Some standard content:
Chemical Industry Standard of the People's Republic of China
HG2351-92
Cadmium Red Pigment
Published on July 14, 1992
Ministry of Chemical Industry of the People's Republic of China
Published on May 1, 1993
Cadmium Red Pigment
This standard adopts the international standard ISO4620-1986 "Specifications and Test Methods for Cadmium Pigments" with reference to it. 1 Subject Content and Scope of Application
HG235192
This standard specifies the technical requirements, test methods, inspection rules, packaging, marking, transportation and purchase and storage of cadmium red pigments suitable for general purposes.
This standard applies to cadmium red pigments made from soluble cadmium salts, sodium sulfide and selenium powder as raw materials. This product is mainly used in pond porcelain, glass, paint, plastics and rubber.
2 Reference standards
GB1711
Comparison of thermal stability of pigments in baking paints Determination of pH value of aqueous pigment suspensions
GB1717
GB1864
Comparison of pigment colors
GB5211.15
GB5211.18
GB5211.19
GB6682
GB9760
GB7686
GB9285
GB9 287
Determination of the water-soluble matter of pigments by cold extraction
Determination of the volatile matter of pigments at 105°C
Determination of the oil absorption of pigments
Determination of the sieve residue of pigments by water-based manual operation Determination of the relative tinting strength and diluted colour of colouring pigments by visual comparison Specification for water for the laboratory
Paints and varnishes Preparation of acid extracts of liquid or powdered paints General method for the determination of arsenic in chemical products Sampling of raw materials for paints and varnishes
Comparison of the degree of dispersibility of pigments Oscillation method
Determination of the "soluble" metal content of paints and varnishes Part 1: Determination of lead content - Flame atomic absorption spectrometry and dithiol spectrophotometry
Paints and varnishes - Determination of "soluble" metal content Part 2: Determination of antimony content - Flame atomic absorption spectrometry and rhodamine B spectrophotometry
Paints and varnishes - Determination of "soluble" metal content Part 3: Determination of barium content - Flame atomic emission spectrometry
Paints and varnishes - Determination of "soluble" metal content Part 4: Determination of cadmium content - Flame atomic absorption spectrometry and polarography
Paints and varnishes - Determination of "soluble" metal content Part Part VI: Determination of total chromium content in the liquid part of paint GB9758.6
Determination of "soluble" metal content in paints and varnishes Part VII: Determination of mercury content in the pigment part of paints and the liquid part of water-dilutable paints Flameless atomic absorption spectrometry Approved by the Ministry of Chemical Industry of the People's Republic of China on July 14, 1992 and implemented on May 1, 1993
Product classification
According to the use, cadmium red pigments are divided into the following three types: HG2351-92
Type I: Concentrated variety. In order to adjust its relative tinting strength, the amount of body pigment contained in this type of pigment shall not exceed 30% (m/m). Type I: Light variety. In order to facilitate processing, the amount of body pigment contained in this type of pigment shall not exceed 70% (m/m). Type I: Pure variety. This pigment is basically pure and does not contain any body pigment. Technical requirements
Cadmium red pigment is an inorganic color pigment, mainly composed of mixed crystals of cadmium sulfide and cadmium selenide, in which part of the cadmium can be replaced by zinc, but it shall not contain organic substances, other colored inorganic pigments and luminescent agents. The technical indicators of cadmium red pigment shall meet the requirements of Table 1. Table 1
Total amount (cadmium (Cd) ± zinc (Zn) + selenium (Se) ± sulfur (S) J, % soluble in 0.07mol/L hydrochloric acid, % antimony (Sb)
arsenic (As)
cadmium (ca)
chromium (Cr)
lead (Pb)
selenium (Se)
volatile matter at 105℃, %
water soluble matter (cold extraction method), %
pH of water suspension
sieve residue (45μm), %
color (compared with standard sample)
relative tinting strength (compared with standard sample), %
ease of dispersion μm/30min
oil absorption + g/100g
heat Stability (compared with standard sample)
Superior productFirst-class productQualified productSuperior product
First-class productQualified productSuperior product
The color should not have
large change
The color should not have
large change
Qualified product
The color should not have
large change
Note: ① The limit of "soluble" metals in 0.07mol/L hydrochloric acid can be added with the limit of zinc in some cases. The test method for determining the "soluble" zinc content is specified in Article 5.2.9. If the user needs to add the limit of mercury, the test method can adopt the method specified in GB9758.7, or be agreed upon by the relevant parties.
