ASTM D5085-21

Standard Test Method for Determination of Chloride, Nitrate, and Sulfate in Atmospheric Wet Deposition by Suppressed Ion Chromatography

SIGNIFICANCE AND USE
5.1 This test method is for the determination of the anions: chloride, nitrate, and sulfate in atmospheric wet deposition.  
5.2 Fig. X1.1 in the appendix represents cumulative frequency percentile concentration plots of chloride, nitrate, and sulfate obtained from analyses of over 5000 wet deposition samples. These data may be used as an aid in the selection of appropriate calibration solutions (2).
SCOPE
1.1 This test method is applicable to the determination of chloride, nitrate, and sulfate in atmospheric wet deposition samples (rain, snow, sleet, and hail) by suppressed ion chromatography. For additional applications, see to Test Method D4327.  
1.2 The concentration ranges for this test method are as listed below. The range tested was confirmed using the interlaboratory collaborative test (see Table 1 for statistical summary of the collaborative test).    
Method
Detection
L (mg/L) (1)  
Range of
Method
(mg/L)  
Range
Tested
(mg/L)  
Chloride  
0.03  
0.09–2.0  
0.15–1.36  
Nitrate  
0.03  
0.09–5.0  
0.15–4.92  
Sulfate  
0.03  
0.09–8.0  
0.15–6.52  
1.3 The method detection limit (MDL) is based on single operator precision (1)2 and may be higher or lower for other operators and laboratories. The precision and bias data presented are insufficient to justify use at this low level; however, it has been reported that this test method is reliable at lower levels than those that were tested. The MDLs listed above were determined following the guidance in 40 CFR Part 136 Appendix B. Other approaches to the determination of MDLs may yield different MDLs.  
1.4 Method Detection Limits will vary depending on the type and length of column(s) used, the composition and strength of eluent used, the bore size of the instrumentation (that is, microbore or standard bore), eluent flow rate and other variables between instruments. The method detection limits listed above are those used in determining the Precision and Bias of this method as given in Table 1.  
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. Specific precautionary statements are given in Section 9.  
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-Aug-2021
• ICS: 07.060 - Geology. Meteorology. Hydrology
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.03 - Ambient Atmospheres and Source Emissions

Relations

• Refers: ASTM E694-18(2024) - Standard Specification for Laboratory Glass Volumetric Apparatus
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D1356-20a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 01-Sep-2020
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D1356-20 - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Mar-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM E694-18 - Standard Specification for Laboratory Glass Volumetric Apparatus
• Effective Date: 01-Jan-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM D1356-15a - Standard Terminology Relating to Sampling and Analysis of Atmospheres
• Effective Date: 15-Oct-2015

Overview

ASTM D5085-21 is an internationally recognized standard that details a reliable test method for the determination of chloride, nitrate, and sulfate anions in atmospheric wet deposition. Employing chemically suppressed ion chromatography, this standard enables precise measurement of these anions in rain, snow, sleet, and hail. Accurate analysis of such ions is essential for air quality monitoring, environmental impact studies, and regulatory compliance.

The scope of ASTM D5085-21 encompasses concentrations typically found in ambient atmospheric deposition, supporting laboratories, research institutions, and environmental monitoring networks worldwide. The standard addresses method calibration, interference mitigation, instrument setup, and calculation and reporting protocols, making it a comprehensive resource for environmental chemists and analysts.

Key Topics

• Applicable Sample Types: Atmospheric wet deposition, including rain, snow, sleet, and hail.
• Analytes: Chloride, nitrate, and sulfate anions.
• Analytical Technique: Suppressed ion chromatography, utilizing ion exchange columns with conductivity detection.
• Concentration Ranges:
  • Chloride: 0.09–2.0 mg/L (tested range: 0.15–1.36 mg/L)
  • Nitrate: 0.09–5.0 mg/L (tested range: 0.15–4.92 mg/L)
  • Sulfate: 0.09–8.0 mg/L (tested range: 0.15–6.52 mg/L)
• Detection Limit: Method detection limits (MDLs) are typically 0.03 mg/L for each analyte, but may vary by laboratory, operator, and instrument configuration.
• Calibration: Emphasizes the use of multiple calibration solutions and quality control standards to ensure accurate, traceable results.
• Sample Handling: Provides detailed requirements for sample collection, preservation, and preparation to minimize contamination and analyte degradation.
• Quality Assurance: Includes guidelines on instrument performance checks, repeatability, reproducibility, and bias assessment.

