Metals_EPA_200_8_FINAL_03_09_2022

Metals – EPA 200.8 Page 1
Revised 03/09/2022
NC DEQ/DWR WASTEWATER/GROUNDWATER LABORATORY CERTIFICATION BRANCH

LABORATORY NAME: CERT #:
PRIMARY ANALYST: DATE:
NAME OF PERSON COMPLETING CHECKLIST (PRINT):
SIGNATURE OF PERSON COMPLETING CHECKLIST:

Parameter: Metals by ICP-MS
Method: EPA Method 200.8, Rev. 5.4 (1994) (Aqueous and Non-aqueous)

Note: Per November 7, 2007 EPA letter, additional metals that are not in Table 1.1 may be analyzed as long as QC is acceptable

Equipment:
Inductively coupled plasma mass
spectrometer Analytical balance, capable to
measure 0.1 mg Temperature adjustable hot plate
capable of maintaining 95 °C
Drying oven capable of maintaining
105 ± 5 °C
(Optional) Air displacement pipettor
capable of delivering volumes from
0.1-2500 µL with an assortment of
high-quality disposable pipet tips

(Optional) Temperature adjustable
block digester capable of maintaining
95 °C equipped with 250 mL
constricted digestion tubes
Mortar and pestle, ceramic or
nonmetallic material Polypropylene sieve, 5-mesh (4 mm
opening) Labware

PLEASE COMPLETE CHECKLIST IN INDELIBLE INK
Please mark Y, N or NA in the column labeled LAB to indicate the common lab practice and in the column labeled SOP to
indicate whether it is addressed in the SOP.
GENERAL
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EXPLANATION
1
Is the SOP reviewed at least every 2 years? What is the most recent
review/revision date of the SOP? [15A NCAC 02H .0805 (a) (7)]

Date:

Quality assurance, quality control, and
Standard Operating Procedure documentation
shall indicate the effective date of the
document and be reviewed every two years
and updated if changes in procedures are
made.

Verify proper method reference. During review
notate deviations from the approved method
and SOP.
2 Are all review/revision dates and procedural edits tracked and
documented? [15A NCAC 02H .0805 (a) (7)]
Each laboratory shall have a formal process to
track and document review dates and any
revisions made in all quality assurance, quality
control, and Standard Operating Procedure
documents.
3 Is there North Carolina data available for review? If not, review PT data
PRESERVATION and STORAGE
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EXPLANATION
4
What type of sample container is used? [40 CFR 136.3 Table II]

Answer:

Silica requires polyethylene or quartz. Boron
requires polyethylene, fluoropolymer (PTFE,
Teflon®), or quartz. All others require
polyethylene, fluoropolymer (PTFE, Teflon®),
or glass.
5 Are samples (except Silica) analyzed within 6 months of collection?
[40 CFR 136.3 Table II]
6 Are Silica samples analyzed within 28 days? [40 CFR 136.3 Table II]
7 Are aqueous samples (except Silica) preserved with HNO3 to pH <2
S.U. within 15 minutes of collection? [40 CFR 136.3 Table II]
8
If not, are they (except for Boron and Silica) preserved with HNO3 to
pH <2 S.U. at least 24 hours prior to analysis? [40 CFR 136.3 Table
II]

40 CFR does not make this allowance for
Boron, so it must be preserved within 15
minutes.
9
Are aqueous samples (except Silica and boron) verified and
documented to be at a pH <2 for at least 24 hours prior to the start of
analyses? [40 CFR 136.3 Table II and Footnote 19] [15A NCAC
02H .0805 (a) (7) (M)]

Footnote 19: An aqueous sample may be
collected and shipped without acid
preservation. However, acid must be added at
least 24 hours before analysis to dissolve any
metals that adsorb to the container walls. If the
sample must be analyzed within 24 hours of
collection, add the acid immediately (see
Metals – EPA 200.8 Page 2
Revised 03/09/2022
footnote 2). Soil and sediment samples do not
need to be preserved with acid. The
allowances in this footnote supersede the
preservation and holding time requirements in
the approved metals methods.
10 Are Silica samples iced to above freezing but ≤ 6 º C during
shipment? [40 CFR 136.3 Table II] Silica samples are not acid preserved and
must be refrigerated.
11 Are Silica samples refrigerated above freezing but ≤ 6 ºC during
storage? [40 CFR 136.3 Table II]
12
For dissolved metals, are the samples filtered through a 0.45 µm filter
within 15 minutes of collection and before preservation with HNO3 to
pH <2 S.U.? [40 CFR 136.3 Table II Footnote 7]

