ASTM E1600-23

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: E1600 − 15 E1600 − 23
Standard Test Methods for
Determination of Gold in Cyanide Solutions
This standard is issued under the fixed designation E1600; 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 These test methods cover the determination of gold in ore processing cyanide solutions within the following ranges:
Application Range,
Method
μg/mL
Inductively Coupled Plasma Mass Spectrometry 0.001 to 0.500
Flame Atomic Absorption Spectrometry 0.300 to 10.0
NOTE 1—The lower limit for the Inductively Coupled Plasma Mass Spectrometry Method, 0.001 μg/mL, was set following the guidance of Practice
E1601. The reproducibility Index, R, was calculated using the total standard deviation for the lowest concentration Youden pair solution.
1.1.1 These test methods may also be applied to cyanide leach solutions from metallurgical evaluation procedures.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 The test methods appear in the following order:
Method Sections
Flame Atomic Absorption Spectrometry 9 – 16
Inductively Coupled Plasma Mass Spectrometry 17 – 24
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 precautions are given in 11.1, 11.1.1, 11.5, and 12.2.
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:
D1193 Specification for Reagent Water
D1293 Test Methods for pH of Water
These test methods are under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and are the direct responsibility
of Subcommittee E01.02 on Ores, Concentrates, and Related Metallurgical Materials.
Current edition approved April 1, 2015April 15, 2023. Published May 2015April 2023. Originally approved in 1994. Last previous edition approved in 20132015 as
E1600 – 13.E1600 – 15. DOI: 10.1520/E1600-15.10.1520/E1600-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1600 − 23
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D5673 Test Method for Elements in Water by Inductively Coupled Plasma—Mass Spectrometry
D6888 Test Method for Available Cyanides 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
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E173 Practice for Conducting Interlaboratory Studies of Methods for Chemical Analysis of Metals (Withdrawn 1997)
E882 Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
E1060 Practice for Interlaboratory Testing of Spectrochemical Methods of Analysis (Withdrawn 1997)
E1601 Practice for Conducting an Interlaboratory Study to Evaluate the Performance of an Analytical Method
3. Terminology
3.1 Definitions—For definitions of terms used in these test methods, refer to Terminology E135.
4. Significance and Use
4.1 In primary metallurgical processes for gold bearing ores, gold is extracted with an alkaline cyanide solution. Metallurgical
accounting, process control, and ore evaluation procedures depend on accurate, precise, and prompt measurements of the gold
concentrations.levels.
4.2 These test methods are comparative referee methods for compliance with compositional specifications for metal concentra-
tionamounts or to monitor processes. It is assumed that all who use these methods will be trained analystsusers capable of
performing common laboratory procedures skillfully and safely. It is expected that work will be performed in a properly equipped
laboratory under appropriate quality control practices such as those described in Guide E882, and that proper waste disposal
procedures will be followed.
5. Hazards
5.1 For precautions to be observed in these methods, refer to Practice E50.
5.2 Hydrogen cyanide and alkali cyanide are very toxic substances. Use an efficient fume hood. Cyanide must be disposed of with
care, avoiding contact with acid that releases hydrogen cyanide gas. Oxidation of cyanide with chlorine or hypochlorite must be
carried out conducted at high pH (greater than 11) to prevent generation of toxic cyanogen chloride gas.
5.3 See specific warnings in 11.1.1, 11.5, and 12.2.
6. Sampling and Sample Preparation
6.1 Collect, store, and dispose of the sample in accordance with Practices E50.
6.2 Preservation—Determine the pH of the solution immediately after sampling in accordance with Test Method D1293. If the pH
of the sample is less than 10, adjust the pH with small additions of solid sodium hydroxide, NaOH, followed by mixing, until the
pH is greater than 10.
6.3 Samples may be preserved toat pH 11 or higher if they are also being tested for free and weak acid dissociable cyanide in
accordance with Test Methods D6888 or D7237.
6.4 Test Solutions—Filter two 50-mL portions of preserved sample solution through a coarse-porosity filter paper.
The last approved version of this historical standard is referenced on www.astm.org.
E1600 − 23
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to
Type I or II of Specification D1193. Type III or IV may be used if they effect no measurable change in the blank or sample.
FLAME ATOMIC ABSORPTION SPECTROMETRY
8. Summary of Test Method
8.1 The sample solution is collected and preserved with sodium hydroxide, NaOH, if necessary, by careful adjustment of pH. The
test solution is filtered and gold content is determined by flame atomic absorption spectrometry.
9. Interferences
9.1 Elements normally found in ore processing cyanide solutions do not interfere. Use of instrumental background correction is
required to compensate for nonspecific absorption interferences in the flame.
NOTE 2—Alkaline soluble arsenic can cause low bias on Au by Flame AA.AAS. Sample Dilution, matrix spikes, or Method of Standard Additions may
be needed.
