ASTM D5508-23

Standard Test Method for Determination of Residual Acrylonitrile Monomer in Styrene-Acrylonitrile Copolymer Resins and Nitrile-Butadiene Rubber by Headspace-Capillary Gas Chromatography (HS-CGC)

SIGNIFICANCE AND USE
4.1 A measurement of the residual acrylonitrile in nitrile rubbers (NBR), styrene-acrylonitrile copolymers or ABS terpolymers will determine the polymer's suitability for various applications.  
4.2 Under optimum conditions, the minimum level of detection of RAN in NBR, SAN, or ABS terpolymers is approximately 50 ppb.
SCOPE
1.1 This test method covers the determination of the residual acrylonitrile (RAN) content in nitrile-butadiene rubbers (NBR), styrene-acrylonitrile (SAN) copolymers, and rubber-modified acrylonitrile-butadiene-styrene (ABS) resins.  
1.2 Any components that can generate acrylonitrile in the headspace procedure will constitute an interference. The presence of 3-hydroxypropionitrile in latices limits this procedure to dry rubbers and resins.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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 6.3 and 6.4.
Note 1: There is no known ISO equivalent to this standard.  
1.5 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-Sep-2023
• ICS: 83.060 - Rubber
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.70 - Analytical Methods

Relations

• Replaces: ASTM D5508-16 - Standard Test Method for Determination of Residual Acrylonitrile Monomer in Styrene-Acrylonitrile Copolymer Resins and Nitrile-Butadiene Rubber by Headspace-Capillary Gas Chromatography (HS-CGC)
• Effective Date: 01-Oct-2023
• 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 D883-22 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2022
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E456-13a(2022) - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022

Overview

ASTM D5508-23 provides a standard test method for the determination of residual acrylonitrile (RAN) monomer in styrene-acrylonitrile (SAN) copolymer resins, nitrile-butadiene rubber (NBR), and acrylonitrile-butadiene-styrene (ABS) resins. This method utilizes headspace-capillary gas chromatography (HS-CGC) to accurately identify and quantify trace amounts of acrylonitrile, which is a critical parameter for material safety and performance in polymer applications. The standard ensures assessment down to detection limits of approximately 50 parts per billion (ppb), making it suitable for quality control and regulatory compliance.

Key Topics

• Scope of the Method

  • Applies to dry rubbers and resins of NBR, SAN, and ABS.
  • Excludes samples where headspace generation of acrylonitrile from interfering components, such as 3-hydroxypropionitrile in latices, may be present.

• Test Method Summary

  • Samples and standard additions are prepared in suitable solvents, sealed in headspace vials, and agitated before thermal equilibration.
  • The headspace gas is analyzed by gas chromatography using a nitrogen-specific detector, providing the sensitivity required for low-level RAN detection.

• Safety and Environmental Considerations

  • Acrylonitrile is a regulated carcinogen; the standard emphasizes strict adherence to health and safety precautions.
  • Proper laboratory practices and environmental controls are essential.

• Measurement and Reporting

  • Results are expressed in parts per billion (ng/g) of residual acrylonitrile.
  • Ensures consistent, reliable data suitable for internal specifications or regulatory submissions.

Applications

• Quality Assurance in Polymer Manufacturing

  • Determining residual acrylonitrile is essential for verifying the suitability of NBR, SAN, and ABS polymers in food contact, medical, and consumer product applications.
  • Supports compliance with stringent industry and regulatory limits on residual monomer content.

• Health and Environmental Risk Management

  • Accurate monitoring of residual acrylonitrile minimizes occupational exposure and consumer risk.
  • Useful for manufacturers and end-users concerned about the migration of acrylonitrile from finished goods.

• Process Optimization

  • Assists manufacturers in optimizing polymerization and purification processes by providing feedback on residual monomer levels.
  • Enables continuous improvement in product safety and performance.

Related Standards

• ASTM D883 – Terminology Relating to Plastics
  Fundamental definitions that support understanding of plastic materials described in D5508.

• ASTM E456 – Terminology Relating to Quality and Statistics
  Provides terms used in the analysis and interpretation of test results.

• ASTM E691 – Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
  Outlines statistical approaches for ensuring repeatable and reproducible test outcomes.

• ASTM E2935 – Practice for Evaluating Equivalence of Two Testing Processes
  Offers guidance for method comparison and validating alternative techniques.

This standard is developed in alignment with international principles for standardization but currently has no ISO equivalent. It is routinely referenced by plastics manufacturers, quality assurance laboratories, and regulatory bodies for assessing the safety and compliance of nitrile-based and styrenic polymers.