Applications

• Air Quality Monitoring: Facilitates tracking of atmospheric deposition of acidic and reactive anions, critical for understanding trends in acid rain and regional air pollution.
• Environmental Impact Assessment: Supports studies on the cycling of nutrients and contaminants, helping quantify depositions that may affect ecosystems, soils, and water bodies.
• Regulatory Compliance: Assists laboratories and agencies in complying with guidelines and reporting requirements related to atmospheric deposition and wet chemistry measurements.
• Research and Academic Studies: Used in academic research to compare wet deposition chemistry across geographic regions or over time.
• Networked Monitoring Programs: Integral to large-scale atmospheric monitoring networks that collect and analyze wet deposition samples, informing policy and environmental management.

Related Standards

• ASTM D4327: Standard Test Method for Anions in Water by Suppressed Ion Chromatography, offering additional application coverage.
• ASTM D1193: Specification for Reagent Water, ensuring reagent water quality.
• ASTM D1356: Terminology Relating to Sampling and Analysis of Atmospheres.
• ASTM D2777: Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water.
• ASTM D5012: Practice for Preparation of Materials Used for Collection and Preservation of Atmospheric Wet Deposition.
• ASTM E694: Specification for Laboratory Glass Volumetric Apparatus, relevant to precise volumetric measurements.
• 40 CFR Part 136 Appendix B: U.S. EPA guidance for determination of method detection limit, referenced for MDL procedures.

Practical Value

Adopting ASTM D5085-21 ensures the generation of high-quality, reproducible data when analyzing chloride, nitrate, and sulfate in wet deposition samples. By establishing method consistency and promoting best practices for sample handling and analysis, laboratories enhance data credibility and support robust environmental decision-making. The standard is especially valuable for organizations involved in atmospheric deposition monitoring, regulatory enforcement, and long-term air quality assessment programs.

Keywords: atmospheric wet deposition, chloride, nitrate, sulfate, ion chromatography, ASTM D5085, environmental monitoring, air quality, wet precipitation analysis, acid rain, suppressed ion chromatography.

