&EPA
United States Environmental Protection Agency
Office of Water Regulations and Standards
Industrial Technology Division
Office of Water DRAFT September 1989
Method 1620: Metals by Inductively
Coupled Plasma Atomic Emission
Spectroscopy and Atomic Absorption
Spectroscopy
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3o<.~7
Introduction
Method 1620 was developed by the Industrial Technology
Division (ITD) within the United States Environmental
Protection Agency's (USEPA) Office of Uater Regulations and
Standards (OURS) to provide improved precision and accuracy of
analysis of pollutants in aqueous and solid matrices. The ITD
is responsible for development and promulgation of nationwide
standards setting limits on pollutant levels in industrial
discharges.
Method 1620 includes inductively coupled plasma atomic
emission (ICP) spectroscopy, graphite furnace atomic
absorption (GFAA) spectroscopy, and cold vapor atomic
absorption (CVAA) spectroscopy techniques for analysis of 27
specified metals. The method also includes an ICP technique
for use as a semiquantitative screen for 42 specified
elements.
Questions concerning the method or its application should be
addressed to:
U. A. Telliard
USEPA
Office of Water Regulations and Standards
401 M Street SU
Washington, DC 20460
202/382-7131
OR
USEPA OURS
Sample Control Center
P.O. Box 1407
Alexandria, Virginia 22313
703/557-5040
Publication date: September 1989 DRAFT
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Method 1620 DRAFT September 1989
Metals by Inductively Coupled Plasma Atomic Emission
Spectroscopy and Atomic Absorption Spectroscopy
1 SCOPE AND APPLICATION
1.1 This method is designed to meet the survey
requirements of the USEPA ITD. It is used
to determine specified elements associated
with the Clean Water Act (as amended
1987); the Resource Conservation and
Recovery Act (as amended 1986); and the
Comprehensive Environmental Response,
Compensation and Liability Act (as amended
1986); and other elements amenable to
analysis by inductively coupled plasma
(ICP) atomic emission spectroscopy,
graphite furnace atomic absorption (GFAA)
spectroscopy, and cold vapor atomic
absorption (CVAA) spectroscopy.
1.2 The method is a consolidation of USEPA
Methods 200.7 (ICP for trace elements),
204.2 (Sb), 206.2 (As), 239.2 (Pb), 270.2
(Se), 279.2 (Tl), 245.5 (Hg), 245.1 (Hg),
and 245.2 (Hg). The method is used for
analysis of trace elements by ICP atomic
emission spectroscopy and GFAA
spectroscopy, for analysis of mercury by
CVAA spectroscopy, and as a semi-
quantitative ICP screen for specified
elements.
1.3 The elements listed in Tables 1, 2 and 4
may be determined in waters, soils,
sediments, and sludges by this method.
1.4 The recommended wavelengths and instrument
detection limits of this method are shown
In Tables 1-2. Actual sample detection
limits are dependent on the sample matrix
rather than instrumental limitations. The
levels given typify the mininun quantities
that can be detected with no interferences
present. Table 2 also lists the optimun
concentration range.
1.5 Table 4 lists the wavelengths and lower
threshold limits (LTL) for the 42 elements
for semiquantitative ICP screen.
1.6 The ICP and AA portions of this method are
for use only by analysts experienced with
the instrumentation or under the close
supervision of such qualified persons.
Each laboratory that uses this method must
demonstrate the ability to generate
acceptable results using the procedure in
Section 8.2.
2 SUMMARY OF METHOO
2.1 ICP-Atomic Emission Spectrometric Method
for Analysis of Water and Soil/Sediment
Samples
2.1.1 The method describes a technique for the
simultaneous or sequential multi-element
determination of trace elements in
solution. The basis of the method is the
measurement of atomic emission by an
optical spectroscopic technique. Samples
are nebulized and the aerosol that is
produced is transported to the plasma
torch where excitation occurs.
Characteristic atomic-line emission
spectra are produced by a radio-frequency
inductively coupled plasma (ICP). The
spectra are dispersed by a grating
spectrometer and the intensities of the
lines are monitored by photomultiplier
tubes. The photocurrents from the
photomultiplier tubes are processed and
controlled by a computer system.
2.1.2 A background correction technique is
required to compensate for variable
background contribution to the
determination of trace elements.
Background must be measured adjacent to
analyte lines during sample analysis. The
position selected for the background
intensity measurement, on either or both
sides of the analytical line, will be
determined by the complexity of the
spectrin adjacent to the analyte line.
The position used must be free of spectral
interference and reflect the same change
in background intensity as occurs at the
analyte wavelength measured. Background
correction is not required in cases of
line broadening where a background
correction measurement would actually
degrade the analytical result. The
possibility of additional interferences
named in Section 3.1.1 (and tests for
their presence as described in Section
3.1.2) should also be recognized and
appropriate corrections made.
2.1.3 Dissolved elements (those which will pass
through a 0.45 um membrane filter) are
determined in samples that have been
filtered and acidified. Appropriate steps
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must be taken in all analyses to ensure
that potential interferences are taken
into account. This is especially true
when dissolved solids exceed 1500 mg/L.
(See Section 3.1.)
2.1.4 Total elements (total concentration in an
wfiltered sample) are determined after
appropriate digestion procedures are
performed. Since digestion techniques
increase the dissolved solids content of
the samples, appropriate steps must be
taken to correct for the effects of
potential interferences. (See Section
3.1.)
2.1.5 Table 1 lists elements that may be
analyzed by this method along with
recommended wavelengths and typical
estimated instrumental detection limits
using conventional pneumatic nebulization.
Actual working detection limits are sample
dependent and as the sample matrix varies,
these concentrations may also vary.
Instruments with ultrasonic nebulization
may be able to achieve lower instrumental
detection limits.
2.1.6 Because of the differences between various
makes and models of satisfactory
instruments, no detailed instrumental
operating instructions can be provided.
Instead, the analyst is referred to the
instructions provided by the manufacturer
of the particular instrunent.
2.1.7 The semiquantitative screening procedure
requires a sequential ICP instrunent (2
channel minimum) interfaced with a
computerized data system capable of the
short sampling times and the narrow survey
windows necessary to perform a
semiquantitative ICP screen.
2.1.7.1 Table 4 lists the wavelengths to be used
in the semiquantitative ICP screen for
each analyte, and the lower threshold
limits (LTL). The LTL for each analyte is
highly dependent upon sample matrix and
subject to change on a sample-by-sample
basis.
2.1.8 Sludge samples having less than 1X solids
are treated as water samples. Those
having between IX to 30X solids should be
diluted to less than 1X solids, and then
treated as water sanples. Sludge samples
having greater than 30X solids should be
treated as soil samples.
2.2 GFAA Spectroscopy for Analysis of Water
and Soil/Sediment Samples
2.2.1 This method describes a technique for
multi-element determination of trace
elements in solution. A few microliters
of the sample are first evaporated at a
low tenperature (sufficient heat to remove
the solvent from the sample) and then
ashed at a higher tenperature on an
electrically heated surface of carbon,
tantalun, or other conducting material.
The conductor can be formed as a hollow
tube, a strip, a rod, a boat, or a trough.
After ashing, the current is rapidly
increased to several hundred amperes,
which causes the temperature to rise to
2000-3000 °C; atomization of the sample
occurs in a period of a few milliseconds
to seconds. The absorption or
fluorescence of the atomized particles can
then be measured in the region above the
heated conductor. At the wavelength at
which absorbance (or fluorescence) occurs,
the detector output rises to a maximum
after a few seconds of ignition, followed
by a rapid decay back to zero as the
atomization products escape into the
surroundings. The change is rapid enough
to require a high speed recorder.
2.2.2 The matrix interference problem is one of
the major causes of poor accuracy
encountered with this method. It has been
found empirically that some of the sample
matrix effects and poor reproducibility
associated with graphite furnace
atomization can be alleviated by reducing
the natural porosity of the graphite tube.
A background correction technique is
required to compensate for variable
background contribution to the
determination of trace elements.
2.2.3 Table 2 lists elements that may be
analyzed by GFAA along with recommended
wavelengths, estimated instrumental
detection limits, and optimun concen-
tration range. Table 3 lists recommended
instrumental operating parameters.
2.2.4 For treatment of sludge samples, see
Section 2.1.8.
2.3 Cold Vapor AA (CVAA) Techniques for
Analysis of Mercury
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2.3.1 Manual CVAA Technique for Analysis of
Mercury in Water Samples
2.3.1.1 The ftameless AA procedure is a method
based on the absorption of radiation at
253.7 ran by mercury vapor. Mercury
compounds are oxidized and the mercury is
reduced to the elemental state and aerated
from solution in a closed system. The
mercury vapor passes through a cell
positioned in the light path of an atomic
absorption spectrophotometer. Absorbance
(peak height) is measured as a function of
mercury concentration.
2.3.1.2 In addition to inorganic forms of mercury,
organic mercurials may also be present.
These organo-mercury compounds will not
respond to the cold vapor atomic
absorption technique unless they are first
broken down and converted to mercuric
ions. Potassium permanganate oxidizes
many of these compounds, but recent
studies have shown that a number of
organic mercurials, including phenyl
mercuric acetate and methyl mercuric
chloride, are only partially oxidized by
this reagent. Potassiun persulfate has
been found to give approximately 100%
recovery when used as the oxidant uith
these compounds. Therefore, a persulfate
oxidation step following the addition of
the permanganate has been included to
ensure that organo-mercury compounds, if
present, will be oxidized to the mercuric
ion before measurement. A heating step is
required for methyl mercuric chloride when
present in or spiked into a natural
system. The heating step is not necessary
for distilled water.
2.3.1.3 The working range of the method may be
varied through instrument and/or recorder
expansion. Using a 100 mL sample, a
detection limit of 0.2 ug Hg/L can be
achieved (see Section 7.2.3).
2.3.1.4 For treatment of sludge samples, see
Section 2.1.8.
2.3.2 Automated CVAA Technique for Analysis of
Mercury in Uater Samples
2.3.2.1 See Section 2.3.1.1.
2.3.2.2 See Section 2.3.1.2.
2.3.2.3 The working range of the method is 0.2 to
20.0 ug Hg/L.
2.3.2.4 For treatment of sludge samples, see
Section 2.1.8.
2.3.3 Manual CVAA Technique for Analysis of
Mercury in Soil/Sediment Samples
2.3.3.1 A weighed portion of the sample is
digested in acid for 2 minutes at 95 °C,
followed by oxidation with potassiun
permanganate and potassiun persulfate.
Mercury in the digested sample is then
measured by the conventional cold vapor
technique. An alternate digestion
involving the use of an autoclave is
described in Section 10.5.2.
2.3.3.2
2.3.3.3
3.1
The working range of the method is 0.2 to
5 ug/g. The range may be extended above
or below the normal range by increasing or
decreasing sairple size or through
instrument and/or recorder expansion.
For treatment of sludge samples, see
Section 2.1.8.
INTERFERENCES
Interferences Observed with
Emission Spectrometric Method
ICP-Atomic
3.1.1 Three types of interference effects may
contribute to inaccuracies in the
determination of trace elements:
spectral, physical, and chemical. These
are summarized as follows.
3.1.1.1 Spectral interferences
3.1.1.1.1 Spectral interferences can be categorized
as: 1) overlap of a spectral line from
another element, 2) unresolved overlap of
molecular band spectra, 3) background
contribution from continuous or
recombination phenomena, and 4) background
contribution from stray light from the
line emission of high concentration
elements. The first of these effects can
be compensated for by utilizing a computer
correction of the raw data, requiring the
monitoring and measurement of the
interfering element. The second effect
may require selection of an alternate
wavelength. The third and fourth effects
can usually be compensated for by a
background correction adjacent to the
analyte line. In addition, users of
simultaneous multi-element instrumentation
must assume the responsibility of
verifying the absence of spectral
interference from an element that could
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occur in a sample but for which there is
no channel in the instrument array.
3.1.1.1.2 Listed in Table 5 are some interference
effects for the recommended wavelengths
given in Table 1. The data in Table 5 are
intended for use only as a rudimentary
guide for the indication of potential
spectral interferences. For this purpose,
linear relations between concentration and
intensity for the analytes and the
interferents can be assuned. The
Interference information, which was
collected at the Ames Laboratory (USDOE,
Iowa State University, Ames, Iowa 50011)
is expressed as analyte concentration
equivalents (i.e., false analyte
concentrations) arising from 100 mg/L of
the interferent element.
3.1.1.1.3 The suggested use of this information is
as follows: Assume that arsenic (at
193.696 nm) is to be determined in a
sample containing approximately 10 mg/L of
aluminum. According to Table 5, 100 mg/L
of aluninum would yield a false signal for
arsenic equivalent to approximately 1.3
mg/L. Therefore, 10 mg/L of aluninun
would result in a false signal for arsenic
equivalent to approximately 0.13 mg/L.
The reader is cautioned that other
analytical systems may exhibit somewhat
different levels of interference than
those shown in Table 5, and that the
interference effects must be evaluated for
each individual system. Only those
interferents listed were investigated, and
the blank spaces in Table 5 indicate that
measurable interferences were not observed
from the interferent concentrations listed
in Table 6. Generally, interferences were
discernible if they produced peaks or
background shifts corresponding to 2-5% of
the peak heights generated by the analyte
concentrations also listed in Table 6.
3.1.1.1.4 At present, information on the listed
silver and potassiun wavelengths are not
available, but it has been reported that
second order energy from the magnesiun
383.231 nm wavelength interferes with the
listed potassium line at 766.491 nm.
3.1.1.2 Physical interferences
3.1.1.2.1 Physical interferences are generally
considered to be effects associated with
the sample nebulization and transport
processes. Changes in properties such as
viscosity and surface tension can cause
significant inaccuracies, especially in
samples which may contain high dissolved
solids and/or acid concentrations. The
use of a peristaltic pump may lessen these
interferences. If these types of
interferences are operative, they must be
reduced by dilution of the sample and/or
utilization of standard addition
techniques. Another problem which can
occur from high dissolved solids is salt
buildup at the tip of the nebulizer. This
affects aerosol flow rate and causes
instrunental drift. Internal standards
may also be used to compensate for
physical interferences.
3.1.1.2.2 Uetting the argon prior to nebulization,
the use of a tip washer, or sample
dilution techniques have been used to
control this problem. Also, it has been
reported that better control of the argon
flow rate improves instrument performance.
This is accomplished with the use of mass
flow controllers. Nebulizers specifically
designed for use with solutions containing
high concentration of dissolved solids may
be used.
3.1.1.3 Chemical interferences -- These interfer-
ences are characterized by molecular
compound formation, ionization effects,
and solute vaporization effects. Normally
these effects are not pronounced with the
ICP technique. However, if observed, they
can be minimized by careful selection of
operating conditions (that is, incident
power, observation position, and so
forth), by buffering of the sample, by
matrix matching, and by standard addition
procedures. These types of interferences
can be highly dependent on matrix type and
the specific analyte element.
