GOST R 56308-2014

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  ГОСТ Р 56308-2014

GOST R 56308−2014 Silver. Method of atomic-absorption analysis

GOST R 56308−2014

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

SILVER

Method of atomic-absorption analysis

Silver. Method of atomic-absorption analysis

OKS 77.120.99
AXTU 1709

Date of introduction 2015−07−01

Preface

1 DEVELOPED by the Open joint-stock company «Irgiredmet» (JSC «Irgiredmet»), State scientific center State scientific-research and design Institute of rare metals industry (Giredmet SSC), an Open joint stock company «Krasnoyarsk factory of nonferrous metals named after V. N. Gulidova» (OJSC Krastsvetmet)

2 SUBMITTED by the Technical Committee on standardization TC 304 «Noble metals, alloys, industrial jewelry products, secondary resources containing noble metals"

3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology of December 12, 2014 N 1994-St

4 INTRODUCED FOR THE FIRST TIME


Application rules of this standard are established in GOST R 1.0−2012 (section 8). Information about the changes to this standard is published in the annual (as of January 1 of the current year) reference index «National standards» and the official text changes and amendments — in monthly information index «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a future issue of information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet (gost.ru)

1 Scope

This standard applies to refined silver with a mass fraction of silver is not less than 99.8%.

The standard establishes the method of atomic-absorption determination of impurities, aluminum, bismuth, iron, gold, cadmium, cobalt, magnesium, manganese, copper, arsenic, Nickel, tin, palladium, platinum, rhodium, lead, selenium, antimony, tellurium, titanium, chromium and zinc in affilirovannomu silver. Requirements to chemical composition set in silver GOST 28595.

2 Normative references

This standard uses the regulatory references to the following standards:

GOST 123−2008 Cobalt. Specifications

GOST 804−93 primary Magnesium ingots. Specifications

GOST 849−2008 Nickel primary. Specifications

GOST 859−2014 Copper. Brand

GOST 860−75 Tin. Specifications

GOST 1089−82 Antimony. Specifications

GOST 1467−93 Cadmium. Specifications

GOST 1770−74 (1042−83 ISO, ISO 4788−80) Glassware volumetric laboratory glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 3640−94 Zinc. Specifications

GOST 3778−98 Lead. Specifications

GOST 4055−78 Reagents. Nickel (II) nitrate 6-aqueous. Specifications

GOST 4456−75 Reagents. Cadmium sulphate. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 5817−77 Reagents. Acid wine. Specifications

GOST 5905−2004 (ISO 10387:1994) metal Chrome. Technical requirements and delivery conditions

GOST 6008−90 metallic Manganese and nitrated manganese. Specifications

GOST 6835−2002 Gold and alloys on its basis. Brand

GOST 10157−79 Argon gaseous and liquid. Specifications

GOST 10298−79 Selenium technical. Specifications

GOST 10928−90 Bismuth. Specifications

GOST 11069−2001 primary Aluminium. Brand

GOST 11125−84 nitric Acid of high purity. Specifications

GOST 12342−81 Rhodium powder. Specifications

GOST 13610−79 carbonyl Iron radio. Specifications

GOST 14261−77 hydrochloric Acid of high purity. Specifications

GOST 14262−78 sulphuric Acid of high purity. Specifications

GOST 17614−80 Tellurium technical. Specifications

GOST 17746−96 spongy Titanium. Specifications

GOST 18289−78 Reagents. Sodium volframovich 2 water. Specifications

GOST 20448−90 liquefied hydrocarbon Gases fuel for household consumption. Specifications

GOST 22861−93 Lead of high purity. Specifications

GOST 23620−79 of Niobium pentoxide. Specifications

GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

GOST 28058−89 Gold bullion. Specifications

GOST 28595−90 Silver bullion. Specifications

GOST 29227−91 (ISO 835−1-81) oils. Pipettes are graduated. Part 1. General requirements