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: D5085 − 21
Standard Test Method for
Determination of Chloride, Nitrate, and Sulfate in
Atmospheric Wet Deposition by Suppressed Ion
Chromatography
This standard is issued under the fixed designation D5085; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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
safety concerns, if any, associated with its use. It is the
1.1 This test method is applicable to the determination of
responsibility of the user of this standard to establish appro-
chloride, nitrate, and sulfate in atmospheric wet deposition
priate safety, health, and environmental practices and deter-
samples (rain, snow, sleet, and hail) by suppressed ion chro-
mine the applicability of regulatory limitations prior to use.
matography. For additional applications, see to Test Method
Specific precautionary statements are given in Section 9.
D4327.
1.6 This international standard was developed in accor-
1.2 The concentration ranges for this test method are as dance with internationally recognized principles on standard-
listed below. The range tested was confirmed using the
ization established in the Decision on Principles for the
interlaboratory collaborative test (see Table 1 for statistical Development of International Standards, Guides and Recom-
summary of the collaborative test).
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
Method Range of Range
Detection Method Tested
L (mg/L) (1) (mg/L) (mg/L)
2. Referenced Documents
Chloride 0.03 0.09–2.0 0.15–1.36
Nitrate 0.03 0.09–5.0 0.15–4.92
2.1 ASTM Standards:
Sulfate 0.03 0.09–8.0 0.15–6.52
D883Terminology Relating to Plastics
1.3 The method detection limit (MDL) is based on single
D1129Terminology Relating to Water
operator precision (1) and may be higher or lower for other
D1193Specification for Reagent Water
operators and laboratories. The precision and bias data pre-
D1356Terminology Relating to Sampling and Analysis of
sented are insufficient to justify use at this low level; however,
Atmospheres
it has been reported that this test method is reliable at lower
D2777Practice for Determination of Precision and Bias of
levelsthanthosethatweretested.TheMDLslistedabovewere
Applicable Test Methods of Committee D19 on Water
determined following the guidance in 40 CFR Part 136
D3670Guide for Determination of Precision and Bias of
Appendix B. Other approaches to the determination of MDLs
Methods of Committee D22
may yield different MDLs.
D4210Practice for Intralaboratory Quality Control Proce-
dures and a Discussion on Reporting Low-Level Data
1.4 Method Detection Limits will vary depending on the
(Withdrawn 2002)
type and length of column(s) used, the composition and
D4327Test Method forAnions in Water by Suppressed Ion
strength of eluent used, the bore size of the instrumentation
Chromatography
(thatis,microboreorstandardbore),eluentflowrateandother
D5012Practice for Preparation of Materials Used for the
variables between instruments. The method detection limits
Collection and Preservation of Atmospheric Wet Deposi-
listed above are those used in determining the Precision and
tion
Bias of this method as given in Table 1.
E694Specification for Laboratory Glass Volumetric Appa-
ratus
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2021. Published April 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 2013 as D5085–02 (2013). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5085-21. the ASTM website.
2 4
The boldface numbers in parentheses refer to references at the end of this test The last approved version of this historical standard is referenced on
method. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5085 − 21
E1154Specification for Piston or Plunger Operated Volu- decreasing the eluent concentration or flow rate, or decreasing
metric Apparatus sample size will result in improved peak resolution.
IEEE/ASTM SI-10Standard for Use of the International
6.3 Water in the sample will cause a negative peak (“water
System of Units (SI): The Modern Metric System
dip”) in the chromatogram when it elutes because its conduc-
2.2 Other Documents:
tance is less than that of the suppressed eluent. Depending on
40 CFR 136 Appendix BDefinition and Procedure for the
the column used, chloride may elute near the water dip and
Determination of the Method Detection Limit
must be sufficiently resolved from the dip to be accurately
quantified. This can be achieved by changing the eluent
3. Terminology
concentration or decreasing the flow rate. The potential inter-
3.1 Definitions—For definitions of terms used in this test
ference of the negative peak can be eliminated by adding an
method, refer to Terminologies D883, D1129, and D1356 and
equivalentof100µLofapreparedeluentconcentrate(solution
Test Method D4327 and Practice IEEE/ASTM SI-10.
that is 100 times more concentrated than the eluent used for
analysis) per 10.0 mL of sample. Identical eluent additions
4. Summary of Test Method
must also be included in calibration and quality control
4.1 Ionchromatographycombinesconductimetricdetection solutions.
