QB/T 1656-1992 Chemical analysis methods for platinum jewelry - Determination of palladium, rhodium and platinum content
Some standard content:
1. Content and scope of application
Industry standard of the People's Republic of China
Chemical analysis method of platinum jewelry
Determination of palladium, argon and platinum
QB/T 1656-92
This standard specifies the chemical analysis method of the content of palladium, argon and platinum in platinum jewelry. This standard is applicable to the determination of palladium, argon and platinum in argon jewelry with a content of 95.0%~99.5%, a palladium content of 0.5%~5.0% and a content of 0.1%~2.0%.
2. Method and principle
This standard uses ammonium chloroplatinate to gravimetrically determine the main platinum, and the residual micro-platinum in the filtrate is determined by stannous chloride colorimetry. The sum of the two parts of platinum is the platinum content of the sample. The content is determined by the butadiene nitride gravimetric method. The argon content is determined by the stannous nitride colorimetric method.
Dissolve the sample in water, oxidize and hydrolyze with sodium bicarbonate, adjust the pH value with sodium bicarbonate, and separate the palladium from the platinum in the form of hydrated oxide. Dissolve the palladium hydrate in hydrochloric acid and add diethanol solution, and determine the palladium content by diethanolamine palladium gravity method. The filtrate after palladium removal is measured by stannous nitride colorimetry. The main platinum is determined by saturated ammonium nitride in the liquid phase after palladium hydrate is removed, and the residual micro-platinum is determined by stannous nitride colorimetry. The sum of the two parts of platinum is the platinum content in the sample. 3 Reagents and materials
3.1 Hydrochloric acid (GB622)
3.2 Nitric acid (GB626)
Analytical grade.
Analytical grade.
3.3 Ethanol (GB678)
3.4 Sodium bicarbonate (GB 640)
Stannic nitride (GB638)
Ammonium chloride (GB658)
Sodium chloride (GB1266)
Sodium bromate·Analytically pure.
Butanediol·Analytically pure.
Analytically pure.
Analytically pure.
Analytically pure.
Analytically pure
Pure platinum (containing more than 99.95% platinum) spectrally pure. 3.11
Potassium chloroformate solution (containing 2% chloroform for standard use). 4 Instruments and equipment
4.1 Analytical balance. Sensitivity 0.1mg, accuracy level 3. 4.2 Horse caravan stove cover. Temperature 0～1300℃. Approved by the Ministry of Light Industry of the People's Republic of China on 1993-01-15 and implemented on 1993-09-01
Per ancestor explosion and overflow 0～300
4.4 Spectrophotometer wavelength 420~700mm. 4.5 Vacuum pump exhaust rate 1L/
4.6 Temperature-controlled water electric furnace 1W.
4.7 Second core funnel G4, 40ml.
4.8 Porcelain 30ml.
Suction flask 500ml
4.10 Beaker 100, 250, 300ml
Q8/T 1656.-92
Volume flask, 50, 100.500ml, first level. Measuring cylinder 10, 20ml.
Pipette 1, 5, 10, .50ml, grade.
Desiccator 5.L.
Glass funnel -.8 cm,
Medium speed quantitative paper: 12.5cm.
Fine test paper p7.6～8.5
General test paper pH1～14.
5 Determination of palladium
5.1 Analysis steps
5.1.1 Weigh 0:5000 of the sample with a split balance and place them in 300ml beakers respectively. 5.7.2 Add 20l of positive water and place it on a small electric stove to dissolve it with slight heat, then add 6ml of 10% sodium hydroxide solution and evaporate it until it is almost, then add 5ml of hydrochloric acid and evaporate it, repeat this three times to remove nitric acid, and add 100～150ml of water to dissolve it. 5.1.3 Boil the test solution until it is almost boiling, add 20ml of 10% sodium bromate solution and boil for 30min. Stir continuously with a glass rod, add 5% sodium bicarbonate solution dropwise until a large amount of dark brown precipitate is produced (pH 6-7), add 10ml of 10% sodium pyrophosphate solution and boil for 16min, add 5% sodium hydrogen phosphate solution dropwise to adjust the pH to 8±0.5, and keep the solution in a micro-state for 30min. 5.1.4 Remove and cool, and age for 60-90min. 5.1.5: Use a G4 sand core funnel to filter, wash the beaker with 1% sodium chloride solution and precipitate 5-6 times (the washing liquid and the filtrate are combined for platinum analysis).
