GOST 1293.4-83

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  ГОСТ 1293.4-83

GOST 1293.4−83 lead-antimony Alloys. Methods for determination of arsenic (with Amendments No. 1, 2)

GOST 1293.4−83*
______________________
* The designation of the standard.
Changed the wording, Rev. N 2.

Group B59

STATE STANDARD OF THE USSR

LEAD-ANTIMONY ALLOYS

Methods for determination of arsenic

Lead-antimony alloys. Methods for the determination of arsenic

AXTU 1709*
________________

* Changed the wording, Rev. N 1.

Valid from 01.07.83
prior to 01.07.88*
_______________________________
* Expiration removed by Protocol No. 7−95
The interstate Council for standardization,
Metrology and certification (I & C N 11, 1995). -
Note the manufacturer’s database.

DEVELOPED by the Ministry of nonferrous metallurgy of the USSR

PERFORMERS

A. P. Sychev, M. G. Sun, L. I. Maksay, R. D. Kogan

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 of February 8, 1983 N 704

REPLACE GOST 1293.4−74

MADE: the Change in N 1, approved and put into effect by the Decree of the USSR State Committee for standards from 20.11.87 N 4205 from 01.07.88, Change No. 2 adopted by the Interstate Council for standardization, Metrology and certification (minutes N 13 dated 28.05.98). The state developer of Kazakhstan. By the resolution of Gosstandart of Russia from 11.04.2001 N 173-St introduced on the territory of the Russian Federation from 01.01.2002

Change N 1, 2 made by the manufacturer of the database in the text IUS N 2, 1988, ICS # 7, 2001

This standard sets the photometric method for the determination of arsenic at mass fraction of arsenic from 0.001 to 0.1%, and titrimetric — when the mass fraction of arsenic from 0.1 to 1% of lead-antimony alloys.

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 1293.0−83.

2. PHOTOMETRIC METHOD

2.1. The essence of the method

The method is based on dissolving the alloy in nitric acid, the formation of arsenic-molybdenum acid, the extraction of a mixture of butyl alcohol and ether, recovering the organic phase dichloride tin to molybdenum blue and subsequent measurement of the optical density of the blue the organic solution at a wavelength of 840 or 660 nm in spectrophotometer or in a region of wavelength 630−660 nm on a photoelectrocolorimeter.

(Changed edition, Rev. N 1).

2.2. Equipment and reagents

Photoelectrocolorimeter or spectrophotometer.

Hydrochloric acid by the GOST 3118−77 and 1 and 1.5 M solutions.

Nitric acid GOST 4461−77 and 5 M solution.

Ammonia water according to GOST 3760−79.

Sodium hydroxide according to GOST 4328−77, a solution of 20 g/DM, stored in a plastic container.

Ammonium molybdate according to GOST 3765−78, a solution of 15 g/DM, stored in a plastic container.

Tin dichloride a solution of 0.5 g/DMin 1 M hydrochloric acid solution, freshly prepared.

Sodium sulphate anhydrous according to GOST 6053−77.

Potassium branovitsky according to GOST 4457−74, (CRSC)=0.05 mol/DM.

Methyl orange, solution 20 g/DM.

Mixture for extraction: secondary butyl alcohol and ethyl ether acetic acid according to GOST 22300−76 in the ratio 2:1.

Arsenious anhydride according to GOST 1973−77.

(Changed edition, Rev. N 1, 2).

2.3. Preparation for assay

2.3.1. Preparation of standard solutions of arsenic

Solution a: 0,1320 g of arsenious anhydride are dissolved in 20 cmof sodium hydroxide solution. The solution is transferred into a measuring flask with volume capacity of 1000 cmand establish a pH of 5−6 with hydrochloric acid. Bring to the mark with water and mix.

1 cmof solution A contains 0.1 mg of arsenic.

Solution B: to 20 cmof the solution And pour 5 cmof hydrochloric acid and one drop of methyl orange solution, is heated to a temperature of 60−70 °C, add dropwise a solution of potassium polnovatogo until the disappearance of the pink color of the indicator. The solution was transferred to a volumetric flask with a capacity of 500 cm, was cooled to room temperature, adjusted to the mark of 1.5 M hydrochloric acid solution and stirred.

1 cmof a solution contains 0.004 mg of arsenic.

(Changed edition, Rev. N 2)

.

