GB/T 15072.6-2025 Methods for chemical analysis of precious metal alloys—Part 6: Determination of iridium content English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS 97.120.99
CCS H 57
National Standard of the People's Republic of China
GB/T 15072.6-2025
Replaces GB/T 15072.6-2008
Methods for chemical analysis of precious metal alloys - Part 6: Determination of iridium content
Issue date: 2025-08-29 Implementation date: 2026-03-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents and Materials
6 Instruments and Equipment
7 Sample
8 Procedure
9 Data Processing
Methods for chemical analysis of precious metal alloys - Part 6: Determination of iridium content
Warning—Personnel using this document shall have practical experience in a standard laboratory setting. This document does not address all potential safety issues. The user is responsible for implementing appropriate safety and health measures and ensuring compliance with national regulatory requirements.
1 Scope
This document specifies the ferrous sulfate potentiometric titration method for the determination of iridium content in precious metal alloys.
This method is applicable to the determination of iridium in precious metal alloys, with a measuring range (mass fraction) of 5.00% to 30.00%.
2 Normative References
The following documents, through normative citations in this text, constitute essential provisions. For dated references, only the edition cited applies; for undated references, the latest version (including amendments) applies.
GB/T 8170 Rules for rounding off numbers and expression of limiting values
3 Terms and Definitions
No terms or definitions require definition in this document.
4 Principle
The test sample is placed in a polytetrafluoroethylene digestion vessel, dissolved with hydrochloric acid and hydrogen peroxide in an oven. Ruthenium is oxidized and separated from the matrix using sodium bromate, while palladium is reduced and separated using copper powder. In a hydrochloric acid and sulfuric acid medium, ferrous sulfate standard titrant is used to reduce Ir(IV) to Ir(III), with the endpoint determined by potentiometric titration to measure iridium content.
5 Reagents and Materials
Unless otherwise specified, only analytical-grade reagents and distilled or deionized water (or equivalent purity) are used.
5.1 Potassium chlorate (GR)
5.2 Copper powder: Prepared by reducing zinc powder with copper sulfate solution (197 g/L), followed by washing with hydrochloric acid.
5.3 Hydrochloric acid (ρ=1.19 g/mL)
5.4 Hydrogen peroxide (30%)
5.5 Sulfuric acid (ρ=1.84 g/mL)
5.6 Sulfuric acid solution (4+96)
5.7 Sodium chloride saturated solution
5.8 Sodium chlorate solution (100 g/L)
5.9 Sodium bromate solution (100 g/L)
5.10 Ferrous sulfate standard titrant (c(FeSO₄·7H₂O) ≈ 0.0011 mol/L): Prepared by dissolving 0.318 g FeSO₄ in 1 L sulfuric acid (5.6) and standardized using iridium standard solution.
5.11 Iridium standard solution (0.5 mg Ir/mL): Prepared by dissolving iridium powder (≥99.99%) in hydrochloric acid with potassium chlorate.
6 Instruments and Equipment
6.1 Balance (sensitivity 0.01 mg)
6.2 Titration setup (automatic potentiometric titrator, see Appendix A for parameters)
6.3 Polytetrafluoroethylene digestion vessel (30 mL, wall thickness 25±2 mm)
6.4 Oven (≤300 °C)
6.5 Magnetic stirrer
6.6 Gas blowing apparatus (as shown in Figure 1)
Figure 1 Schematic Diagram of Gas Blowing Apparatus
7 Sample
The sample is processed into shreds with a thickness ≤ 0.2 mm and length/width ≤ 2.0 mm. Soaked in ** glacial acetic acid for 10 min**, rinsed with anhydrous ethanol, dried, and homogenized.
8 Procedure
8.1 Test Portion
Weigh 0.1 g of the sample (Section 7) to ±0.00001 g.
8.2 Duplicate Test
Conduct two parallel tests and report the average.
8.3 Blank Test
Perform a blank test alongside the sample.
8.4 Determination
8.4.1 Sample Dissolution
Place the test portion (8.1) in a PTFE digestion vessel (6.3).
Add 20 mL HCl (5.3) and 5 mL H₂O₂ (5.4).
Seal and heat at 150 ± 5°C for 36 h.
After cooling, transfer to:
50 mL volumetric flask (if Ir ≤ 10%).
100 mL volumetric flask (if Ir > 10%).
Dilute to volume with water and mix well.
8.4.2 Test Solution Treatment
8.4.2.1 Test Solution without Ru/Pd
Pipette 20 mL of test solution (8.4.1) into a 100 mL tall-form beaker.
Add 5 mL HCl (5.3), 5 mL H₂SO₄ (5.5), and 0.5 mL saturated NaCl (5.7).
8.4.2.2 Test Solution with Ru
Pipette 20 mL into a 100 mL beaker, add 0.5 mL saturated NaCl (5.7), and evaporate to wet salt.
Standard
GB/T 15072.6-2025 Methods for chemical analysis of precious metal alloys—Part 6: Determination of iridium content (English Version)
Standard No.