② If the user needs to determine The arsenic or lead content of the pigment itself can replace the determination of arsenic or lead in hydrochloric acid solubles, and the determination method should be agreed upon by the relevant parties.
③ If the user has special requirements for technical indicators such as color, relative tinting strength, ease of dispersibility, oil absorption, thermal stability, etc., they can be negotiated separately. However, the inspection should be carried out according to the test methods specified in this standard.
HG2351-92
④ Standard samples of "color" and "relative tinting strength": Type I, Xiangtan Chemical Research and Design Institute: Type 1, Xiangtan Dye Chemical General Plant: Type I, Xiangtan Chemical Research and Design Institute, Shanghai Glass Sugar Chemical Plant. 5 Test methods
During the analysis process, all reagents used should be analytically pure reagents, and grade 3 water or corresponding water specified in GB6682 should be used. 5.1 Determination of total amount [cadmium (Cd) + zinc (Zn) + selenium (Se) + sulfur (S)] 5.1.1 Determination of zinc content
5.1.1.1 Principle
Dissolve the sample in hydrochloric acid and nitric acid, neutralize, add potassium cyanide, and titrate the alkaline earth metal with EDTA standard titration solution. Add formaldehyde solution to destroy the cadmium cyanide and zinc cyanide complexes, and titrate the total amount of cadmium ions and zinc ions with EDTA standard titration solution. In the titration solution, use sodium diethyldithiocarbamate to destroy the cadmium-EDTA complex, and precipitate cadmium with ammonia water, and titrate the EDTA originally complexed with cadmium with magnesium sulfate standard solution.
5.1.1.2 Reagents
5.1.1.2.1 Hydrochloric acid: 1.18g/mL.
5.1.1.2.2 Hydrochloric acid solution: dilute with 1.18g/mL hydrochloric acid, 1+115. 5.1.1.2.3
Nitric acid: 1.40g/mL.
5.1.1.2.4
Sodium hydroxide solution: 100g/L.
5.1.1.2.5
Ammonia water: 0.91g/mL.
Formaldehyde solution: 30% (m/m).
5.1.1.2.6
5. 1. 1. 2. 7
5.1.1.2.8
5.1.1.2.9
Ammonium chloride solution: 107g/L.
Sodium diethyldithiocarbamate.
Potassium cyanide.
Please pay extra attention: Potassium cyanide is a deadly drug. 5.1.1.2.10
EDTA standard titration solution: c(EDTA)=0.01molL. Accurately weigh 3.7223g of disodium ethylenediaminetetraacetate (C1oH14N20gNaz·2H20) and dissolve it in water, transfer it into a 1000mL volumetric flask, dilute it to the mark, and shake it well. 5.1.1.2.11 Magnesium sulfate standard solution: c(MgSO4)=0.01mol/L. Accurately weigh 2.4637g of magnesium sulfate (MgSO4·7H20) and dissolve it in hydrochloric acid solution (0.5+999.5), transfer it into a 1000mL volumetric flask, dilute it to the mark with the same hydrochloric acid solution, and shake it well. 2 Methyl orange solution: 0.1g/L.
5. 1. 1.2. 12
3 Eriochrome Black T Indicator. Mix 1g of Eriochrome Black T with 100g of ammonium chloride and grind until uniform. 5. 1. 1. 2. 13
5.1.1.2.14 Buffer Solution. Dissolve 70g of ammonium chloride in 774mL of ammonia water and dilute to 1000mL with water. 5.1.1.3 Instruments
General laboratory instruments and
5.1.1.3.1 Volumetric flask: 250mL, 1000mL. 5.1.1.3.2 Pipette: 25mL.
5.1.1.3.3 Burette: 50mL.
5.1.1.4 Operation steps
Perform parallel determination of two samples.
Weigh 0.3~0.4g of the sample (accurate to 0.0001g) and place it in a 250mL beaker, moisten the sample with a small amount of water, add about 10mL of hydrochloric acid (5.1.1.2.1), and heat carefully until the hydrochloric acid evaporates to dryness. Add 2mL of nitric acid (5.1.1.2.3) to the residue, cover the beaker with surface blood, and heat on an electric stove for 10min or until the solution is clear. Add 100mL of water and boil for 2~3min. If there is insoluble matter, filter it with dense filter paper. First wash with hydrochloric acid solution (5.1.1.2.2), then wash with water, collect the filtrate and washing liquid in a 250mL volumetric flask, dilute to scale and mix thoroughly.