with the separation capabilities of ion exchange resins. A
6.4 Decreases in retention times and resolution are symp-
filteredaliquotofthesample,ranginginsizefrom5to250µL,
toms of column deterioration.
depending on instrumental system, is pumped through an ion
6.5 Contaminated valves and sample lines may reduce
exchange column where the anions of interest are separated.
system performance causing decreased retention times and
Each ion is identified by its retention time within the exchange
resolutions. Refer to the manufacturer’s guidelines for instruc-
column.Thesampleionsareselectivelyelutedofftheseparator
tions on cleaning the valves and replacing the lines.
column and into a suppressor, where the conductivity of the
eluent ions is reduced and the sample ions are converted to
NOTE 1—Review operational details and refer to the trouble shooting
their corresponding strong acids. The separated anions are
guide in the Operator’s Manual to determine the cause of decreased
detected by a conductivity detector. Data is collected using retention times and resolution prior to extensive cleaning or changing of
all valves, columns, filters, sample lines, or all of the above.
acquisition software specific to the system in use. Measure-
ment of peak area is used for quantitation. The ion chromato-
6.6 The presence of air bubbles in the columns, tubing, or
graph is calibrated with standard solutions containing known
conductivity detector cell may cause baseline fluctuations and
concentrations of the anion(s) of interest. Calibration curves
peak variability. The use of degassed water for eluents and
areconstructedfromwhichtheconcentrationofeachanalytein
regenerants minimizes the introduction of air (See 8.2).
the unknown sample is determined. For additional information
6.7 For more information on interferences refer to Test
on ion chromatography refer to Test Method D4327.
Method D4327.
5. Significance and Use
7. Apparatus
5.1 This test method is for the determination of the anions:
7.1 Ion Chromatograph (IC)—Select an instrument
chloride, nitrate, and sulfate in atmospheric wet deposition.
equippedwithaninjectionvalve,asampleloop,guardcolumn,
5.2 Fig. X1.1 in the appendix represents cumulative fre-
separator column, suppressor, pump(s), conductivity detector,
quency percentile concentration plots of chloride, nitrate, and
and suitable data acquisition software. An autosampler is
sulfate obtained from analyses of over 5000 wet deposition
recommended. Compressed gas, typically high purity helium
samples. These data may be used as an aid in the selection of
or nitrogen, may be required for some IC systems.
appropriate calibration solutions (2).
7.1.1 Tubing—Tubing that comes in contact with samples
and standards must be manufactured from inert material such
6. Interferences
as polyethylethylketone (PEEK) or tetrafluoroethylene (TFE).
6.1 Unresolved peaks will result when the concentration of
7.1.2 Anion Guard Column—Located upstream from the
one of the sample components is 10 to 20 times higher than
separator column. The guard column is used to protect the
another component that appears in the chromatogram as an
separator column from being fouled by particulates or organic
adjacentpeak.Decreasingtheeluentconcentrationorflowrate,
constituents.
diluting the sample with reagent water, or decreasing sample
7.1.3 Anion Separator Column—This column is generally
injection volume may correct this problem.
packed with a pellicular low-capacity anion exchange resin.
6.2 Interferences may be caused by ions with retention
7.1.4 Anion Suppressor Column—Place between the sepa-
times that are similar to the anion of interest. Before analyzing
rator column and the detector.
precipitation samples, determine the retention times of these
7.1.5 Compressed Helium—High purity grade.
possibleinterferingions.Interferenceiscommoninsometypes
7.1.6 Detector—A flow-through, temperature-compensated,
of wet deposition samples. If interference is anticipated,
electrical conductivity cell.
7.1.7 Pump—Capable of delivering a constant flow rate.
Flow rates and back pressures are dependent on the specific
Available from U.S. Government Publishing Office (GPO), 732 N. Capitol St.,
NW, Washington, DC 20401, http://www.gpo.gov. manufacturer’s IC system.All interior pump surfaces that will
D5085 − 21
beincontactwithsamplesandstandardsmustbemanufactured 8.5 Stock Standard Solutions—NIST-traceable
from inert, non-metallic materials. commercially-prepared 1000 mg/L solutions of chloride, ni-
7.1.8 Data Acquisition System—A computer operating trate and sulfate.
system-specific acquisition software to collect and process
8.6 Sample Containers—Use analyte-free glass, high den-
data.
sitypolyethylene(HDPE)orlowdensitypolyethylene(LDPE)
7.1.9 Sample Loop—Selectasampleloopwithacapacityof
containers. Containers include both autosampler vials and any
5 to 250 µL.
bottles that may be used in the transportation of the sample.
7.1.10 Autosampler—An autosampling system capable of
9. Hazards
precise delivery.
9.1 The calibration standards, sample types, and most re-
