GOST 19251.1-79

• gost-192511-79.pdf (194.12 KiB)
  ГОСТ 19251.1-79

GOST 19251.1−79 (ISO 714−75, ISO 1055−75) Zinc. Methods for determination of iron (with Amendments No. 1, 2, 3)

GOST 19251.1−79
(ISO 714−75, ISO 1055−75)

Group B59

STATE STANDARD OF THE USSR

ZINC

Method for determination of iron

Zinc.
Method of iron determination

AXTU 1709

Date of introduction 1980−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

DEVELOPERS

V. I. Lysenko, L. I. Maksay, R. D. Cohen, V. A. Kolesnikov, N. Romanenko, R. A. Pestova

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 09.08.79 N 3077

3. Change No. 3 adopted by the Interstate Council for standardization, Metrology and certification (Protocol № 7 from 26.04.95)

The adoption voted:

4. The standard fully conforms to the ISO standards 714−75, ISO 1055−75

5. INSTEAD 19251.1 GOST-73

6. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

7. Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

8. REPRINT (February 1998) with Amendments No. 1, 2, 3, approved in October 1984, April 1989, June 1996 (ICS 1−85, 7−89, 9−96)


This standard specifies the photometric (with a mass fraction of iron from 0.001 to 0.2%) method for determination of iron.

The standard fully conforms to the ISO standards and ISO 714−75 1055−75.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis and security requirements — according to GOST 19251.0.

(Changed edition, Rev. N 1).

2. PHOTOMETRIC METHOD FOR DETERMINATION OF IRON

2.1. The essence of the method

The method is based on the ability of iron ions to form in the ammonia environment with sulfosalicylic acid complex compound, the yellow color of which photometered in the region of wavelengths 413−425 nm.

The sensitivity of the method was 20 µg in a volume of 100 cm.

2.2. Apparatus, reagents and solutions

Spectrophotometer or photoelectrocolorimeter of any kind for measurements in the visible region of the spectrum.

Nitric acid according to GOST 4461, diluted 1:1, 1:9.

Hydrochloric acid according to GOST 3118 and diluted 1:1.

Sulfosalicylic acid according to GOST 4478, a solution of 200 g/DM.

Ammonia water according to GOST 3760 and diluted 1:1 and 2:100.

Hydrogen peroxide according to GOST 10929.

Lanthanum nitrate (La (NO)·6HO) solution of 1 mg/cm: 0,3115 g of salt are dissolved in 20 cmof water with the addition of a few drops of nitric acid, the solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Potassium-sodium vinocity according to GOST 5845, solution 20 g/DM.

Iron powder restored brand MLB-1 according to GOST 9849.

Iron (III) oxide.

Standard solutions of iron.

Solution a: 0,1000 g of iron powder or 0,1300 g of iron oxide (III) is dissolved in 20 cmof nitric acid, diluted 1:1, boil to remove oxides of nitrogen. Cooled, transferred to a volumetric flask with a capacity of 1 DMand topped to the mark with nitric acid, diluted 1:9.

1 cmof solution A contains 0.1 mg of iron.

Allowed the preparation of a standard solution by dissolving the sample in hydrochloric acid.

Solution B: 50 cmsolution And placed in a volumetric flask with a capacity of 100 cmand then filled to the mark with nitric acid, diluted 1:9.

1 cmof the solution contains 0.05 mg of iron.

Solution B is prepared on the day of use.

Cadmium brand Кд00 according to GOST 22860.

(Changed edition, Rev.

N 2, 3).

2.3. Analysis

2.3.1. When the mass fraction of copper to 0.05% the weight of zinc weight of 2,5000 g is placed in a conical flask with a capacity of 250 cm, dissolved in 20 cmof nitric acid, diluted 1:1, flow 30 cmof water and boil to remove oxides of nitrogen.

Depending on the mass fraction of iron for analysis taking the entire solution or aliquot part of it after dilution with water in accordance with table.1, is placed in a volumetric flask with a capacity of 100 cm, add 5 cmof the solution Vinokurova potassium-sodium, 10 cmsulfosalicylic acid solution, neutralized with ammonia to produce yellow coloring, made up to the mark with ammonia diluted 1:1, and stirred.

Table 1

Note. Allowed dissolution of the sample with hydrochloric acid and hydrogen peroxide.


The optical density of solutions measured in the appropriate cell in the region of wavelengths 413−425 nm.

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

The iron content is set according to the calibration schedule.

2.3.2. When the mass fraction of copper in excess of 0.05% of the weight of zinc weight of 2,5000 g is placed in a conical flask with a capacity of 250 cm, dissolved in 20 cmof nitric acid, diluted 1:1 and continue to boil to remove oxides of nitrogen. The volume was adjusted with water to 70 cm, add 2 cmof a solution of lanthanum nitrate, heated to 60−70 °C and poured 12−13 cmof ammonia for the transfer of the zinc ammonium complex.

After 30 min the precipitate of hydroxides was filtered through a medium density filter and washed several times with warm ammonia solution, dilute 2:100. The precipitate is washed from the filter with hot water into a flask in which to carry out the deposition, the remnants of the filter cake and the residue in the flask is dissolved in 10 cmof hot hydrochloric acid, diluted 1:1. The filter is washed several times with hot water. The solution is evaporated to a volume of 2−3 cmand cooled.

Depending on the mass fraction of iron for analysis taking the entire solution or aliquot part of it after dilution with water in accordance with table.1, is placed in a volumetric flask with a capacity of 100 cm, add 5 cmof the solution Vinokurova potassium-sodium and further analysis is carried out as specified in clause 2.3

.1.

2.3.1, 2.3.2. (Changed edition, Rev. N 2, 3).

2.3.2. It is possible to eliminate the influence of copper recovery metal cadmium. The weight of zinc weight of 2,5000 g is placed in a conical flask with a capacity of 250 cm, is dissolved in 25 cmof hydrochloric acid 1:1, add 0.25 cmof hydrogen peroxide and boiled to remove the excess of hydrogen peroxide. Add 0.5 g of cadmium and gently heated for 3 min, shaking frequently, until full recovery of copper.

Cooled, filtered through loose paper filter, quantitatively collecting the solution and washings in a volumetric flask with a capacity of 100 cm. Dilute to the mark with water and mix.

Aliquot part of the solution is placed in a volumetric flask with a capacity of 100 cmand below, p.2.3.1.

(Added, Rev. N 2).

2.3.3. To build a calibration curve in six of the seven volumetric flasks with a capacity of 100 cmmeasured to 0,5; 1,0; 2,0; 3,0; 4,0 and 5,0 cmstandard solution B, which corresponds to 25, 50, 100, 150, 200 and 250 mcg of iron. In each flask pour 5 cmof the solution Vinokurova potassium-sodium, 10 cmsulfosalicylic acid solution and further analysis is carried out as specified in clause 2.3.1.

The optical density of solutions measured in the corresponding cell in the region of wavelengths 413−425 nm.

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

According to the obtained values of optical densities and their corresponding weight fractions of iron to build the calibration graph.

2.4. Processing of the results

2.4.1. Mass fraction of iron (), %, is calculated by the formula

,

where is the mass of iron in the solution was found in the calibration schedule, mcg;

 — the weight of the portion contained in the selected part of the solution,

2.4.2. The absolute values of the differences between the results of two parallel measurements (rate of convergence) and the results of the two tests (index of reproducibility) with the confidence coefficient =0.95 does not exceed values of allowable differences specified in table.2.

Table 2

(Changed edition, Rev. N 2).

Section 3. (Deleted, Rev. N 3).