GOST 1367.4-83

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  ГОСТ 1367.4-83

Group B59

INTERSTATE STANDARD

ANTIMONY

GOST 1367.4−83 Instead of GOST 1367.4−76

Methods for determination of arsenic

Antimony. Methods lor the determination of arsenic AXTU 1709

Resolution of the USSR State Committee on standards of 16 December 1983, L" 6012 date of introduction is established 01.01.85

Limitation of actions taken under the Protocol .\with 4−93 inter-state Council on standarten. Metrology and certification (ICS 4−94)

This standard establishes the colorimetric method for the determination of arsenic from 2*10-⁵ to 4 I0^-4 % and a photometric method for the determination of arsenic from 0.008 to 4.0% antimony.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis and security requirements — according to GOST 1367.0−83.

2. COLORIMETRIC METHOD

The method is based on the reaction of formation of arsenic-molybdenum blue is extracted, SOA-Milov alcohol. Previously arsenic is separated from antimony and accompanying of elements (silicon, phosphorus, etc.) by extraction with carbon tetrachloride from hydrochloric acid solution.

2.1. Up parature, reagents and solutions

Quartz glasses according to GOST 19908−90 with a capacity of 50 and 100 cm'.

Beakers, glass, laboratory for GOST 25336−82 capacity I DM³.

Separating funnel with a capacity of 25 and 50 cm³.

Volumetric flasks according to GOST 1770−74 with a capacity of 100 cm³ and I DM³.

Cylinders measuring according to GOST 1770−74 with a capacity of 10 and 25 cm³.

Beakers according to GOST 1770−74 with a capacity of 100, 250 and 1000 cm'.

Pipette with divisions for NTD with a capacity of 1, 2 and 5 cm³.

Cylinder colour glass length 200 mm. with a diameter of 10 mm with ground stoppers.

Bidistilled water is prepared by distillation of distilled water in a quartz distillation apparatus.

Sulfuric acid of high purity according to GOST 14262−78. Mother 3/DM³ and 0.5 mol/DM' solutions.

Hydrochloric acid of high purity according to GOST 14261−77 and 1 mol/DM³ solution.

Ascorbic acid for NTD, a solution with a mass fraction of 0.5%.

Potassium permanganate according to GOST 20490−75, a solution with a mass fraction of 0.5% (solution replaced with a new one as soon as the precipitate of manganese dioxide).

Carbon tetrachloride according to GOST 20288−74.

Ammonium molybdate according to GOST 3765−78 perekristallizatsii, a solution with a mass fraction of 1% to 3 mol/DM⁵ solution of sulfuric acid.

Hydrazine sulfate according to GOST 5841−74. a solution with a mass fraction of 0.15%.

Sodium hydroxide according to GOST 4328−77, a solution with a mass fraction of 10%.

Potassium hydroxide according to GOST 24363−80, 1 mol/DM* solution.

Official edition Reprinting is prohibited

Edition with amendment # I, the approval." in March 1989 (IUS 6−89).

35

C. 2 GOST 1367.4−83

Isoamyl alcohol according to GOST 5830−79.

Arsenious anhydride according to GOST 1973−77.

Solutions of the arsenic standard.

Solution a: 0,132 g of arsenious anhydride were placed in a glass with a capacity of 100 cm³, pour 10 cm³ of sodium hydroxide solution. Then a solution of arsenic poured into a measuring flask with volume capacity I DM³, made up to the mark with water and mix.

I cm³ of solution contains 0.1 mg of arsenic.

Solution B: 1 cm³ solution And poured into a measuring flask with a capacity of 100 cm³, made up to the mark with water and mix, cook in day of application.

1 cm³ of a solution contains I mg of arsenic.

(Changed edition, Rev. No. 1).

