GOST 12697.9-77

• gost-126979-77.pdf (548.57 KiB)
  ГОСТ 12697.9-77

GOST 12697.9−77 Aluminum. Methods for determination of zinc (with Amendments No. 1, 2, 3)

GOST 12697.9−77

Group B59

INTERSTATE STANDARD

ALUMINIUM

Methods for determination of zinc

Aluminium. Methods for determination of zinc

ISS 77.120.10
AXTU 1709

Date of introduction 1979−01−01

The decision of the State standards Committee of the Council of Ministers of the USSR from 27.09.77 N 2315 date of imposition established 01.01.79

Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

REPLACE GOST 12705−67 in part of sec. 2, 3

EDITION with Amendments No. 1, 2, 3 approved in December 1980, November 1985, may 1988 (IUS 3−81, 2−86, 8−88).


This standard specifies methods for the determination of zinc in aluminum:

photometric with niaprazine when the mass fraction from 0.003 to 0.15%;

photometric with ditizona when the mass fraction of zinc from 0,0002 to 0,003%;

— polarographic for the mass concentration of from 0.001 to 0.1%;

atomic absorption when the mass fraction of from 0.001 to 0.02%.

(Changed edition, Rev. N 1, 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 12697.1−77 and GOST 25086−87.

(Changed edition, Rev. N 2, 3).

2. The PHOTOMETRIC METHOD for the DETERMINATION of ZINC NIAPRAZINE (with a mass fraction of zinc from 0.003 to 0.15%)

2.1. The essence of the method

The method is based on formation of colored complex compounds with niaprazine, which is highly soluble in vodnosolevy environment.

Colored solution photometered in nm.

2.2. Apparatus, reagents and solutions

Types photoelectrocolorimeter FEK-56M, PEC-60, KLF or the types of spectrophotometer SF-16, SF-26, or similar type.

pH meter type pH-340 or similar type.

Laboratory scales according to GOST 24104−2001 of the 2nd accuracy class with the weighing error of 0.0002 g.
__________________
* From 1 July 2002 was put into effect GOST 24104−2001** (here and below).

** On the territory of the Russian Federation GOST R 53228−2008, here and hereafter. — Note the manufacturer’s database.

Sieves with mesh NN 016 and 0315 according to GOST 6613−86.

Column chromatographic glass.

Hydrochloric acid of high purity according to GOST 14261−77 diluted 1:1; 2 mol/land 0.005 mol/DMsolutions.

Distilled water not containing heavy metals. If necessary it is purified by passing through a layer of strongly acidic cation exchange resin (KU-1, KU-2), as specified in GOST 12697.8−77.

Sodium hydroxide according to GOST 4328−77; 0.2 mol/DMsolution. Store in a plastic container.

Indicator paper Congo.

Acetic acid GOST 61−75.

Sodium acetate according to GOST 199−78; 0.2 mol/DMsolution; the pH of this solution was set equal to 6.2 with acetic acid or sodium hydroxide.

Acetone according to GOST 2603−79.

Notafraid (N'-[1-(4-nitro-2-oksifenil)-2-naphthyl]-propionylacetate), a solution with a mass fraction is 0.028% in acetone.

Zinc GOST 3640−94.

Anion exchange resin, strong-base, type AB-17, the grain size 0,160−0,315 mm.

The resin is prepared as follows: wear the resin, sift it through a sieve N 0315, discarding the fraction with grain size 0,315 mm. more Then the rest of the resin through a sieve N 016, while the fraction with grain size less than 0,160 mm drop and collect the fraction remaining on the sieve. The selected fraction was washed by decantation 0.005 mol/DMhydrochloric acid solution. Washed fraction as long as the delivered solution will not be transparent. Then washed the resin is kept at 0.005 mol/DMhydrochloric acid for approximately 12 h

The thus-prepared resin is transferred into a ion exchange column, the bottom of which previously placed a small layer of glass wool. The height of the layer of anion exchange resin when the diameter of the grains 0,160−0,315 mm and the diameter of column 10 mm must be 100−120 mm.

The prepared column was washed with 100 cmof 0.005 mol/DMhydrochloric acid at a throughput rate of 5−7 cm/min then passed through a column of 50 cmof 2 mol/DMhydrochloric acid at a speed of 1−1,5 cm/min.

