GOST 21877.8-76

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  ГОСТ 21877.8-76

GOST 21877.8−76 Babbit tin and lead. Methods for determination of zinc (with Amendments No. 1, 2)

GOST 21877.8−76

Group B59

STATE STANDARD OF THE USSR

BABBIT TIN AND LEAD

Methods for determination of zinc

Tin and lead babbits. Methods for the determination of zinc*

AXTU 1709**
_______________
* The name of the standard. Changed the wording, Rev. N 2.
** Added, Rev. N 2.

Valid from 01.01.78
to 01.01.83*
______________________________
* Expiration removed
according to the Protocol of the Intergovernmental Council
for standardization, Metrology
and certification (I & C N 2, 1993). -
Note the manufacturer’s database.

DEVELOPED by the Central research Institute for tin industry (Tsniiolovo)

Director V. A. Arsenico

Supervisor S. V. Meshkov

Executor G. V. Ivanova

INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

Zam. Minister N.N. Chepelenko

The draft all-Union scientific research Institute of standardization (VNIIS)

Director A. V. Gichev

APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from may 24, 1976 N 1264

REPLACE GOST 1380.10−70

MADE: the Change in N 1, approved and put into effect by the Decree of the USSR State Committee for standards from 14.02.83 N 805 with 01.07.83, Change N 2 approved and entered in gastbeoordelingen of the USSR State Committee for standards from 25.06.87 N 2463 with 01.03.88

Change N 1, 2 made by the manufacturer of the database in the text N 6 ICS 1983 ICS N 10 1987


This standard applies to tin and lead babbits and sets photocolorimetric and spectral methods for determination of zinc content (with zinc content of 0.001 to 0.15%) and atomic absorption.

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 21877.0−76.

2. PHOTOCOLORIMETRIC METHOD FOR DETERMINATION OF ZINC

2.1. The essence of the method

The sample is decomposed in a mixture of hydrochloric acid and bromine. Tin and antimony is distilled off in the form of chlorides, zinc isoamylase remove alcohol from hydrochloric acid solution, and after transfer to the aqueous phase is determined by photocolorimetry colored complex with dithizone in carbon tetrachloride at a wavelength of 540 nm.

2.2. Apparatus, reagents and solutions

Photoelectrocolorimeter or spectrophotometer with all accessories.

Separating funnels, with a capacity of 100, 150, and 700 cm.

Hydrochloric acid by the GOST 3118−77 and diluted 1:10.

Sulfuric acid GOST 4204−77, diluted 1:1.

Bromine according to GOST 4109−79.

Ammonia according to GOST 3760−79.

Ammonium radamisty, a solution of 400 g/DM. The solution is purified from impurities by extraction with alcohol isoamylase: 500 cmsolution is shaken out with 25 cmisoamyl alcohol for 2 min.

The washing liquid; is prepared as follows: to 300 cmof water is poured 100cm40% purified solution Rodenstock ammonium and 2.5 cmof sulfuric acid solution, diluted 1:1.

Ammonium chloride according to GOST 3773−72, a solution of 200 g/DM. Solution clean ditizona, which 100 cmof solution is shaken with a solution of dithizone 0.05 g/DMportions at 2−3 cmuntil until no longer changes the color of dithizone. Then the rest of dithizone is extracted from the solution with carbon tetrachloride until then, until a new portion of it will remain colorless.

Ammonia solution ammonium chloride: to 200 cmof water is poured 20 cmof 20% aqueous purified solution of ammonium chloride and 25 cmof ammonia solution.

Isoamyl alcohol according to GOST 5830−79.

Alizarin red S (sodium alizarinsulfonate), a solution of 1 g/DM, indicator.

Acetic acid GOST 61−75, solution of concentration of 4 mol/DM; prepared as follows: 240 cmacid is poured into a measuring flask with a capacity of 1 DM, adjusted to the mark with water and mix.

Sodium acetate according to GOST 199−78, solution 1 mol/l; prepared as follows: was 60.05 g sodium acetate dissolved in water, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.

