ASTM D3869-15(2023)

Standard Test Methods for Iodide and Bromide Ions in Brackish Water, Seawater, and Brines

SIGNIFICANCE AND USE
4.1 Identification of a brackish water, seawater, or brine is determined by comparison of the concentrations of their dissolved constituents. The results are used to evaluate the origin of the water, determine if it is a possible pollutant or determine if it is a commercial source of a valuable constituent such as iodine or bromine.
SCOPE
1.1 These test methods2 cover the determination of soluble iodide and bromide ions, or both, in brackish water, seawater, and brines. Four test methods are given as follows:  
1.1.1 Test Method A for both Iodide and Bromide Ions—Volumetric, for concentrations from 0.2 mg/L to 2000 mg/L iodide and from 5 mg/L to 6500 mg/L bromide (Sections 7 – 15).  
1.1.2 Test Method B for Iodide Ion—Colorimetric, for concentrations from 0.2 mg/L to 2000 mg/L iodide (Sections 16 – 25).  
1.1.3 Test Method C for Iodide Ion—Selective electrode, for concentrations from 1 mg/L to 2000 mg/L iodide (Sections 26 – 34).  
1.1.4 Test Method D for Bromide Ion—Colorimetric, for concentrations from 40 mg/L to 6500 mg/L bromide (Sections 35 – 44).  
1.2 Test Method A is intended for use on all brackish waters, seawaters, and brines that contain appreciable amounts of iodide or bromide ions or both. Test Methods B, C, and D, because of their rapidity and sensitivity, are recommended for the analysis of brackish waters, seawaters, and brines in the field and in the laboratory.  
1.3 Samples containing from 0.2 mg/L to 2000 mg/L of iodide or 5 mg/L to 6500 mg/L of bromide may be analyzed by these methods.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 precautionary statements, see 20.2 and 39.2.  
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: 31-Mar-2023
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D2777-12 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jun-2012
• Refers: ASTM D5810-96(2011) - Standard Guide for Spiking into Aqueous Samples
• Effective Date: 01-May-2011
• Refers: ASTM D3370-10 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2010
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM E275-08 - Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
• Effective Date: 15-Oct-2008
• Refers: ASTM D3370-08 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Oct-2008
• Refers: ASTM D2777-08 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jan-2008
• Refers: ASTM D3370-07 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2007
• Refers: ASTM D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D2777-06 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Aug-2006
• Refers: ASTM D5810-96(2006) - Standard Guide for Spiking into Aqueous Samples
• Effective Date: 15-Aug-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1129-06 - Standard Terminology Relating to Water
• Effective Date: 15-Feb-2006

Overview

ASTM D3869-15(2023) establishes standardized test methods for determining soluble iodide and bromide ions in brackish water, seawater, and brines. Developed by ASTM International, this standard is crucial for laboratories, researchers, and industries engaged in water quality analysis, environmental monitoring, and resource evaluation. By providing methods for measuring iodide and bromide concentrations, the standard supports assessments related to water origin, potential contamination, and the identification of water as a commercial source for iodine and bromine.

Key Topics

• Scope of Testing

  • Methods cover the analysis of iodide (I⁻) and bromide (Br⁻) in various saline water samples.
  • Applicable concentration ranges:
    • Iodide: 0.2 mg/L to 2000 mg/L
    • Bromide: 5 mg/L to 6500 mg/L

• Test Methods Included

  • Method A: Volumetric – For both iodide and bromide ions
  • Method B: Colorimetric – For iodide ion
  • Method C: Selective Electrode – For iodide ion
  • Method D: Colorimetric – For bromide ion

• Analytical Context

  • Designed for both laboratory and field use.
  • Rapid and sensitive methods (B, C, D) are optimal for quick assessments.

• Measurement Units

  • All results are reported in SI units (mg/L), ensuring consistency and global applicability.

• Quality and Safety

  • Emphasizes the need for reagent purity and proper calibration.
  • Users are responsible for safety and regulatory compliance during testing.

Applications

• Water Resource Evaluation

  • Identify sources of brackish water, seawater, and brine based on dissolved ion composition.
  • Determine suitability of water as a source for commercial iodine or bromine extraction.

• Environmental Monitoring

  • Assess pollution levels and trace potential contamination sources in natural waters and industrial discharges.
  • Monitor brackish or marine environments for compliance with environmental regulations.