GOST 31290−2005 Platinum affilirovannaja. Specifications

GOST 31291−2005 Palladium refined. Specifications

GOST R 8.563−2009 State system for ensuring the uniformity of measurements. Techniques (methods) of measurements

GOST R ISO 5725−1-2002 Accuracy (trueness and precision) of methods and measurement results. Part 1. General provisions and definitions

GOST R ISO 5725−3-2002 Accuracy (trueness and precision) of methods and measurement results. Part 3. Intermediate indicators the precision of a standard measurement method

GOST R ISO 5725−4-2002 Accuracy (trueness and precision) of methods and measurement results. Part 4. The main methods of determining the correctness of a standard measurement method

GOST R ISO 5725−6-2002 Accuracy (correctness and precision) of methods and measurement results. Part 6. The use of precision values in practice

GOST R 52244−2004 Palladium refined. Specifications

GOST R 52245−2004 Platinum affilirovannaja. Specifications

GOST R 52361−2005 Control of the analytical object. Terms and definitions

GOST R 52501−2005 (ISO 3696:1987) Water for laboratory analysis. Specifications

GOST R 52599−2006 Precious metals and their alloys. General requirements for methods of analysis

Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or in the annual information index «National standards» published as on January 1 of the current year, and the editions of the monthly information index «National standards» for the current year. If replaced with a reference standard, which was given an undated reference, then it is recommended to use the current version of this standard, taking into account all enabled in this version modifications. If replaced with a reference standard, which is given a dated reference, it is recommended to use the version of this standard referred to above by year of approval (acceptance). If after approval of this standard in the reference standard, which is given a dated reference, a change affecting a provision to which reference, the provision is recommended to be applied without taking into account this change. If the reference standard is cancelled without replacement, the position in which reference is made to him, recommended to be used in part not affecting this link.

3 Terms and definitions

This standard applies the terminology according to GOST R 8.563, GOST R ISO 5725−1, GOST R 52361 and recommendations [1].

4 the essence of the method

The method of this standard is based on the evaporation and atomization of the solution into the flame of a gas burner or a graphite atomizer (the cell), the measurement of the atomic absorption analytical (resonant) spectral lines of the identified elements-impurities and subsequent determination of their content according to the calibration characteristics. The method allows to determine the content of impurities in the ranges given in table 1.


Table 1 — Ranges of mass fraction of detectable elements

Percentage

5 Accuracy (trueness and precision) of the method

5.1 indicators of the accuracy of the method

Indicators of accuracy of the method: limit of the interval in which with a probability of 0.95 is a margin of error of any of the plurality of analysis results , standard deviations of repeatability and reproducibility , the standard deviation of the intermediate precision , the values of the limit of repeatability , intermediate precision and reproducibility limit depending on the mass fraction of the element-impurities are shown in table 2.


Table 2 — indicators of the accuracy of the method (0,95)

For intermediate values of the mass fraction of detectable elements the values of precision find using linear interpolation according to the formula

, (1)

where  — the indicator of accuracy for the result of the analysis ; %;

, the values of precision, corresponding to the lower and upper levels of the mass fraction of detectable elements, between which is the result of the analysis, %;

 — the result of the analysis, %;

, the lower and upper levels of a mass fraction of elements, between which is the result of the analysis, %.

5.2 Correctness

Systematic error of the method at a significance level of 5%, established in accordance with the requirements of GOST R ISO 5725−4, at all levels of the mass fraction of detectable elements is insignificant.

5.3 Precision

Range of two results of determinations obtained for the same sample by one operator using the same equipment within the shortest possible time intervals that may exceed the specified in table 2, the limit frequency set in accordance with the requirements of GOST R ISO 5725−6, on average not more than once in 20 cases with proper use of the method.

Within a single laboratory result analysis of the same sample obtained by different operators using the same equipment on different days, can vary with the excess specified in table 2 of the limit of intermediate precision set in accordance with the requirements of GOST R ISO 5725−3, on average not more than once in 20 cases with proper use of the method.