Acetate buffer solution: prepared by mixing equal parts of solution concentration of 4 mol/DMacetic acid, solution 1 mol/DMsodium acetate (pH 4).

Chernovetskiy sodium (sodium thiosulfate) according to GOST 244−76, a solution of 500 g/DM, purified ditizona the same way as ammonium chloride.

Carbon tetrachloride according to GOST 20288−74.

Ditson (diphenylthiourea) according to GOST 10165−79, a solution of 0.5 g/DM: prepared by dissolving 50 mg of reagent in 50 cmof carbon tetrachloride. The solution was transferred to a separatory funnel and shaken twice with 100 cmof solution ammonia concentration of 20 g/DM, and then the organic layer discarded. The aqueous layer is slightly acidified with concentrated hydrochloric acid, add 50 cmof carbon tetrachloride and shake. After separation of the carbon tetrachloride extraction is repeated with a new portion of carbon tetrachloride. Both extract were combined and washed with water. Solution dithizone stored in a dark bottle with a glass stopper.

Solution dithizone 0.05 g/DM; prepare a dilute solution of carbon tetrachloride concentration of 0.5 g/DM10 times.

Zinc GOST 3640−79*, brand or color C1.
________________
* Valid GOST 3640−94, here and hereafter. — Note the manufacturer’s database.

Standard solutions of zinc

Solution A, prepared as follows: 0.5 g of zinc metal are dissolved in 10 cmof hydrochloric acid diluted 1:1, transferred to a volumetric flask with a capacity of 500 cm, was adjusted to the mark with water and mix.

1 cmof solution A contains 1.0 mg of zinc.

Solution B is prepared by diluting with water the solution A 100 times a day application.

1 cmof a solution contains 0.01 mg of zinc.

(Changed edition, Rev. N 1, 2).

2.3. Analysis

2.3.1. A portion of the babbit weighing 0.5 g were placed in a glass with a capacity of 100 cm, pour the 7 cmof concentrated hydrochloric acid, 1−1. 5 cmof bromine, cover with a watch glass and allowed to stand without heating to dissolve the sample. Then remove the glass, wash with 2−3 cmof hydrochloric acid and a moderate heat evaporate the solution to dryness. The dry residue is treated again with 5 cmof concentrated hydrochloric acid and again evaporated to dryness. To the dry residue poured 20 cmof hydrochloric acid, diluted 1:10 and heated to boiling. The solution was cooled, transferred to a volumetric flask with a capacity of 50 cm, adjusted to the mark with hydrochloric acid diluted 1:10, and stirred. After settling from the clear solution pipetted aliquot part of the solution and transferred to a separatory funnel with a capacity of 150 cm.

Value aliquote part depending on the content of zinc in the sample are shown in table.1.

Table 1

Further, in a separating funnel flow 20 cm40% strength solution of ammonium Rodenstock, 1 cmof sulfuric acid diluted 1:1, and 10 cmisoamylalcohol alcohol. The funnel is stoppered and vigorously shaken for 2 min. After the separation of the liquids, the aqueous layer discarded. To an alcoholic solution poured into the funnel 20 cmwash liquid, and shake the funnel for 1 min. the Aqueous layer again discarded. The washing procedure is repeated three more times. Next to the organic phase poured 15 cmammonia ammonium chloride solution, shaken for 15 s and after separation of the liquid drained ammiaka zinc into another separatory funnel with a capacity of 100 cm. Stripping 15 cmof ammonia solution of ammonium chloride again.

Ammonia solutions are combined, add in the funnel two drops of the alizarin red indicator, acetate buffer solution to pH 5−6 (the solution becomes yellow-pink color) and 1 cmof sodium thiosulfate.

The extracted solution of 0.005% solution of dithizone in carbon tetrachloride in portions of 2−3 cm. As the extraction of zinc from aqueous solution the color of the extract changes from red through purple to green. Extraction is done when a new piece of dithizone will not change its color. The extracts decanted into a volumetric flask with a capacity of 50 cmwith a glass tube, topped up to the mark with carbon tetrachloride, stirred and filtered the solution through a dry ash-free filter into a dry flask, discarding first portion of filtrate.

