GOST 26239.4-84

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  ГОСТ 26239.4-84

GOST 26239.4−84 DICHLOROSILANE. Methods for the determination of impurities (with Change No. 1)

GOST 26239.4−84

Group B59

STATE STANDARD OF THE USSR

DICHLOROSILANE

Methods for the determination of impurities

Dichlorsilane. Methods co impurities determination

AXTU 1709

Valid from 01.01.86
to 01.01.91*
________________________________
* Expiration removed
Protocol N 7−95 Interstate Council
for standardization, Metrology and certification
(IUS N 11, 1995). — Note the manufacturer’s database.

DEVELOPED by the Ministry of nonferrous metallurgy of the USSR

PERFORMERS

Y. A. Karpov, M. N. Schulepnikov, M. K. Vinnikov, G. G., Gavin, N. Gradskova, O. V. Zavialov, T. I. Zyablova, V. E., Quinn, V. A. Krylov, A. I. Kuzovlev, N. And. Marunya, V. G., Miscreants, V. M. Mikhailov, M. G. Nazarova, V. A. Orlov, A. I. Stepanov, N. With. Sysoeva, V. I. Firsov, G. I. Alexandrova

INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

Member Of The Board Of A. P. Snurnikov

APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on standards dated July 13, 1984 N 2490

The Change N 1, approved and in effect as of 01.01.91 by the resolution of Gosstandart of the USSR from 26.06.90 N 1847

Change No. 1 made by the manufacturer of the database in the text ICS N 10, 1990


This standard specifies two methods for determination of impurities in DICHLOROSILANE: chemical-atomic-emission method with excitation spectra arc DC and chemical-atomic-emission with excitation spectra of the discharge with a hot hollow cathode.

The intervals the determined values of mass fraction of impurities, the wavelengths of the analytical lines given in table.1.

Table 1

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 26239.0−84.

2. CHEMICAL-ATOMIC-EMISSION METHOD WITH EXCITATION SPECTRA ARC DC

______________
* The name of the section. Changed the wording, Rev. N 1.

The method is based on excitation of the DC arc spectrum concentrate of impurities obtained by Stripping base in the form of silicon tetrafluoride, photographic registration of spectra of samples of comparison and definition of mass fractions of impurities in the calibration graphs.

2.1. Apparatus, materials and reagents

The quartz type spectrograph ISP-30 single-lens lighting system.

The arc generator type DG-2, is adapted to ignite the DC arc high frequency discharge.

Rectifier 250−300, 30−50 A.

Microphotometer geregistreerde type MF-2.

Coal shaped (Fig.1).

Damn.1. The electrodes for the analysis in the arc of DC

The electrodes for the analysis in the arc of DC

Damn.1

Analytical scale.

Libra torsion.

Lamp according to GOST 13874−83*, ikz 220−250.
_____________
* On the territory of the Russian Federation the document is not valid with 01.01.79. Products discontinued (IUS N 12, 1978).

Boxing desktop 9БП-1-OS.

Mortar and pestle made of organic glass.

The PTFE cylinders with caps up to 50 cm.

Photographic plates spectrographic type II, size 9x12 cmor equivalent, providing normal darkening of the background and analytical lines in the spectrum.

Polypropylene pipettes with a capacity of 2; 5 and 10 cmof firm Cortell.

Developer and fixer are prepared according to GOST 10691.0−84.

The technical rectified ethyl alcohol GOST 18300−87.

The absorber (Fig.2).

Damn.2. Absorber

Absorber

1 — plastic Bank BTS-100; 2 — cylinder of PTFE

Damn.2

Pipettes according to GOST 20292−74* type 6−1-10; 4−1-1; 8−2-0,1.
________________
* On the territory of the Russian Federation the document is not valid. There are 29169−91 GOST, GOST 29227−91−29229−91 GOST, GOST 29251−91-GOST 29253−91. — Note the manufacturer’s database.

Hydrofluoric acid, OS.H. 27−75.

D (-) mannitol according to GOST 8321−74 optionally recrystallized.

Boric acid, OS.H. 14−3.

Nitric acid according to GOST 11125−84, OS.H. 21−5.

Deionized water grade A.

Powder graphite OS.H. 8−4 according to GOST 23463−79.

Sodium chloride, OS.H. 6−4.