PROCEDURE – Interferences
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13
If alternative analytical isotopes (other than those in Table 4) having
higher natural abundance are selected in order to achieve greater
sensitivity are chosen, is the data corrected by measuring the signal
from another isotope of the interfering element and subtracting the
appropriate signal ratio from the isotope of interest? [EPA Method
200.8, Rev. 5.4 (1994), Section 4.1.1]

Isobaric elemental interferences are caused by
isotopes of different elements which form
singly or doubly charged ions of the same
nominal mass-to-charge ratio and which
cannot be resolved by the mass spectrometer
in use. All elements determined by this method
have, at a minimum, one isotope free of
isobaric elemental interference. Of the
analytical isotopes recommended for use with
this method (Table 4), only molybdenum-98
(ruthenium) and selenium-82 (krypton) have
isobaric elemental interferences. A record of
this correction process should be included with
the report of the data. It should be noted that
such corrections will only be as accurate as
the accuracy of the isotope ratio used in the
elemental equation for data calculations.
Relevant isotope ratios should be established
prior to the application of any corrections.
14 Is the spectrometer resolution adjusted to minimize wing overlap
interferences? [EPA Method 200.8, Rev. 5.4 (1994), Section 4.1.2]
Abundance sensitivity - Is a property defining
the degree to which the wings of a mass peak
contribute to adjacent masses. The abundance
sensitivity is affected by ion energy and
quadrupole operating pressure. Wing overlap
interferences may result when a small ion
peak is being measured adjacent to a large
one.
15
When isobaric polyatomic ion interferences (see Table 2) cannot be
avoided by the selection of alternative analytical isotopes, are
corrections made to the data? [EPA Method 200.8, Rev. 5.4 (1994),
Section 4.1.3]

Isobaric polyatomic ion interferences - Are
caused by ions consisting of more than one
atom which have the same nominal mass-to-
charge ratio as the isotope of interest, and
which cannot be resolved by the mass
spectrometer in use. These ions are commonly
formed in the plasma or interface system from
support gases or sample components.
Equations for the correction of data should be
established at the time of the analytical run
sequence as the polyatomic ion interferences
will be highly dependent on the sample matrix
and chosen instrument conditions. In
particular, the common 82Kr interference that
affects the determination of both arsenic and
selenium, can be greatly reduced with the use
of high purity krypton free argon.
16 Are internal standards used to compensate for physical interference
effects? [EPA Method 200.8, Rev. 5.4 (1994), Section 4.1.4]
Physical interferences may occur in the
transfer of solution to the nebulizer (e.g.,
viscosity effects), at the point of aerosol
formation and transport to the plasma (e.g.,
surface tension), or during excitation and
ionization processes within the plasma itself.
High levels of dissolved solids in the sample
may contribute deposits of material on the
extraction and/or skimmer cones reducing the
effective diameter of the orifices and therefore
ion transmission. Dissolved solids levels not
Metals – EPA 200.8 Page 3
Revised 03/09/2022
exceeding 0.2% (w/v) have been
recommended to reduce such effects. Internal
standards ideally should have similar analytical
behavior to the elements being determined.
17 Are suitable rinse times used to minimize memory interferences?
[EPA Method 200.8, Rev. 5.4 (1994), Section 4.1.5]
The rinse times necessary for a particular
element should be estimated prior to analysis.
This may be achieved by aspirating a standard
containing elements corresponding to 10 times
the upper end of the linear range for a normal
sample analysis period, followed by analysis of
the rinse blank at designated intervals. The
length of time required to reduce analyte
signals to within a factor of 10 of the method
detection limit, should be noted. Memory
interferences may also be assessed within an
analytical run by using a minimum of three
replicate integrations for data acquisition. If the
integrated signal values drop consecutively,
the analyst should be alerted to the possibility
of a memory effect, and should examine the
analyte concentration in the previous sample
to identify if this was high. If a memory
interference is suspected, the sample should
be reanalyzed after a long rinse period. In the
determination of mercury, which suffers from
severe memory effects, the addition of 100
µg/L gold will effectively rinse 5 µg/L mercury
in approximately two minutes. Higher
concentrations will require a longer rinse time.
18 Are all acids used ultra high-purity grade? [EPA Method 200.8, Rev.
5.4 (1994), Section 7.1]
Reagents may contain elemental impurities
that might affect the integrity of analytical data.
Owing to the high sensitivity of ICP-MS, high-
purity reagents should be used whenever
possible.
19
When hydrochloric acid is used, are corrections for the chloride
polyatomic ion interferences applied to all data? [EPA Method 200.8,
Rev. 5.4 (1994), Section 7.1]

Nitric acid is preferred for ICP-MS in order to
minimize polyatomic ion interferences. Several
polyatomic ion interferences result when
hydrochloric acid is used (Table 2), however, it
should be noted that hydrochloric acid is
required to maintain stability in solutions
containing antimony and silver.

