GB/T 14825-1993 Determination of suspension rate of wettable powders of pesticides
Some standard content:
UDC632.939.1：543.275
National Standard of the People's Republic of China
GB/T14825-93
Determination method of suspensibility of wettable powders for pesticides1993-12-30Promulgated
State Administration of Technical Supervision
1994-10-01Implementation
1Scope of application
National Standard of the People's Republic of China
Determination method of suspensibility of wettable powders for pesticides This method is applicable to the determination of suspension rate of wettable powder of pesticides 2 Reference standards
GB601 Preparation of standard solution for titration analysis of chemical reagents (volume analysis) GB603 Preparation of preparations and products used in test methods of chemical reagents 3 Determination of suspension rate
3.1 Method 1 (arbitration method)
GB/T14825-93
3.1.1 Method summary: Prepare the sample to be tested into a suspension of appropriate concentration using standard hard water. Under the specified conditions, let it stand in a measuring cylinder for 30 minutes, determine the content of active ingredients in the bottom tenth of the suspension, and calculate its suspension rate. 3.1.2 Reagents
The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and grade 3 water specified in GB6682. 3.1.2.1 Magnesium oxide (GB9857): Dry at 105℃ for 2h before use; 3.1.2.2 Calcium carbonate (HG31066): Dry at 400℃ for 2h before use; 3.1.2.3 Hydrochloric acid (GB622) solution: 0.1mol/L, 1mol/L 3.1.2.4 Sodium hydroxide (GB629) solution: 0.1mol/L 3.1.2.5 Ammonia water (GB631): 1mol/L L,
3.1.2.6 Methyl red (HG3-958) indicator solution: 1g/L, prepared according to GB6034.5.6 3.1.2.7 Preparation of solution: A, B are prepared as follows: A solution: c (Ca2+) = 0.04mol/L
Accurately weigh 4.000g of calcium carbonate in an 800mL beaker, add a small amount of water to moisten, slowly add 82mL of 1mol/L hydrochloric acid solution, and stir well. After the calcium carbonate is completely dissolved, add 400mL of water, boil, remove carbon dioxide, cool to room temperature, add 2 drops of methyl red indicator solution, neutralize with ammonia water to orange, transfer this solution to a 1000mL volumetric flask, dilute with water to the scale, and mix well. Store in a polyethylene bottle for later use. Solution B: c(Mg2+)=0.04mol/L
Accurately weigh 1.613g of magnesium oxide, place in an 800mL beaker, add a small amount of water to moisten, slowly add 82mL of 1mol/L hydrochloric acid solution, stir thoroughly and slowly heat, after the magnesium oxide is completely dissolved, add 400mL of water, boil, and remove carbon dioxide. Cool to room temperature, add 2 drops of methyl red indicator solution, neutralize with ammonia water to orange, transfer this solution to a 1000mL volumetric flask, dilute with water to the scale, and mix well. Store in a polyethylene bottle for later use.
3.1.2.8 Standard hard water: Calculated as calcium carbonate, 342 mg/L, the preparation method is as follows: Approved by the State Bureau of Technical Supervision on December 30, 1993, implemented on October 1, 1994
GB/T14825-93
Pipette 68.5 mL of A solution and 17.0 mL of B solution into a 1000 mL beaker, add 800 mL of water, drop 0.1 mol/L sodium hydroxide solution or 0.1 mol/L hydrochloric acid solution, and adjust the pH to 6.0-7.0 (measured by pH meter). Transfer the solution into a 1000 mL volumetric flask, dilute to the mark with water, and mix well. 3.1.3 Instruments
3.1.3.1 Measuring cylinder: 250mL, with ground glass stopper, 0~250mL scale interval is 20.0~21.5cm, the distance between the 250mL scale line and the bottom of the stopper should be 4~6cm;
3.1.3.2 Glass pipette: about 40cm long, inner diameter about 5mm, with a hole of about 2~3mm at the tip of one end, and the other end of the tube is connected to the corresponding vacuum source;
3.1.3.3 Constant temperature water bath: 30±1℃
3.1.3.4 Stopwatch.
3.1.4 Determination steps
Weigh an appropriate amount of sample D, accurate to 0.0001g, and place it in a 200mL beaker filled with 50mL standard hard water (30±1℃). Shake it in a circular motion by hand, about 120 times per minute, for 2 minutes. Place the suspension in a water bath at the same temperature for 13 minutes, then wash it all into a 250mL measuring cylinder with 30±1℃ standard hard water, and dilute to the scale. Cover the stopper, and with the bottom of the measuring cylinder as the axis, turn the measuring cylinder upside down 30 times within 1 minute (turning the measuring cylinder upside down and returning it to its original position is one time, about 2 seconds). Open the stopper, and then place it vertically in a vibration-free constant temperature water bath and place it for 30 minutes. Use a pipette to remove 9/10 (i.e. 225mL) of the suspension in 10~15 seconds. Do not shake or stir up the sediment in the measuring cylinder, and ensure that the top of the pipette is always a few millimeters below the liquid surface. According to the prescribed method 2), determine the active ingredient content in the sample and the 25 mL suspension remaining at the bottom of the measuring cylinder. Note: 1) The concentration of the suspension prepared with this sample should be the highest spray concentration recommended for the wettable powder. The sample weight is specified in the product standard.