• Industrial Quality Control

  • Support operations where iodide and bromide concentrations must be tightly controlled, e.g., in chemical production or oilfield water management.

• Scientific Research

  • Provide reliable methods for studying geochemical processes, water-rock interactions, and marine chemistry.

• Field and Laboratory Testing

  • Rapid test methods facilitate immediate decisions in remote locations and routine laboratory workflows.

Related Standards

• ASTM D1129 – Terminology Relating to Water
• ASTM D1193 – Specification for Reagent Water
• ASTM D2777 – Practice for Determination of Precision and Bias of Water Test Methods
• ASTM D3370 – Practices for Sampling Water from Flowing Process Streams
• ASTM D5810 – Guide for Spiking into Aqueous Samples
• ASTM D5847 – Practice for Writing Quality Control Specifications for Water Analysis
• ASTM E60 – Practice for Analysis of Metals, Ores, and Related Materials by Spectrophotometry
• ASTM E200 – Practice for Preparation and Standardization of Chemical Solutions
• ASTM E275 – Practice for Measuring Performance of Ultraviolet and Visible Spectrophotometers

Practical Value

Adherence to ASTM D3869-15(2023) ensures consistent, reliable determination of iodide and bromide ions in water samples across a wide range of industries and research applications. Implementing these standardized test methods:

• Improves data comparability in environmental studies
• Enables informed decision-making for resource management and pollution control
• Meets international best practices and regulatory requirements for water analysis

These methods are widely recognized for supporting strategic water resource, environmental, and chemical industry needs globally.

