GB/T 5451-2001 Determination of wettability of pesticide wettable powders

This standard specifies the determination of wettability of pesticide wettable powders. GB/T 5451-2001 Determination of wettability of pesticide wettable powders GB/T5451-2001 Standard download decompression password: www.bzxz.net

GB/T54512001
This standard is a revised version of GB/T5451--1985 "Determination of wettability of pesticide wettable powders". In terms of technical content, it is equivalent to the CIPAC method MT53.3 "Wettability evaluation of wettable powders" of the International Cooperative Committee for Pesticide Analysis. The main technical differences between this standard and the CIPAC method MT53.3 are: 1. The "MT53.3.1 non-shaking" method is used to determine the wetting time of wettable powders, while the "MT53.3.2 shaking" method is not used to determine the "shaking wetting time". Because the determination of the wettability of pesticide wettable powders in the pesticide specifications of FAO (Food and Agriculture Organization of the United Nations) and WHO (World Health Organization) only uses MT53.3.1, but not MT53.3.2; in order to align with international standards, this standard also only uses MT53.3.1.
2 The inverted sample method is specifically specified.
3 The purity of calcium carbonate and magnesium oxide reagents was changed from more than 99% in the CIPAC method to analytical pure. The main differences between this standard and GB/T5451---1985 are: 1 "Foreword" and "Scope" are added.
2 The units used in the standard are unified and changed to national legal measurement units. 3 Other preparation methods of standard hard water are added. Appendix A of this standard is the appendix of the standard.
This standard replaces GB/T5451-1985 "Determination of Wettability of Pesticide Wettable Powders" from the date of implementation. This standard is proposed by the State Bureau of Petroleum and Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the National Pesticide Standardization Technical Committee. The drafting unit of this standard: Shenyang Chemical Industry Research Institute. The main drafter of this standard: Zhang Xuebing.
This standard is the first revision. GB/T5451-1985 "Determination of Wettability of Pesticide Wettable Powders" was first issued in 1985. The Secretariat of the National Technical Committee for Standardization of Pesticides is responsible for the interpretation of this standard. 619
1 Scope
National Standard of the People's Republic of China
Testing method for the wettability ofdispersible powders of pesticidesThis standard applies to the determination of the wettability ofdispersible powders of pesticides. 2 Summary of the method
GB/T 5451-2001
Replaces GB/T5451—1985
Pour a certain amount of wettable powder from a specified height into a beaker containing a certain amount of standard hard water, and measure the time it takes for it to be completely wetted. 3 Instruments and equipment
Volume flask: 100mL, 1000ml;
Pipette: 10mL;
Polyethylene bottle: 1000mL;
Thermometer: graduation value 1℃, range 0℃~50℃ or 0℃~100℃; Beaker: 250mlL (inner diameter 6.5cm±0.5cm, height 9.0cm±0.5cm) 100ml800mL, 1000ml; Stopwatch;
Measuring cylinder: 20mL, 100mL±1mL, 500ml; Surface blood (diameter 9.0cm±0.5cm); Constant temperature water bath;
pH meter.
4 Reagents and solutions
Calcium carbonate: Bake at 400℃ for 2h before use; Magnesium oxide: Bake at 105℃ for 2h before use; Anhydrous calcium chloride;
Magnesium chloride with crystal water (MgClz·6H,O); Ammonia water: c(NH·H,O)=1 mol/L solution; Hydrochloric acid: c(HCI)=2mol/L solution, c(HCI)=1. 0 mol/L solution and c(HCI)=0. 1 mol/L solution; Methyl red: p(methyl red)=5g/L solution; Sodium hydroxide: c(NaOH)-0.1 mol/L solution. 5 Preparation of standard hard water [p(Ca2++Mg?+）=342mg/L] The following three methods can be selected.
5.1 Preparation method -
Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on July 13, 2001 620
Implemented on February 1, 2002
5.1.1 Preparation of stock solution
GB/T 5451---2001
5.1.1.1 Preparation of solution A - c(Ca2+) = 0.04 mol/L solution Accurately weigh 4.000 g of calcium carbonate, place it in an 800 ml beaker, add a small amount of water to moisten it, then slowly add 82 mL of 1.0 mol/L hydrochloric acid, stir and mix thoroughly, and after the calcium carbonate is completely dissolved, add 400 mL of water, boil and remove carbon dioxide. After cooling to room temperature, add 2 drops of methyl red indicator solution, neutralize it with 1 mol/L ammonia water to orange, transfer this solution to a 1000 mL volumetric flask, make up to volume with water, and shake well. Store in a polyethylene bottle for later use.
5.1.1.2 Preparation of Solution B -c(Mg2+)=0.04mol/L Solution Accurately weigh 1.613g of magnesium oxide, put it in an 800mL beaker, add a small amount of water to moisten it, then slowly add 82mL of 1.0mol/L hydrochloric acid, stir and mix thoroughly and slowly heat. After the magnesium oxide is completely dissolved, add 400mL of water, boil it, and remove carbon dioxide. After cooling to room temperature, add 2 drops of methyl red indicator solution, neutralize it with 1mol/L ammonia water to orange, transfer this solution to a 1000mL volumetric flask, make up to volume with water, and shake well. Store in a polyethylene bottle for later use. 5.1.2 Preparation of standard hard water
Pipette 68.5mL solution A and 17.0mL solution B into a 1000mL beaker, add 800mL water, drop 0.1mol/l sodium hydroxide solution or 0.1mol/L hydrochloric acid solution, and adjust the pH value of the solution to 6.0~7.0 (using a pH meter). Transfer the solution to a 1000ml volumetric flask, dilute to volume with water, and shake well.
