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GB/T 15072.1-2025Methods for chemical analysis of precious metal alloys — Part 1: Determination of gold content (English PDF)

贵金属合金化学分析方法第1部分：金含量的测定

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

August 29, 2025

Implementation date

March 1, 2026

Scope

GB/T 15072.1-2025 is the English-translated version of 贵金属合金化学分析方法第1部分：金含量的测定.

GB/T 15072.1-2025 describes two methods for determining the gold content of precious metal alloys: ferrous sulfate potentiometric titration, for mass fractions from 3.00 % to 99.60 %, and fire assay gravimetry, for 5.00 % to 99.60 % in samples whose total platinum group metal content is below 0.005 %.

In the titration method the chips are dissolved in nitric and hydrochloric acid (or, when platinum, rhodium or iridium are present, in hydrochloric acid and hydrogen peroxide in a closed PTFE vessel), gold is separated from the matrix by reduction with copper(I) chloride, and Au(I) is titrated to Au(0) with standardised ferrous sulfate in a sulfuric-phosphoric acid medium on an automatic potentiometric titrator.

The document specifies the reagents, the preparation and standardisation of the ferrous sulfate titrant against a gold standard solution, the apparatus, sample preparation, the calculation and the precision requirements, with the titrator operating parameters in an annex.

It is Part 1 of the GB/T 15072 series and replaces GB/T 15072.1-2008: the upper limit rises from 99.5 % to 99.60 %, the manual potentiometer gives way to an automatic titrator, a reproducibility requirement replaces the old allowable difference, and the fire assay gravimetric method is added.

Issued on 29 August 2025 and in force since 1 March 2026. Classification: ICS 77.120.99, CCS H 15. The document runs to 19 pages, delivered complete in English translation.

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Document preview — GB/T 15072.1-2025

National Standard of the People's Republic of China

ICS: 77.120.99
Classification: H 15
Replacing: GB/T 15072.1-2008

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

ForewordI
IntroductionIII
1 Scope1
2 Normative references1
3 Terms and definitions1
4 Method 1 - Ferrous sulfate potentiometric titration1
4.1 Principle1
4.2 Reagents or materials1
4.3 Apparatus2
4.4 Samples2

Foreword

This document is drafted in accordance with GB/T 1.1-2020, Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.

This document is Part 1 of GB/T 15072, Methods for chemical analysis of precious metal alloys. The following parts of GB/T 15072 have been published:

— Part 1: Determination of gold content;

— Part 2: Determination of silver content;

— Part 3: Determination of platinum content;

— Part 4: Determination of palladium content;

— Part 6: Determination of iridium content;

— Part 7: Determination of chromium and iron contents in gold alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 8: Determination of copper content in gold, palladium and silver alloys - Thiourea precipitation EDTA complexometric back titration;

— Part 9: Determination of indium content in gold alloys - EDTA complexometric back titration;

— Part 10: Determination of nickel content in gold alloys - EDTA complexometric back titration;

— Part 11: Determination of gadolinium and beryllium contents in gold alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 12: Determination of vanadium content in silver alloys - Hydrogen peroxide spectrophotometry;

— Part 13: Determination of tin, cerium and lanthanum contents in silver alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 14: Determination of aluminium and nickel contents in silver alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 15: Determination of nickel, zinc and manganese contents in gold, silver and palladium alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 16: Determination of copper and manganese contents in gold alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 17: Determination of tungsten content in platinum alloys - Tungsten trioxide gravimetric method;

— Part 18: Determination of zirconium and gallium contents in gold alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 19: Determination of vanadium and magnesium contents in silver alloys - Inductively coupled plasma atomic emission spectrometry;

— Part 20: Determination of rhodium content.

This document replaces GB/T 15072.1-2008, Methods for chemical analysis of precious metal alloys - Determination of gold content in gold, platinum and palladium alloys - Ferrous sulfate potentiometric titration. Compared with GB/T 15072.1-2008, apart from structural adjustments and editorial changes, the main technical changes are as follows:

a) the upper limit of the measurement range has been changed from 99.5 % to 99.60 % (see Clause 1; Clause 1 of the 2008 edition);

b) the titration equipment has been changed from a "potentiometer" to an "automatic potentiometric titrator" (see 4.3.2; 5.1 of the 2008 edition);

c) the sample treatment has been changed, "test sample" being changed to "sample" (see 4.4; Clause 6 of the 2008 edition);

d) a reproducibility requirement has been added (see 4.7.2);

e) the allowable difference requirement has been deleted (see 9.2 of the 2008 edition);

f) the fire assay gravimetric method has been added (see Clause 5).