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: D3869 − 15 (Reapproved 2023)
Standard Test Methods for
Iodide and Bromide Ions in Brackish Water, Seawater, and
Brines
This standard is issued under the fixed designation D3869; 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 1.5 This standard does not purport to address all of the
2 safety concerns, if any, associated with its use. It is the
1.1 These test methods cover the determination of soluble
responsibility of the user of this standard to establish appro-
iodide and bromide ions, or both, in brackish water, seawater,
priate safety, health, and environmental practices and deter-
and brines. Four test methods are given as follows:
mine the applicability of regulatory limitations prior to use.
1.1.1 Test Method A for both Iodide and Bromide Ions—
For specific precautionary statements, see 20.2 and 39.2.
Volumetric, for concentrations from 0.2 mg ⁄L to 2000 mg/L
1.6 This international standard was developed in accor-
iodide and from 5 mg ⁄L to 6500 mg/L bromide (Sections 7 –
dance with internationally recognized principles on standard-
15).
ization established in the Decision on Principles for the
1.1.2 Test Method B for Iodide Ion—Colorimetric, for con-
Development of International Standards, Guides and Recom-
centrations from 0.2 mg ⁄L to 2000 mg ⁄L iodide (Sections 16 –
mendations issued by the World Trade Organization Technical
25).
Barriers to Trade (TBT) Committee.
1.1.3 Test Method C for Iodide Ion—Selective electrode, for
concentrations from 1 mg ⁄L to 2000 mg/L iodide (Sections 26
2. Referenced Documents
– 34).
2.1 ASTM Standards:
1.1.4 Test Method D for Bromide Ion—Colorimetric, for
D1129 Terminology Relating to Water
concentrations from 40 mg ⁄L to 6500 mg/L bromide (Sections
D1193 Specification for Reagent Water
35 – 44).
D2777 Practice for Determination of Precision and Bias of
1.2 Test Method A is intended for use on all brackish waters,
Applicable Test Methods of Committee D19 on Water
seawaters, and brines that contain appreciable amounts of
D3370 Practices for Sampling Water from Flowing Process
iodide or bromide ions or both. Test Methods B, C, and D,
Streams
because of their rapidity and sensitivity, are recommended for
D5810 Guide for Spiking into Aqueous Samples
the analysis of brackish waters, seawaters, and brines in the
D5847 Practice for Writing Quality Control Specifications
field and in the laboratory.
for Standard Test Methods for Water Analysis
1.3 Samples containing from 0.2 mg ⁄L to 2000 mg ⁄L of E60 Practice for Analysis of Metals, Ores, and Related
iodide or 5 mg ⁄L to 6500 mg ⁄L of bromide may be analyzed by
Materials by Spectrophotometry
these methods. E200 Practice for Preparation, Standardization, and Storage
of Standard and Reagent Solutions for Chemical Analysis
1.4 The values stated in SI units are to be regarded as
E275 Practice for Describing and Measuring Performance of
standard. No other units of measurement are included in this
Ultraviolet and Visible Spectrophotometers
standard.
3. Terminology
3.1 Definitions—For definitions of terms used in these test
These test methods are under the jurisdiction of ASTM Committee D19 on
methods, refer to Terminology D1129.
Water and are the direct responsibility of Subcommittee D19.05 on Inorganic
Constituents in Water.
Current edition approved April 1, 2023. Published April 2023. Originally 4. Significance and Use
approved in 1979. Last previous edition approved in 2015 as D3869 – 15. DOI:
4.1 Identification of a brackish water, seawater, or brine is
10.1520/D3869-15R23.
Additional information is contained in the following references: Collins, A. G., determined by comparison of the concentrations of their
Geochemistry of Oilfield Waters, Elsevier, New York, N.Y., 1975, 496 pp.American
Petroleum Institute, API Recommended Practice for Analysis of Oilfield Waters,
Subcommittee on Analysis of Oilfield Waters, API RP, 45 2nd ed, 1968, 49 pp.Hoke, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
S. H, Fletcher, G. E., and Collins, A. G., “Fluoride and Iodide Selective Electrodes contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Applied to Oilfield Brine Analysis,” US Department of Energy, Report of Standards volume information, refer to the standard’s Document Summary page on
Investigations, BETC/RI-78/7, 1978. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3869 − 15 (2023)
dissolved constituents. The results are used to evaluate the 9. Interferences
origin of the water, determine if it is a possible pollutant or
9.1 Iron, manganese, and organic matter can interfere (Note
determine if it is a commercial source of a valuable constituent
1). They are removed by precipitation and filtration. Remaining
such as iodine or bromine.
traces of iron are masked with fluoride.
NOTE 1—Brines containing surfactants can cause emulsion problems, in
