
GC/
MS
demonstrate
little
variability
between
the
two
instrument
types.
Due
to
the
fact
that
bromomethane
is
a
gas
and
volatilizes
readily,
the
reported
MDLs
are
higher.
Nonetheless,
current
methods
and
instruments
used
for
detecting
bromomethane
are
capable
of
quantifying
this
compound
at
or
below
the
PAL.

Bromomethane
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
105
5.84
0.052
0.62
0.32
1.0
GC
36
3.6
0.052
0.55
0.336
GC/
MS
69
5.84
0.06
0.658
0.317
*
All
units
are
in
m
g/
L
Chloroform
As
seen
for
many
of
the
volatile
organic
compounds,
the
MDL
range
from
GC/
MS
instruments
is
much
greater
than
that
of
GC.
The
medians
for
the
two
methods
are
very
similar.
Again,
the
current
methods
are
able
to
detect
chloroform
at
low
levels.

Chloroform
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
115
6.12
0.017
0.374
0.2
0.6
GC
43
1.89
0.017
0.284
0.213
GC/
MS
72
6.12
0.038
0.428
0.198
*
All
units
are
in
m
g/
L
19
Chloromethane
Detection
of
chloromethane
in
environmental
samples
is
hampered
because
it
is
a
gas
that
readily
volatilizes
at
room
temperature,
which
increases
the
MDL.
The
ranges,
means,
and
medians
for
the
two
methods
were
very
similar
showing
that
the
two
instruments
are
comparable.
The
current
technologies
available
for
analyzing
chloroform
produce
similar
results,
but
refinements
are
necessary
if
lower
detection
levels
are
required.

Chloromethane
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
110
6.6
0.051
0.66
0.32
0.3
GC
37
5.88
0.051
0.68
0.34
GC/
MS
73
6.61
0.053
0.66
0.31
*
All
units
are
in
m
g/
L
Methylene
Chloride
The
range
for
GC/
MS
is
wider
than
that
of
other
GC
instruments;
therefore,
more
consistent
MDL
results
are
seen
with
GC
instruments.
Methylene
chloride
is
a
common
laboratory
solvent,
and
poor
laboratory
ventilation
increases
analytical
variability
and
detection
limits.

Methylene
Chloride
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
100
5.87
0.026
0.678
0.36
0.5
GC
36
2.54
0.026
0.487
0.3015
GC/
MS
64
5.87
0.031
0.786
0.408
*
All
units
are
in
m
g/
L
Methyl
tert­
butyl
ether
(
MTBE)

GC/
MS
detection
allows
for
greater
sensitivity
because
MTBE
tends
to
coelute
with
the
solvent
front
in
GC
determinations.
The
coelution
diminishes
sensitivity
of
the
photoionization
detector
(
PID)
used
with
GC.
As
a
result,
the
GC/
MS
MDL
range
was
smaller
than
that
found
with
GC
instrumentation.

MTBE
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
113
6.7
0.029
0.55
0.3
12.0
GC
66
6.7
0.041
0.6
0.292
GC/
MS
47
2.58
0.029
0.48
0.32
*
All
units
are
in
m
g/
L
Vinyl
Chloride
The
wide
range
in
the
GC/
MS
MDL
data
shows
that
there
is
greater
variability
when
analyzing
vinyl
chloride
by
GC/
MS
compared
to
GC.

Vinyl
Chloride
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
131
5.81
0.0049
0.47
0.25
0.02
GC
45
2.22
0.013
0.354
0.25
20
Vinyl
Chloride
#
of
Results
Maximum
Minimum
Mean
Median
PAL
GC/
MS
86
5.81
0.0049
0.535
0.23
*
All
units
are
in
m
g/
L
Summary
of
VOC
Results
Overall,
about
half
of
the
PALs
for
the
volatile
compounds
analyzed
here
were
achievable
using
available
technologies.
It
is
important
to
note
that
almost
twice
the
number
of
laboratories
are
using
GC/
MS
as
GC
to
analyze
volatile
samples.
A
smaller
range
was
seen
with
the
GC
instruments
which
may
be
attributed
to
the
smaller
sample
size
or
that
the
GC
instruments
are
more
sensitive
than
GC/
MS.
According
to
the
Student's
t­
test
statistical
analysis,
the
reported
MDLs
for
GC
and
GC/
MS
are
not
significantly
different
for
any
of
the
volatile
analytes
discussed
above.

Semivolatile
Organic
Compounds
Four
semivolatile
organic
compounds
were
analyzed:
2,4­
dinitrotoluene,
2,6­
dinitrotoluene,
di(
2­
ethylhexyl)
phthalate,
and
pentachlorophenol.
Ninety­
five
percent
(
95%)
of
the
MDLs
were
generated
with
GC/
MS
with
the
remaining
5%
by
GC.
The
PALs
for
these
compounds
were
significantly
lower
than
the
capability
of
the
laboratories
surveyed.

The
results
for
semivolatile
organic
compounds
are
summarized
in
Table
3.
Each
analyte
is
subdivided
by
instrument
type,
where
applicable.