2.3.2. To build a calibration curve in seven separating funnels with a capacity of 100 cmeach poured in 10 cm1.5 M hydrochloric acid solution. Then six of them measure 1, 2, 3, 5, 6 and 7 cmstandard solution B. In the seventh funnel solution B is added. Add in all the craters up to 20 cm1.5 M hydrochloric acid solution, 10 cmof molybdenic acid ammonium solution and leave for 10 minutes Then added to 10 cmof the mixture for extraction and the solutions stirred for 2 min. repeat Extraction with the same amount of mixture.

Both extract collected in a separate separating funnel with a capacity of 100 cm, washed with two times 10 cmto 1 M hydrochloric acid solution. To the organic phase add 10 cmof a solution of tin dichloride and shake the funnel several times. After separation the lower layer is discarded and top layer of blue color is transferred to a volumetric flask with a capacity of 25 cm. The separating funnel was washed 2−3 times with the mixture for extraction and attach the wash mixture to the extract. Add 0.5 g of sodium sulfate, the solution was adjusted to the mark with the mixture for extraction and mixed. After 15 min measure the optical density of the solution at a wavelength of 840 or 660 nm in spectrophotometer or in a region of wavelength 630−660 nm on a photoelectrocolorimeter. Solution comparison is the solution not containing a standard solution of arsenic.

According to the obtained values of optical density and corresponding concentration of arsenic build the calibration graph.

(Changed edition, Rev. N

1).

2.4. Analysis

Depending on the expected mass fraction of arsenic take the weight of the alloy and dissolve it in nitric acid solution in accordance with the table.1.

Table 1

The solution is heated to remove oxides of nitrogen and neutralized with ammonia to form a precipitate of hydroxides. Add drop by drop nitric acid to dissolve the residue, add 12 cmof hydrochloric acid, cooled and transferred to a volumetric flask with a capacity of 100 cm. The solution was diluted to the mark with water, mixed and filtered through dense dry filter into a dry beaker.

Select aliquot part of the solution (see table.1) and transferred to a separatory funnel with a capacity of 100 cm. The volume was adjusted to 20 cm1.5 M solution of hydrochloric acid, add 10 cmof molybdenic acid ammonium solution and leave for 10 min. Poured 10 cmof the mixture for extraction, and then do as mentioned in paragraph 2.3.2.

Solution comparison in the measurement of optical density is the solution of the reference experiment.

The mass of arsenic found by the calibration schedule.

(Changed edition, Rev. N 2).

2.5. Processing of the results

2.5.1. Mass fraction of arsenic () in percent is calculated by the formula

,

where is the mass of arsenic in the analyzed solution, found by calibration schedule, mcg;

 — volume of initial solution alloy, cm;

 — weight alloy, g;

 — volume aliquote part of the solution, cm.

2.5.2. The discrepancy between the results of parallel measurements (the difference between the largest and smallest results of parallel measurements) and the discrepancy between the results of the analysis (the difference between the larger and the smaller of the results of the analysis) at a confidence level =0.95 does not exceed the permissible values of absolute differences are given in table.2.

Table 2

The control accuracy of the analysis is carried out using standard samples or by other methods stipulated by GOST 1293.0−83.

The error analysis results (at a confidence probability =0,95) does not exceed the limit values given in table.2, if the following conditions are true: the discrepancy between the results of parallel measurements does not exceed the permissible, the results of accuracy control positive.

(Changed edition, Rev. N 2).

3. TITRIMETRIC-IODOMETRIC (KHROMATOGRAFICHESKII) METHOD

3.1. The essence of the method

The method is based on the recovery of arsenic phosphonoacetate sodium, oxidation with a solution of iodine or potassium dichromate and titration of excess iodine with a solution of chernovetskogo sodium, and potassium dichromate with a solution of salt Mora.

3.2. Reagents and solutions

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

Sulfuric acid GOST 4204−77 and diluted 1:1 and 1:49.

Potassium dichromate according to GOST 4220−75, solution (KCrO)=0.05 mol/DM.

Chernovetskiy sodium (sodium thiosulfate) according to GOST 27068−86, solution (NaSO·5HO)=0.05 mol/DM.

Iodine GOST 4159−79, solution (J)=0.05 mol/DM.

Potassium iodide according to GOST 4232−74, a solution of 150 g/DM.

Sodium posterolaterally (hipofosfit sodium) according to GOST 200−76.

Sodium carbonate 10-water according to GOST 84−76.

Salt of protoxide of iron and ammonium double sulfate (salt Mora) according to GOST 4208−72, a solution with a mass concentration of 0.05 mol/DM.