Resin in the column must be under a layer of liquid.

Solutions of the zinc standard.

Solution A, prepared as follows: 0,5000 g of zinc is dissolved in 20 cmof hydrochloric acid diluted 1:1. The solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof solution contains 0.5 mg of zinc (Zn).

Solution B is prepared before use as follows: a pipette, take 10 cmof solution A in a volumetric flask with a capacity of 1000 cm, made up to the mark with water and mix.

1 cmof a solution contains 0.005 mg of zinc (Zn).

(Amended

, Edit. N 3).

2.3. Analysis

2.3.1. A portion of the aluminum mass of 0.25−2 g depending on the assumed mass fraction of zinc is placed in a beaker with a capacity of 150−250 cm, 30−60 cm pouredhydrochloric acid diluted 1:1, covered with a glass watch glass and heated to dissolve sample. After complete dissolution of the aluminium, the glass is washed with water and the solution is evaporated prior to the deposition of salts.

To the solution was added to 17 cmof hydrochloric acid diluted 1:1, and diluted to 50 cmwater. The solution in the beaker was stirred.

Received 2 mol/DMhydrochloric acid solution is passed through an ion exchange column at a rate 1−1,5 cm/min While the chloride complex of zinc sorbed by the anion resin and the zinc is separated from interfering impurities which pass through the column, not being absorbed by.

Then, the beaker and the column was washed with three portions of 25 cmof 2 mol/DMof hydrochloric acid by passing it at a speed of 1−1,5 cm/min.

Passed through the column, the solutions are discarded.

Zinc, absorbed by the anion exchange resin, eluted with 150 cmof 0.005 mol/DMof hydrochloric acid, collecting the eluate in a glass with a capacity of 250 cm. Bandwidth acids 1−1,5 cm/min.

The obtained eluate is transferred to a volumetric flask with a capacity of 200 cm, is poured a solution of 0.005 mol/DMof hydrochloric acid to the mark and mix.

To the column was re-used following extraction of zinc, through her missing 50 cmof 2 mol/DMhydrochloric acid at a speed of 1−1,5 cm/min. the Solution was passed through the column, is discarded.

Pipetted 10 cmof test solution in a volumetric flask with a capacity of 50 cmand it is neutralized with 0.2 mol/DMsolution of sodium hydroxide, adding it drop by drop until the purple color of paper of the Congo. Then pour 10 cmof sodium acetate with a pH of 6.2 and 20 cmof acetone and pipette 1 cmof a solution of niaprazine. The solution was topped to the mark with acetone and mix.

The ratio of aqueous and acetone solutions should be 1:1,5.

Measure the optical density of the solution on the photoelectrocolorimeter or spectrophotometer, given that a maximum of light absorption of solutions corresponds to a wavelength of 646 nm. Solution comparison is water.

At the same time spend control experience. To do this in a glass pour 30 to 60 cmof hydrochloric acid diluted 1:1 (depending on how much acid is to dissolve the sample), and evaporated to approximately 17 cm, and then dilute the solution to 50 cmand further analysis is carried out as specified in clause 2.3.1.

The mass of zinc is determined according to the calibration schedule, taking into account the amendment in the reference experiment.

2.3.2. Construction of calibration curve

In a volumetric flask with a capacity of 50 cmpoured from microburette 0; 0,5; 1,0; 2,0; 3,0; 4,0 cmstandard solution B, which corresponds to 0; 0,0025; 0,005; 0,010; 0,015; 0,020 mg of zinc. Dilute up to 10 cmwith a solution of 0.005 mol/DMof hydrochloric acid and neutralized with 0.2 mol/DMsolution of sodium hydroxide, adding it drop by drop until the purple color of paper of the Congo. Further analysis is carried out as specified in clause 2.3.1.

Solution comparison is the solution, in which zinc was not added.

According to the obtained values of optical density of solutions and the known mass of zinc build a calibration curve.

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

2.4. Processing of the results

2.4.1. Mass fraction of zinc () in percent is calculated by the formula

,

where is the mass of zinc that was found in the calibration graphics mg;

 — the total volume of solution, cm;

 — volume aliquote part of the solution, cm;

the weight of aluminium,

2.4.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in table.1.