HG2351—92
Pipette 25mL of the above solution, place in a 250mL beaker, dilute to 100mL with water, add 1~2 drops of methyl orange solution (5.1.1.2.12), neutralize with sodium hydroxide solution (5.1.1.2.4), add 2~3mL buffer solution (5.1.1.2.14), 0.25g of EDTA black T indicator (5.1.1.2.13) and about 2g of potassium cyanide (5.1.1.2.9). Titrate with EDTA standard titration solution (5.1.1.2.10) until the solution changes from red to blue.
Add about 20 mL of formaldehyde solution (5.1.1.2.6) to the obtained solution, and drop ammonium chloride solution (5.1.1.2.7) until the pH is 10-10.5. Titrate with EDTA standard titration solution (5.1.1.2.10) until the solution changes from red to blue. Record the volume of EDTA standard titration solution used for titration.
Add about 1 g of sodium diethyldithiocarbamate (5.1.1.2.8) and 2-3 drops of ammonia water (5.1.1.2.5) to the titrated solution, and titrate with magnesium sulfate standard solution (5.1.1.2.11) until the solution changes from blue to red. Record the volume of magnesium sulfate solution used for titration. 5.1.1.5 Expression of results
The mass percentage of cadmium is expressed as Wc and is calculated according to formula (1):Vicix0.1124×100
The mass percentage of zinc is expressed as Wying and is calculated according to formula (2): (V.V)X0. 065 4×100
_(V.-V)X0.654
Where.V.
-volume of EDTA standard titration solution, mL; V1-volume of magnesium sulfate standard solution, mL; c1-concentration of magnesium sulfate standard solution, mol/L; C2
-concentration of EDTA standard titration solution, mol/L;-mass of sample, g;
0.1124-mass of cadmium expressed in grams equivalent to 1.00mL magnesium sulfate standard solution [c(MgS04)=1.000mol/LJ 0.0654-
-mass of zinc expressed in grams equivalent to 1.00mLEDTA standard titration solution [c(EDTA）=1.000mol/LJ. The difference between the parallel determination results is not greater than 0.4%. The average value of the calculated samples is the determination result. 5.1.2 Determination of selenium content
5.1.2.1 Principle
Dissolve the sample in bromine water. After the bromine is driven out, use diamine hydrochloride to reduce and precipitate the selenium, and then weigh it. 5.1.2.2 Reagents and materials
5.1.2.2.1 Hydrochloric acid: 1.18g/mL.
5.1.2.2.2 Hydrochloric acid solution: dilute with 1.18g/mL hydrochloric acid, 1+115. 5.1.2.2.3 Bromine.
Diamine hydrochloride (H2N·NH2·2HCI). 5.1.2.2.4
Please pay extra attention: Diamine hydrochloride is a highly toxic substance. Carbon dioxide or nitrogen: compressed gas.
5.1.2.2.5
5.1.2.3 Instruments
General laboratory instruments and
HG2351—92
5.1.2.3.1 Conical flask: 100mL, ground stopper specification 18.8mm/19mm. 5.1.2.3.2 Straight condenser: 400mm in length, 13mm in inner diameter of upper and lower openings, ground stopper type at the lower end, specification 18.8mm/19mm.
5.1.2.3.3 Safety pipette: 1mL.
5.1.2.3.4 Water bath: can be maintained at 98±2℃. 5.1.2.3.5 Glass filter: pore size 7~8um. 5.1.2.3.6 Electric drying oven: can be maintained at 105±2℃. 5.1.2.3.7 Dryer: Contain effective desiccant. 5.1.2.4 Operation steps
Extra attention: All operations on bromine should be carried out in a ventilated kitchen and safety gloves should be used. Perform parallel determination of two samples.