Table
3:
MDL
Quartiles
for
Semivolatile
Organic
Compounds
25%
50%
75%
100%
2,4­
Dinitrotoluene
0.69
1.2
2.0
5.9
GC/
MS
0.84
1.25
2.03
5.9
2,6­
Dinitrotoluene
0.605
1.4
2.46
6.32
GC/
MS
0.75
1.42
2.6
6.32
Di(
2­
ethylhexyl)
phthalate
1.18
1.9
2.7
16.7
GC/
MS
1.15
2.0
2.71
16.7
Pentachlorophenol
0.823
2.02
3.63
17.9
GC/
MS
1.02
2.2
3.9
17.9
GC
0.058
0.68
2.82
3.33
*
All
units
are
in
m
g/
L
Below
is
a
statistical
analysis
for
each
semivolatile
organic
compound
analyzed
in
this
report.
The
information
includes
a
summary
of
the
ranges,
mean,
and
medians
for
each
analyte
and
method.

2,4­
Dinitrotoluene
The
data
indicate
that
the
available
technologies
are
not
sufficiently
sensitive
to
detect
2,4­
dinitrotoluene
at
or
near
the
PAL
(
0.005).
The
GC
MDLs
are
much
lower
than
the
GC/
MS
MDLs,
but
a
larger
sample
size
is
necessary
to
draw
more
definitive
conclusions.

2,4­
Dinitrotoluene
#
of
Results
Maximum
Minimum
Mean
Median
PAL
21
2,4­
Dinitrotoluene
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
42
5.9
0.0163
1.67
1.2
0.005
GC/
MS
40
5.9
0.11
1.76
1.25
GC
2
0.0274
0.0163
0.022
NA
*
All
units
are
in
m
g/
L
2,6­
Dinitrotoluene
As
with
2,4­
dinitrotoluene,
technology
for
detecting
2,6­
dinitrotoluene
is
not
sensitive
enough
to
detect
at
or
near
the
PAL.

2,6­
Dinitrotoluene
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
39
6.32
0.0214
1.7
1.4
0.005
GC/
MS
37
6.32
0.11
1.79
1.42
GC
2
0.0266
0.0214
0.024
NA
*
All
units
are
in
m
g/
L
Di(
2­
ethylhexyl)
phthalate
The
range
of
the
MDLs
for
di(
2­
ethylhexyl)
phthalate
is
wide;
extending
from
0.61
to
16.7
m
g/
L.
The
wide
range
can
be
attributed
to
the
fact
that
this
is
a
common
laboratory
contaminant
and
will
interfere
in
the
analysis.
As
seen
with
the
previous
two
semivolatile
organic
compounds,
the
GC/
MS
methods
being
used
today
are
not
capable
of
detecting
this
compound
at
the
PAL.

Di(
2­
ethylhexyl)
phthalate
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
44
16.7
0.61
2.36
1.9
0.5
GC/
MS
42
16.7
0.61
2.42
2.0
GC
2
1.27
1.19
1.23
NA
*
All
units
are
in
m
g/
L
Pentachlorophenol
As
with
all
of
the
other
semivolatile
organic
compounds,
the
PAL
is
not
routinely
achievable
using
current
GC/
MS
instruments.

Pentachlorophenol
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
52
17.9
0.006
2.99
2.02
0.1
GC/
MS
41
17.9
0.028
3.45
2.2
GC
11
3.33
0.006
1.25
0.68
*
All
units
are
in
m
g/
L
Summary
of
Semivolatile
Organic
Results
The
four
semivolatile
organic
compounds
analyzed
in
this
report
demonstrate
that
the
available
technologies
for
detecting
these
compounds
at
the
PAL
are
not
sufficient.
The
low
precision
of
these
methods,
exhibited
by
the
wide
range
of
MDLs,
suggests
that
these
analytes
are
difficult
to
detect.
Very
few
laboratories
use
GC
technology
to
detect
the
semivolatile
organic
compounds.
22
More
MDL
results
by
GC
are
necessary
to
draw
any
conclusions
about
the
relationship
between
GC
and
GC/
MS.

Pesticides
Seven
pesticides
were
analyzed
in
this
study:
alachlor,
heptachlor
epoxide,
dichlorodiphenyltrichloroethane
(
DDT),
dimethoate,
heptachlor,
lindane,
and
parathion.
Less
then
ten
MDL
results
were
reported
for
alachlor,
dimethoate,
and
parathion.
The
other
pesticides
had
at
least
forty
MDLs
reported.

Unlike
semivolatile
organic
compounds,
the
methods
for
detecting
pesticides
in
water
were
more
capable
of
detecting
pesticides
at
or
below
the
PALs
(
Figure
5).
It
is
interesting
to
note
that
the
analyte
with
the
highest
PAL,
dimethoate,
resulted
in
the
lowest
percentage
of
results
being
reported
at
or
below
the
PAL.
For
the
other
four
chemicals,
at
least
60%
of
the
MDLs
were
at
or
below
the
respective
PALs.

Figure
5:
Percent
of
Pesticide
MDL
Results
that
Meet
the
PAL
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%

Alachlor
(
PAL
=
0.2
ug/
L)
Heptachlor
Epoxide
(
PAL
=
0.02
ug/
L)
Dimethoate
(
PAL
=
0.4
ug/
L)
Heptachlor
(
PAL
=
0.04
ug/
L)
Lindane
(
PAL
=
0.02
ug/
L)

Chemical
Percentage
All
GC
Table
4
summarizes
laboratories
pesticide
capabilities.
Each
analyte
has
been
subdivided
by
instrument
type
unless
only
one
type
of
instrument
was
reported.