Table 1

(Changed edition, Rev. N 1, 3).

3. The PHOTOMETRIC METHOD for the DETERMINATION of ZINC DITHIZONE (with a mass fraction of zinc from 0,0002 to 0,003%)

3.1. The essence of the method

The method is based on formation of colored complex compounds of zinc with dithizone. Formed dithizonate of zinc extracted with carbon tetrachloride. The influence of interfering elements can be eliminated by use of triple extraction. Finish the definition by the method of monochrome painting, removing excess dithizone solution of sodium sulfide.

Colored solution photometered in nm.

3.2. Apparatus, reagents and solutions

Types photoelectrocolorimeter FEK-56M, PEC-60, KLF or the types of spectrophotometer SF-16, SF-26 or similar type.

A laboratory autotransformer (Latr) type Latr-1M or selenium rectifier, applying the electrodes of the Fisher.

Laboratory scales according to GOST 24104−2001 of the 2nd accuracy class with the weighing error of 0.0002 g.

Hydrochloric acid of high purity according to GOST 14261−77; 4 and 0.02 mol/DMsolutions.

Distilled water not containing heavy metals.

Distilled water is purified by passing through a layer of strongly acidic cation exchange resin (KU-1, KU-2), as specified in GOST 12697.8−77.

All reagents are prepared in purified in such way water.

Ammonia water according to GOST 3760−79, cleaned, and prepared for saturation of water with ammonia vapour, which in the desiccator, pour ammonia solution on the liner of the dryer is placed a quartz Cup containing water. After 12 h water saturated with ammonia. Ammonia concentration set titration and diluted to the desired concentration.

Sodium citrate, treasuremania, a solution with a mass fraction of 50%. The solution is purified as follows: in a separating funnel with a capacity of 500 cmis placed 300 cmsodium citrate, is added to the solution of a few drops of phenolphthalein and pour the ammonia to obtain a crimson coloration. Then extracted in portions with a solution of dithizone with a mass fraction of 0.01%. The extraction is repeated to produce the same green color of the extract. The last batch tested for heavy metal content. This excess dithizone removed by shaking the extract with a solution of dilute ammonia. The layer of carbon tetrachloride should be colorless. To retrieve ditizona passed into a solution of citrate of sodium, the latter is shaken out with several portions of carbon tetrachloride to obtain a colorless lower layer.

Ammonium citrate, dipotassium for ND, 0.5 mol/DMsolution, clean as well as sodium citrate.

Sodium sulfide (sodium sulfide) according to GOST 2053−77, solutions with a mass fraction of 1% and with a mass fraction of 0.05%. Last prepared before use by diluting the solution with a mass fraction of 1%.

Sodium N, N-diethyldithiocarbamate according to GOST 8864−71, a freshly prepared solution with a mass fraction of 0.2%.

Camouflage solutions:

Solution 1; prepared as follows: to 100 cmof 0.5 mol/DMsolution of citrate of ammonium added 32 cm1 mol/DMammonia solution and diluted with water to 450 cm.

Solution 2; prepared as follows: one volume of solution of sodium diethyldithiocarbamate is mixed with nine volumes of solution 1.

Carbon tetrachloride according to GOST 20288−74. If necessary, purify as follows: to 1 DMof carbon tetrachloride is added 0.5 g of solid ditizona and incubated for 1 h in a water bath at 35 °C. Then carry out the Stripping in a glass distillation apparatus.

Ditson (diphenylthiourea) ND the solutions with a mass fraction of 0.01 and 0.002% carbon tetrachloride; prepared as follows: 0.05 g of dithizone dissolved in 50 cmof carbon tetrachloride, was transferred to a separatory funnel with a capacity of 500 cm, pour 200cmof water, 2−3 cmof ammonia and vigorously shaken for 1 min Decison goes into the aqueous layer, colouring it orange. After separation of the layers separate and discard the carbon tetrachloride layer. To the ammonia solution in a separating funnel pour 100 cmof carbon tetrachloride, acidifying with hydrochloric acid until the color changes of the water layer and shaken until the discoloration of the latter.

