GB/T 21198.5-2007Determination of precious metals in precious metals jewellery alloys -- Method using ICP spectrometry -- Part 5: 999‰ silver jewellery alloys -- Determination of silver -- Difference method (English PDF)

Foreword

GB/T 21198 "precious metal jewelery alloys precious metal content using ICP spectrometry" is divided into six parts.

--- Part 1. Determination of platinum content platinum jewelery alloys using yttrium as internal standard;

--- Part 2. Determination of platinum content platinum alloy jewelry using platinum all trace elements and the intensity ratio method;

--- Part 3. Determination of palladium jewelery alloys using palladium content of yttrium as internal standard;

--- Part 4. Determination of 999 per mille precious metal jewelery alloys precious metal content of subtraction;

Part --- Article 5. 999 per mille silver jewelery alloys - Determination of silver content difference of subtraction;

--- Part 6. Subtraction.

This section GB/T 21198 Part 5.

The section referring to ISO/CD15096.2001 "999 per mille silver alloy of silver jewelry Determination ICP-OES Subtraction" written and ISO/CD15096 following main technical difference.

--- Due to the current international and domestic no standard for sample preparation, thus deleting the original text of Chapter 2, b Chapter 4 and Chapter 9);

--- According to our standard requirements for the preparation of reagents specifications made provisions;

--- Increased provisions for analytical balance.

For ease of use, this section also made the following editorial changes.

--- "This International Standard" be replaced by "this section";

"." --- With a decimal point instead of a comma as the decimal point, "";

--- With "mL" instead of "cm3";

--- Delete international standards foreword.

Appendix A of this section is an informative annex.

This part is proposed by the China National Light Industry Council.

This part of the National Standardization Technical Committee jewelry (SAC/TC256) centralized.

This section drafted by. National Jewelry Quality Supervision and Inspection Center.

1 Scope

This section GB/T 21198 specifies the silver content is determined by measuring the 999 per mille silver alloy jewelry in the content of impurity elements method.

This section applies to a silver content of 999 per mille silver alloy jewelry.

Note. The jewelry may contain platinum, palladium, gold, bismuth, cadmium, cobalt, copper, iron, iridium, nickel, lead, rhodium, ruthenium, antimony, selenium, tin, tellurium, titanium and zinc.

2 Principle of the method

Precious metal jewelery weighed sample was dissolved in nitric acid, 10g/L solution was prepared. Hydrochloric acid was added to precipitate the silver, chloride is separated by filtration. By ICP Spectrometer impurity content, the silver content is determined by subtraction.

3 Reagent material

Unless otherwise indicated in the analysis using only recognized as analytical grade reagents and distilled or deionized water or equivalent purity.

3.1 Hydrochloride. mass fraction of 36% ~ 38%, rho = 1.19g/mL.

3.2 nitric acid. mass fraction of 65% ~ 68%, rho = 1.40g/mL.

3.3 using a validated reagents to obtain an indication of the concentration of the mixed stock solution was prepared following.

3.3.1 nitrate stock solution (chloride free). bismuth, lead (respectively 100mg/L), in 2mol/L nitric acid (3.2) medium.

3.3.2 hydrochloride stock solution (containing no nitrate). tin, titanium (respectively 100mg/L), in 2mol/L hydrochloric acid (3.1) medium.

3.3.3 acid stock solution (can contain hydrochloric acid and nitric acid). contain related elements (respectively 100mg/L), in 1mol/L hydrochloric acid (3.1) and 1mol/L nitrate (3.2) media.

NOTE. In addition to the solution 3.3.3, but can be added to any element required in 3.3.1 or 3.3.2 solution, the condition is not to introduce chloride in 3.3.1, and do not Nitrate introduced in 3.3.2.

3.4 Internal standard solution. It has been found suitable as scandium and yttrium internal standard solution.

3.5 silver wire or sheet. purity of not less than 999.9 per mille, should determine the content of each impurity element.

4 Instrument

Conventional laboratory instruments and equipment following

4.1 Inductively coupled plasma atomic emission spectroscopy (ICP spectrometer for short). with fixed or scanning channels, optical resolution of related elements is 0.02nm, the limit of detection is better than 0.05mg/L, with a background correction.

The detector was a photomultiplier tube or a semiconductor chip (CID, CCD) can be used to analyze the instrument.

NOTE. Appendix A is recommended wavelength.

4.2 microbalance. a sense of the amount of 0.01mg.