The results of the analysis of the same samples obtained by two laboratories may vary with the excess specified in table 2 of the limit of reproducibility , established in accordance with the requirements of GOST R ISO 5725−1, on average not more than once in 20 cases with proper use of the method.

6 Requirements

6.1 General requirements for the analysis method, requirements for security of works — according to GOST R 52599.

6.2 To perform analysis allowed persons over the age of 18, trained in the prescribed manner and allowed to work independently on used equipment.

7 measuring instruments, auxiliary equipment, materials, reagents

7.1 measuring instruments

Laboratory scales with the measurement error not more than ±0,0003 g

Volumetric flasks 1−25−2, 1−50−2, 1−100−2, 2−25−2, 2−50−2, 2−100−2, 2−1000−2 according to GOST 1770.

Beakers capacity 50, 100, 250, 1000 cmaccording to GOST 1770.

Piston micropipettes with a capacity of 0.01, 0.02 and 0.05 cm.

Pipette 1−1-2−1, 1−1-2−2, 1−1-2−5, 1−1-2−10 according to GOST 29227.

Spectrometer for atomic absorption analysis with flame and/or graphite atomizers.

The spectral lamp with a hollow cathode for the designated elements and/or electrodeless discharge lamp for the determination of bismuth, arsenic, tin, selenium, antimony and tellurium.

Cylinder measuring capacity 10 cmaccording to GOST 1770.

7.2 accessories

Muffle furnace with temperature controller with heating temperature up to 1000 °C.

Electric stove with a closed coil and adjustable heating temperature up to 300 °C.

Drying oven with the temperature heating up to 150 °C.

7.3 Materials

Argon gaseous and liquid GOST 10157.

Acetylene, dissolved and gaseous GOST 5457.

Funnel lab according to GOST 25336.

Polyethylene tanks, polypropylene or Teflon with a capacity of 50, 100 cm.

Propane-butane in cylinders for technical GOST 20448.

Glasses glass with a capacity of 100, 250 and 400 cmaccording to GOST 25336.

Watch-glasses.

The agate mortar.

The corundum crucibles.

The filter paper obestochennye «blue ribbon» and «white ribbon» [2]*.
________________
* POS.[2], [3], [5] cm. Bibliography. — Note the manufacturer’s database.

7.4 Reagents

Aluminium metal according to GOST 11069.

Barium peroxide (barium peroxide) OS.h. in [3].

Buffer solution of sulphate of cadmium with a mass concentration of cadmium 5 g/DM: a portion of sulphate of cadmium with a mass of 11.4 g was placed in a volumetric flask with a capacity of 1000 cm, 500 cm pouredwater, stirring to dissolve the salt, bring the water volume up to the mark and mix.

Bismuth GOST 10928.

Water for laboratory analysis of the 1st grade according to GOST R 52501 (next to water).

Aqueous slurry of niobium pentoxide mass ratio of 1:5: the sample of niobium pentoxide by mass of 4.0 g add 20 cmof water and mix to a condition of the suspension.

Carbonyl iron, radio GOST 13610.

Gold bullion according to GOST 6835 or GOST 28058 with a mass fraction of main substance not less than 99.99%.

Cadmium metal according to GOST 1467.

Cadmium sulfate according to GOST 4456.

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

Tartaric acid according to GOST 5817, solution mass concentration of 10 g/DM.

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

Hydrochloric acid of high purity according to GOST 14261 and diluted 1:1, 1:5, 1:7, 1:20, 1:100.

Cobalt GOST 123.

Magnesium GOST 804.

Manganese metal according to GOST 6008.

Copper according to the GOST 859.

Arsenic metal, high purity [4].

Sodium volframovich 2-water according to GOST 18289.

Nickel GOST 849.

Nickel nitrate 6-water according to GOST 4055.

Of niobium pentoxide according to GOST 23620.

Tin GOST 860.

Palladium refined according to GOST R or GOST 52244 31291 with a mass fraction of the basic substance is not less than 99,98%.