7.2 Eluent and Regenerant Reservoirs—Select containers
agents used in this test method pose limited hazard to the
witha4to20L capacity that are designed to minimize
analyst when following typical laboratory safety practices (see
introduction of air into the flow system for storing eluents and
9.2).
regenerants. Reservoirs may be blanketed with helium or
nitrogen per manufacturer’s guidelines. 9.2 Follow American Chemical Society guidelines regard-
ing the safe handling of chemicals used in this test method (3).
7.3 Labware—Glasswareorplasticware,includingvolumet-
ric pipettes and flasks, must be dedicated only for use with
10. Sampling, Sample Preservation and Test Units
atmospheric wet deposition samples. Volumetric glassware or
10.1 Some chemical constituents found in atmospheric wet
plasticware must meet the requirement for ClassAitems given
deposition are not stable and must be preserved before analy-
in Specification E694.
sis. Proper selection and cleaning of sampling containers are
required to reduce the possibility of contamination (2).
NOTE 2—More sensitive instruments may have issues with contamina-
tion from borosilicate glassware. High density polyethylene (HDPE), low
10.2 For additional information on sample collection and
density polyethylene (LDPE), or polystyrene is a suitable alternative to
preservation of atmospheric wet deposition refer to Guide
glass volumetrics.
D5012.
7.4 Pipettes—Fully adjustable, air-displacement pipets, for
– – 2–
10.3 Data are reported in mg/L as CL,NO ,orSO .
small-volumedispensingofaqueousfluidsofmoderateviscos- 3 4
ity and density. Pipets must comply with Specification E1154
11. Calibration and Standardization
for piston operated volumetric devices.
11.1 Determination of Retention Times:
11.1.1 The retention time for each anion is determined by
8. Reagents and Materials
injecting a standard solution containing
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5085 − 02 (Reapproved 2013) D5085 − 21
Standard Test Method for
Determination of Chloride, Nitrate, and Sulfate in
Atmospheric Wet Deposition by Chemically Suppressed Ion
Chromatography
This standard is issued under the fixed designation D5085; 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
1.1 This test method is applicable to the determination of chloride, nitrate, and sulfate in atmospheric wet deposition samples (rain,
snow, sleet, and hail) by chemically suppressed ion chromatographychromatography. (1).For additional applications
referapplications, see to Test Method D4327.
1.2 The concentration ranges for this test method are as listed below. The range tested was confirmed using the interlaboratory
collaborative test (see Table 1Table 1 for statistical summary of the collaborative test).
Range of Range
MDL Method Tested
(mg/L) (2) (mg/L) (mg/L)
Method Range of Range
Detection Method Tested
L (mg/L) (1) (mg/L) (mg/L)
Chloride 0.03 0.09–2.0 0.15–1.36
Nitrate 0.03 0.09–5.0 0.15–4.92
Sulfate 0.03 0.09–8.0 0.15–6.52
1.3 The method detection limit (MDL) is based on single operator precision (21) and may be higher or lower for other operators
and laboratories. The precision and bias data presented are insufficient to justify use at this low level, however, many workers have
foundlevel; however, it has been reported that this test method is reliable at lower levels than those that were tested. The MDLs
listed above were determined following the guidance in 40 CFR Part 136 Appendix B. Other approaches to the determination of
MDLs may yield different MDLs.
1.4 Method Detection Limits will vary depending on the type and length of column(s) used, the composition and strength of eluent
used, the bore size of the instrumentation (that is, microbore or standard bore), eluent flow rate and other variables between
instruments. The method detection limits listed above are those used in determining the Precision and Bias of this method as given
in Table 1.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 9.
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 Oct. 1, 2013Sept. 1, 2021. Published October 2013April 2022. Originally approved in 1990. Last previous edition approved in 20082013 as
D5085 – 02 (2008).(2013). DOI: 10.1520/D5085-02R13.10.1520/D5085-21.
The boldface numbers in parentheses refer to references at the end of this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5085 − 21
TABLE 1 Precision and Bias for Chloride, Nitrate, and Sulfate Determined from the Synthetic Atmospheric Wet Deposition Samples
Used in the Interlaboratory Comparison Study
Precision mg/L
Amount Mean
Bias, Significant
A 95 % 95 %
Analyte Added, Recovery, n
B
C D
mg/L Bias
S Reproducibility S Repeatability
t o
mg/L mg/L
Limit Limit
Chloride 0.15 0.157 36 0.0535 0.150 0.0116 0.0325 0.007 no
0.30 0.293 35 0.0554 0.155 0.0291 0.0815 −0.007 no
0.68 0.652 36 0.0549 0.154 0.0237 0.0664 −0.028 biased low
1.36 1.368 36 0.1 0.28 0.0431 0.121 0.008 no
Nitrate 0.15 0.138 24 0.0362 0.101 0.0289 0.0809 −0.012 no
1.08 1.077 24 0.0495 0.139 0.0421 0.118 −0.003 no
2.44 2.486 22 0.0197 0.0552 0.0183 0.0512 0.046 biased high