Table
4:
MDL
Quartiles
for
Pesticides
25%
50%
75%
100%
Alachlor
(
all
by
GC)
0.034
0.079
0.232
1.3
Heptachlor
Epoxide
(
all
by
GC)
0.003
0.0074
0.022
0.082
DDT
(
all
instrument
types)
0.0079
0.0144
0.03
0.093
GC
0.0077
0.137
0.03
0.093
Dimethoate
(
all
instrument
types)
0.23
0.377
0.774
0.99
GC
0.19
0.352
0.751
0.99
Heptachlor
(
all
instrument
types)
0.0049
0.009
0.017
0.038
GC
0.0048
0.009
0.016
0.038
23
25%
50%
75%
100%
Lindane
(
all
instrument
types)
0.004
0.0069
0.015
0.06
GC
0.0036
0.0069
0.015
0.06
Parathion
(
all
instrument
types)
0.072
0.15
0.311
2.0
GC
0.063
0.15
0.16
0.69
*
All
units
are
in
m
g/
L
The
following
information
contains
a
statistical
analysis
for
each
pesticide
analyzed
in
this
report.
The
information
includes
the
ranges,
mean,
and
medians
for
each
pesticide.

Alachlor
Although
very
few
laboratories
certified
or
registered
by
the
State
of
Wisconsin
perform
tests
for
alachlor,
it
is
a
widely
used
nitrogen
pesticide
for
broad
leaf
weed
control
in
corn
and
soybean
crops.
A
larger
sample
size
would
produce
more
conclusive
results
about
this
compound.

Alachlor
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
(
all
by
GC)
7
1.3
0.0087
0.27
0.079
0.2
*
All
units
are
in
m
g/
L
DDT
Although
DDT
has
been
banned
in
Wisconsin
since
1970,
it
remains
a
threat
to
wildlife.
DDT
is
very
insoluble
in
water
and
is
seldom
detected
by
laboratories
which
test
water
and
wastewater.
Based
on
a
sample
size
of
42
reported
MDL
results,
50%
reported
a
MDL
of
less
than
0.016
m
g/
L.
The
wildlife
criteria
(
WC)
for
DDT
is
0.000011
m
g/
L.
None
of
the
laboratories
were
able
to
detect
DDT
at
this
low
health­
based
standard.
Most
laboratories
use
GC
to
determine
DDT.

DDT
#
of
Results
Maximum
Minimum
Mean
Median
PAL
WC
Total
40
0.093
0.0009
0.0217
0.0144
NA
0.000011
GC
39
0.093
0.0009
0.0215
0.0137
GC/
MS
1
NA
NA
0.03
NA
*
All
units
are
in
m
g/
L
Dimethoate
Dimethoate
is
a
phosphoric
insecticide
used
on
crops
such
as
corn
and
soybeans;
however,
very
few
laboratories
are
certified
or
registered
by
the
State
to
test
for
this
compound.
As
with
alachlor,
a
larger
sample
size
would
produce
more
conclusive
results.

Dimethoate
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
8
0.99
0.11
0.484
0.377
0.4
GC
6
0.99
0.11
0.471
0.352
GC/
MS
2
0.75
0.3
0.524
NA
*
All
units
are
in
m
g/
L
24
Heptachlor
All
of
the
laboratories
were
capable
of
detecting
heptachlor
below
the
PAL.

Heptachlor
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
40
0.038
0.001
0.012
0.0092
0.04
GC
39
0.038
0.001
0.012
0.009
*
All
units
are
in
m
g/
L
Heptachlor
Epoxide
Heptachlor
epoxide
is
a
degradation
product
of
heptachlor.
Heptachlor
epoxide
has
a
larger
MDL
range
than
heptachlor
implying
that
this
compound
is
more
difficult
to
detect.

Heptachlor
Epoxide
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
(
all
by
GC)
41
0.082
0.001
0.016
0.0074
0.02
*
All
units
are
in
m
g/
L
Lindane
Lindane
is
one
isomer
of
hexachlorobenzene.
Currently
available
GC
and
GC/
MS
technologies
are
sufficiently
sensitive
to
detect
lindane
at
ore
below
the
PAL..

Lindane
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
41
0.06
0.001
0.0128
0.0069
0.02
GC
40
0.06
0.001
0.0127
0.0069
GC/
MS
1
NA
NA
0.02
NA
*
All
units
are
in
m
g/
L
Parathion
Parathion
is
an
orthophosphate
insecticide
which
does
not
have
a
PAL.
It
does
have
an
acute
toxicity
criteria
(
ATC)
for
all
aquatic
life
which
is
0.057
m
g/
L.
Three
of
the
10
results
were
below
the
ATC.
Fifty
percent
(
50%)
of
the
reported
MDLs
were
at
or
below
0.15
m
g/
L.
It
is
difficult
to
draw
more
definitive
conclusions
from
a
sample
size
of
ten
MDL
results.

Parathion
#
of
Results
Maximum
Minimum
Mean
Median
PAL
ATC
Total
10
2
0.019
0.37
0.15
NA
0.057
GC
9
0.69
0.019
0.19
0.15
GC/
MS
1
NA
NA
2.0
NA
*
All
units
are
in
m
g/
L
25
Summary
of
Pesticide
Results
Due
to
the
large
amount
of
agriculture
in
Wisconsin,
accurate
quantitation
of
trace
levels
of
pesticides
in
surface
and
groundwater
is
important.
The
current
technologies
do
an
average
job
of
detecting
these
compounds
at
low
levels.
With
the
limited
number
of
responses
to
the
survey
for
pesticides,
it
is
difficult
to
draw
conclusions
about
current
analytical
capabilities.