Platinum affilirovannaja according to GOST R or GOST 52245 31290 with a mass fraction of the basic substance is not less than 99,98%.

A solution of Nickel nitrate (matrix modifier) with a mass concentration of Nickel, 1 g/DM: a portion of Nickel nitrate mass 0,494 g is placed in a volumetric flask with a capacity of 100 cm, 50 cm addwater, stirring to dissolve the salt, bring to the mark with water and mix.

Solution volframovich sodium mass concentration of tungsten 5 g/DM: volframovich a sample of sodium weighing 0.897 g is placed in a volumetric flask with a capacity of 100 cm, 50 cm addwater, stirring to dissolve the salt, bring to the mark with water and mix again.

Rhodium powder according to GOST 12342 with a mass fraction of basic substance is no less than a 99.97%.

Lead of high purity according to GOST or GOST 22861 3778.

Selenium technical GOST 10298.

Silver of high purity [5].

A mixture of hydrochloric and nitric acids in the ratio 3:1, freshly prepared.

Antimony GOST 1089.

Tellurium GOST 17614.

Titanium sponge according to GOST 17746.

Chrome metal according to GOST 5905.

Zinc GOST 3640.

Allowed the use of other measuring instruments, auxiliary equipment, materials and reagents, subject to obtaining the metrological characteristics are not inferior to those in table 2.

Solutions of reagents under this subsection stored in a sealed glass or plastic container at room temperature, the shelf life of the solutions is not limited. When using the solutions stored for more than a year, you should make sure there is no sediment, flakes, color change of the solution. Otherwise, replace with freshly prepared solutions.

8 Preparation for assay

8.1 Preparation of basic solutions

The following procedures for preparing basic solutions indicate the mass of batches of materials with a purity not lower of 99.96%. In the case of the use of chemicals with purity lower than 99.96%, then the correction of the mass of sample in accordance with a mass fraction of basic substance, specified in the passport in reagent.

The prepared solutions were stored at room temperature in sealed containers of glass and/or plastic not more than one year.

On the containers of solutions must be pasted label with the indication of the name or symbols of elements mass concentration of elements and limit of absolute error of its establishment, date of preparation and shelf life of the solution.

8.1.1 Solution with a mass concentration of rhodium of 2 mg/cm

The weight of rhodium with a mass of 0.2 g is weighed with an accuracy of ±0.0003 g, thoroughly mixed in an agate mortar with five times the quantity of peroxide of barium. The resulting mixture is transferred to a corundum crucible, place the crucible in a cold muffle furnace and sintered at a temperature of (850±50)°C for 2−3 h.

Crucible sintering was cooled to room temperature, transferred into sintered glass with a capacity of 250 cm, moistened with water and treated with a solution of hydrochloric acid 1:1. The beaker is heated on a stove to dissolve the cake, not bringing the solution to boiling. Cooled to room temperature, the solution was filtered through filter «blue ribbon». The filter is washed with hot hydrochloric acid 1:5.

If the dark sediment filter it is transferred to a corundum crucible with the filter, dried in air, placed the crucible in a cold muffle furnace, include heating and calcined at a temperature of (750±50)°C for 30−40 min. the Cooled residue was triturated with 1.0 g of peroxide of barium, is sintered, dissolved, filtered as described above.

The filtrates are United, evaporated to a volume of 20−30 cm, dilute with water to volume of 50 cm, heated to boiling and precipitated barium sulfate in hot sulfuric acid 1:9. After 2−3 hours check the completeness of the precipitation of barium sulfate, adding a few drops of sulfuric acid 1:9. The solution was filtered through filter «blue ribbon», or double filter «white ribbon» in a volumetric flask with a capacity of 100 cm, for washing the precipitate on the filter with hot hydrochloric acid 1:5, then 5−6 times with hot water. The volume of the solution was adjusted to the mark with hydrochloric acid 1:5 and stirred.

