GOST 16273.1-85

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  ГОСТ 16273.1-85

GOST 16273.1−85 Selenium technical. Method of spectral analysis

GOST 16273.1−85

Group B59

STATE STANDARD OF THE USSR

SELENIUM TECHNICAL

Method of spectral analysis

Technical selenium. Method of spectral analysis

AXTU 1709

Valid from 01.07.86
to 01.07.91*
_______________________________
* Expiration removed
by the resolution of Gosstandart of Russia from 04.06.91 N 782
(IUS N 9, 1991). — Note the CODE.

DEVELOPED by the Ministry of nonferrous metallurgy of the USSR

PERFORMERS

B. M. Rogov, E. N. Gazalov, Yu.N.Semavin, O. D. Ryabkova, E. B. Makovsky

INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

Member Of The Board Of A. P. Snurnikov

APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from January 30, 1985 N 208

REPLACE GOST 16273.1−71


This standard specifies the emission spectral method for the determination of copper, iron, lead, mercury, magnesium, tellurium, arsenic, antimony, aluminum technical Selene with a mass fraction of selenium from 97.5% and above range mass fraction, %:

Measurement of mass fractions of impurities in selenium based on the evaporation of the sample and the excitation spectrum with the application of arc AC.

1. GENERAL REQUIREMENTS

General requirements for method of analysis according to GOST 16273.0−85.

2. APPARATUS, MATERIALS, REAGENTS, SOLUTIONS

The spectrograph of any type with being (or single lens) illumination system of the slit.

(You can also use the spectral instruments with photoelectric registration of spectrum).

Microphotometer of any type.

The generator of the arc AC of any type.

Laboratory scales with a maximum load of 200 g.

Porcelain mortar according to GOST 9147−80 or agate pestle.

Porcelain Cup according to GOST 9147−80.

Boxy glass according to GOST 25336−82.

Drying oven laboratory.

The infrared lamp according to GOST 13874−76.

Grinding machine graphite electrodes of any type.

The sieve according to GOST 0071 6613−73*.
________________
* Valid GOST 6613−86. — Note the CODE.

Photographic plates spectrographic type I sensitivity 3−5 units, type II, ES or UPS sensitivity from 10 to 20 units, or other contrast materials.

The pure spectral graphite electrodes grades C-3, ОС4−7-4 according to GOST 4425−72, with a diameter of 6 mm, a length of 30−50 mm with a crater diameter 3,8−4 mm, a depth of 4−5 mm and a diameter of 6 mm, a length of 30−50 mm, sharpened to a hemisphere or a cone.

Graphite powder of high purity according to GOST 23463−79 or graphite powder manufactured by crushing pure spectral graphite electrodes.

Allowed the use of other contrast working developer and fixer.

Standard samples for calibration.

Bismuth oxide according to GOST 10216−75.

Cobalt oxide according to GOST 4467−79.

The technical rectified ethyl alcohol according to GOST 18300−72*.
________________
* Valid GOST 18300−87. Here and hereinafter. — Note the CODE.

Sodium salitsilovaya according to GOST 17628−72, 5% solution in alcohol.

Sodium chloride according to GOST 4233−77.

3. PREPARATION FOR ASSAY

3.1. Preparation of standard samples for calibration are given in mandatory Appendix 1.

For the purposes of calibration allowed the use of standard samples of any class certified in the prescribed manner.

3.2. Preparation of the buffer mixture

Mixture 1: in a porcelain mortar is placed a suspension of graphite powder with a mass of 0.87 g and 0.13 g of cobalt oxide; grind until smooth.

Blend 2: blend 1 select a sample of 0.10 g, carry it in a porcelain mortar, add 0.28 g of bismuth oxide, 0.62 g of graphite powder and stirred.

For the preparation of the buffer mixture in a porcelain Cup placed 1 g of sodium chloride and pour the water until the salt completely dissolves. The resulting solution was added to 8.90 g of graphite powder and 0.10 g of a mixture 2; mixed and dried on the tile. The dry mixture is ground and sieved through a sieve with a mesh 0071. The residue on the sieve mesh is ground and sieved again. The resulting mixture contains 10% sodium chloride, 0.25% of bismuth, 0.01% cobalt.