4.92 4.999 24 0.126 0.353 0.075 0.21 0.079 biased high
Sulfate 0.15 0.172 36 0.055 0.154 0.0304 0.085 0.022 no
1.43 1.442 35 0.0683 0.191 0.0369 0.103 0.012 no
3.23 3.358 36 0.13 0.364 0.046 0.129 0.128 biased high
6.52 6.775 36 0.37 1.04 0.109 0.305 0.255 biased high
A
Number of samples included in final statistical analysis after removal of outlier data.
B
95 % confidence level.
C
Between laboratory precision, reproducibility.
D
Within laboratory precision (pooled single operator precision), repeatability.
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.
2. Referenced Documents
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D3670 Guide for Determination of Precision and Bias of Methods of Committee D22
D4210 Practice for Intralaboratory Quality Control Procedures and a Discussion on Reporting Low-Level Data (Withdrawn
2002)
D4327 Test Method for Anions in Water by Suppressed Ion Chromatography
D5012 Practice for Preparation of Materials Used for the Collection and Preservation of Atmospheric Wet Deposition
E694 Specification for Laboratory Glass Volumetric Apparatus
E1154 Specification for Piston or Plunger Operated Volumetric Apparatus
IEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System
2.2 Other Documents:
40 CFR 136 Appendix B Definition and Procedure for the Determination of the Method Detection Limit
3. Terminology
3.1 Definitions—For definitions of terms used in this test method, refer to Terminologies D883, D1129, and D1356 and Test
Method D4327 and Practice IEEE/ASTM SI-10.
4. Summary of Test Method
4.1 Ion chromatography combines conductometricconductimetric detection with the separation capabilities of ion exchange
resins. (1)A filtered aliquot of the sample, ranging in size from 505 to 250 μL, depending on instrumental system, is pumped
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Dionex P/N 030986 (AG3) available from Dionex Corp., 1228 Titan Way, PO Box 3603, Sunnyvale, CA, 94088-3603, or equivalent has been found to be
satisfactory.Available from U.S. Government Publishing Office (GPO), 732 N. Capitol St., NW, Washington, DC 20401, http://www.gpo.gov.
D5085 − 21
through an ion exchange column where the anions of interest are separated. Each ion’s affinity for the exchange sites, known as
its selectivity quotient, is largely determined by its radius and valence. Because different ions have different selectivity quotients,
the sample ions elute from the column as discrete bands. Each ion is identified by its retention time within the exchange column.
The sample ions are selectively eluted off the separator column and ontointo a suppressor column, suppressor, where the
conductivity of the eluent ions is reduced and the sample ions are converted to their corresponding strong acids. The separated
anions are detected by a conductance cell. The chromatograms produced are displayed on a strip chart recorder or other data
acquisition device. conductivity detector. Data is collected using acquisition software specific to the system in use. Measurement
of peak height or area is used for quantitation. The ion chromatograph is calibrated with standard solutions containing known
concentrations of the anion(s) of interest. Calibration curves are constructed from which the concentration of each analyte in the
unknown sample is determined. For additional information on ion chromatography refer to Test Method D4327.
5. Significance and Use
5.1 This test method is useful for the determination of the anions: chloride, nitrate, and sulfate in atmospheric wet deposition.
5.2 Fig. X1.1 in the appendix represents cumulative frequency percentile concentration plots of chloride, nitrate, and sulfate
obtained from analyses of over 5000 wet deposition samples. These data may be used as an aid in the selection of appropriate
calibration solutions (32).
6. Interferences
6.1 Unresolved peaks will result when the concentration of one of the sample components is 10 to 20 times higher than another
component that appears in the chromatogram as an adjacent peak. Decreasing the eluent concentration or flow rate, increasing
column length, diluting the sample with reagent water, or decreasing sample size injection volume may correct this problem.
6.2 Interferences may be caused by ions with retention times that are similar to the anion of interest. The retention time of sulfite
may be similar to nitrate or sulfate. Other possible interfering ions are bromide and phosphate. Before analyzing precipitation
samples, measuredetermine the retention times of these possible interfering ions. Interference is common in some types of wet
deposition samples. If this interference is anticipated, decreasing the eluent concentration or flow rate, increasing column length,
or decreasing sample size will result in improved peak resolution.
6.3 Water fromin the sample injection will cause a negative peak (water dip)(“water dip”) in the chromatogram when it elutes
because its conductance is less than that of the suppressed eluent. Chloride Depending on the column used, chloride may elute near