8.1.2 Solutions with mass concentrations of platinum, palladium, gold, antimony, misaka, selenium, tellurium, cadmium, and tin 2 mg/cm

A portion of each metal with a mass of 0.2 g is weighed with an accuracy of ±0.0003 g, and dissolved by heating the glass in a mixture of hydrochloric and nitric acids 3:1. The solutions were evaporated to a volume of 2−3 cm, add 20 cmof a hydrochloric acid solution of 1:5, cooled and transferred to volumetric flasks with a capacity of 100 cmeach, the volume was adjusted to the mark with the same acid solution and stirred.

8.1.3 Solutions with mass concentrations of iron, copper, cobalt, manganese, bismuth, Nickel 2 mg/cm

A portion of each metal with a mass of 0.2 g is weighed with an accuracy of ±0.0003 g, was dissolved with heating in a glass 10 cmof nitric acid solution 1:1. The solutions were evaporated to a volume of 2−3 cm, add 20 cmof a hydrochloric acid solution of 1:5, transferred to a volumetric flask with a capacity of 100 cm, the volume was adjusted to the mark with the same acid solution and stirred.

8.1.4 the Solution with a mass concentration of lead of 2 mg/cm

A portion of lead with a mass of 0.2 g is weighed with an accuracy of ±0.0003 grams and dissolved in a glass 10 cmof nitric acid solution 1:1 under heating. The solution is heated to remove oxides of nitrogen (stop the release of brown fumes), not boiling. Cool, transferred to volumetric flasks with a capacity of 100 cmeach, the volume was adjusted to the mark with water and mix.

8.1.5 Solutions with the mass concentrations of aluminium, chromium, magnesium and zinc 2 mg/cm

A portion of each metal with a mass of 0.2 g is weighed with an accuracy of ±0.0003 grams and dissolved in a glass 10 cmof hydrochloric acid 1:1 when heated, not boiling. The solutions were cooled, transferred to volumetric flasks with a capacity of 100 cmeach and the volume was adjusted to the mark with hydrochloric acid 1:5 and stirred.

8.1.6 the Solution with a mass concentration of titanium of 2 mg/cm

A portion of the titanium mass 0.2 g is weighed with an accuracy of ±0.0003 grams and dissolved in 20 cmof a hydrochloric acid solution 1:1 when heated in a glass, closed the watch glass, not boiling. The hydrochloric acid solution is added in portions of 5 cmuntil complete dissolution of titanium. The solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, the volume was adjusted to the mark with hydrochloric acid 1:5 and stirred.

8.2 Preparation of intermediate solutions

8.2.1 Solution A. In a volumetric flask with a capacity of 100 cmis placed 5 cmsingle-element basic solutions containing 2 mg/cmof bismuth, iron, gold, cobalt, copper, Nickel, palladium, platinum, rhodium, lead, antimony and zinc. The volume of the solution was adjusted to the mark with hydrochloric acid 1:5 and stirred.

The mass concentration of each of the elements in the solution is of 100.0 µg/cm.

8.2.2 Solution B. In a volumetric flask with a capacity of 100 cmis placed 10 cmsolution A. the Volume of the solution was adjusted to the mark with hydrochloric acid 1:5 and stirred.

Mass concentration of each of these elements in solution is 10.00 µg/cm.

8.2.3 Solution A1. In a volumetric flask with a capacity of 100 cmis placed 5 cmsingle-element basic solutions containing 2 mg/cmof aluminium, cadmium, magnesium, manganese, arsenic, tin, selenium, tellurium, titanium and chromium.

The volume of the solution was adjusted to the mark with hydrochloric acid 1:5 and stirred.

The mass concentration of each of the elements in the solution is of 100.0 µg/cm.

8.2.4 Solution B1. In a volumetric flask with a capacity of 100 cmis placed 10 cmsolution A1. The volume was adjusted to the mark with hydrochloric acid 1:5 and stirred.

Mass concentration of each of these elements in solution is 10.00 µg/cm.

