ASTM D3859-15(2023)

Standard Test Methods for Selenium in Water

SIGNIFICANCE AND USE
4.1 In most natural waters selenium concentrations seldom exceed 10 μg/L. However, the runoff from certain types of seleniferous soils at various times of the year can produce concentrations as high as several hundred micrograms per litre. Additionally, industrial contamination can be a significant source of selenium in rivers and streams.  
4.2 High concentrations of selenium in drinking water have been suspected of being toxic to animal life. Selenium is a priority pollutant and all public water agencies are required to monitor its concentration.  
4.3 These test methods determine the dominant species of selenium reportedly found in most natural and wastewaters, including selenities, selenates, and organo-selenium compounds.
SCOPE
1.1 These test methods cover the determination of dissolved and total recoverable selenium in most waters and wastewaters. Both test methods utilize atomic absorption procedures, as follows:    
Sections  
Test Method A—Gaseous Hydride AAS2, 3  
7 – 16  
Test Method B—Graphite Furnace AAS  
17 – 26  
1.2 These test methods are applicable to both inorganic and organic forms of dissolved selenium. They are applicable also to particulate forms of the element, provided that they are solubilized in the appropriate acid digestion step. However, certain selenium-containing heavy metallic sediments may not undergo digestion.  
1.3 These test methods are most applicable within the following ranges:    
Test Method A—Gaseous Hydride AAS2, 3  
1 μg/L to 20 μg/L  
Test Method B—Graphite Furnace AAS  
2 μg/L to 100 μg/L
These ranges may be extended (with a corresponding loss in precision) by decreasing the sample size or diluting the original sample, but concentrations much greater than the upper limits are more conveniently determined by flame atomic absorption spectrometry.  
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 11.12 and 13.14.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2023
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Replaces: ASTM D3859-15 - Standard Test Methods for Selenium in Water
• Effective Date: 01-Dec-2023
• Refers: ASTM D1129-13(2020)e1 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Referred By: ASTM D1971-16(2021)e1 - Standard Practices for Digestion of Water Samples for Determination of Metals by Flame Atomic Absorption, Graphite Furnace Atomic Absorption, Plasma Emission Spectroscopy, or Plasma Mass Spectrometry
• Effective Date: 01-Dec-2023
• Referred By: ASTM D4382-18 - Standard Test Method for Barium in Water, Atomic Absorption Spectrophotometry, Graphite Furnace
• Effective Date: 01-Dec-2023
• Referred By: ASTM D4691-17 - Standard Practice for Measuring Elements in Water by Flame Atomic Absorption Spectrophotometry
• Effective Date: 01-Dec-2023
• Referred By: ASTM D8006-16 - Standard Guide for Sampling and Analysis of Residential and Commercial Water Supply Wells in Areas of Exploration and Production (E&P) Operations
• Effective Date: 01-Dec-2023

Overview

ASTM D3859-15(2023): Standard Test Methods for Selenium in Water establishes comprehensive procedures for determining both dissolved and total recoverable selenium concentrations in various water samples. Developed by ASTM International, this standard is essential for ensuring accurate detection and monitoring of selenium-a chemical element that is both vital in trace amounts and potentially toxic at higher concentrations.

Selenium regularly appears in natural waters at less than 10 μg/L, but concentrations can spike to several hundred micrograms per liter due to industrial runoff, seleniferous soils, and other sources. Because high levels of selenium are a recognized environmental and public health concern, especially for animal and human life, regulatory agencies worldwide require robust, standardized monitoring methods like those defined in ASTM D3859-15.

Key Topics

• Test Method Scope: The standard covers both dissolved and total recoverable selenium in natural and wastewaters. It applies to inorganic and organic selenium compounds, and, when properly digested, to particulate forms.
• Analytical Techniques:
  • Test Method A: Gaseous Hydride Atomic Absorption Spectrometry (AAS), effective for selenium concentrations in the range of 1–20 μg/L.