5.1.6 Move the funnel with precipitate to another suction filtration bottle, add 10ml of hydrochloric acid to dissolve all the precipitate, wash the funnel with water 5-6 times, and transfer the solution to the original beaker.
5.1.7 After the solution is steamed on a small electric stove with slight heat until it is nearly dry, in order to completely separate the palladium and platinum, add 100 ml of water and use the above method to hydrolyze and precipitate with sodium bromate (the filtrate and washing liquid are combined with the first filtration and plated, leaving the analysis of platinum). 5.1.8 The washed precipitate is dissolved with 10 m2 of hydrochloric acid and almost dry, then 5 ml of hydrochloric acid is added and evaporated to almost dryness, and this is repeated 3 to 5 times to completely destroy the sodium bromate, and then 5 ml of hydrochloric acid is used to dissolve. 5.1.9 Add 101-150 ml of water and place to cool, add 10-15 ml of diethyl ethanol solution while stirring continuously, stir for 10 minutes, and place for 10 minutes.
5.1.10. Filter with a G4 sand core bucket that has been weighed to a constant weight, select the precipitate with 1% hydrochloric acid 5 to 6 times, then wash with water 5 to 6 times, and dry. bZxz.net
087T1656-92
5.1.11 Place the funnel in an oven and dry at 105~110°C for 80~90m. 5.1.12: Cool to constant weight.
5.2 Expression of analysis results
The percentage of palladium is calculated by the following formula:
(WeW) × 0-3161 × 100
Pd (%)
W,--total mass of funnel and precipitate, B--mass of funnel,
0.3161--coefficient for converting di-butanedipalladium into palladium, Wtotal--mass of sample, B.
:5.3 Precision
The error of the analysis result is less than 0:1%.
Determination of 6% stannous hydride
6.1 Preparation before analysis
(1)
6.1.1 Preparation of stannous hydride standard solution
Use a pipette to draw 6 ml of 2% potassium hydride standard sugar solution into a 50 ml volumetric flask, dilute to the mark with 1:5 hydrochloric acid, and shake to mix. Each ml of standard solution contains 2.5 g of stannous hydride solution. 6.1.2 Preparation of 25% stannous hydride solution
Use a pharmaceutical balance to weigh 25 g of stannous fluoride, dissolve it in 20 ml of hydrochloric acid, dilute to 100 ml with water, and store it in a brown bottle for later use.
6.1.3 Drawing of working curve
Use 1ml pipette to take 0.00, 0.10, 0.20, 0.30, 0.40, 0.50ml of standard solution respectively, and place them in six 50ml volumetric flasks respectively, add 10ml of 25% stannous nitride solution and shake the flask in boiling water and heat for 30min, take it out and cool to temperature, dilute to scale with 5% hydrochloric acid, and shake. Place the above standard solutions in 1em colorimetric essence respectively, use blank solution as reference at 475nm of spectrophotometer, measure its absorbance, and draw a working curve. 6.2 Analysis steps
.6.2.1 After removing palladium, the filtrate and washing solution are combined and transferred into a 500ml volumetric bottle, diluted to scale with water, and shake. 6.2.2 Use a pipette to pipette 50ml of the test solution into a 250ml beaker and add 9ml of hydrochloric acid. Add 3ml of caustic soda and evaporate until almost molten, breaking the nitric acid. Then add 5ml of salt solution and evaporate until almost molten. Repeat three times to remove the nitric acid. 6.2.3 Dissolve it with 25ml of 1:5 hydrochloric acid, transfer it into a 50ml volumetric flask, add 10ml of 25% stannous fluoride solution, and shake. 6.2.4 Soak the flask in water and heat for 30 minutes, take it out and put it in cold water to cool to room temperature, dilute it with 1:5 hydrochloric acid to degrees, and shake.
6.2.5 Place the test solution in a 1cm colorimetric cell and measure its absorbance with the reagent blank reference solution at 475mm of the spectrophotometer.