The soluble starch according to GOST 10163−76, a solution of 5 g/DM, freshly prepared.

Acid N-phenylanthranilic (on-anilinophenol acid; diphenylamine-o-carboxylic acid) indicator, 1 g/DM.

Antimony GOST 1089−82 not below grade Su00.

(Changed edition, Rev. N 1, 2).

3.3. Preparation for assay

3.3.1. Preparation of potassium dichromate solution 0.05 mol/DM

Prepare fiksanala or 2,4516 g dried to constant weight at 140 °With potassium dichromate, and placed in a measuring flask with volume capacity of 1000 cm, dissolved in water, diluted to the mark with water and mix.

The titer of the potassium dichromate solution 0.05 mol/DM, expressed in grams of arsenic equal to 0,00075.

(Changed edition, Rev. N 1).

3.3.2. Preparation of 0.05 n solution of sodium thiosulfate

12.5 g of sodium thiosulfate dissolved in water, add 0.1 g sodium carbonate, diluted to 1000 cmand mix; cook for 8−10 days before use.

3.3.3. Setting the molar concentration of sodium thiosulfate

10 cmof potassium dichromate solution 0.05 mol/DM, measured by a pipette or burette, place in a conical flask with a capacity of 250 cm, a flow of 35−40 cmwater and 15 cmof hydrochloric acid (1:1), 10 cmof a solution of potassium iodide, cover the flask with glass and leave in dark place for 1−2 min. Wash walls with water, dilute with water to 100 cmand titrate the liberated iodine with the prepared sodium thiosulfate to a light yellow color of the solution. Then pour 3 cmof a solution of starch and continue titration until the disappearance of blue color.

The molar concentration of sodium thiosulfate (a) is calculated according to the formula

,

where is the molar concentration of the solution of potassium dichromate;

 — the volume of potassium dichromate solution taken for titration, cm;

 — the volume of sodium thiosulfate consumed for the titration of potassium dichromate, cm.

(Changed edition, Rev. N 1).

3.3.4. Preparation of iodine solution 0.05 mol/DM

Prepare fiksanala or 6,3452 g of iodine and 100 g potassium iodide was placed in a volumetric flask with a capacity of 1000 cm, add 3−5 cmof water and thoroughly shaken until complete dissolution of iodine, and then diluted to the mark with water and mix; store in a flask made of dark glass.

(Changed edition, Rev. N 1).

3.3.5. The installation of the mass concentration of iodine solution 0.05 mol/DM

10 cmof iodine solution, measured by pipette or burette was placed in a conical flask with a capacity of 250 cm, 60−70 cm pourwater and mix gently, titrated previously prepared solution of sodium thiosulfate until a light yellow color of the solution. Then pour 3 cmof a solution of starch and continue titration until the disappearance of blue color.

The mass concentration of iodine solution 0.05 mol/DM(), expressed in grams of arsenic, calculated as follows:

,

where is the molar concentration of sodium thiosulfate;

14,98 — molar equivalent of arsenic;

 — the volume of sodium thiosulfate consumed in the titration of iodine cm.

(Changed edition, Rev. N 1, 2).

3.3.6. Preparation of salt solution Mora 0.05 mol/DM

To 19.6 g of Mohr salt dissolved in a sulfuric acid solution (1:49), diluted with the same solution to 1000 cmand mixed.

(Changed edition, Rev. N 1).

3.3.7. Preparation of the solution phenylantranilic acid

0.1 g of sodium carbonate dissolved in 30 cmof water is added 0.1 g phenylanthranilic acid, stirred until complete dissolution and dilute with water to 100 cm.

3.3.8. Coefficient setting normality of salt solution Mora 0.05 mol/DM

10 cmof potassium dichromate solution, measured by pipette or burette was placed in a conical flask with a capacity of 250 cm, pour the 50−60 cmwater, 5 cmof sulfuric acid solution (1:1), 4−5 drops of the indicator phenylanthranilic acid and titrated with a solution of salt Mora to change the color of the solution from pink to green.

The factor of normality is calculated by the formula

,

where  — the volume of salt solution Mora, used for titration, sm.

(Changed edition, Rev. N 1).

3.4. Analysis

A portion of the alloy weight 1,0000 g is placed in a conical flask with a capacity of 500 cm, flow 75 cmof sulfuric acid, cover with watch glass and heated until complete dissolution of the sample. Cooled, poured 150 cmof water and boil for 5−6 min. the Solution was cooled, filtered through a filter medium to low density tampon of filtrowanie mass and washed 7−8 times with a solution of sulfuric acid. The precipitate of lead sulphate is discarded.