8.2.5 Intermediate solutions are stable for one month at a mass element concentration of 100.0 µg/cmand for five days at a mass concentration of elements of 10.00 µg/cm.

On the containers of solutions must be pasted label with the indication of the name or symbols of elements mass concentration of elements and limit of absolute error of its establishment, date of preparation and shelf life of the solution.

8.3 preparation of the calibration samples

To determine the calibration characteristics of the calibration samples used are the solutions of the mass concentration of the determined elements to 5.0 ág/cm.

8.3.1 Calibration samples for flame atomization

In a volumetric flask with a capacity of 25 cmeach pipette taken aliquote of the intermediate solutions A, A1 or B, B1 (table 3), adjusted to the mark with hydrochloric acid 1:5 and stirred. As the background solution using a solution of hydrochloric acid 1:5.


Table 3 — Calibration samples

8.3.2 Calibration samples for atomization in a graphite atomizer

8.3.2.1 Solutions with the mass concentrations of aluminium, bismuth, arsenic, tin, platinum, selenium, lead, antimony, titanium, and tellurium 0,2; 0,4; 0,6; 1,0 µg/cm

Four sample high purity silver weight of 0.5 g each are weighed with an accuracy of ±0.0003 g, each placed in a beaker with a capacity of 250 cm, add 10 cmof hydrochloric acid 1:1 and boiled for 5−10 min. the Solutions were poured, the sample was washed with water 6−7 times by decantation. Add 10 cmof nitric acid solution 1:1 and dissolve under low heat. The glasses are administered 1,0; 2,0; 3,0 and 5,0 cmsolutions B and B1, add hot water to a volume of 150 cm, add 2 cmof hydrochloric acid and then preparation solutions are on 8.5. The solutions were placed in volumetric flasks with a capacity of 50 cmeach.

8.3.2.2 Solutions with the mass concentrations of the identified elements 0,1; 0,2; 0,3; 0,5 µg/cm

In a volumetric flask with a capacity of 25 cmeach are placed at 5 cmby solutions 8.3.2.1, add 5 cmof a solution of tartaric acid in the determination of antimony, or 5 cmof a hydrochloric acid solution 1:20 in the determination of aluminium, bismuth, arsenic, tin, platinum, selenium, lead, titanium, and tellurium and mixed. To label arguments.

8.3.2.3 Solutions with the mass concentrations of the identified elements of 0.01; 0.02; 0.03 and 0.05 mg/cm

A pipette is taken at 2.5 cmsolutions with the mass concentrations of the elements 0,1; 0,2; 0,3 and 0,5 µg/cmprepared according to 8.3.2.2, placed in a volumetric flask with a capacity of 25 cmeach, adjusted to the mark with hydrochloric acid 1:7 and stirred.

8.3.3 Calibration samples prepared on the day of use and stored for not more than two days. On the containers of solutions must be pasted label with the indication of the name or symbols of elements mass concentration of elements and limit of absolute error of its establishment, date of preparation and shelf life of the solution.

The use of other methods of preparation of solutions, subject to obtaining the metrological characteristics are not inferior to those in table 2.

8.4 Preparation of the graphite tube atomizer

Processing of graphite tubes and platforms niobium oxide is carried out as follows: the graphite tube and platform immersed in a water slurry of niobium oxide, allowed to stand for 2−3 hours, removed and dried in a drying Cabinet for 1 h at a temperature of from 100 °C to 110 °C. Then the tubes with platforms subjected to a heat treatment in a graphite atomizer: dry for 60 s at 100 °C, anneal for 30 s at 1000 °C and 10 s at a temperature of 2650 °C in an inert gas stream. The heat treatment cycle is repeated at least three times.

Processing of graphite tubes with a solution of sodium volframovich performed as follows: a graphite tube immersed in a solution of sodium volframovich and leave for 10−12 hours, then dried in a drying Cabinet for 3−4 h Before analysis tube is fired in a graphite atomizer: dry 60 s at 100 °C, anneal 30 s at a temperature of 400 °C, slowly heated for 90 s to a temperature of 2200 °C and kept at this temperature for 10 s. the Cycle is repeated at least three times.