Polynuclear
Aromatic
Hydrocarbons
(
PAHs)

The
only
PAH
that
is
on
the
Detection
Reporting
Requirement
list
is
benzo(
a)
pyrene.
This
compound
is
typically
found
near
coal
piles
and
oil
and
gas
spills
and
is
considered
to
be
very
carcinogenic.

Table
5
below
summarizes
the
quartile
information
for
the
PAH
benzo(
a)
pyrene.
The
two
HPLC
methods
for
detecting
this
compound
result
in
substantially
lower
detection
limits
than
GC
or
GC/
MS.

Table
5:
MDL
Quartiles
for
PAHs
25%
50%
75%
100%
Benzo(
a)
pyrene
0.029
0.435
1.33
6.7
GC/
MS
0.6
1.21
2.2
6.7
GC
0.545
1.07
1.29
1.5
HPLC­
UV
0.0181
0.045
0.065
0.22
HPLC­
F
0.0066
0.017
0.03
0.07
*
All
units
are
in
m
g/
L
Below
are
the
ranges,
means,
and
medians
for
benzo(
a)
pyrene.
High­
performance
liquid
chromatography­
fluorescence
(
HPLC­
F)
is
the
only
way
to
consistently
detect
benzo(
a)
pyrene
at
the
PAL
of
0.02
m
g/
L.
More
than
half
of
the
MDL
results
are
reported
by
GC/
MS,
but
none
of
those
results
were
at
or
below
the
PAL.

Benzo(
a)
pyrene
#
of
Results
Maximum
Minimum
Mean
Median
PAL
Total
71
6.7
0.0017
0.92
0.435
0.02
GC/
MS
41
6.7
0.026
1.51
1.24
GC
3
1.5
0.205
0.86
1.07
HPLC­
UV
10
0.22
0.00765
0.066
0.045
HPLC­
F
17
0.07
0.0017
0.021
0.017
*
All
units
are
in
m
g/
L
Polychlorinated
Biphenyls
(
PCBs)

The
final
class
of
chemicals
analyzed
in
this
study
are
polychlorinated
biphenyls
(
PCBs).
Historically,
PCBs
have
found
widespread
industrial
uses
including
as
an
insulator
in
electrical
transformers
and
as
a
dye
solvent
carrier
in
carbonless
copy
paper.
Although
the
sale
and
production
of
PCBs
has
been
banned
in
the
United
States
since
1977
there
are
still
transformers
in
use
that
contain
PCB
contaminated
oil.
The
PCBs
consist
of
a
group
of
similar
congeners
that
26
differ
in
the
number
and
position
of
chlorine
atoms
on
benzene
rings.
PCBs
are
insoluble
in
water,
but
are
found
in
sediment
and
bioaccumulate
in
the
food
chain.
There
are
no
PALs
for
the
seven
congeners
evaluated
in
this
study.
However,
there
is
a
PCB
human
cancer
criteria
(
HCC)
of
0.003
ng/
L
that
can
be
used
for
discussion
purposes.
None
of
the
laboratories
were
able
to
detect
PCBs
down
to
that
level.

Table
6
summarizes
the
PCB
detection
limit
quartiles.
The
quartiles
are
similar
for
each
congener.

Table
6:
MDL
Quartiles
for
PCBs
25%
50%
75%
100%
Aroclor
1016
GC
0.054
0.145
0.255
0.9
Aroclor
1221
GC
0.096
0.167
0.394
1.02
Aroclor
1232
GC
0.088
0.164
0.293
0.71
Aroclor
1242
GC
0.119
0.19
0.325
0.83
Aroclor
1248
GC
0.057
0.182
0.259
0.86
Aroclor
1254
GC
0.055
0.114
0.197
0.81
Aroclor
1260
GC
0.07
0.12
0.223
0.68
*
All
units
are
in
m
g/
L
A
summary
of
the
ranges,
means,
and
medians
for
the
PCBs
is
listed
below
in
Table
7
Table
7:
PCB
Summary
Statistics
#
of
Results
Maximum
Minimum
Mean
Median
Aroclor
1016
46
0.9
0.008
0.186
0.145
Aroclor
1221
39
1.02
0.0175
0.247
0.167
Aroclor
1232
39
0.71
0.018
0.222
0.164
Aroclor
1242
47
0.83
0.01
0.224
0.19
Aroclor
1248
48
0.86
0.0004
0.2
0.182
Aroclor
1254
49
0.806
0.0206
0.16
0.114
Aroclor
1260
52
0.68
0.0071
0.167
0.12
*
All
units
are
in
m
g/
L
**
All
results
by
GC
27
CONCLUSIONS
Detection
limits
vary
considerably,
both
between
laboratories
and
between
procedures.
Different
analytical
technologies
have
different
abilities
to
detect
chemicals
of
concern
at
low
levels.
From
the
information
gathered
for
this
report,
several
important
conclusions
can
be
made
about
the
detection
limit
capabilities
of
Wisconsin
certified
and
registered
laboratories:

¨
 
Of
the
33
compounds
in
this
study,
14
of
them
can
reasonably
be
detected
in
a
clean
water
matrix
at
or
near
levels
of
concern.
They
include:

