Some standard content:
National Standard of the People's Republic of China
Dimethoate emulsifiable concentrate
40% Dimethoate emulsifiable concentratesSubject content and scope of application
GB15583—1995
This standard specifies the technical requirements, test methods, inspection rules, and requirements for marking, packaging, transportation and storage of dimethoate emulsifiable concentrate. This standard applies to the emulsifiable concentrate prepared by dissolving dimethoate technical and emulsifier in a suitable solvent. Cited standards
GB/T601
GB/T1600
GB/T1603
GB/T1604
GB/T1605
GB3796
GB4838
Technical conditions
Chemical reagents
Preparation of standard solution for titration analysis (volume analysis)Determination of moisture content in pesticides
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Emulsifiable concentrate pesticide packaging
Appearance: This product should be a homogeneous liquid. If crystals are found due to low temperature storage, place this product at 20℃ for 24h and it should return to its original state after shaking.
Dimethoate EC shall also meet the following requirements: Item
Dimethoate content, %(m/m)
Water content, %(m/m)
Acidity (in H2SO4), %(m/m)
Emulsion stability (diluted 200 times)
Low-energy stability"
Hot storage stability \
Note: 1) Test at least once every six months.
Test method
Unless otherwise specified, the reagents used in this test are analytically pure and the water used shall meet the third-grade water specifications in GB/T6682. Approved by the State Bureau of Technical Supervision on June 12, 1995 and implemented on February 1, 1996
4.1 Test method of Dimethoate EC
GB15583—1995
4.1.1 Identification test
When there is doubt about the identification of the active ingredient using the prescribed test method, at least another method shall be used for identification. Gas chromatography: This identification test can be carried out simultaneously with the determination of the content of dimethoate. The relative deviation between the retention time of the main peak of the sample solution and the retention time of dimethoate in the standard solution under the same conditions should be within 1.5%. Infrared spectroscopy: There should be no obvious difference between the infrared absorption spectrum of the active ingredient separated from the sample and the standard. T100f
4.1.2 Determination of dimethoate content
4.1.2.1 Gas chromatography
Figure 1 Infrared harmonic spectrum of dimethoate standard
400 cm
4.1.2.1.1 Method Summary
The sample was dissolved in acetone, and n-tricosane (or di-n-pentyl terephthalate) was used as the internal standard. A glass column filled with 3% OV-17/Chromosorb W-HP and a hydrogen flame ionization detector were used to separate and determine the dimethoate emulsifiable concentrate by gas chromatography. 4.1.2.1.2 Reagents and Solutions
Solvent: acetone (GB/T686);||t t||Dimethoate standard: known content ≥ 99.0% (m/m); internal standard: n-tricosane (or di-n-pentyl terephthalate), should not contain impurities that interfere with analysis; stationary phase: OV-17
Carrier: ChromosorbW-HPDMCS, 180~250μm. Internal standard solution: weigh 0.56g of n-tricosane or 0.8g of di-n-pentyl terephthalate) and place in a 100mL volumetric flask, add acetone to dissolve, and Dilute to the mark and shake well. Tighten the stopper and store at room temperature. 4.1.2.1.3 Instruments
Gas chromatograph: with FID detector;
Chromatographic column: 1mX2mm (id) glass column;
GB15583--1995
Column filling: OV-17 coated on Chromosorb W-HPDMCS (180～250μm). Stationary liquid: carrier = 3:1 00(m/m)
Chromatographic processor
Glass wool: Silanized
4:1.2.1.4 Preparation of chromatographic column
a. Coating of stationary liquid
Accurately weigh 0.060g OV-17 stationary liquid into a 250mL beaker, add an appropriate amount (slightly larger than the volume of the carrier) of trifluoromethane to completely dissolve it, pour in 2.0g of the carrier, shake gently to mix it evenly and evaporate the solvent to near dryness. Then place the beaker in an oven at 110℃ for 1h, take it out and place it in a desiccator to cool to room temperature before loading it into the column. b. Filling of chromatographic column
Connect a funnel to the outlet of the washed and dried chromatographic column, fill the prepared filler into the column in batches, and tap the column wall continuously until it is filled to 1.5cm from the column outlet. Move the funnel to the entrance of the chromatographic column, plug a small ball of silanized glass wool at the outlet, connect it to the vacuum pump through a rubber tube, turn on the vacuum pump, continue to slowly add the filler, and tap the column wall continuously to make it evenly filled. After filling, plug a small ball of glass wool at the entrance and press it properly to prevent the column filler from moving. c. Aging of the chromatographic column
Connect the entrance of the chromatographic column to the vaporization chamber, do not connect the detector at the outlet, and pass the carrier gas (N2) at a flow rate of 20mL/min, raise the temperature to 230℃ in stages, and age at this temperature for at least 48h. d.