Weigh about 0.5g of the sample (accurate to 0.0001g), place it in a 100mL conical flask with a ground glass stopper, suspend it in 10mL of water, add 1mL of bromine (5.1.2.2.3) with a safety pipette, cover the bottle stopper, and let it stand for at least 3 hours or overnight. Dilute the solution with about 20mL of water and install a straight condenser on the conical flask. Insert a glass tube with a pointed tip through the condenser near the bottom of the conical flask, and connect the glass tube to the gas source of carbon dioxide or nitrogen (5.1.2.2.5). Under slow heating, pass carbon dioxide or nitrogen into the solution until the bromine is completely driven out. Use potassium iodide-starch test paper to test bromine at the top of the condenser. Add 5 mL of hydrochloric acid (5.1.2.2.1) to the bromine-free solution. If there is insoluble matter, filter it with dense filter paper. First wash with hydrochloric acid solution (5.1.2.2.2), and then wash with hot water until there is no chloride. Add 20~30 mL of hydrochloric acid (5.1.2.2.1) to every 100 mL of filtrate and washing liquid. After the solution is cooled, add about 5 g of dihydrochloric acid hydrazine (5.1.2.2.4) and heat it on a water bath. When the red precipitate completely turns into a black state, filter it with a weighed glass filter and wash it with hot water. Combine the filtrate and washing liquid for the determination of sulfur content (see 5.1.3). Place the glass filter and the filter residue in an electric drying oven and dry them at 105℃ for 1 hour. Place it in a desiccator, cool it to room temperature, and weigh it (accurate to 0.0001g). Repeat the drying, cooling and weighing operations until constant weight is obtained. 5.1.2.5 Expression of results
The mass percentage of selenium is expressed as Ws and is calculated according to formula (3): Wse
Wherein, m1 is the mass of the sample, and
m2 is the mass of selenium, g.
m2×100
The difference between the results of parallel determinations shall not exceed 0.4%. The arithmetic mean is taken as the determination result. 5.1.3 Determination of sulfur content
The sulfur content determined by this method includes both sulfur in sulfides and sulfur in sulfates, but insoluble sulfates, such as sulfur in barium sulfate, are excluded.
5.1.3.1 Reagents
5.1.3.1.1 Ammonia water 0.91 g/mL.
5.1.3.1.2 Hydrochloric acid solution: dilute with 1.18g/mL hydrochloric acid, 1+12. 5.1.3.1.3 Chlorinated iodine solution: 100g/L. 5.1.3.1.4 Methyl orange solution: 0.1g/L. 5.1.3.2 Instruments
General laboratory instruments and
5.1.3.2.1 Porcelain: 30mL.
HG2351—92
5.1.3.2.2 Box-shaped resistance furnace: capable of maintaining at 800±25℃. 5.1.3.2.3 Dryer: filled with effective desiccant. 5.1.3.3 Operation steps
Perform parallel determination of two samples.
Add 5-6 drops of methyl orange solution (5.1.3.1.4) to the filtrate and washing liquid obtained when determining the selenium content in Article 5.1.2.4, neutralize with ammonia water (5.1.3.1.1), add 3-5 mL of hydrochloric acid solution (5.1.3.1.2) to every 100 mL of solution, heat to boiling, add about 15 mL of barium chloride solution (5.1.3.1.3) dropwise with stirring, and boil again. After the precipitate is precipitated (if necessary, it can be left to stand overnight.), filter with dense filter paper, wash the precipitate with hydrochloric acid solution (5.1.3.1.2) first, and then wash it with hot water. Place the filter paper and precipitate in a weighed porcelain amber, let in air, heat, and slowly ash the filter paper. Place the porcelain crucible and the residue in a box-shaped resistance furnace, heat to about 800°C, burn for 30 minutes, place in a dryer, cool to room temperature, and weigh. 5.1.3.4. Expression of results
The mass percentage of sulfur is expressed as Ws and is calculated according to formula (4): Ws-max13.74
Wherein: m1——mass of the sample, g;
m3—mass of barium sulfate, g;
13.74——the coefficient for converting BaSO4 to S multiplied by 100. The difference between the results of parallel determinations shall not exceed 0.4%. The arithmetic mean is taken as the determination result. 5.1.4 Calculation of total content of zinc, selenium and sulfur The total content of Cd, Zn, Se and S in the pigment, expressed as mass percentage Wtotal, is calculated according to formula (5): Wca+Wz+Wse+Ws
Wca——the cadmium content of the pigment determined according to 5.1.1; Wz——the zinc content of the pigment determined according to 5.1.1; Wse——the selenium content of the pigment determined according to 5.1.2; Ws——the sulfur content of the pigment determined according to 5.1.3. 5.2 Determination of soluble substances in 0.07 mol/L hydrochloric acid——antimony, arsenic, barium, cadmium, chromium, lead, selenium and zinc 5.2.1 Preparation of hydrochloric acid extraction solution