Attention is drawn to the possibility that some elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.

This document was proposed by the China Nonferrous Metals Industry Association.

This document is under the jurisdiction of the National Technical Committee on Nonferrous Metals of Standardization Administration of China (SAC/TC 243).

Drafting organisations of this document: Sino-Platinum Metals Testing Technology (Yunnan) Co., Ltd., China Nonferrous Metals Technology and Economic Research Institute Co., Ltd., Yunnan Gold Mining Group Precious Metals Testing Co., Ltd., Yunnan Precious Metals New Materials Holding Group Co., Ltd., Sino-Platinum Resources (Yimen) Co., Ltd., BGRIMM Testing Technology Co., Ltd., Institute of Industrial Analysis and Testing, Guangdong Academy of Sciences, Shandong Humon Smelting Co., Ltd., Jiangxi Junxin Precious Metals Technology Materials Co., Ltd., Shandong Zhongjin Lingnan Copper Co., Ltd., Zijin Mining Group Co., Ltd., Chenzhou Product Quality Supervision and Inspection Institute, Nanjing Institute of Product Quality Inspection (Nanjing Institute of Quality Development and Advanced Technology Application), Changle Chengxin Gold Co., Ltd., and Jinchuan Group Co., Ltd.

Main drafters of this document: Yang Hui, Zhao Wanchun, Teng Long, Xiang Lei, Chen Xiaoke, Chen Lihua, Wang Haoying, Wu Zhuokui, Wang Lingyan, Yu Fengshan, Wang Xiao, Chen Zhuhai, Zhang Zhuojia, Gao Ruifeng, Zhang Qi, Wang Wei, Sun Qi, Jin Yaqiu, Feng Yanbo, Luo Xian, Song Kaiyue, Liu Wei, Zhang Xinya, Tian Dapeng, Chen Neng, Song Meng, Guo Yang, Yang Huadong, Li Bei, Ma Li, Li Qiuying, Li Li, Bai Xin, Zhu Wuxun, Qi Tao.

Previous editions of this document and of the documents it replaces:

— first published in 1994 and first revised in 2008;

— this is the second revision.

Introduction

Precious metal alloys are alloy materials composed of one or more precious metals (such as gold, silver, platinum and palladium) together with other metallic or non-metallic elements. These alloys not only retain the excellent properties of the precious metals, such as corrosion resistance, electrical conductivity and ductility, but also allow certain physical, chemical or mechanical properties of the alloy to be changed or enhanced by the addition of other metals. This makes precious metal alloys important for improving the practicality of materials and reducing cost, and they are widely used in the automotive industry, electronics and communications, new energy, petrochemicals, the ordnance industry, aerospace and other fields.

GB/T 15072 is intended to establish a set of standard methods for chemical composition analysis, to meet the needs of the production and trade of precious metal alloy products. GB/T 15072 is intended to consist of 20 parts:

— Part 1: Determination of gold content. The purpose is to establish potentiometric titration and fire assay gravimetric methods for the determination of gold content in precious metal alloys.

— Part 2: Determination of silver content. The purpose is to establish potentiometric titration and fire assay gravimetric methods for the determination of silver content in precious metal alloys.

— Part 3: Determination of platinum content. The purpose is to establish a potentiometric titration method for the determination of platinum content in precious metal alloys.

— Part 4: Determination of palladium content. The purpose is to establish gravimetric and titrimetric methods for the determination of palladium content in precious metal alloys.

— Part 6: Determination of iridium content. The purpose is to establish a potentiometric titration method for the determination of iridium content in precious metal alloys.

— Part 7: Determination of platinum, palladium, rhodium, iridium, ruthenium, cobalt, chromium, iron, nickel, zinc, copper, manganese, gadolinium, yttrium, tin, cerium, lanthanum, aluminium, vanadium, magnesium, gallium, beryllium, antimony, zirconium, molybdenum and titanium contents. The purpose is to establish an inductively coupled plasma atomic emission spectrometric method for the determination of multiple element contents in precious metal alloys.

— Part 8: Determination of copper content. The purpose is to establish a titrimetric method for the determination of copper content in precious metal alloys.

— Part 9: Determination of indium and zirconium contents. The purpose is to establish a titrimetric method for the determination of indium and zirconium contents in precious metal alloys.

— Part 10: Determination of nickel content. The purpose is to establish titrimetric and gravimetric methods for the determination of nickel content in precious metal alloys.

— Part 12: Determination of vanadium, rhenium, gadolinium and yttrium contents - Spectrophotometric method. The purpose is to establish a spectrophotometric method for the determination of vanadium, rhenium, gadolinium and yttrium contents in precious metal alloys.