Primary aluminium GOST 11069−74* grade A 99.
______________
* On the territory of the Russian Federation the document is not valid. Valid GOST 11069−2001. — Note the manufacturer’s database.

Bismuth GOST 10928−75* or brand Ви0.
______________
*On the territory of the Russian Federation the document is not valid. Valid GOST 10928−90. — Note the manufacturer’s database.

Gallium of 99.999 or higher purity.

The iron carbonyl is obtained by way of the OS.H. 6−2.

Indium GOST 10297−75* brand Ин2 or higher purity.
______________
*On the territory of the Russian Federation the document is not valid. Standards 10297−94. — Note the manufacturer’s database.

Magnesium primary GOST 804−72* brand MG-90 or higher.
______________
*On the territory of the Russian Federation the document is not valid. Standards 804−93. — Note the manufacturer’s database.

Cobalt GOST 123−78* grade K-1 or higher.
______________
* On the territory of the Russian Federation the document is not valid. Valid GOST 123−2008. — Note the manufacturer’s database.

Manganese metal according to GOST 6008−82* brand Mr Mr 0 or 00.
______________
* On the territory of the Russian Federation the document is not valid. Valid GOST 6008−90. — Note the manufacturer’s database.

Copper GOST 859−78* not lower than grade M-1.
______________
* On the territory of the Russian Federation the document is not valid. Valid GOST 859−2001. — Note the manufacturer’s database.

Tin GOST 860−75 not below grade O1.

Nickel GOST 849−70* not below grade N-2.
______________
* On the territory of the Russian Federation the document is not valid. Deistvuet GOST 849−2008. — Note the manufacturer’s database.

Lead according to GOST 3778−77* not below grade-3.
______________
* On the territory of the Russian Federation the document is not valid. Valid GOST 3778−98. — Note the manufacturer’s database.

Silver GOST 6836−80* brand Ср999,0 or Ср999,9, or silver nitrate according to GOST 1277−75, CH.
______________
* On the territory of the Russian Federation the document is not valid. Standards 6836−2002. — Note the manufacturer’s database.

Titanium sponge according to GOST 17746−79* grade TG-90 and TG-90A.
______________
* On the territory of the Russian Federation the document is not valid. Deistvuet GOST 17746−96. — Note the manufacturer’s database.

Chrome according to GOST 5905−79* grades Х99А or А99Б.
______________
* On the territory of the Russian Federation the document is not valid. Standards 5905−2004. — Note the manufacturer’s database.

Zinc GOST 3640−79* stamps C1.
______________
* On the territory of the Russian Federation the document is not valid. Valid GOST 3640−94. — Note the manufacturer’s database.

The main solutions comparison, containing 10 mg/cmof detectable elements (aluminum, bismuth, gallium, iron, indium, cobalt, copper, magnesium, manganese, Nickel, tin, silver, lead, titanium, chromium, zinc), prepared as follows:

1 g of the metal bismuth, copper, lead, silver dissolved in the minimum quantity of nitric acid, the solutions were transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with water and mix;

1 g of the metals aluminum, gallium, iron, indium, cobalt, magnesium, manganese, Nickel, tin, titanium, chromium, zinc, dissolve in a minimum quantity of hydrochloric acid, the solutions were transferred to volumetric flasks with a capacity of 100 cm, adjusted to the mark with water and mix.

The main reference solution containing 1 mg/cmboron: 0,571 g of boric acid dissolved in a small amount of deionized water, the solution was transferred to volumetric flask with a capacity of 100 cm, adjusted to the mark with deionized water, and stirred.

A solution containing 10 mg of sodium chloride in 1 cm: 1000 mg of sodium chloride dissolved in a small amount of deionized water, the solution transferred to a volumetric flask with a capacity of 100 cm, adjusted to the mark with deionized water, and stirred.

(Changed edition, Rev. N 1).

2.2. Preparation for assay

2.2.1. A mixture of graphite powder with a mass fraction of sodium chloride of 0.5%: 9,95 g of graphite powder was placed in a mortar made of organic glass, pour 5 cmof a solution containing 10 mg of sodium chloride in 1 cmof deionized water, stirred for 15 min and dried under an infrared lamp. The mixture is then again stirred for 1.5 h and stored in Teflon cylinders with cover.

