GOST 27973.2-88

• gost-279732-88.pdf (271.45 KiB)
  ГОСТ 27973.2-88

GOST 27973.2−88 Gold. Method of atomic-emission analysis with inductive plasma

GOST 27973.2−88

Group B59

INTERSTATE STANDARD

GOLD

Method of atomic-emission analysis with inductive plasma

Gold. Method of atomic-emission analysis with inductive plasma

AXTU 1709

Date of introduction 1990−07−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED the Main Directorate of precious metals and diamonds at the Council of Ministers of the USSR

DEVELOPERS

Yu. a. Karpov, Dr. chem. Sciences (head of subject); O. I. Shiryaeva, PhD. chem. Sciences; L. N. Ryazanov, V. I. Baluda; I. N. Vladimir; Sergey V. Sokolov

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 21.12.88 N 4375

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)

6. REPRINTING. June 1999


This standard specifies atomic emission (with an induction high-frequency plasma) method for determination of impurities, silver, copper, iron, platinum, palladium, rhodium, bismuth, lead, antimony, zinc, manganese, Nickel, chromium and tin in gold with a mass fraction of gold is not less than 99.9%.

The method is based on excitation of atoms of the sample in RF induction plasma and measuring the intensity of the analytical spectral line of the element during the spraying of the solution of the sample into the plasma. The relationship of the intensity of lines with the concentration of the element in the solution set with the help of calibration curve.

The method allows to determine the mass fraction of impurities in the intervals given in table.1.

Table 1

The error analysis results the determined values of mass fractions of impurities with the confidence coefficient =0.95 is given in table.2.

Table 2

1. GENERAL REQUIREMENTS

General requirements for method of analysis according to GOST 27973.0.

2. APPARATUS, REAGENTS AND MATERIALS

Spectral-analytical complex, consisting of HF generator with a capacity of 0,8−1,5 kW plasma torch spray system, quantometer (polychromator) or monochromator with inverse linear dispersion is not worse than 0.5 nm/mm and photoelectric registration of radiation intensity, a control computer, display and printer.

Argon gas according to GOST 10157.

Analytical scales of the 2nd class.

Muffle furnace with thermostatic control.

Electric stove with a closed spiral.

Autoclave analytical.

The agate mortar.

Heat-resistant glasses with a capacity of 100 and 250 cmaccording to GOST 25336.

The corundum crucibles.

Pipettes with a capacity of 1, 2, 5 and 10 cmwith the divisions of NTD.

Volumetric flasks with a capacity of 50 and 100 cmaccording to GOST 1770.

Obestochennye the filter paper of «blue ribbon» «white ribbon».

Hydrochloric acid of high purity according to GOST 14261 and diluted 1:1, 1:5 and 1:9.

Nitric acid of high purity according to GOST 11125 and diluted 1:1.

Sulfuric acid of high purity according to GOST 14262 and diluted 1:9.

Barium peroxide according to normative-technical documentation.

Gold of high purity with a mass fraction of gold is not less than 99.999%.

Silver GOST 6836*.
_______________
* On the territory of the Russian Federation GOST 6836−2002. — Note the manufacturer’s database.

Radio engineering carbonyl iron according to GOST 13610.

Copper according to GOST 859*.
_______________
* On the territory of the Russian Federation GOST 859−2001. — Note the manufacturer’s database.

Bismuth GOST 10928.

Lead of high purity according to GOST 22861.

Zinc GOST 3640.

Antimony GOST 1089.

Manganese metal according to GOST 6008.

Nickel GOST 849.

Tin GOST 860.

Chrome metal according to GOST 5905.*
_______________
* On the territory of the Russian Federation GOST 5905−2004. — Note the manufacturer’s database.

Palladium powder according to GOST 14836*.
_______________
* On the territory of the Russian Federation from 01.01.2008 standards 31291−2005. — Note the manufacturer’s database.

Platinum powder according to GOST 14837*.
_______________
* On the territory of the Russian Federation from 01.01.2008 standards 31290−2005. — Note the manufacturer’s database.