The number of prepared buffer mixture can be increased. The buffer mixture is allowed to cook by introducing appropriate amounts of nitric acid solutions of bismuth and cobalt in the mixture of graphite powder with sodium chloride.

4. ANALYSIS

4.1. Analysis of selenium (mass fraction of main component from a 97.5 to 99.0%)

4.1.1. Samples and standard samples for calibration is mixed with the buffer mixture in the ratio 1:2 (200 mg sample and 400 mg buffer mixture) in a porcelain (or agate) mortar for 30−35 min. and fill the craters of graphite electrodes, previously annealed for 10−15 seconds in the arc of an alternating current power 10−12 A. the Electrodes high purity-7−4 not pre-calcined. From each sample and the standard sample for the calibration take two sample and prepare three electrode.

4.1.2. The spectra photographed using a three-step attenuator and a width of slit of the spectrograph 0.012 mm. the Coverage gap is being single lens or a condenser. Intermediate the aperture set depending on the sensitivity of photographic plates.

Evaporation of the sample and the excitation spectrum is produced in the arc AC And 7−8, the arc gap of 2.5 mm, exposure time — 75 S.

In the right part of the cassette put the record type I size 9x6 cm, in the left, close to it, record the type II ES or UPS size 9x12 cm

In the spectrograms of the first standard sample for the calibration line Selena 241,35 nm should be resolved with a line of iron 241,33 nm (in the most relaxed step).

Photographed on one pair of plates of three each spectrum of the sample and the standard samples. Repeat the shooting on the second pair of plates.

The plate shown at a temperature of (20±1) °C (the time of development indicated on the packaging plate), fixed, washed for 18−20 min. in running water, rinsed with distilled water and dried.

If transmission optics of the spectrograph shortwave part of the ultraviolet region of the spectrum or insufficient sensitivity of the photographic material lines of arsenic and tellurium in the spectra of the standard samples with the lowest content of impurities have a low density of blackening (less than 0.10), then the definition of these elements should be held on a separate photographic plate. For this photograph the spectra of samples and standard samples under the conditions specified above, but in the same place plates off spectra three to five electrodes. This should take into account background, if it is blackening in the spectrum is comparable to the blackening of analytical lines.

4.1.3. Fotometrirovanie spectrograms

Fotometrirovanie of spectrograms is performed on microphotometer when the width of the slot not more than 0.2 mm.

The resulting spectrograms to measure the density of the blackening of analytical lines of the determined elements and line elements, serving internal standard , wavelength of which is given below.

For photometry you should choose those steps of attenuation, in which the density of blackening of the measured lines lie in the region of normal.

Allowed to use as comparison lines of the background near the line of the element, if its density is not less than 0.20.

4.1.4. Processing of the results

Calculate the difference of pochernenija , find the arithmetic mean for the three spectra of each standard sample and the sample. On the found values for standard samples to build a calibration curve in the coordinates where the mass fraction of impurities in the standard samples in percent. According to the schedule, find the mass percent of impurities corresponding to the calculated sample values .

The final result of the analysis taking the arithmetic mean of the results of parallel measurements obtained from two batches of three spectrograms taken with the two pairs of plates.

4.2. Analysis of selenium (mass fraction of main component of more than 99,0%)

4.2.1. Preparation of standard samples for calibration are given in mandatory Appendix 1.

For dilution of samples and standard samples for the calibration using buffer mixture prepared according to claim 3.2.

4.2.2. Samples and standard samples mixed with a buffer mixture in a porcelain (or agate) mortar in the ratio 2:1 (600 mg of sample and 300 mg buffer mixture) for 30−35 min. Prepared samples and standard samples fill the craters of graphite electrodes. From each sample and the standard sample take two sample and prepare three electrode.