5. Reagents
which case a suitable emulsion breaker can be used.
5.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
10. Apparatus
all reagents shall conform to the specification of the Committee
10.1 Mechanical Bottle Shaker.
on Analytical Reagents of the American Chemical Society,
10.2 Bottles, 200-mL, for use on mechanical shaker.
where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
10.3 Pipets.
sufficiently high purity to permit its use without lessening the
10.4 Hot-Water Bath, thermostatically controlled to 61 °C.
accuracy of the determination.
10.5 Erlenmeyer Flasks, 250-mL.
5.2 Purity of Water—Unless otherwise indicated, reference
to water shall be understood to mean reagent water conforming
11. Reagents and Materials
to Specification D1193, Type I. Other reagent water types may
be used provided it is first ascertained that the water is of
11.1 Acetic Acid, glacial.
sufficiently high purity to permit its use without adversely
11.2 Ammonium Molybdate Solution—Dissolve 2 g of am-
affecting the precision and bias of the test method. Type III
monium molybdate in water and dilute to 100 mL.
water was specified at the time of round robin testing of this
11.3 Bromine Water (Saturated)—Add to 250 mL of water
test method.
slightly more liquid bromine (8 mL to 10 mL) than will
dissolve on shaking. Store in a glass-stoppered amber bottle.
6. Sampling
11.4 Calcium Carbonate (CaCO ), powdered.
6.1 Collect the sample in accordance with Practices D3370.
11.5 Calcium Oxide (CaO), anhydrous powdered.
TEST METHOD A—VOLUMETRIC FOR IODIDE
AND BROMIDE 11.6 Hydrochloric Acid (1 + 1)—Add 1 volume of HCl (sp
gr 1.19) to 1 volume of water.
7. Scope
11.7 Hydrochloric Acid (1 + 3)—Add 1 volume of HCl (sp
7.1 This test method is applicable to brackish waters, gr 1.19) to 3 volumes of water.
seawaters, and brines, and is recommended for such waters
11.8 Hydrochloric Acid (1 + 199)—Add 1 volume of HCl
containing appreciable amounts of iodide or bromide, or both.
(sp gr 1.19) to 199 volumes of water.
The test method can be used for concentrations as high as 2000
11.9 Methyl Red Indicator Solution (0.1 g/L)—Dissolve
mg/L iodide and 6500 mg/L bromide.
0.01 g of water-soluble methyl red in water and dilute to 100
mL.
8. Summary of Test Method
11.10 Potassium Fluoride (KF·2H O), crystalline.
8.1 Iodide in the sample is oxidized with bromine to iodate
in a buffered solution, the excess bromine is decomposed with
11.11 Potassium Iodide (KI), crystals, free of iodates when
sodium formate, and the iodate reacts with added iodide to
tested in accordance with American Chemical Society (ACS)
form iodine which is titrated with sodium thiosulfate.
specifications.
8.2 Iodide and bromide are oxidized to iodate and bromate,
11.12 Sodium Acetate Solution (275 g/L)—Dissolve 275 g
respectively, with hypochlorite. The excess hypochlorite is
of sodium acetate trihydrate (NaC H O ·3H O) in water, to
2 3 2 2
destroyed with sodium formate, leaving iodate and bromate to
dilute to 1 L, and filter.
react with added iodide to liberate iodine which is titrated with
11.13 Sodium Chloride (NaCl), crystals, which, in addition
sodium thiosulfate.
to satisfying ACS specifications, must be free of iodide, iodate,
8.3 The bromide concentration is calculated by difference
bromide, and bromate.
between the iodide and combined iodide and bromide deter-
11.14 Sodium Formate Solution (500 g/L)—Dissolve 50 g
minations.
of sodium formate (NaCHO ) in hot water and dilute to 100
mL. This solution must be freshly prepared.
11.15 Sodium Hypochlorite Solution—Use a fresh commer-
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
cial sodium hypochlorite or bleach solution containing ap-
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by the American Chemical proximately 5 % NaClO.
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
11.16 Sodium Thiosulfate Solution (0.1 N)—Prepare and
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
copeial Convention, Inc. (USPC), Rockville, MD. standardize as directed in Practice E200.
D3869 − 15 (2023)
11.17 Sodium Thiosulfate Solution (0.01 N)—With a cali- 12.10 Adjust the pH of the solution with HCl (1 + 3) (11.7)
brated pipet transfer 25 mL of the 0.1 N Na S O solution to a pH between 5.5 and 6.0. Heat at 90 °C for 10 min. (A small
2 2 3
(11.16) into a 250-mL volumetric flask. Dilute to the mark with amount of undissolved CaCO should remain at this point.)
water that has been freshly boiled and cooled then mix well.
12.11 Remove the flask and cautiously add 10 mL of
This solution shall be prepared not more than 2 days before it
sodium formate solution (11.14), return the flask to the water
is to be used.
bath, and keep the contents hot for 5 min more. Observe the
11.18 Starch Indicator Solution—Make a paste of 6 g of timing closely. Rinse down the inside of the flask with a few