the water dip and must be sufficiently resolved from the dip to be accurately quantified. This can be achieved by changing the
eluent concentration or decreasing the flow rate. The potential interference of the negative peak can be eliminated by adding an
equivalent of 100 μlμL of a prepared eluent concentrate (solution that is 100 times more concentrated than the eluent used for
analysis) per 10.0 mL of sample. Identical eluent additions must also be included in calibration and quality control solutions.
6.4 Decreases in retention times and resolution are symptoms of column deterioration which may be caused by the buildup of
contaminants on the exchange resin. Refer to the manufacturer’s guidelines for instructions on cleaning the column resin and
column filter beds. Excising the contaminated portion of the column and changing the filters may also improve performance. If
the procedure in this section do not restore the retention times, replace the column.deterioration.
6.5 Contaminated valves and sample lines may also reduce system performance causing decreased retention times and resolutions.
Refer to the manufacturer’s guidelines for instructions on cleaning the valves and replacing the lines.
NOTE 1—Review operational details and refer to the trouble shooting guide in the Operator’s Manual to determine the cause of decreased retention times
and resolution prior to extensive cleaning or changing of all valves, columns, filters, sample lines, or all of the above.
6.6 The presence of air bubbles in the columns, tubing, or conductivity detector cell may cause baseline fluctuations and peak
variability. Prevent introducing air into the system when injecting samples and standards. The use of degassed water for eluents
and regenerants may help to minimize minimizes the introduction of air (See 8.2).
6.7 For more information on interferences refer to Test Method D4327.
D5085 − 21
7. Apparatus
7.1 Ion Chromatograph—Chromatograph (IC)—Select an instrument equipped with an injection valve, a sample loop, separator
column(s), suppressor column(s), pump(s), and detector meeting requirements specified. Peripheral equipment includes
compressed gas, a guard column, separator column, suppressor, pump(s), conductivity detector, and suitable data acquisition device
such as a strip chart recorder, an integrator, or computer, and may include an automatic sampler.software. An autosampler is
recommended. Compressed gas, typically high purity helium or nitrogen, may be required for some IC systems.
7.1.1 Tubing—Tubing that comes in contact with samples and standards must be manufactured from inert material such as
polyethylene plastics or TFE-fluorocarbon.polyethylethylketone (PEEK) or tetrafluoroethylene (TFE).
7.1.2 Anion Guard Column—Also called a precolumn, it is placed before Located upstream from the separator column. The guard
column contains the same resin as the separator column and is used to protect it the separator column from being fouled by
particulates or organic constituents. Using an anion guard column will prolong the life of the separator column.
7.1.3 Anion Separator Column—This column is a column generally packed with a pellicular low-capacity anion exchange resin
constructed of polystyrene-divinylbenzene beads coated with quartenary ammonium active sites.resin.
7.1.4 Anion Suppressor Column—Place followingbetween the separator column. This may be in the form of an anion
micro-membrane suppressor or an anion self-regenerating suppressor. The first type of suppressor utilizes a semipermeable
membrane containing anion exchange sites to suppress eluent conductance.column and the detector. The second type of suppressor
uses the neutralized cell effluent as the source of water for the regenerant chamber water.
7.1.5 Compressed Gas (Nitrogen or Air)—Helium—Use ultra-high purity 99.999 % (High purity grade.v/v) compressed gas that
is oil, particulate, and water free to actuate the valves and to pressurize the regenerant flow system as needed.
7.1.6 Detector—Select a A flow-through, temperature-compensated, electrical conductivity cell with a volume of approximately
6 μL coupled with a meter capable of reading from 0 to 1000 μs/cm on an analog or digital scale.cell.
7.1.7 Pump—Use a pump capable both Capable of delivering a constant flow rate of approximately 1 to 5 mL/min and of tolerating
a pressure 1379 to 13 790 kPa. A constant pressure, constant flow pump is recommended for enhanced baseline stability. rate. Flow
rates and back pressures are dependent on the specific manufacturer’s IC system. All interior pump surfaces that will be in contact
with samples and standards must be manufactured from inert, non-metallic materials.
7.1.8 Data Acquisition System: System—
7.1.8.1 Recorder—This must be compatible with the maximum conductance detector output with a full-scale response time of 0.5
s or less. A two pen recorder with variable voltage input settings is recommended.A computer operating system-specific acquisition
software to collect and process data.