Solution dithizone in carbon tetrachloride, painted green, is separated from the water layer, washed twice with water and filtered through a dry paper filter into a dry flask of dark glass, then pour 400 cmof carbon tetrachloride and stirred.

The solution was stored in a refrigerator.

Before analysis to check the suitability of the solution dithizone, it is shaken with a solution of dilute ammonia. The layer of carbon tetrachloride should not be painted. Otherwise, a second cleaning solution dithizone.

Dithizone solution with a mass fraction of 0.002% prepared before use by diluting a solution of dithizone with a mass fraction of 0.01% to 5 times with carbon tetrachloride.

By ND phenolphthalein, alcohol solution with a mass fraction of 1%.

Rectified ethyl alcohol GOST 18300−87.

Zinc GOST 3640−94.

Solutions of the zinc standard.

Solution A, prepared as follows: 0.2 g of zinc is dissolved in 15 cm4 mol/DMhydrochloric acid solution. The solution was transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof solution A contains 0.2 mg of zinc (Zn).

Solution B is prepared before use as follows: pipette select 5 cmof solution A in a volumetric flask with a capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.001 mg of zinc (Zn).

(Changed red

action, Rev. N 3).

3.3. Analysis

3.3.1. Electrochemically dissolve approximately 1 g of aluminum in 30 cm4 mol/DMhydrochloric acid solution. The dissolution is carried out according to GOST 12697.7−77. The resulting solution was evaporated prior to the deposition of salts and dissolved salts in the water while heating to obtain a transparent solution. After cooling, transfer the solution into a volumetric flask with a capacity of 100 cm.

3.3.2. The first extraction (extraction amount dithizonate metals).

Take 10−50 cmof the test solution, depending on the assumed mass fraction of zinc in a separating funnel with a capacity of 250 cm, dilute with water to 50 cm.

Then added a solution of sodium citrate at the rate of 10 cmsolution of 0.5 g of aluminium, 2−3 drops of solution of phenolphthalein and ammonia solution dropwise to obtain a crimson coloration. Pour 10 cmof a solution of dithizone with a mass fraction of 0.01% and the contents of the funnel vigorously shaken for 2 min. After separation of the layers, merge the layer of carbon tetrachloride into another separatory funnel, avoiding contact with the aqueous phase in the hole of the crane. The extraction is repeated several times dithizonate portions of dithizone 5−10 cmup until the last portion does not cease to change color after shaking.

The aqueous phase is washed by shaking with several portions of 5 cmof carbon tetrachloride and added to the main extract. The last portion of carbon tetrachloride should be only slightly colored by ditizona

.

3.3.3. The Stripping (separation from copper).

To the extract in the separating funnel add 20 cmof 0.02 mol/DMhydrochloric acid solution and vigorously shaken for 1 min.

Then poured a layer of carbon tetrachloride into another separatory funnel. The aqueous layer should not fall into the hole of the crane. Repeat shaking the organic phase with 20 cmof 0.02 mol/DMhydrochloric acid solution. The layer of carbon tetrachloride is discarded.

Combine hydrochloric acid solution and washed by shaking with 10 cmof carbon tetrachloride. The carbon tetrachloride layer is separated and discarded.

3.3.4. The second extraction (extraction of zinc to colorimetrically).

To the hydrochloric acid solution in a separating funnel add 40 cm of asolution of 2, 10 cmdithizone solution with a mass fraction of 0.002% and shaken for 1 min. After separation of layers, the layer of carbon tetrachloride is transferred to a quartz cylinder with a glass stopper with a capacity of 25 cm.

The extraction is repeated again 10 cmsolution of dithizone. Dissolved in the aqueous phase of dithizon is extracted by shaking with 5 cmof carbon tetrachloride and added to the first two extracts in the cylinder. Solution dithizone and carbon tetrachloride is added from the burette.

To remove excess dithizone diisononyl extract is shaken with a solution of sodium sulfide. To do this, 2−3 separating funnel is poured 10 cmof dilute sodium sulphide solution and one of them transferred the contents of the cylinder, which is shaken one or two times. The layer of carbon tetrachloride is transferred into the next funnel. This operation is carried out until until the aqueous layer will remain colorless. Then washed with a solution of zinc dithizonate by shaking with water and transferred to a cylinder with a glass stopper. Solution dithizonate zinc should be protected from light. No later than 15 min measure the optical density of the solution on the photoelectrocolorimeter or spectrophotometer, given that a maximum of light absorption of solutions corresponds to a wavelength of 538 nm. Solution comparison is carbon tetrachloride.