10. Apparatus
10.1 Flame Atomic Absorption Spectrometer, equipped with background correction and capable of measuring gold at the 242.8-nm
wavelength using an air and acetylene flame over a linear range from 0.30.3 μg μg/mL to 10.0⁄mL to 10.0 μg μg/mL ⁄mL gold.
11. Reagents and Materials
11.1 Gold Calibration Solutions (0.5, 1.0, 2.0, 5.0, 10.0) μg/mL—In a fume hood, pipette 10 mL of Gold Standard Solution A
(11.2) into a 1-L volumetric flask containing 100 mL of Sodium Cyanide-Sodium Hydroxide Solution (11.5). Dilute to volume and
mix (10 μg/mL).
11.1.1 Pipette (5, 10, 20, and 50) mL of the 10 μg/mL gold calibration solution into each of four 100-mL volumetric flasks,
respectively. respectively to make calibration solutions of (0.5, 1.0, 2.0, and 5.0) μg ⁄mL. Add 10 mL of Sodium Cyanide-Sodium
Hydroxide Solution (11.5), dilute to volume, and mix.
WARNING—Reaction of acid or chlorine and cyanide solutions releases toxic hydrogen cyanide or cyanogen chloride gases.
Prepare in a fume hood.
11.2 Gold Standard Solution A (1 mL – 1.0 μg Au)—Weigh 1.000 g of gold metal (99.99 % minimum purity) and transfer to a 1-L
beaker in a fume hood. Add 200 mL of water, 80 mL of HCl, and 50 mL of HNO (1 + 1). Boil gently to expel NO fumes, cool,
3 x
transfer to a 1-L volumetric flask, dilute to volume, and mix.
11.2.1 A certified reference solution solution, made by an accredited ISO 17034 producer, meeting these specifications may also
be used.
NOTE 3—Commercially prepared Gold Cyanide reference solutions should beare best preserved in NaCN.
Reagent Chemical, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc.,Pharmacopeial
Convention, Inc. (USPC), Rockville, MD.
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11.3 Reference Solution—Dilute 100 mL of Sodium Cyanide-Sodium Hydroxide Solution (11.5), to 1 L with water.
11.4 Sodium Cyanide.
11.5 Sodium Cyanide–Sodium Hydroxide Solution—Dissolve 10 g of sodium hydroxide, NaOH, then 10 g of sodium cyanide in
1 L of water.
WARNING —The preparation, storage, use, and disposal of sodium cyanide solutions requirerequires special care and attention.
Avoid any possibility of inhalation, ingestion, or skin contact with the compound, its solution, or its vapors. Work only in a
well-ventilated hood.
11.6 Sodium Hydroxide.
12. Preparation of Apparatus
12.1 Follow the instrument manufacturer’s instructions to adjust the instrument for gold at 242.8 nm. Warm up Stabilize the
instrument with background correction applied in accordance with the manufacturer’s instructions. With the gold hollow cathode
lamp in position, energized and stabilized, adjust the wavelength to maximize the energy response of the 242.8-nm line.
Lightwavelength. Ignite the burner, allow it to reach thermal equilibrium, and adjust the instrument to zero while aspirating water.
12.2 The use of an air-acetylene, lean, blue flame and caustic stabilized drain bottle is required.
WARNING—Reaction of acid and cyanide solutions in the burner chamber drain bottle may release toxic hydrogen cyanide
gas. Add an excess of sodium hydroxide NaOH to the drain bottle to maintain the pH above eleven.
12.3 Determine if the instrument precision is acceptable as follows:
12.3.1 Calibrate the instrument in absorbance, in accordance with the manufacturer’s instructions in absorbance. instructions. Set
the absorbance to zero while aspirating the reference solution.
12.3.2 Aspirate the calibration solutions in order of increasing concentration, and select a calibration solution in the absorbance
range from 0.2 absorbance units (AU) to 0.4 AU.
12.3.3 Alternate readings on the selected calibration solution and reference solution, and calculate the standard deviation of the
readings on the selected calibration solution using accepted statistical methods. Measure the standard deviation in this way at
increased measurement integration times until a relatively constant value is achieved.
12.3.4 If the standard deviation under these conditions is greater than 1 % of the average absorbance, determine the cause of the
variability (for example, deposits in the burner or clogged capillary), and take corrective action.
12.3.5 If the minimum requirements are not met, do not use the instrument with this test method until the required stability is
obtained.
12.3.6 Collect all instrumental measurements for the test method using the instrumental settings which gave the optimum precision
of measurement on the selected calibration solution.
12.4 Linearity of Instrument Response—Determine if the instrument response is acceptable as follows:
12.4.1 Record absorbance measurements for each of the calibration solutions and the reference solution, prior to determining-
measuring samples.
12.4.2 Adequate instrument response is obtained if the difference between the 5-μg/mL calibration solution is sufficient to permit
estimation of ⁄50 of the difference between them absorbance measurements (0.1 μg/mL).
12.4.3 Adequate linearity is confirmed if the slope of the calibration curve between the 5 μg/mL and 10 μg/mL calibration solutions
is at least 90 % of the slope between the reference solution and the 0.5-μg/mL calibration solution.