Rhodium powder according to GOST 12342 or rhodium trichloride cetarehwodie.

Standard samples of gold.

2.1. The basic preparation of standard solutions

Standard solutions containing 1 mg/cmof bismuth, copper, Nickel, lead and iron: a portion of each of these metals with a weight of 100 mg dissolved in 10 cmof nitric acid (1:1) under heating. The solution was boiled to remove oxides of nitrogen, transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with water and mix.

A standard solution containing 1 mg/cmof silver: a sample of metal weighing 100 mg was dissolved in 10 cmof nitric acid (1:1) under heating. Then add 50 cmof hydrochloric acid and boil to complete dissolution of the precipitate of silver chloride. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:1) and stirred.

Standard solutions containing 1 mg/cmzinc, chromium and manganese: a sample mass of 100 mg of each of these metals is dissolved in 10 cmof hydrochloric acid (1:1) under heating. The solutions were transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:9) and stirred.

A standard solution containing 1 mg/cmof antimony: a portion of metallic antimony with a mass of 100 mg was dissolved in 20 cmof a mixture of hydrochloric and nitric acids (3:1) under heating, the solution is evaporated to a volume of 2−3 cm, add 20 cmof a hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with the same acid solution and stirred.

A standard solution containing 1 mg/cmtin: a sample of metal weighing 100 mg was dissolved in 10 cmof a mixture of hydrochloric and nitric acids (3:1) under heating, the solution was transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:9) and stirred.

A standard solution containing 1 mg/cmof platinum: a sample of platinum weighing 100 mg was dissolved in 20 cmof a mixture of hydrochloric and nitric acids (3:1) under heating, the solution is evaporated to a volume of 3−5 cm, flow 20 cmof a hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with the same acid solution and stirred.

A standard solution containing 1 mg/CCof palladium: a sample of palladium weighing 100 mg was dissolved in 10 cmof nitric acid by heating, the solution is evaporated to a volume of 3−5 cm, flow 20 cmof a hydrochloric acid solution (1:5), transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with the same acid solution and stirred.

A standard solution containing 1 mg/cmrhodium, prepare one of the following ways.

A portion of rhodium (in powder form) weighing 100 mg was thoroughly stirred with a fivefold quantity of peroxide of barium, fray in an agate mortar, transferred to a corundum crucible and sintered in air for 2−3 hours at a temperature of 800−900 °C (the crucible is put in a cold muffle). Sintered is cooled, transferred to a beaker with a capacity of 200 cm, moistened with water and dissolved in a solution of hydrochloric acid (1:1) until complete dissolution. If, after the dissolution of SPECA in hydrochloric acid is a residue, sintering and dissolution repeat. The resulting solution is diluted with water to a volume of 50 cmand precipitated barium sulfate by adding sulfuric acid solution (1:9) portions with constant stirring. The solution is heated to a temperature of 60−70 °C. after 2−3 hours check the completeness of the precipitation of the barium sulfate and filter it through filter «blue ribbon», or double filter «white ribbon» in a volumetric flask with a capacity of 100 cm. The filter cake was washed 4−5 times with hot hydrochloric acid (1:5), and then 5−6 times with hot water. The solution was adjusted to the mark with hydrochloric acid (1:5) and stirred.

A suspension of rhodium trichloride ground 273,4 mg dissolved in 20 cmof a hydrochloric acid solution (1:1) at weak heating, the solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with hydrochloric to

islote (1:5) and stirred.

2.2. Preparation of standard solutions containing an amount of the determined elements

Solution a: in a volumetric flask with a capacity of 100 cmplaced 1 cmcore of standard solutions of silver, platinum, palladium, rhodium, iron, copper, bismuth, chromium, manganese, Nickel, tin, antimony, lead and zinc, add 20 cmof hydrochloric acid, adjusted to the mark with water and mix. 1 cmof the solution contains 10 µg each of the identified elements. The solution is stable for one month.

Solution B: in a volumetric flask with a capacity of 100 cmis placed 10 cmsolution A, was adjusted to the mark with hydrochloric acid (1:5) and stirred. 1 cmof the solution contains 1 µg of each of the identified elements. Solution B is prepared on the day of application.

