ASTM D6696-05e1

Standard Guide for Understanding Cyanide Species

SIGNIFICANCE AND USE
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 from which to discuss and reference different cyanide chemical species and groups of cyanide compounds.
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 standard terminology used for the classification of the 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.

General Information

• Status: Historical
• Publication Date: 30-Jun-2005
• ICS: 01.040.79 - Wood technology (Vocabularies)
• ICS: 71.080.99 - Other organic chemicals
• Technical Committee: D19 - Water
• Drafting Committee: D19.06 - Methods for Analysis for Organic Substances in Water

Relations

• Replaces: ASTM D6696-05 - Standard Guide for Understanding Cyanide Species
• Effective Date: 01-Jul-2005
• Replaced By: ASTM D6696-10 - Standard Guide for Understanding Cyanide Species
• Effective Date: 01-Jun-2010
• Referred By: ASTM E800-20 - Standard Guide for Measurement of Gases Present or Generated During Fires
• Effective Date: 01-Jul-2005
• Referred By: ASTM D8273-20 - Standard Practice for Determination of Total and Available Cyanide in Solid Waste and Soil after Alkaline Extraction
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7237-18 - Standard Test Method for Free Cyanide and Aquatic Free Cyanide with Flow Injection Analysis (FIA) Utilizing Gas Diffusion Separation and Amperometric Detection
• Effective Date: 01-Jul-2005
• Referred By: ASTM D2036-09(2022) - Standard Test Methods for Cyanides in Water
• Effective Date: 01-Jul-2005
• Referred By: ASTM D6888-16 - Standard Test Method for Available Cyanides with Ligand Displacement and Flow Injection Analysis (FIA) Utilizing Gas Diffusion Separation and Amperometric Detection
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7728-18 - Standard Guide for Selection of ASTM Analytical Methods for Implementation of International Cyanide Management Code Guidance
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7511-12(2017)e1 - Standard Test Method for Total Cyanide by Segmented Flow Injection Analysis, In-Line Ultraviolet Digestion and Amperometric Detection
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7365-09a(2022) - Standard Practice for Sampling, Preservation and Mitigating Interferences in Water Samples for Analysis of Cyanide
• Effective Date: 01-Jul-2005
• Referred By: ASTM D6994-15 - Standard Test Method for Determination of Metal Cyanide Complexes in Wastewater, Surface Water, Groundwater and Drinking Water Using Anion Exchange Chromatography with UV Detection
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7284-20 - Standard Test Method for Total Cyanide in Water by Micro Distillation followed by Flow Injection Analysis with Gas Diffusion Separation and Amperometric Detection
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7295-18 - Standard Practice for Sampling Combustion Effluents and Other Stationary Sources for the Subsequent Determination of Hydrogen Cyanide
• Effective Date: 01-Jul-2005
• Referred By: ASTM D7572-15(2022) - Standard Guide for Recovery of Aqueous Cyanides by Extraction from Mine Rock and Soil
• Effective Date: 01-Jul-2005

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation:D6696–05
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
´ NOTE—Table 2 was corrected editorially in January 2006.
1. Scope 5. Cyanide Species Terms and Definitions
1.1 This guide defines standard terminology used for the 5.1 Chemistry Related Terms and Definitions:
classification of the various chemical forms of cyanide. It is 5.1.1 Cyanide Ion—The term used to describe a negatively
intended to provide a general understanding of the chemical charged ion comprised of one carbon atom and one nitrogen
-
nature of distinct cyanide species as related to chemical atom triply bonded to each other (C[N ). The cyanide ion is
analysis and environmental fate and transport. reactive and readily forms neutral compounds or anionic
complexes with most metals.
2. Referenced Documents
5.1.2 Free Cyanide—The form of cyanide that is bioavail-
2
2.1 ASTM Standards:
able and known for its toxic effect on organisms (1). Free
D1129 Terminology Relating to Water cyanide refers to the sum of molecular hydrogen cyanide
-
(HCN)andcyanideion(CN ).Hydrogencyanideisacolorless,
3. Terminology
poisonous gas having an odor of bitter almonds (mp = -13.4°C,
3.1 Definitions—Foradefinitionoftermsusedinthisguide,
bp = 25.6°C). It is readily soluble in water partitioning itself as
-
refer to Terminology D1129.
HCN or CN , or both, depending on the pH conditions
(pK = 9.36). At a pH of 7 or less in water, free cyanide is
a
4. Significance and Use
present entirely as HCN; the opposite is true at pH 11 or
4.1 This guide provides standard terminology for use in
greater. Because of its toxicity, free cyanide is regulated in
identifying and describing the different chemical forms of
environmental wastewater discharges.
cyanide. The complex nature of cyanide chemistry, existence
5.1.3 Simple Cyanide—A neutral compound comprised of
of numerous distinct chemical forms as well as the various
an alkali metal, alkaline earth metal or ammonium cation
regulatory distinctions that may be made can lead to confusion
bound to cyanide. Simple cyanides are so named because of
in technical discussions on cyanide and in the selection of
their structural simplicity and their ability to completely
appropriate methods for its analysis. This guide is intended to
dissolve and dissociate in water to produce free cyanide and a
provide clarification and a common framework of terms and
cation according to the following reaction:
definitions from which to discuss and reference different
1 2
ACN→ A 1 CN (1)
cyanide chemical species and groups of cyanide compounds.
4.2 The use of such common terminology is particularly
where:
important from an environmental perspective because certain
A = alkali metal, alkaline earth metal or ammonium cation.
forms of cyanide are considered to be toxic. Therefore, their
Examples of simple cyanides include sodium cyanide
release into the environment is regulated by federal and state
(NaCN) and potassium cyanide (KCN).
agencies. Thus a general understanding of cyanide chemistry
5.1.4 Metal Cyanide Complex—A negatively charged ionic
and species definitions is needed for proper wastewater man-
complex consisting of several cyanide ions bound to a single
agement and testing.
transition metal cation. Also referred to as “metal-complexed
cyanides,” “metal cyano-complexes” or “transition metal cya-
1
nides,” these species have the general formula:
This guide is under the jurisdiction of ASTM Committee D19 on Water and is
the direct responsibility of Subcommittee D19.06 on Organic Constituents inWater.
x2
@M~CN! # (2)
b
Current edition approved July 1, 2005. Published July 2005. Originally approved
in 2001. Last previous edition approved in 2001 as D6696 – 01. DOI: 10.1520/
where:
D6696-05E01.
2
M = transition metal cation,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM b = number of cyanide groups, and
Standards volume information, refer to the standard’s Document Summary page on
x = ionic charge of the transition metal complex.
the ASTM website.
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D6696–05
TABLE 2 Selected Strong Metal Cyanide Complexes (2, 3)
Metal cyanide complexes are represented by the following
equilibrium in aqueous solution: Cyanide Complex Stability Constant (log K at 25°C)
A,B
x2
...