PROCEDURE – Sample Preparation
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EXPLANATION
20 Are samples digested/extracted prior to analysis? [EPA Method
200.8, Rev. 5.4 (1994), Section 1.5]
21
Are samples containing suspended or particulate material ≥1% (w/v)
extracted as a solid type sample? [EPA Method 200.8, Rev. 5.4
(1994), Section 1.5 and 11.2.2]

A well-mixed, acid preserved aliquot
containing no more than 1 g particulate
material should be cautiously evaporated to
near 10 mL and extracted using the acid
mixture procedure described in sections 11.3.3
through 11.3.6.
22
For the analysis of silver, are samples with concentrations >0.1 mg/L
or >50 mg/kg, diluted to be below this concentration? [EPA Method
200.8, Rev. 5.4 (1994), Section 1.7]

PROCEDURE – Sample Preparation – Dissolved Metals
L
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EXPLANATION
23
Is a ≥20 mL aliquot of a filtered and acid preserved sample pipetted
into a 50 mL polypropylene centrifuge tube? [EPA Method 200.8,
Rev. 5.4 (1994), Section 11.1.1]

24
If a precipitate is formed during acidification, transport, or storage, is
the sample aliquot treated using the procedure for total recoverable
metals prior to analysis? [EPA Method 200.8, Rev. 5.4 (1994),
Section 11.1.1]
See method sections 11.2.2 through 11.2.8.
25
Is an appropriate volume of (1+1) nitric acid added to adjust the acid
concentration of the aliquot to approximate a 1% (v/v) nitric acid
solution? [EPA Method 200.8, Rev. 5.4 (1994), Section 11.1.1]
For example, add 0.4 mL (1+1) HNO3 to a 20
mL aliquot of sample.
Metals – EPA 200.8 Page 4
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26
If the direct addition procedure (Method A, Section 10.3) is being
used, are internal standards added? [EPA Method 200.8, Rev. 5.4
(1994), Section 11.1.1]

27 Is the tube capped and mixed prior to sample analysis? [EPA
Method 200.8, Rev. 5.4 (1994), Section 11.1.1] The sample is now ready for analysis.
PROCEDURE – Sample Preparation – Total Metals (aqueous)
L
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EXPLANATION
28
What initial volumes of sample are used?

ANSWER:

29
Is a well-mixed acid preserved sample transferred to an appropriate
digestion vessel? [EPA Method 200.8, Rev. 5.4 (1994), Section
11.2.2]

Although the method calls for 100 mL, smaller
sample aliquot volumes may be used under
method flexibility allowances.
30
Is 2 mL of (1+1) nitric acid and 1.0 mL of (1+1) hydrochloric acid
added to the beaker? [EPA Method 200.8, Rev. 5.4 (1994), Section
11.2.3]
If a smaller sample volume is used, proper
ratios of acids must be maintained.
31
Is the beaker placed on a hot plate at 85 °C in a fume hood and
covered with an elevated watch glass to prevent contamination?
[EPA Method 200.8, Rev. 5.4 (1994), Section 11.2.3]

For proper heating adjust the temperature
control of the hot plate such that an uncovered
Griffin beaker containing 50 mL of water
placed in the center of the hot plate can be
maintained at a temperature approximately but
no higher than 85 °C. Once the beaker is
covered with a watch glass the temperature of
the water will rise to approximately 95 °C.

Using a hotblock and digestion tubes is a
method modification allowed under 40 CFR
Part 136.6.
32
Is the sample volume reduced to about 20 mL by gentle heating at
85 °C (not boiling)? [EPA Method 200.8, Rev. 5.4 (1994), Section
11.2.4]

This step takes about two hours for a 100 mL
aliquot. The rate of evaporation rapidly
increases as the sample volume approaches
20 mL.
33
Is the beaker then covered with a watch glass to prevent additional
evaporation and gently refluxed for 30 minutes? [EPA Method 200.8,
Rev. 5.4 (1994), Section 11.2.5]

Slight boiling may occur, but vigorous boiling
must be avoided to prevent loss of the HCl-
H2O azeotrope.
34
After cooling, what volume are samples brought to after digestion?
[EPA Method 200.8, Rev. 5.4 (1994), Section 11.2.6]

ANSWER:

The method states to start with 100 mL and
bring post-digestion volume to 50 mL. Smaller
initial volumes may be used, and final volumes
may be returned to the initial volume to avoid
concentration calculations.
35 Is undissolved material allowed to settle overnight or centrifuged?
[EPA Method 200.8, Rev. 5.4 (1994), Section 11.2.7]
The sample is now ready for analysis. All
analyses should be performed ASAP after
preparation. If the sample still contains
suspended solids that would clog the
nebulizer, a portion of the sample may be
filtered prior to analysis. However, care should
be exercised to avoid contamination from
filtration.
36
How is chloride interference mitigated? [EPA Method 200.8, Rev. 5.4
(1994), Section 11.2.8]

ANSWER:

Prior to analysis, adjust the chloride
concentration by pipetting 20 mL of the
prepared solution into a 50 mL volumetric
flask, dilute to volume with reagent water and
mix.