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Keywords: ASTM D5508, residual acrylonitrile, nitrile-butadiene rubber, styrene-acrylonitrile copolymers, headspace gas chromatography, polymer testing, ABS, SAN, NBR, monomer analysis, safety compliance, quality control.

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: D5508 − 23
Standard Test Method for
Determination of Residual Acrylonitrile Monomer in Styrene-
Acrylonitrile Copolymer Resins and Nitrile-Butadiene
Rubber by Headspace-Capillary Gas Chromatography (HS-
CGC)
This standard is issued under the fixed designation D5508; 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* E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to
1.1 This test method covers the determination of the re-
Determine the Precision of a Test Method
sidual acrylonitrile (RAN) content in nitrile-butadiene rubbers
E2935 Practice for Evaluating Equivalence of Two Testing
(NBR), styrene-acrylonitrile (SAN) copolymers, and rubber-
Processes
modified acrylonitrile-butadiene-styrene (ABS) resins.
1.2 Any components that can generate acrylonitrile in the
3. Summary of Test Method
headspace procedure will constitute an interference. The pres-
3.1 Two dispersions (in o-dichlorobenzene) are prepared
ence of 3-hydroxypropionitrile in latices limits this procedure
and sealed in headspace vials for each polymer; one vial
to dry rubbers and resins.
contains the polymer in solvent while the second vial contains
1.3 The values stated in SI units are to be regarded as
the polymer, solvent, plus a known standard addition of
standard. No other units of measurement are included in this
acrylonitrile (AN). Both vials are agitated for a specified time
standard.
under ambient conditions. After agitation, the vials are ther-
mally equilibrated in a constant-temperature bath.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2 After completion of the timed equilibration, an aliquot
responsibility of the user of this standard to establish appro-
of the heated headspace gas from each vial is injected into a
priate safety, health, and environmental practices and deter-
capillary gas-chromatographic column using an automated
mine the applicability of regulatory limitations prior to use.
injection system. The capillary column will provide the chro-
Specific precautionary statements are given in 6.3 and 6.4.
matographic resolution necessary to isolate the AN from other
volatiles potentially present. The AN response is measured
NOTE 1—There is no known ISO equivalent to this standard.
using a nitrogen-specific detector (NPD). The raw data signal
1.5 This international standard was developed in accor-
is converted to a relative RAN concentration through a
dance with internationally recognized principles on standard-
standard addition calculation.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Significance and Use
mendations issued by the World Trade Organization Technical
4.1 A measurement of the residual acrylonitrile in nitrile
Barriers to Trade (TBT) Committee.
rubbers (NBR), styrene-acrylonitrile copolymers or ABS ter-
polymers will determine the polymer’s suitability for various
2. Referenced Documents
applications.
2.1 ASTM Standards:
4.2 Under optimum conditions, the minimum level of de-
D883 Terminology Relating to Plastics
tection of RAN in NBR, SAN, or ABS terpolymers is approxi-
mately 50 ppb.
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
5. Apparatus
Current edition approved Oct. 1, 2023. Published October 2023. Originally
5.1 Gas Chromatograph, equipped with a nitrogen-
approved in 1994. Last previous edition approved in 2016 as D5508 - 16. DOI:
10.1520/D5508-23.
phosphorus specific detector, backflush valve (see Fig. 1), split
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
injector, and capable of accepting megabore (0.53 mm inside
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
diameter) fused silica capillary columns. Detector make-up gas
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. is required.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5508 − 23
6.4 o-Dichlorobenzene. (Warning—o-Dichlorobenzene is
moderately toxic and should only be handled in a hood or with
proper personal protection to limit human exposure.)
NOTE 4—Each lot of o-dichlorobenzene should be analyzed under the
same instrumental conditions as the NBR samples to ensure that impuri-
ties are not present that will interfere with the acrylonitrile peak.
7. Sampling and Storage
7.1 The polymer test unit (sample) submitted for analysis
shall be supplied in the form of a 1 ⁄4 in. (45 mm) cube.
7.2 All test specimens shall be taken from the interior of the
polymer-test unit to minimize the contribution of surface
FIG. 1 Configuration of Eight-Port Valve Backflush Assembly