To the filtrate add 100 cmof hydrochloric acid, about 5 g of sodium phosphonoacetate, close the flask with a funnel with a short spout and leave it for 15−20 min without heating. Then heated and slightly boil for 5−10 min until complete precipitation of the arsenic. The solution was cooled and filtered through a filter filtrowanie compacted ground, or through a swab from filtrowanie mass. The precipitate is washed with cold water 8−10 times.

The precipitate of arsenic with the filter placed in a flask with a glass stopper with a capacity of 500 cm, flow 20 cm. solution of iodine. Mix thoroughly and leave for 20 min to dissolve the arsenic, then the excess of iodine titrated. a solution of sodium thiosulfate until a light yellow color. Add 3 cm ofstarch solution and continue the titration till the bleaching solution, and then add another 1 cmof sodium thiosulfate is in excess. An excess of sodium thiosulfate octarepeat solution of iodine until the first appearance of blue color.

In the case of oxidation of arsenic with a solution of potassium dichromate a precipitate with the filter is placed in a flask in which to carry out the deposition of arsenic, pour 5 cmof sulphuric acid (1:1), 10 cmof water and dissolved in an excess of solution of potassium dichromate, measured with a burette. The contents of the flask is lightly shaken until complete dissolution of arsenic (disappearance of dark particles). Add 4−5 drops of indicator phenylantranilic octarepeat acid and excess of potassium dichromate with Mohr salt solution until the color of the solution from pink to green. For a more distinct transition of color at the end of the titration add 2−3 drops of the indicator.

(Changed edition, Rev. N 1, 2).

3.5. Processing of the results

3.5.1. Mass fraction of arsenic () in percent is calculated by the formula

,

where is the volume of iodine solution (potassium dichromate) consumed for the dissolution of arsenic, cm;

 — the volume of sodium thiosulfate (salt Mora), consumed for titration of the excess iodine (potassium dichromate), cm;

 — correction factor the concentration of sodium thiosulfate (salt Mora);

 — mass concentration of iodine solution (potassium dichromate), expressed in grams of arsenic;

 — the weight of the portion of alloy,

(Changed edition, Rev. N 1, 2)

.

3.5.2. The discrepancy between the results of parallel measurements (the difference between the largest and smallest results of parallel measurements) and the discrepancy between the results of the analysis (the difference between the larger and the smaller of the results of the analysis) at a confidence level =0.95 does not exceed the permissible values of absolute differences are given in table.3.

Table 3

The control accuracy of the analysis is carried out using standard samples or by other methods stipulated by GOST 1293.0−83.

The error analysis results (at a confidence probability =0,95) does not exceed the limit values given in table.3, when the following conditions are true: the discrepancy between the results of parallel measurements does not exceed the permissible, the results of accuracy control positive.

(Changed edition, Rev. N 2).

4. TITRATION-POTENTIOMETRIC METHOD

4.1. The essence of the method

The method is based on titration of arsenic branovacki potassium potentiometric or visual indicator methyl orange after the separation of arsenic from interfering impurities transport in the form of trichloride, in the presence of hydrazine and potassium bromide.

4.2. Apparatus, reagents and solutions

pH meter-millivolt types, pH 341, pH 121 or other types.

Electromagnetic stirrer types MM-3, MM-01 or other types.

The measuring electrode is platinum.

The auxiliary electrode — saturated calomel, silver-chloride or mercuriality any brand. Measuring and auxiliary electrodes connected to a pH meter according to the instructions supplied with the device.

Installation for the distillation of arsenic trichloride (see drawing).

Installation for the distillation of arsenic trichloride

1 — boiling flask with a capacity of 500 cm; 2 — dropping funnel; 3 — nozzle with droplet separator;
4 — water refrigerator; 5 — receiver (conical flask with a capacity of 250 cm); 6 — glass tube
with a pear-shaped extension; 7 — control receiver (conical flask with a capacity of 250 cm)

Hydrochloric acid by the GOST 3118−77 and diluted 2:1 and 1:9.

Sulfuric acid according to GOST 4204−77.

Bromine according to GOST 4109−79 saturated aqueous solution (bromine water).

Potassium bromide according to GOST 4160−74.

Hydrazine sulfate according to GOST 5841−74 or hydrazine hydrochloride according to GOST 22159−76.