Optical density of the solution is measured on photoelectrocolorimeter at a wavelength of 540 nm in a cuvette with a layer thickness of 1 cm as a solution of comparison used carbon tetrachloride.

(Changed edition, Rev. N

1).

2.3.2. Construction of calibration curve

In a separating funnel with a capacity of 100 cmplaced 0; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 cmstandard solution B, and poured into the funnel at 30 cmof ammonia solution of ammonium chloride, two drops of the indicator set of the acetate buffer solution of pH 5−6 and further analysis are as indicated in claim 2.3.1.

Measure the optical density of solutions after subtraction of the readings of the optical density of standard solutions of the readings of the optical density of the solution in the reference experiment to build a calibration curve.

(Changed edition, Rev. N 1).

2.4. Processing of the results

2.4.1. The zinc content () in percent is calculated by the formula

,

where the amount of zinc found in the calibration schedule g;

 — volume of initial solution, cm;

 — volume aliquote part of the solution, cm;

 — the weight of the portion of the sample,

(Changed edition, Rev. N 1).

2.4.2. Allowable absolute differences the results of the analysis shall not exceed the values specified in table.2.

Table 2

(Changed edition, Rev. N 2).

3. SPECTROCHEMICAL METHOD FOR THE DETERMINATION OF ZINC CONTENT

3.1. The essence of the method

The method is based on the translation of the sample metal oxide. The oxidized sample is mixed with carbon powder and placed in the crater, the lower carbon electrode. For the excitation spectrum uses a DC-arc. Spectrum arc is photographed with a spectrograph. Measure the blackening of analytical lines and «internal standard». Concentrations of the determined elements are found in the calibration schedule.

3.2. Apparatus, materials and reagents

Spectrograph for the registration of the ultraviolet region of the spectrum with being a lighting system or any type of spectrograph operating in the ultraviolet region, with photographic or photoelectric registration of spectrum.

A constant current source to power the arc.

A muffle furnace with thermostatic control.

Drying Cabinet.

Quartz vypaivali Cup.

The glasses are made of quartz.

Libra torsion or analytical.

Microphotometer.

Mortar agate or from glass.

Photographic plates spectrographic type 1 or ES.

Spectral-clean coals.

Bath or electric hot plate.

Developer and fixer according to GOST 10691.0−73* — GOST 10691.4−73*. Allowed the use of developer and fixer of a different composition.
_________________
* Valid GOST 10691.0−84;
** A GOST 10691.4−84.- Note the manufacturer’s database.

Copper oxide, h.d. a.

Ethyl alcohol according to GOST 5962−67.
______________
* Valid GOST R 51652−2000. — Note the manufacturer’s database.
Lead oxide according to GOST 9199−77, h.d. a.

Nitric acid GOST 4461−77, H. h, distilled.

Of antimony trioxide, h.d. a.

Zinc oxide according to GOST 10262−73, h.d. a.

Tin oxide according to GOST 22516−77, h.d. a.

(Changed edition, Rev. N 1, 2).

3.3. The preparation of calibration samples

Calibration samples are prepared identical to the content of the main components of the analyzed samples. Basis for the preparation of calibration samples is a mixture of appropriate amounts of oxides: tin, antimony, copper (babbit B88 brands, B83 and B83S), tin, antimony and lead (for grades of babbit B16, bn, and BS6).

In the parent sample containing 1% of zinc, based on the metal enter the oxide of zinc. The sample was stirred with ethanol, then dried, calcined and again thoroughly mixed.

Working samples prepared serial dilution of each of the preceding sample basis. Prepare a series of samples with zinc in them from 0.003 to 0.2%.

3.4. Medium samples are taken a sample weight of 3−5 g, which is placed in a quartz glass or Cup, pour 50−70 cmof nitric acid, diluted 1:1. The sample is dissolved with moderate heating. The solution was evaporated to dryness, and then calcined in a muffle furnace at a temperature of 500−550 °C for 20 min.