4.2.3. Photographing spectra, spectrograms fotometricheskie and processing of results — PP.4.1.2−4.1.4.

5. DETERMINATION OF ANTIMONY

5.1. Analysis of selenium (mass fraction of iron no more than 0.02%)

5.1.1. Preparation of samples are given in mandatory Appendix 1.

5.1.2. For the preparation of the buffer mixture is ground in a porcelain Cup of 0.28 g of bismuth oxide with 0.72 g of graphite powder (the first mixture). Second a porcelain Cup placed 1 g of sodium chloride and add water to dissolve the salt. The resulting solution was added to 8.90 g of graphite powder and 0.10 g of the first mixture, all mixed and dried on the tile. The resulting mixture was triturated until a homogeneous mass is 30−40 min Prepared buffer mixture containing 10% sodium chloride and 0.25% of bismuth.

The buffer mixture can be prepared by introducing the appropriate amount of solution of nitrate of bismuth into a mixture of graphite powder with sodium chloride.

The number of simultaneously prepared buffer mixture depending on the needs can be increased.

5.1.3. Preparation for assay

Of the sample and standard samples for calibration is mixed with the buffer mixture in a weight ratio of 2:1 (600 mg of sample and 300 mg buffer mixture). The mixing is carried out in a mortar for 30−40 minutes, then stuffed with the mixture craters of graphite electrodes, previously annealed for 10−15 seconds in the arc of an alternating current power 10−12 A. From each sample and the standard sample take two sample and prepare three electrode.

5.1.4. Photographing a spectrum

Photographing the spectra produced in the spectrograph with single lens or three-lens Achromat condenser through a three-stage attenuator. The width of the slit of a spectrograph — 0.012 mm, intermediate diaphragm — round. The arc gap of 2.5 mm.

In the cassette placed a plate type II or ES. Records are selected for sensitivity such that the blackening of the background in the spectrum near the line of antimony 259,81 nm was not less than 0.10 (when photographing spectra in the stipulated standard conditions).

Evaporation of the sample and the excitation spectrum is carried out in the arc AC at 7−8 And exposure time — 75 S.

Pictures on one disc three spectrum of each sample and the standard sample. Shooting repeat on the second plate.

Plate shown (the time of development is indicated on the package of records) at (20±1) °C, fixed, washed 18−20 min in running water, rinsed with distilled water and dried.

5.1.5. Fotometrirovanie spectrograms and processing of analysis results

Fotometrirovanie carried out at a slit width of microphotometry not more than 0.2 mm.

Measure the density of pochernenija lines of antimony — 259,81 nm and bismuth — 269,66 nm, choosing to photometry the steps of weakening, in which the density of blackening of the measured lines lie in the region of normal.

Calculate the difference in the density of pochernenija line of antimony and bismuth , find arithmetic mean for the three spectra of each standard sample and the sample. Construction of calibration curve, determination of the mass fraction of antimony and processing of results — p. 4.1.4.

5.1.6. Mass fraction of antimony from 0.002 to 0.05% in the samples in which iron not more than 0.02%, can define also, in the spectra obtained in the determination of the mass fraction of impurities in selenium, as given in sect.3, if the introduction of antimony in standard samples.

5.2. Analysis of selenium (mass fraction of iron than 0.02%)

5.2.1. Preparation of standard samples for calibration are given in mandatory Appendix 1.

5.2.2. Preparation of the buffer mixture

In a porcelain Cup placed 1 g of sodium chloride and add water to dissolve the salt. The resulting solution was added to 0.20 g of bismuth oxide and 8,80 g of graphite powder, all mixed and dried on the tile. The dry powder is thoroughly mixed and mulled. In the prepared buffer mixture and 2% bismuth oxide, 10% sodium chloride.

5.2.3. Sample preparation and standard samples according to claim 5.1.3.

5.2.4. Photographing spectra

The spectra photographed using a three-step attenuator and a width of slit of the spectrograph 0.012 mm. Coverage gaps — being a condenser. Being permitted to replace condenser single lens and a first condenser of achromatic objectives (75 mm) normativnym condenser with the same focal length.

Intermediate diaphragm — round.

The arc gap of 2.5 mm.