  • Test Method B: Graphite Furnace Atomic Absorption Spectrometry, applicable for concentrations between 2–100 μg/L.
• Species Detected: Methods are validated for major selenium species in water, including selenite, selenate, and organo-selenium compounds.
• Precision and Sensitivity: The methods provide high precision across defined ranges, with guidance for extending analytical limits through dilution or sample size adjustments.
• Quality Assurance: The standard emphasizes strict quality control through calibration, precision checks, spiking, blank analysis, and use of reference materials.
• Safety and Compliance: Users must follow proper laboratory safety practices and comply with regulatory requirements, as selenium hydride (used in some test steps) is toxic.

Applications

• Environmental Monitoring: The test methods outlined are essential for environmental protection agencies and water quality laboratories monitoring selenium as a priority pollutant in rivers, streams, and lakes.
• Drinking Water Compliance: Public water suppliers rely on these methods to ensure selenium concentrations remain within regulatory safe limits, mitigating risks to human health.
• Industrial Wastewater Analysis: Facilities responsible for discharging wastewater must test for selenium to comply with environmental regulations and avoid contamination of water bodies.
• Ecological Risk Assessment: The methods support efforts to protect aquatic life by early detection of potentially toxic selenium concentrations in natural habitats.
• Research and Academic Use: Universities and research institutions use these standardized test procedures in water quality studies and analytical chemistry research.

Related Standards

ASTM D3859-15(2023) references and complements various other standards related to water analysis and trace element measurement, including:

• ASTM D1129 – Terminology Relating to Water
• ASTM D1193 – Specification for Reagent Water
• ASTM D3370 – Practices for Sampling Water from Flowing Process Streams
• ASTM D3919 – Practice for Measuring Trace Elements in Water by Graphite Furnace AAS
• ASTM D4841 – Practice for Estimation of Holding Time for Water Samples
• ASTM D5673 – Test Method for Elements in Water by ICP–Mass Spectrometry
• ASTM D5810 – Guide for Spiking into Aqueous Samples
• ASTM D5847 – Practice for Quality Control in Water Analysis

These related documents ensure consistent terminology, sampling, calibration, and validation across water analysis laboratories, providing greater reliability and comparability of selenium determination results.

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Keywords: ASTM D3859-15, selenium in water, selenium test method, water quality monitoring, atomic absorption spectrometry, environmental compliance, water analysis standards, dissolved selenium, total recoverable selenium.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3859 − 15 (Reapproved 2023)
Standard Test Methods for
Selenium in Water
This standard is issued under the fixed designation D3859; 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 1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 These test methods cover the determination of dissolved
ization established in the Decision on Principles for the
and total recoverable selenium in most waters and wastewaters.
Development of International Standards, Guides and Recom-
Both test methods utilize atomic absorption procedures, as
mendations issued by the World Trade Organization Technical
follows:
Barriers to Trade (TBT) Committee.
Sections
2, 3
Test Method A—Gaseous Hydride AAS 7 – 16
2. Referenced Documents
Test Method B—Graphite Furnace AAS 17 – 26
2.1 ASTM Standards:
1.2 These test methods are applicable to both inorganic and
D1129 Terminology Relating to Water
organic forms of dissolved selenium. They are applicable also
D1193 Specification for Reagent Water
to particulate forms of the element, provided that they are
D2777 Practice for Determination of Precision and Bias of
solubilized in the appropriate acid digestion step. However,
Applicable Test Methods of Committee D19 on Water
certain selenium-containing heavy metallic sediments may not
D3370 Practices for Sampling Water from Flowing Process
undergo digestion.