Potassium branovitsky according to GOST 4457−74, solution (CRSC)=0,02 mol/DM.

Methyl orange (pair-диметиламиноазобензолсульфокислый sodium), a solution of 1 g/DM.

(Changed edition, Rev. N 1, 2).

4.3. Preparation for assay

4.3.1. Preparation of the solution polnovatogo potassium 0.02 mol/DM:

0,5567 g of salt is placed in a measuring flask with volume capacity of 1000 cm, is dissolved in 150−200 cmof water, dilute to the mark with water and mix.

(Changed edition, Rev. N 1).

4.3.1. The installation of the mass concentration of the solution polnovatogo potassium.

The mass concentration of a solution of potassium polnovatogo set antimony and recalculated to the mass concentration of arsenic.

A portion of the antimony by weight 0,0200 g is placed in a conical flask with a capacity of 250 cm, add 20 cmof sulphuric acid and heated until dissolved. Cooled, diluted with water and transferred into a flask with a capacity of 500 cm, flow 20 cmof hydrochloric acid, dilute with water to 200 cmand boil for 10−15 min Cool to 60 °C, add 2−3 drops methyl orange and titrate with a solution of potassium polnovatogo (CRSC)=0,02 mol/luntil the disappearance of the red color.

The mass concentration of a solution of potassium bromoperoxidase () for arsenic in grams per cubic centimeter is calculated by the formula

,

where  — the weight of antimony, g;

the volume of the solution polnovatogo potassium consumed in the titration, cm;

0,6156 — conversion factor equal to the ratio of the atomic weight of arsenic to the atomic weight of antimony.

(Added, Rev. N 2).

4.3.2. The preparation of bromine water:

Bromine dropwise with continuous stirring added to the water before the appearance of undissolved drops on the bottom of the flask.

4.4. Analysis

A portion of the alloy weight of 2,0000 g is placed in a conical flask with a capacity of 250 cm, 30 cm, pouredsulfuric acid, covered by glass and heated until complete dissolution of the sample. Cool, cautiously along the wall of the flask pour 100 cmof water 5 cmof bromine water and boil to remove excess bromine. The solution is cooled slightly and transferred to a distillation flask with a capacity of 500 cm, using a hydrochloric acid (1:9). To the solution, the volume of which is 140−150 cm, add 1−2 g of hydrazine, 1 g of potassium bromide and attach the flask to the apparatus for distillation. The receiver and control receiver pre-pour 50−60 cmof water. Through the funnel into the distillation flask pour 200 cmof hydrochloric acid. The solution in a distillation flask heated to boiling, and carried out the distillation of trichloride arsenic until until peregonets half of the liquid. Then through the funnel into the distillation flask pour 100 cmof hydrochloric acid and continue the distillation until Athanasia 100 cmof the liquid. After the distillation the distillate and the solution of the control flask quantitatively transferred to a beaker with a capacity of 600 cm, heated to 60−70 °C, lower electrodes and the arsenic is titrated with a solution of potassium polnovatogo to jump in the potential.

By visual titration of the distillate and the solution of the control flask quantitatively transferred into a flask with a capacity of 500 cm, is heated to 70−80 °C, add 2−3 drops of methyl orange solution and titrate the arsenic with a solution of potassium polnovatogo to the disappearance of pink color. By the end of the titration are slowly vigorously stirring the solution.

(Changed edition, Rev. N 1, 2).

4.5. Processing of the results

4.5.1. Mass fraction of arsenic () in percent is calculated by the formula

,

where  — volume of the solution polnovatogo potassium consumed in the titration, cm;

the titer of a solution of potassium Bromeliaceae, expressed in grams of arsenic equal to 0,0007492;

 — the weight of the portion of alloy,

(Changed edition, Rev. N 1).

4.5.2. The discrepancy between the results of parallel measurements (the difference between the largest and smallest results of parallel measurements) and the discrepancy between the results of the analysis (the difference between the larger and the smaller of the results of the analysis) at a confidence level =0.95 does not exceed the permissible values of absolute differences are given in table.3.

The control accuracy of the analysis is carried out using standard samples or by other methods stipulated by GOST 1293.0−83.

The error analysis results (at a confidence probability =0,95) does not exceed the limit values given in table.3, when the following conditions are true: the discrepancy between the results of parallel measurements does not exceed the permissible, the results of accuracy control positive.

(Changed edition, Rev. N 2).