3.1.2 The ICP Serial Dilution Analysis must be
performed on 10% of the samples, or at
least once for each set or Episode of
samples. Samples identified as field
blanks cannot be used for serial dilution
analysis. If the analyte concentration is
- sufficiently high (minimally a factor of
50 above the instrunental detection limit
in the original sample), the serial
dilution (a five-fold dilution) must then
agree within 10% of the original
determination after correction for
dilution. If the dilution analysis for
one or more analytes is not within 10%, a
chemical or physical interference effect
must be suspected, and the data for all
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affected analytes in the samples
associated with that serial dilution must
be flagged.
3.2 Interferences Observed with
Spectroscopic Method
GFAA
3.2.1 Interferences of three types are
encountered in atonic absorption methods
using electrothermal atomization:
spectral, chemical, and physical. These
interferences are summarized as follows.
3.2.1.1 Spectral interferences
3.2.1.1.1 Spectral interferences arise when the
absorption of an interfering species
either overlaps or lies close to the
analyte absorption. Then resolution by
the monochromator becomes impossible.
This effect can be compensated for by
monitoring the presence of the interfering
element.
3.2.1.1.2 Spectral interferences could also arise
because of the presence of combustion
products that exhibit broad band
absorption or particulate products that
scatter radiation. This problem can also
originate in the sample matrix itself. If
the source of interference is known, an
excess of the interfering substance can be
added to both the sanple and standards.
Provided that the excess is large with
respect to the concentration from the
sample matrix, the contribution from the
sample matrix will become insignificant.
3.2.1.1.3 The matrix interference problem is greatly
exacerbated with electrothermal atomiza-
tion; this is one of the major causes for
poor accuracy. Scattering by incompletely
decomposed organic particles also occurs
commonly. As a consequence, the need for
background correction techniques is
encountered with electrothermal atomiza-
tion. The use of Zeeman or Smith-Hieftje
background correction techniques is
rec amended.
3.2.1.2 Chemical interferences are more common
than spectral ones. Their effects can be
minimized by a suitable choice of
operating conditions. These interferences
can be categorized as: 1) formation of
compounds of low volatility which reduces
the rate at which the sample is atomized,
2)ionization of atoms and molecules, and
3) solute vaporization effects^ These
interferences can be minimized by varying
the temperature and addition of ionization
suppressor or by standard addition
technique. These interferences can be
highly dependent on the matrix type and
the specific analyte element.
3.2.1.3 Physical interferences are pronounced with
samples containing high dissolved solids
and/or acid concentration resulting in
change in viscosity and surface tension.
If these types of interferences are
operative, they can be reduced by dilution
of the sample.
3.2.2 Possible interferences observed during
analysis of trace elements by GFAA
spectroscopic methods and certain
recommended instrumental parameters -- All
furnace elements must be analyzed by
method of standard addition (Section
8.15). The use of background correction
is also required for all of these
elements.
3.2.2.1 Antimony
3.2.2.1.1 Nitrogen may also be used as the purge
gas.
3.2.2.1.2 If chloride concentration presents a
matrix problem or causes a loss previous
to atomization, add an excess 5 mg of
ainnoniijn nitrate to the furnace and ash
using a ramp accessory or with incremental
steps until the recommended ashing
temperature is reached.
3.2.2.2 Arsenic
3.2.2.2.1 The use of Zeeman or Smith-Hieftje
background correction is required.
Background correction made by the
deuterium arc method does not adequately
compensate for high levels of certain
interferents
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3.2.2.4 Cadniun
3.2.2.4.1 Contamination from the work area is
critical in cadmiun analysis. Use pipette
tips which are free of cadnium.
3.2.2.5 Chromiun
3.2.2.5.1 Hydrogen peroxide fs added to the
acidified solution to convert all chromium
to the trivalent state. Calcium is added
to the solution at a level of at least 200
mg/L where its suppressive effect becomes
constant up to 1000 mg/L.
3.2.2.5.2 Nitrogen should not be used as a purge gas
because of possible CN band interference.
3.2.2.5.3 Pipette tips have been reported to be a
possible source of contamination.
3.2.2.6 Lead
3.2.2.6.1 Greater sensitivity can be achieved using
the 217.0 nm line, but the optimun
concentration range is reduced. The use
of a lead Electrodeless Discharge Lamp at
this lower wavelength has been found to be
advantageous. Also, a lower atotnization
temperature (2400 °C) may be preferred.
3.2.2.6.2 To suppress sulfate interference (up to
1500 ppbi) lanthanun nitrate is added to
both samples and calibration standards.
(Atomic Absorption Newsletter Vol. 15, No.
3, p. 71, May-June 1976).
3.2.2.6.3 Since glassware contamination is a severe
problem in lead analysis, all glassware
should be cleaned immediately prior to
use, and once cleaned, should not be open
to the atmosphere except when necessary.
3.2.2.7 Seleniun
3.2.2.7.1 The use of Zeeman or Smith-Hieftje
background correction is required.
Background correction made by the
deuteriun arc method does not adequately
compensate for high levels of certain
interferents (i.e., Al, Fe). If
conditions occur where significant
interference is suspected, the laboratory
must switch to an alternate wavelength or
take other appropriate actions to
compensate for the interference effects.
3.2.2.7.2 Selenium analysis suffers interference
from chlorides (>800 mg/L) and sulfate
(>200 mg/L). For the analysis of
industrial effluents and samples with
concentrations of sulfate from 200 to 2000
mg/L, both samples and standards should be
prepared to contain 1% nickel.
3.2.2.7.3 The use of an electrodeless discharge lamp
(EDL) for the light source is recommended.
3.2.2.8 Thallium
3.2.2.8.1 Nitrogen may also be used as the purge
gas.
3.3 Interferences Observed with Cold Vapor AA
(CVAA) Techniques for Analysis of Hercury
3.3.1 Manual CVAA technique for analysis of
mercury in water
3.3.1.1 Possible interference from sulfide is
eliminated by the addition of potassium
permanganate. Concentrations as high as
20 mg/l of sulfide as sodium sulfide do
not interfere with the recovery of added
inorganic mercury from distilled water.
3.3.1.2 Copper may interfere in the analysis of
mercury; however, copper concentrations as
high as 10 mg/L had no effect on recovery
of mercury from spiked samples.
3.3.1.3 Seawaters, brines and industrial effluents
high in chlorides require additional
permanganate (as much as 25 mL). During
the oxidation step, chlorides are
converted to free chlorine which will also
absorb radiation of 253 nm. Care must be
taken to assure that free chlorine is
absent before the mercury is reduced and
swept into the cell. This may be
accomplished by using an excess of
hydroxylamine sulfate reagent (25 mL).
Both inorganic and organic mercury spikes
have been quantitatively recovered from
the seawater using this technique.
3.3.1.4 Uhile the possibility of absorption from
certain organic substances actually being
present in the sample does exist, EPA
laboratories have not encountered such
samples to date. This is mentioned only
to caution the analyst of the possibility.
3.3.2 Automated CVAA technique for analysis of
mercury in water
3.3.2.1 Some seawaters and wastewaters high in
chlorides have shown a positive
interference, probably due to the
formation of free chlorine. (See Section
3.3.1.3.)
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3.3.2.2 Formation of a heavy precipitate, in some
wastewaters and effluents, has been
reported upon addition of concentrated
sulfuric acid. If this is encountered,
the problem sample cannot be analyzed by
this method.
3.3.2.3 If total mercury values are to be
reported, samples containing solids must
be blended and then mixed while being
sampled.
3.3.3 Manual CVAA technique for analysis of
mercury in soil
3.3.3.1 The same types of interferences that may
occur in water samples are also possible
with soils/sediments, i.e., sulfides, high
copper, high chlorides, etc.
3.3.3.2 Samples containing high concentrations of
oxidizable organic materials, as evidenced
by high chemical oxygen demand values, may
not be completely oxidized by this
procedure. When this occurs, the recovery
of organic mercury will be low. The
problem can be eliminated by reducing the
weight of the original sample or by
increasing the amount of potassiun
persulfate (and consequently stannous
chloride) used in the digestion.
3.3.3.3 Volatile materials which absorb at 253.7
nm will cause a positive interference. In
order to remove any interfering volatile
material, purge the dead air space in the
BOO bottle before the addition of stannous
sulfate.'
4 SAFETY
4.1 The toxicity or carcinogenicity of each
reagent used in these methods has not been
precisely defined; however, each chemical
compound should be treated as a potential
health hazard. The laboratory is
responsible for maintaining a current
awareness file of OSHA regulations
regarding the safe handling of the
chemicals specified in this method. A
reference file of material handling data
sheets should be made available to all
personnel involved in the chemical
analysis.
5 APPARATUS AND EQUIPMENT
5.1 ICP-Atomic Emission Spectrometer
5.1.1 Sequential ICP instrunents (2 channel
minimum) interfaced with a computerized
data system capable of short sanpling
times and narrow survey windows necessary
for the semiquantitative ICP screening
procedure and facility for background
correction.
5.1.2 Radio frequency generator.
5.1.3 Argon gas supply, welding grade or better.
5.2 GFAA Spectrometer.
5.2.1 Computer-controlled atomic absorption
spectrometer with background correction.
5.2.2 Argon gas supply, welding grade or better.
5.3 For ICP-Atomic Emission and GFAA, the
following is also required.
5.3.1 250 mL beaker or other appropriate vessel.
5.3.2 Watch glasses.
5.3.3 Thermometer that covers range of 0 - 200
°C.
5.3.4 Whatman No. 42 filter paper or equivalent.
5.4 Apparatus for manual CVAA mercury analysis
in water
5.4.1 Atomic absorption spectrophotometer: Any
atomic absorption unit having an open
sample presentation area in which to mount
the absorption cell is suitable.
Instrument settings recommended by the
particular manufacturer should be
followed. NOTE: Instruments designed
specifically for the measurement of
mercury using the cold vapor technique are
commercially available and may be
substituted for the atomic absorption
spectrophotometer.
5.4.2 Mercury hollow cathode lamp: Uestinghouse
WL-22847, argon-filled, or equivalent.
5.4.3 Recorder: Any multirange variable speed
recorder that is compatible with the UV
detection system is suitable.
5.4.4 Absorption cell: Standard spectrophoto-
meter cells 10 cm long, having quartz end
windows may be used. Suitable cells may
be constructed from plexiglass tubing, 1"
O.D. X 4-1/2". The ends are ground
perpendicular to the longitudinal axis and
quartz windows (1" diameter X 1/16"
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thickness) are cemented in place. The
cell is strapped to a burner for support
and aligned in the light bean by use of
two 2U x 2" cards. One-inch diameter
holes are cut in the middle of each card;
the cards are then placed over each end of
the cell. The cell is then positioned and
adjusted vertically and horizontally to
find the maximum transmittance.
5.4.5 Air pimp: Any peristaltic punp capable of
delivering 1 liter of air per minute may
be used. A Masterflex punp with
electronic speed control has been found to
be satisfactory.
5.4.6 Flowmeter: Capable of measuring an air
flow of 1 liter per minute.
5.5 Apparatus for automated CVAA mercury
analysis in water
5.5.1 Technicon auto analyzer or equivalent
instrumentation consisting of:
5.5.1.1 Sampler II with provision for sample
mixing.
5.5.1.2 Manifold.
5.5.1.3 Proportioning pump II or III.
5.5.1.4 High temperature heating bath with two
distillation coils (Technicon Part #116-
0163) in series.
5.5.2 Vapor-liquid separator (Figure 2).
5.4.7 Aeration tubing: A straight glass fit
having a coarse porosity. Tygon tubing is
used for passage of the mercury vapor from
the sample bottle to the absorption cell
and return.
5.4.8 Drying tube: 6" X 3/4" diameter tube
containing 20 g of magnesium perchlorate.
The apparatus is assembled as shown in
Figure 1. NOTE: In place of the
magnesium perchlorate drying tube, a small
reading lamp with 60U bulb may be used to
prevent condensation of moisture inside
the cell. The lamp is positioned to shine
on the absorption cell maintaining the air
temperature in the cell about 10 °C above
aobient.
¦ SOLUTION
OUT
FIGURE 2 Vapor Liquid Separator
SAMPLE SOLUTION
IN BOO BOTTLE
FIGURE 1 Apparatus for Flameless Mercury
Determination
5.5.3 Absorption cell, 100 mm long, 10 mm
diameter with quartz windows.
5.5.4 Atonic absorption spectrophotometer (see
Section 5.4.1).
5.5.5 Mercury hollow cathode lamp (see Section
5.4.2).
5.5.6 Recorder (see Section 5.4.3).
5.6 Apparatus for manual CVAA mercury analysis
in soil/sediment
5.6.1 Atomic Absorption Spectrophotometer (see
Section 5.4.1).
8
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5.6.2 Mercury Hollow Cathode Lanp (see Section
5.4.2).
5.6.3 Recorder (see Section 5.4.3).
5.6.4 Absorption Cell (see Section 5.4.4).
5.6.5 Air Pump (see Section 5.4.5).
5.6.6 Flowmeter (See Section 5.4.6.).
5.6.7 Aeration tubing (see Section 5.4.7).
5.6.8 Drying tube: 6" X 3/4" diameter tube
containing 20 g of magnesium perchlorate
(see NOTE in Section 5.4.8).
6 REAGENTS AND STANDARDS
6.1 ICP-Atomic Absorption Spectrometry
Quantitative screening of 21 elements
6.1.1 Acids used in the preparation of standards
and for sample processing must be ultra-
high purity grade or equivalent.
Redistilled acids are acceptable.
6.1.1.1 Acetic acid, conc. (sp gr 1.06).
6.1.1.2 Hydrochloric acid, conc. (sp gr 1.19).
6.1.1.3 Hydrochloric acid, (1+1): Add 500 nl
conc. HCl (sp gr 1.19) to 400 mL
deionized distilled water and dilute to 1
liter.
6.1.1.4 Nitric acid, conc. (sp gr 1.41).
6.1.1.5 Nitric acid, (1+1): Add 500 mL conc.
HNOj (sp gr 1.41) to 400 mL de ionized
distilled water and dilute to 1 liter.
6.1.2 Deionized distilled water: Prepare by
passing distilled water through a mixed
bed of cation and anion exchange resins.
Use deionized distilled water for the
preparation of all reagents, calibration
standards and as dilution water. The
purity of this water must be equivalent to
ASTM Type 11 reagent water of
Specification D 1193.
6.1.3 Standard stock solutions may be purchased
or prepared from ultra high purity grade
chemicals or metals. All salts must be
dried for one hour at 105 °C unless
otherwise specified. (CAUTION: Many
metal salts are extremely toxic and may be
fatal if swallowed. Wash hands thoroughly
after handling.) Typical stock solution
preparation procedures follow.
6.1.3.1 Aluminum solution, stock, 1 it ° 100 ug
Al: Dissolve 0.100 g aluminum metal in an
acid mixture of 4 mL of (1+1) HCl and 1 mL
of conc. HNOj in a beaker. Warm gently to
effect solution. When solution is
complete, transfer quantitatively to a
one-liter flask, add an additional 10 mL
(1+1) HCl, and dilute to 1000 mL with
deionized distilled water.
6.1.3.2 Antimony solution stock, 1 mL = 100 ug Sb:
Dissolve 0.2669 g K(Sb0)C,H^06 in
deionized distilled water, add 10 mL (1+1)
HCl and dilute to 1000 mL with deionized
distilled water.
