ISO 20260:2019
(Main)Magnesium and magnesium alloys — Determination of mercury
Magnesium and magnesium alloys — Determination of mercury
This document specifies the methods for the determination of mercury in magnesium and magnesium alloys by inductively coupled plasma (ICP) atomic mass spectrometric analysis and by atomic absorption spectrometric analysis.
Magnésium et alliages de magnésium — Dosage du mercure
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 20260
First edition
2019-07
Magnesium and magnesium alloys —
Determination of mercury
Magnésium et alliages de magnésium — Dosage du mercure
Reference number
ISO 20260:2019(E)
©
ISO 2019
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ISO 20260:2019(E)
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ISO 20260:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification of methods for determination . 1
5 Sampling, storing and weighing of analytical samples . 2
5.1 Sampling . 2
5.2 Storing of analytical sample . 2
5.3 Weighing of the analytical sample . 2
6 Apparatus . 2
7 ICP mass spectrometric analysis (Method A) . 3
7.1 Summary . 3
7.2 Reagents. 3
7.3 Amount of sample to be weighed out . 4
7.4 Operation . 4
7.5 Blank test . 4
7.6 Preparation of the working curve . 5
7.7 Calculation . 5
7.8 Reporting analytical data . 5
8 Atomic absorption spectrometric analysis (Method B) . 5
8.1 Summary . 5
8.2 Reagents. 6
8.3 Amount of sample to be weighed out . 6
8.4 Apparatus and implements . 7
8.5 Operation . 8
8.5.1 Preparation of the sample solution . 8
8.5.2 Measurement of absorbance . 9
8.6 Operation blank test . 9
8.7 Preparation of the working curve . 9
8.8 Calculation . 9
8.9 Reporting analytical data .10
Bibliography .11
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ISO 20260:2019(E)
Foreword
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This document was prepared by Technical Committee ISO/TC 79, Light metals and their alloys,
Subcommittee SC 5, Magnesium and alloys of cast or wrought magnesium.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
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ISO 20260:2019(E)
Introduction
Magnesium is the lightest of all the common metals and has been prepared for industry use as metal
ingots and alloys since these have the best strength-to-weight ratio of any of the commonly used
structural alloys. Chemical compositions of magnesium and its alloys are widely standardized from
major to trace quantities. Mercury has generally been a non-analysing element to monitor because it
seems to be volatilized on heating due to its low boiling point. Thus, mercury has not been prescribed
solely in standards, but has been included as impurities in standards. ISO 8287 for unalloyed magnesium
specifies that the sum of hazardous elements, including mercury, in all materials should be less than
0,01 % mass fraction. ISO 16220 for magnesium alloy ingots and casting denotes the impure elements
should not be less than 0,01 % separately.
However, there exists no standardized analytical methods for determination of mercury in magnesium
and magnesium alloys. Moreover, a new global mercury treaty called the Minamata Convention
that came into effect in 2020, which regulates and controls mercury globally, has encouraged the
development of the analysis of mercury on some trading materials and products.
This document specifies the methods for determination of trace levels of mercury in magnesium and
magnesium alloys.
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INTERNATIONAL STANDARD ISO 20260:2019(E)
Magnesium and magnesium alloys — Determination of
mercury
1 Scope
This document specifies the methods for the determination of mercury in magnesium and magnesium
alloys by inductively coupled plasma (ICP) atomic mass spectrometric analysis and by atomic absorption
spectrometric analysis.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 384, Laboratory glass and plastics ware — Principles of design and construction of volumetric
instruments
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4787, Laboratory glassware — Volumetric instruments — Methods for testing of capacity and for use
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Classification of methods for determination
The method for the determination of tin shall be in accordance with any one of the following methods.
a) ICP mass spectrometric analysis (Method A).
This method is applicable to magnesium and magnesium alloy of 0,000 01 % (mass fraction) or
over up to and including 0,01 % (mass fraction) in mercury content.
b) Atomic absorption spectrometric analysis (Method B).
This method is applicable to magnesium and magnesium alloy of 0,000 02 % (mass fraction) or
over up to and including 0,001 % (mass fraction) in mercury content.
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ISO 20260:2019(E)
5 Sampling, storing and weighing of analytical samples
5.1 Sampling
Sampling shall be carried out as follows.
a) When the chips are sampled from a casting sample (A) or a product sample (B), select the sampling
position so as to represent the quality of the sample, and penetrate the sample by boring at right
angles to its surface. In the case of a sample with a thickness not penetrable from one direction,
another suitable method (e.g. boring from two directions) shall be used.
b) Prior to boring for chipping, clean the drill (which is not more than 10 mm in diameter) using
ethanol. Remove the adhered matters on the surface of the sampling position, and then carry out
the boring, without using any sort of oils or lubricant and with just enough force to drill without
oxidizing the sample chips. At this time, adjust the pressure exerted or the revolution frequency of
the drill so that no excessive heat is generated. Do not attempt to cool off or stop the temperature
from rising by pouring water or another liquid over the sample.
The use of cutting tools other than a drill, such as a lathe, is permissible.
c) Collect all of the sample chips (which shall be no larger than 10 mm), and remove iron powder, etc.,
using a strong magnet. Then, mix the chips together thoroughly to create the analytical sample and
leave them in a desiccator to cool to room temperature.
d) If the sampling from specimens such as thin sheets, pipes, etc., cannot be in accordance with the
specifications given in a) to c), the sampling method shall be as agreed by the purchaser and the
supplier.
5.2 Storing of analytical sample
The analytical sample shall be stored as follows.
a) Store the sample in a glass container with a lid sealed hermetically to prevent contamination.
b) If there is the possibility that substances (e.g. oil) have adhered on the surface, clean the analytical
sample using a product (e.g. ethanol, acetone) and dry it before using.
5.3 Weighing of the analytical sample
The analytical sample shall be weighed as follows.
a) Mix the sample thoroughly so that any portion weighed out represents the average composition.
b) Weigh out 0,1 g (method A) or 0,5 g (method B) of the sample to a digit of 1 mg by using an analytical
balance described in 6.3.
6 Apparatus
Use normal laboratory apparatus and, in particular, the following.
6.1 Volumetric glassware, of Class A in accordance with ISO 384, ISO 648 and ISO 1042, and used in
accordance with ISO 4787.
6.2 Analytical balance, sensitive to 0,1 mg.
6.3 ICP mass spectrometer, to measure the ion intensities of mercury with separate masses from the
inductively coupled plasma.
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ISO 20260:2019(E)
6.4 Atomic absorption spectrometer, to measure the light absorption of specific wavelength arising
from mercury in the quartz cell.
7 ICP mass spectrometric analysis (Method A)
7.1 Summary
The aqueous solution including the chipped magnesium sample is added with solution of permanganate
ion prior to dissolution. The solution is then decomposed with nitric acid, thus supressing volatilization
of mercury in the sample. Precipitates of manganese(IV) oxide generated during decomposition are
reduced with hydroxyl ammonium chloride. The prepared solution is sprayed into the argon plasma of
the ICP mass spectrometer and the ion intensities of mercury are measured.
7.2 Reagents
During the analysis, use only reagents of recognized analytical grade and water that conforms to
grade 1 or 2 of ISO 3696.
7.2.1 Hydrochloric acid, 1+1.
Dilute hydrochloric acid [35 % to 37 % (mass fraction)] of analytical grade twice with water.
7.2.2 Nitric ac
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