If the dissolved solids in this solution
are >0.2%, additional dilution may be required
to prevent clogging of the extraction and/or
skimmer cones.

Note: some instruments (such as Perkin
Elmer) have an internal method of eliminating
chloride interference. When using this feature,
dilute the digested solution back to the original
predigested volume rather than performing this
step. However, before employing this method,
laboratories must perform a comparison of
samples with and without the technology to
show that it won’t reduce sensitivity or cause a
Metals – EPA 200.8 Page 5
Revised 03/09/2022
magnification of other interferences

37
If the direct addition procedure (Method A, Section 10.3) is being
used, are internal standards added? [EPA Method 200.8, Rev. 5.4
(1994), Section 11.2.8]

The sample is now ready for analysis.
Because the effects of various matrices on the
stability of diluted samples cannot be
characterized, all analyses should be
performed as soon as possible after the
completed preparation.
PROCEDURE – Sample Preparation – Total Metals
(non-aqueous)
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38
Is a portion (>20 g) of mixed sample weighed, dried to a constant
weight at 60 °C, and weighed again to determine the percent solids?
[EPA Method 200.8, Rev. 5.4 (1994), Section 11.3.1]

For samples <35% moisture, a 20 g portion is
sufficient. For samples >35% moisture, a
larger aliquot 50-100 g is required.

%Solids = Dried Weight X100
Wet Weight
39
Is the dried sample sieved using a 5-mesh polypropylene sieve and
ground in a mortar and pestle? [EPA Method 200.8, Rev. 5.4 (1994),
Section 11.3.2]
The sieve, mortar, and pestle should be
cleaned between samples.
40
Is 1.0 ± 0.01 g of the dried, ground material transferred to a 250 mL
Phillips beaker? [EPA Method 200.8, Rev. 5.4 (1994), Section
11.3.2]

41 Is 4 mL of (1+1) HNO3 and 10 mL of (1+4) HCL added to the
beaker? [EPA Method 200.8, Rev. 5.4 (1994), Section 11.3.3]
42
Is the beaker placed on a hot plate at 85 °C in a fume hood, covered
with a watch glass, and gently refluxed for 30 minutes? [EPA Method
200.8, Rev. 5.4 (1994), Section 11.3.4]

For proper heating adjust the temperature
control of the hot plate such that an uncovered
Griffin beaker containing 50 mL of water
placed in the center of the hot plate can be
maintained at a temperature approximately but
no higher than 85°C. Once the beaker is
covered with a watch glass the temperature
will rise to approximately 95 °C. Very slight
boiling may occur, however vigorous boiling
must be avoided. Some evaporation will occur
(3-4 mL). Also, a block digester capable of
maintaining a temperature of 95°C and
equipped with 250 mL constricted volumetric
digestion tubes may be substituted for the hot
plate and conical beakers in the extraction
step.
43
After cooling, is the extract diluted to 100 mL in a volumetric flask
and mixed well? [EPA Method 200.8, Rev. 5.4 (1994), Section
11.3.5]

44
Is the solution allowed to stand overnight to separate insoluble
material or centrifuged? [EPA Method 200.8, Rev. 5.4 (1994),
Section 11.3.6]

If after centrifuging or standing overnight the
extract solution contains suspended solids that
would clog the nebulizer, a portion of the
extract solution may be filtered for their
removal prior to analysis. However, care
should be exercised to avoid potential
contamination from filtration.
45
How is chloride interference mitigated? [EPA Method 200.8, Rev. 5.4
(1994), Section 11.3.7]

ANSWER:

Prior to analysis, adjust the chloride
concentration by pipetting 20 mL of the
prepared solution into a 100 mL volumetric
flask, dilute to volume with reagent water and
mix.

If the dissolved solids in this solution are
>0.2%, additional dilution may be required to
prevent clogging of the extraction and/or
skimmer cones.
46
If the direct addition procedure (Method A, Section 10.3) is being
used, are internal standards added? [EPA Method 200.8, Rev. 5.4
(1994), Section 11.3.7]