6.1.3.3 Arsenic solution, stock, 1 mL = 100 ug As:
Dissolve 0.1320 g As2°3 ,n 100 mL
deionized distilled water containing 0.4 g
NaOH. Acidify the solution with 2 mL
conc. HNO^ and dilute to 1000 mL with
deionized distilled water.
6.1.3.4 Barium solution, stock, 1 mL = 100 ug Ba:
Dissolve 0.1516 g BaCl- (dried at 250 °C
for 2 hours) in 10 mL deionized distilled
water with 1 mL (1+1) HCl. Add 10.0 mL
(1+1) HCl and dilute to 1000 mL with
deionized distilled water.
6.1.3.5 Beryllium solution, stock, 1 mL = 100 ug
Be: Do not dry. Dissolve 1.966 g
BeSO.^H^O, in deionized distilled water,
add 10.0 mL conc. HNO^ and dilute to 1000
mL with deionized distilled water.
6.1.3.6 Boron solution, stock, 1 ni = 100 ug B:
Do not dry. Dissolve 0.5716 g anhydrous
H^BOj in deionized distilled water and
dilute to 1000 nl. Use a reagent meeting
ACS specifications, keep the bottle
tightly stoppered, and store in a
desiccator to prevent the entrance of
atmospheric moisture.
6.1.3.7 Cadmium solution, stock, 1 mL = 100 ug Cd:
Dissolve 0.1142 g CdO in a minimum amount
of (1+1) HNO^. Heat to increase rate of
dissolution. Add 10.0 mL conc. HNO^ and
dilute to 1000 mL with deionized distilled
water.
6.1.3.8 Calciun solution, stock, 1 mL ® 100 ug Ca:
Suspend 0.2498 g CaCOj (dried at 180 °C
for one hour before weighing) in deionized
distilled water, and dissolve cautiously
with a mini nun amount of (1+1) HNQ.. Add
10.0 mL conc. HNOj and dilute to 1000 mL
with deionized distilled water.
9
-------
6.1.3.9
6.1.3.10
6.1.3.11
6.1.3.12
6.1.3.13
6.1.3.14
Chromium solution, stock, 1 mL = 100 ug
Cr: Dissolve 0.1923 g CrOj in deionized
distilled water. When solution is
complete, acidify with 10 mL conc. HN
and dilute to 1000 mL with deioniz
distilled water.
Cobalt solution stock, 1 mL a 100 ug Co:
Dissolve 0.1000 g of cobalt metal in a
minimun amount of (1+1) HNOj. Add 10.0 mL
6.1.3.19
(1+1) HCl and dilute to~
deionized distilled water.
1000 mL with
Copper solution, stock, 1 mL = 100 ug Cu:
Dissolve 0.1252 g CuO in a minimum amount
of (1+1) HMO,. Add 10.0 mL conc. HNOj and
dilute to 1000 mL with deionized distilled
water.
Iron solution, stock, 1 mL 3 100 ug Fe:
Dissolve 0.1430 g I^Oj in a warm mixture
of 20 mL (1+1) HCl and 2 mL conc. HNOj.
Cool, add an additional 5 mL conc. HNOj,
and dilute to 1000 mL with deionized
distilled water.
Lead solution, stock, 1 mL = 100 ug Pb:
Dissolve 0.1599 g Pb(NOj)£ in a minimun
amount of (1+1) HNOj. Add 10.0 mL of
conc. HNOj and dilute to 1000 mL with
deionized distilled water.
Magnesium solution, stock, 1 mL = 100 ug
Mg: Dissolve 0.1658 g HgO in a minimum
amount of (1+1) HNOj. Add 10.0 mL conc.
HNOj and dilute to 1000 mL with deionized
distilled water.
6.1.3.20
6.1.3.21
6.1.3.22
6.1.3.23
6.1.3.24
Silver solution, stock, 1 mL = 100 ug Ag:
Dissolve 0.1575 g AgNOj in 100 mL
deionized distilled water and 10 mL conc.
HNOj. Dilute to 1000 mL with deionized
distilled water.
Sodium solution, stock, 1 mL = 100 ug Na:
Dissolve 0.2542 g NaCl in deionized
distilled water. Add 10.0 mL conc. HNC
and dilute to 1000 mL with dei
distilled water.
tc. HNOj
;ionized
Thallium solution, stock, 1 mL = 100 ug
Tl: Dissolve 0.1303 g TINOj in deionized
Add 10.0 mL conc. HNOj
distilled water
and dilute to
distilled water
1000 mL with deionized
Tin solution, stock, 1 mL = 100 ug Sn:
Dissolve 0.1000 g of tin metal in 80 mL
conc. HCl and dilute to 1000 mL with
deionized distilled water. NOTE: It is
preferable to maintain the tin standard in
8-20 percent HCl to overcome the problem
of precipitation and colloidal formation.
= 100 ug Ti:
in 50 mL conc.
Titaniun, stock, 1 mL
Dissolve 0.3220 g TiClj
HCl. Dilute to 1000 mL with deionized
distilled water.
Vanadium solution, stock, 1 mL = 100 ug V:
Dissolve 0.2297 NH^VOj in a minimum amount
of conc. HNOj. Heat to increase rate of
dissolution. Add 10.0 mL conc. HNOj and
dilute to 1000 mL with deionized distilled
water.
6.1.3.15 Manganese solution, stock, 1 mL = 100 ug
Mn: Dissolve 0.1000 g manganese metal in
10 mL conc. HCl and 1 mL conc. HNOj, and
dilute to 1000 mL with deionized distilled
water.
6.1.3.25 Yttrium solution, stock, 1 mL = 100 ug Y:
Dissolve 0.43080 g Y(NOj)j"6H20 in
deionized distilled water. Add 50 mL
conc. HNOj and dilute to 1000 mL with
deionized distilled water.
6.1.3.16 Molybdenun solution, stock, 1 iL > 100 ug 6.1.3.26
Mo: Dissolve 0.2043 g (NH^)2Mo0^ in
deionized distilled water and dilute to
1000 mL.
6.1.3.17 Nickel solution, stock, 1 mL = 100 ug Ni:
Dissolve 0.1000 g of nickel metal in 10 mL
hot conc. HNOj, cool and dilute to 1000 mL
with deionized distilled water. 6.1.4.1
6.1.3.18 Selenium solution, stock, 1 mL = 100 ug
Se: Do not dry. Dissolve 0.1727 g H^SeOj
(actual assay 94.6X) in deionized
distilled water and dilute to 1000 mL.
Zinc solution, stock, 1 mL = 100 ug Zn:
Dissolve 0.1245 g ZnO in a minimum amount
of dilute HNOj. Add 10.0 mL conc. HNOj
and dilute to
distilled water.
1000 mL with deionized
6.1.4 Mixed calibration standard solutions
Prepare mixed calibration standard
solutions by combining appropriate volunes
of the stock solutions in volunetric
flasks. (Recommended solutions are given
in Sections 6.1.4.4.1-6.1.4.4.5.). Add 2
mL (1+1) HNOj and 10 mL (1+1) HCl, and
dilute to 100 mL with deionized distilled
water. (See NOTE in Section 6.1.4.4.5.)
10
-------
Prior to preparing the mixed standards,
each stock solution should be analyzed
separately to determine possible spectral
interference or the presence of
impurities. Care should be taken when
preparing the mixed standards that the
elements are compatible and stable.
Transfer the mixed standard solutions to a
FEP fluorocarbon or unused polyethylene
bottle for storage.
6.1.4.2 The calibration standards must contain the
same acid concentration as the prepared
sample. Fresh mixed standards should be
prepared as needed, recognizing that
concentration can change over time. 6.1
.4.3 Calibration standards must be
initially verified using an ICV standard
and monitored weekly for stability (see
Section 8.4.1.1).
6.1.4.4 Typical calibration standard combinations
are given in Sections 6.1.4.4.1 through
6.1.4.4.5. Although not specifically
required, these combinations are
appropriate when using the specific
wavelengths listed in Table 1.
6.1.4.4.1 Mixed standard solution I - Manganese,
beryllium, cadmium, lead, and zinc.
6.1.4.4.2 Mixed standard solution II -- Barium,
copper, iron, vanediun, yttrium, and
cobalt.
6.1.4.4.3 Mixed standard solution III -- Molybdenum,
arsenic, and selenium.
6.1.4.4.4 Mixed standard solution IV -• Calcium,
sodium, aluminum, chromium and nickel.
6.1.4.4.5 Mixed standard solution V -- Antimony,
boron, magnesium, silver, thalliun, and
titanium. NOTE: If the addition of
silver to the recommended acid combination
results in an initial precipitation, add
15 mL of deionized distilled water and
warm the flask until the solution clears.
Cool and dilute to 100 mL with deionized
distilled water. For this acid
combination, the silver concentration
should be limited to 2 rog/l. Silver under
these conditions is stable in a tap water
matrix for 30 days. Higher concentrations
of silver require additional HCl.
6.1.4.4.6 Standard solution VI -- Tin.
6.1.5 Initial calibration verification (ICV)
standard solutions -- Prepared in the same
acid matrix as the calibration standards
(see Section 6.1.4) and in accordance with
the instructions provided by the supplier.
Certified ICV standard solutions should be
obtained from an outside source. If the
certified solution of the ICV standard is
not available from any source, analyses
shall be conducted on an independent
standard (defined as a standard cotrposed
of the analytes from a different source
than those used in the standards for the
instrument calibration) at a concentration
other than that used for instrument
calibration but within the calibration
range. NOTE: ICV standards for
semiquantitative ICP screen elements are
not available commercially at this time
and should be prepared by the laboratory.
The standards used must be traceable to
EPA or N1ST materials.
6.1.6 Continuing calibration verification (CCV)
standard solutions -- Prepared by
containing compatible elements at a
concentration equivalent to the midpoints
of their respective calibration curves.
The aggregated CCV standard solutions must
contain all analytes. The CCV standard
may be an outside standard of NIST or EPA
materials, NIST SRM 1643a, or laboratory-
prepared standards traceable to EPA or
NIST.
6.1.7 ICP interference check sample (ICS) -- The
ICP ICS consists of two solutions:
Solution A (interferents) and Solution AB
(analytes mixed with the interferents).
The materials used in the ICS must be
traceable to NIST or EPA material.
6.1.7.1 If the ICP ICS is not available from any
source, the laboratory must prepare
independent ICP check samples with
interferent and analyte concentrations at
the levels specified in Table 11.
6.1.7.2 The mean value and standard deviation of
independent ICP check samples must be
established by initially analyzing the
check samples at least five times
repetitively for each parameter in Table
11. Results must fall within the control
limit of +20% of the established mean
value.
6.1.8 Blanks -- Two types of blanks are
required. Initial and continuing
calibration blanks are used in
establishing the analytical curve; the
preparation (reagent) blank is used to
11
-------
correct for possible contamination
resulting from varying amounts of the
acids used in the sample processing.
6.1.8.1 Initial and continuing calibration blanks
-- Prepared by diluting 2 mL of (1+1) HNCL
and 10 mL of (1+1) HCl to 100 mL with
deionized distilled water. Prepare a
sufficient quantity to be used to flush
the system between standards and samples.
The calibration blank must contain the
same acid concentration as the prepared
sample solution.
6.1.8.2 Preparation (reagent) blank -- Must
contain all the reagents and in the same
volumes as used in the processing of the
samples. The preparation blank must be
carried through the complete procedure and
contain the same acid concentration in the
final solution as the sample solution used
for analysis.
6.1.9 Laboratory control sample -- Should be
obtained from an outside source. If
unavailable, the ICV standard solutions
may be used. The laboratory control
sample must contain all analytes of
interest. Standards used must be
traceable to NIST or EPA material.
6.2 ICP-Atomic Absorption Spectrometry
Semiquantitative screening of 42 elements
6.2.1 Individual stock solution (1000 mg/L) for
the elements listed in Table 4 may be
prepared by the laboratory or purchased
from a commercial source. These solutions
are available from J.T. Baker Alfa
Products and other suppliers.
6.2.1.1 Osmiun stock solution: Osmiisn stock
solution can be prepared from osmium
chloride (available from Alfa Products or
other suppliers). Dissolve 1.559 g OsCl^
in 6 mL cor>c. HCl + 2 mL conc. HNQj, and
dilute to 1 liter to yield 1000 mg/L stock
solution.
6.2.1.2 Sulfur stock solution: Can be prepared
from ammonium sulfate (available from J.
T. Baker or other suppliers). Dissolve
4.122 g of anhydrous ammonium sulfate in
deionized water and dilute to 1 liter to
yield 1000 mg/L stock solution.
6.2.1.3 Uranium stock solution: Made from uranyl
nitrate (available from Alfa Products or
other suppliers). Dissolve 2.110 g uranyl
nitrate hexahydrate in 6 mL conc. HCl + 2
mL conc. HNO, and dilute to 1 liter to
give 1000 mg/L.
6.2.2 Mixed calibration solution -- Prepare a
mixed working (calibration) standard
directly from the individual stock
solutions to give final concentrations for
each analyte as listed in Table 7. It is
recommended that a micro-pipette with
disposable plastic tips be used to
transfer each stock solution to the
volumetric flask. The stability of this
solution is limited, but can be extended
by storing it in a dark brown plastic
bottle away from light. Care should be
taken to include analyte contribution from
other stock standards. For example: a
number of the stock standards are prepared
from potassium salts. If alternative
solutions are not available, the final
solution (Section 6.2.2) must be analyzed
quantitatively by ICP to derive its true
concentration. The resulting calibration
standard must contain the same acid
concentration as the prepared sample
solution.
6.2.3 ICV standard solutions (see Section
6.1.5), CCV standard solutions (see
Section 6.1.6), and interference check
samples (see Section 6.1.7) are also
required.
6.2.4 Two types of blanks are required --
Initial and continuing calibration blanks
and the preparation blank (see Section
6.1.8).
6.3 GFAA Spectrophotometry Method
6.3.1 Antimony
6.3.1.1 Stock solution: Carefully weigh 2.669 g
of antimony potassium tartrate (analytical
reagent grade) and dissolve in deionized
distilled water. Dilute to 1 liter with
deionized water. 1 mL = 1 mg Sb (1000
mg/L).
6.3.1.2 Prepare dilutions of the stock solution to
be used as calibration standards at the
time of analysis. These solutions are
also to be used for "standard additions."
6.3.1.3 The calibration standards must be prepared
using the same type of acid and at the
same concentration as will result in the
sample to be analyzed after sample
preparation.
12
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6.3.2 Arsenic
6.3.2.1 Stock solution: Dissolve 1.320 g arsenic
trioxide, ASjO^ (analytical reagent grade)
in 100 mL de ionized distilled water
containing 4 g NaOH. Acidify the solution
with 20 mL conc. HNOj and dilute to 1
liter. 1 mL = 1 rag As (1000 mg/L).
6.3.2.2 Nickel nitrate solution, SX: Dissolve
24.770 g ACS reagent grade NkNO^^I^O
in deionized distilled water and make up
to 100 mL.