5.2 Preparation method 2
Weigh 0.304g anhydrous calcium chloride and 0.139g magnesium chloride with crystal water, dissolve in 600ml water in a 1000mL beaker, and pour into a 1000ml volumetric flask. Rinse the beaker with 300mL water several times, pour the rinse solution into the volumetric flask, dilute to volume with water, and shake well.
5.3 Preparation method three
Weigh 2.740g of calcium carbonate and 0.276g of magnesium oxide, dissolve them in a 100mL beaker with a small amount of 2mol/L hydrochloric acid, and heat on a water bath to evaporate to dryness to remove excess hydrochloric acid. Then dissolve the residue with 60mL of water and pour it into a 100mL volumetric flask. Rinse the beaker with 30mL of water several times, pour the rinse liquid into the volumetric flask, make up the volume with water, and shake it well. Use a 10mL pipette to accurately draw 10mL, inject it into a 1,000mL volumetric flask, make up the volume with water, and spread it evenly. 6 Determination steps
Take 100mL±1mL of standard hard water, inject it into a 250mL beaker, and place the beaker in a constant temperature water bath at 25℃±1℃ so that the liquid level is flush with the horizontal surface of the water bath. When the hard water reaches 25℃±1℃, weigh 5g±0.1g of the sample (the sample should be a representative uniform powder, and no agglomeration or caking is allowed), place it on surface III, and pour all the samples evenly at once on the liquid surface of the beaker from a position flush with the mouth of the beaker, but do not disturb the liquid surface excessively. Use a stopwatch to record the time immediately after adding the sample until the sample is completely wetted (the fine powder film left on the liquid surface can be ignored). Record the wetting time (accurate to seconds). Repeat this 5 times, and take the average value as the wetting time of the sample. 621
A1 Reagents and solutions
Ammonium chloride;
Concentrated ammonia water;
GB/T 5451—2001
Appendix A
(Appendix recommended by the standard)bZxz.net
Determination method of total hardness of hard water
Buffer solution (pH=10): weigh 67.5g ammonium chloride and 570mL concentrated ammonia water, dilute to 1L with distilled water, and mix well; Acid chrome blue R;
Naphthol green;
Potassium sulfate;
Calcium-magnesium mixed indicator: weigh 1.0g acid chrome blue R, 2.0g naphthol green and 100.0g potassium sulfate, put them in an agate mortar, grind them finely and mix well, and store them in a brown bottle to prevent water absorption and light exposure; EDTA Disodium;
Pure zinc (or zinc oxide);
Concentrated hydrochloric acid;
Methyl orange;
Preparation of disodium EDTA standard titration solution: weigh 7.44g disodium EDTA, dissolve it in distilled water and dilute to 1000mL. Standardization of disodium EDTA standard titration solution: weigh about 0.016g pure zinc (or 0.024g zinc oxide), accurate to 0.00002g, dissolve in concentrated hydrochloric acid, use methyl orange as an indicator, and neutralize with concentrated ammonia water to neutrality. Add 1mL of buffer solution, add about 0.1g of calcium-magnesium mixed indicator, and titrate with disodium EDTA solution until it turns grass green. Perform a blank test under the same conditions. The concentration of disodium EDTA standard titration solution c(disodium EDTA) is calculated according to formula (A1) or formula (A2): c(disodium EDTA) = (V,- V)× 32. 69m2
Where: m,~--mass of pure zinc, mg;
m mass of zinc oxide, mg;
c(disodium EDTA) = (V,-V)× 48. 69m2
V,--volume of disodium EDTA standard titration solution consumed by the sample, mL; V. —Blank consumption of disodium EDTA standard titration solution volume, mL; 32.69 (1/2) Zn molar mass, g/mol; 48.69 --- (1/2) ZnO molar mass, g/mol. A2 Determination of total hardness of hard water
Transfer 25.00mL of water sample into a conical flask, add 1mL of buffer solution and about 0.1g of calcium-magnesium mixed indicator, and titrate with disodium EDTA standard titration solution until the pure blue color remains unchanged, which is the end point. Perform a blank test under the same conditions. The total hardness of hard water c (calculated as CaCO, g/L) is calculated according to formula (A3): 622
GB/T 5451--2001
c(CaCO.) = c(Disodium EDTA): (V- Vo) × 50. 0525.00
Wherein: c(Disodium EDTA)——Concentration of disodium EDTA, mol/L; V
Volume of standard disodium EDTA titration solution consumed by the sample, mL; V. —Volume of standard disodium EDTA titration solution consumed by the blank, mL; 50.05-—Molar mass of (1/2)CaCO3, g/mol. (A3)
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