ASTM D6696-16
(Guide)Standard Guide for Understanding Cyanide Species
Standard Guide for Understanding Cyanide Species
SIGNIFICANCE AND USE
4.1 This guide provides standard terminology for use in identifying and describing the different chemical forms of cyanide. The complex nature of cyanide chemistry, existence of numerous distinct chemical forms as well as the various regulatory distinctions that may be made can lead to confusion in technical discussions on cyanide and in the selection of appropriate methods for its analysis. This guide is intended to provide clarification and a common framework of terms and definitions to facilitate discussions and referencing different cyanide chemical species and groups of cyanide compounds.
4.2 The use of such common terminology is particularly important from an environmental perspective because certain forms of cyanide are considered to be toxic. Therefore, their release into the environment is regulated by federal and state agencies. Thus a general understanding of cyanide chemistry and species definitions is needed for proper wastewater management and testing.
SCOPE
1.1 This guide defines guidance based on a consensus of viewpoints for interpretation of test results to identify various chemical forms of cyanide. It is intended to provide a general understanding of the chemical nature of distinct cyanide species as related to chemical analysis and environmental fate and transport.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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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: D6696 − 16
Standard Guide for
1
Understanding Cyanide Species
This standard is issued under the fixed designation D6696; 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* appropriate methods for its analysis. This guide is intended to
provide clarification and a common framework of terms and
1.1 This guide defines guidance based on a consensus of
definitions to facilitate discussions and referencing different
viewpoints for interpretation of test results to identify various
cyanide chemical species and groups of cyanide compounds.
chemical forms of cyanide. It is intended to provide a general
understanding of the chemical nature of distinct cyanide 4.2 The use of such common terminology is particularly
species as related to chemical analysis and environmental fate important from an environmental perspective because certain
and transport. forms of cyanide are considered to be toxic. Therefore, their
release into the environment is regulated by federal and state
1.2 The values stated in SI units are to be regarded as
agencies. Thus a general understanding of cyanide chemistry
standard. No other units of measurement are included in this
and species definitions is needed for proper wastewater man-
standard.
agement and testing.
2. Referenced Documents
5. Cyanide Species Terms and Definitions
2
2.1 ASTM Standards:
5.1 Chemistry Related Terms and Definitions:
D1129 Terminology Relating to Water
5.1.1 Cyanide Ion—The term used to describe a negatively
D1426 Test Methods for Ammonia Nitrogen In Water
charged ion comprised of one carbon atom and one nitrogen
D3590 Test Methods for Total Kjeldahl Nitrogen in Water
-
atom triply bonded to each other (C≡N ). The cyanide ion is
D6888 Test Method for Available Cyanides with Ligand
reactive and readily forms neutral compounds or anionic
Displacement and Flow InjectionAnalysis (FIA) Utilizing
complexes with most metals.
Gas Diffusion Separation and Amperometric Detection
5.1.2 Free Cyanide—The form of cyanide that is bioavail-
D7237 Test Method for Free Cyanide and Aquatic Free
3
able and known for its toxic effect on organisms (1). Free
Cyanide with Flow InjectionAnalysis (FIA) Utilizing Gas
cyanide refers to the sum of molecular hydrogen cyanide
Diffusion Separation and Amperometric Detection
-
(HCN)andcyanideion(CN ).Hydrogencyanideisacolorless,
3. Terminology
poisonous gas having an odor of bitter almonds (mp = -13.4°C,
bp = 25.6°C). It is readily soluble in water existing as HCN or
3.1 Definitions—For a definition of terms used in this guide,
-
CN , or both, depending on the pH conditions (pK = 9.36).At
refer to Terminology D1129. a
a pH of 7 or less in water, free cyanide is present entirely as
4. Significance and Use
HCN; the opposite is true at pH 11 or greater. Because of its
toxicity, free cyanide is regulated in environmental wastewater
4.1 This guide provides standard terminology for use in
discharges.
identifying and describing the different chemical forms of
5.1.2.1 In Test Method D7237, sum of the free cyanide
cyanide. The complex nature of cyanide chemistry, existence
-
(HCN and CN ) and cyanide bound in the metal-cyanide
of numerous distinct chemical forms as well as the various
complexes that are easily dissociated into free cyanide under
regulatory distinctions that may be made can lead to confusion
thetestconditionsdescribedinTestMethodD7237atpH6and
in technical discussions on cyanide and in the selection of
room temperature.