6.3.2.3 Nickel nitrate solution, 1%: Dilute 20 mL
of the 5X nickel nitrate to 100 mL with
deionized distilled water.
6.3.2.4 Working arsenic solution: Prepare
dilutions of the stock solution to be used
as calibration standards at the time of
analysis. Withdraw appropriate aliquots
of the stock solution, add 1 mL conc.
HM0-, 2 mL 30* H_02, and 2 mL of the 5%
nickel nitrate solution. Dilute to 100 mL
with deionized distilled water.
make up to 200 mL. 1 mL = 1 mg Se (1000
mg/L).
6.3.4.2 Nickel nitrate solution, 5X: Dissolve
24.770 g ACS reagent grade NUNO^^I^O
in deionized distilled water and make up
to 100 mL.
6.3.4.3 Nickel nitrate solution, 1X: Dilute 20 mL
of the 5X nickel nitrate to 100 mL with
deionized distilled water.
6.3.4.4 Working selenium solution: Prepare
dilutions of the stock solution to be used
as calibration standards at the time of
analysis. The calibration standards must
be prepared using the same type of acid
and at the same concentration as will
result in the sample to be analyzed after
sample preparation. Withdraw appropriate
aliquots of the stock solution, add 1 mL
conc. HNOj, 2 mL 30X HjOg, and 2 mL of the
5X nickel nitrate solution. Dilute to 100
mL with deionized distilled water.
6.3.5 Thallium
6.3.3 Lead
6.3.3.1 Stock solution: Carefully weigh 1.599 g
lead nitrate, Pb(N0,), (analytical reagent
grade), and dissolve in deionized
distilled water. When solution is
complete, acidify with 10 mL redistilled
HNOj and dilute to 1 liter with deionized
distilled water. 1 mL = 1 mg Pb (1000
mg/L).
6.3.3.2 Lanthanun nitrate solution: Dissolve
58.639 g of ACS reagent grade La.O- in 100
mL conc. HNOj and dilute to 10$) mL with
deionized distilled water. 1 mL = 50 mg
La.
6.3.3.3 Working lead solution: Prepare dilutions
of stock lead solution to be used as
calibration standards at the time of
analysis. The calibration standards must
be prepared using the same type of acid
and at the same concentration as will
result in the santple to be analyzed after
sample preparation. To each 100 mL of
di luted standard, add 10 mL of the
lanthanum nitrate solution.
6.3.4 Seleniun
6.3.4.1 Stock selenium solution: Dissolve 0.3453
g selenous acid (actual assay 94.6X
HjSeQj) in deionized distilled water and
6.3.5.1 Stock solution: Dissolve 1.303 g thallium
nitrate, TINO^ (analytical reagent grade)
in deionized distilled water. Add 10 mL
conc. nitric acid and dilute to 1 liter
with deionized distilled water. 1 mL = 1
mg Tl (1000 mg/L).
6.3.5.2 Prepare dilutions of the stock solution to
be used as calibration standards at the
time of analysis. These solutions are
also to be used for "standard additions."
6.3.5.3 The calibration standards must be prepared
using the same type of acid and at the
same concentration as will result in the
sample to be analyzed after sample
preparation.
6.4 Mercury Analysis in Water by Manual Cold
Vapor Technique
6.4.1 Sulfuric acid, conc: Reagent grade.
6.4.1.1 Sulfuric acid, 0.5 N: Dilute 14.0 mL
conc. sulfuric acid to 1.0 liter.
6.4.2 Nitric acid, conc: Reagent grade of low
mercury content. NOTE: If a high reagent
blank is obtained, it may be necessary to
distill the nitric acid.
6.4.3 Stannous sulfate: Add 25 g stannous
sulfate to 250 mL 0.5 N sulfuric acid.
This mixture is a suspension and should be
13
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stirred continuously during use. NOTE:
Stannous chloride may be used in place of
stannous sulfate.
6.4.4 Sodiun chloride-hydroxylamine sulfate
solution: Dissolve 12 g sodiun chloride
and 12 g hydroxy I amine sulfate in
deionized distilled water, and dilute to
100 mL. NOTE: HydroxyIamine
hydrochloride may be used in place of
hydroxylamine sulfate.)
6.4.5 Potassium permanganate: 5X solution, w/v.
Dissolve 5 g potassium permanganate in 100
mL distilled water.
6.4.6 Potassium persulfate: 5X solution, w/v.
Dissolve 5 g potassium persulfate in 100
id distilled water.
6.4.7 Stock mercury solution: Dissolve 0.1354 g
mercuric chloride in 75 mi. deionized
distilled water. Add 10 mL cortc. nitric
acid and adjust the volune to 100.0 mL. 1
mL = 1 mg Hg.
6.4.8 Working mercury solution: Hake successive
dilutions of the stock mercury solution to
obtain a working standard containing 0.1
ug per mL. This working standard and the
dilutions of the stock mercury solution
should be prepared fresh daily. Acidity
of the working standard should be
maintained at 0.15X nitric acid. This
acid should be added to the flask as
needed before the addition of the aliquot.
6.5 Mercury Analysis in Water by Automated
Cold Vapor Technique
6.5.1 Sulfuric acid, cone: Reagent grade.
6.5.1.1 Sulfuric acid, 2 N: Dilute 56 mL conc.
sulfuric acid to 1 liter with deionized
distilled water.
6.5.1.2 Sulfuric acid, 10%: Dilute 100 mL conc.
sulfuric acid to 1 liter with deionized
distilled water.
6.5.2 Nitric acid, conc: Reagent grade of low
mercury content.
6.5.2.1 Nitric acid, 0.5X wash solution: Dilute 5
mL conc. nitric acid to 1 liter with
deionized distilled water.
6.5.3 Stannous sulfate: Add 50 g stannous
sulfate to 500 mL 2N sulfuric acid
(Section 6.5.1.1). This mixture is a
suspension and should be stirred
continuously during use. NOTE: Stannous
chloride may be used in place of stannous
sulfate.
6.5.4 Sodiun chloride-hydroxylamine sulfate
solution: Dissolve 30 g sodiun chloride
and 30 g hydroxylamine sulfate in
deionized distilled water and dilute to 1
liter. NOTE: Hydroxylamine hydrochloride
may be used in place of hydroxylamine
sulfate.
6.5.5 Potassiun permanganate: See Section
6.4.5.
6.5.6 Potassiun permanganate, 0.1N: Dissolve
3.16 g potassiun permanganate in deionized
distilled water and dilute to 1 liter.
6.5.7 Potassiun persulfate: See Section 6.4.6.
6.5.8 Stock mercury solution: See Section
6.4.7.
6.5.9 Working mercury solution: See Section
6.4.8. From this solution, prepare
standards containing 0.2, 0.5, 1.0, 2.0,
5.0, 10.0, 15.0, and 20.0 ug Hg/L.
6.5.10 Air scrubber solution: Mix equal volumes
of 0.1 N potassiun permanganate (Section
6.5.6) and 10X sulfuric acid (Section
6.5.1.2).
6.6 Mercury Analysis in Soil/Sediments by
Manual Cold Vapor Technique
6.6.1 Sulfuric acid, conc: Reagent grade of low
mercury content.
6.6.2 Nitric acid, conc: See Section 6.4.2.
6.6.3 Stannous sulfate: See Section 6.4.3.
6.6.4 Sodium chloride-hydroxylmine sulfate: See
Section 6.4.4.
6.6.5 Potassium permanganate: See Section
6.4.5.
6.6.6 Potassiun persulfate: See Section 6.4.6.
6.6.7 Stock mercury solution: See Section
6.4.7.
6.6.8 Working mercury solution: See Section
6.4.8.
14
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7 CALIBRATION
7.1 ICP and GFAA Spectroscopic Methods
7.1.1 Operating conditions -- Because of the
differences between various makes and
models of satisfactory instruments, no
detailed operating instructions can be
provided. Instead, the analyst should
follow the instructions provided by the
manufacturer of the particular instrument.
Sensitivity, instrumental detection limit,
precision, linear dynamic range, and
interference effects must be investigated
and established for each individual
analyte line on that particular
instrument. All measurements must .be
within the instrunent linear range where
correction factors are valid.
7.1.2 It is the responsibility of the analyst to
verify that the instrunent configuration
and operating conditions used satisfy the
analytical requirements and to maintain
quality control data confirming instrunent
performance and analytical results.
7.2 Analysis of Mercury in Uater by Cold Vapor
Technique
7.2.1 Transfer 0, 0.5, 1.0, 5.0 and 10.0 mL
aliquots of the working mercury solution
containing 0 to 1.0 ug mercury to a series
of 300 mL BOO bottles. Add enough
distilled water to each bottle to make a
total volume of 100 mL. Mix thoroughly
and add 5 mL cone, sulfuric acid (Section
6.4.1) and 2.5 mL conc. nitric acid
(Section 6.4.2) to each bottle. Add 15 mL
KMnO, (Section 6.4.5) solution to each
bottle and allow to stand at least 15
minutes. Add 8 mL potassiun persulfate
(Section 6.4.6) to each bottle and heat
for 2 hours in a water bath maintained at
95 8C. Alternatively, cover the BOO
bottles with foil and heat in an autoclave
for 15 minutes at 120 °C and 15 psi. Cool
and add 6 mL of sodium chloride-
hydroxylamine sulfate solution (Section
6.4.4) to reduce the excess permanganate.
When the solution has been decolorized,
wait 30 seconds, add 5 mL of the stannous
sulfate solution (Section 6.4.3), and
immediately attach the bottle to the
aeration apparatus forming a closed
system. At this point, the sample is
allowed to stand quietly without manual
agitation.
7.2.2 The circulating punp, which has previously
been adjusted to a rate of 1 liter per
minute, is allowed to run continuously
(see NOTE 1). The absorbance will
increase and reach maximun within 30
seconds. As soon as the recorder pen
levels off, approximately 1 minute, open
the bypass valve and continue the aeration
until the absorbance returns to its
minimun value (see NOTE 2). Close the
bypass valve, remove the stopper and frit
from the BOO bottle and continue the
aeration. Proceed with the standards and
construct a standard curve by plotting
peak height versus micrograms of mercury.
NOTE 1: An open system (where the mercury
vapor is passed through the absorption
cell only once) may be used instead of the
closed system.
NOTE 2: Because of the toxic nature of
mercury vapor, precautions must be taken
to avoid its inhalation. Therefore, a
bypass has been included in the system to
either vent the mercury vapor into an
exhaust hood or pass the vapor through
some absorbing media, such as: a) equal
volumes of 0.1 M KMnO, and 10X H-SO^, or
b) 0.25X iodine in a 3% KI solution. A
specially treated charcoal that will
adsorb mercury vapor is available.
7.2.3 If additional sensitivity is required, a
200 mL sample with recorder expansion may
be used provided the instrument does not
produce undue noise.
7.3 Analysis of Mercury in Soil/Sediments by
Cold Vapor Technique
7.3.1 Transfer .0, 0.5, 1.0, 5.0, and 10 mL
aliquots of the working mercury solutions
(Section 6.6.8) containing 0-1.0 ug
mercury to a series of 300 mL BOO bottles.
Add enough deionized distilled water to
each bottle to make a total volume of 100
mL. Add 5 mL conc. H^SO^ (Section 6.6.1)
and 2.5 mL conc. HNOj (Section 6.6.2), and
heat for 2 minutes in a water bath at 95
°C. Allow the sample to cool. Add 50 mL
deionized distilled water, 15 mL KMnO^
solution (Section 6.6.5), and 8 mL
potassiun persulfate solution (Section
6.6.6) to each bottle and return bottles
to the water bath for 30 minutes. Cool
and add 6 mL sodiun chloride-hydroxylamine
sulfate solution (Section 6.6.4) to reduce
the excess permanganate. Add 50 mL
deionized distilled water. Treating each
15
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bottle individually, add 5 mL stannous
sulfate solution (Section 6.6.3) and
immediately attach the bottle to the
aeration apparatus. At this point, the
sample is allowed to stand quietly without
manual agitation.
7.3.2 The circulating pump, which has previously
been adjusted to a rate of 1 liter per
minute, is allowed to run continuously
(see NOTE 1 in Section 7.2.2). The
absorbance, as exhibited either on the
spectrophotometer or the recorder, will
increase and reach maximum within 30
seconds. As soon as the recorder pen
levels off, approximately 1 minute, open
the bypass valve and continue the aeration
until the absorbance returns to its
minimum value (see NOTE 2 in Section
7.2.2). Close the bypass valve, remove
the fritted tubing from the BOO bottle and
continue the aeration. Proceed with the
standards and construct a standard curve
by plotting peak height versus micrograms
of mercury.
8 QUALITY ASSURANCE/QUALITY CONTROL
8.1 Each laboratory that uses this method is
required to operate a formal quality
assurance program. The minimum require-
ments of this program consist of: 1) an
initial demonstration of laboratory
capability, 2) analysis of samples spiked
with the analytes of interest to evaluate
and docunent data quality, and 3) analysis
of standards and blanks as tests of
continued performance. Laboratory
performance is compared to established
performance criteria to determine if the
results of analyses meet the performance
characteristics of the method.
8.1.1 The analyst shall make an initial
demonstration of the ability to generate
acceptable accuracy and precision with
this method. This ability is established
as described in Section 8.2.
8.1.2 The analyst is permitted to modify this
method to lower the costs of measurements,
provided all performance specifications
are met. Each time a modification is made
to the method, the analyst is required to
repeat the procedure in Section 8.2 to
demonstrate method performance.
8.2 Initial Precision and Accuracy -- To
establish the ability to generate
acceptable precision and accuracy, the
analyst shall perform the following
operations.
8.2.1 For analysis of samples containing low
solids (aqueous samples), prepare four 500
mL aliquots of reagent water spiked with
the 27 elements listed in Tables 1-2 at
concentrations at or near the MLs given in
Table 9. Digest these samples according
to the procedures in Section 10.1.1 and
analyze the samples according to the ICP,
GFAA and Hg procedures in Sections 10.1.3,
10.3, and 10.4, respectively.
8.2.2 For analysis of samples containing high
solids, prepare four aliquots of reagent
water containing the 27 elements at
concentrations at or near the detection
limits given in Tables 1-2. Digest these
samples according to the procedures for
water samples in Section 10.1.1, but
analyze them as if they were soil samples
according to Sections 10.1.3, 10.3, and
10.4, and calculate the concentrations of
the analytes as if the original sample
weight was 1 g of soil.
8.2.3 Using the results of the set of four
analyses (from Section 8.2.1 or 8.2.2),
compute the average percent recovery (x)
and the coefficient of variation (s) of
the percent recovery(ies) for each
element.
8.2.4 For each element, compare s and x with the
corresponding limits in Table 8. If s and
x for all elements meet the acceptance
criteria, system performance is
acceptable, and analysis of blanks and
samples may begin. If, however, any
individual s exceeds the precision limit
or any individual x falls outside the
range for accuracy, system performance is
unacceptable for the element. In this
case, correct the problem and repeat the
test.
8.3 Instrument Calibration
8.3.1 Guidelines for instrunental calibration
are given in EPA 600/4-79-020 and/or
Section 7. Instruments must be calibrated
daily or once every 24 hours and each time
the instrument is set up.