arrowroot or soluble iodometric starch with cold water. Pour millilitres of water and allow the solution to cool to room
the paste into 1 L of boiling water. Add 20 g of KOH, mix temperature. Do not use a water bath.
thoroughly, and allow to stand for 2 h. Add 6 mL of glacial
12.12 Add 3 drops of ammonium molybdate solution (11.2),
acetic acid. Mix again and add sufficient HCl (sp gr 1.19) to
0.5 g of KF (11.10) (if iron is present), 0.5 g of KI (11.11), mix
adjust the pH to 4.0. Store in a glass-stoppered bottle. Starch
until dissolved, and acidify with 15 mL of HCl (1 + 1) (11.6).
solution prepared in this manner will remain chemically stable
12.13 Titrate the sample (12.7) for iodide or the sample
for at least 1 year.
(12.12) for combined iodide and bromide with 0.01 N sodium
11.18.1 If a proprietary starch indicator powder is used, it
thiosulfate solution (11.17) using starch indicator (11.18).
shall be so indicated in reporting the results of the analysis.
Disregard any return of blue color after the endpoint.
11.19 Filter Paper—Purchase suitable filter paper. The user
must first ascertain that the filter paper is of sufficient purity to
13. Calculation
use without adversely affecting the bias and precision of the
13.1 Calculate the concentration of iodide and bromide ions
test method.
in milligrams per litre as follows:
13.2 Iodide:
12. Procedure
C 5 E 2 D
12.1 To remove iron, manganese, and organic matter from
the sample, add exactly 100 mL of sample to a bottle. Add 1 g
where:
of calcium oxide (11.5), stopper, and place the mixture in a
C = corrected millilitres of Na S O solution,
2 2 3
shaker for 1 h. Allow the mixture to stand overnight and filter
E = millilitres of Na S O , sample solution, and
2 2 3
on a dry folded filter (11.19), discarding the first 20 mL that
D = millilitres of Na S O blank solution.
2 2 3
come through. Brines with specific gravities less than 1.009
CN
may be filtered without standing overnight. Prepare a blank in 2
I , mg/L 5 × 21150
S
the same manner.
where:
12.2 Transfer an aliquot of the filtrate containing 1 mg to 2
mg of iodide to a 250-mL Erlenmeyer flask. Add sufficient N = normality of Na S O solution, and
2 2 3
S = millilitres of sample.
water to provide a total volume of 75 mL.
12.3 Add 3 drops of methyl red indicator (11.9). Add HCl 13.3 Bromide:
(1 + 199) (11.8) dropwise until the mixture is just slightly acid.
C 5 E 2 D
12.4 Add 10 mL of sodium acetate solution (11.12), 1 mL of
CN
Br , mg/L 5 × 13320 2 X
glacial acetic acid (11.1), 4 mL of bromine water (11.3), and
S
allow to stand for 5 min.
where:
12.5 Add 2 mL of sodium formate solution (11.14), blow
−
X = concentration of I as determined above.
out any bromine vapor from the neck of the flask, and wash
down the sides with water. 5
14. Precision and Bias
12.6 When the solution is completely colorless, add 0.2 g of
14.1 The overall precision (S ) and single-operator preci-
T
KF (11.10) and 0.5 g of KI (11.11). Mix until dissolved and add
sion (S ) of this test method within their designated ranges vary
o
15 mL of HCl (1 + 1) (11.6).
with the quantity being tested in accordance with Table 1 and
12.7 For final treatment and titration of the sample, proceed Table 2.
as directed in (12.13).
14.2 The bias of the test method determined from recoveries
12.8 To determine the combined iodide and bromide, trans- of known amounts of iodide and bromide in a series of
fer an aliquot of the filtrate (12.1) containing 1 mg to 2 mg of prepared standards are given in Table 1 and Table 2.
bromide to a 250-mL Erlenmeyer flask. Add sufficient water to
NOTE 2—The precision and bias estimates are based on the interlabo-
make the total volume 75 mL.
ratory study on four artificial brine samples containing various amounts of
iodide, bromide, and interfering ions as shown in Table 3. Two analysts in
12.9 If necessary add sufficient NaCl (11.13) to produce a
3-g chloride content. Add, in order, 10 mL of sodium hypo-
chlorite solution (11.15) and approximately 0.4 g of CaCO
3 5
Supporting data have been filed at ASTM International Headquarters and may
(11.4) (or enough so that approximately 0.1 g will remain after
be obtained by requesting Research Report RR:D19-1061. Contact ASTM Customer
the next step). Service at [e-mail].
D3869 − 15 (2023)
TABLE 1 Determination of Precision and Bias of Iodide Ions,
15.3 Initial Demonstration of Laboratory Capability:
Volumetric Methods
15.3.1 If a laboratory has not performed the test before, or if
Statistically
there has been a major change in the measurement system, for
Amount Added, Amount Significant (95 %
S S ±Bias
O T example, new analyst, new instrument, and so forth, a precision
mg/L Found, mg/L Confidence
Level) and bias study must be performed to demonstrate laboratory
12.1 11.4 1 1 −5.78 yes
capability.
116.3 112.5 2 3 −3.27 yes
15.3.2 Analyze seven replicates of a known solution pre-