The sample is now ready for analysis.
Because the effects of various matrices on the
stability of diluted samples cannot be
characterized, all analyses should be
performed as soon as possible after the
completed preparation. Determine the percent
solids in the sample for use in calculations and
for reporting data on a dry weight basis.
Metals – EPA 200.8 Page 6
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PROCEDURE – Instrument Calibration
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47 Are the manufacturer recommended operating conditions followed?
[EPA Method 200.8, Rev. 5.4 (1994), Section 10.1]
Because of the diversity of instrument
hardware, no detailed instrument operating
conditions are provided. It is the responsibility
of the analyst to verify that the instrument
configuration and operating conditions satisfy
the analytical requirements and to maintain
quality control data verifying instrument
performance and analytical results.
48
Is the precalibration routine completed prior to calibrating the
instrument until such time that instrument stability can be
demonstrated periodically by running the tuning solution (Section
7.7) a minimum of five times with resulting relative standard
deviations of absolute signals for all analytes of less than 5%? [EPA
Method 200.8, Rev. 5.4 (1994), Section 10.2]

Initiate proper operating configuration of
instrument and data system. Allow a period of
not less than 30 minutes for the instrument to
warm up. During this process conduct mass
calibration and resolution checks using the
tuning solution. Resolution at low mass is
indicated by magnesium isotopes 24, 25, and
26. Resolution at high mass is indicated by
lead isotopes 206, 207, and 208. For good
performance adjust spectrometer resolution to
produce a peak width of approximately 0.75
amu at 5% peak height. Adjust mass
calibration if it has shifted by more than 0.1
amu from unit mass.
49
Is internal standardization used in all analyses to correct for
instrument drift and physical interferences? [EPA Method 200.8,
Rev. 5.4 (1994), Section 10.3]

For full mass range scans, a minimum of three
internal standards must be used. Procedures
described in this method for general
application, detail the use of five internal
standards; scandium, yttrium, indium, terbium
and bismuth. These were used to generate the
precision and recovery data attached to this
method. Internal standards must be present in
all samples, standards and blanks at identical
levels. This may be achieved by directly
adding an aliquot of the internal standards to
the CAL standard, blank or sample solution
(Method A, Section 10.3), or alternatively by
mixing with the solution prior to nebulization
using a second channel of the peristaltic pump
and a mixing coil (Method B, Section 10.3).
The concentration of the internal standard
should be sufficiently high that good precision
is obtained in the measurement of the isotope
used for data correction and to minimize the
possibility of correction errors if the internal
standard is naturally present in the sample.
Depending on the sensitivity of the instrument,
a concentration range of 20-200 µg/L of each
internal standard is recommended. Internal
standards should be added to blanks, samples
and standards in a like manner, so that dilution
effects resulting from the addition may be
disregarded.
50 Are a minimum of three replicate integrations used for data
acquisition? [EPA Method 200.8, Rev. 5.4 (1994), Section 10.4]
51 Is the average of the integrations used for instrument calibration and
data reporting? [EPA Method 200.8, Rev. 5.4 (1994), Section 10.4]
52
Is the rinse blank used to flush the system between solution changes
for blanks, standards and samples? [EPA Method 200.8, Rev. 5.4
(1994), Section 10.5]

Allow sufficient rinse time to remove traces of
the previous sample (Section 4.1.5). Solutions
should be aspirated for 30 seconds prior to the
acquisition of data to allow equilibrium to be
established.
53 Is the instrument tuned and calibrated for all analytes of interest?
[EPA Method 200.8, Rev. 5.4 (1994), Section 11.4.2]
PROCEDURE – Sample Analysis
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54 For all sample analyses, is a minimum of three replicate integrations
used for data acquisition? [EPA Method 200.8, Rev. 5.4 (1994),
Metals – EPA 200.8 Page 7
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Section 11.4.3]
55 Is the average of the integrations used for data reporting? [EPA
Method 200.8, Rev. 5.4 (1994), Section 11.4.3]
56
Is the rinse blank used to flush the system between samples? [EPA
Method 200.8, Rev. 5.4 (1994), Section 10.5 and 11.4.6]

The rinse blank should be used to flush the
system between samples. Allow sufficient time
to remove traces of the previous sample or a
minimum of one minute (Section 4.1.5).
Samples should be aspirated for 30 seconds
prior to the collection of data.
57
For aqueous samples prepared by total recoverable procedure
(Section 11.2), are solution concentrations multiplied by the dilution
factor 1.25? [EPA Method 200.8, Rev. 5.4 (1994), Section 12.3]

If additional dilutions were made to any
samples or an aqueous sample was prepared
using the acid mixture procedure described in
Section 11.3, the appropriate factor should be
applied to the calculated sample
concentrations.
58
For total recoverable analytes in solid samples, are sample results
calculated and reported properly? [EPA Method 200.8, Rev. 5.4
(1994), Section 12.4]

Round the solution analyte concentrations
(µg/L in the analysis solution) as instructed in
Section 12.2. Multiply the µ/L concentrations in
the analysis solution by the factor 0.005 to
calculate the mg/L analyte concentration in the
100 mL extract solution. (If additional dilutions
were made to any samples, the appropriate
factor should be applied to calculate analyte
concentrations in the extract solution.) Report
the data up to three significant figures as
mg/kg dry-weight basis unless specified
otherwise by the program or data user.
Calculate the concentration using the
equation below:

Sample conc. (mg/kg) = C x V
Dry weight basis W

C = Concentration in the extract (mg/L)
V = Volume of extract (L, 100 mL = 0.1L)
W = Weight of sample aliquot extracted (g x
0.001 = kg)

Do not report analyte data below the estimated
solids MDL or an adjusted MDL because of
additional dilutions required to complete the
analysis.
59
Are data values corrected for instrument drift or sample matrix
induced interferences by the application of internal standardization?
[EPA Method 200.8, Rev. 5.4 (1994), Section 2.2 and 12.6]

Instrumental drift as well as suppressions or
enhancements of instrument response caused
by the sample matrix must be corrected for by
the use of internal standards. Corrections for
characterized spectral interferences should be
applied to the data. Chloride interference
corrections should be made on all samples,
regardless of the addition of hydrochloric acid,
as the chloride ion is a common constituent of
environmental samples.
QUALITY ASSURANCE
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EXPLANATION
60
Has an MDL been established for each element according to 40
CFR 136 Appendix B [a.k.a Procedure for the Determination of the
Method Detection Limit, Rev. 2]? [EPA Method 200.8, Rev. 5.4
(1994), Section 9.2.4]

Process a minimum of seven spiked samples
and seven method blank samples through all
steps of the method. The samples used for the
MDL must be prepared in at least three batches
on three separate calendar dates and analyzed
on three separate calendar dates.
61
Is ongoing MDL data being collected quarterly? [40 CFR 136
Appendix B] [Procedure for the Determination of the Method
Detection Limit, Rev. 2, (3) (a)]

During any quarter in which samples are being
analyzed, prepare and analyze a minimum of
two spiked samples on each instrument, in
separate batches, using the same spiking
concentration used in Section 2.
62
Are MDL values verified at least every 13 months according to the
ongoing MDL determination requirements and updated if necessary?
[40 CFR 136 Appendix B] [Procedure for the Determination of the
Method Detection Limit, Rev. 2, (4) (a)]

At least once every thirteen months, re-
calculate MDLs and MDLb from the collected
spiked samples and method blank results
using the equations in Section 2.
Metals – EPA 200.8 Page 8
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63
Is a known second source standard analyzed after initial calibration?
[15A NCAC 2H .0805 (a) (7) (H) (ii) and EPA Method 200.8, Rev. 5.4
(1994), Section 9.2.3]

Laboratories shall analyze one known second
source standard to verify the accuracy of
standard preparation if an initial calibration is
performed and in accordance with the
referenced method requirements thereafter.

The second source standard is equivalent to
the QCS in sections 7.8 and 9.2.3 of the
method.
64
What is the acceptance criterion of the second source standard?
[EPA Method 200.8, Rev. 5.4 (1994), Section 9.2.3]

ANSWER:

To verify the calibration standards the
determined mean concentration from three
analyses of the QCS must be within ±10% of
the stated QCS value. If the QCS is used for
determining acceptable on-going instrument
performance, analysis of the QCS prepared to
a concentration of 100 µg/L must be within
±10% of the stated value or within the
acceptance limits listed in Table 8, whichever
is the greater. (If the QCS is not within the
required limits, an immediate second analysis
of the QCS is recommended to confirm
unacceptable performance.) If the calibration
standards and/or acceptable instrument
performance cannot be verified, the source of
the problem must be identified and corrected
before either proceeding on with the initial
determination of method detection limits or
continuing with on-going analyses.
65
What corrective action does the laboratory take if the second source
standard does not meet the acceptance criterion? [EPA Method
200.8, Rev. 5.4 (1994), Section 9.2.3]

ANSWER:

(If the QCS is not within the required limits, an
immediate second analysis of the QCS is
recommended to confirm unacceptable
performance.) If the calibration standards
and/or acceptable instrument performance
cannot be verified, the source of the problem
must be identified and corrected before either
proceeding on with the initial determination of
method detection limits or continuing with on-
going analyses.
66 Is a lower reporting limit standard analyzed or back-calculated with
each analysis? [15A NCAC 2H .0805 (a) (7) (H)]
Laboratories shall analyze or back-calculate a
standard at the same concentration as the
lowest reporting concentration each day
samples are analyzed.
67
What is the acceptance criterion for the lower reporting limit standard?
[15A NCAC 2H .0805 (a) (7) (A)]

ANSWER:

Unless specified by the method or this Rule,
each laboratory shall establish performance
acceptance criteria for all quality control
analyses.
68
What corrective action does the laboratory take if the lower reporting
limit standard does not meet the acceptance criterion? [15A NCAC
2H .0805 (a) (7) (B)]