effects on the residual-acrylonitrile level.
7.3 Keep all polymer-test units in sealed containers. Ana-
NOTE 2—The use of a backflush configuration will provide for
lyze test-specimen solutions immediately after preparation.
operating advantages, but its use is optional. Chlorinated solvents quench
the alkali bead in a nitrogen-phosphorous detector, producing a loss of
Report any analysis delays along with the test results.
signal. While the bead (signal) will recover as the solvent evacuates the
detector, repeated quenching during a multi-run sequence may produce
8. Calibration
instabilities in the signal (and precision) over the sequence period.
8.1 Preparation of External Standard Solutions:
5.2 Automated Headspace Sampler, shall have a thermost-
8.1.1 Tare (to the nearest 0.1 mg) a 25-mL volumetric flask
atted sample tray capable of 90°C heating with constant
containing 10 mL of o-dichlorobenzene (DCB).
heating times. Automated sampling of the headspace gas in the
sample vials via a heated, constant-volume sample loop or 8.1.2 Weigh (to the nearest 0.1 mg) into the 25-mL volu-
pressure balancing sampling mechanism is required. Conduct metric flask 40 6 5 mg of AN. Dilute to the mark with DCB.
sampling to the gas chromatograph by means of a heated Label this solution as the “external-standard master solution”.
transfer line of minimum dead volume.
8.1.3 Add 1 mL of the “external-standard master solution”
to a clean 10-mL volumetric flask containing 2 mL of DCB.
5.3 Fused Silica Porous-Layer-Open-Tubular (PLOT) Cap-
Dilute to the mark with additional DCB. Label this solution as
illary Column, 30 m × 0.53 mm inside diameter.
the “external-standard working solution”.
NOTE 3—The column should be cut so as to have a 3 m section for the
8.1.4 Prepare fresh “master” and “working” solutions each
pre-column (Column 1) and a 27-m section for the analytical column
week and keep refrigerated at 4°C using Parafilm “M” to seal
(Column 2).
volumetric stoppers.
5.4 Variable Restrictor.
8.2 Generation of the External-Standard Calibration
5.5 Data-Recording Device—A strip-chart recorder, record-
Curve:
ing integrator, or computer-based data system is suitable.
NOTE 5—A new external-standard calibration curve should be gener-
5.6 Wrist-Action Shaker.
ated each week to account for any changes in the AN response due to NPD
bead fluctuations.
5.7 Analytical Balance, 0.1-mg readability.
5.8 Headspace Vials, 20-mL capacity. 8.2.1 Transfer 5 mL of DCB into seven clean headspace
vials, using a volumetric pipet.
5.9 Aluminum Crimp Caps, 20-mm diameter.
8.2.2 Add 0 (solvent blank), 1, 5, 10, 20, 60, or 100 μL of
5.10 Septa, TFE-fluorocarbon-faced silicone construction,
the “external-standard working solution”, respectively, to the
20-mm diameter.
vials.
5.11 Crimper, for 20-mm crimp caps.
8.2.3 Seal each vial immediately after addition with a
septum and crimp cap.
6. Reagents and Materials
8.2.4 Establish the instrument parameters as listed in Annex
6.1 Purity of Reagents—Chemicals of the highest purity
A1.
shall be used in all tests. Solvents shall have a minimum of
8.2.5 Obtain the peak-area values for AN in each of the
volatile impurities. Other grades shall only be used after
standards.
ascertaining that the reagent is free of interferences.
9. Procedure
6.2 Observe all health and safety recommendations for each
chemical, as prescribed by the manufacturer.
9.1 Determine the Target AN Weight for Polymer Test Units:
9.1.1 Weigh (to the nearest 0.1 mg) into a clean headspace
6.3 Acrylonitrile, 99 + %. (Warning—Acrylonitrile is an
vial 400 6 10 mg of polymer. Add 5 mL of DCB, using a
OSHA-regulated carcinogen and should not be released into
volumetric pipet. Seal vial with septum and crimp cap.
the laboratory atmosphere. All work involving acrylonitrile
should be carried out in a hood or with proper personal 9.1.2 Place the vial on a wrist-action shaker, set at maxi-
protection to minimize human exposure.) mum agitation for 16 h under ambient conditions.
D5508 − 23
9.1.3 Analyze the sample under the same instrument param- 9.3.3 Seal vials with crimper (immediately after an addi-
eters as was used to generate the external-standard calibration tion).
curve. 9.3.4 Place the vials on a wrist-action shaker, set at maxi-
mum agitation for 16 h under ambient conditions.
9.1.4 Obtain the peak-area value for AN.
9.3.5 Establish the instrument parameters as listed in Annex
9.2 Preparation of AN Standard-Addition Solution:
A1.
NOTE 6—The following steps in preparing the AN standard addition 9.3.6 Obtain the peak-area values for AN from each vial.
solution are given as an illustration only. Depending on the target weights
involved, the AN concentration of these solutions may need
...