. (4)
(5)
Prepare the hydrochloric acid extraction solution of all metals in the cadmium red pigment sample, including lead, according to the operating steps described in Article 8.2.3 of GB9760. At the same time, prepare a blank test solution according to the operating steps described in Article 8.4 of GB6760. 5.2.2 Determination of "soluble" antimony content
Determine the "soluble" antimony content of the pigment sample according to the method described in Chapter 3 of GB9758.2 (flame atomic absorption spectrometry), and calculate the "mass m of soluble antimony in the hydrochloric acid extraction solution using formula (1) in Article 3.6.1.1 of GB9758.2. Multiply by 10/m, (m is the mass of the sample used to prepare the hydrochloric acid extraction solution, 5.00 ± 0.01g is used) to calculate the "soluble" antimony content of the pigment. 5.2.3 Determination of "soluble" arsenic content
Determine the "soluble" arsenic content of the pigment sample according to the method described in GB7686. 5.2.4 Determination of "soluble" barium content
5.2.4.1 Flame atomic emission spectrometry (arbitration method) The "soluble" barium content of the pigment sample is determined according to the method described in GB9758.3, and the mass m of "soluble" barium in the hydrochloric acid extraction solution is calculated using formula (1) in Article 7.1.1 of GB9758.3. Multiply by 10°/m (m is the mass of the sample used to prepare the hydrochloric acid extraction solution, and 5.00±0.01g is used) to calculate the *soluble barium content of the pigment. 5.2.4.2 Barium Sulfate Turbidimetric Method
5.2.4.2.1 Reagents
Hydrochloric acid: c(HCI)=0.07mol/L
Sulfuric acid: c(H,So,) is about 1mol/L;
HG2351-92
Lock standard solution: 100mg(Ba) per liter. In a 1000mL volumetric flask, dissolve 0.1779g of dihydrated chloride (BaCl2·2H20) in water, dilute to scale and mix thoroughly. This standard solution contains 100ug(Ba) in 1mL. 5.2.4.2.2 Instruments
General laboratory instruments and
Burette: 10mL;
Pipette: 10mL;
Colorimetric tube: 10mL;
Volume flask: 1000mL.
5.2.4.2.3 Operation steps
Preparation of standard turbidity solution
Use a burette to add 5 mL of hydrochloric acid and the volume of lock standard solution and water shown in Table 2 to 5 colorimetric tubes respectively. Table 2 Standard turbidity solution of barium
Standard turbidity solution
Volume of lock standard solution (5.2.4.2.1c) mL
Add 0.5 mL of sulfuric acid to each solution and mix thoroughly. b. Determination
Perform parallel determination of two samples.
Mass of barium in standard turbidity solution
Use a pipette to measure 1 mL, 2 mL, or 10 mL of the hydrochloric acid extraction solution prepared according to the operation steps described in Section 5.2.1, place it in a colorimetric tube, dilute it to 10 mL with hydrochloric acid, add 0.5 mL of sulfuric acid (5.2.4.2.1b), and mix thoroughly. Compare with the standard after 15 minutes. 5.2.4.2.4 Expression of results
The mass percentage of barium is expressed as W·s and calculated according to formula (6): Was
wherein. a-
the mass of barium in the hydrochloric acid extraction solution used is measured by the standard turbidity solution series of barium, ug; V1-the sum of the volumes of hydrochloric acid and ethanol used for extraction as described in Article 5.2.1 (77mL is used), mL; Vz-the volume of hydrochloric acid extraction solution used for determination (1mL, or 2mL, or 10mL is used), mL; -the mass of the sample used to prepare the hydrochloric acid extraction solution as described in Article 5.2.1 (5.00±0.01g is used), g. m
5.2.5 Determination of “soluble” cadmium content
5.2.5.1 Flame atomic absorption spectrometry (arbitration method) (6)
Determine the “soluble” cadmium content of the pigment sample according to the method described in Chapter 3 of GB9758.4 (flame atomic absorption spectrometry), and calculate the “soluble” cadmium content of the pigment by multiplying the mass mo of the “soluble” cadmium in the hydrochloric acid extraction solution by 10°/m (m4 is the mass of the sample used to prepare the hydrochloric acid extraction solution, which is 5.00±0.01g). 5.2.5.2 Complexometric titration
5.2.5.2.1 Principle
HG2351-92
Use EDTA standard titration solution to titrate the total amount of zinc ions, use sodium diethyldithiocarbamate to destroy the cadmium-EDTA complex in the titration solution, and use magnesium sulfate standard solution to titrate the EDTA that was originally complexed with cadmium. To titrate zinc, it is necessary to use EDTA standard titration solution to titrate the alkaline earth metal in another test solution, and calculate the zinc content by the difference in the volume of the consumed EDTA standard titration solution.