In the left part of the cassette (in the direction of the short-wave part of the spectrum) put the plate type II or ES, sensitized with a solution of salicylic sodium in ethyl alcohol (reference Annex 2). The plate is selected so that blackening of the background near the line of antimony 231,15 nm was not less than 0.20.

Evaporation of the sample and the excitation spectrum is produced in the arc AC And 7−8, the exposure time of 75 s.

Shooting repeat on the second plate.

5.2.5. Fotometrirovanie spectrograms and processing of results

Measure the density of blackening of the line of antimony 231,15 nm line of bismuth 240,09 nm, choosing electrophoretic those steps in which blackening of the measured lines lie in the region of normal.

Calculate the difference of pochernenija line of antimony and bismuth . Find the arithmetic mean for the three spectra of each test sample and standard sample.

Construction of calibration curve, determination of the mass fraction of antimony and processing of results — p. 4.1.4.

ANNEX 1 (mandatory). PREPARATION OF STANDARD SAMPLES FOR CALIBRATION

ANNEX 1
Mandatory

1. Standard samples for calibration, prepared for each company according to the above method should be certified in the prescribed manner.

2. Allowed the preparation of standard samples for calibration of the oxides of metals and solutions of salts.

3. Preparation of standard samples for calibration of the oxides of the metals in the analysis of selenium with a mass fraction of the main component from a 97.5% to 99%.

3.1. Reagents

Selenium of high purity according to GOST 6738−71.

Tellurium of high purity according to GOST 18428−81.

Copper (I) oxide under GOST 16539−79.

Lead (II) oxide according to GOST 9199−77.

Iron oxide according to GOST 4173−77.

Mercury oxide yellow according to GOST 5230−74.

Arsenic anhydride.

Aluminium oxide active according to GOST 8136−76*.
________________
* Standards 8136−85. Here and hereinafter. — Note the CODE.

Magnesium oxide according to GOST 4526−75.

The technical rectified ethyl alcohol according to GOST 18300−72.

3.2. Sample preparation

The sample is pre-crushed and sifted through a sieve 0071К weight: 0,138 g — copper-oxide, 0.118 g of lead oxide, 1,587 g — iron oxide, 0,398 g of oxide of mercury, to 0.488 g — arsenious anhydride, 0,703 g — aluminum oxide, 0.182 g of magnesium oxide, 1,850 g of tellurium is placed in a mortar and mixed. For more homogeneous use of ethyl alcohol at the rate of 1−1,5 cmper 1 g of the mixture. Fray to drying of the mixture.

Allowed the use of mechanical mixers type of SMB.

From the resulting mixture, take the sample weight of 1.0 g and triturated in a mortar with 2.35 g of selenium-framework.

Received head sample with a mass fraction of iron 6%, 0.6% lead, copper, magnesium, 10% of tellurium, 2% of aluminium, arsenic, mercury.

Working samples for calibration prepare a serial dilution of a standard sample head first 10 times, then each subsequent 2−2. 5 times the selenium-framework.

Composition of standard samples for calibration are given in table.1.

Table 1

Depending on the composition of the analyzed samples allowed to change the mass fraction or exclusion of certain impurities with the appropriate conversion structure.

4. Preparation of standard samples from solutions of metal

4.1. Reagents and solutions

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

Nitric acid GOST 4461−77 and diluted 1:1.

Tartaric acid according to GOST 5817−77.

Copper GOST 859−78*.
______________
* On the territory of the Russian Federation GOST 859−2001. — Note the CODE.

Lead according to GOST 3778−77*.
______________
* On the territory of the Russian Federation GOST 3778−98. — Note the CODE.

Iron restored.

Mercury GOST 4658−73.

Tellurium GOST 18428−81.

Aluminium GOST 11068−74.

Magnesium GOST 804−72*.
________________
* On the territory of the Russian Federation GOST 804−93 — note the CODE.

Selenium GOST 6738−71.

Copper oxide under GOST 16539−79.

Lead oxide according to GOST 9199−77.

Iron oxide according to GOST 4173−77.