3. PREPARATION FOR ASSAY

3.1. The dissolution of samples in an open system

To perform the analysis selected for two whole gold weight of 0.5−1.0 g each were placed in a glass with a capacity of 50−100 cm, clean the gold surface in accordance with GOST 27973.0, add 10−20 cm ina freshly prepared mixture of hydrochloric and nitric acids (3:1) and dissolve the metal under the watch glass under low heat. After dissolution, the sample solution is evaporated to a volume of 4−5 cm, add 20 cmof a hydrochloric acid solution (1:1), transferred to a volumetric flask with a capacity of 50 cm, adjusted to the mark with water and mix.

At the same time through all stages of the analysis carried out control and experience on the purity of the reagents.

3.2. Dissolution of the samples in a closed system

Take two sample of gold with a mass of 0.5−1.0 g each of which is placed in the inner Cup Teflon autoclave. Clean the gold surface according to GOST 27973.0, add 2−3 cm ofa freshly prepared mixture of hydrochloric and nitric acids (3:1), the autoclave was sealed and placed in a drying Cabinet. The dissolution is conducted at a temperature not exceeding 160 °C for 2 h.

The autoclave is removed from the oven, cooled and the contents transferred to a glass volumetric flask with a capacity of 50 cm, adding 20 cmof a hydrochloric acid solution (1:1). The volume in the flask was adjusted to the mark with water and mix.

3.3. Preparation of solutions comparison

For the determination of impurities in gold use solutions comparison, containing all the trace elements and gold.

Solution containing 50 mg/cmof gold is prepared by dissolving the weighed portion of high purity gold weight of 5.0 g according to claim 4.1. The solution of gold is transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with hydrochloric acid (1:5) and stirred.

Solutions comparison with the mass concentration of each of the designated impurities 0,02, 0,04, 0,06, 0,08, 0,1, 0,2, 0,4, 0,6, 0,8, 1,0, 2,0 µg/cmand gold — 10 mg/cmin volumetric flasks with a capacity of 50 cmplaced at 10 cmsolution of gold containing 50 mg/cmgold aliquote parts of solutions A or B (tab.3), adjusted to the mark with hydrochloric acid (1:9) and stirred.

Table 3

4. ANALYSIS

Spectral-analytical complex ready to work and include according to «Working instruction manual of the device» (RI).

Wavelength of analytical spectral lines are given in table.4.

Table 4

Successively introduced into the plasma solutions and comparison with the help of a special program using the least squares method to get the numerical values of the coefficients of the polynomials approximating the calibration characteristics for each of the identified elements that enter into long-term memory of the computer.

The calibration characteristics is obtained in the coordinates of (-) where  — intensity of the analytical line of the element minus the intensity of the emission spectrum for the solution in the reference experiment at the wavelength of the analytical line of the element; is the concentration of the element in solutions comparison, µg/cm.

Solutions of samples analysed successively introduced into the plasma and measure the intensity of the analytical lines of the determined elements. In accordance with the program for each solution, perform 3 measurements of the intensity and calculate the average value, which using the calibration characteristics find the concentration of element (µg/cm) in the sample solution.

5. PROCESSING OF THE RESULTS

Mass fraction of the element () in percent is calculated by the formula

,

where is the mass concentration of the analyzed element in the sample solution, µg/cm;

 — the volume of the sample solution, cm,

 — the weight of the portion of the sample,

The analysis result should be the arithmetic mean of two parallel definitions, each of which is made of a separate hinge.

6. CONTROL OF ACCURACY OF ANALYSIS RESULTS

6.1. Under the control of the convergence and divergence of reproducibility of results of parallel measurements and the results of the two analyses (the difference between larger and smaller) with the confidence coefficient =0.95 does not exceed the values of permissible differences given in table.5.

Table 5

For intermediate values of the mass fraction of permissible differences calculated using linear interpolation.

6.2. The accuracy of the analysis results is evaluated according to GOST 27973.0.