5.2.5.2.2 Reagents
Ammonia water: 0.91g/mL;
b. Sodium diethyldithiocarbamate;
Potassium cyanide solution: 65g/L;
Please pay extra attention: Potassium cyanide is a deadly drug. EDTA standard titration solution: c(EDTA)=0.01mol/L; d.
Magnesium sulfate standard solution: c(MgSO,)=0.01mol/L, preparation method see Section 5.1.1.2.11 of this standard; e.
f. Eriochrome black T indicator: preparation method see Section 5.1.1.2.13 of this standard; Methyl orange solution: 0.1g/L.
5.2.5.2.3 Instruments
Usually use second-class laboratory glassware, but in case of dispute, first-class instruments should be used. General laboratory instruments and
a. Pipette: 20mL;
b. Burette: 10mL.
5.2.5.2.4 Operation steps
Perform parallel determination of two samples.
Use a pipette to measure 20 mL of the hydrochloric acid extraction solution prepared according to the operating steps described in Section 5.2.1, place it in a conical flask, dilute it with water to 50 mL, add 1~2 drops of methyl orange solution (5.2.5.2.2g), neutralize it with ammonia water (5.2.5.2.2a), add 1 mL of ammonia water, and then add 0.25 g of chrome black T indicator (5.2.5.2.2f). Titrate with EDTA standard titration solution (5.2.5.2.2d) until the color changes from red to blue, then accurately add 3 mL of EDTA standard titration solution and shake well. Record the total volume of EDTA standard titration solution added. Then use magnesium sulfate standard solution (5.2.5.2.2e) to back titrate until a stable red color, and record the volume of magnesium sulfate standard solution used. Add about 1 g of sodium diethyldithiocarbamate (5.2.5.2.2b) and shake well. Titrate the released EDTA with magnesium sulfate standard solution (5.2.5.2.2e) until the color changes. Record the volume of magnesium sulfate standard solution used. Use a pipette to measure 20 mL of the hydrochloric acid extraction solution (5.2.1) used above, dilute it to 50 mL with water, add 1 to 2 drops of methyl orange solution (5.2.5.2.2g), neutralize it with ammonia water (5.2.5.2.2a), add 1 mL of ammonia water, and add 10 mL of potassium cyanide solution (5.2.5.2.2c) and 0.25 g of chrome black T indicator (5.2.5.2.2f). Titrate with EDTA standard titration solution until the color changes, and record the volume of EDTA standard titration solution used.
5.2.5.2.5 Expression of results
The mass percentage of cadmium is expressed as Wcas, calculated according to formula (7): VcX0.1124×100
V1V.X0.1124
The "soluble" zinc content of the pigment, Wyi·s, is expressed as the mass percentage of zinc, calculated according to formula (8): (7)
Wz·s-
HG2351—92
s+Vs+Ve)) ·c×0. 065 4×100Vama
V, (Vs-(V++Ve+Ve))X0. 065 4
Wherein: V1 is the sum of the volumes of hydrochloric acid and ethanol used for extraction as described in Section 5.2.1 (77 mL is used), mL; V2 is the volume of the hydrochloric acid and ethanol extraction solution used for determination (20 mL is used), mL; V is the total volume of the EDTA standard titration solution added dropwise to the test solution, mL; V4 is the volume of the magnesium sulfate standard solution used for titration before adding sodium diethyldithiocarbamate, mL; Vs is the volume of the magnesium sulfate standard solution used for titration after adding sodium diethyldithiocarbamate, mL; Ve is the volume of the EDTA standard titration solution used to titrate the solution treated with potassium cyanide. Volume, mL; ci——concentration of magnesium sulfate standard solution, mol/L; C2——concentration of EDTA standard titration solution, mol/L; m——mass of the sample used to prepare the hydrochloric acid extraction solution as described in Section 5.2.1 (5.00 ± 0.01 g is used), g; (8)
0.1124——mass of cadmium equivalent to 1.00 mL magnesium sulfate standard solution (c(MgSO4)=1.000 mol/L), expressed in grams; —mass of zinc equivalent to 1.00 mL EDTA standard titration solution [c(EDTA)=1.000 mol/L], expressed in grams. 0.0654-
5.2.6 Determination of "soluble" chromium content
Determine the "soluble" chromium content of the pigment sample according to the method described in GB9758.6. And use the formula (1) in Article 7.1 of GB9758.6 to calculate the mass m of the "soluble" chromium in the hydrochloric acid extraction solution. Multiply by 10/m (m is the mass of the sample used to prepare the hydrochloric acid extraction solution, which is 5.00±0.01g) to calculate the "soluble" chromium content of the pigment. 5.2.7 Determination of "soluble" lead content
Determine the "soluble" lead content of the pigment sample according to the method described in Chapter 3 of GB9758.1 (flame atomic absorption spectrometry). And use the formula (1) in Article 3.5.1.1 of GB9758.1 to calculate the "soluble" lead content in the hydrochloric acid extraction solution. The mass of "soluble" lead m. Multiply by 10/m4 (m4 is the mass of the sample used to prepare the hydrochloric acid extraction solution, 5.00±0.01g is used) to calculate the "soluble" lead content of the pigment. 5.2.8 Determination of "soluble" selenium content
5.2.8.1 Principle
After the colored complex formed by selenium and 3,3'-diaminobenzidine hydrochloride is extracted with toluene, the absorbance of the organic phase is determined by a spectrophotometer at a wavelength of 420nm.