771 743 12 15 +2.63 no
pared from an Independent Reference Material containing a
1375 1282 40 73 −6.76 yes
mid-range concentration of iodide and bromide. The matrix
and chemistry of the solution should be equivalent to the
TABLE 2 Determination of Precision and Bias of Bromide Ions,
solution used in the collaborative study. Each replicate must be
Volumetric Method
taken through the complete analytical test method including
Amount Statistically
any sample preservation and pretreatment steps.
Amount Added,
Found, S S ±Bias Significant (95 %
O T
mg/L
15.3.3 Calculate the mean and standard deviation of the
mg/L Confidence Level)
seven values and compare to the acceptable ranges of bias in
30.3 31.7 1 5 +4.62 yes
534 531 15 25 −0.56 no Table 1 and Table 2. This study should be repeated until the
1286 1249 23 182 −2.88 no
recoveries are within the limits given in Table 1 and Table 2. If
5734 5688 65 227 −0.80 no
a concentration other than the recommended concentration is
used, refer to Practice D5847 for information on applying the
F test and t test in evaluating the acceptability of the mean and
TABLE 3 Composition of Artificial Brine Samples
standard deviation.
mg/L
Sample
No.
15.4 Laboratory Control Sample (LCS):
1 2 3 4
I 12.1 116.3 771 1 375 15.4.1 To ensure that the test method is in control, prepare
and analyze a LCS containing a mid-range concentration of
Br 30.3 534 1 286 5 734
iodide and bromide with each batch (laboratory-defined or 20
Na 9 500 65 000 31 000 75 000
K 300 1 400 2 000 5 000 samples). the laboratory control samples for a large batch
Ca 550 1 000 700 2 000
should cover the analytical range when possible. It is
Mg 1 200 1 200 500 250
recommended, but not required to use a second source, if
Ba 30 650 300 300
Cl 19 000 107 000 52 000 121 000
possible and practical for the LCS. The LCS must be taken
through all of the steps of the analytical method including
sample preservation and pretreatment. The result obtained for
each of three laboratories performed duplicate determinations on each of
the LCS shall fall within 615 % of the known concentration.
2 days. Practice D2777 was used in developing these precision and bias
15.4.2 If the result is not within these limits, analysis of
estimates.
samples is halted until the problem is corrected, and either all
14.3 Precision and bias for this test method conforms to
the samples in the batch must be reanalyzed, or the results must
Practice D2777 – 77, which was in place at the time of
be qualified with an indication that they do not fall within the
collaborative testing. Under the allowances made in 1.4 of
performance criteria of the test method.
Practice D2777 – 13, these precision and bias data do meet
15.5 Method Blank:
existing requirements for interlaboratory studies of Committee
15.5.1 Analyze a reagent water test blank with each
D19 test methods.
laboratory-defined batch. The concentration of iodide and
15. Quality Control
bromide found in the blank should be less than 0.5 times the
reporting level. If the concentration of iodide and bromide is
15.1 In order to be certain that analytical values obtained
found above this level, analysis of samples is halted until the
using these test methods are valid and accurate within the
contamination is eliminated, and a blank shows no contamina-
confidence limits of the test, the following QC procedures must
tion at or above this level, or the results must be qualified with
be followed when analyzing iodide and bromide.
an indication that they do not fall within the performance
15.2 Calibration and Calibration Verification:
criteria of the test method.
15.2.1 Verify the sodium thiosulfate solution (11.17) ac-
15.6 Matrix Spike (MS):
cording to Practice E200.
15.6.1 To check for interferences in the specific matrix
15.2.2 Verify solution by analyzing a sample at the concen-
being tested, perform a MS on at least one sample from each
tration of a mid-range standard should fall within 615 % of the
laboratory-defined batch by spiking an aliquot of the sample
known concentration.
with a known concentration of iodide and bromide and taking
15.2.3 If calibration cannot be verified, remake the sodium
it through the analytical method.
thiosulfate solution.
15.2.4 It is recommended to analyze a blank and continuing 15.6.2 The spike concentration plus the background concen-
calibration verification (CCV) at a 10 % frequency. The results tration of iodide and bromide must not exceed the high
should fall within the expected precision of the method or 615 calibration standard. The spike must produce a concentration in
% of the known concentration. the spiked sample that is 2 to 5 times the analyte concentration
D3869 − 15 (2023)
in the unspiked sample, or 10 to 50 times the detection limit of 17. Summary of Test Method
the test method, whichever is greater.
