ASTM D5086-01(2008)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D5086 − 01(Reapproved 2008)
Standard Test Method for
Determination of Calcium, Magnesium, Potassium, and
Sodium in Atmospheric Wet Deposition by Flame Atomic
Absorption Spectrophotometry
This standard is issued under the fixed designation D5086; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method is applicable to the determination of
D883 Terminology Relating to Plastics
calcium, magnesium, potassium, and sodium in atmospheric
D1129 Terminology Relating to Water
wet deposition (rain, snow, sleet, and hail) by flame atomic
D1193 Specification for Reagent Water
absorption spectrophotometry (FAAS). (1)
D1356 Terminology Relating to Sampling and Analysis of
1.2 The concentration ranges are listed below. The range
Atmospheres
tested was confirmed using the interlaboratory collaborative
D2777 Practice for Determination of Precision and Bias of
test (see Table 1 for a statistical summary of the collaborative
Applicable Test Methods of Committee D19 on Water
test). D4453 Practice for Handling of High Purity Water Samples
D4691 Practice for Measuring Elements in Water by Flame
MDL Range of Method Range Tested
(mg/L) (2) (mg/L) (mg/L)
Atomic Absorption Spectrophotometry
D5012 Guide for Preparation of Materials Used for the
Calcium 0.009 0.03–3.00 0.168–2.939
Collection and Preservation of Atmospheric Wet Deposi-
Magnesium 0.003 0.01–1.00 0.039–0.682
Potassium 0.003 0.01–1.00 0.029–0.499
tion
Sodium 0.003 0.01–2.00 0.105–1.84
E131 Terminology Relating to Molecular Spectroscopy
1.3 The method detection limit (MDL) is based on single E275 Practice for Describing and Measuring Performance of
operator precision (2) and may be higher or lower for other Ultraviolet and Visible Spectrophotometers
operators and laboratories. Many workers have found that this E694 Specification for Laboratory Glass Volumetric Appa-
ratus
test method is reliable at lower levels than were tested, but the
IEEE/ASTM SI-10 Standard for Use of the International
precision and bias data presented are insufficient to justify their
System of Units (SI): The Modern Metric System
use at lower levels.
1.4 The values stated in SI units are to be regarded as
3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions:
standard.
3.1.1 For definitions of terms used in this test method, refer
1.5 This standard does not purport to address all of the
to Terminologies D883, D1129, D1356, E131, and Practices
safety concerns, if any, associated with its use. It is the
D4691, E275, and IEEE/ASTM SI-10.
responsibility of the user of this standard to establish appro-
3.1.2 method detection limit, MDL—the minimum concen-
priate safety and health practices and determine the applica-
tration of an analyte that can be reported with 99 % confidence
bility of regulatory limitations prior to use. Specific warning
that the value is above zero based on a standard deviation of
statements are given in 8.3, 8.7, 12.1.8, and Section 9.
greater than seven repetitive measurements of a solution
containing the analyte at a concentration near the low standard.
Theanalyteconcentrationofthissolutionshouldnotbegreater
than ten times the estimated MDL.
This test method is under the jurisdiction of ASTM Committee D22 on Air
Quality and is the direct responsibility of Subcommittee D22.03 on Ambient
Atmospheres and Source Emissions.
Current edition approved April 1, 2008. Published July 2008. Originally
published as D5086 – 90. Last previous edition D5086 – 01. DOI: 10.1520/D5086- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
01R08. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this test method. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5086 − 01 (2008)
TABLE 1 Interlaboratory Precision and Bias for Calcium, Magnesium, Potassium, and Sodium Determined from Analyte Spikes of
Synthetic Atmospheric Wet Deposition Samples
Amount Mean 95 % 95 %
A B
Number of S S Bias, Bias, Significant
t o
Element Added, Recovery, Reproducibility Repeatability
Observations mg/L % at 5 % Level
mg/L mg/L Limit Limit
Ca 18 0.168 0.160 0.0062 0.017 0.0063 0.018 −0.008 −4.76 yes
21 0.382 0.332 0.027 0.076 0.011 0.031 −0.030 −7.85 yes
19 0.769 0.722 0.018 0.050 0.0091 0.025 −0.047 −6.11 yes
21 1.448 1.334 0.038 0.106 0.025 0.070 −0.114 −7.87 yes
20 2.939 2.770 0.047 0.132 0.037 0.104 −0.169 −5.75 yes
Mg 18 0.039 0.037 0.0033 0.0092 0.0016 0.0045 −0.002 −5.13 yes
17 0.089 0.090 0.0061 0.017 0.0019 0.0053 0.001 1.12 no
15 0.178 0.180 0.0057 0.016 0.0029 0.0081 0.002 1.12 no
17 0.336 0.336 0.014 0.039 0.0038 0.011 0.00 0.00 no
17 0.682 0.696 0.012 0.034 0.0037 0.010 0.014 2.05 yes
K 16 0.029 0.043 0.0036 0.010 0.0032 0.0090 0.014 48.3 yes
16 0.065 0.068 0.0046 0.013 0.0012 0.0034 0.003 4.62 yes
15 0.130 0.132 0.013 0.036 0.0038 0.011 0.002 1.54 no
17 0.246 0.239 0.020 0.056 0.010 0.028 −0.007 −2.84 no
17 0.499 0.507 0.025 0.070 0.014 0.039 0.008 1.60 no
Na 18 0.225 0.219 0.014 0.039 0.0056 0.016 −0.006 −2.67 no
22 0.105 0.104 0.0010 0.027 0.0021 0.0059 −0.001 −0.95 no
20 0.239 0.235 0.0053 0.015 0.0038 0.011 −0.004 −1.67 yes
17 0.481 0.475 0.0070 0.020 0.0046 0.013 −0.006 −1.24 yes
18 0.906 0.856 0.0087 0.024 0.0073 0.020 −0.050 −5.52 yes
22 1.84 1.85 0.041 0.115 0.021 0.059 0.01 0.54 no
A
Between laboratory precision, reproducibility.