5.1.3 Aquatic Free Cyanide—In Test Method D7237, free
1
This guide is under the jurisdiction of ASTM Committee D19 on Water and is
cyanidemeasuredwhenthebufferortemperatureisadjustedto
the direct responsibility of Subcommittee D19.06 on Methods for Analysis for
mimic the receiving water environment.
Organic Substances in Water.
Current edition approved April 1, 2016. Published April 2016. Originally 5.1.4 Simple Cyanide—A neutral compound comprised of
approved in 2001. Last previous edition approved in 2014 as D6696 – 14. DOI:
an alkali metal, alkaline earth metal or ammonium cation
10.1520/D6696-16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to a list of references at the end of
the ASTM website. this standard.
*A Summary of Change
...
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: D6696 − 14 D6696 − 16
Standard Guide for
1
Understanding Cyanide Species
This standard is issued under the fixed designation D6696; 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 guide defines guidance based on a consensus of viewpoints for interpretation of test results to identify various chemical
forms of cyanide. It is intended to provide a general understanding of the chemical nature of distinct cyanide species as related
to chemical analysis and environmental fate and transport.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
2. Referenced Documents
2
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D1426 Test Methods for Ammonia Nitrogen In Water
D3590 Test Methods for Total Kjeldahl Nitrogen in Water
D6888 Test Method for Available Cyanide with Ligand Displacement and Flow Injection Analysis (FIA) Utilizing Gas Diffusion
Separation and Amperometric Detection
D7237 Test Method for Free Cyanide and Aquatic Free Cyanide with Flow Injection Analysis (FIA) Utilizing Gas Diffusion
Separation and Amperometric Detection
3. Terminology
3.1 Definitions—For a definition of terms used in this guide, refer to Terminology D1129.
4. Significance and Use
4.1 This guide provides standard terminology for use in identifying and describing the different chemical forms of cyanide. The
complex nature of cyanide chemistry, existence of numerous distinct chemical forms as well as the various regulatory distinctions
that may be made can lead to confusion in technical discussions on cyanide and in the selection of appropriate methods for its
analysis. This guide is intended to provide clarification and a common framework of terms and definitions to facilitate discussions
and referencing different cyanide chemical species and groups of cyanide compounds.
4.2 The use of such common terminology is particularly important from an environmental perspective because certain forms
of cyanide are considered to be toxic. Therefore, their release into the environment is regulated by federal and state agencies. Thus
a general understanding of cyanide chemistry and species definitions is needed for proper wastewater management and testing.
5. Cyanide Species Terms and Definitions
5.1 Chemistry Related Terms and Definitions:
5.1.1 Cyanide Ion—The term used to describe a negatively charged ion comprised of one carbon atom and one nitrogen atom
-
triply bonded to each other (C≡N ). The cyanide ion is reactive and readily forms neutral compounds or anionic complexes with
most metals.
3
5.1.2 Free Cyanide—The form of cyanide that is bioavailable and known for its toxic effect on organisms (1). Free cyanide
-
refers to the sum of molecular hydrogen cyanide (HCN) and cyanide ion (CN ). Hydrogen cyanide is a colorless, poisonous gas
-
having an odor of bitter almonds (mp = -13.4°C, bp = 25.6°C). It is readily soluble in water existing as HCN or CN , or both,
1
This guide is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.06 on Methods for Analysis for Organic
Substances in Water.
Current edition approved Jan. 1, 2014April 1, 2016. Published January 2014April 2016. Originally approved in 2001. Last previous edition approved in 20102014 as
D6696 – 10.D6696 – 14. DOI: 10.1520/D6696-14.10.1520/D6696-16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The boldface numbers in parentheses refer to a list of references at the end of this standard.
*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
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D6696 − 16
depending on the pH conditions (pK = 9.36). At a pH of 7 or less in water, free cyanide is present entirely as HCN; the opposite
a
is true at pH 11 or greater. Because of its toxicity, free cyanide is regulated in environmental wastewater discharges.
-
5.1.2.1 In Test Method D7237, sum of the free cyanide (HCN and CN )
...
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