GOST 16274.4-77

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  ГОСТ 16274.4-77

GOST 16274.4−77 Bismuth. Method for determination of lead (with Amendments No. 1, 2, 3)

GOST 16274.4−77

Group B59

STATE STANDARD OF THE USSR

BISMUTH

Method for determination of lead content

Bismuth.
Method for determination of lead content

AXTU 1709

Date of introduction 1978−01−01

INFORMATION DATA

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

DEVELOPERS

PS Poklonsky, F. M. Manji, G. V. Khabarova

2. APPROVED AND promulgated by the DECREE of the State Committee of standards of Ministerial Council of the USSR from 25.01.77 N 172

3. The frequency of inspection 5 years

4. REPLACE GOST 16274.4−70

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Resolution of the state standard from 30.07.92 N 836 removed the limitation of the validity period

7. REPRINT (July 1997) with Amendments 1, 2, 3, approved in January 1983, June 1987, July 1992 (IUS 5−83, 11−87, 10−92)


This standard applies to metallic bismuth brands Vi1 and Vi2 and sets the polarographic method for the determination of lead (with lead content of 0.2 to 3%).

The method is based on the ability of the lead to recover on a mercury drop cathode at a potential of minus 0.45 V (relative to the bottom of mercury or saturated calomel electrode) on the background of the hydrochloric acid solution.

Deformity large quantities of bismuth are separated by cementation on iron.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 16274.0

2. APPARATUS, REAGENTS AND SOLUTIONS

Polarograph polarograph oscilloscope or AC of any type.

Volumetric flasks with a capacity of 1,000, 250, 100 cmaccording to GOST 1770.

Pipettes with a capacity of 10 and 15 cmat the NTD.

Burette with a capacity of 25 cmin the NTD.

Glasses chemical resistant according to GOST 7851.

Nitric acid according to GOST 4461, diluted 1:1 and 1:2.

Hydrochloric acid according to GOST 3118, diluted 1:2.

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

The brand Vi00 bismuth GOST 10928.

Lead of C1 grade according to GOST 3778*.
_____________
* On the territory of the Russian Federation GOST 3778−98. — Note the manufacturer’s database.

Standard solution of lead; prepared as follows: 1 g of lead dissolved in nitric acid, diluted 1:2, then evaporated to a volume of 1−2 cm, pour 5 cmof concentrated hydrochloric acid and evaporated almost to dryness. This operation is repeated 2−3 times, then pour the 200−300 cmof hydrochloric acid, diluted 1:2, and after dissolution of the precipitate the solution was transferred into a measuring flask with volume capacity of 1000 cmand topped to the mark with hydrochloric acid (1:2). The walls of the flask is washed with hydrochloric acid diluted 1:2.

1 cmof the solution contains 1 mg lead.

Calibration solutions of lead: in five volumetric flasks with a capacity of 100 cmis placed 0,5; 1,0; 2,0; 4,0 and 6,0 cmstandard solution of lead and topped to the mark with a standard solution of bismuth.

1 cmof the calibration solutions contain respectively 5, 10, 20, 40 and 60 micrograms of lead.

A standard solution of bismuth; prepared as follows: 2 g of bismuth dissolved in 20 cmof nitric acid, diluted 1:1. The solution was evaporated almost to dryness, poured 10 cmof hydrochloric acid and again evaporated to obtain a wet salts. This operation is repeated 2−3 times. Then pour the 200−300 cmof hydrochloric acid, diluted 1:2, and after dissolution, the salt solution is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with hydrochloric acid diluted 1:2 and stirred.

1 cmof solution contains 2 mg of bismuth.

Mercury GOST 4658.

(Changed edition, Rev. N 2, 3).

3. ANALYSIS

A sample of bismuth with a mass of 0.2 g is dissolved in 5 cmof nitric acid, diluted 1:1, and evaporated almost to dryness. Pour 5 cmof concentrated hydrochloric acid and again evaporated to dryness. This operation is repeated 2−3 times. Then pour 40−50 cmof hydrochloric acid, diluted 1:2. After the solids are dissolved, the solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with hydrochloric acid diluted 1:2 and thoroughly mixed. In the dry Cup stand 20−25 cmsolution and add in small portions 1 g of the recovered hydrogen to iron.

10−15 min after full recovery of bismuth polarographic lead at potentials from minus 0.4 to minus 0.6 V.

In these circumstances, polarographic calibration and control solutions.

To calculate the results of the analysis using calibration solutions of similar wave height to be tested.

(Changed edition, Rev. N 2).

4. PROCESSING OF THE RESULTS

4.1. Lead content () in percent is calculated by the formula

,

where the wave height of test solution, mm;

 — wave height of the calibration solution;

 — the concentration of the calibration solution of lead, µg/cm;

 — hitch, g;

 — the total volume of solution, cm;

1000000 — conversion factor for grams to micrograms

.

4.2. The maximum discrepancy between the results of three parallel measurements () and the results of two tests () at a confidence probability of 0.95, should not exceed the values given in the table.

Permitted discrepancies for the intermediate mass fraction calculated using linear interpolation or according to the formulas:

for the range of mass fraction from 0.2 to 1.0%;

for the interval St. a mass fraction of 1.0 to 2.0%;

for a mass fraction of more than 2.0%;

where is the arithmetic mean of results of three parallel measurements;

 — the arithmetic mean of the results of the two tests.

4.1, 4.2. (Changed edition, Rev. N 3).