Streams
1.3 These test methods are most applicable within the
D3919 Practice for Measuring Trace Elements in Water by
following ranges:
Graphite Furnace Atomic Absorption Spectrophotometry
2, 3
Test Method A—Gaseous Hydride AAS 1 μg ⁄L to 20 μg ⁄L
D4841 Practice for Estimation of Holding Time for Water
Test Method B—Graphite Furnace AAS 2 μg ⁄L to 100 μg/L
Samples Containing Organic and Inorganic Constituents
These ranges may be extended (with a corresponding loss in
D5673 Test Method for Elements in Water by Inductively
precision) by decreasing the sample size or diluting the original
Coupled Plasma—Mass Spectrometry
sample, but concentrations much greater than the upper limits
D5810 Guide for Spiking into Aqueous Samples
are more conveniently determined by flame atomic absorption
D5847 Practice for Writing Quality Control Specifications
spectrometry.
for Standard Test Methods for Water Analysis
1.4 The values stated in SI units are to be regarded as
standard. The values given in parentheses are mathematical 3. Terminology
conversions to inch-pound units that are provided for informa-
3.1 Definitions:
tion only and are not considered standard.
3.1.1 For definitions of terms used in these test methods,
1.5 This standard does not purport to address all of the refer to Terminology D1129.
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro- 3.2.1 total recoverable selenium, n—a descriptive term
priate safety, health, and environmental practices and deter-
relating to the selenium forms recovered in the acid-digestion
mine the applicability of regulatory limitations prior to use.
procedure specified in these test methods.
For specific hazard statements, see 11.12 and 13.14.
4. Significance and Use
4.1 In most natural waters selenium concentrations seldom
These test methods are under the jurisdiction of ASTM Committee D19 on
exceed 10 μg/L. However, the runoff from certain types of
Water and are the direct responsibility of Subcommittee D19.05 on Inorganic
seleniferous soils at various times of the year can produce
Constituents in Water.
concentrations as high as several hundred micrograms per litre.
Current edition approved Dec. 1, 2023. Published January 2024. Originally
approved in 1984. Last previous edition approved in 2015 as D3859 – 15. DOI:
10.1520/D3859-15R23.
2 4
Lansford, M., McPherson, E. M., and Fishman, M. J., Atomic Absorption For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Newsletter, Vol 13, No. 4, 1974, pp. 103–105. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Pollack, E. N., and West, S. J., Atomic Absorption Newsletter, Vol 12, No. 1, Standards volume information, refer to the standard’s Document Summary page on
1973, pp. 6–8. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3859 − 15 (2023)
Additionally, industrial contamination can be a significant TEST METHOD A—GASEOUS HYDRIDE AAS
source of selenium in rivers and streams.
7. Scope
4.2 High concentrations of selenium in drinking water have
7.1 This test method covers the determination of dissolved
been suspected of being toxic to animal life. Selenium is a
and total recoverable selenium in the range from 1 μg ⁄L to
priority pollutant and all public water agencies are required to
20 μg ⁄L. The range may be extended by decreasing the sample
monitor its concentration.
size or diluting the original sample.
4.3 These test methods determine the dominant species of
7.2 This test method has been used successfully with
selenium reportedly found in most natural and wastewaters,
reagent water, natural water, wastewater, and brines. The
including selenities, selenates, and organo-selenium com-
information on precision may not apply to waters of other
pounds.
matrices.
5. Purity of Reagents
8. Summary of Test Method
5.1 Reagent grade chemicals shall be used in all tests.
8.1 The determination consists of the conversion of sele-
Unless otherwise indicated, it is intended that all reagents shall
nium in its various forms to gaseous selenium hydride (hydro-
conform to the specifications of the Committee on Analytical
gen selenide), with the subsequent analysis of the gas by flame
Reagents of the American Chemical Society, where such
AAS.
specifications are available. Other grades may be used, pro-
8.1.1 The conversion consists of (1) decomposition and
vided it is ascertained that the reagent is of sufficiently high
oxidation to selenium (VI), (2) reduction to selenium (IV), and
purity to permit its use without lessening the accuracy of the
(3) final reduction to selenium hydride.
determination.
8.1.2 The absorbance is determined at 196.0 nm in a
hydrogen-argon (air-entrained) flame.