8.5 sample Preparation

8.5.1 Two hanging silver weight (0,2−2,5) g is weighed with an accuracy of ±0.0003 g (table 4), each of which is placed in a beaker with a capacity of 250 cm, is added at 10−20 cmof a hydrochloric acid solution of 1:1 and boiled for 5−10 min. the Solutions were poured, the sample was washed with water 6−7 times by decantation.


Table 4 — Dependence of the mass of sample and the content of impurities

To the suspension was added 10 cmof nitric acid solution 1:1 and dissolve under low heat until complete dissolution of the sample. Add 5 cmof hydrochloric acid dissolve gold and rhodium under low heat for 3−5 min. Then add hot water to a volume of 100−150 cmand immediately filtered in a glass with a capacity of 250 cmthrough filter «blue ribbon», washed 4−5 times with hot hydrochloric acid solution of 1:100 and 2−3 times with hot water, without transferring the precipitate of silver chloride on the filter. The precipitate is washed by decantation 5−6 times a hot solution of hydrochloric acid 1:100. The resulting solution (filtrate 1) is evaporated to a volume of 2−3 cm.

8.5.2 Filter placed in the glass to precipitate silver chloride, add 10 cmsulphuric and nitric acids, kept at room temperature until the cessation of the violent reaction is then heated to release dense fumes of sulphuric anhydride. The glass moved to the front of the plate, gently on the side of a glass and add 4−5 drops of nitric acid and again heat to release dense fumes of sulphuric anhydride. The operation of adding nitric acid is repeated until complete dissolution of silver chloride. The solution is evaporated to wet salts, cool, add 10 cmof nitric acid, 50−100 cmof hot water and heated to dissolve the salts. Added to a solution of 3 cmof hydrochloric acid and immediately filtered into the beaker with the filtrate 1 through filter «blue ribbon», washed, as specified in 8.5.1. The precipitate is washed by decantation 5−6 times a hot solution of hydrochloric acid 1:100. The resulting solution is evaporated to a volume of 2−3 cm.

8.5.3 reduced To the solution add 3 cmof hydrochloric acid, the solution transferred to a volumetric flask with a capacity of 25 or 50 cm, adjusted to the mark with water and mix.

The resulting solution was supplied for analysis.

At the same time through all stages of sample preparation carried out two test experience on the purity of the reagents.

8.5.4 Determination of iron, gold, cobalt, copper, arsenic, Nickel, platinum, tellurium and zinc may be performed without perioadele silver chloride from the filtrate 1 after dilution of the solution, as specified in 8.5.3.

8.6 Preparation of the spectrometer to work

Atomic absorption spectrometer prepared to work according to the operating documents of the device.

9 analysis

9.1 Analysis with atomization of the sample in the flame

For the determination of bismuth, iron, gold, cadmium, cobalt, magnesium, manganese, copper, arsenic, Nickel, palladium, platinum, rhodium, lead, selenium, antimony, tellurium, zinc, use the flame of propane-butane-air or acetylene-air; for the determination of chromium using flame acetylene-air (restorative flame, the enriched combustible gas).

In the determination of rhodium and platinum in solutions injected buffer solution of sulphate of cadmium in the flask with a capacity of 25 cmis placed 5 cmof the analyzed solution or the calibration sample, add 5 cmof buffer solution and stirred.

The sequence of atomization in the flame of a gas burner calibration samples, solutions, control the experience and solutions of analyzed samples is carried out in accordance with the software of the spectrometer.

The wavelengths of the analytical lines given in table 5.


Table 5 — wavelengths of the analytical lines

The use of other analytical lines subject to receipt of the accuracy rate that rivals those in table 2.

The calibration characteristics is obtained using the calibration samples prepared according to 8.3.1. For the calibration characteristics, find the mass concentration of the element in the analyzed solution.