17.1 Iodide in the sample is oxidized with nitrous acid and
15.6.3 Calculate the percent recovery of the spike (P) using
extracted into carbon tetrachloride. The concentration is pro-
the following calculation:
portional to the intensity of the purple color measured at 517
nm.
P 5 100 A V 1V 2 BV /CV
@ ~ ! #
s s
where:
18. Interference
A = analyte concentration (mg/L) in spiked sample;
18.1 Hydrocarbons that might interfere with the spectropho-
B = analyte concentration (mg/L) in unspiked sample;
tometric measurement can be removed from the sample by a
C = concentration (mg/L) of analyte in spiking solution;
carbon tetrachloride extraction.
V = volume (mL) of sample used; and
s
V = volume (mL) of spiking solution added.
18.2 Hydrogen sulfide can interfere and is removed by
boiling an acidified sample.
15.6.4 The percent recovery of the spike shall fall within the
limits, based on the analyte concentration, listed in Guide
19. Apparatus
D5810, Table 1. If the percent recovery is not within these
limits, a matrix interference may be present in the sample
19.1 Spectrophotometer or filter photometer having a light
selected for spiking. Under these circumstances, one of the path of approximately 10 mm for use at 517 nm. Filters, when
following remedies must be employed: the matrix interference required, shall be green, have a narrow-band pass, and a
maximum transmittance at or about this wavelength. Photom-
must be removed, all samples in the batch must be analyzed by
eters and photometric practices prescribed in this method shall
a test method not affected by the matrix interference, or the
conform to Practice E60. Spectrophotometers shall conform to
results must be qualified with an indication that they do not fall
Practice E275.
within the performance criteria of the test method.
19.2 Chemical (Filters) Funnel, approximate inside diam-
NOTE 3—Acceptable spike recoveries are dependent on the concentra-
eter of top of funnel 45 mm.
tion of the component of interest. See Guide D5810 for additional
information.
19.3 Separatory Funnel, 125-mL capacity, borosilicate glass
with a TFE-fluorocarbon stopcock and a linear high-density
15.7 Duplicate:
polyethylene stopper.
15.7.1 To check the precision of sample analyses, analyze a
sample in duplicate with each laboratory-defined batch. If the 19.4 Volumetric Flask, 50-mL capacity, borosilicate glass,
with a linear high-density polyethylene stopper.
concentration of the analyte is less than five times the detection
limit for the analyte, a matrix spike duplicate (MSD) should be
19.5 Filter Paper, rapid qualitative, 70-mm diameter. The
used.
user must first ascertain that the filter paper is of sufficient
15.7.2 Calculate the standard deviation of the duplicate
purity to use without adversely affecting the bias and precision
values and compare to the precision in the collaborative study
of the test method.
using an F test. Refer to 6.4.4 of Practice D5847 for informa-
19.6 Buret, precision-bore, micro, 10-mL capacity with a
tion on applying the F test.
TFE-fluorocarbon stopcock.
15.7.3 If the result exceeds the precision limit, the batch
must be reanalyzed or the results must be qualified with an
20. Reagents
indication that they do not fall within the performance criteria
20.1 Bromphenol Blue Indicator Solution (1 g/L)—Dissolve
of the test method.
0.1 g of water-soluble bromphenol blue in water and dilute to
15.8 Independent Reference Material:
100 mL.
15.8.1 In order to verify the quantitative value produced by
20.2 Carbon Tetrachloride (CCl ). (Warning—Avoid inha-
the test method, analyze an Independent Reference Material
lation and conduct all manipulation in a well-ventilated hood.)
(IRM) submitted as a regular sample (if practical) to the
20.3 Hydrochloric Acid (1 + 1)—Add 1 volume of HCl (sp
laboratory at least once per quarter. The concentration of the
gr 1.19) to 1 volume of water.
IRM should be in the concentration mid-range for the method
−
chosen. The value obtained must fall within the control limits
20.4 Iodide Solution, Standard (1 mL = 0.25 mg I )—Dry
established by the laboratory. about 3 g of potassium iodide (KI) crystals for 6 h at 105 °C.
Any large crystals should be crushed before drying, but not
TEST METHOD B—COLORIMETRIC FOR IODIDE
ground in a mortar for a long time. Dissolve 0.3270 g of the KI
in water and dilute to exactly 1 L in a volumetric flask.
16. Scope
Alternatively, certified iodide stock solutions are commercially
2 available through chemical supply vendors and may be used.
16.1 This test method covers the colorimetric determina-
tion of iodide in brackish water, seawater, and brines where
20.5 Potassium Nitrite Solution (100 g KNO /L)—Dissolve
concentrations range from 0.2 mg ⁄L to 2000 mg/L. 10 g of KNO in water and dilute to 100 mL.
D3869 − 15 (2023)
TABLE 4 Determination of Precision and Bias of Iodide Ions,
21. Calibration