5.2.8.2 Reagents
5.2.8.2.1 Formic acid solution: 100g/L.
Ammonia water: 0.91g/mL.
5.2.8.2.2
5.2.8.2.3 EDTA solution: 12 0g/L.
5.2.8.2.4 Perchloric acid: p is about 1.67g/mL. Nitric acid: p is about 1.40g/mL.
5.2.8.2.5
5.2.8.2.6 Metacresol purple solution, 1g/L: Take 0.1g metacresol purple and one sodium hydroxide, add 10mL water, dissolve with slight heat, cool to room temperature, and dilute to 100mL. 5.2.8.2.7 3,3'-Diaminobenzidine hydrochloride solution: 5g/L. 5.2.8.2.8 Toluene.
5.2.8.2.9 Sodium sulfate: calcine at 400℃ for 1~2h. 5.2.8.2.10 Selenium standard stock solution, containing 1g selenium (Se) per liter: Dissolve 1.0000g pure selenium powder in a minimum amount of nitric acid. Dissolve, place in a water bath and evaporate to dryness. Dissolve in water, transfer to a 1000mL volumetric flask, dilute to scale and mix thoroughly.
This standard stock solution contains 1mg selenium (Se) in 1mL. HG2351-92
5.2.8.2.11 Selenium standard solution, containing 10mg (Se) per liter: This solution should be prepared on the day of use.
Pipette 10mL of selenium standard stock solution into a 1000mL volumetric flask, dilute to scale and mix thoroughly. This standard solution contains 10ug selenium (Se) in 1mL.
5.2.8.3 Instruments
General laboratory instruments and
5.2.8.3.1 Spectrophotometer: Suitable for measurement at a wavelength of 420m, equipped with an absorption cell with a thickness of 50mm. 5.2.8.3.2 Water bath: Can be maintained at 100℃. 5.2.8.3.3 Pipette: 10mL.
5.2.8.3.4 Burette: 10mL.
5.2.8.3.5 Volumetric flask: 50mL and 1000mL. 5.2.8.3.6 Separatory funnel: 100mL.
5.2.8.4 Operation steps
5.2.8.4.1 Preparation of standard comparison solution
Use a burette to add the volume of the selenium standard solution (5.2.8.2.11) shown in Table 3 to 5 250mL conical flasks. Table 3 Selenium standard comparison solution
Standard comparison solution
Note: 1) Blank solution.
Volume of selenium standard solution (5.2.8.2.11) mL
Corresponding concentration of selenium in standard comparison solution
μg/mL
Add 3mL of perchloric acid (5.2.8.2.4) to each solution, heat and evaporate to a volume of 2mL, and cool to room temperature. Add 50mL of water, 5mL of ETA solution (5.2.8.2.3) and 2 drops of m-cresol violet solution (5.2.8.2.6), and add ammonia water (5.2.8.2.2) until the color turns yellow. Then add 2mL of formic acid solution (5.2.8.2.1) and 2mL of 3,3-diaminobenzidine hydrochloride solution (5.2.8.2.7), mix well. Place in a boiling water bath and heat for 5min, remove, and cool to room temperature. Add ammonia water (5.2.8.2.2) until the color turns purple. Transfer the solution to a separatory funnel and extract with 20 mL of toluene (5.2.8.2.8) for 30 seconds. Transfer the organic phase to a 50 mL volumetric flask and dry with 3 g of sodium sulfate (5.2.8.2.9).