2.2.2. Prepare two series of samples comparisons based on graphite powder with a mass fraction of sodium chloride of 0.5%: a series of basic sample comparisons I OOC (for determination of aluminium, bismuth, gallium, iron, indium, cobalt, magnesium, manganese, copper, Nickel, tin, lead, silver, titanium, chromium, zinc) and a series of basic sample comparisons II OOS (to determine the boron).

The main reference sample (I EP) with a mass fraction of aluminum, iron, cobalt, magnesium, Nickel, titanium, chromium 0.1%, bismuth, gallium, indium, tin, lead 0.05%, manganese, copper, silver, 0.01% zinc and 0.4% of the: in Teflon Cup with a capacity of 100 cmis placed 9,862 g of a mixture of a graphite powder containing 0.5% of sodium chloride, poured to 1 cmhead of solutions comparison of aluminium, iron, cobalt, magnesium, Nickel, titanium, chromium, 0.5 cmhead of solutions comparison, bismuth, gallium, indium, tin, lead, 0.1 cmhead comparison of solutions of manganese, copper, silver and 4cmhead comparison of the solution of zinc (each of these solutions contains 10 mg/cmof one of the designated element).

The mixture is dried and mixed in a Cup and then in a mortar made of organic glass during 3 h. the resulting mixture was dried under an infrared lamp and placed in a Teflon cylinder with a lid.

2.2.3. The primary comparison sample II OOS with a mass fraction of boron of 0.1% in a mortar made of organic glass place of 9.49 g of a mixture of graphite powder with sodium chloride with a mass fraction of sodium chloride of 0.5%, add 0.5 g of D (-) mannitol, and 10 cmof the solution comparison of boron containing 1 mg/cmboron. The mixture was stirred for 30 min and dried under an infrared lamp. The mixture is then stirred for 3 hours, dried under an infrared lamp and placed in a Teflon cylinder with a lid for storage.

2.2.4. References to determine all impurities except boron, (OS I — OS VI) is prepared by dilution of main sample of comparison I OOS, and then each subsequent reference sample graphite powder with a mass fraction of sodium chloride of 0.5%. The mass fraction of each of the designated impurities in the samples comparison OS I — OS VI (in percent, calculated on the metal content in the mixture of metals, carbon and chloride of sodium), and added to the mixture of sample graphite powder with 0.5% sodium chloride and the sample diluted sample are given in table.2.

Table 2

2.2.5. Samples for boron determination (bare I — bare VI) is prepared by dilution of main sample comparisons II OOS, and then each subsequent sample comparison of a graphite powder with a mass fraction of sodium chloride of 0.5%. Mass fraction of boron in the bare I — bare VI (in percent, based on the boron content in the mixture of carbon, sodium chloride and boron) and added to the mixture of sample graphite powder with 0.5% sodium chloride and the sample diluted sample are given in table.3.

Table 3

2.3. Analysis

2.3.1. The concentration of impurities

Fill the sink (damn.2) for the selection of DICHLOROSILANE 30 cmhydrofluoric acid (1:1), a control absorber 50 cmof deionized water. In determining boron in a solution of hydrofluoric acid make 2 cm1% solution of mannitol. Weigh the filled sinks with an accuracy of at least 0.01 g Collect system for the selection of DICHLOROSILANE (damn.3) and purged it with argon. With the help of rotameter and pressure regulator set flow of DICHLOROSILANE, ensure absorption of 5 g of the gas within 60 min.

Damn.3. Installation diagram for the selection of analytical test portions of DICHLOROSILANE

Installation diagram for the selection of analytical test portions of DICHLOROSILANE

1 — a glass of water, temperature 15−25 °C; 2 — cylinder with DICHLOROSILANE; 3 — valve, 4 — argon for purging, excessive pressure of 0.02 kPa; 4 — pressure regulator; 5 — rotameter; 6 — absorber; 7 — controlling the absorber

Damn.3

Allowed to absorb DICHLOROSILANE without flowmeter for 60 min with a bandwidth of 25−30 bubbles per minute in the control absorber. In the sinks should not be falling out of silicon dioxide; otherwise the experience of marriage.