2.2. Analysis

2.2.1. A portion of the antimony grades Soooo, Sooooo. Swoooop, Soooooo weighing 0.5 g is placed in a quartz glass with a capacity of 50 or 100 cm\ poured 5 cm* concentrated sulphuric acid, cover the beaker watch glass and Ragwort when heated. After dissolution, the sample is removed from the glass plate and cooled at room temperature and then in ice water. Without removing the glass from the dish with cold water, remove the watch glass, poured 15 cm³ of carbon tetrachloride and then, mix gently, pour small portions of concentrated hydrochloric acid to dissolve the sulfate (this takes approximately 3−4 cm³ of acid). The contents of the beaker poured into a separatory funnel with a capacity of 50 cm³, washing the walls of the beaker with concentrated hydrochloric acid (only used 12 cm³ of acid). Separating funnel is stoppered and extracted arsenic, vigorously shaking the funnel for 1 min. After separation of the liquid layer of carbon tetrachloride is poured into another separatory funnel with a capacity of 25 cm', and washed with 5 cm³ of hydrochloric acid, shaking the funnel for a few seconds. After 5 min, the layer of carbon tetrachloride is poured into a third separatory funnel with a capacity of 25 cm⁵ and carry out the Stripping of arsenic with 5 cm³ of water by shaking the funnel for 1 min. the Supernatant layer of carbon tetrachloride is discarded (you should follow the careful separation of the phases) and the aqueous extract is transferred to a cylinder for colorimetrically.

It is advisable the dissolution of batches of antimony and arsenic separation by extraction chetyreche-rstam carbon run in parallel on multiple samples.

After reextract water collected in the cylinders to colorimetrically they poured drop by drop potassium permanganate solution until the appearance of slightly pink color. After 5 minutes and added dropwise a freshly prepared solution of ascorbic acid to bleaching solutions. Then poured into cylinders of 0.5 cm³ of a solution of ammonium molybdate. 0.2 cm³ of hydrazine sulfate solution, stirring the contents of the cylinder after addition of each reagent.

Further, the cylinders with the solutions immersed in a glass of boiling water and allowed to stand 5 min. from the moment of boiling water. Then the cylinders are cooled, add 1 cm³ or more (depending on the arsenic content) of isoamyl alcohol, stirred for 10−15 times and compare the color of the supernatant organic layer extracts color scale comparison.

At the same time spend three control experience in the chemicals through all stages of the analysis.

2.2.2. Preparation SCSI solutions comparison

In the cylinders the same diameter;" ground stoppers pour the standard solution B in an amount corresponding 0,05; 0,10: 0.20; 0,40; 0.60; 0,80; 1,0 micrograms of arsenic, made up of double-distilled water to a volume of 5 cm³, acidified by 2−3 drops of a solution of I mol/DM³ hydrochloric acid solution, added dropwise a solution of potassium permanganate to the appearance of slightly pink color, then the ascorbic acid solution and then act as described in section 2.2.1.

The scale comparison is prepared simultaneously with the analysis of the analyzed samples.

(Changed edition, Rev. No. 1).

2.3. Processing of the results

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

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GOST 1367.4−83 C. 3

^ (t, — t₂) • 100 ' «t ■ 1000 — 1000 '

where t, is the mass of arsenic in restore of the sample, µg;

t, — the average mass of arsenic in solutions control experiments, µg: t — the weight of antimony,

2.3.2. The difference between the two results of parallel measurements and the difference of two analysis results with a confidence probability P = 0.95 does not exceed the allowable absolute differences of precision and reproducibility, are given in table. 1.

Table I

(Changed edition, Rev. No. 1).

3. PHOTOMETRIC METHOD

The method is based on Vastanicheski arsenic to the elemental state hypophosphite sodium and tin chloride and 6 mol/DM⁵ via the hydrochloric acid solution in the presence of copper as catalyst.

3.1. Apparatus, reagents and solutions

Spectrophotometer or photoelectrically. meter of any type for measuring in the visible region of the spectrum.

Beakers, glass, laboratory for GOST 25336−82 with a capacity of 1 DM³.

Flask, glass, laboratory for GOST 23932−90 with a capacity of 50 cm³.

Volumetric flasks according to GOST 1770−74 with a capacity of 25, 50 cm³ and 1 DM'.

Beakers according to GOST 1770−74 with a capacity of 100 cm³.

Pipette with divisions for NTD with a capacity of 1, 2, 5 and 10 cm³.

Funnel glass according to GOST 23932−90.

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

Hydrogen peroxide according to GOST 10929 — -76, a solution with a mass fraction of 30%.

Copper sulfate according to GOST 4165−78, a solution with a mass fraction of I % hydrochloric acid, diluted 1:1.