¨
 
Cadmium
¨
 
Hexavalent
Chromium
¨
 
Lead
¨
 
Mercury
¨
 
1,1,2­
Trichloroethane
¨
 
Bromomethane
¨
 
Chloroform
¨
 
Methylene
Chloride
¨
 
MTBE
¨
 
Alachlor
¨
 
Heptachlor
Epoxide
¨
 
Dimethoate
¨
 
Heptachlor
¨
 
Lindane
¨
 
Of
the
33
compounds
in
this
study,
it
is
possible
to
reliably
quantitate
within
one
order
of
magnitude
6
compounds.
They
include:

¨
 
Thallium
¨
 
1,3­
Dichloropropene
(
cis)
and
1,3­
Dichloropropene
(
trans)

¨
 
Chloromethane
¨
 
Vinyl
Chloride
¨
 
Di(
2­
ethylhexyl)
phthalate
¨
 
Parathion
¨
 
Of
the
33
compounds
in
this
study,
improvements
in
analytical
capability
or
alternate
methodologies
are
necessary
to
detect
14
compounds
at
or
near
the
level
of
concern.
They
include:

¨
 
1,1,2,2­
Tetrachloroethane
¨
 
1,3­
Dichloropropene
(
cis
&
trans)

¨
 
2,4­
Dinitrotoluene
¨
 
2,6­
Dinitrotoluene
¨
 
Pentachlorophenol
¨
 
DDT
¨
 
Benzo(
a)
pyrene
¨
 
PCB
Aroclors
(
1016,
1221,
1232,
1242,
1248,
1254,
1260)
¨
 
26%
of
the
reported
MDLs
could
not
be
used.
The
following
reasons
are
of
most
concern:

¨
 
Spiking
replicate
samples
either
too
high
or
too
low.
28
¨
 
Miscalculating
the
MDL,
either
by
using
the
wrong
Student's
t­
value
or
by
substituting
the
sample
standard
deviation
with
the
population
standard
deviation.

¨
 
Using
less
than
7
replicates
for
the
determination.
¨
 
Only
17%
of
the
laboratories
reported
completely
usable
data.
¨
 
The
detection
limits
for
all
compounds
vary
by
at
least
one
order
of
magnitude.
¨
 
To
detect
metals
at
the
PAL,
ICP/
MS
and
GFAA
consistently
produced
the
best
results.
¨
 
For
volatile
organic
compounds,
when
both
GC
and
GC/
MS
are
used,
neither
technique
is
more
consistent
at
producing
low
MDLs.
¨
 
Both
GC
and
GC/
MS
are
capable
of
consistently
detecting
volatile
organic
compounds
at
the
PAL.
¨
 
Current
instrumentation
is
not
capable
of
detecting
the
low
semivolatile
PALs.
¨
 
HPLC­
F
is
the
only
technique
that
can
consistently
detect
benzo(
a)
pyrene
at
the
PAL.
¨
 
GC
is
capable
of
detecting
PCBs
below
part
per
billion
(
ppb)
levels.

ACKNOWLEDGEMENTS
I
would
like
to
thank
all
of
the
laboratories
in
the
Laboratory
Certification
Program
that
submitted
data
for
this
study.
I
would
also
like
to
thank
the
Laboratory
Certification
Staff
and
Paul
Rasmussen
for
all
of
their
help.
29
REFERENCES
Definition
and
Procedure
for
Determination
of
the
Method
Detection
Limit.
Revision
1.11.
Appendix
B
to
Part
136.
Federal
Register,
49
FR
43430
(
10/
26/
84),
50
FR
694
(
1/
4/
85),
and
51
FR
(
6/
30/
86).

Draper,
W.
M.
ET
AL.
Detection
Limits
of
Organic
Contaminants
in
Drinking
Water.
Journal
AWWA,
90:
6:
82
(
June
1998).

Wisconsin
Department
of
Natural
Resources,
"
Analytical
Detection
Limit
Guidance
and
Laboratory
Guide
for
Determining
Method
Detection
Limits",
PUBL­
TS­
056­
96,
April
1996.
1
APPENDIX
A
DETECTION
REPORTING
REQUIREMENT
1.
INORGANICS
Metals
Antimony
Beryllium
Cadmium
Lead
Thallium
Mercury
Chromium
(
Hexavalent)

2.
ORGANICS
Acids/
Phenols
Pentachlorophenol
(
PCP)

Benzidines
Benzidine
Haloethers
Bis(
chloromethyl)
ether
Nitroaromatics
2,4­
Dinitrotoluene
2,6­
Dinitrotoluene
Polynuclear
Aromatic
Hydrocarbons
Benzo(
a)
pyrene
2.
ORGANICS
Phthalates
&
Adipates
Di(
2­
ethylhexyl)
phthalate
Nonpurgeable
Chlorinated
Hydrocarbons
Hexachlorobenzene
Dioxins/
Furans
Dioxin
PCBs
Polychlorinated
biphenyls
Chlorinated
Pesticides
DDT
and
Metabolites
Heptachlor
Heptachlor
epoxide
Lindane
Toxaphene
Carbamate
Pesticides
Aldicarb
Nitrogen
Pesticides
Alachlor
Dimethoate
Parathion
Trifluralin
2.
ORGANICS
Volatiles
1,1,2,2­
Tetrachloroethane
1,1,2­
Trichloroethane
1,3­
Dichloropropene
(
cis/
trans)
Bromodichloromethane
Bromoform
Bromomethane
Chloroform
Chloromethane
Methyl
tert­
butyl
ether
(
MTBE)
Methylene
Chloride
Vinyl
Chloride
Dibromochloropropane
(
DBCP)
Ethylene
dibromide
(
EDB)
1
APPENDIX
B
APPENDIX
B
TO
PART
136
 