Weigh the absorber after absorption of DICHLOROSILANE, with polypropylene pipette transferred in Teflon cups aliquot of the solution corresponding to 0.5 g of DICHLOROSILANE in the analysis for impurities 1 g in the analysis of the boron, and removed them to 20 mg of a collector of a graphite powder with a mass fraction of sodium chloride of 0.5%. If silicon tognella not completely, then add 0.2−0.4 cmof hydrofluoric acid and repeat the evaporation. The volume of aliquots of a solution is calculated by the formula in determining all impurities except boron and according to the formula in the determination of boron,

where is the mass of the absorber (Fig.3) solution after absorption of DICHLOROSILANE, g;

 — the mass of the same absorbent solution to the absorption of DICHLOROSILANE,

To prepare the solution in the reference experiment in the absorber is placed 30 cmhydrofluoric acid 1:1 (in the case of determining boron is injected, in addition, another 2 cmof a 1% strength solution of mannitol) and incubated for the same time during which the analyses were carried out. Aliquots of this solution corresponding to the volume containing the analyzed sample of the DICHLOROSILANE, is evaporated as when carrying out analysis

.

2.3.2. Excitation and photography of the spectra on the impurity and boron

The obtained dry residue, which is a concentrate of impurities is transferred to the craters of graphite electrodes (Fig.1B), pre-annealed in the arc of direct current power 10 And for 20 C. is Placed in the craters of graphite electrodes (same type) for three parallel sample weight of 20 mg samples comparison.

The electrode with the concentration of impurities or reference sample is an anode, the upper electrode (cathode) (Fig.1A) — graphite electrode, sharpened to a cone.

Load a cassette with photographic plates of the spectral type II, set the width of the goal of spectrograph 0,016 mm and placed before the slit of a three-step attenuator. Fix the prepared electrodes in the electrode holder tripod and set between them a distance equal to 2.5 mm at the shadow projection. Evaporate the samples in the arc of DC power 12 And for 10 s.

In the same conditions photographed three times the spectra of concentrates of analyzed samples for content of impurities, or boron, control samples and samples of comparison for the determination of impurities or boron.

Exposed photographic plates show washed with water, fixed, washed with running water for 15 min and dried.

2.4. Processing of the results

2.4.1. Fix the plate on the object table microphotometry and focused image of the spectra on the screen.

Measure the maximum value of the density of the blackening of analytical lines () (see table.1) and the minimum value of the density of blackening of the nearby background ().

Find the difference pucherani () between pochernenija analytical lines and the background, and calculate the arithmetic mean value from three parallel.

From the obtained average values are transferred to corresponding values of the logarithms of relative intensity given in the mandatory Annex GOST 13637.1−77*.
______________
* On the territory of the Russian Federation GOST 13637.1−93, here and hereafter. — Note the manufacturer’s database.

Values and comparison of samples for build calibration graphs.

The calibration chart is determined by the magnitude of the mass fraction of elements in the concentrates of the analyzed samples and in the concentrate control experience

.

2.4.2. Mass fraction of impurity is defined () in percent is calculated by the formula

,

where  — mass fraction determined by the impurities in the concentrate of the sample, %;

 — mass fraction determined by the impurities in the concentrate in the reference experiment, %;

 — the ratio of concentration equals the ratio of the mass of DICHLOROSILANE (contained in the sampled aliquot) to the sample manifold.

The value should not exceed the established method for the lower boundary determined by the mass fraction of each element. Failure to comply with this condition must be carefully phased in to clean the room, jobs, used reagents and materials.

2.4.3. To control the convergence of the results of parallel measurements of the three values , , obtained three spectrograms taken for the three concentrate aliquots of the sample, select the largest and smallest values, pass them to the values and given in the Appendix GOST 13637.1−77 and find the corresponding mass fraction of impurities

.

2.4.4. The ratio of the highest of the three results of parallel measurements for the smallest with confidence probability of 0.95 does not exceed the permissible differences of the three results of parallel measurements specified in the table.4.

2.4.5. Photograph concentrates of samples analysed, control experience and comparison samples on a different plate in accordance with the PP.2.3−2.4.3.

The ratio of the greater of the two results of the analysis to less with confidence probability of 0.95, should not exceed the values permitted by the divergence of the two results, given in table.5.

2.4.6. Mass fraction of each impurity in the sample is defined as the geometric mean of the two results of the analysis of this impurity.