5.2 Purity of Water—Unless otherwise indicated, reference
to water shall be understood to mean reagent water conforming
8.2 Sample concentrations are obtained directly from a
to Specification D1193, Type I. Other reagent water types may
simple concentration versus absorbance calibration curve.
be used provided it is first ascertained that the water is of
8.3 Total recoverable selenium is determined by treating the
sufficiently high purity to permit its use without adversely
entire sample as the procedure indicates, and the dissolved
affecting the bias and precision of the test method. Type II
selenium is determined by treating the filtrate after the sample
water was specified at the time of round robin testing of this
is filtered through a 0.45 μm membrane filter.
test method.
9. Interferences
6. Sampling
9.1 Mercury and arsenic at concentrations greater than
6.1 Collect the samples in accordance with Practices
500 μg ⁄L and greater than 100 μg/L, respectively, may inhibit
D3370. Take the samples in acid-washed TFE-fluorocarbon or
the formation of selenium hydride.
glass bottles. Other types of bottles may be used for sampling,
but should be checked for selenium absorption. The holding 10. Apparatus
time for the samples may be calculated in accordance with
10.1 An apparatus similar to that depicted in Fig. 1, with the
Practice D4841.
components specified in 10.2 – 10.4.8, is recommended for this
test method.
6.2 When determining only dissolved selenium, filter the
sample through a 0.45 μm membrane filter as soon as possible
10.2 Atomic Absorption Spectrophotometer—The instru-
after sampling. Add HNO to the filtrate to bring the pH to
3 ments shall consist of an atomizer and burner, suitable pressure
<2.0.
and flow regulation devices capable of maintaining constant
diluent and fuel pressure for the duration of the test, a selenium
6.3 When determining total recoverable selenium, add
lamp, an optical system capable of isolating the desired
HNO to the unfiltered sample to a pH of <2.0 within 15 min
wavelength, an adjustable slit, a photomultiplier tube or other
of collecting the sample.
photosensitive devices such as a light measuring and amplify-
NOTE 1—Alternatively, the pH may be adjusted in the laboratory if the
ing device, and a readout mechanism for indicating the amount
sample is returned within 14 days. However, acid must be added at least
of absorbed radiation. A background corrector may be used, but
24 h before analysis to dissolve any metals that adsorb to the container
is not absolutely essential.
walls. This could reduce hazards of working with acids in the field when
10.2.1 Selenium Electrodeless Discharge Lamp—The sensi-
appropriate.
tivity of selenium to atomic absorption spectroscopy is gener-
ally improved with this lamp, although some hollow-cathode
lamps produce equivalent results. The intensity and stability of
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by the American Chemical
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, A static system, such as one using a balloon, has been found satisfactory for this
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma- purpose. See McFarren, E. F., “New, Simplified Method for Metal Analysis,”
copeial Convention, Inc. (USPC), Rockville, MD. Journal of American Water Works Association, Vol 64, 1972, p. 28.
D3859 − 15 (2023)
FIG. 1 Apparatus for Selenium Determination
the lamp shall be adequate to determine selenium in the range 10.4 Additional Equipment:
from 1 μg ⁄L to 20 μg ⁄L.
10.4.1 Flask Header—The flask header shall consist of a
10.2.2 Recorder or Digital Readout, or Both—Any
three-hole rubber stopper into which is inserted:
multirange, variable-speed recorder, or digital readout acces-
10.4.1.1 A sintered-glass aeration tube for the argon sweep
sory that is compatible with the atomic absorption detection
gas,
system, is suitable.
10.4.1.2 A small gas chromatographic-type septum (5 mm
10.2.3 The manufacturer’s instructions are to be followed
to 10 mm in diameter), for injection of the borohydride
for all instrument parameters.
solution, and
10.3 Gas System: 10.4.1.3 A glass outlet tube for the reaction gases to exit.
10.3.1 See 11.14 for materials for the gas system.
NOTE 2—Instead of the gas chromatographic-type septum, a more
10.3.2 Pressure-Reducing Valves—Pressure-reducing valves
secure seal may be obtained by using a glass tube with a septum cap.
shall be capable of maintaining argon pressure at 275 kPa
These items are commercially available on an individual basis. A different
(40 psi) and hydrogen pressure at 138 kPa (20 psi). header may be used if proven reliable.