DEFINITION
AND
PROCEDURE
FOR
THE
DETERMINATION
OF
THE
METHOD
DETECTION
LIMIT
 
REVISION
1.11
Definition
The
method
detection
limit
(
MDL)
is
defined
as
the
minimum
concentration
of
a
substance
that
can
be
measured
and
reported
with
99%
confidence
that
the
analyte
concentration
is
greater
than
zero
and
is
determined
from
analysis
of
a
sample
in
a
given
matrix
containing
the
analyte.

Scope
and
Application
This
procedure
is
designed
for
applicability
to
a
wide
variety
of
sample
types
ranging
from
reagent
(
blank)
water
containing
analyte
to
wastewater
containing
analyte.
The
MDL
for
an
analytical
procedure
may
vary
as
a
function
of
sample
type.
The
procedure
requires
a
complete,
specific,
and
well
defined
analytical
method.
It
is
essential
that
all
sample
processing
steps
of
the
analytical
method
be
included
in
the
determination
of
the
method
detection
limit.

The
MDL
obtained
by
this
procedure
is
used
to
judge
the
significance
of
a
single
measurement
of
a
future
sample.

The
MDL
procedure
was
designed
for
applicability
to
a
broad
variety
of
physical
and
chemical
methods.
To
accomplish
this,
the
procedure
was
made
device­
or
instrument­
independent.

Procedure
1.
Make
an
estimate
of
the
detection
limit
using
one
of
the
following:
(
a)
The
concentration
value
that
corresponds
to
an
instrument
signal/
noise
in
the
range
of
2.5
to
5.
(
b)
The
concentration
equivalent
of
three
times
the
standard
deviation
of
replicate
instrumental
measurements
of
the
analyte
in
reagent
water.
(
c)
That
region
of
the
standard
curve
where
there
is
a
significant
change
in
sensitivity,
i.
e.,
a
break
In
the
slope
of
the
standard
curve.
(
d)
Instrumental
limitations.

It
is
recognized
that
the
experience
of
the
analyst
is
important
to
this
process.
However,
the
analyst
must
include
the
above
considerations
in
the
initial
estimate
of
the
detection
limit.

2.
Prepare
reagent
(
blank)
water
that
is
as
free
of
analyte
as
possible.
Reagent
or
interference
free
water
is
defined
as
a
water
sample
in
which
analyte
and
interferant
concentrations
are
not
detected
at
the
method
detection
limit
of
each
analyte
of
interest.
Interferences
are
defined
as
systematic
errors
in
the
measured
analytical
signal
of
an
established
procedure
caused
by
the
presence
of
interfering
species
(
interferant).
The
interferant
concentration
is
presupposed
to
be
normally
distributed
in
representative
samples
of
a
give
matrix.

3.
(
a)
If
the
MDL
is
to
be
determined
in
reagent
(
blank)
water,
prepare
a
laboratory
standard
(
analyte
in
reagent
water)
at
a
concentration
which
is
at
least
equal
to
or
in
the
same
concentration
range
as
the
estimated
detection
limit.
(
Recommend
between
1
and
5
times
the
estimated
detection
limit.)
Proceed
to
Step
4.
(
b)
If
the
MDL,
is
to
be
determined
in
another
sample
matrix,
analyze
the
sample.
If
the
measured
level
of
the
analyte
is
in
the
recommended
range
of
one
to
five
times
the
estimated
detection
limit,
proceed
to
Step
4.

If
the
measured
level
of
analyte
is
less
than
the
estimated
detection
limit,
add
a
known
amount
of
analyte
to
bring
the
level
of
analyte
between
one
and
five
times
the
estimated
detection
limit.

If
the
measured
level
of
analyte
is
greater
than
five
times
the
estimated
detection
limit,
there
are
two
options.
(
1)
Obtain
another
sample
with
a
lower
level
of
analyte
in
the
same
matrix
if
possible.
(
2)
This
sample
may
be
used
as
is
for
determining
the
method
detection
limit
if
the
analyte
level
does
not
exceed
10
times
the
MDL
of
the
analyte
in
reagent
water.
The
variance
of
the
analytical
method
changes
as
the
analyte
concentration
increases
from
the
MDL,
hence
the
MDL
determined
under
these
circumstances
may
not
truly
reflect
method
variance
at
lower
analyte
concentrations.