If the absorption values for the test portion exceeds the value of absorption corresponding to the linear section of the calibration characteristics, the sample solution was diluted with hydrochloric acid 1:7.

9.2 Analysis with atomization of the sample in a graphite atomizer

For the determination of bismuth, arsenic, platinum, lead, selenium, antimony and tellurium when the content is less than 0.005%, and aluminum, tin and titanium in the whole range of the designated contents used in atomization of samples in a graphite atomizer (cell). Sequence analysis procedures in accordance with software of the spectrometer. The conditions of atomization in a graphite atomizer HGA-74 are given in table 6.


Table 6 — Conditions of atomization in a graphite atomizer

The use of other modes subject to receipt of the accuracy rate that rivals those in table 2.

The calibration characteristics is obtained using the calibration samples prepared according to 8.3.2. For the calibration characteristics, find the mass concentration of the element in the analyzed solution.

If the absorption value for the sample analyzed exceeds the value of absorption corresponding to the linear section of the calibration characteristics, the sample solution is diluted. For dilution of the sample solution in the determination of bismuth, arsenic, tin, platinum, selenium, lead, antimony, tellurium, and titanium using a solution of hydrochloric acid 1:20. In determining the aluminium solution is diluted with water.

10 assessment of the admissibility of the results of parallel measurements and obtaining the final result of the analysis

10.1 Mass fraction of the element in % is calculated by the formula

, (2)

where is the value of the mass concentration of the analyzed element in the sample solution, obtained by the calibration feature, µg/cm;

 — the arithmetic mean value of two results of parallel measurements of the mass concentration of element in solution in the reference experiment, µ g/cm;

 — the volume of analyzed sample solution, cm;

 — the dilution factor of the analyzed solution;

 — the weight of the portion of the sample,

10.2 acceptance of the results of parallel measurements is estimated according to GOST R ISO 5725−6 by comparing the absolute discrepancy of the two results of parallel measurements with a limit value of the frequency of occurrence given in table 2.

If not exceed , two parallel definitions recognize acceptable and for the final result of the analysis is to take their arithmetic mean value.

If exceeds , then spend another two parallel definitions. If the range of the four results of the parallel definition (a) does not exceed the critical range for the 4, , the final result of the analysis taking the arithmetic mean of the four results of parallel measurements.

The critical range is calculated by the formula

, (3)

where the 3.6 — the ratio of the critical range for four parallel measurements;

 — standard deviation of repeatability, the values of which are given in table 2.

If the range of the four results of parallel measurements exceeds , the final result of the analysis taking the median of four results of parallel measurements.

11 presentation of results of analysis (measurements)

The result of the analysis (measurements) are in the form:

, 0,95,

where  — mass fraction of the element, %;

 — the boundary of the interval of the absolute error of determining the mass fraction of element in of 0.95%. The values given in table 2.

This numerical value analysis result is rounded up to discharge, which recorded the last significant digit errors in accordance with table 2.

12 Control of accuracy of analysis results

12.1 Control of intermediate precision and reproducibility

When monitoring intermediate precision (variable factors of the operator and time) is the absolute value of the difference between two results of analysis of the same sample obtained by different operators using the same equipment on different days, should not exceed the limit of intermediate precision specified in table 2.

Under the control of the reproducibility of the absolute value of the difference of the two results of the analysis of the same samples obtained by two laboratories in accordance with the requirements of this standard must not exceed the limit of reproducibility shown in table 2.

12.2 verification of correct

The checking is carried out by the analysis of samples for monitoring (QA) and control samples.

When checking the absolute value of the difference between the analysis result and the reference value of the mass fraction of element-impurities in the sample for the control or control sample should not exceed the critical value .

The critical value is calculated by the formula

, (4)

where  — error of the reference value of the mass fraction of element-impurities in the sample for the control or control sample, %;

 — the indicator of the accuracy of the analysis result corresponding to the reference value of the mass fraction of element-impurities in OK or control sample, %. The values given in table 2.

Bibliography