8.3.2 For atomic absorption systems, calibration
standards are prepared by diluting the
stork metal solutions at the time of
analysis.
16
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8.3.3 Calibration standards
8.3.3.1 For ICP systems, calibrate the instrument
according to instrument manufacturer's
recommended procedures. At least two
standards must be used for ICP
calibration. One of the standards must be
a blank.
8.3.3.2 AA Systems
8.3.3.2.1 Calibration standards for AA procedures
must be prepared by dilution of the stock
solutions (Section 6.3).
8.3.3.2.2 Calibration standards must be prepared
fresh each time an analysis is to be made
and discarded after use. Prepare a blank
and at least three calibration standards
in graduated amounts in the appropriate
range. One atomic absorption calibration
standard must be at the minimum level (see
Table 9), except for mercury. The
calibration standards must be prepared
using the same type of acid or combination
of acids and at the same concentration as
will result in the samples following
sample preparation.
8.3.3.2.3 Beginning with the blank, aspirate or
inject the standards and record the
readings. If the AA instrument
configuration prevents the required four-
point calibration, calibrate according to
instrument manufacturer's recommendations,
and analyze the remaining required
standards iimtediately after calibration.
Results for these standards must be uithin
± 5X of the true value. Each standard
concentration and the calculations to show
that the ± 5% criterion has been met, must
be given in the raw data. If the values
do not fall uithin this range,
recalibration is necessary. NOTE: The t
5% criteria does not apply to the atomic
absorption calibration standard at the
mininun level.
8.3.3.2.4 Baseline correction is acceptable as long
as it is performed after every sample or
after the continuing calibration
verification and blank check; res loping is
acceptable as long as it is immediately
preceded and immediately followed by
continuing calibration verification and
continuing calibration blank analyses.
8.3.4 Mercury analysis techniques -- Follow the
calibration procedures outlined in Section
7.
8.4 Initial Calibration Verification (ICV) and
Continuing Calibration Verification (CCV)
8.4.1 Initial Calibration Verification (ICV)
8.4.1.1 The accuracy of the initial calibration
shall be verified and docunented for every
analyte by the analysis of an ICV standard
(Sections 6.1.5 and 6.2.3) at each
wavelength used for analysis. If the
results are not within t10% of the true
value, the analysis must be terminated,
the problem corrected, the instrunent
recalibrated, and the calibration
reverified. NOTE: For semiquantitative
ICP analysis, prepare a new calibration
standard and recalibrate the instrument.
If this does not correct the problem,
prepare a new stock standard and a new
calibration standard, and repeat the
calibration.
8.4.1.2 ICV standard solutions must be run
immediately after each of the ICP and AA
systems have been calibrated and each time
the system is set up. The ICV standard
solution(s) must be run for each analyte
at each wavelength used for analysis.
8.4.2 Continuing Calibration Verification (CCV)
8.4.2.1 To ensure calibration accuracy during each
analysis run, a CCV standard (Sections
6.1.6 and 6.2.3) is to be used for
continuing calibration verification and
must be analyzed and reported for every
wavelength used for the analysis of each
analyte, at a frequency of 10% or every 2
hours during an analysis run, whichever is
more frequent. The CCV standard must also
be analyzed and reported for every
wavelength used for analysis of each
analyte at the beginning of the run and
after the last analytical sample.
8.4.2.2 The same continuing calibration standard
must be used throughout the analysis run
for each set or Episode of samples
received.
8.4.2.3 Each CCV standard analysis must reflect
the conditions of analysis of all
associated analytical samples (all
preceding analytical samples up to the
previous CCV standard analysis). The
duration of analysis, rinses and other
related operations that may affect the CCV
measured result may not be applied to the
CCV standard to a greater extent than the
extent applied to the associated
17
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analytical samples. For instance, the
difference in time between a CCV standard
analysis and the blank immediately
following it, as well as the difference in
time between the CCV standard analysis and
the analytical sample immediately
preceding it, may not exceed the lowest
difference in time between analysis of any
two consecutive analytical samples
associated with the CCV.
8.4.2.4 If the deviation of the continuing
calibration verification is greater than
the control limits specified in Table 10,
the analysis must be stopped, the problem
corrected, the instrument recalibrated,
the calibration verified, and the
preceding samples analyzed since the last
good calibration verification reanalyzed
for the analytes affected.
8.5 Mininun Level (ML) Standards for ICP (CRI)
and AA (CRA)
8.5.1 To verify linearity near the ML for ICP
analysis, analyze an ICP standard (CRI) at
2x ML (Table 9) or 2x IDL, whichever is
greater, at the beginning and end of each
sample analysis run, or a minimum of twice
per 8-hour working shift, whichever is
more frequent, but not before initial
calibration verification. This standard
must be run by ICP for every wavelength
used for analysis, except those for Al,
Ba, Ca, Fe, Mg, Na and K.
8.5.2 To verify linearity near the ML for AA
analysis, analyze an AA standard (CRA) at
the ML or the IDL, whichever is greater,
at the beginning of each sample analysis
run, but not before the initial
calibration verification.
8.5.3 If any GFAA element exceeds the ICP ML by
2x, it can be analyzed by ICP rather than
GFAA.
8.5.4 Report percent recoveries for the CRI and
CRA standards. Specific acceptance
criteria for these standards will be set
by EPA in the future.
8.6 Initial Calibration Blank (ICB),
Continuing Calibration Blank (CCB), and
Preparation Blank (PB) Analyses
8.6.1 Initial and continuing calibration blank
analyses -- A calibration blank (Section
6.1.8.1 and 6.2.4) must be analyzed at
each wavelength used for analysis,
immediately after every initial and
continuing calibration verification, at a
frequency of 10% or each time the
instrument is calibrated, whichever is
more frequent. The blank must be analyzed
at the beginning of the run and after the
last analytical sample. NOTE: A CCB
must be run after the last CCV that was
run after the last analytical sample of
the run.
8.6.1.1 For quantitative ICP analysis, if the
absolute value blank result exceeds the ML
(Table 9), terminate analysis, correct the
problem, recalibrate, verify the
calibration, and reanalyze the preceding
10 analytical samples or all analytical
samples analyzed since the last acceptable
calibration blank analysis.
8.6.1.2 For semiquantitative ICP analysis, the
absolute value of the blank result must be
less than the lower threshold limit (Table
4). If the result is not within the LTL,
terminate the analysis, correct the
problem, and recalibrate the instrument.
8.6.2 Preparation blank analysis -- At least one
preparation (reagent) blank (Sections
6.1.8.2 and 6.2.4) must be prepared and
analyzed with each batch of samples (group
of samples prepared at the same time)
digested. This blank is to be reported
for each batch of samples and used in all
analyses to ascertain whether sample
concentrations reflect contamination.
8.6.2.1 If the absolute value of the concentration
of the blank is less than or equal to the
ML (Table 9), no correction of sample
results is performed.
8.6.2.2 If any analyte concentration in the blank
is above the ML (Table 9), the lowest
concentration of that analyte in the
associated samples must be 10x the blank
concentration. Otherwise, all samples
associated with the blank with the
analyte's concentration less than lOx the
blank concentration and above the ML, must
be redigested and reanalyzed for that
analyte. The sample concentration is not
to be corrected for the blank value.
8.6.2.3 If the concentration of the blank is below
the negative ML, then all samples reported
below 10x ML associated with the blank
must be redigested and reanalyzed.
18
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8.7 ICP Interference Check Sample (ICS)
Analysis
8.7.1 To verify inter-element and background
correction factors, analyze and report the
results for the ICP ICS (Sections 6.1.7
and 6.2.3) at the beginning and end of
each analysis run or a mininun of twice
per 8-hour working shift, whichever is
more frequent, but not before initial
calibration verification.
8.7.2 The ICP ICS consists of two solutions:
Solution A (interferents) and Solution AB
(analytes mixed with the interferents).
An ICS analysis consists of analyzing both
solutions consecutively (starting with
Solution A) for all wavelengths used for
each analyte reported by ICP.
8.7.3 Results for the ICP analyses of Solution
AB during the analytical runs must fall
within the control limit of +20% of the
true value for the analytes included in
the ICS. If not, terminate the analysis,
correct the problem, recalibrate the
instrument, and reanalyze the analytical
samples analyzed since the last acceptable
ICS. If true values for analytes
contained in the ICS and analyzed by ICP
are not supplied with the ICS, the mean
must be determined by initially analyzing
the ICS at least five times repetitively
for the particular analyte(s). This mean
determination must be made during an
analytical run where the results for the
previously-analyzed ICS met all method
specifications. Additionally, the result
of this initial mean determination is to
be used as the true value for the lifetime
of that solution (i.e., until the solution
is exhausted).
8.8 Spike Sample Analysis (Matrix Spike)
8.8.1 The spike sample analysis is designed to
provide information about the effect of
the sample matrix on the digestion and
measurement methodology. The spike is
added before the digestion (i.e., prior to
the addition of other reagents) and prior
to any distillation steps. Spike sample
analyses shall be performed on 10X of the
samples analyzed, or at least one spike
sample analysis (matrix spike) shall be
performed for each set or Episode of
samples, whichever is more frequent.
8.8.2 If the spike analysis is performed on the
same sample that is chosen for the
duplicate sairple analysis, spike
calculations mist be performed using the
results of the sample designated as the
"original sample" (see Section 8.9). The
average of the duplicate results cannot be
used for the purpose of determining
percent recovery. NOTE: Samples
identified as field blanks cannot be used
for the spike sample analysis. EPA may
require that a specific sample be used for
the spike sample analysis.
8.8.3 Analyze an aliquot of the sample by the
ICP parameters for all elements listed in
Table 1 to determine the background
concentration of each element.
8.8.4 Using these concentrations, prepare a QC
spike standard containing the analytes.
The standard shall produce a concentration
in the sample of 1x - 5x the background
level determined above.. For not-detected
analytes, the spike shall be in the range
of 5x - 50x the detection limit.
8.8.5 Spike a second sanple aliquot with the QC
spike concentrate and analyze it to
determine the concentration in the sample
after spiking of each analyte.
8.8.6 Calculate the percent recovery of each
analyte as follows:
P = A ' B x 100
T
Where,
A = Concentration of element in the
sample after spiking.
B = Background concentration of each
element in the sample. NOTE: Uhen
B is less than the instrument
detection limit, use B=0 only for
the purpose of calculation.
T = Known true value of the spike.
8.8.7 The acceptable range for recovery of the
predigested spike is 75-125 percent for
all analytes. EPA will develop recovery
limits based on single or inter laboratory
data when sufficient data have been
accumulated. Report the result for each
analyte that falls within the 75-125
percent recovery limits.
8.8.8 If the recovery limit is not met for any
analyte, proceed as follows.
8.8.8.1 For ICP elements, repeat the test. If the
recovery is still outside the range, the
19
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instrunent conditions should be verified
by running the CCV. If the calibration
criteria are not met, the instrument
should be recalibrated and the spike
recovery test repeated. If after
recalibration, the spike recovery remains
outside of 75 - 125% limits, the sample
should be diluted by a factor of 10 and
the test repeated. Report and qualify the
results.
8.8.8.2 For AA elements, analyze the sample by the
method of standard addition (MSA) (Section
8.15). If the correlation coefficient
meets method requirements (Section
8.15.7), report and qualify the results.
If these specifications are not met,
dilute an aliquot of the original sample
by a factor of 10 and repeat the analysis
by MSA.
8.8.8.3 If correlation coefficient of the diluted
analysis meets specifications, report and
qualify the results. If these
specifications are not met, recalibrate
the instrument and repeat the analysis by
MSA on the diluted sample. If the
correlation coefficient specifications are
not met, report and qualify the results.
8.9 OupCicate Spike Sample Analysis (Matrix
Spike Duplicate)
8.9.1 Duplicate spike analyses (matrix spike
duplicate) shall be performed on 10% of
the samples analyzed, or at least one
duplicate analyses shall be performed for
each set or Episode of samples, whichever
is more frequent.
8.9.2 Repeat the spiking and analysis of a third
aliquot of the same sample as used for
determination of spike recovery (Section
8.8.5), using the same analysis scheme as
used for analysis of the sample. For
example, if an analyte determined by AA
required dilute MSA analysis in order to
meet the spike recovery limits, determine
that metal in the duplicate spike analysis
by dilute MSA analysis.
8.9.3 Samples identified as field blanks cannot
be used for duplicate spike sample
analysis. EPA may require that a specific
sample be used for duplicate spike sample
analysis.
8.9.A The acceptable range for precision of the
spike recovery is less than twenty percent
relative percent difference (<20% RPD) for
all analytes. EPA will develop precision
limits based on a single or inter-
laboratory data when sufficient data have
been accunulated. Report and qualify the
result for each analyte that fails the
RPD.
8.9.5 The relative percent differences (RPD) for
each component are calculated as follows:
RPD = lS ' °l x 100
(S + D)/2
Where,
RPD => Relative percent difference
S = First spike sample value (matrix
spike)
D = Second spike sample value
(matrix spike duplicate)
8.10 Laboratory Control Sample (LCS) Analysis
8.10.1 Laboratory control samples (Section 6.1.9)
must be analyzed for each analyte using
the same sample preparation technique,
analytical methods, and QA/QC procedures
as employed in sample analysis. An LCS
must be analyzed for each set or Episode
of samples or for each standard stock
batch.
8.10.2 If the percent recovery for the LCS falls
outside the control limits of 80-120%
(with the exception of Ag and Sb), the
analyses must be terminated, the problem
corrected, and the samples associated with
that LCS redigested and reanalyzed. For
Ag and Sb, qualify the results.
8.11 ICP Serial Dilution Analysis
8.11.1 For quantitative ICP analysis, prior to
reporting concentration data for the
analyte elements, analyze and report the
results of the ICP serial dilution
analysis. The ICP serial dilution
analysis must be performed on 10% of the
samples analyzed, or at least one serial
dilution analysis shall be performed for
each set or Episode of samples, whichever
is more frequent. NOTE: Samples
identified as field blanks cannot be used
for serial dilution analysis.
8.11.2 If the analyte concentration is
sufficiently high (minimally a factor of
50 above the instrumental detection limit
in the original sample), the serial
dilution (a five-fold dilution) must then
agree within 10% of the original
20
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determination after correction for
dilution. If the dilution analysis for
one or more analytes is not at or within
10%, a chemical or physical interference
effect must be suspected and the data for
all sample analyses associated with that
serial dilution must be flagged.
8.11.3 The percent differences for each component
are calculated as follows:
X Difference = I1 " Sl x 100
I
Uhere,
1 a Initial Sample Result
S = Serial Dilution Result (Instrunent
Reading x 5)
8.11.4 In the instance where there is more than
one serial dilution per sample set or
Episode, if one serial dilution result is
not within method specifications (see
Section 8.11.2), flag all samples in the
set or Episode that are associated with
that serial dilution.
8.12 Instrument Detection Limit (IDL)
Determination
8.12.1 Before any field samples are analyzed
under this method, the instrunent
detection limits (in ug/L) must be
determined for each instrunent used,
within 30 days of the start of analyses
under this method and at least quarterly
(every three calendar months), and must
meet the MLs specified in Table 9.