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: D5508 − 16 D5508 − 23
Standard Test Method for
Determination of Residual Acrylonitrile Monomer in Styrene-
Acrylonitrile Copolymer Resins and Nitrile-Butadiene
Rubber by Headspace-Capillary Gas Chromatography (HS-
CGC)
This standard is issued under the fixed designation D5508; 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 covers the determination of the residual acrylonitrile (RAN) content in nitrile-butadiene rubbers (NBR),
styrene-acrylonitrile (SAN) copolymers, and rubber-modified acrylonitrile-butadiene-styrene (ABS) resins.
1.2 Any components that can generate acrylonitrile in the headspace procedure will constitute an interference. The presence of
3-hydroxypropionitrile in latices limits this procedure to dry rubbers and resins.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 6.3 and 6.4.
NOTE 1—There is no known ISO equivalent to this standard.
1.5 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
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2935 Practice for Evaluating Equivalence of Two Testing Processes
3. Summary of Test Method
3.1 Two dispersions (in o-dichlorobenzene) are prepared and sealed in headspace vials for each polymer; one vial contains the
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods and
Section D20.70.02 on Chromatography.
Current edition approved Sept. 1, 2016Oct. 1, 2023. Published September 2016October 2023. Originally approved in 1994. Last previous edition approved in 20092016
ε1
as D5508 - 94aD5508 - 16.(2009) . DOI: 10.1520/D5508-16.10.1520/D5508-23.
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.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5508 − 23
polymer in solvent while the second vial contains the polymer, solvent, plus a known standard addition of acrylonitrile (AN). Both
vials are agitated for a specified time under ambient conditions. After agitation, the vials are thermally equilibrated in a
constant-temperature bath.
3.2 After completion of the timed equilibration, an aliquot of the heated headspace gas from each vial is injected into a capillary
gas-chromatographic column using an automated injection system. The capillary column will provide the chromatographic
resolution necessary to isolate the AN from other volatiles potentially present. The AN response is measured using a
nitrogen-specific detector (NPD). The raw data signal is converted to a relative RAN concentration through a standard addition
calculation.
4. Significance and Use
4.1 A measurement of the residual acrylonitrile in nitrile rubbers (NBR), styrene-acrylonitrile copolymers or ABS terpolymers will
determine the polymer’s suitability for various applications.
4.2 Under optimum conditions, the minimum level of detection of RAN in NBR, SAN, or ABS terpolymers is approximately 50
ppb.
5. Apparatus
5.1 Gas Chromatograph, equipped with a nitrogen-phosphorus specific detector, backflush valve (see Fig. 1), split injector, and
capable of accepting megabore (0.53 mm inside diameter) fused silica capillary columns. Detector make-up gas is required.
NOTE 2—The use of a backflush configuration will provide for operating advantages, but its use is optional. Chlorinated solvents quench the alkali bead
in a nitrogen-phosphorous detector, producing a loss of signal. While the bead (signal) will recover as the solvent evacuates the detector, repeated
quenching during a multi-run sequence may produce instabilities in the signal (and precision) over the sequence period.
5.2 Automated Headspace Sampler, shall have a thermostatted sample tray capable of 90°C heating with constant heating times.
Automated sampling of the headspace gas in the sample vials via a heated, constant-volume sample loop or pressure balancing
sampling mechanism is required. Conduct sampling to the gas chromatograph by means of a heated transfer line of minimum dead
volume.
5.3 Fused Silica Porous-Layer-Open-Tubular (PLOT) Capillary Column, 30 m × 0.53 mm inside diameter.
NOTE 3—The column should be cut so as to have a 3 m section for the pre-column (Column 1) and a 27-m section for the analytical column (Column
2).
5.4 Variable Restrictor.
5.5 Data-Recording Device—A strip-chart recorder, recording integrator, or computer-based data system is suitable.
5.6 Wrist-Action Shaker.
FIG. 1 Configuration of Eight-Port Valve Backflush Assembly
D5508 − 23
5.7 Analytical Balance, 0.1-mg readability.