Mercury oxide yellow according to GOST 5230−74.

Aluminium oxide active according to GOST 8136−76.

Magnesium oxide according to GOST 4526−75.

Antimony trioxide.

Arsenic anhydride.

Copper nitrate.

Lead (II) nitrate according to GOST 4236−77.

Iron (III) nitrate 9-water according to GOST 4111−74.

Mercury nitrate 1-water according to GOST 4520−78.

Aluminium nitrate 9-water according to GOST 3757−75.

Magnesium nitrate according to GOST 11088−75.

Copper (II) carbonate basic GOST 8927−79.

Lead carbonate according to GOST 10275−74.

Magnesium carbonate basic water according to GOST 6419−78.

Solutions:

nitrate of copper, 2 mg of copper in 1 cm,

nitrate of lead 2 mg lead 1 cm,

nitrate of iron is 20 mg of iron per 1 cm,

nitrate of mercury, 2 mg of mercury in 1 cm,

nitrate of tellurium is 10 mg of tellurium in 1 cm,

nitrate of aluminium is 10 mg of aluminum per 1 cm,

nitrate of magnesium — 2 mg per 1 cm.

These solutions were prepared by dissolving calculated quantities of metals, their oxides, nitrate or carbonate salts in nitric acid, is evaporated to wet salts. Wet residues will be dissolved in water, the solutions were transferred to volumetric flasks, adjusted to the mark with water and mix.

The solution of arsenic: dissolve 0,264 g of water-soluble modifications of arsenious anhydride in water, transfer the solution into a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution contains 2 mg of arsenic in 1

m.

4.2. In a volumetric flask with a capacity of 100 cmis placed 15 cmnitric acid solutions of iron, magnesium, copper, lead, 10 cmof a solution of aluminum, made up to the mark with water and mix.

A mixture of 1: a suspension of graphite powder with a mass of 6.40 g is placed in a porcelain Cup, poured 20 cmof the prepared solution and dried. The resulting powder was added successively with 10 cmof nitric acid solutions of mercury, tellurium and 10 cmof a solution of arsenic, drying the mixture after the introduction of each solution to remove odors of oxides of nitrogen (after the introduction of the solution of mercury dried at a temperature not higher than 50 °C).

Blend 2: blend 1 is mixed with the selenium-based in a weight ratio of 2:1. The resulting mixture is a standard sample 1−1 (see table.1).

A series of samples for calibration is prepared by dilution of the mixture 1 and each of the other calibration samples graphite powder in 2−2,5 times. Each of the prepared calibration samples are mixed with the selenium-based in a weight ratio of 2:1. The content of impurities in the obtained samples counting after mixing with selenium-based. Standard samples for calculation contain a number of impurities are given in table.1.

5. Preparation of standard samples for calibration of the oxides of the metals in the analysis of selenium with a mass fraction of main component > 99%

5.1. Substrate preparation of standard samples for calibration

As the basis of standard samples used selenium of high purity. Check the contents of the designated impurities in the base: the crushed selenium sifted through a sieve with a mesh 0071К and stuffed three of a graphite electrode having a crater with a diameter of 3.8−4 mm, 4−5 mm depth, pre-annealed with protivoelektrodom in the arc AC at 18 And within 20 sec.

Spectra Selena photograph on the spectrograph with single lens or three-lens Achromat, the lighting system at slit width 0.012 mm the plate type II or ES. Evaporation of the sample and the excitation spectrum is carried out in the arc AC 18 A. exposure Time 30 s. After development and fixation of plates to check the presence in the resulting spectrograms of the analytical lines of the determined elements.

If these lines are detected, after preparation of standard samples must determine the mass fraction of impurities in the base by the method of additions (mandatory Annex 3).

The characteristic curve is permitted to build by the spectra of standard samples, taken through a three-stage attenuator (reference Appendix 4).