8.12.2 The instrument detection limits (in ug/L)
shall be determined by multiplying by
three, the average of the standard
deviations obtained on three
nonconsecutive days from the analysis of a
standard solution (each analyte in reagent
water) at a concentration 3-5x the
instrunent manufacturer's suggested IDL,
with seven consecutive measurements per
day. Each measurement must be performed
as though it were a separate analytical
sample (i.e., each measurement must be
followed by a rinse and/or any other
procedure normally performed between the
analysis of separate samples). IDL's must
be determined and reported for each
wavelength used in the analysis of the
sanples.
8.12.3 The quarterly determined IDL for an
instrument must always be used as the IDL
for that instrunent during that quarter.
If the instrument is adjusted in any way
that may affect the IDL, the IDL for that
instrunent must be redetermined and the
results submitted for use as the
established IDL for that instrunent for
the remainder of the quarter.
8.12.4 IDLs must be reported for each instrunent
used. If multiple AA instruments are used
for the analysis of an element within a
sample set or Episode, the highest IDL for
the AAs must be used for reporting
concentration values for that sample set.
The same reporting procedure must be used
for multiple ICPs.
8.13 Inter-element Corrections for ICP
8.13.1 Prior to the start of analysis under this
method and at least annually thereafter,
the ICP inter-element correction factors
must be determined. Correction factors
for spectral interference due to Al, Ca,
Fe, and Mg must be determined for all ICP
instruments at all wavelengths used for
each analyte reported by ICP. Correction
factors for spectral interference due to
analytes other than Al, Ca, Fe, and Mg
must be reported if they were applied.
8.13.2 If the instrument was adjusted in any way
that may affect the ICP interelement
correction factors, the factors must be
redetermined and the results submitted for
use.
8.14 Linear Range Analysis (LRA) -- For all
quantitative ICP analyses, a linear range
verification check standard must be
analyzed and reported quarterly (every
three calendar months) for each element
for each wavelength used. The standard
must be analyzed during a routine
analytical run performed under this
method. The analytically determined
concentration of this standard must be
within ±5X of the true value. This
concentration is the upper limit of the
ICP linear range beyond which results
should not be used without dilution of the
analytical sample.
8.15 Method of standard addition (MSA) -- All
GFAA elements must be analyzed by method
of standard addition in all samples.
8.15.1 The standard addition technique involves
preparing new standards in the sample
matrix by adding known amounts of standard
21
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to one or more aliquots of the processed
sample solution. This technique
compensates for a sample constituent that
enhances or depresses the analyte signal,
thus producing a different slope from that
of the calibration standards. It will not
correct for additive interferences which
cause a baseline shift. The simplest
version of this technique is the single-
addition method. The procedure is as
follows.
8.15.1.1 Two identical aliquots of the sample
solution, each of volume V^, are taken.
To the first (labeled A) is added a small
volume Vg of a standard analyte solution
of concentration C . To the second
s
(labeled B) is added the same volume V of
s
the solvent. The analytical signals of A
and B are measured and corrected for non-
ana I yte signals. The unknown sample
concentration Cx is calculated:
Cx = Ws
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9.1.1.3 Sample preservation is performed by the
sampler inmediately following sample
collection. The sample should be
preserved with nitric acid to pH of less
than 2.
9.1.1.4 Samples should be maintained at 4 °C (±2
°C) until analysis.
9.1.1.5 Sample analysis should be completed within
six months of sample collection.
9.1.2 Soil/sediment sample preservation
9.1.2.1 The preservation required for soil samples
is maintenance at 4 °C (±2 °C) until
analysis.
9.1.2.2 Sample analysis should be completed within
six months of sample collection.
9.2 Mercury Analysis by CVAA
9.2.1 Analysis of Mercury in Uater by Manual or
Automated CVAA
9.2.1.1 Until more conclusive data are obtained,
samples are preserved at the time of
collection by acidification with nitric
acid to a pH of 2 or lower.
9.2.1.2 Analysis for mercury should be completed
within 28 days after collection of the
sample.
9.2.2 Analysis of Mercury in Soil/Sediment by
Manual CVAA
9.2.2.1 Because of the extreme sensitivity of the
analytical procedure and the omnipresence
of mercury, care must be taken to avoid
extraneous contamination. Sampling
devices and sample containers should be
ascertained to be free of mercury; the
sample should not be exposed to any
condition in the laboratory that may
result in contact or air-borne mercury
contamination.
9.2.2.2 Refrigerate soil samples at 4 °C (+2 °C)
upon collection until analysis.
9.2.2.3 The sample should be analyzed without
drying. A separate percent solids
determination is required (Section
11.1.1).
9.2.2.4 Analysis should be completed within 28
days after sample collection.
10 PROCEDURES FOR SAMPLE PREPARATION AND
ANALYSIS
10.1 ICP and GFAA Spectroscopic Techniques
10.1.1 Uater Sample Preparation
10.1.1.1 Acid digestion procedure for GFAA -- Shake
sample and transfer 100 mL of well-mixed
sample to a 250-mL beaker, add 1 mL (1+1)
HNOj and 2 mL 30% HjOj to the sample.
Cover with watch glass or similar cover
and heat on a steam bath or hot plate for
2 hours at 95 °C or until sample volume is
reduced to between 25 and 50 mL, making
certain sample does not boil. Cool sample
and filter to remove insoluble material.
(NOTE: In place of filtering the sample,
after dilution and mixing the sample may
be centrifuged or allowed to settle by
gravity overnight to remove insoluble
material.) Adjust sample volume to 100 mL
with deionized distilled water. The
sample is now ready for analysis. NOTE:
If Sb is to be determined by furnace AA,
use the digestate prepared for ICP
analysis.
10.1.1.2 Acid digestion procedure for ICP analysis
-- Shake sample and transfer 100 mL of
well-mixed sample to a 250-mL beaker, add
2 mL (1*1) HNOj and 10 mL (1+1) HCl to the
sample. Cover with watch glass or similar
cover and heat on a steam bath or hot
plate for 2 hours at 95 °C or until sample
volune is reduced to between 25 and 50 mL,
making certain sample does not boil. Cool
sanple and filter to remove insoluble
material. (NOTE: In place of filtering
the sample, after dilution and mixing the
sanple may be centrifuged or allowed to
settle by gravity overnight to remove
insoluble material.) Adjust sample volune
to 100 mL with deionized distilled water.
The sample is now ready for analysis.
10.1.1.3 Sludge samples having less than 1% solids
should be treated by the above method.
Sludge samples having between 1 to 30%
solids should be diluted to less than 1%
solids and then treated by the above
method.
10.1.2 Soil Sample Preparation -- This method is
an acid digestion procedure used to
prepare soils, sediments, and sludge
samples containing more than 30% solids,
for analysis by GFAA or by ICP. A
representative 1 g (wet weight) sample is
digested in nitric acid and hydrogen
23
-------
peroxide. The digestate is then refluxed
with either nitric acid or hydrochloric
acid. Hydrochloric acid is used as the
final reflux acid for the furnace AA
analysis of Sb, the ICP analysis of Al,
Sb, Ba, Be, Ca, Cd, Cr, Co, Cu, Fe, Pb,
Mg, Mn, N1, K, Ag, Na, Tl, V and Zn.
Nitric acid is employed as the final
reflux acid for the furnace AA analysis of
As, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni,
Se, Ag, Tl, V, and Zn. A separate sample
shall be dried for a percent solids
determination (Section 11.1.1).
10.1.2.1 Mix the sample thoroughly to achieve homo-
geneity. For each digestion procedure,
weigh (to the nearest 0.01 g)- a 1.0 - 1.5
g portion of sample and transfer it to a
beaker.
10.1.2.2 Add 10 mL of 1:1 nitric acid (HNOj), mix
the slurry, and cover with a watch glass.
Heat the sample to 95 °C and reflux for 10
minutes without boiling. Allow the sample
to cool, add 5 mL of conc. HNO^, replace
the watch glass, and reflux for 30
minutes. Do not allow the volume to be
reduced to less than 5 mL, while
maintaining a covering of solution over
the bottom of the beaker.
10.1.2.3 After the second reflux step has been
completed and the sample has cooled, add 2
mL of deionized distilled water and 3 mL
of 30X HjOj. Return the beaker to the hot
plate for warming to start the peroxide
reaction. Care must be taken to ensure
that losses do not occur due to
excessively vigorous effervescence. Heat
until effervescence subsides, then cool
the beaker.
10.1.2.4 Continue to add 30% H^ in 1 mL aliquots
with warming until the effervescence is
minimal or until the general sample
appearance is unchanged. NOTE: Do not
add more than a total of 10 mL 30%
10.1.2.5 If the sample is being prepared for the
furnace AA analysis of Sb, or ICP analysis
of Al, Sb, Ba, Be, Ca, Cd, Cr, Co, Cu,
Fe, Pb, Mg, Mn, Ni, K, Ag, Na, Tl, V, and
Zn, add 5 mL of 1:1 HCl and 10 mL of
deionized distilled water, return the
covered beaker to the hot plate, and heat
for an additional 10 minutes. After
cooling, filter through Whatman No. 42
filter paper (or equivalent) and dilute to
100 mL with deionized distilled water.
(NOTE: In place of filtering the sample.
after dilution and mixing the sample may
be centrifuged or allowed to settle by
gravity overnight to remove insoluble
material.) The diluted sample has an
approximate acid concentration of 2.5%
(v/v) HCl and 5% (v/v) HN0-. Dilute the
digestate 1:1 (200 mL final volume) with
acidified water to maintain constant acid
strength. The sample is now ready for
analysis.
10.1.2.6 If the sample is being prepared for the
furnace analysis of As, Be, Cd, Cr, Co,
Cu, Fe, Pb, Mn, Ni, Se, Ag, Tl, V, and Zn,
continue heating the acid-peroxide
digestate until the volune has been
reduced to approximately 2 mL, add 10 mL
of deionized distilled water, and warm the
mixture. After cooling, filter through
Whatman No. 42 filter paper (or
equivalent) and dilute to 100 mL with
deionized distilled water. (NOTE: In
place of filtering the sample, after
dilution and mixing the sample may be
centrifuged or allowed to settle by
gravity overnight to remove insoluble
material.) The diluted digestate solution
contains approximately 2% (v/v) HNOj.
Dilute the digestate 1:1 (200 mL final
volume) with acidified water to maintain
constant acid strength. For analysis,
withdraw aliquots of appropriate volume,
and add any required reagent or matrix
modifier. The sample is now ready for
analysis.
10.1.3 Sample Analysis
10.1.3.1 Initiate the appropriate operating
configuration of the computer.
10.1.3.2 Profile and calibrate the instrument
according to instrunent manufacturer's
recommended procedures, using mixed
calibration standard solutions such as
those described in Section 6.1.4. Flush
the system with the calibration blank
(Section 6.1.8.1) between each standard.
NOTE: For boron concentrations greater
than 500 ug/L, extended flush times of 1 -
2 minutes may be required.
10.1.3.3 Begin the sample run, flushing the system
with the calibration blank solution
(Section 6.1.S.1) between each sample.
(See NOTE in Section 10.1.3.2.) Analyze
the CCV standard (Section 6.1.6) and the
calibration blank (Section 6.1.8.1)
following each 10 analytical sairples.
24
-------
10.1.3.4 A minimum of two replicate exposures are
required for standardization and for all
QC and sample analyses, except during MSA.
The average result of the multiple
exposures for the standardization and all
QC and sample analyses shall be used.
10.2 Semiquantitative Screen of 42 Elements by
ICP
10.2.1 All element files should be set up with
the narrowest possible survey and peak
windows. Wherever possible, automatic or
manual background correction for each
element should be employed to compensate
for interferences.
10.2.2 Uavelength calibration standards should be
run as many times as needed to bring all
analytes within the specified survey
window. This may require as many as five
replicate readings on the uavelength
standard. The lower threshold limit (LTL)
for each element is established by
analyzing each analyte at a level of twice
the expected LTL in seven replicates. The
LTL is the value obtained by multiplying
three times the standard deviation of the
replicate readings.
10.2.3 Following wavelength calibration,
instrunent calibration standards and
blanks are run. The system should be
flushed with the calibration blank
solution between readings.
10.2.4 Analysis of solutions following
calibration can be performed using single
readings. Uavelength profiles should be
stored on a magnetic device for future
reference.
10.3 Analysis of Mercury in Water by Manual
Cold Vapor Technique
10.3.1 Transfer 100 mL of sample, or a sample
aliquot diluted to 100 mL, containing not
more than 1.0 ug of mercury, to a 300 mL
BOO bottle. Add 5 mL of sulfuric acid
(Section 6.4.1) and 2.S mL of conc. nitric
acid (Section 6.4.2), mixing after each
addition. Add 15 mL of potassiun
permanganate solution (Section 6.4.5) to
each sample bottle. The same amount of
KMnO^ added to the samples should be
present in standards and blanks. (NOTE:
For sewage samples additional permanganate
may be required.) Shake and add
additional portions of potassiun
permanganate solution, if necessary, until
the purple color persists for at least 15
minutes. Add 8 mL of potassiun persulfate
(Section 6.4.6) to each bottle and heat
for 2 hours in a water bath at 95 °C
10.3.2 Cool and add 6 mL of sodium chloride-
hydroxylamine sulfate (Section 6.4.4) to
reduce the excess permanganate (NOTE: Add
reductant in 6 mL increments until KMnO,
is completely reduced.) Purge the head
space in the BOO bottle for at least 1
minute, add 5 mL of stannous sulfate
(Section 6.4.3), and inmediately attach
the bottle to the aeration apparatus.
Continue as described under Section 7.2.1.
10.3.3 Sludge samples having less than IX solids
should be treated by the above method.
Whereas, sludge samples having between 1
to 30X solids should be diluted to less
than 1X solids and then treated by the
above method.
10.4 Analysis of Mercury in Water by Automated
Cold Vapor Technique
10.4.1 Set up manifold as shown in Figure 3.
10.4.2 Feeding all the reagents through the
system, with acid wash solution (Section
6.5.2.1) through the sample line, adjust
heating bath to 105 °C.
10.4.3 Turn on atomic absorption spectrophoto-
meter, adjust instrunent settings as
recommended by the manufacturer, align
absorption cell in light path for maximum
transmittance, and place heat lamp (if
used) directly over absorption cell.
10.4.4 Arrange working mercury standards from 0.2
to 20.0 ug Hg/L in sampler and start
sampling. Complete loading of sample tray
with unknown samples.
10.4.5 Prepare standard curve by plotting peak
height of processed standards against
concentration values. Determine
concentration of samples by comparing
sample peak height with standard curve.
10.4.6 After the analysis is complete put all
lines except the HjSO^ line in distilled
water to wash out system. After flushing
the system, wash out the H^SO^ line. Also
flush the coils in the high temperature
heating bath by punping stannous sulfate
(Section 6.5.3) through the sample lines,
followed by deionized distilled water.