5.8 Headspace Vials, 20-mL capacity.
5.9 Aluminum Crimp Caps, 20-mm diameter.
5.10 Septa, TFE-fluorocarbon-faced silicone construction, 20-mm diameter.
5.11 Crimper, for 20-mm crimp caps.
6. Reagents and Materials
6.1 Purity of Reagents—Chemicals of the highest purity shall be used in all tests. Solvents shall have a minimum of volatile
impurities. Other grades shall only be used after ascertaining that the reagent is free of interferences.
6.2 Observe all health and safety recommendations for each chemical, as prescribed by the manufacturer.
6.3 Acrylonitrile, 99 + %. (Warning—Acrylonitrile is an OSHA-regulated carcinogen and should not be released into the
laboratory atmosphere. All work involving acrylonitrile should be carried out in a hood or with proper personal protection to
minimize human exposure.)
6.4 o-Dichlorobenzene. (Warning—o-Dichlorobenzene is moderately toxic and should only be handled in a hood or with proper
personal protection to limit human exposure.)
NOTE 4—Each lot of o-dichlorobenzene should be analyzed under the same instrumental conditions as the NBR samples to ensure that impurities are not
present that will interfere with the acrylonitrile peak.
7. Sampling and Storage
7.1 The polymer test unit (sample) submitted for analysis shall be supplied in the form of a 1 ⁄4 in. (45 mm) cube.
7.2 All test specimens shall be taken from the interior of the polymer-test unit to minimize the contribution of surface effects on
the residual-acrylonitrile level.
7.3 Keep all polymer-test units in sealed containers. Analyze test-specimen solutions immediately after preparation. Report any
analysis delays along with the test results.
8. Calibration
8.1 Preparation of External Standard Solutions:
8.1.1 Tare (to the nearest 0.1 mg) a 25-mL volumetric flask containing 10 mL of o-dichlorobenzene (DCB).
8.1.2 Weigh (to the nearest 0.1 mg) into the 25-mL volumetric flask 40 6 5 mg of AN. Dilute to the mark with DCB. Label this
solution as the “external-standard master solution”.
8.1.3 Add 1 mL of the “external-standard master solution” to a clean 10-mL volumetric flask containing 2 mL of DCB. Dilute to
the mark with additional DCB. Label this solution as the “external-standard working solution”.
8.1.4 Prepare fresh “master” and “working” solutions each week and keep refrigerated at 4°C using Parafilm “M” to seal
volumetric stoppers.
8.2 Generation of the External-Standard Calibration Curve:
D5508 − 23
NOTE 5—A new external-standard calibration curve should be generated each week to account for any changes in the AN response due to NPD bead
fluctuations.
8.2.1 Transfer 5 mL of DCB into seven clean headspace vials, using a volumetric pipet.
8.2.2 Add 0 (solvent blank), 1, 5, 10, 20, 60, or 100 μL of the “external-standard working solution”, respectively, to the vials.
8.2.3 Seal each vial immediately after addition with a septum and crimp cap.
8.2.4 Establish the instrument parameters as listed in Annex A1.
8.2.5 Obtain the peak-area values for AN in each of the standards.
9. Procedure
9.1 Determine the Target AN Weight for Polymer Test Units:
9.1.1 Weigh (to the nearest 0.1 mg) into a clean headspace vial 400 6 10 mg of polymer. Add 5 mL of DCB, using a volumetric
pipet. Seal vial with septum and crimp cap.
9.1.2 Place the vial on a wrist-action shaker, set at maximum agitation for 16 h under ambient conditions.
9.1.3 Analyze the sample under the same instrument parameters as was used to generate the external-standard calibration curve.
9.1.4 Obtain the peak-area value for AN.
9.2 Preparation of AN Standard-Addition Solution:
NOTE 6—The following steps in preparing the AN standard addition solution are given as an illustration only. Depending on the target weights involved,
the AN concentration of these solutions may need to be adjusted.
9.2.1 Tare (to the nearest 0.1 mg) a 25-mL volumetric flask containing 10 mL of DCB.
9.2.2 Weigh (to the nearest 0.1 mg) into the 25-mL volumetric flask 165 6 10 mg of AN. Dilute to the mark with DCB. Label
this solution as the “AN master solution”.
9.2.3 Add 50 μL of the “AN master solution” to a clean 10-mL volumetric flask containing 2 mL of DCB. Dilute to the mark with
DCB. Label this solution as the “AN working solution”. This solution has an AN concentration of 33 ng/μL.
9.2.4 Prepare fresh “master” and “working” solutions weekly or as needed for varying target levels. Keep refrigerated at 4°C using
Parafilm “M” to seal volumetric stoppers.
9.3
...