To remove residual moisture during the filling of the cuvette the solutions were passed through a dry ash-free filter.

At the same time spend control experience. This quartz glass is poured such a quantity of hydrochloric acid required to dissolve the sample, and remove the acid by evaporation to a volume of 0.5 cm, adding 25 cmof water and analyze as described in section 3.3.

The mass of zinc is determined according to the calibration schedule, taking into account the amendment of the control and experience

.

3.4. Construction of calibration curve

In a separating funnel with a capacity of 250 cmpoured in 40 cmof 0.02 mol/DMhydrochloric acid solution and microburette 0; 0,5; 1; 1,5; 2; 2,5; 3 cmstandard solution B, which corresponds to 0; 0,0005; 0,001; 0,0015; 0,0020; 0,0025; 0,0030 mg of zinc.

Add 40 cm of asolution of 2, 10 cmdithizone solution with a mass fraction of 0.002% and then carry out the analysis as described in section 3.3.4.

Solution comparison is the solution, in which zinc was not added.

According to the obtained values of optical density of solutions and the known mass of zinc build a calibration curve.

3.3.1−3.4. (Changed edition, Rev. N 3).

3.5. Processing of the results

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

,

where is the mass of zinc that was found in the calibration graphics mg;

 — the total volume of solution, cm;

 — volume aliquote part of the solution, cm;

the weight of aluminium,

3.5.2. Permissible discrepancies in the results of parallel measurements (at a mass fraction of zinc from 0,0002 to 0,003%) should not exceed 30% precision and 45% reproducibility.

(Changed edition, Rev. N 3).

4. POLAROGRAPHIC METHOD for the DETERMINATION of ZINC (at a mass fraction of zinc from 0.001 to 0.1%)

4.1. The essence of the method

The method is based on polarography of zinc from the properly prepared solution in the voltage interval from minus 0.8 to minus 1.2 V.

4.2. Apparatus, reagents and solutions

Polarograph AC type PU-1 or similar type. Laboratory scales according to GOST 24104−2001 of the 2nd accuracy class with the weighing error of 0.0002 g.

The gaseous nitrogen according to GOST 9293−74.

Aluminum brand A995 according to GOST 11069−2001.

Solution of aluminum 28 g/DM; prepared as follows: 14,00 g of aluminum is placed in a beaker with a capacity of 600 cm, is dissolved in 300 cmof hydrochloric acid diluted 1:1 and added to accelerate the dissolution one or two drops of metallic mercury or chloride of Nickel. The solution was transferred to volumetric flask with a capacity of 500 cm, is diluted to the mark with water and mix.

Bromine according to GOST 4109−79.

Hydroxylamine hydrochloric acid according to GOST 5456−79, a freshly prepared solution with a mass fraction of 10%.

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

Mercury.

Zinc GOST 3640−94.

Solutions of the zinc standard. Solution A, prepared as follows: dissolve 0,1400 g of zinc and 10 cmof hydrochloric acid diluted 1:1, transferred into a measuring flask with volume capacity of 1000 cm, is diluted to the mark with water and mix.

1 cmof solution A contains 0.14 mg of zinc (Zn).

Solution B is prepared before use as follows: a pipette, take 25 cmof solution A in a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

1 cmof solution B contains 0,014 mg of zinc (Zn).

All utensils should be made of borosilicate or of the corresponding quality of glass that does not contain zinc. Allowed to use plastic utensils. You should not use rubber stoppers. Water twice distilled. Nickel chloride according to GOST 4038−79, a solution with a mass fraction of 0.2%.

(Changed edition, Rev. N 1,

3).