5.2.8.4.2 Spectrophotometric measurement
Use a spectrophotometer at a wavelength of 420 nm and use the toluene (5.2.8.2.8) in the reference cell as a reference to measure the absorbance of each standard comparison solution. Before each measurement, rinse the absorption cell with the standard comparison solution and subtract the absorbance of the blank solution from the absorbance of each standard comparison solution.
5.2.8.4.3 Plotting the standard curve
Plot a standard curve with the concentration of selenium in the standard comparison solution (in g/mL) as the horizontal axis and the corresponding absorbance value as the vertical axis. If the operating steps are followed accurately, this standard curve should be a straight line. 5.2.8.4.4 Determinationwww.bzxz.net
Carry out parallel determination of two samples.
Use a pipette to measure a certain volume of the hydrochloric acid extraction solution and the blank test solution prepared according to the operating steps described in Section 5.2.1 and place them in a 10
HG2351-92
250mL conical flask. The volume of the hydrochloric acid extraction solution taken should be such that its absorbance value is within the range of the standard curve. Add 10mL nitric acid (5.2.8.2.5) and 4mL perchloric acid (5.2.8.2.4), heat and evaporate to a volume of 2mL. Treat the solution according to the operating steps of Section 5.2.8.4.1. Then measure the absorbance value according to the operating steps of Section 5.2.8.4.2. 5.2.8.5 Expression of results
The mass percentage of selenium is expressed as Ws·s and is calculated according to formula (9): 20(a1-ao)X10-6
_20(a1-ao)·V1×10-4
V2·m4
Wherein: ao——the concentration of selenium in the blank comparison solution measured from the standard curve, g/mL; a
——the concentration of selenium in the sample comparison solution measured from the standard curve, g/mL; V1——the concentration of selenium in the sample comparison solution measured from the standard curve, g/mL;1 - the sum of the volumes of hydrochloric acid and ethanol used for extraction (77 mL is used), mL; V2 - the volume of the hydrochloric acid and ethanol extraction solution used for determination, mL; 20 - the volume of toluene used to extract the organic phase in the determination (20 mL is used), mL; m - the mass of the sample used to prepare the hydrochloric acid extraction solution described in 5.2.1 (5.00 ± 0.01 g is used), g. 5.2.9 Determination of "soluble" zinc content
5.2.9.1 Flame atomic absorption spectrometry (arbitration method) (9)
The test solution is drawn into an acetylene-air flame and the absorption of the selected spectral line emitted by a zinc hollow cathode lamp or a zinc electrodeless discharge lamp is measured at a wavelength of 213.9 nm.
5.2.9.1.1 Reagents and materials
Hydrochloric acid: c(HCI)=0.07mol/L;
Acetylene: for industrial use, packed in a steel cylinder;
c. Compressed air;
d. Zinc standard stock solution: contains 1g zinc (Zn) per liter. In a 1000mL volumetric flask, dissolve 4.3980g zinc sulfate heptahydrate (ZnSO, ·7H2O) in hydrochloric acid, dilute to the mark with the same hydrochloric acid and mix thoroughly. This standard stock solution contains 1mg zinc (Zn) per mL; e. Zinc standard solution: contains 10mg zinc (Zn) per liter. This solution should be prepared on the day of use. Transfer 10mL of zinc standard stock solution to a 1000mL volumetric flask, dilute to the mark with hydrochloric acid and mix thoroughly. This standard solution contains 10ug zinc (Zn) per mL. 5.2.9.1.2 Instruments
Usually, second-class laboratory glassware is used, but in case of dispute, first-class instruments should be used. General laboratory instruments and
Flame atomic absorption spectrometer: suitable for measuring at a wavelength of 213.9nm, and equipped with a combustion chamber that can pass acetylene and air a.
Zinc hollow cathode lamp or zinc electrodeless discharge lamp; b.
Pipette: 10mL;
Burette: 10mL;
e. Volumetric flask: 100mL and 1000mL.
5.2.9.1.3 Operating steps
a. Preparation of standard reference solution
Use a burette to add the volume of zinc standard solution (5.2.9.1.1e) shown in Table 3 to 7 100mL volumetric flasks, dilute to the mark with hydrochloric acid (5.2.9.1.1a) and mix thoroughly. b. Spectral measurement
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