GOST 25278.17-87

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  ГОСТ 25278.17-87

GOST 8775.1−87 Li. Methods for determining lithium

GOST 8775.1−87

Group B59

STATE STANDARD OF THE USSR

LI

Methods for determining lithium

Lithium.
Methods for determination of lithium

AXTU 1709

Valid from 01.07.88
to 01.07.93*
__________________________
* Limit of validity
based on a Protocol of Intergovernmental
Council for standardization, Metrology
and certification (I & C N 2, 1993). -
Note the manufacturer’s database.

INFORMATION DATA

1. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 28.09.87 N 3764

2. The term of the first test 1991

The frequency of inspection 5 years

3. REPLACE GOST 8775−75 (sect.2)

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard establishes titrimetric (mass fraction of lithium when to 99.8%) and calculated (at a mass fraction of lithium of 99.8% or more) methods for the determination of lithium in lithium.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 8775.0−87.

2. TITRIMETRIC METHOD

2.1. The essence of the method

The method is based on dissolving lithium in water and titration of the lithium hydroxide with the acid solution in the presence of the indicator methyl orange.

2.2. Apparatus, materials and reagents

Box with organic glass type 6БП-1-OS or similar.

The air, prepared according to claim 2.3.1 or otherwise, to ensure moisture content not more than 0.2 g/m.

Plate of stainless steel according to GOST 5632−72 brand 40X13, 12X18H10T or other materials that are not corrosive when interacting with alkalis.

Scalpels and knives medical GOST 21240−77* or stainless steel according to GOST 5632−72.
______________
* Standards 21240−89. — Note the manufacturer’s database.

Tweezers according to GOST 21241−77.

Gauze GOST 11109−74*.
______________
* On the territory of the Russian Federation GOST 11109−90. — Note the manufacturer’s database.


Cotton calico GOST 11680−76.

Medical absorbent cotton wool GOST 5556−81.

Mineral wool GOST 4640−84*.
______________
* On the territory of the Russian Federation GOST 4640−93. — Note the manufacturer’s database.

Rubber tube GOST 7852−76 N of 7.5.

The drying oven of the type SNOL.

Laboratory scales according to GOST 24104−80, of the 2nd accuracy class with the largest weighing limit of 200 g.

Burette capacity 50 cm, of the 2nd accuracy class according to GOST 20292−74*.
________________
* On the territory of the Russian Federation there are 29169−91 GOST, GOST 29227−91−29229−91 GOST, GOST 29251−91-GOST 29253−91. Here and hereinafter. — Note the manufacturer’s database.

The conical flask with a capacity of 250 and 500 cm.

A pipette with a capacity of 50 cm, of the 2nd accuracy class according to GOST 20292−74.

Volumetric flasks with a capacity of 500 cm, of the 2nd accuracy class according to GOST 1770−74.

Cups for weighing type SV 24/10.

Funnel for filtering with a cropped end.

Hydrochloric acid by the GOST 3118−77, h. e. a., a solution of 1 mol/DM, preparation and establishment of the amendments carried out according to GOST 25794.1−83. To establish amendments of hydrochloric acid is allowed to use the state standard sample of soda ash technical notes 2404−82.

The indicator methyl orange 0,1% solution, prepared according to GOST 4919.1−77.

Distilled water GOST 6709−72, not containing carbon dioxide, prepared and stored according to GOST 4517−75.

Magnesium rate (angeren).

Of phosphorus pentoxide.

Silica gel according to GOST 3956−76.

The synthetic zeolite (molecular sieve), dried at 350 °C for 4−5 h.

2.3. Preparation for assay

2.3.1. Air preparation

The air-dried, passing through a column filled sequentially by angerona, powder phosphoric anhydride, applied to dried at a temperature of 130−150 °With silica gel, then through a column filled with zeolite. The use of other substances absorbing moisture and acids. For retention of solid particles using a glass tube filled with cotton or mineral wool.

2.3.2. A sample of lithium in the Bank, prepared according to GOST 8774−75, placed in the chamber. Take a pair of tweezers and a piece of lithium removed from the surface of the oil with a cloth, then placed it on a stainless steel plate and clean by trimming with a knife a thin layer. Cleaned chunk cut into small pieces and transfer them to another plate. Each piece is cut with a scalpel again, paying attention to the inadmissibility on the surface of the piece of yellow spots, the presence of which is evaluated visually.