B
Within laboratory precision (pooled single operator precision), repeatability.
4. Summary of Test Method 5. Significance and Use
5.1 This test method may be used for the determination of
4.1 Asolutioncontainingthemetal(s)ofinterestisaspirated
calcium, magnesium, potassium, and sodium in atmospheric
as a fine mist into an air acetylene flame where it is converted
wet deposition samples.
to an atomic vapor consisting of ground state atoms. These
5.2 Emphasisisplacedontheeasilycontaminatedqualityof
ground state atoms are capable of absorbing electromagnetic
atmospheric wet deposition samples due to the low concentra-
radiation over a series of very narrow, sharply defined wave-
tion levels of dissolved metals commonly present.
lengths from a distinct line source of light, usually a hollow
cathode lamp specific to the metal of interest, passed through
5.3 Annex A1 represents cumulative frequency percentile
the flame. Light from the source beam, less whatever intensity
concentration plots of calcium, magnesium, potassium, and
was absorbed by the atoms of the metal of interest, is isolated
sodium obtained from analyses of over five thousand wet
bythemonochromatorandmeasuredbythephotodetector.The deposition samples. These data may be used as an aid in the
amount of light absorbed by the analyte is quantified by selectionofappropriatecalibrationstandardconcentrations. (3)
comparing the light transmitted through the flame to light
6. Interferences
transmitted by a reference beam.The amount of light absorbed
in the flame is proportional to the concentration of the metal in
6.1 A chemical interference can prevent, enhance, or sup-
solution. The relationship between absorption and concentra-
press the formation of ground state atoms in the flame. For
tion is expressed by Beer’s Law:
example,inthecaseofcalciumdeterminations,thepresenceof
phosphate or sulfate can result in the formation of a salt that
log I /I 5 abc 5 A (1)
~ !
o
hinders proper atomization of the solution when it is aspirated
where:
into the flame. This decreases the number of free, ground state
I = incident radiant power, atoms in the flame, resulting in lowered absorbance values.
o
I = transmitted radiant power,
Aluminum can cause a similar interference when measuring
a = absorptivity (constant for a given system),
magnesium. The addition of appropriate complexing agents,
b = sample path length,
suchaslanthanum,tothesamplesolutionreducesoreliminates
c = concentration of absorbing species, and
chemical interferences and may increase the sensitivity of this
A = absorbance.
test method.
The atomic absorption spectrophotometer is calibrated with
6.2 Alkali metals, such as potassium and sodium, can
standard solutions containing known concentrations of the
undergo ionization in an air-acetylene flame resulting in a
element(s) of interest. The concentration of each analyte in the
decrease in ground state atoms available for measurement by
unknown sample is determined from contructed calibration
atomic absorption. The addition of a large excess of an easily
curves. ionizable element, such as cesium, will eliminate this problem,
D5086 − 01 (2008)
since cesium will be preferentially ionized. The preferential 7.4 Laboratory Facilities—Laboratories used for the analy-
ionization of the cesium results in an enhanced atomic absorp- sis of atmospheric wet deposition samples should be free from
tion signal for both potassium and sodium. external sources of contamination.