This will prevent build-up of oxides of
25
-------
• • Teflon SCRUBBER
••• Glass
FIGURE 3 Mercury Manifold Setup
26
-------
10.4.7
10.5
10.5.1
manganese. Because of the toxic nature of
mercury vapor, precaution must be taken to
avoid its inhalation. Venting the mercury
vapor into an exhaust hood or passing the
vapor through some absorbing media such
as, equal volumes of 0.1 N KMnO, (Section
6.5.6) and 10X HjSO^ (Section 6.5.1.2), or
0.25X iodine in a 3X KI solution,
isrecommended. A specially treated
charcoal that will absorb mercury vapor is
also available.
For treatment of
Section 10.3.3.
sludge samples, see
10.5.2
Analysis of Mercury in Soil/Sediment by
Manual Cold Vapor Technique
Ueigh a representative 0.2 g portion of
wet sample and place in the bottom of a
BOO bottle. Add 5 ml of sulfuric acid
(Section 6.6.1) and 2.5 mL of conc. nitric
acid (6.6.2), mixing after each addition.
Heat two minutes in a water bath at 95 °C.
Cool, add 50 mL distilled water, 15 mL
potassium permanganate solution (Section
6.6.5), and 8 mL of potassium persulfate
solution (Section 6.6.6) to each sample
bottle. Mix thoroughly and place in the
water bath for 30 minutes at 95 °C. Cool
and add 6 mL of sodium chloride-
hydroxylamine sulfate (Section 6.6.4) to
reduce the excess permanganate. Add 55 mL
of distilled water. Treating each bottle
individually, purge the head space of the
sample bottle for at least one minute, add
5 mL of stannous sulfate (Section 6.6.3),
and immediately attach the bottle to the
aeration apparatus. Continue as described
mder Section 7.3.1.
An alternate digestion procedure employing
an autoclave may also be used. In this
method, add 5 mL conc. H.SO^ and 2 mL
conc. HNOj to the 0.2 g of sample. Then
add 5 mL saturated KMnO^ solution and 8 mL
potassium persulfate solution and cover
the bottle with a piece of aluminum foil.
Autoclave the sample at 121 °C and 15 psi
for 15 minutes. Cool, make up to a volume
of 100 mL with distilled water, and add 6
mL of sodiun chloride-hydroxylamine
sulfate solution (Section 6.6.4) to reduce
the excess permanganate. Purge the
headspace of the sample bottle for at
least 1 minute and continue as described
under Section 7.3.1.
11 QUANTITATION DETERMINATION
11.1 ICP and GFAA Spectroscopic Techniques
11.1.1 Analytical results for water samples are
expressed in ug/L; for soil samples,
analytical results are expressed as mg/kg
on a dry weight basis. Therefore, a
determination of percent solids is
required for soils, sediments, and sludge
samples containing greater than 30X
solids, as follows.
11.1.1.1 Immediately following the weighing of the
sample to be processed for analysis (see
Section 10), add 5-10 g of sample to a
tared weighing dish. Ueigh and record the
weight to the nearest 0.01 g.
11.1.1.2 Place weighing dish plus sample, with the
cover tipped to allow for moisture escape,
in a drying oven maintained at 103-105 °C.
NOTE: Sample handling and drying should
be conducted in a well-ventilated area.
11.1.1.3 Dry the sample overnight (12-24 hours),
but no longer than 24 hours. If dried
less than 12 hours, it must be docunented
that constant weight was attained. Remove
the sample from the oven and cool in a
dessicator with the weighing dish cover in
place before weighing. Ueigh and record
weight to nearest 0.01 g. Do not analyze
the dried sample.
NOTE: Drying time is defined as the
elapsed time in the oven. Therefore, time
in and out of the oven should be recorded
to document the 12-hour drying time
minimun. In the event it is necessary to
demonstrate the attainment of constant
weight, data must be recorded for a
minimum of two repetitive weigh/dry/
dessicate/weigh cycles with a minimun of
one-hour drying time in each cycle.
Constant weight is defined as a loss in
weight of no greater than 0.01 g between
the start weight and final weight of the
last cycle.
11.1.1.4 Calculate percent solids by the formula
below. This value will be used for
calculating analyte concentration on a dry
weight basis.
X Solids
Sample Dry Ueight
Sample Uet Ueight
100
10.5.3 Sludge samples having more than 30X solids
should be treated by this method.
11.1.2 The concentrations determined in the
digest are to be reported on the basis of
27
-------
11.1.2.1
11.1.3
11.1.4
11.1.5
the dry weight of the sample for
soil/sediment samples and sludge samples
containing greater than 30% solids.
C x V
Concentration (dry wt) (mg/kg) = u _
11.2.3
Uhere,
C
V
Concentration (mg/L)
Final volume in liters after sample
preparation
Weight in kg of wet sample
X Solids/100
For aqueous samples and sludge samples
containing less than 30% solids, the
concentration of the elements in the
digest can determined as follows:
Concentration (ug/L)
C x V,
I
11.2
11.2.1
11.2.2
Uhere,
C = Concentration (ug/L)
Vp = Final volume in liters after
sample preparation
Vj = Volune in liters of the sample
digested.
Preparation (reagent) blanks should be
treated as specified in Section 10.
If dilutions were performed, the
appropriate factor must be applied to
sample values.
Report results for semiquantitative ICP
screen of 42 elements in ug/L or mg/kg,
depending on the matrix. Samples are
semiquantified by comparing each analyte
result to the established LTL for that
analyte. All "peak offsets" or similar
designations reported by ICP should be
searched through stored spectrum files or
the data confirmed through sample spikes
before reporting.
Analysis of Mercury in Uater by Manual and
Automated Cold Vapor Technique
Determine the peak height of the unknown
from the chart and read the mercury value
from the standard curve.
Calculate the mercury concentration in the
sample by the formula:
ug Hg/L
ug Hg in aliquot
volune of aliquot in mL~
11.3
11.3.1
11.3.2
Report mercury concentrations as follows:
below 0.20 ug/L,to 0.20 U; between 0.20
and 10.0 ug/L, to two significant figures;
equal to or above 10.0 ug/L, to three
significant figures.
Analysis of Mercury in Soil/Sediments by
Manual Cold Vapor Technique
Measure the height of the unknown peak
from the chart and read the mercury value
from the standard curve.
Calculate the mercury concentration in the
sample by the formula:
ug Hg/g
ug Hg in the aliquot
x 1000
wt of the aliquot in gms
(based upon dry weight of the sample)
11.3.3 Report mercury concentrations for
soil/sediment samples converted to mits
of mg/kg. The sample result or the
detection limit for each sample must be
corrected for sample weight and percent
solids before reporting.
12 ANALYSIS OF COMPLEX SAMPLES
12.1 Some samples may contain high levels
(>1500 mg/L) of the compounds of interest,
interfering compounds, and/or polymeric
materials. These may lead to inaccuracies
in the determination of trace elements.
12.2. Physical, chemical, and/or spectral
interference effects may arise. These
interferences can be overcome by dilution
of the sample, matrix matching, varying
the temperature or by employing the Method
of Standard Addition. These effects are
described in Section 3.
The acceptable range for recovery of the
predigested spike is 75-125 percent for
all analytes. If any analyte falls
outside the OC limits, proceed as
described in Section 8.8.
13 METHOD PERFORMANCE
13.1 In an EPA round robin study, seven
laboratories applied the ICP technique to
acid-distilled water matrices that had
been dosed with various metal
concentrations. Table 12 lists the true
values, the mean reported values, and the
mean percent relative standard deviations
from this study.
12.3
28
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13.2 The precision data obtainable for the
electrothermal atanization AA method is
given in Table 13.
13.3 The precision data for CVAA technique for
analysis of mercury is given in Table 14.
14 GLOSSARY OF TERMS
14.1 Calibration blank -- A volume of deionized
distilled water acidified with HNQj and
HCl used in establishing the analytical
curve.
14.2 Calibration standards -- A series of known
standard solutions used by the analyst for
calibration of the instrument (i.e.,
preparation of the analytical curve).
14.3 Continuing calibration verification (CCV)
standard solutions -- A multi-element
standard of known concentrations prepared
by the laboratory to monitor and verify
instrument performance on a daily basis.
14.4 Dissolved elements -- Those elements which
will pass through a 0.45 um membrane
filter.
14.5 Initial calibration verification (ICV)
standard solutions -- A solution obtained
from an outside source having known
concentration values, used to verify the
calibration standards.
14.6 Instrunental detection limits (IDL) --
Determined by multiplying by three the
standard deviation obtained for the
analysis of a standard solution (each
analyte in reagent water) at a
concentration of 3-5x IDL on three
nonconsecutive days, with seven
consecutive measurements per day.
14.7 Interference check sample (ICS) -• A
solution containing both interfering and
analyte elements of known concentration,
used to verify background and inter-
element correction factors.
14.8 Laboratory control sample -- A control
sample of known composition. Aqueous and
solid laboratory control samples are
analyzed using the same sample
preparation, reagents, and analysis
methods employed for the analytical
samples.
14.9 Linear range -- The concentration range
over which the analytical curve remains
linear.
14.10 Lower threshold limit (LTL) -- Based on
signal-to-noise ration of 2:1 for each
element, expressed as mg/L. Levels lower
than LTL are considered "not detected."
The LTL for each element is highly
dependent on sample matrix.
14.1 Method of Standard Addition (MSA) -- The
standard addition technique involves the
use of the unknown and the unknown-plus-a-
known amount of standard by adding known
amounts of standard to one or more
aliquots of the processed sample solution
The MSA procedure is described in Section
8.15.
14.12 Mininun level (ML) -- The mininun level is
defined as the minimun concentration of a
substance that can be measured and
reported with 99% confidence that the
value is above zero. The laboratory is
required to achieve the ML listed for each
element in Table 11.
14.13 Preparation (reagent) blank -- A volume of
deionized distilled water containing the
same acid matrix as the calibration
standards, that is carried through the
entire analytical scheme.
14.14 Sensitivity -- The slope of the analytical
curve, i.e., functional relationship
between emission intensity or absorption
and concentration.
14.15 Serial dilution analysis -- A five-fold
dilution analysis used to establish a
chemical or physical interference effect.
14.16 Soil samples -- Soils, sediments, and
sludge samples containing more than 30X
solids.
14.17 Suspended elements -- Those elements which
are retained by a 0.45 um membrane filter.
14.18 Total elements -- The concentration
determined on an unfiltered sample
following vigorous digestion.
14.19 Water samples -- Aqueous samples and
sludge samples containing 30% or less
solids which are diluted and treated as
water samples.
29
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15 BIBLIOGRAPHY
15.1 Annual Book of ASTM Standards, Part 31,
"Water," Standard D3223-73 (1976).
15.2 "Carcinogens - Working With Carcinogens,"
Department of Health, Education, and
Welfare, Public Health Service, Center for
Disease Control, National Institute for
Occupational Safety and Health,
PiAlication No. 77-206, Aug. 1977.
15.3 Handbook for Analytical Quality Control in
Water and Wastewater Laboratories, EPA-
600/4-79-019.
15.4 "Inductively Coupled Plasma-Atomic
Emission Spectrometric Method of Trace
Elements Analysis of Water and Waste",
Method 200.7 modified by CLP Inorganic
Data/Protocol Review Committee; original
method by Theodore D. Martin,
EMSL/Cincinnati.
15.5 "Interim Methods for the Sampling and
Analysis of Priority Pollutants in
Sediments and Fish Tissue," USEPA
Environmental Monitoring and Support
Laboratory, Cincinnati, Ohio, August 1977,
revised October 1980.
15.6 Methods for Chemical Analysis of Water and
Wastes, EPA-600/4-79-020.
15.7 "OSHA Safety and Health Standards, General
Industry," (29 CFR 1910), Occupational
Safety and Health Administration, OSHA
2206, (Revised, January 1976).
15.8 "Safety in Academic Chemistry
Laboratories," American Chemical Society
Publications, Committee on Chemical
Safety, 3rd Edition, 1979.
15.9 Standard Methods for the Examination of
Water and Wastewater, 14th Edition, p. 156
(1975).
15.10 Statement of Work for Inorganics Analysis,
Multi-Media, Hulti-Concentration, SOW No.
788, USEPA Contract Laboratory Program
(July, 1988).
15.11 Bishop, J. N., "Mercury in Sediments,"
Ontario Water Resources Comm., Toronto,
Ontario, Canada, 1971.
15.12 Brandenberger, H. and Bader, H., "The
Determination of Nanogram Levels of
Mercury in Solution by a FlameIess Atomic
Absorption Technique," Atomic Absorption
Newsletter 6, 101 (1967).
15.13 Brandenberger, H. and Bader, H., "The
Determination of Mercury by FlameIess
Atomic Absorption II, A Static Vapor
Method," Atomic Absorption Newsletter 7:53
(1968).
15.14 Garbarino, J.R. and Taylor, H.E., "An
Inductively-Coupled Plasma Atomic Emission
Spectrometric Method for Routine Water
Quality Testing," Applied Spectroscopy 33,
Ho. 3 (1979).
15.15 Goulden, P.D. and Afghan, B.K. "An
Automated Method for Determining Mercury
in Water," Technicon, Adv. in Auto. Analy.
2, p. 317 (1970).
15.16 Hatch, W.R. and Ott, W.L., "Determination
of Sub-Microgram Quantities of Mercury by
Atomic Absorption Specrophotometry," Anal.
Chem. 40, 2085 (1968).
15.17 Kopp, J.F., Longbottom, M.C. and Lobring,
L.B., "Cold Vapor Method for Determining
Mercury," AWWA, vol. 64, p. 20, Jan. 1972.
15.18 Salma, M., personal commrucation, EPA
Cal/Nev. Basin Office, Almeda, California.
15.19 Wallace R.A., Fulkerson, W., Shults, W.D.,
and Lyon, W.S., "Mercury in the
Environment-The Human Element," Oak Ridge
National Laboratory, ORNL/NSF-EP-1, p. 31,
(January, 1971).
15.20 Winefordner, J.D., "Trace Analysis:
Spectroscopic Methods for Elements,"
Chemical Analysis, Vol. 46, pp. 41-42.
15.21 Uinge, R.K., V.J. Peterson, and V.A.
Fassel, "Inductively Coupled Plasma-Atomic
Emission Spectroscopy Prominent Lines,"
EPA-600/4-79-017.
30
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Table 1
RECOMMENDED WAVELENGTHS AND ESTIMATED
INSTRUMENTAL DETECTION LIMITS FOR ELEMENTS
ANALYZED BY ICP
Element
Wavelength (1)
ran
Estimated
Detection
Limit (2)
ug/L
Aluminum
308.215
45
Antimony
206.833
32
Arsenic
193.696
53
Barium
45S.403
2
Beryllium
313.042
0.3
Boron
249.773
5
Cadmium
226.502
4
Calcium
317.933
10
Chromium
267.716
7
Cobalt
228.616
7
Copper
324.754
6
Iron
259.940
7
Lead
220.353
42
Magnes ium
279.079
30
Manganese
257.610
2
Molybdenum
202.030
8
Nickel
231.604
15
Selenium
196.026
75
SiIver
328.068
7
Sodiun
588.995
29
Thai I inn
190.864
40
Tin
189.989 (3)
30
Titaniun
334.941
3
Vanadium
292.402
8
Yttrium
371.030
2.5
Zinc
213.856
2
(1) These wavelengths are recommended because of
their sensitivity and overall acceptance. Other
wavelengths may be substituted if they can
provide the needed sensitivity and are treated
with the same corrective techniques for spectral
interference (see Section 3.1.1). The use of
alternate wavelengths should be reported (in rm)
with the sample data.