— Part 17: Determination of tungsten content. The purpose is to establish a gravimetric method for the determination of tungsten content in precious metal alloys.

— Part 20: Determination of rhodium content. The purpose is to establish spectrophotometric and gravimetric methods for the determination of rhodium content in precious metal alloys.

— Part 21: Determination of ruthenium content. The purpose is to establish a spectrophotometric method for the determination of ruthenium content in precious metal alloys.

— Part 22: Determination of manganese content. The purpose is to establish a titrimetric method for the determination of manganese content in precious metal alloys.

— Part 23: Determination of cobalt content. The purpose is to establish a titrimetric method for the determination of cobalt content in precious metal alloys.

— Part 24: Determination of tin content. The purpose is to establish a titrimetric method for the determination of tin content in precious metal alloys.

— Part 25: Determination of copper, manganese, antimony and nickel contents - Flame atomic absorption spectrometry. The purpose is to establish a flame atomic absorption spectrometric method for the determination of copper, manganese, antimony and nickel contents in precious metal alloys.

— Part 26: Determination of oxygen, nitrogen and hydrogen contents. The purpose is to establish inert gas fusion - infrared absorption / thermal conductivity methods for the determination of oxygen, nitrogen and hydrogen contents.

— Part 27: Determination of carbon content. The purpose is to establish a high-frequency infrared detection method for the determination of carbon content.

— Part 28: Determination of trace element contents. The purpose is to establish an inductively coupled plasma atomic emission spectrometric method for the determination of trace element contents in precious metal alloys.

Since 1994, two editions of parts of the GB/T 15072 series have been published. GB/T 15072.1-2008 has been in force for more than ten years, and its measurement range no longer fully covers the technical requirements of products. It was therefore necessary to revise GB/T 15072.1-2008 to ensure that the standard keeps pace with changes in the industry and with market needs.

This document further improves the applicability of the standard: its measurement range fully covers the requirements of current product standards and meets market needs. It is of significance for improving the quality of precious metal alloy products and promoting their production, trade and wider application.

1 Scope

Warning - Persons using this document should have practical experience of working in a regular laboratory. This document does not purport to address all possible safety problems. It is the responsibility of the user to take appropriate safety and health measures and to ensure compliance with the conditions laid down by relevant national regulations.

This document describes the ferrous sulfate potentiometric titration method and the fire assay gravimetric method for the determination of gold content in precious metal alloys.

This document applies to the determination of gold content in precious metal alloys. Measurement range (mass fraction) of the ferrous sulfate potentiometric titration method: 3.00 % to 99.60 %; measurement range (mass fraction) of the fire assay gravimetric method: 5.00 % to 99.60 %.

The fire assay gravimetric method in this document applies to test samples with a total platinum group metal content of less than 0.005 %.

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.

GB/T 8170 Rules of rounding off for numerical values and expression and judgement of limiting values

3 Terms and definitions

No terms and definitions are listed in this document.

4 Method 1 - Ferrous sulfate potentiometric titration

4.1 Principle

The test portion is decomposed with nitric acid and hydrochloric acid; test portions containing platinum, rhodium or iridium are decomposed with hydrochloric acid and hydrogen peroxide in a closed vessel. Gold is separated from rhodium, iridium, tin, platinum, palladium and the matrix by reduction with copper(I) chloride. In a mixed sulfuric acid and phosphoric acid medium, Au(I) is reduced to Au(0) with ferrous sulfate standard titration solution, the end point being indicated potentiometrically, to determine the mass fraction of gold.

4.2 Reagents or materials

Unless otherwise stated, only reagents of recognised analytical grade and distilled water, deionised water or water of equivalent purity shall be used in the analysis.

4.2.1

Hydrochloric acid (rho = 1.19 g/mL).

4.2.2

Nitric acid (rho = 1.42 g/mL).

4.2.3

Sulfuric acid (rho = 1.84 g/mL).

4.2.4

Phosphoric acid (rho = 1.70 g/mL).

4.2.5

Hydrogen peroxide (rho = 1.10 g/mL).

4.2.6

Potassium permanganate solution (20 g/L).

4.2.7

Sulfuric acid solution (4 + 96).

4.2.8

Mixed hydrochloric and nitric acid solution: mix 3 volumes of hydrochloric acid (4.2.1) with 1 volume of nitric acid (4.2.2). Prepare immediately before use.

4.2.9

Mixed sulfuric and phosphoric acid solution: measure 200 mL of sulfuric acid (4.2.3) into a porcelain evaporating dish and heat until dense white fumes are evolved; while stirring, add potassium permanganate solution (4.2.6) dropwise until the red colour persists; remove from the heat and cool. Add 200 mL of phosphoric acid (4.2.4) and mix. Transfer to a 600 mL glass bottle.