7.4.1 The use of laminar flow clean air workstations is
6.3 If a sample containing low concentrations of the metal
recommended for sample processing and preparation to avoid
being measured is analyzed immediately after a sample having
the introduction of airborne contaminants. If a clean air
a concentration exceeding the concentration of the highest
workstations is unavailable, samples must be capped or cov-
calibration standard, sample carryover can result in elevated
ered prior to analysis.
readings due to residual metal from the previous sample. To
7.4.2 Apositive pressure environment within the laboratory
prevent this interference, routinely aspirate water for about 15
is recommended to minimize the introduction of external
s after a high concentration sample. Depending on the concen-
sourcesofcontaminantgasesandparticulates.Windowswithin
tration of metal in the last sample analyzed, it may be
the laboratory should be kept closed at all times and sealed if
necessarytorinseforlongertimeperiods.Completepurgingof
leaks are apparent.
the system is ascertained by aspirating water until the absor-
7.4.3 The use of disposable tacky floor mats at the entrance
bance readout returns to the baseline.
to the laboratory is helpful in reducing the particulate loading
6.4 Atmospheric wet deposition samples are characterized
within the room.
by low ionic strength and rarely contain enough salts to cause
interferences due to non-specific background absorbance. The
8. Reagents and Materials
use of background correction techniques is not necessary and
8.1 Purity of Reagents—Use reagent grade or higher grade
will decrease the signal to noise ratio and lessen precision.
chemicals for all solutions. All reagents shall conform to the
specifications of the Committee on Analytical Reagents of the
7. Apparatus
American Chemical Society (ACS) where such specifications
7.1 Atomic Absorption Spectrophotometer—Select a
are available.
double-beam instrument having a monochromator,
8.2 Purity of Water—Unless otherwise indicated, references
photodetector, pressure-reducing valves, adjustable spectral
to water shall be understood to mean reagent water as defined
bandwidth, and a wavelength range of 190 to 800 nm.
by Type I of Specification D1193. Point of use 0.2 µm filters
Peripheral equipment may include a strip chart recorder or a
arerecommendedforallfaucetssupplyingwatertopreventthe
suitable data system.
introduction of bacteria and/or ion exchange resins into re-
7.1.1 Burner—Use a long-path, single slot, air-acetylene
agents.
burner head supplied by the manufacturer of the spectropho-
8.3 Acetylene (Fuel)—Minimum acceptable acetylene pu-
tometer.
rity is 99.5 % (v/v). Change the cylinder when the pressure
7.1.2 Hollow Cathode Lamps—Single element lamps are
reaches 517 kPa (75 psig) if the acetylene is packed in acetone.
recommended. Multi-element lamps are available but are not
Pre-purified grades that contain a proprietary solvent can be
recommended. They have a shorter lifespan, are less sensitive,
used to 207 kPa (30 psig) before replacement.Avoid introduc-
require a higher operating current, and increase the chances of
ing these solvents into the instrument. Damage to the instru-
spectral interferences.
ment’s plumbing system can result. To prevent solvent
7.1.3 Monochromator—To increase the sensitivity for cal-
carryover, allow acetylene cylinders to stand for at least 24 h
cium and potassium measurements, a monochromator
before use. (Warning—Acetylene is a highly flammable gas.
equipped with a blaze grating in the range of 500 to 600 nm is
Follow the precautions in 9.3-9.6 regarding safe operating
recommended. For the analysis of magnesium and sodium, a
pressures, suitable plumbing, and operator safety.)
blaze grating in the range of 200 to 250 nm is adequate.
7.1.4 Photomultiplier Tube—A wide spectral range (160 to
8.4 Cesium Solution (Ionization Suppressant)—Dissolve
900 nm) photomultiplier tube is recommended. Select a red-
126.7gcesiumchloride(CsCl),driedat105°Cfor1h,inwater
sensitive photomultiplier tube to detect potassium at 766.5 nm
and dilute to 1 L. Store at room temperature in a high density
and to increase sensitivity for calcium at 422.7 nm.
polyethylene or polypropylene container.
7.2 Volumetric Pipets—MaintainasetofClassAvolumetric
8.5 Hydrochloric Acid (1+1)—Carefully add one volume of
pipets (see Specification E694) to be used only when making
concentrated hydrochloric acid (HCl, sp gr 1.19) to an equal
dilute calibration solutions for the analysis of atmospheric wet
volume of water.
deposition samples.Alternatively, disposable tip pipets may be
8.6 Hydrochloric Acid (1+19)—Carefully add 50 mL of
used.
concentrated hydrochloric acid (HCl, sp gr 1.19) to 900 mL of
7.3 VolumetricFlasks—MaintainasetofClassAvolumetric
water and dilute to 1 L.
flasks (see Specification E694) to be used only when making
dilute calibration solutions for the analysis of atmospheric wet
deposition samples.
Reagent Chemicals, American Chemical Society Specifications , American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
7.3.1 The first time any glassware is used for making stock
listed by the American Chemical Society, see Analar Standards for Laboratory
solutions and standards, clean with HCl (1+1) and rinse
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the Un
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