D3859 − 15 (2023)
10.4.2 Fittings and Adapters—Stainless steel fittings and 11.10 Selenium Solution, Intermediate (1.00 mL = 10 μg
adapters shall be used to install the reaction-flask header in selenium)—Dilute 5 mL of the selenium stock solution to
series with the auxiliary oxidant line and the burner. Plastic or 500 mL with HCl (1 + 99).
other metals may be substituted if proven acceptable.
11.11 Selenium Solution, Standard (1.00 mL = 0.10 μg
10.4.3 Tubing—Any commercially available plastic tubing
selenium)—Dilute 10 mL of the selenium intermediate solution
that is not susceptible to attack by hydrochloric acid, selenium
to 1000 mL with HCl (1 + 99). Prepare fresh daily and store in
hydride, or other gases from the reaction mixture is acceptable.
a TFE-fluorocarbon or other acceptable container. To minimize
Poly(vinyl chloride) tubing has been found acceptable.
waste only prepare 100 mL of the Selenium Standard Solution.
10.4.4 Gas-Flow Regulator—A suitable in-line gas-flow
11.12 Sodium Borohydride Solution (4 g/100 mL)—
valve shall be used to adjust the flow of argon to the
Dissolve 4 g of sodium borohydride (NaBH ) and 2 g of
reaction-flask header.
sodium hydroxide in water and dilute to 100 mL. Prepare fresh
10.4.5 Water Trap (optional)—Any commercially available
weekly. (Warning—Sodium borohydride reacts strongly with
glass trap suitable to prevent carryover moisture from going to
acids.)
the burner is acceptable.
11.13 Sodium Hydroxide Solution (4 g/L)—Dissolve 4 g of
10.4.6 One-Way Gas Check Valve (optional)—A one-way
sodium hydroxide (NaOH) in water and dilute to 1 L.
check valve can be installed in series with the water trap and
burner to prevent hydrogen from back flowing to the generat-
11.14 Gases:
ing flask whenever samples are changed. However, precaution-
11.14.1 Argon (nitrogen may be used in place of argon)—
ary measures could generally preclude the use of this device,
Standard, commercially available argon is the usual diluent.
since only when the flask header is removed for prolonged
11.14.2 Hydrogen—Standard, commercially available hy-
periods would there be significant hydrogen back flow.
drogen is the usual fuel.
10.4.7 Reaction Flasks, 250 mL spoutless beakers, or their
equivalent, with graduations may be used. Conical and re- 12. Standardization
stricted neck flasks do not perform as reliably as spoutless
12.1 Transfer 0.0 mL, 0.5 mL, 1.0 mL, 2.0 mL, 5.0 mL, and
beakers.
10.0 mL portions of the standard selenium solution
10.4.8 Hypodermic Syringe, 2 mL capacity with a 50 mm
(1.0 mL = 0.10 μg Se) (11.11) to freshly washed 250 mL
needle.
reaction flasks. Adjust the volume to 50 mL with water.
Analyze at least six working standards containing concentra-
11. Reagents and Materials
tions of selenium that bracket the expected sample
concentration, prior to analysis of samples, to calibrate the
11.1 Calcium Chloride Solution (30 g/L)—Commercially
instrument.
purchase or dissolve 30 g of calcium chloride (CaCl ·2H O) in
2 2
water and dilute to 1 L.
12.2 Proceed as directed in 13.3 – 13.15.
11.2 Hydrochloric Acid (sp gr 1.19), concentrated hydro-
12.3 Calibrate the spectrophotometer to output micrograms
chloric acid (HCl).
of selenium directly, if provided with this capability or prepare
a calibration curve by plotting absorbance (or recorder scale
11.3 Hydrochloric Acid (1 + 1)—Add 1 volume of HCl (sp
readings) versus micrograms of selenium on linear graph
gr 1.19) to 1 volume of water. Always add acid to water.
paper.
