This standard specifies the analysis method for the gold content of jewelry, and the determination of the gold content of various gold and K-gold jewelry with a rough sample (the sample does not contain platinum, rhodium and other substances insoluble in nitric acid) with a composition content of 33.30% to 99.95%. This standard is the arbitration method for the analysis of the gold content of jewelry. GB/T 9288-1998 Analysis method for the gold content of jewelry GB/T9288-1998 Standard download decompression password: www.bzxz.net

GB/T 9288—1998
This standard is the arbitration method for the analysis of the gold content of jewelry. According to the actual situation of gold jewelry products in my country, this standard adopts the international standard ISO11426:1993 "Analysis Method for Gold Content of Jewelry" in a non-equivalent manner. Compared with the international standard, its scope of application is wider. After revision, this standard supplements the inspection conditions of white K gold and the types of ash tray materials.
This standard was first issued on June 4, 1988 and revised for the first time in March 1998. This standard was proposed by the China Light Industry Federation.
This standard is under the jurisdiction of the National Jewelry Standardization Center. The drafting unit of this standard: National Jewelry Quality Supervision and Inspection Center. The main drafters of this standard: Li Xiuying, Fan Jifang, Shen Feng. This standard is entrusted to the National Jewelry Standardization and Promotion Center for interpretation. Y
1 Scope
National Standard of the People's Republic of China
Analyse method of gold content in jewellery
Analyse method of gold content in jewelleryGB/T9288-1998
neq ISO 11426:1993
Replaces GB9288--88
This standard specifies the analysis method of gold content in jewellery, and the determination of gold content of various gold and K gold jewellery with a crude sample (the sample does not contain platinum, etc., which are insoluble in nitric acid) with a composition content of 33.30% to 99.95%. This standard is the arbitration method for the analysis of gold content in jewellery. 2 Definitions
This standard adopts the following definitions.
2.1 Copellation
Oxidation smelting process above the melting point of metal oxides. 2.2 Parting of gold
The silver in the gold-silver alloy particles after ash blowing is dissolved with nitric acid to achieve the process of separating gold and silver. 3 Method summary and principle
The method adopted in this standard is fire assay. Add an appropriate amount of silver to the sample, use lead as a scavenger, and place it in porous ash to oxidize and ash blow. Lead oxides and impurities are absorbed by the ash dish, while gold and silver remain in the ash dish. After separating the gold with nitric acid, weigh the weight of gold. 4 Reagents and materials
4.1 Electrolytic silver: purity is above 99.99%. 4.2 Lead (HGB8229): reagent pure, pure lead particles are melted and cast into 0.2mm thick lead foil, wipe off the oil and set aside. 4.3 Standard gold: purity is above 99.99%. 4.4 Nitric acid (GB626): analytical pure. Preparation: The volume ratio of nitric acid to water is 1*1 and 21. 4.5 Water: deionized water.
4.6 Ash III: bone ash or ash blood materials with similar absorption can be used to make each ash III with a lead absorption of more than 10g (the reference size of the ash blood is 30mm in outer diameter, 27mm in inner diameter, 20mm in height, and 10mm in concave depth). 5 Instruments and equipment
5.1 High temperature furnace: the temperature difference is less than ±20℃. 5.2 Automatic temperature control electric furnace: 1kW.
5.3 Small sheet rolling machine: the minimum rolling thickness is less than 0.1mm5.4 Ash dish rolling mold.
5.5 Three analytical balances: sensitivity 0.01mg, 0.1mg, 1mg; accuracy level: Level 2. 5.6 Furnace tools:
a) Long-handled stainless steel pliers;
Approved by the State Administration of Technical Supervision on March 25, 1998 and implemented on January 1, 1999
b) Gray III stainless steel pliers;
c) Stainless steel tweezers;
d) Medium hammer;
e) Iron anvil;
f) Digital steel stamp.
5.7 Gold-dividing tools
a) 250~500mL beaker;
b) Small glass rod with a diameter of 2.5~~3.0mm; www.bzxz.net
c) 100ml measuring cylinder;
d) Washing bottle;
e) Porcelain crucible;
f) Surface blood;
g) Gold-dividing basket (made of platinum or stainless steel sheet). 6 Analysis steps
6.1 Weighing
GB/T 9288--1998
6.1.1 Weigh 3.5~4.0g of pure lead foil per portion, the number of which is the sum of the number of standard gold and the sample. 6.1.2 Use an analytical balance with a sensitivity of 0.1mg to weigh 2.1~~2.5 times the amount of gold (the same proportion should be the same for the same test), the number of which is the sum of the number of standard gold and the sample, and put them into the pure lead foil respectively. 6.1.3 Accurately weigh 3~4 portions of standard gold of 0.30000~0.50000g and 3~4 portions of sample equivalent to 0.30000~0.50000g of gold. Add the same metal as the sample (purity of 99.99% or more) to the standard sample and put them into the lead foil respectively. 6.1.4 Wrap the weighed sample and standard gold with lead foil, roll them into a ball, and number them. Arrange the sample and standard sample crosswise to avoid errors caused by uneven furnace temperature and prepare for ash blowing.
6.2 Ash blowing
6.2.1 Place the ash dish in the high-temperature furnace and turn on the power. 6.2.2 When the furnace temperature rises to 920-1100℃ (the temperature depends on the sample, and the temperature of white K gold is higher), cut off the power, open the furnace door, and put the standard sample and sample into the ash blood with long-handled stainless steel pliers in the arranged order, close the furnace door, turn on the power, keep the temperature at 920-1100℃, and after 20-30 minutes, open the furnace door slightly to blow the oxidation ash. Close the furnace door after 10-15 minutes, and cut off the power after 45-60 minutes, and the ash blowing is completed. Cool down and reduce the furnace temperature to below 700℃. 6.3 Annealing and rolling
Take out the standard sample and the sample whose temperature has dropped below 700℃ from the ash and beat them with a hammer until they are easy to roll. Anneal them while beating them. Finally, roll them into thin sheets of about 0.15~~0.20mm. Mark them with digital steel stamps and roll them into spiral round shapes and put them into beakers (gold separation baskets). 6.4 Gold separation
6.4.1 The first gold separation: Pour 100~~150mL of nitric acid (1:1) preheated to 90~~95℃ into the beaker containing the sample (preferably using a gold separation basket), heat for about 45min, and wash with hot water at 60~80℃ for 3~~5 times. 6.4.2 The second gold separation: Pour 100~150mL of nitric acid (2:1) preheated to 90~95℃ into the beaker containing the sample, heat for 40min, pour out the acid solution, and wash with hot water for 3~~5 times. 6.4.3 The third gold separation (if there is no palladium in the sample, the third gold separation is not required): perform the operation content of 6.4.2, heating time 30min, washing 5~7 times.
6.4.4 Dry in a porcelain crucible, burn to golden yellow, cool and weigh. 7 Calculation and expression of analysis results
The percentage of gold (%) is calculated according to formula (1): 5
Wherein: Au-
GB/T 9288-1998
Au(%)=A-(B-BXE)
-gold content of the tested sample, %;
mass of the sample, g;
-mass of gold obtained after analyzing the sample, g; B---mass of standard gold, g
B,——mass of gold obtained after analyzing the standard gold, g; E-standard gold content, %.
8Tolerance
99.90~99.95
Below 99. 90
White K gold
Tolerance, %　
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