4.2.10

Hydrochloric acid solution (1 + 9).

4.2.11

Sodium chloride solution (200 g/L).

4.2.12

Copper(I) chloride solution: weigh 3.0 g of copper(I) chloride into a 100 mL beaker, add 30 mL of hydrochloric acid (4.2.1), transfer to a 100 mL volumetric flask, dilute to the mark with water and mix. Prepare immediately before use.

4.2.13

Ferrous sulfate standard titration solution, prepared and standardised as follows:

a) Preparation: weigh 10.5 g of solid ferrous sulfate (FeSO4·7H2O) and dissolve it in a glass bottle containing 5 000 mL of sulfuric acid solution (4.2.7); mix, and allow to stand for one week before standardisation;

b) Standardisation: standardisation is carried out in parallel with the determination of the test portions.

Pipette 10.00 mL of gold standard solution into a 100 mL beaker, add 0.5 mL of sodium chloride solution (4.2.11), evaporate on a water bath to moist salts and remove. Add 5 mL of mixed sulfuric and phosphoric acid solution (4.2.9) and add water to about 40 mL. Place the beaker on the titration turntable, start the automatic potentiometric titrator, insert the electrode and burette connected to the titrator into the sample solution and stir for at least 20 s (for the instrument operating parameters see Annex A). Titrate potentiometrically with the ferrous sulfate standard titration solution to the end point. Determine the end point from the potentiometric titration curve or the dE/dV curve. Record the volume V2 of ferrous sulfate standard solution consumed at the end point. Carry out three parallel determinations; the range of the volumes of ferrous sulfate standard titration solution consumed in standardisation shall not exceed 0.020 mL, and the mean value is taken.

Calculate the actual concentration of the ferrous sulfate standard titration solution by formula (1):

c = (c0 × V1 × 10^-3) / (196.966 × V2) (1)

where:

c - actual concentration of the ferrous sulfate standard titration solution, in moles per millilitre (mol/mL);

c0 - mass concentration of the gold standard solution pipetted, in milligrams per millilitre (mg/mL);

V1 - volume of gold standard solution pipetted, in millilitres (mL);

196.966 - molar mass of gold, in grams per mole (g/mol);

V2 - volume of ferrous sulfate standard titration solution consumed in standardisation, in millilitres (mL).

4.2.14

Gold standard solution: weigh 0.2500 g of gold metal (wAu >= 99.99 %) into a 600 mL beaker, add 10 mL of mixed hydrochloric and nitric acid solution (4.2.8), cover with a watch glass and heat on a water bath until completely dissolved; remove. Rinse the watch glass and the beaker wall with a little water, add 0.5 mL of sodium chloride solution (4.2.11), evaporate on a water bath to moist salts and remove. Add 6 mL of hydrochloric acid (4.2.1), rinse the beaker wall with a little water and evaporate on a water bath to moist salts. Repeat 4 to 5 times and remove. Add 50 mL of hydrochloric acid (4.2.1), transfer to a 250 mL volumetric flask, dilute to the mark with water and mix. 1 mL of this solution contains 1 mg of gold.

4.3 Apparatus

4.3.1

Balance, sensitivity 0.01 mg.

4.3.2

Titration apparatus: automatic potentiometric titrator. For the instrument operating parameters see Annex A.

4.3.3

Oven (temperature not greater than 300 °C).

4.3.4

PTFE digestion vessel: wall thickness 25 mm ± 2 mm, capacity 30 mL; any digestion vessel meeting these conditions may be used.

4.4 Samples

The sample is machined into chips not more than 0.2 mm thick and not more than 2.0 mm long and wide. Soak the chips in glacial acetic acid for 10 min, then wash them clean with anhydrous ethanol, dry in air and mix.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 19 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 8170Rules of rounding off for numerical values & expression and judgement of limiting values

Cited by

Editions of GB/T 15072.1

Edition	Title	Revision	Status
GB/T 15072.1-2025	Methods for chemical analysis of precious metal alloys - Part 1: Determination of gold content	current edition	Current
GB/T 15072.1-2008	Test method of precious alloys -- Determination of gold content for gold, platinum and palladium alloys -- Potentiometric titration using ferrous sulfate	previous edition	In force
GB/T 15072.1-1994	Gold, palladium alloys. Determination of gold content	previous edition	Obsolete

This page sells the current edition, GB/T 15072.1-2025. Earlier editions are listed for reference only.

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