2.4.7. Control of the correctness analysis is carried out by additives. For this analysis one sample of the DICHLOROSILANE at PP.2.3−2.4.4 is performed twice, by introducing a second analysis in a solution of hydrofluoric acid supplements of the determined elements in the parent solutions comparison (if necessary, diluting them to the desired degree). Supplement head comparisons of solutions introduced in this volume in which the mass fraction of each designated item, calculated relative to the mass of absorbed of DICHLOROSILANE in the aliquot of the solution, calculated according to claim 2.3.1, was no less than tripled the lower bound determined by the mass fraction of this element, are given in table.4, is not less than the tripled value of the mass fraction of each element in the sample and not more than the value of the upper mass fractions given in table.4.

Table 4

The result of the analysis you think is right with confidence probability of 0.95, if the allowable discrepancy between the results of the analysis of samples with the additive and the calculated value (where the result of analysis of the sample,  — the mass fraction of additives) does not exceed the values given in table.5.

Table 5

3. CHEMICAL-ATOMIC-EMISSION METHOD WITH EXCITATION SPECTRA OF THE DISCHARGE WITH A HOT HOLLOW CATHODE

______________
* The name of the section. Changed the wording, Rev. N 1.

The method is based on excitation of a discharge with a hot hollow cathode spectra concentrates impurities, obtained after distilling off the base in the form of silicon tetrafluoride, photographic registration of spectra of samples of comparison and the determination of mass fractions of impurities in the calibration graphs.

3.1. Apparatus, materials and reagents

Apparatus, materials and reagents according to claim 2.1 with the addition of.

The rectifier 1000 V 2 A, assembled according to the scheme given on features.4, or made up of two universal power supplies, UIP-1.

Damn.4. Power installation of the hollow cathode

Power installation of the hollow cathode

PR1, PR2 — fuses 10 amp; L — neon lamp type TN-0,2−1R-69;  — resistance 10 kω, 0.5 W; 1P, 2P, 3P relay contacts ; the «start» button the power supply; «stop» — button stress relief; Latr — type autotransformer Latr-10; Tr — transformer 220/1000 V, 2 kW; D1-D4 — diodes type PVKL-100 (1000, 5);  — ballast resistance of 500 Ohms, 0.75 kW; PC — metal discharge tube with a hot hollow cathode;  — a DC voltmeter up to 500V;  — ammeter DC up to 2 A

Damn.4

The installation of the hollow cathode, consisting of inlet helium (hell.5) and a metal discharge tube with a hot hollow cathode (Fig.6).

Damn.5. System inlet helium

System inlet helium

1 — mercury manometer; 2 — vacuum valves; 3 — the trap of quartz with activated charcoal, cooled with liquid nitrogen, helium purification from impurities of molecular gases; 4 — thermocouple manometric transformer type PMT-2; 5 — metal discharge tube with a hot hollow cathode; 6 — trap with liquid nitrogen to trap the oil vapor; 7 — fore-vacuum pump type 2НВР-5 FM

Damn.5

Damn.6. Metal discharge tube with a hot hollow cathode

Metal discharge tube with a hot hollow cathode

1 — PTFE tube; 2 — water-cooled metal body; 3 — hollow cathode holder; 4 — hollow cathode; 5 — rubber gasket; 6 — quartz optical glass; 7 — clamping nut

Damn.6

Helium gas, purified, grade A before it enters the metal discharge tube with a hot hollow cathode is additionally cleaned from impurities of molecular gases in a trap with activated charcoal, cooled with liquid nitrogen.

Hollow cathodes (Fig.7), turned from coals spectral OS.H. 7−3, with a diameter of 6 mm is Manufactured, the cathodes are cleaned by placing them in the installation (DWG.5 and 6) and creating a discharge at a current of 1.2 A for 3 min with exposure of the spectrum in the last minute on a photographic plate. The system is filled with helium to atmospheric pressure and incubated for cathodes within 10 min. For the analysis of selected cathodes, in which the spectra density of blackening is used for the analysis of the analytical lines do not exceed 0.20 units logarithmic scale microphotometer for aluminum, iron, magnesium and 0.05 units of a logarithmic scale of microphotometer for bismuth, indium, gallium, cobalt, copper, manganese, Nickel, tin, silver, lead, titanium, chromium, zinc.

Damn.7. Hollow-cathode spectral coals from the OS.H. 7−3 with a diameter of 6 mm

Hollow-cathode spectral coals from the OS.H. 7−3 with a diameter of 6 mm

Damn.7

Thermocouple vacuum gauge type W-3.

The Dewar vessel of the type SK-16 according to GOST 16024−79.

The micropipette at 0.005 cm.