4.
(
a)
Take
a
minimum
of
seven
aliquots
of
the
sample
to
be
used
to
calculate
the
method
detection
limit
and
process
each
through
the
entire
analytical
method.
Make
all
computations
according
to
the
defined
method
with
final
results
in
the
method
reporting
units.
If
a
blank
measurement
is
required
to
calculate
the
measured
level
of
analyte,
obtain
a
separate
blank
measurement
for
each
sample
aliquot
analyzed.
The
average
blank
measurement
is
subtracted
from
the
respective
sample
measurements.
(
b)
It
may
be
economically
and
technically
desirable
to
evaluate
the
estimated
method
detection
limit
before
proceeding
with
4a.
This
will:
(
1)
Prevent
repeating
this
entire
procedure
when
the
costs
of
analyses
are
high
and
(
2)
insure
that
the
procedure
is
being
conducted
at
the
correct
concentration.
It
is
quite
possible
that
an
inflated
MDL
will
be
calculated
from
data
obtained
at
many
times
the
real
MDL
even
though
the
level
of
analyte
is
less
than
five
times
the
calculated
method
detection
limit.
To
insure
that
the
estimate
of
the
method
detection
limit
is
a
good
estimate,
it
is
necessary
to
determine
that
a
lower
concentration
of
analyte
will
not
result
in
a
significantly
lower
concentration
of
analyte
will
not
result
in
significant
lower
method
detection
limit.
Take
two
aliquots
of
the
sample
to
be
used
to
calculate
the
method
detection
limit
and
process
each
through
the
entire
method,
including
blank
measurements
as
described
above
in
4a.
Evaluate
these
data:
(
1)
If
these
measurements
indicate
the
sample
is
in
desirable
range
for
determination
of
the
MDL,
take
five
additional
aliquots
and
proceed.
Use
all
seven
measurements
for
calculation
of
the
MDL.
(
2)
If
these
measurements
indicate
the
sample
is
not
in
correct
range,
reestimate
the
MDL,
obtain
new
sample
as
in
3
and
repeat
either
4a
or
4b.

5.
Calculate
the
variance
(
S2)
and
standard
deviation
(
S)
of
the
replicate
measurements
as
follows:
2
S=(
S2)
½
where:

Xi;
i=
1
to
n,
are
the
analytical
results
in
the
final
method
reporting
units
obtained
from
the
sample
aliquots
and
S
refers
to
the
sum
of
the
X
values
from
i=
1
to
n.

6.
(
a)
Compute
the
MDL,
as
follows:

MDL=
t(
n­
1,1­
µ
=
0.99)
(
S)
where:
MDL
=
the
method
detection
limit
t(
n­
1,
µ
­
1=
0.99)
=
the
students'
t
value
appropriate
for
a
99%
confidence
level
and
a
standard
deviation
estimate
with
n­
1
degrees
of
freedom.
See
Table.
S
=
standard
deviation
of
the
replicate
analyses.

(
b)
The
95%
confidence
interval
estimates
for
the
MDL,
derived
in
6a
are
computed
according
to
the
following
equations
derived
from
percentiles
of
the
chi
square
over
degrees
of
freedom
distribution
(
X2/
df).
LCL
=
0.64
MDL
UCL
=
2.20
MDL
where:
LCL
and
UCL
are
the
lower
and
upper
95%
confidence
limits
respectively
based
on
seven
aliquots.

7.
Optional
iterative
procedure
to
verify
the
reasonableness
of
the
estimate
of
the
MDL
and
subsequent
MDL
determinations.
(
a)
If
this
is
the
initial
attempt
to
compute
MDL
based
on
the
estimate
of
MDL
formulated
MDL
based
on
the
estimate
of
MDL
formulated
in
Step
1,
take
the
MDL
as
calculated
in
Step
6,
spike
the
matrix
at
this
calculated
MDL
and
proceed
through
the
procedure
starting
with
Step
4.
(
b)
If
this
is
the
second
or
later
iteration
of
the
MDL
calculation,
use
S2
from
the
current
MDL
calculation
and
S2
from
the
previous
MDL
calculation
to
compute
the
F­
ratio.
The
F­
ratio
is
calculated
by
substituting
the
larger
S2
into
the
numerator
S2
A
and
the
other
into
the
denominator
S2
B.
The
computed
F­
ratio
is
then
compared
with
the
F­
ratio
found
in
the
table
which
is
3.05
as
follows:
if
S2
A/
S2
B<
3.05,
then
compute
the
pooled
standard
deviation
by
the
following
equation:

If
S2
A/
S2
B>
3.05,
respike
at
the
most
recent
calculated
MDL
and
process
the
samples
through
the
procedure
starting
with
Step
4.
If
the
most
recent
calculated
MDL
does
not
permit
qualitative
identification
when
samples
are
spiked
at
that
level,
report
the
MDL
as
a
concentration
between
the
current
and
previous
MDL
which
permits
qualitative
identification.
(
c)
Use
the
Spooled
as
calculated
in
7b
to
compute
the
final
MDL
according
to
the
following
equation:

MDL=
2.681(
Spooled)
where
2.681
is
equal
to
t(
12,1­
µ
=
.99).

(
d)
The
95%
confidence
limits
for
MDL
derived
in
7c
are
computed
according
to
the
following
equations
derived
from
percentiles
of
the
chi
squared
over
degrees
of
freedom
distribution.
LCL=
0.72
MDL
UCL=
1.65
MDL
where
LCL
and
UCL
are
the
lower
and
upper
95%
confidence
limits
respectively
based
on
14
aliquots.