11.4 Hydrochloric Acid (1 + 99)—Add 1 volume of HCl (sp
gr 1.19) to 99 volumes of water. Always add acid to water.
13. Procedure
11.5 Methyl Orange Indicator Solution (25 mg/100 mL)—
13.1 It is emphasized that careful control of pH, oxidant
Dissolve 25 mg of methyl orange in 100 mL of water.
concentration, temperature, and time are imperative if accurate
and precise selenium determinations are to be obtained.
11.6 Nitric Acid (sp gr 1.42), concentrated nitric acid
(HNO ).
3 13.2 For each sample, transfer 50 mL or less (to contain not
more than 1.0 μg selenium) to a freshly washed 250 mL
11.7 Nitric Acid (1 + 99)—Add 1 volume of HNO (sp gr
reaction flask. Make up to 50 mL with water if necessary.
1.42) to 99 volumes of water.
13.3 To each sample, standard, and blank, add a few drops
11.8 Potassium Permanganate Solution (0.3 g/L)—Dissolve
of methyl orange solution (11.5), 0.5 mL of CaCl solution
0.3 g of potassium permanganate (KMnO ) in water and dilute
(11.1) and three or four boiling stones.
to 1 L.
13.4 Adjust the pH to the red end point of methyl orange
11.9 Selenium Solution, Stock (1.00 mL = 1.00 mg
(pH = 3.1) with HCl (1 + 99) (11.4) or NaOH solution (4 g/L)
selenium)—Accurately weigh 1.000 g of gray elemental sele-
(11.13). Add 0.5 mL of HCl (1 + 99) in excess. A pH meter
nium and place in a small beaker. Add 5 mL of HNO (sp gr
may be used in place of the indicator if the sample is
1.42). Warm until the reaction is complete, then cautiously
sufficiently discolored to affect the methyl orange end point.
evaporate to dryness. Redissolve with HCl (1 + 99) and dilute
to 1 L with the same acid solution. 13.5 Add potassium permanganate solution (11.8) dropwise
11.9.1 A purchased metal selenium stock solution of appro- (about 3 drops) to maintain the purple tint indicating excess
priate known purity is also acceptable. KMnO . Boil the solution on a hotplate, carefully maintaining
D3859 − 15 (2023)
the purple tint until the volume is reduced to about 25 mL. Add flask, with negligible solution carryover into the outlet line.
2 mL of NaOH solution (4 g/L) (11.13) and concentrate the The set-up is then complete.
solutions to dryness, being careful not to overheat the residue.
13.12 If a recorder is used, adjust the span so that an
13.6 Cool and add 15 mL of concentrated HCl (sp gr 1.19) absorbance of 0.500 from the spectrophotometer reads full
scale on the recorder.
(11.2). Heat on a hot water or steam bath for 20 min. Do not
boil. This step reduces the selenium (VI) to selenium (IV).
13.13 Rinse the reaction flask and header with water and
introduce the blank, sample, or standard into the reaction flask.
NOTE 3—Many laboratories have found block digestion systems a
useful way to digest samples for trace metals analysis. Systems typically Replace the header and secure to form a tight seal. Allow the
consist of either a metal or graphite block with wells to hold digestion
system to stabilize and prepare to record the peak absorbance
tubes. The block temperature controller must be able to maintain unifor-
or the total absorbance.
mity of temperature across all positions of the block. For trace metals
analysis, the digestion tubes should be constructed of polypropylene and 13.14 The precision of this test method is highly dependent
have a volume accuracy of at least 0.5 %. All lots of tubes should come
on the use of a consistently reproduced technique in this final
with a certificate of analysis to demonstrate suitability for their intended
step. Inject the 2 mL hypodermic needle through the septum
purpose.
and quickly add 2.0 mL NaBH solution (4 g/100 mL) (11.12)
13.7 Cool and add HCl (1 + 1) (11.3) to adjust the volume to
to the sample. The H Se evolution will peak within a few
50 mL. Hold these solutions until all samples and standards are
seconds, but will trail off for up to 30 s afterward. After the
brought to this stage.