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13. Calibration
13.1 Calibrate the instrument in absorbance or gold concentration, in accordance with the manufacturer’s instructions in
absorbance or gold concentration.instructions.
14. Procedure
14.1 High-Precision Method:
14.1.1 Adjust the instrument to zero with the reference solution and measure the test sample solution to determine its place in the
order of increasing concentration of the calibration solutions.
14.1.2 Aspirate the test solution and the closely bracketing calibration solutions in order of increasing absorbance or concentration
without intervening water aspirations. Repeat three times and calculate the average absorbance or concentration value for each of
the three solutions.
14.2 Linear Curve Method:
14.2.1 Record the reference solution and calibration solution readings before and after each test sample solution, selecting a
different calibration solution after each test solution.
14.2.2 Continue recording measurements until at least three readings have been recorded for all test sample solutions and at least
one reading has been recorded for each calibration solution. Calculate the average reading for each of the solutions.
15. Calculation
15.1 High-Precision Method—The gold concentration of the test solution is calculated as follows:
A C 2 C
~ !
t h 1
C 5 (1)
t
~A 2 A !
h 1
where:
C = concentration of gold in the test solution, μg/mL,
t
C = concentration of gold in the higher calibration solution, μg/mL,
h
C = concentration of gold in the lower calibration solution, μg/mL,
A = average absorbance or concentration reading of the test solution,
t
A = average absorbance or concentration reading of the higher calibration solution, and
h
A = average absorbance or concentration of the lower calibration solution.
15.2 Linear Curve Method—Calculate the gold concentration of each test sample solution in micrograms per millilitre μg/mL
using the graphical method, by simple linear regression, or by an equivalent computer method.
15.3 Average the results of the duplicate test sample solutions and round the results to the nearest 0.1 μg/mL in accordance with
Practice E29, unless an alternative rounding method is specified by the customer or applicable material specification.
16. Precision and Bias
16.1 Precision—An interlaboratory study was undertakenconducted to test the precision of this test method in accordance with
Practice E1060 on six solutions in eight laboratories. The results from the study are summarized in Table 1. Since as few as three
laboratories returned results for some of the materials, Practice E173 was used to estimate the precision. The base data and statistics
are documented.
NOTE 4—Solutions 1 through 6 were analyzed by more laboratories than Solutions 7 through 12.
NOTE 5—The reproducibility, R2, of Practice E173 corresponds to the reproducibility index, R, of Practice E1601 and the repeatability, R1, of Practice
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report: RR:E01-1013.
E1600 − 23
TABLE 1 Gold in Cyanide Solutions—Statistical Information
R1 (Practice R2 (Practice
Solutions Mean, Au, μg/mL E173), Au, E173), Au,
μg/mL μg/mL
1, 4 2.19 0.10 0.18
2, 5 0.19 0.05 0.21
3, 6 0.96 0.02 0.05
7, 10 4.87 0.17 0.22
8, 11 5.97 0.27 0.69
9, 12 10.7 0.15 1.28
E173 corresponds to the repeatability index, r, of Practice E1601.
16.1.1 Repeatability—The repeatability standard deviation (s ) ranged from 0.01 μg/mL to 0.12 μg/mL gold over the range of the
w
materials tested. The R1 value in Table 1 for each of the materials tested indicates the maximum difference expected between
results in a single laboratory at 95 % confidence.
16.1.2 Reproducibility—The reproducibility standard deviation (s ) ranged from 0.01 μg/mL to 0.15 μg/mL gold over the range
sr
of the materials tested. The R2 value in Table 1 for each of the materials tested indicates the maximum difference expected between
results in different laboratories at 95 % confidence.
16.2 Bias—No information on the bias of this test method is known, because at the time of the interlaboratory study suitable
reference materials were not available The user of this method is encouraged to employ accepted reference materials, if available,
to determine the presence or absence of bias.
INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY
17. Summary of Test Method
17.1 This test method describes the determination of trace gold concentrations by inductively coupled plasma—mass spectrometry
(ICP-MS) based on Method D5673. Sample material in solution is introduced by pneumatic nebulization into a radiofrequency
plasma where energy transfer processes cause desolvation, atomization, and ionization. The ions are extracted from the plasma
through a differentially pumped vacuum interface and separated on the basis of their mass-to-charge ratio by a quadrupole mass
spectrometer. The ions transmitted through the quadrupole are detected by a continuous dynode electron multiplier assembly and
the ion information processed by a data handling system. Interferences relating to the technique must be recognized and corrected
forcorrections applied (see Section 18 on interferences). Such corrections must include compensation for isobaric elemental
interferences and interferences from polyatomic ions derived from the plasma gas, reagents, or sample matrix. Instrumental drift
as well as and suppressions or enhancements of instrument response caused by the sample matrix must be corrected for by the use
of internal standardization.
18. Interferences
18.1 Several types of interference effects may contribute t
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