6.2.6. Find the corresponding energy on the working line. 6:3 Expression of analysis results
The percentage of tin is calculated by the following formula:
Q8/T 1650--92
Wherein: W is the mass found on the working curve, more than; W is the mass of the sample taken, more than.
6.4 Precision.
The error of the analysis result is less than 0.05%.
7 Determination of platinum
7.1 Preparation before analysis
7.1.1 Preparation of 10% stannous nitride solution
Weigh 10g of stannous nitride and dissolve it in 20ml of hydrochloric acid, cover it in a 100ml volumetric flask, dilute it to the mark with water, shake the spoon (this solution should be transparent and free of turbidity, and can be used for one week after preparation). 7.7.2 Preparation of platinum standard solution
Weigh 0.Put 1000g in a 100ml beaker, add 10ml of Wang Yong to dissolve and evaporate to nearly dryness, then add 5ml of hydrochloric acid and evaporate to nearly dryness, repeat this three times to remove nitrogen-supported compounds, then dissolve with 10ml of hydrochloric acid, transfer to a 100ml volumetric flask, dilute to the scale with water, shake the spoon, and the platinum content per milliliter is 1mg: b. Use a pipette to draw 1ml of the above platinum standard solution into a 100ml volumetric flask, add 2ml of hydrochloric acid, dilute to the scale with water, shake the spoon, and the platinum content per milliliter is 0.01mg. 7.1.3 Drawing of working curve
Use a pipette to take 0.00, 2.00, 4.00, 6.00, 8.00, 10.00 ml of the platinum standard solution prepared in 7.1.2b, and place them in six 50 ml volumetric flasks respectively. Add 8 ml of hydrochloric acid, 10 ml of 20% ammonium nitride solution and 5 ml of 10% stannous chloride solution, shake, dilute to the mark with water and shake well. Use 1 cm colorimetric precision to measure its absorbance at a wavelength of 4521 nm on a spectrophotometer, and draw a working curve.
: 7.2, Analysis steps
7.2.1 Add 20 ml of hydrochloric acid to the filtrate collected after removing palladium, heat and concentrate to near dryness, then add 5 ml of hydrochloric acid and evaporate to near flatness, repeat this three times to make the sodium aureate gold partly destroyed. 7.2.2. Add 10ml hydrochloric acid and 40ml water, heat and boil until all salts are dissolved, and cool. 7.2.3 Add 50ml saturated ammonium fluoride solution while stirring continuously, and let stand overnight. 7.2.4 Filter with quantitative filter paper, wash the precipitate with saturated ammonium chloride solution 6 to 7 times, collect the filtrate and washing solution in a 500ml container, dilute to the scale and keep it for micro-adjustment of platinum. 7.2.5 Put the filter paper and precipitate together in a constant weight porcelain crucible, and ash them. 7.2.6 Put the porcelain crucible into a muffle furnace and burn it at 900℃ for 90min. 7.2.7 Take out the porcelain crucible, put it in a desiccator to cool, and keep constant weight. 7.2.8 The mass of platinum is calculated as follows:
W is the total mass of platinum and porcelain crucible, B: W is the mass of porcelain crucible,
is the mass of filling, g.
Q8 165692
7.3 Analysis steps of micro-platinum in filtrate
7.3.1 Use a pipette to draw 10ml of the filtrate collected in the 500μl bottle (see 7.2.4) into a 50ml volumetric flask, add 8ml of hydrochloric acid. Add 6ml of 10% tin nitrogen solution, spread evenly, and dilute to the scale. 7.3.2 Use a 1cm colorimetric cell at 452nm on the spectrophotometer, and use the reagent blank as the reference solution to measure its absorbance. 7.3.3 Find the corresponding platinum mouse on the standard working curve and calculate the mass W of the micro-platinum in the solution. 7.4. Expression of analysis results
The percentage of platinum is calculated as follows:
Pt (%)
Wa+Wax100+
Where: W—mass of platinum measured by gravimetric method, g;
—mass of sample, g.
7.5 Precision
The tolerance of analysis results is less than 0.2%.
Additional remarks:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Jewelry Standardization Center. This standard is drafted by the Beijing Institute of Arts and Crafts. The main drafter of this standard is Li Xiuying.
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