2) The determination of the active ingredient content should be specified in the product standard. 3.1.5 Calculation
The sample suspension rate X [% (m/m) is calculated according to formula (1): x1=10/9×ml=m2×100bzxz.net
Where: m1——the mass of the active ingredient in the sample taken to prepare the suspension, g; m2——the mass of the active ingredient in the 25 mL suspension remaining at the bottom of the measuring cylinder, g. 3.2 Method 2
3.2.1 Method Summary
· (1)
Use standard hard water to prepare a suspension of the sample to be tested into a suspension of appropriate concentration. Under the specified conditions, let it stand in a measuring cylinder for 30 minutes. Determine the content of the effective ingredient in the upper nine-tenths of the suspension in the measuring cylinder and calculate the suspension rate of the sample. 3.2.2 Reagents
Same as 3.1.2.
3.2.3 Instruments
Same as 3.1.3.
3.2.4 Determination Steps
Weigh an appropriate amount of sample 1) to an accuracy of 0.0001g and place it directly in a measuring cylinder containing 50mL of standard hard water (30±1℃). Gently vibrate to disperse the sample, then dilute it to the scale with 30±1℃ standard hard water and cover it with a stopper. With the bottom of the measuring cylinder as the axis, turn the measuring cylinder upside down 30 times within 1 minute (turning the measuring cylinder upside down and returning it to its original position is one time, about 2 seconds). Open the stopper and place it vertically in a non-vibrating constant temperature water bath, avoid direct sunlight, and leave it for 30 minutes. Use a pipette to transfer 9/10 (i.e. 225mL) of the suspension to a clean 500mL conical flask within 10 to 15 seconds. Do not shake or stir the sediment in the measuring cylinder, and ensure that the top of the pipette is always a few millimeters below the liquid surface. 2
GB/T14825—93
After fully shaking the 225mL suspension in the conical flask, quickly transfer a certain volume (VmL) of test solution to determine the active ingredient content therein or determine the active ingredient content in the bottom 25mL suspension and sediment2). Note: 1) The concentration of the suspension prepared with this sample should be the highest spray concentration recommended for the wettable powder. The sample weight shall be specified in the product standard.
2) The determination of the content of the active ingredient shall be specified in the product standard. 3.2.5 Calculation
3.2.5.1 When determining the upper 225mL suspension, the sample suspension rate X[% (m/m) shall be calculated according to formula (2): Xz = 250×m2×100
Where: V—the volume of the suspension used for analysis, mL, mr—the mass of the active ingredient in the sample taken to prepare the suspension, g; mr
-VmL the mass of the active ingredient in the suspension, g; m2
250——the total volume of the prepared suspension, mL. 3.2.5.2 When determining the bottom 25mL suspension, the sample suspension rate shall be calculated according to formula (1) in 3.1.5. *******.(2)
A1 Reagents and solutions
GB/T14825—93
Appendix A
Method for determination of hard water
(Supplement)
A1.1 Ammonia-ammonium chloride buffer solution A: pH~10, prepared according to GB6034.4.8; A1.2 Eriochrome black T indicator solution: 5g/L, prepared according to GB6034.5.24; A1.3 Ethylenediaminetetraacetic acid disodium standard solution: c (EDTA) = 0.01mol/L, prepared and calibrated according to GB6014.15. A2 Determination of total hardness
Accurately transfer 25mL of water sample into a conical flask, add 10mL of ammonia-ammonium chloride buffer solution A (pH~10) and 5 drops of chromium black T indicator solution (5g/L), and titrate with ethylenediaminetetraacetic acid disodium standard titration solution until the solution changes from purple to pure blue. Perform a blank test at the same time. Total hardness (calculated as calcium carbonate, unit: mg/L) is calculated according to formula (A1): Vo)×0.1001×10%
Total hardness 2
Wherein: c
actual concentration of disodium ethylenediaminetetraacetic acid standard titration solution, mol/L-the volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed by titrating the sample solution, mL, Vi
V. —the volume of disodium ethylenediaminetetraacetic acid standard titration solution consumed by titrating the blank solution, mL, 25.00 —the volume of hard water transferred, mL, 0.1001-
. (A1)
-the mass of calcium carbonate in grams equivalent to 1.00mL disodium ethylenediaminetetraacetic acid standard titration solution [c(EDTA)=1.000mol/L.
Appendix B
Adoption statement
(reference)
This standard method 1 is equivalent to the FAO (Food and Agriculture Organization of the United Nations) standard, namely CIPAC (International Cooperative Committee for Pesticide Analysis) MT15.1.
The difference is:
The purity of the two reagents, calcium carbonate and magnesium oxide, is changed from the original method to more than 99% to analytical purity. B2 After preparing the suspension, keep the temperature constant for 30 minutes with the stopper of the measuring cylinder opened. CIPACMT15.1 method does not make specific provisions on whether to open the stopper.
Additional remarks:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard was drafted and technically coordinated by Shenyang Chemical Industry Research Institute. The main drafters of this standard were Lou Shaowei and Gao Xiaohui. Method 1 in this standard is equivalent to the International Cooperative Committee for Pesticide Analysis standard CIPACMT15.1 "Suspension of Water-dispersible Powders 15.1" (1970).
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