GB/T 15072.6-2025
Status
to be valid
Language
English
File Format
PDF
Word Count
9000 words
Price(USD)
270.0
Implemented on
2026-3-1
Delivery
via email in 1~3 business day
Detail of GB/T 15072.6-2025
Standard No.
GB/T 15072.6-2025
English Name
Methods for chemical analysis of precious metal alloys—Part 6: Determination of iridium content
GB/T 15072.6-2025 Methods for chemical analysis of precious metal alloys—Part 6: Determination of iridium content English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS 97.120.99
CCS H 57
National Standard of the People's Republic of China
GB/T 15072.6-2025
Replaces GB/T 15072.6-2008
Methods for chemical analysis of precious metal alloys - Part 6: Determination of iridium content
Issue date: 2025-08-29 Implementation date: 2026-03-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Reagents and Materials
6 Instruments and Equipment
7 Sample
8 Procedure
9 Data Processing
Methods for chemical analysis of precious metal alloys - Part 6: Determination of iridium content
Warning—Personnel using this document shall have practical experience in a standard laboratory setting. This document does not address all potential safety issues. The user is responsible for implementing appropriate safety and health measures and ensuring compliance with national regulatory requirements.
1 Scope
This document specifies the ferrous sulfate potentiometric titration method for the determination of iridium content in precious metal alloys.
This method is applicable to the determination of iridium in precious metal alloys, with a measuring range (mass fraction) of 5.00% to 30.00%.
2 Normative References
The following documents, through normative citations in this text, constitute essential provisions. For dated references, only the edition cited applies; for undated references, the latest version (including amendments) applies.
GB/T 8170 Rules for rounding off numbers and expression of limiting values
3 Terms and Definitions
No terms or definitions require definition in this document.
4 Principle
The test sample is placed in a polytetrafluoroethylene digestion vessel, dissolved with hydrochloric acid and hydrogen peroxide in an oven. Ruthenium is oxidized and separated from the matrix using sodium bromate, while palladium is reduced and separated using copper powder. In a hydrochloric acid and sulfuric acid medium, ferrous sulfate standard titrant is used to reduce Ir(IV) to Ir(III), with the endpoint determined by potentiometric titration to measure iridium content.
5 Reagents and Materials
Unless otherwise specified, only analytical-grade reagents and distilled or deionized water (or equivalent purity) are used.
5.1 Potassium chlorate (GR)
5.2 Copper powder: Prepared by reducing zinc powder with copper sulfate solution (197 g/L), followed by washing with hydrochloric acid.
5.3 Hydrochloric acid (ρ=1.19 g/mL)
5.4 Hydrogen peroxide (30%)
5.5 Sulfuric acid (ρ=1.84 g/mL)
5.6 Sulfuric acid solution (4+96)
5.7 Sodium chloride saturated solution
5.8 Sodium chlorate solution (100 g/L)
5.9 Sodium bromate solution (100 g/L)
5.10 Ferrous sulfate standard titrant (c(FeSO₄·7H₂O) ≈ 0.0011 mol/L): Prepared by dissolving 0.318 g FeSO₄ in 1 L sulfuric acid (5.6) and standardized using iridium standard solution.
5.11 Iridium standard solution (0.5 mg Ir/mL): Prepared by dissolving iridium powder (≥99.99%) in hydrochloric acid with potassium chlorate.
6 Instruments and Equipment
6.1 Balance (sensitivity 0.01 mg)
6.2 Titration setup (automatic potentiometric titrator, see Appendix A for parameters)
6.3 Polytetrafluoroethylene digestion vessel (30 mL, wall thickness 25±2 mm)
6.4 Oven (≤300 °C)
6.5 Magnetic stirrer
6.6 Gas blowing apparatus (as shown in Figure 1)
Figure 1 Schematic Diagram of Gas Blowing Apparatus
7 Sample
The sample is processed into shreds with a thickness ≤ 0.2 mm and length/width ≤ 2.0 mm. Soaked in ** glacial acetic acid for 10 min**, rinsed with anhydrous ethanol, dried, and homogenized.
8 Procedure
8.1 Test Portion
Weigh 0.1 g of the sample (Section 7) to ±0.00001 g.
8.2 Duplicate Test
Conduct two parallel tests and report the average.
8.3 Blank Test
Perform a blank test alongside the sample.
8.4 Determination
8.4.1 Sample Dissolution
Place the test portion (8.1) in a PTFE digestion vessel (6.3).
Add 20 mL HCl (5.3) and 5 mL H₂O₂ (5.4).
Seal and heat at 150 ± 5°C for 36 h.
After cooling, transfer to:
50 mL volumetric flask (if Ir ≤ 10%).
100 mL volumetric flask (if Ir > 10%).
Dilute to volume with water and mix well.
8.4.2 Test Solution Treatment
8.4.2.1 Test Solution without Ru/Pd
Pipette 20 mL of test solution (8.4.1) into a 100 mL tall-form beaker.
Add 5 mL HCl (5.3), 5 mL H₂SO₄ (5.5), and 0.5 mL saturated NaCl (5.7).
8.4.2.2 Test Solution with Ru
Pipette 20 mL into a 100 mL beaker, add 0.5 mL saturated NaCl (5.7), and evaporate to wet salt.