H Se is swept from the system, remove the header and rinse
well with water. (Warning—Selenium hydride is toxic to
13.8 Set the atomic absorption instrument parameters in
certain organs of the body. Avoid inhalation.)
accordance with the manufacturer’s instructions. Typical set-
tings are as follows:
13.15 Treat each succeeding sample, blank, and standard in
Grating ultraviolet
a like manner.
Wavelength 196.0 nm
Burner triple-slot or equivalent
14. Calculation
Radiation Source selenium electrodeless discharge lamp or equivalent
Slit 2.0 nm
14.1 Determine the weight of selenium in each sample by
Flame hydrogen-argon (nitrogen may be used in place of
referring to 12.3. Calculate the concentration of selenium in the
argon)
sample in micrograms per litre, using Eq 1:
13.9 If the gas control box is not equipped with separate
Selenium µg/L 5 ~1000/V! × W (1)
controls for argon and hydrogen, simply connect the oxidant
inlet line for the control box to the argon tank regulator and
where:
connect the fuel inlet line for the control box to the hydrogen
1000 = 1000 mL / Litre,
tank regulator. The oxidant controls will then control the argon
V = volume of sample, mL, and
diluent gas and the fuel controls will control the hydrogen gas.
W = weight of selenium in sample, μg.
To preclude the possibility of accidentally mixing the hydrogen
fuel with the air oxidant normally used with atomic absorption
15. Precision and Bias
spectroscopy, shut off all sources of air oxidant to the system.
15.1 The overall and single-operator precision of this test
Set the tank pressures, the burner control box pressures, and the
method within its designated range for reagent water and
flow rates in accordance with the manufacturer’s instructions
nonreagent water varies with the quantity being measured in
for argon and hydrogen.
accordance with Table 1. These values were established for
13.10 Center the burner about 5 mm below the optical light
four laboratories, using six operators over three consecutive
path. Ignite the flame. Since the flame does not give off visible
days. The nonreagent waters included natural, waste, and brine
light, optical flame sensors must be bypassed, but the presence
waters.
of the low-temperature flame may be verified by aspirating tap
water, which contains soluble salts that impart color to the
flame. Optimize the burner position to give maximum absor-
Supporting data have been filed at ASTM International Headquarters and may
be obtained by requesting Research Report RR:D19-1056. Contact ASTM Customer
bance while aspirating the intermediate selenium standard
Service at [e-mail].
(1.0 mL = 10 μg selenium).
13.11 Interrupt the auxiliary oxidant line at the burner
TABLE 1 Overall (S ) and Single-Operator (S ) Interlaboratory
T O
connection and attach the gas lines, the flask header, and the
Precision for Selenium by Gaseous Hydride AAS, Test Method A
associated equipment. Connect in series, in this order, the
Concentration (X),
S S
T O
auxiliary oxidant line, the in-line gas flow regulator, and the μg/L
header aeration tube. Then connect the header outlet tube, the Reagent Water
2.79 0.95 0.72
water trap (optional), the one-way check valve (optional), and
8.50 1.62 1.44
the auxiliary oxidant inlet. Use minimum lengths of tubing to
17.89 2.98 1.71
minimize dilution of the selenium hydride. Attach a reaction Natural Water
2.69 0.69 0.78
flask containing 50 mL of water to the flask header. With argon
8.56 1.70 1.63
flowing through the system, adjust the in-line flow regulator to
18.35 2.13 1.67
permit a maximum flow of the argon sweep gas to the reaction
D3859 − 15 (2023)
15.1.1 The overall precision for reagent water varies lin- 16.2.4 It is recommended to analyze a continuing calibra-
early with the quantity being measured, and it may be tion blank (CCB) and continuing calibration verification
expressed mathematically using Eq 2: (CCV) at a 10 % frequency. The results should fall within the
expected precision of the method or 615 % of the known
S 5 0.146X10.49 (2)
t
concentration.
where:
16.3 Initial Demonstration of Laboratory Capability:
S = overall precision, μg/L, and
t
16.3.1 If a laboratory has not performed the test before, or if
X = concentration of selenium, μg/L.
there has been a major change in the measurement system, for
15.2 The bias of this test method determined from recover-
example, new analyst, new instrument, and so forth, a precision
ies of known amounts of selenium from selenium dioxide and
and bias study must be performed to demonstrate laboratory
selenium triphenylchloride in a series of prepared standards are
capability.
given in Table 2.