Obtained by dissolving and calcining the precipitate of metal oxides are thoroughly mixed, fill into the craters of carbon electrodes, having a size of 3x3 mm, with lateral holes 1 mm. in Front of spectroheliogram carbon electrodes, it is necessary to anneal in the arc of an alternating current power 10−12 And during 15 s At spectrographically electrodes are placed so that the lower electrode with the sample was the anode and the upper electrode, sharpened to a truncated cone with ground diameter of 1,5−2,0 mm — the cathode.

The exposure time, an intermediate aperture, slit width choose optimal for obtaining intensity spectra at normal pochernenija. Spectra excited in the arc of an alternating current power of 10 A. the time of the plate 3 min at developer temperature of 18−20 °C.

Spectra produced on the plate of type 1 or ES.

Determination of zinc are in the same sample along three parallel definitions.

(Changed edition, Rev. N 2).

3.5. Processing of the results

3.5.1. The resulting spectrograms photometric blackening of the zinc lines and lines of «internal standard».

Used analytical lines and «internal standard» are given in table.3.

Table 3

The results of electrophoretic spectra of the calibration samples to build a calibration curve in the coordinates .

The results of electrophoretic spectra of samples chart find the content of zinc. The result is then multiplied by a conversion factor of 1.2.

3.5.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in table.4.

Table 4

(Changed edition, Rev. N 2).

4. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF ZINC CONTENT

4.1. The essence of the method

The method is based on selective absorption of light from a standard source of zinc atoms. The solution is sprayed into acetylene-air flame atomic absorption spectrometer and measure the absorbance at a wavelength of 213,8 nm.

4.2. Apparatus, reagents and solutions

Spectrophotometer atomic absorption.

The glasses are made of PTFE with a capacity of 50 and 300 cm.

Nitric acid, OS.h. according to GOST 11125−78*.
______________
* Standards 11125−84. — Note the manufacturer’s database.

Hydrofluoric acid (hydrofluoric acid).

Distilled water GOST 6709−72, double-distilled.

Mix to dissolve; cook according to GOST 21877.3−76.

A mixture of chrome, a solution of potassium dichromate of concentration 100 g/lin concentrated sulfuric acid;

Zinc GOST 3640−79.

Standard solutions of zinc.

Solution A, prepared as follows: 0,1000 g of zinc is dissolved in 20 cmof nitric acid, diluted 1:1, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix. 1 cmof the solution contains 0.1 mg of zinc.

Solution B is prepared prior to use: 10 cmsolution And placed in a flask with a capacity of 100 cm, adjusted to the mark with water and mix. 1 cmof a solution contains 0.01 mg of zinc.

(Changed edition, Rev. N 2

).

4.3. Analysis

4.3.1. The dishes needed for analysis, washed successively with a mixture of chromic, hydrochloric acid, water and then at least twice washed with distilled water.

4.3.2. Depending on the amount of zinc a portion of the Babbitt weight specified in the table.5, is placed in a beaker made of PTFE with a capacity of 50 cmand poured in small portions to 10 cmof the mixture for dissolution. Further analysis is carried out according to GOST 21877.3−76.

Table 5

Fotometrirovanie is carried out at a wavelength of 213,8 nm under the conditions specified in GOST 21877.3−76.

The zinc concentration set at the calibration schedule, fotometriya simultaneously with the analyzed solutions a series of solutions with known content of zinc.

4.3.3. To build a calibration curve in a volumetric flask with a capacity of 50 cm, measure off microburette 0; 1,0; 2,0; 4,0; 10,0; 15,0; 20,0 cmstandard solution B zinc, poured at 10 cmof the mixture for dissolution, adjusted to the mark with water and mix.

Photometric as the analyzed solutions. According to the obtained average values of absorbance and known concentrations of zinc build a calibration curve.

4.4. Processing of the results

4.4.1. The zinc content () in percent is calculated by the formula

,

where is the concentration fotometricheskogo solution, µg/ml;

 — fotometricheskogo volume of solution, ml;

 — the weight of the portion of the babbit, g;

 — conversion factor from micrograms to grams.

4.4.2. Allowable absolute differences the results of the analysis at a confidence level of 0.95, should not exceed the values given in table.6.

Table 6