7.1.8.2 Integrator—If an integrating system is employed, the data acquisition unit must be compatible with the maximum detector
output to quantitate the peak height or area. If an integrator is used, the maximum peak height or area measurement must be within
the linear range of the integrator.
7.1.9 Sample Loop—Select a sample loop with a capacity of 505 to 250 μL.
7.1.10 Sample Introduction System—Autosampler—Select one of the following:An autosampling system capable of precise
delivery.
7.1.10.1 Syringe—A syringe equipped with a male fitting with a minimum capacity of 2 mL.
7.1.10.2 Autosampler—An autosampling system capable of precise delivery, equipped with a dust cover to reduce airborne
contamination.
7.2 Eluent and Regenerant Reservoirs—Select containers with a 4 to 20 L capacity that are designed to minimize introduction of
air into the flow system for storing eluents and regenerants. Reservoirs may be blanketed with helium or nitrogen per
manufacturer’s guidelines.
D5085 − 21
7.3 Glassware—Labware—Glassware, Glassware or plasticware, including volumetric pipettes and flasks, must be dedicated only
for use onwith atmospheric wet deposition samples only. Volumetric pipettes should be used to measure the stock solutions. The
pipettes may be either fixed or variable volume and either glass or plastic. Volumetric glassware samples. Volumetric glassware
or plasticware must meet the requirement for Class A items given in Specification E694. Pipettes with disposable tips are preferred
in order to reduce contamination. The pipettes must have a precision and a bias of 1 % or better. Precision and bias are determined
by weighing a minimum of ten separately pipetted aliquots.
NOTE 2—More sensitive instruments may have issues with contamination from borosilicate glassware. High density polyethylene (HDPE), low density
polyethylene (LDPE), or polystyrene is a suitable alternative to glass volumetrics.
7.4 Laboratory Facilities—Pipettes—Laboratories used Fully adjustable, air-displacement pipets, for the analysis of wet
deposition samples must be free from sources of contamination. The use of laminar flow clean air work stations is recommended
for sample processing and preparation to avoid the introduction of airborne contaminants. Samples must always be capped
orsmall-volume dispensing of aqueous fluids of moderate viscosity and density. Pipets must comply with Specification E1154
covered prior to analysis. A positive pressure environment within the laboratory is also recommended to minimize the introduction
of external sources of contaminant gases and particulates. Room temperature fluctuations must be controlled to within 6°C to
prevent baseline drift and changes in detector response. Windows within the laboratory must be kept closed at all times and sealed
if air leaks are apparent. The use of disposable tacky floor mats at the entrance to the laboratory is helpful in reducing the
particulate loading within the room.for piston operated volumetric devices.
8. Reagents and Materials
8.1 Purity of Reagents—Use reagent grade or higher grade chemicals for all solutions. All reagents shall conform to the
specifications of the Committee on Analytical Reagents of the American Chemical Society (ACS) where such specifications are
available.
8.2 Purity of Water—Use water conforming to Specification D1193, Type II. Point of use 0.2 μm filters are recommended for all
faucets supplying water to prevent the introduction of bacteria, ion exchange resins, or both, into reagents, standard solutions, and
internally formulated quality control check solutions. If degassing is necessaryperformed (see 6.6), de-gas the water prior to use
by placing in a polyolefin or glass container, stirring vigorously, and aspirating off the liberated gasses.
8.3 Eluent Solution—Eluent—(The eluent solution given here is for use with the AS3 or AS4 separator column. Other columns
are available.) Sodium bicarbonate 0.0028 Eluent solutions are specific M, sodium carbonate 0.0022 M (eluent strength
recommended for wet deposition analysis). Dissolve 0.941 g sodium bicarbonate (NaHCO ) and 0.933 g of sodium carbonate
(Na CO ) in water and dilute to 4 L with water. Mix the solution well and de-gas before use when necessary.to the column being
2 3
used. Refer to column manufacturer’s instructions for eluent preparation. Automated eluent generators may be used.
8.4 Regeneration Solution: Regenerant—
8.4.1 Sulfuric Acid (0.009 M)—(Regenerate for the Anion Micro-Membrane Suppressor.) Add 2.02 mL of concentrated H SO to
2 4
2 L of water, mix well, and dilute to 4 L.Regenerant solutions are specific to the suppressor being used. Refer to manufacturer’s
instructions for regenerant preparation and use. Self-regenerating suppressors do not require a separate regenerant solution.
8.4.2 Water—Reagent water, ASTM Type I, for use with some supressors.
8.4.3 The self-regenerating supressors need no regenerant solution.
8.5 Stock Standard Solutions—Stock standard solutions may be purchased as certified solutions or prepared from ACS reagent
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