16.3.2 Analyze seven replicates of a standard solution
prepared from an Independent Reference Material containing a
15.3 The information on precision and bias may not apply to
midrange concentration of selenium. The matrix and chemistry
other wastewaters.
of the solution should be equivalent to the solution used in the
15.4 This section on precision and bias conforms to Practice
collaborative study. Each replicate must be taken through the
D2777 – 77 which was in place at the time of collaborative
complete analytical test method including any sample preser-
testing. Under the allowances made in 1.4 of Practice
vation and pretreatment steps.
D2777 – 13, these precision and bias data do meet existing
16.3.3 Calculate the mean and standard deviation of the
requirements of interlaboratory studies of Committee D19 test
seven values and compare to the acceptable ranges of bias in
methods.
Table 2. This study should be repeated until the recoveries are
within the limits given in Table 1. If a concentration other than
16. Quality Control
the recommended concentration is used, refer to Practice
16.1 In order to be certain that analytical values obtained
D5847 for information on applying the F test and t test in
using these test methods are valid and accurate within the
evaluating the acceptability of the mean and standard devia-
confidence limits of the test, the following QC procedures must
tion.
be followed when analyzing selenium.
16.4 Laboratory Control Sample (LCS):
16.2 Calibration and Calibration Verification:
16.4.1 To ensure that the test method is in control, prepare
16.2.1 Analyze at least six working standards containing
and analyze a LCS containing a known concentration of
concentrations of selenium that bracket the expected sample
selenium with each batch (laboratory-defined or twenty
concentration, prior to analysis of samples, to calibrate the
samples). The laboratory control samples for a large batch
instrument (see 12.1). The calibration correlation coefficient
should cover the analytical range when possible. It is
shall be equal to or greater than 0.990.
recommended, but not required to use a second source, if
16.2.2 Verify instrument calibration after standardization by
possible and practical for the LCS. The LCS must be taken
analyzing a standard at the concentration of one of the
through all of the steps of the analytical method including
calibration standards. The concentration of a mid-range stan-
sample preservation and pretreatment. The result obtained for
dard should fall within 615 % of the known concentration.
a mid-range LCS shall fall within 615 % of the known
Analyze a calibration blank to verify system cleanliness.
concentration.
16.2.3 If calibration cannot be verified, recalibrate the
16.4.2 If the result is not within these limits, analysis of
instrument.
samples is halted until the problem is corrected, and either all
the samples in the batch must be reanalyzed, or the results must
be qualified with an indication that they do not fall within the
performance criteria of the test method.
TABLE 2 Recovery and Bias Data, Test Method A
16.5 Method Blank:
(Gaseous Hydride AAS)
16.5.1 Analyze a reagent water test blank with each
Statistically
Amount Amount
Recovery, Significant at laboratory-defined batch. The concentration of selenium found
Added, Found, Bias, %
% 95 %
in the blank should be less than 0.5 times the lowest calibration
μg/L μg/L
Confidence Level
standard. If the concentration of selenium is found above this
level, analysis of samples is halted until the contamination is
Reagent Water (Type II)
eliminated, and a blank shows no contamination at or above
3 2.8 93 −7 no
this level, or the results must be qualified with an indication
8 8.5 106 + 6 no
that they do not fall within the performance criteria of the test
17 17.9 105 + 5 no
method.
Nonreagent Water (Natural, Waste, and Brine)
16.6 Matrix Spike (MS):
3 2.7 90 −10 no
16.6.1 To c
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