5.2. The reagent according to claim 3.1.

5.3. Preparation of standard samples

The sample is pre-crushed and sifted through a sieve 0071 weight: 0,715 g — iron oxide, 0.125 g of copper oxide, 0,540 g of lead oxide, 0,540 g of the oxide of mercury, 0,657 g — arsenious anhydride, 0,833 g — magnesium oxide, 0,188 g — aluminum oxide, 2.00 g of tellurium, 4,40 g — Selena-basics are placed in a porcelain mortar and mixed. For more homogeneous use of ethyl alcohol at the rate of 1.0 to 1.5 cmper 1 g of the mixture, and then ground before drying.

From the prepared mixture sample mass of 0.5 g and triturated in a mortar with 4.5 g of selenium-framework. Received the head sample contains 0.1% of aluminum, copper, 0.5% iron, lead, mercury, arsenic, magnesium, and 2% tellurium.

Working samples for calibration prepare a serial dilution of a standard sample head first 10 times, then each subsequent 2−2. 5 times the selenium-framework.

Composition of standard samples for calibration are given in table.2.

Table 2

Depending on the composition of the analyzed samples allowed to change the mass fraction or exclusion of certain impurities with the appropriate conversion structure.

6. Preparation of standard samples of solutions of metals

6.1. Reagents and solutions

Reagents and solutions — according to claim 4.1.

The solution of nitrate of iron: 2 mg of iron per 1 cm.

6.2. Sample preparation

In a volumetric flask with a capacity of 100 cmis placed 5 cm innitric acid solutions of copper and aluminium, 25 cmnitrate solutions of magnesium, iron and lead is brought to the mark with water and mix.

A mixture of 1: a suspension of graphite powder with a mass of 6.60 g is placed in a porcelain Cup, add 10 cmof the prepared solution and dried. The resulting powder was added sequentially 2.5 cmsolutions of arsenic and mercury, 2.0 cmnitric acid solution of tellurium, drying the mixture after the introduction of each solution (after the introduction of mercury dried at a temperature not above 50 °C).

Blend 2: blend 1 is mixed with the selenium-based in a weight ratio of 2:1. The resulting mixture is a standard sample 1−2.

A series of samples for calibration is prepared by dilution of the mixture 1 and each of the other calibration samples graphite powder in 2−2,5 times. Each of the prepared calibration samples are mixed with the selenium-based in a weight ratio of 2:1. The content of impurities in the obtained samples counting after mixing with selenium-based. Standard samples for calculation contain a number of impurities are given in table.2.

7. Preparation of standard samples for calibration in the determination of the mass fraction of antimony

7.1. Reagents

Selenium GOST 6738−71.

Of antimony trioxide.

7.2. Sample preparation

The sample is pre-crushed and sifted through a sieve 0071 Selena-basis weight of 4.40 grams of antimony trioxide with a mass of 0.60 g was stirred in a porcelain mortar. The mixture contains 10% antimony. Serial dilution of this mixture selenium-based (not more than 10 times in one session) to prepare standard samples for calibration, containing 0,1; 0,05; 0,02; 0,01; 0,005 and 0,002% antimony.

ANNEX 2 (informative). SENSITIZATION OF THE PLATES

ANNEX 2
Reference

Optical sensitizing dry plates is the method of «bathing».

Plates subjected to sensitization by the method of «bathing», pre-washed in distilled water for 5 min. It is necessary for more uniform penetration of sensitization.

Next, the plate is immersed for 30 s in 5% solution of sodium salicylanilide in 96% strength ethanol and, after wiping the uncovered emulsion side of the plate and dried. This record is not yet sensitized and may persist in this form for quite a long time. For sensitization, it is sufficient to immerse it in water or in 30% alcohol. Film sensitizer formed on the plate, when this is dissolved, and the solution of it, diffusing inside the layer of the plate, causes sensitization.

The duration of the sensitising solution on the photosensitive layer is in the range of 2−5 minutes (increase time raises a veil on the plate).

The solution temperature should not exceed 20 °C, it is necessary for this energetic swaying of the tub.

After sensitization is used in rinse (about 5 min) in a water-alcohol mixture (2:1) and then in pure alcohol to accelerate drying. The speed of drying sensitized plates 15−20 minutes, convenient to use not heated to more than 30−35 °With the air.