2.4. Analysis

2.4.1. Prepared pieces with a total mass of 2−3 g are placed in pre-weighed Cup with lid. Take out the sealed Cup with lithium from the chamber and weighed with an error not exceeding the absolute value of 0.0005 g.

A portion of lithium is dissolved in 150−200 cmof water in the conical flask with a capacity of 500 cm, covered with a funnel with a short end, each piece of the lithium introduced into the flask after dissolving the previous one. During the dissolution the flask was cooled in cold water. The resulting solution was transferred to a volumetric flask with a capacity of 500 cm, was cooled to room temperature, adjusted to the mark with water and mix.

From the solution taken aliquot part of the 50 cmin the conical flask with a capacity of 250 cm, 75−80 cm, pourwater, add 2−3 drops of methyl orange indicator and titrate with hydrochloric acid until the yellow color to orange.

2.4.2. Carrying out analysis from a sample of lithium samples weighing 0.2−0.3 g, weighed with an error not exceeding the absolute value of 0.0001 g, in a test tube with a capacity of 1−2 cm, tightly closed with a rubber stopper.

The tube with the linkage after removing the tube is placed in a conical flask with a capacity of 250 cm, dissolve a portion of 100−120 cmof water, add 2−3 drops of indicator and titrate according to claim 2.4.1.

2.5. Processing of the results

2.5.1. Mass fraction of lithium (a) percentage calculated by the formula

,

where  — the volume of 1 mol/DMsolution of hydrochloric acid consumed for titration, cm;

 — the total volume of the analyzed solution, cm;

the amount of lithium corresponding to 1 cmexactly 1 mol/DMhydrochloric acid solution, g;

 — amendment 1 mol/DMhydrochloric acid solution;

 — aliquota part of the solution taken for titration, cm;

 — the weight of the portion of lithium found by weighing, g;

 — amendment to the charge weight of lithium based on the difference of the densities of lithium and brass weights;

 — mass fraction of sodium, %;

 — the ratio of sodium to lithium;

 — mass fraction of potassium, %;

 — the ratio of potassium to lithium;

 — mass fraction of magnesium, %;

 — the ratio of magnesium to lithium;

 — mass fraction of calcium, %;

 — the ratio of calcium to lithium;

 — mass fraction of barium, %;

 — coefficient paresce

the barium to lithium.

2.5.2. Determination of the mass fraction of sodium, potassium, calcium is carried out according to GOST 8775.2−87, the mass fraction of magnesium and barium according to GOST 8775.3−87.

2.5.3. The analysis according to claim 2.4.2 values and the formula doesn’t include.

2.5.4. The content of impurities of sodium, potassium, magnesium, calcium, barium take into account for the mass concentration of them over 0.002%.

2.5.5. The analysis result should be the arithmetic mean of two parallel definitions (unit definitions), under the conditions of the PP.2.5, 2.6, 2.10 GOST 8775.0−87.

2.6. Accuracy metrics analysis:

the relative standard deviation of repeatability of the results of parallel measurements () is not more than 0.0005;

the relative standard deviation of reproducibility of single definitions () not more than 0.001;

limits non-excluded systematic error () is not more than 0.2%.

Note. When applying for the establishment of amendments of the hydrochloric acid solution of the state standard sample of the composition of technical calcined soda GSO 2404−82 value is insignificant compared to the random error.


The value of error analysis result () not more than 0,24%.

2.7. The control accuracy of the analysis

Accuracy control is performed by varying the mass of the batches in accordance with GOST 8775.0−87, with the establishment of the amendment of hydrochloric acid solution (1 mol/DM) used GEO 2404−82.

3. CALCULATION METHOD

3.1. Mass fraction of lithium (a) percentage calculated by the formula

,

where the sum of the results of the analysis in determining in lithium, sodium, potassium, calcium (GOST 8775.2−87), magnesium, manganese, iron, aluminum, silicon, and barium (GOST 8775.3−87), nitrogen (GOST 8775.4−87), %;

 — the maximum amount of undetectable impurities, %.

3.2. The error analysis result (a) not more than 0.02%.

Non-excluded systematic error () is insignificant compared to the random error.