Colorimetric Method
21.1 Using a microburet, to five 125-mL separatory funnels
Statistically
Amount
add respectively 0.0 (blank), 2.0, 4.0, 6.0, and 8.0-mL aliquots
Amount Significant (95 %
Found, S S ±Bias
O T
Added, mg/L Confidence
of standard iodide solution (20.4). Add sufficient water to bring
mg/L
Level)
the volume in each funnel to about 50 mL.
12.1 12.1 1 1 0.0 yes
116.3 119.2 10 15 +2.49 no
21.2 Follow 22.2 – 22.7.
771 786 58 63 +1.94 no
21.3 Prepare a calibration curve by plotting absorbance 1375 1488 160 225 +8.22 yes
against milligrams of iodide.
22. Procedure
24.2 The bias of the test method determined from recoveries
22.1 From the sample that is free of hydrocarbons and
of known amounts of iodide in a series of prepared standards
hydrogen sulfide, pipet an aliquot containing less than 2.5 mg
are given in Table 4.
of iodide into a separatory funnel and adjust the volume with
NOTE 4—The precision and bias estimates are based on an interlabo-
water to 50 mL.
ratory study on four artificial brine samples containing various amounts of
iodide and interfering ions as shown in Table 5. Two analysts in each of
22.2 Add 3 drops of bromphenol blue solution (20.1).
four laboratories performed duplicate determinations on each of two days.
22.3 Swirl the mixture and add HCl (1 + 1) (20.3) dropwise Practice D2777 was used in developing these precision and bias estimates.
until the indicator turns yellow (pH 5).
24.3 Precision and bias for this test method conforms to
Practice D2777 – 77, which was in place at the time of
22.4 Add 10 mL of carbon tetrachloride (20.2), 1 mL of
collaborative testing. Under the allowances made in 1.4 of
potassium nitrite solution (20.5), and mix by shaking the
Practice D2777– 13, these precision and bias data do meet
contents vigorously, relieving the pressure occasionally. (A
existing requirements for interlaboratory studies of Committee
violet color in the carbon tetrachloride phase indicates the
D19 test methods.
presence of iodide in the sample).
22.5 After the phases have separated drain the carbon
25. Quality Control
tetrachloride phase through a dry filter paper into a 50-mL
25.1 In order to be certain that analytical values obtained
volumetric flask.
using these test methods are valid and accurate within the
22.6 Repeat the extraction with two more 10-mL portions of
confidence limits of the test, the following QC procedures must
carbon tetrachloride (20.2) and drain through the same filter
be followed when analyzing iodide.
paper into the same volumetric flask (22.5).
25.2 Calibration and Calibration Verification:
25.2.1 Analyze at least four working standards containing
22.7 Dilute the combined extracts to 50 mL with carbon
tetrachloride (20.2). Measure the absorbance at 517 nm in a 10 concentrations of iodide that bracket the expected sample
nm transmittance cell using the blank extract as a reference concentration prior to analysis of samples to calibrate the
(see 21.3). The iodine-CCl solution is fairly stable. However, instrument.
avoid undue delay unless precautions are taken to prevent 25.2.2 Verify instrument calibration after standardization by
evaporation of the CCl . analyzing a standard at the concentration of one of the
calibration standards. The absorbance shall fall within 4 % of
the absorbance from the calibration. Alternately, the concen-
23. Calculation
tration of a mid-range standard should fall within 615 % of the
23.1 From the analytical curve (see 21.3) determine the
known concentration. Analyze a blank to verify cleanliness.
milligrams of iodide corresponding to the absorbance obtained
25.2.3 If calibration cannot be verified, recalibrate the
for each sample.
instrument.
23.2 Calculate the concentration of iodide ion in the sample, 25.2.4 It is recommended to analyze a continuing calibra-
in milligrams per litre, as follows: tion blank (CCB) and continuing calibration verification
(CCV) at a 10 % frequency. The results should fall within the
M × 1000
I , mg/L 5
expected precision of the method or 615 % of the known
S
concentration.
where:
25.3 Initial Demonstration of Laboratory Capability:
1000 = 1000 mL / litre
25.3.1 If a laboratory has not performed the test before, or if
M = milligrams of iodide from curve, and
there has been a major change in the measurement system, for
S = millilitres of sample.
example, new analyst, new instrument, and so forth, a precision
and bias study must be performed to demonstrate laboratory
24. Precision and Bias
capability.
24.1 The overall precision (S ) and single-operator preci- 25.3.2 Analyze seven replicates of a standard solution
T
sion ( S ) of this test method within their designated ranges prepared from an Independent Reference Material containing a
o
vary with the quantity being tested in accordance with Table 4. mid-range concentration of iodide. The matrix and chemistry
...