4.3. Analysis

4.3.1. A portion of the aluminum 0.7 g were placed in a glass with a capacity of 100−150 cmand dissolved in 20 cmof hydrochloric acid diluted 1:1. Beaker cover watch glass, and heated to dissolve sample. Once dissolved, wash the glass and the side of the Cup with water, add 2−3 drops of bromine and evaporated the solution until a wet residue of salts. The residue is dissolved in a small amount of water and the solution again evaporated to obtain a wet residue of salts. The residue is dissolved in 10−15 cmof hot water, add 2 cmof hydrochloric acid hydroxylamine solution, boil for 1−2 min. then solution was cooled, transferred to a volumetric flask with a capacity of 25 cm, is diluted to the mark with water and mix.

Part of the solution is taken into the cell and Donna mercury, pass nitrogen for 5 min and polarographic zinc in the voltage interval from minus 0.8 to minus 1.2 V when the relevant sensitivity of the instrument. Copper and lead were determined simultaneously from the same solution, polarography copper in the voltage interval from minus 0.05 to minus 0.4 In and lead — from minus 0.35 to minus 0,8 Century

At the same time spend control experience.

The mass of zinc is determined according to the calibration schedule, taking into account the amendment in the reference experiment.

(Changed edition, Rev. N 3).

4.3.2. Construction of calibration curve (with a mass fraction of zinc from 0.001 to 0.01%)

In glasses with a capacity of 150 cmis placed 25 cmof a solution of aluminium in 28 g/DMand of microburette add 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cmof solution B, which correspond to 0; 0,007; 0,014; 0,028; 0,042 and 0.07 mg of zinc. In each glass add 2−3 drops of bromine and evaporated to obtain a wet residue of salts. Then the side of the Cup washed with water and again evaporated to moist residue of salts. The remainder of the salt is dissolved by heating in 10−15 cmof water, pour 2 cmof a solution of hydroxylamine hydrochloric acid and boil for 1−2 minutes Further analysis performed as described in section 4.3.1.

According to the data obtained polarographically solutions, and the known mass of zinc build a calibration curve.

When you replace the capillaries, you need to build a new schedule.

(Changed edition, Rev. N 1, 3).

4.3.3. Construction of calibration curve (with a mass fraction of zinc from 0.01 to 0.1%)

In glasses with a capacity of 150 cmis placed 25 cmof a solution of aluminium in 28 g/DMand of microburette add 0; 0,5; 1,0; 2,0; 3,0 and 5,0 cmof solution A, which correspond to 0,07; 0,14; 0,28; 0,42 and 0.70 mg of zinc. Then build a calibration curve, as specified in clause 4.3.2.

4.4. Processing of the results

4.4.1. Mass fraction of zinc in percent () is calculated by the formula

,

where is the mass of copper was found in the calibration graphics mg;

the weight of aluminium,

4.4.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in table.2.

Table 2

(Changed edition, Rev. N 1, 3).

5. ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF ZINC CONTENT

5.1. The essence of the method

The method is based on dissolving the sample in hydrochloric acid and the resulting solution sprayed in the flame acetylene-air. Using a lamp with a hollow cathode for zinc, measured by absorption at a wavelength of 213,8 nm.

(Changed edition, Rev. N 1).

5.2. Apparatus, reagents and solutions

All utensils should be made of borosilicate or of the corresponding quality of glass that does not contain zinc. Allowed to use plastic utensils. You should not use rubber stoppers.

Spectrophotometer atomic absorption model of Perkin-Elmer, «Saturn» or similar type.

Laboratory scales according to GOST 24104−88 of the 2nd accuracy class with the weighing error of 0.0002 g.

Lamp with hollow cathode for zinc.

Water twice distilled.

Hydrochloric acid by the GOST 3118−77, a solution of 1:1.

Sulfuric acid GOST 4204−77, a solution of 1:1.

Hydrofluoric acid according to GOST 10484−78.

Nitric acid GOST 4461−77 diluted 1:1.

Hydrogen peroxide according to GOST 10929−76 solution with a mass fraction of 3%.

Acetone according to GOST 2603−79.

Mercury metal according to GOST 4658−73.

Nickel chloride according to GOST 4038−79, a solution with a mass fraction of 0.2%.

Zinc GOST 3640−94.

Aluminum brand А999 according to GOST 11069−2001, zinc.

Immediately before use, the chips are cleaned in a small amount of nitric acid.

The treated chips are washed with water and dried with acetone.