Sodium posterolaterally (hipofosfit sodium) according to GOST 200−76 or phosphorus-novelistically (hipofosfit calcium) on the other 6−09−6278−86, a solution with a mass fraction of 30% hydrochloric acid diluted 1:1, prepared on the day of application.

Tin dichloride on the other 6−09−5384−88, a solution with a mass fraction of 20%\ 20 g of reagent was dissolved by boiling in 50 cm³ of concentrated hydrochloric acid. The solution was cooled, poured into a beaker and made up to volume of 100 cm³ water.

Sodium hydroxide according to GOST 4328−77, a solution with a mass fraction of 10%.

Arsenious anhydride according to GOST 1973−77.

Standard solution of arsenic: 0,132 g of arsenious anhydride were placed in a glass with a capacity of 100 cm³, pour 10 cm³ of a solution of sodium pizookie. The solution is poured into a measuring flask with a capacity of 1 DM³, made up to the mark with water and mix.

1 cm³ of solution contains 0.1 mg of arsenic.

(Changed edition, Rev. No. 1).

37

C. 4 GOST 1367.4−83

3.2. Analysis

3.2.1. A portion of the antimony grades Sooo, FCS, SS 1 and SS2 with a mass of 0.1−0.5 g (see table. 2) was placed in a conical flask with a capacity of 50 cm³, cover funnel, pour 5 cm' of concentrated hydrochloric acid and heated in a boiling water bath with continuous stirring, gradually adding dropwise hydrogen peroxide to completely dissolve the sample. Then leave in water bath 5−8 min for the complete decomposition of hydrogen peroxide.

The resulting solution (in the analysis of antimony brands of Sooo. LMS) is poured into a measuring flask with a capacity of 25 cm —¹, washing the walls of the flask, which decomposed the sample, hydrochloric acid (1:1), and the volume was adjusted solution of the same acid up to 10 cm³.

Table 2

In the analysis of antimony brands of SS1 and SS2 solution was transferred to volumetric flask with a capacity of 50 cm³ and the volume was adjusted solution to the mark with hydrochloric acid (1:1). For colorimetrically taken aliquot part of the solution, equal to 2−10 cm³ (see table. 1) in a volumetric flask with a capacity of 25 cm³.

Next, in a flask with a solution of antimony pour 2 cm³ of a solution of sulphate of copper, 1 cm³ of a solution of tin dichloride and 5 cm³ of a solution of hypophosphite sodium or calcium. After adding each reagent a solution is mixed, add hydrochloric acid (1:1) to the mark and mixed again. The flask with the solution was immersed for 10 minutes in a Cup of boiling water. Then the flask is removed and cooled.

Optical density of the solution is measured at ftohte kg ro Col ori meter, applying the filter to the light transmission of about 413 nm and a cell length of 30 mm. Before you drink the solution in the cuvette must be stirred. Solution comparison is water.

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

(Changed edition, Rev. No. 1).

3.2.2. Construction of calibration curve

In six of the seven volumetric flasks with a capacity of 25 cm³ flow consistently 0,2; 0,4; 0.6; at 0.8, 1.0 and 1.2 cm³ of a standard solution of arsenic, which corresponds to 0.02: 0.04: 0,06; 0,08; 0,10 and 0,12 mg of arsenic, poured in all the bottles hydrochloric acid (1:1) up to 10 cm³, 2 cm³ of a solution of copper sulphate. 1 cm³ of a solution of dichloride of tin, 5 cm³ of hypophosphite sodium or calcium and then do as described in 3.2.1.

On the found values of optical densities and their corresponding mass fractions of arsenic build the calibration graph.

3.3. Processing of the results

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

(/I, — I»;) — -100 t ■ V_t -1000 '

where /I is the mass of arsenic, was found in the calibration schedule, mg:

t₂ is the average mass of arsenic in solutions control experiments, mg;

V is the total volume of the solution of the sample, cm³;

V — volume of aliquote part of the solution, cm³, t is the weight of antimony,

38

GOST 1367.4−83 C. 5

3.3.2. The difference between the two results of parallel measurements and the difference of two analysis results with a confidence level P — 0.95 does not exceed the allowable absolute differences of precision and reproducibility, are given in table. 3.

Table 3

39