APPENDIX 3 (obligatory). DETERMINATION OF IMPURITIES IN THE BASIS OF STANDARD SAMPLES FOR CALIBRATION BY METHOD OF ADDITIONS

APPENDIX 3
Mandatory

1. The basis of standard samples and samples 6−2, 5−2, 4−2, 3−2 mixed with the buffer mixture according to claim 4.2.2 of this standard and fill in the craters of graphite electrodes, prebaked for 10 s at 18 And the arc AC. The crater diameter of the electrode is 3.8−4 mm, depth 4−5 mm.

Spectra photographed with the spectrograph being system of the slit illumination via the three-step attenuator and a width of slit of 0.012 mm to a record type II or ES. Evaporation of the sample and the excitation spectrum in the arc AC 18 A. exposure Time 30 s. one of the plates photographed three of the spectrum of each calibration sample and the basics. On this same plate photographed the first spectrum of the calibration sample through a nine-reliever.

2. Instead of building a characteristic curve of photographic plates for spectrum photographed through a nine-reliever, allowed to build the curve by the spectra of calibration samples captured using a three-step attenuator (reference Appendix 4).

3. Survey spectra repeat for the second plate.

Manifestation and fixation is carried out as specified in clause 4.1.2 of this standard.

According to the obtained spectrograms determine the mass fraction of impurities in the base by the method of additions.

Build a graph of the intensity of the analytical lines of the value of impurity content in the standard sample. Extrapolating the calibration curve to its intersection with the abscissa axis determines the impurity content in the standard samples.

The results of the analysis obtained as the average of results on two plates, add to the content of impurities in the calibration samples.

ANNEX 4 (reference). THE CONSTRUCTION OF THE CHARACTERISTIC CURVE OF PHOTOGRAPHIC PLATES IN THE SPECTRA OF CALIBRATION SAMPLES TAKEN THROUGH A THREE-STAGE ATTENUATOR

ANNEX 4
Reference

The photometer measures the blackening of the lines of the designated element in the spectra of the calibration samples in all three steps of the attenuator. Denote these conditional steps like 100, 50 and 10%. Calculate the difference of the blackening of the lines 100 and 50% steps . For those spectra in which two steps of attenuation are in the region of normal pochernenija, this difference is constant, equal to

,

where is the contrast ratio of the photographic plates;

 — the difference between the transmittance of the attenuator steps (passport).

The y-axis is applied to the graph paper, plotting the y-axis blackening in the scale of 1 mm = 0.01 units, starting from 0.

Calculate the average of five or six difference values of pucherani between 100 and 50% steps for the region of normal pucherani .

Point 1 are arbitrarily chosen abscissa and ordinate equal to the blackening of the beginning of the straight portion of the characteristic curve (approx 0,50 record type ES). From point 1 to the right count the number of millimeters equal to the difference between transmittance of 100% and 50%-tion steps of the attenuator (attenuator data sheet) multiplied by 100 and put a point 2.

From the 2 point lay up the number of millimeters equal to the average value of the difference of pochernenija multiplied by 100 and put a point 3.

The resulting point 3 connect a straight line from point 1 and continue straight up to 1,80. This video corresponds to the region of normal pucherani characteristic curve.

In cases where the blackening of the lines in the 100% step is too large, instead of the difference between 100 and 50% steps building is carried out by difference between 50 and 10% steps.

To build the field of neoteric use spectra in which the first of the steps is in the normal range, the second — in neoteric.

Find of the spectrum at the straight portion of the characteristic curve point, the ordinate of which is equal to the blackening line at 100% (or 50%) step. From this point to the left count the number of millimeters equal to the difference between the transmittance of the attenuator steps, multiplied by 100, and the abscissa to find the point with ordinate equal to the blackening of the same line in a more relaxed step.

So come with all measured pochernenija. Connect the resulting points with a smooth curve since the beginning of the straight section.

On the x-axis is applied to the values in the scale of 1 mm =0.01 units, starting from an arbitrarily chosen origin.