ANSWER:

If quality control results fall outside established
limits or show an analytical problem, the
laboratory shall identify the Root Cause of the
failure. The problem shall be resolved through
corrective action, the corrective action process
documented, and any samples involved shall
be reanalyzed, if possible.
Recalibrate/re-verify the curve.
69
Is at least one Laboratory Reagent Blank analyzed with each batch of
20 or fewer of samples of the same matrix? [EPA Method 200.8, Rev.
5.4 (1994), Section 9.3.1]

The LRB must contain all the reagents in the
same volumes as used in processing the
samples. The LRB must be carried through the
same entire preparation scheme as the
samples including digestion, when applicable.
If the direct addition procedure (Method A,
Section 10.3) is being used, add internal
standards to the solution after preparation is
complete.
70
What is the acceptance criterion of the LRB? [15A NCAC 2H .0805
(a) (7) (H) (i) or EPA Method 200.8, Rev. 5.4 (1994), Section 9.3.1]

ANSWER:

Rule: The concentration of reagent, method,
and calibration blanks shall not exceed 50
percent of the lowest reporting concentration
or as otherwise specified by the reference
method.

Metals – EPA 200.8 Page 9
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Method: Must not exceed 10% or more of the
analyte level determined for a sample or 2.2
times the analyte MDL, whichever is greater.

71
What corrective action does the laboratory take if the LRB does not
meet the acceptance criterion? [15A NCAC 2H .0805 (a) (7) (B)]

ANSWER:

If quality control results fall outside established
limits or show an analytical problem, the
laboratory shall identify the Root Cause of the
failure. The problem shall be resolved through
corrective action, the corrective action process
documented, and any samples involved shall
be reanalyzed, if possible.
Recalibrate/re-verify the curve.
72
Is at least one Laboratory Fortified Blank (LFB) analyzed with each
batch of samples? [EPA Method 200.8, Rev. 5.4 (1994), Section
9.3.2]

To an aliquot of LRB, add aliquots from
multielement stock standards A and B (Section
7.4) to prepared the LFB. Depending on the
sensitivity of the instrument, the fortified
concentration used should range from 40-100
µg/L for each analyte, except selenium and
mercury. For selenium the concentration
should range from 200-500 µg/L, while the
concentration range mercury should be limited
to 2-5 µg/L. The LFB must be carried through
the same entire preparation scheme as the
samples including sample digestion, when
applicable. If the direct addition procedure
(Method A, Section 10.3) is being used, add
internal standards to this solution after
preparation has been completed.
73
What is the acceptance criterion of the LFB? [EPA Method 200.8,
Rev. 5.4 (1994), Section 9.3.2]

ANSWER:

If the recovery of any analyte falls outside the
required control limits of 85-115%, that analyte
is judged out of control, and the source of the
problem should be identified and resolved
before continuing analyses.
74
What corrective action does the laboratory take if the LFB does not
meet the acceptance criterion? [15A NCAC 2H .0805 (a) (7) (B)]

ANSWER:

If quality control results fall outside established
limits or show an analytical problem, the
laboratory shall identify the Root Cause of the
failure. The problem shall be resolved through
corrective action, the corrective action process
documented, and any samples involved shall
be reanalyzed, if possible.
Recalibrate/re-verify the curve.
75
To verify calibration, are the calibration blank and a calibration
standard analyzed immediately following each calibration routine, after
every ten analyses and at the end of the sample run? [EPA Method
200.8, Rev. 5.4 (1994), Section 9.3.4]

Per Ray Terhune with EPA Region IV, it is
acceptable to analyze only one calibration
point and the calibration blank after every ten
samples and at the end of the sample run.
76
What is the acceptance criterion of the calibration blank? [15A NCAC
2H .0805 (a) (7) (H) (i)]

ANSWER:

The concentration of reagent, method, and
calibration blanks shall not exceed 50 percent
of the lowest reporting concentration or as
otherwise specified by the reference method.

77
What corrective action does the laboratory take if the calibration blank
does not meet the acceptance criterion? [15A NCAC 2H .0805 (a) (7)
(B)]

ANSWER:

If quality control results fall outside established
limits or show an analytical problem, the
laboratory shall identify the Root Cause of the
failure. The problem shall be resolved through
corrective action, the corrective action process
documented, and any samples involved shall
be reanalyzed, if possible. Recalibrate/re-verify
the curve.
78
What is the acceptance criterion of the calibration standard? [EPA
Method 200.8, Rev. 5.4 (1994), Section 9.3.4] [15A NCAC 2H .0805
(e) (5)]

ANSWER:

If the calibration standard exceeds ±10%, the
instrument must be recalibrated and verified. If
that failing calibration standard exceeded
±15%, the previous 10 samples, spikes and
duplicates MUST be reanalyzed after the
recalibration. If the failing CCV was between ±
10-15%R, then the samples do NOT need to
be reanalyzed. However, per our Rules, 15A
NCAC 02H .0805 (e) (5), the samples that
were not reanalyzed MUST be qualified if
reported.
Metals – EPA 200.8 Page 10
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79
Is a Laboratory Fortified Matrix (LFM) analyzed at minimum frequency
of 10% of samples? [EPA Method 200.8, Rev. 5.4 (1994), Section
9.4.2]

For water samples, the added analyte
concentration must be the same as that used
in the laboratory fortified blank (Section 7.9).
For solid samples, the concentration added
should be 100 mg/kg equivalent (200 μg/L in
the analysis solution) except silver which
should be limited to 50 mg/kg (Section 1.8).
Over time, samples from all routine sample
sources should be fortified.
80
How is the LFM prepared? [NC WW/GW LCB Matrix Policy and
Technical Assistance]

ANSWER:

Volume of spiking solution must not exceed
5% of total volume.
81
If the volume of spike solution added to the sample is greater than
1% of the total volume, is the recovery calculation adjusted? [NC
WW/GW LCB Policy]

It is preferable that the spike solution
constitutes < 1% of the total MS volume so
that the MS can be considered a whole volume
sample with no adjustment (i.e., volume
correction) by calculation necessary. If the
spike solution volume constitutes >1% of the
total sample volume, the sample concentration
must be adjusted by calculation.
82
What is the acceptance criterion of the LFM? [EPA Method 200.8,
Rev. 5.4 (1994), Section 9.4.3] [15A NCAC 2H .0805 (a) (7) (A)]

ANSWER:

Calculate the percent recovery for each
analyte, corrected for background
concentrations measured in the unfortified
sample, and compare these values to the
designated LFM recovery range of 70-130%.
83
How are internal standards responses evaluated? [EPA Method
200.8, Rev. 5.4 (1994), Section 9.4.5]

ANSWER:

The analyst is expected to monitor the
responses from the internal standards
throughout the sample set being analyzed.
Ratios of the internal standards responses
against each other should also be monitored
routinely. This information may be used to
detect potential problems caused by mass
dependent drift, errors incurred in adding the
internal standards or increases in the
concentrations of individual internal standards
caused by background contributions from the
sample. The absolute response of any one
internal standard must not deviate more than
60-125% of the original response in the
calibration blank. If deviations greater than
these are observed, flush the instrument with
the rinse blank and monitor the responses in
the calibration blank. If the responses of the
internal standards are now within the limit, take
a fresh aliquot of the sample, dilute by a
further factor of two, add the internal standards
and reanalyze. If after flushing the response of
the internal standards in the calibration blank
are out of limits, terminate the analysis and
determine the cause of the drift. Possible
causes of drift may be a partially blocked
sampling cone or a change in the tuning
condition of the instrument.
84 Are 5% of the samples analyzed in duplicate? [15A NCAC 2H .0805
(a) (7) (C)]
Except where otherwise specified in an
analytical method, laboratories shall analyze
five percent of all samples in duplicate to
document precision. Laboratories analyzing
fewer than 20 samples per month shall
analyze one duplicate during each month that
samples are analyzed.
Analysis of a LFM duplicate may also fulfill this
requirement.
85
What is the duplicate acceptance criterion? [15A NCAC 2H .0805 (a)
(7) (A)]

ANSWER:

Unless specified by the method or this Rule,
each laboratory shall establish performance
acceptance criteria for all quality control
analyses.

Metals – EPA 200.8 Page 11
Revised 03/09/2022
Limits set by the laboratory
86
What corrective action does the laboratory take if duplicates do not
meet the acceptance criterion? [15A NCAC 2H .0805 (a) (7) (B)]

ANSWER:

If quality control results fall outside established
limits or show an analytical problem, the
laboratory shall identify the Root Cause of the
failure. The problem shall be resolved through
corrective action, the corrective action process
documented, and any samples involved shall
be reanalyzed, if possible.
87
Is the data qualified on the Discharge Monitoring Report (DMR) or
client report if Quality Control (QC) requirements are not met? [15A
NCAC 2H .0805 (a) (7) (B)]

If the sample cannot be reanalyzed, or if the
quality control results continue to fall outside
established limits or show an analytical
problem, the results shall be qualified as such.

If data qualifiers are used to qualify samples
not meeting QC requirements, the data may
not be useable for the intended purposes. It is
the responsibility of the laboratory to provide
the client or end-user of the data with sufficient
information to determine the usability of the
qualified data.

Additional Comments:
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Inspector: ______________________________________________________Date:_________________________________________