A solution of aluminium 40 g/DM: 40.0 g of aluminium is placed in a beaker with a capacity of 1000 cm, in small portions was added 500 cmof a solution of hydrochloric acid 1:1 and 250 cm.of concentrated hydrochloric acid. Add a single drop of mercury or 1 cmof a solution of Nickel chloride to accelerate the dissolution. Add a few drops of hydrogen peroxide, then the solution was boiled for few minutes to remove excess peroxide. After cooling, the solution is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

Standard solutions of zinc

A. a solution of 1.0 g of zinc is dissolved in 25 cmof a solution of hydrochloric acid 1:1 in a beaker with a capacity of 400 cm, diluted with water, transferred into a measuring flask with volume capacity of 1000 cm, is added to the mark with water and mix. 1 cmof solution A contains 1 cmof zinc.

Solution B. 100 cmof solution A is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof a solution contains 0.1 mg of zinc.

Solution V. 100 cmof solution B is transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix.

1 cmof the solution contains 0.01 mg of zinc.

(Redrafted From

M. N 1, 3).

5.3. Analysis

5.3.1. 1 g samples were placed in a glass with a capacity of 400 cm, cover with a watch glass and dissolved in 25 cmadd small portions of hydrochloric acid solution 1:1, if necessary, the solution is heated.

Add 2 cmof hydrogen peroxide, then heated the solution to boiling to remove excess peroxide. When the mass fraction of zinc from 0.001 to 0.05% solution transferred to a volumetric flask with a capacity of 100 cm, after cooling, is poured to the mark with water and mix.

When the mass fraction of zinc from 0.05 to 0.2% solution transferred to a volumetric flask with a capacity of 500 cm, after cooling, is poured to the mark with water and mix. Simultaneously with the analysis and under the same conditions prepare a solution of the reference experiment, using the same reagents and in the same quantities, but instead of sample add 1 g of aluminium, zinc.

Install the lamp with hollow cathode for zinc. Turn on the device and leave until its full stabilization. Set the device at a wavelength of 213,8 nm and is selected in accordance with the design of the instrument sensitivity and the size of the gap. Pressure of gases air-acetylene are used to set the device design. The zero of the instrument set on the water.

The flame alternately spraying solutions to build the calibration curve, the sample solution, the solution in the reference experiment and measure the absorbance.

From the obtained values of absorbance of solutions to construct the calibration curve subtract the value of absorbing solution not containing zinc, and according to the obtained values of absorption and the known mass of zinc build a calibration curve.

(Changed edition, Rev. N 1, 3).

5.3.2. When the mass fraction of zinc from 0.001 to 0.05% in 11 volumetric flasks with a capacity of 100 cmis placed 25 cmof a solution of aluminium, then from a burette add alternately 1,0; 2,0; 4,0; 6,0; 8,0; 10,0 cmsolution and 2,0; 3,0; 4,0; 5,0 cmof solution B, which corresponds to 0,01; 0,02; 0,04; 0,06; 0,08; 0,10; 0,20; 0,30; 0,40; 0,50 mg of zinc. In the eleventh flask, a solution of zinc is not added. The solutions were topped up to the mark with water and mix.

5.3.3. When the mass fraction of zinc from 0.05 to 0.2% in blend* volumetric flasks with a capacity of 100 cmis placed 5 cmof a solution of aluminium, then from a burette add alternately 5,0; 8,0; 10,0; 12,0; 15,0; 20,0 cmof solution B, which corresponds to 0,5; 0,8; 1,0; 1,2; 1,5; 2,0 mg of zinc. In the seventh flask solution B is added. The solutions were topped up to the mark with water and mix.
________________
* The text matches the original. — Note the manufacturer’s database.

5.4. Processing of the results

5.4.1. Mass fraction of zinc in percent () is calculated by the formula

,

where is the mass of zinc in the sample solution found by the calibration schedule, mg;

the volume of the solution to plot, cm;

 — the volume of the sample solution, cm;

 — the weight of the portion of the sample,

5.3.2−5.4.1. (Changed edition, Rev. N 1).

5.4.2. Permissible discrepancies in the results of parallel definitions should not exceed the values given in table.3.

Table 3

(Changed edition, Rev. N 1, 3).