(2) Estimated detection limits are taken from
"Inductively Coupled Plasma-Atomic Emission
Spectroscopy-Proniinent Lines," EPA-600/4-79-017.
They are given as a guide for an instrumental
limit. The actual method detection limits are
sample dependent and may vary as the sample
matrix varies.
(3) Nitrogen purge used at this wavelength.
Table 2
RECOMMENDED WAVELENGTHS, ESTIMATED INSTRUMENTAL
DETECTION LIMITS, AND OPTIMUM CONCENTRATION RANGE FOR
ELEMENTS ANALYZED BY AA SPECTROSCOPY (1)
Element
Wavelength
(ran)
Estimated
Detection
Limit (2)
(ug/L)
Opt i mum
Concentration
Range (2)
(ug/L)
GFAA
Antimony
217.6
3
20-300
Arsenic
193.7
1
5-100
Lead
283.3(3)
1
5-100
Selenium
196.0
2
5-100
Thallium
276.8
1
5-100
CVAA
Mercury
253.7
0.2
0.2-20
(1) Values are taken from Methods 204.2 (Sb), 206.2
(As), 210.2 (Be), 213.2 (Cd), 218.2 (Cr), 239.2
(Pb), 270.2 (Se), 272.2 (Ag), 279.2 (Tl),
"Methods for Chemical Analysis of Water and
Wastes" (EPA-600/4-79-020), Metals-4.
(2) Concentration values and instrument conditions
given are for a Perkin-Elmer HGA-2100, based on
the use of a 20 uL injection, continous flow
purge gas, and non-pyrolytic graphite, and are
to be used as guidelines only. Smaller size
furnace devices or those employing faster rates
of atomization can be operated using lower
atomization temperatures for shorter time
periods than these recommended settings.
(3) The line at 217.0 nm is more intense, and is
recofimended for instruments with background
correction.
31
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Table 3
RECOMMENDED INSTRUMENTAL PARAMETERS FOR ANALYSIS OF TRACE ELEMENTS BY GFAA SPECTROSCOPY (1)
Drying
Ash i ng
Atomizing
Element
Time and Temperature
Time and Temperature
Time and Temperature
Purge Gas
(sec)
(°C)
(sec)
(°C)
(sec)
CC)
Atmosphere
Antimony
30
125
30
800
10
2700
Argon (2)
Arsenic
30
125
30
1100
10
2700
Argon
Lead
30
125
30
500
10
2700
Argon
Selenium
30
125
30
1200
10
2700
Argon
Thalliun
30
125
30
400
10
2400
Argon (2)
(1) Other operating parameters should be set as specified by the particular instrument manufacturer.
(2) Nitrogen may be substituted as the purge gas (see Section 3.2.2).
32
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Table 4
ICP SCREEN ELEMENTS, WAVELENGTHS, AND LOWER THRESHOLD
LIMITS
Element
Symbol
Wavelength (1)
LTL (2)
(mg/L)
B i smuth
Bi
396.152
0.1
Ceriun
Ce
413.765
1
Dysprosium
Dy
353.170
0.1
Erbiun
Er
349.910
0.1
Europium
Eu
381.967
0.1
Gadoliniun
Gd
342.247
0.5
Gallium
Ga
294.364
0.5
Germanium
Ge
265.118
0.5
Gold
Au
242.765
1
Hafnium
Hf
277.336
1
Holmium
Ho
345.600
0.5
Indiun
In
230.606
1
Iodine
I
183.038
1
IridiLn
Ir
224.268
1
Lanthanum
La
379.478
0.1
Lithium
Li
670.781
0.1
Lutetium
Lu
261.542
0.1
Neodymiun
Nd
309.418
0.5
Niobium
Nb
401.225
1
Osmium
Os
228.226
0.1
Palladium
Pd
340.458
0.5
Phosphorus
P
213.618
1
Platinum
Pt
214.423
1
Potassium
K
766.490
1
Praseodymiun
Pr
390.844
1
Rhenium
Re
221.426
1
Rhodium
Rh
233.477
1
Ruthenium
Ru
240.272
1
Samarium
Sm
359.260
0.5
Scandium
Sc
361.384
0.1
S iIicon
Si
251.611
0.1
Strontium
Sr
407.771
0.1
Sulfur
S
180.731
1
Tantalum
Ta
226.230
0.5
Tellurium
Te
214.281
1
Terbiun
Tb
350.917
0.5
Thorium
Th
283.730
1
Thulium
Tm
313.126
0.5
Tungsten
W
207.911
1
Uranium
U
385.958
1
Ytterbium
Yb
328.937
0.1
Zirconium
Zr
343.823
0.1
(1) Wavelength: Most sensitive line for analysis.
Line choice is dependent on sample matrix. Use
of secondary lines is necessary for some elements
for spectral interference confirmation.
(2) LTL: Lower Threshold Limit. Based upon signal-
to-noise ratio for each element; expressed as
mg/L. Lower levels would be recorded as ND. The
LTL for each analyte is highly dependent upon
sample matrix.
33
-------
Table 5
EXAMPLE OF ANALYTE CONCENTRATION EQUIVALENTS (MG/L) ARISING FROM INTERFERENTS AT THE 100 MG/L LEVEL
Element
Wavelength
(nm)
Al Ca
Cr
Cu
Fe
Hg
Mn
Hi
Ti
V
Aluninum
308.215
..
--
--
--
0.21
--
1.4
Antimony
206.833
0.47 --
2.9
0.08
--
--
.25
0.45
Arsenic
193.696
1.3
0.44
--
--
--
--
1.1
Barium
455.403
--
--
--
--
--
--
--
Berylliun
313.042
••
--
--
--
--
0.04
0.05
Boron
249.773
0.04 --
--
0.32
--
--
--
--
Cadnium
226.502
--
--
0.03
--
--
0.02
--
--
Calcium
317.933
..
0.08
0.01
0.01
0.04
0.03
0.03
Chromium
267.716
..
--
0.003
--
0.04
--
0.04
Cobalt
228.616
..
0.03
0.005
--
--
0.03
0.15
--
Copper
324.754
..
--
0.003
--
--
0.05
0.02
Iron
259.940
..
--
--
--
0.12
--
--
Lead
220.353
0.17 --
--
--
--
--
--
--
Magnesium
279.079
0.02
0.11
0.13
--
0.25
0.07
0.12
Manganese
257.610
0.005 --
0.01
0.002
0.002
--
--
--
Molybdenum
202.030
0.05 --
--
0.03
--
--
--
--
Nickel
231.604
..
--
--
--
--
--
--
Selenium
196.026
0.23 --
--
0.09
--
--
--
--
Si I icon
288.158
..
0.07
--
--
--
--
0.01
Sodium
588.995
..
--
--
--
--
0.08
--
Thallium
190.864
0.30 --
--
--
--
--
--
--
Vanadium
292.402
..
0.05
--
0.005
--
--
--
0.02
--
Zinc
213.856
..
--
0.14
--
--
--
0.29
--
--
34
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Table 6
ANALYTE AND INTERFERENT ELEMENTAL. CONCENTRATIONS USED
FOR INTERFERENCE MEASUREMENTS IN TABLE 5
Analytes
mg/L
Interferents
mg/L
Aluninum
10
Aluminun
1000
Antimony
10
Calcium
1000
Arsenic
10
Chromiun
200
Barium
1
Copper
200
Beryllium
1
Iron
1000
Boron
10
Magnesium
1000
Cadmiun
10
Manganese
200
Calcium
1
Nickel
200
Chromiun
1
Titaniun
200
Cobalt
1
Vanadium
200
Copper
1
Iron
1
Lead
10
Magnesium
1
Manganese
1
Molybdenum
10
Nickel
10
Selenium
10
Silicon
1
Sodium
10
Thallium
10
Vanadiun
1
Zinc
10
Table 7
WORKING STANDARD CONCENTRATIONS
Element
Symbol
Working
Standard (1)
(mg/L)
Bismuth
Bi
1.0
Cerium
Ce
1.0
Dysprosium
0y
1.0
Erbium
Er
1.0
Europium
Eu
1.0
Gadolinium
Gd
1.0
Galliun
Ga
1.0
Germanium
Ge
10.0
Gold
Au
10.0
Hafnium
Hf
10.0
Holmiun
Ho
10.0
Indiun
In
10.0
Iodine
I
10.0
Iridium
Ir
10.0
Lanthanum
La
1.0
Lithium
Li
1.0
Lutetium
Lu
1.0
Neodymiun
Nd
1.0
Niobiun
Nb
10.0
Osmium
Os
10.0
Palladium
Pd
1.0
Phosphorus
P
10.0
Platinum
Pt
10.0
Potassium
K
150.0
Praseodymium
Pr
10.0
Rheniun
Re
10.0
Rhodium
Rh
10.0
Ruthenium
Ru
10.0
Samarium
Sm
1.0
Scandiun
Sc
1.0
Silicon
Si
1.0
Strontium
Sr
1.0
Sulfur
S
10.0
Tantalum
Ta
1.0
Telluriun
Te
10.0
Terbium
Tb
1.0
Thoriun
Th
10.0
Thulium
Tm
1.0
Tungsten
W
1.0
Uraniun
U
10.0
Ytterbium
Yb
1.0
Zirconiun
Zr
1.0
(1) Working Standard: For each 1 mg/L of final
concentration needed, pipette 1 mL of stock
solution and dilute to 1 L final volume. For
example, for a 10 mg/L final concentration,
pipette 10.0 mL of stock solution.
35
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Table 8
QC SPECIFICATIONS FOR ANALYSIS OF PRECISION AND
ACCURACY STANDARDS (1)
I CP Spectroscopy GFAA Spectroscopy
Mean Mean
Element (2) X RSD (3) Element (2) X RSD (4)
Aluminum
17.2
Arsenic (5) 12.83
Arsenic
15.83
Lead 2.73
Beryllium
70.07
Selenium (5) 9.7
Cachiium
14.67
Chromiun
8.37
Cobalt
11.7
Copper
17.67
Iron
8
Lead
20.67
Manganese
4.23
Nickel
10.27
Selenium
24.07
Vanadiim
1.93
Zinc
20
(1) Acceptable range of percent recovery for all
elements is 75-125X. As more data becomes
available, these limits will be re-evaluated.
(2) Other elements will be added as data becomes
available to EPA.
(3) Values derived from 21 determinations.
(4) Values derived from 30 determinations, except
for Pb. A total of 36 determinations were made
for Pb.
(5) Automated sample injection.
Table 9
MINIMUM LEVELS (ML) OF DETECTION
ICP
ML
AA
ML
Analytes
(ug/L)
Analytes
(ug/L)
Aluminum
200
Antimony
20
Bar inn
200
Arsenic
10
Beryllium
5
Lead
5
Boron
10
Selenium
5
Cadmium
5
Thallium
10
Calciun
5000
Mercury
0.2
Chromiun
10
Cobalt
50
Copper
25
Iron
100
Magnesium
5000
Manganese
15
Molybdenum
10
Nickel
40
SiIver
10
Sod inn
5000
Tin
30
Titanium
5
Vanadium
50
Yttriun
5
Zinc
20
Table 10
INITIAL AND CONTINUING CALIBRATION VERIFICATION
CONTROL LIMITS
Analytical Inorganic X of True Value (EPA Set)
Method Species Low Limit High Limit
ICP (1)/AA Metals 90 110
Cold Vapor AA Mercury 80 120
(1) Limits apply to quantitative ICP and semiquanti-
tative ICP screen of 42 elements.
Table 11
ANALYTE AND INTERFERENT ELEMENTAL CONCENTRATIONS USED
FOR ICP INTERFERENCE CHECK SAMPLE
Analytes
mg/L
Interferents
mg/L
Barium
0.5
Aluminum
500
Beryllium
0.5
Calcium
500
Cadmium
1.0
Iron
200
Chromium
0.5
Magnes i urn
500
Cobalt
0.5
Copper
0.5
Lead
1.0
Manganese
0.5
Nickel
1.0
SiIver
1.0
Vanadium
0.5
Zinc
1.0
36
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Table 12
ICP PRECISION AND ACCURACY DATA (1)
Sample #1 Sample #2 Sample #3
Element
True
Value
(ug/L)
Mean
Reported
Value
(ug/L)
Mean
Percent
RSD
True
Value
(ug/L)
Mean
Reported
Value
(ug/L)
Mean
Percent
RSD
True
Value
(ug/L)
Mean
Reported
Value
(ug/L)
Mean
Percent
RSD
Aluminum
700
696
5.6
60
62
33
160
161
13
Arsenic
200
208
7.5
22
19
23
60
63
17
Beryllium
750
733
6.2
20
20
9.8
180
176
5.2
Cadmium
50
48
12
2.5
2.9
16
14
13
16
Chromium
150
149
3.8
10
10
18
50
50
3.3
Cobalt
500
512
10
20
20
4.1
120
108
21
Copper
250
235
5.1
11
11
40
70
67
7.9
Iron
600
594
3.0
20
19
15
180
178
6.0
Lead
250
236
16
24
30
32
80
80
14
Manganese
350
345
2.7
15
15
6.7
100
99
3.3
Nickel
250
245
5.8
30
28
11
60
55
14
Selenium
40
32
21.9
6
8.5
42
10
8.5
8.3
Vanadium
750
749
1.8
70
69
2.9
170
169
1.1
Zinc
200
201
5.6
16
19
45
80
82
9.4
(1) Not all elements were analyzed by all laboratories.
Table 13
PRECISION DATA FOR ELECTROTHERMAL ATOMIZATION METHODS (1)
Element (2)
Wavelength
(nm)
Sample
Size
(uL)
No. of
Replicate
Determinations
Mean
Concentration
(ug/L)
Relative
Standard
Deviation
Arsenic (3)
193.7
50
10
12.5
17.6
50
10
28.4
13.7
50
10
58.4
7.2
Lead
217.0
25
12
36.6
3.8
25
12
103
2.9
25
12
161
1.5
Selenium (3)
196.0
50
10
12.5
17.6
50
10
29.6
5.6
50
10
55.8
5.9
(1) Values taken from "Standard Methods for the Examination of Water and Wastewater," 16th edition, p 179
(1985).
(2) Other elements will be added as data becomes available to EPA.
(3) Automated sanple injection.
37
-------
PRECISION DATA FOR
Table 14
CVAA TECHNIQUE FOR
ANALYSIS OF MERCURY (1)
Relative
Metal
Standard
Relative
Number of
Metal
Concentration
Deviation
Error
Participants
(Dissolved)
(ug/L)
<%>
<%>
Inorganic
0.34
0.077
21
23
4.2
0.56
14.4
21
Organic
4.2
0.36
8.4
21
(1) Data from Kopp, J.F., H.C. Longbottom, and L. B. Lobring, 1972, "Cold Vapour Method for Determining
Mercury," J. Amer. Uater Works Ass. 64:20, for distilled water samples.
38
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