TABLES
OF
STUDENTS'
t
VALUES
AT
THE
99
PERCENT
CONFIDENCE
LEVEL
Number
of
replicates
Degrees
of
freedom
(
n­
1)
t(
n­
1,
.99)

7
..........................................................................
6
3.143
2
i=
1
i
2
2
i=
1
i
S
=
1
n
­
1
n
X
­
n
X
/
n
å
å
æ
è
ç
ç
ö
ø
÷
÷
é
ë
ê
ê
ê
ù
û
ú
ú
ú
pooled
1/
2
2
A
2
B
S
=
6(
S
)
+
6(
S
)

12
é
ë
ê
ù
û
ú
3
8
..........................................................................
7
2.998
9
..........................................................................
8
2.896
10
........................................................................
9
2.821
11
........................................................................
10
2.764
16
........................................................................
15
2.002
21
........................................................................
20
2.528
26
........................................................................
25
2.485
31
........................................................................
30
2.457
61
........................................................................
60
2.390
¥
.
.........................................................................
¥
2.326
Reporting
The
analytical
method
used
must
be
specifically
identified
by
number
of
title
and
the
MDL
for
each
analyte
expressed
in
the
appropriate
method
reporting
units.
If
the
analytical
method
permits
options
which
affect
the
method
detection
limit,
these
conditions
must
be
specified
with
the
MDL
value.
The
sample
matrix
used
to
determine
the
MDL
must
also
be
identified
with
MDL
value.
Report
the
mean
analyte
level
with
the
MDL
and
indicate
if
the
MDL
procedure
was
iterated.
If
a
laboratory
standard
or
a
sample
that
contained
a
known
amount
analyte
was
used
for
this
determination,
also
report
eh
mean
recovery.

If
the
level
of
analyte
in
the
sample
was
below
the
determined
MDL
or
exceeds
10
times
the
MDL
of
the
analyte
in
reagent
water,
do
not
report
a
value
for
the
MDL.

[
49
FR
43430,
Oct.
265,
1984;
50
FR
694,
696,
Jan.
4
1985,
as
amended
at
51
FR
23703,
June
30,
1986]
Adapted
from
the
Code
of
Federal
Regulations
by
the
Wisconsin
Department
of
Natural
Resources
1
APPENDIX
C
Appendix
C
contains
a
sample
copy
of
the
request
letter
and
a
blank
spreadsheet
that
were
sent
to
the
laboratories
that
participated
in
the
study.
1
1/
13/
98
FID
SUBJECT:
Low
Level
Detection
Reporting
Requirement
Information
Request
Dear
Section
NR
149.11(
5)
and
NR
149.15
Wis.
Adm.
Code,
require
certified
or
registered
laboratories
to
have
determined
their
limit
of
detection
(
LOD)
and
limit
of
quantitation
(
LOQ)
for
substances
on
the
Detection
Reporting
Requirement
list
by
January
1,
1997.
Consequently,
in
accordance
with
section
NR
149.06(
3)
of
the
Laboratory
Certification
code,
we
are
requiring
that
all
laboratories
currently
certified
or
registered
for
any
of
the
substances
on
the
list
submit
their
LOD
and
LOQ
for
those
substances
in
a
water
matrix.

The
substances
on
the
list
which
your
laboratory
is
currently
certified
or
registered
for
are
listed
below.
You
will
need
to
submit
both
an
LOD
and
LOQ
for
these
substances.
In
addition,
your
laboratory
must
report
1)
the
analytical
method
used,
2)
how
the
LOD
and
LOQ
were
calculated
and
3)
any
analytical
judgment
or
reasoning
used
to
adjust
or
average
the
values.
We
strongly
encourage
the
use
of
the
enclosed
diskette,
which
contains
an
electronic
spreadsheet,
to
submit
this
information,
but
will
accept
paper
reports
if
your
lab
cannot
use
it.
Simply
open
the
file
(
a:\
lodreqst.
wq1)
in
your
spreadsheet
program
(
Excel,
QuattroPro,
Lotus
123,
etc.)
and
fill
out
the
appropriate
sections
for
the
analytes
listed
in
the
table
below.
Save
the
changes
to
the
same
3.5"
disk
and
mail
it
using
the
enclosed
disk
mailer.

Category
#
Group
Analytes
08
Metal
Cadmium
08
Metal
Lead
08
Metal
Mercury
08
Metal
Thallium
10
Volatile
1,1,2,2­
Tetrachloroethane
10
Volatile
Chloroform
10
Volatile
Methylene
Chloride
10
Volatile
Vinyl
Chloride
11
Acid
Phenol
Pentachlorophenol
by
GC
13
PAH
Benzo(
a)
pyrene
by
HPLC
15
Petro.
Volatile
Methyl
tert­
butyl
ether
(
MTBE)
18
SDWA
Metal
Beryllium
in
Drinking
Water
18
SDWA
Metal
Cadmium
in
Drinking
Water
18
SDWA
Metal
Lead
in
Drinking
Water
All
data
must
be
received
by
the
Laboratory
Certification
Program
within
60
days
of
the
date
of
this
letter.

Please
contact
either
Mike
Kvitrud
at
(
608)
261­
8459
or
Jeff
Ripp
at
(
608)
267­
0579
of
my
staff
if
you
have
any
questions.

Sincerely,

John
R.
Sullivan,
Chief
Analytical
and
Statistical
Services
Bureau
of
Integrated
Science
Services
Printed
on
Recycled
Paper
Quality
Natural
Resources
Management
Through
Excellent
Customer
Service
State
of
Wisconsin
\
DEPARTMENT
OF
NATURAL
RESOURCES
Tommy
G.
Thompson,
Governor
George
E.
Meyer,
Secretary
Box
7921
101
South
Webster
Street
Madison,
Wisconsin
53707­
7921
TELEPHONE
608­
266­
2621
FAX
608­
267­
3579
TDD
608­
267­
6897
2