Hydrochloric acid according to GOST 14261−77.

Nitric acid of high purity according to GOST 11125−84, OS.H. 21−5.

PTFE Cup with a capacity of 10 cmbefore analysis is treated in a nitric acid vapor for 1 h.

The primary reference solution of silver containing 1 mg/cmof silver dissolve in low heat 100 mg of metallic silver in the 10 cmof nitric acid, diluted in the ratio 1:1. The solution was cooled, poured into a volumetric flask with a capacity of 100 cm, adjusted to the mark with deionized water, and stirred.

(Changed edition, Rev. N 1).

3.2. Preparation for assay

The main reference solution (ORS) containing aluminium, bismuth, iron, magnesium, tin, titanium, chromium, zinc 0.4 mg/cm, indium, cobalt, Nickel 0.2 mg/cm, gallium, manganese, copper, lead 0.04 mg/cmof silver and 0.004 mg/cm: in a volumetric flask with a capacity of 100 cmare placed 50 cmof concentrated hydrochloric acid, poured on a 4 cmhead of solutions of aluminium, bismuth, iron, magnesium, tin, titanium, chromium, zinc, 2 cm — head solutions India, cobalt, Nickel, lead, 0.4 cm — head of solutions of gallium, manganese, copper, silver, and adjusted to the mark with hydrochloric acid.

On the day of analysis from the LFS are preparing a series of working solutions comparison PC serial dilution of ORS, and then each subsequent PC with hydrochloric acid diluted at a ratio of 1:1, in accordance with the table.6.

Table 6

For sample preparation comparison OS take three graphite hollow cathode, pre-cleaned as described in section 3.1. At the bottom of each of them with the help of a micropipette is placed 0,005 cmPC 1 and dried to dryness under IR-lamp. Similarly receive three hollow graphite cathode with dry residues of solutions comparison of PC2-PC5. Get number of samples comparison with content mass fraction of each of the designated impurities in terms of the analyzed sample of the DICHLOROSILANE at 0.2, are given in table.7.

Table 7

3.3. Analysis

3.3.1. The concentration of impurities

The concentration of impurities of the samples and the control experiment is performed according to claim 2.3.1 with the addition of: aliquota part of the solution from the absorber, corresponding to 0.2 g of DICHLOROSILANE, the value of which is determined by the formula , is evaporated in Teflon cups dry. The obtained precipitation was dissolved in 0.1 cmof hydrochloric acid and transferred to the bottom of the graphite hollow cathode, pre-cleaned as described in section 3.1, and evaporated to dryness under the lamp ikz-220−500.

3.3.2. Excitation and photography of the spectra

Load the cassette with the photographic plate SP-2 9x12, put it in a frame of the spectrograph ISP-30 and open the damper. When photographing spectra using single-lens lighting system. Quartz lens with a focal length (75 mm) placed at a distance of 165 mm from the slit of the spectrograph and 125 mm from the open end of the hollow cathode.

In the discharge tube on the hollow cathode holder placed one empty cathode and tri cathode with parallel control samples. Pumping installation to a pressure of 2.66 PA (2 x 10mm of mercury.St.), fill it with helium to a pressure of 2.66 x 10PA (20 mm Hg.St.), connect to power supply a cathode blank, set the current of 1 A and conducted system training for 2 min.

Connected to the power source, the first cathode with the control sample, set the amperage of 0.4 A and carry out the calcination of the cathode for 2 minutes Open the slit of the spectrograph, set the current strength of 0.7 A and are shooting for 1 min for the determination of copper and silver. Move the tape to a new location, increase the current up to 1 A and a second survey for 1 min for the determination of aluminium, bismuth, gallium, iron, indium, cobalt, magnesium, manganese, Nickel, tin, lead, titanium, chromium, zinc. Similarly carry out the shooting of the second and third cathodes with the control sample.

Fill the system with air up to atmospheric pressure and hold the recharge of the discharge tube. Then repeat the operation for recording the spectra of all analyzed samples and sample comparison.

Exposed photographic exhibit, washed with water, fixed, washed with running water for 15 min and dried.

3.4. Processing of the results

Treatment results are in accordance with clause 2.4, using the analytical lines of impurity elements shown in table.1, given that the mass percent of impurities determined () percentage calculated by the formula .

Control of the correctness of the analysis carried out in accordance with paragraph 2.4.7.