Passivation of chromatographic column
After the aging of the chromatographic column is completed, the column temperature is lowered to about 140℃, and a 50μL syringe is used to inject 5% (or 10%) dimethyldichlorosilane toluene solution (or other silanization reagent) into the vaporization chamber, 20μL each time, 30min interval, 8 times in total, and finally stay for at least 2h. After the passivation is completed, connect the column outlet to the detector. 4.1.2.1.5 Gas chromatography operating conditions
Temperature: column chamber, 160℃; vaporization chamber, 200℃; detector chamber, 250℃. Gas flow rate: carrier gas (N, preferably high-purity nitrogen) 30mL/min; hydrogen, about 30mL/min; air, about 300mL/min; retention time: dimethoate, about 3.6min; n-tricosane, about 9.7min (di-n-pentyl terephthalate, about 8.7min). The above operating conditions are typical operating parameters. According to the characteristics of different instruments, the given operating parameters can be appropriately adjusted to obtain the best effect.
GB15583-1995
Figure 2 Gas chromatogram of dimethoate emulsifiable concentrate (with n-tricosane) 1-Solvent (acetone); 2-Dimethoate; 3-Internal standard (n-tricosane) Figure 3 Gas chromatogram of dimethoate emulsifiable concentrate (with di-n-pentyl terephthalate) 1 Solvent (acetone); 2-Dimethoate; 3-Internal standard (di-n-pentyl terephthalate) 4.1.2.1.6 Determination steps
Preparation of standard solution
GB15583-1995
Weigh about 0.1g (accurate to 0.0002g) of dimethoate standard sample, place it in a stoppered glass bottle, accurately transfer 5mL of internal standard solution with a pipette, and spread it evenly.
Preparation of sample solution
Weigh a sample containing about 0.1g of dimethoate (accurate to 0.0002g), place it in a stoppered glass bottle, accurately transfer 5mL of internal standard solution with a pipette, and shake well.
Under the selected chromatographic conditions, after the instrument baseline is stable, repeatedly inject the standard solution, calculate the repeatability of the relative response value of each needle, and when the relative response value of two adjacent needles changes less than 1.5%, perform gas chromatography analysis in the following order: standard solution; sample solution; sample solution; standard solution. 4.1.2.1.7 Calculation
Average the ratio of the peak area of dimethoate to the internal standard in the two needles of sample solution and the two needles of standard solution before and after the sample. The mass percentage content of dimethoate X, is calculated according to formula (1): X, = Tm, P
Wherein: \--the average value of the peak area ratio of dimethoate to the internal standard in the standard solution; :--the average value of the peak area ratio of dimethoate to the internal standard in the sample solution; m--the mass of the dimethoate standard, g;
m2--the mass of the sample, gt
P--the content of the dimethoate standard, % (m/m). 4.1.2.1.8 Allowable difference
The difference between the results of two parallel determinations should not exceed 0.8%. Take the average value and report it as the result. 4.1.2.2 Thin layer-desolidification method (arbitration method) 4.1.2.2.1 Summary of the method
The sample is subjected to thin layer chromatography to separate the dimethoate from impurities, scrape off the spectrum band containing dimethoate, and then determine it by desolidification method. 4.1.2.2.2 Reagents and solutions
Anhydrous ethanol (GB/T678);
Potassium bromate
Potassium bromide
Potassium iodide
(GB/T686);
(GB/T690);
(GB/T650);
(GB/T649)
(GB/T1272): 30% aqueous solution;
Sulfuric acid (GB/T625) solution: 1+4 (V/V). Take 1 part of sulfuric acid and slowly add it to 4 parts of water under stirring, let it cool for later use; (1)
Potassium bromate-potassium bromide solution: c(1/6KBrO,)=0.15mol/L. Weigh 4.2g potassium bromate and 40g potassium bromide, dissolve in 1000mL water, spread evenly;
sodium thiosulfate (GB/T637) standard titration solution: c(Na,S,0,)=0.1mol/L; palladium fluoride indicator solution: 1g/L. Weigh 0.1g chloride, dissolve in 1mL concentrated hydrochloric acid, dilute to 100mL with 50% ethanol aqueous solution; starch indicator solution: 5g/L. Weigh 1.0g soluble starch, add 10mL water, inject into 200mL boiling water under stirring, and then boil slightly for 2min, and let stand. Take the upper clear liquid for use;
developing agent: benzene + acetone = 7+3 (V/V);
silica gel G: particle size 10~40μm.
4.1.2.2.3 Apparatus
Chromatography cylinder;
Chromatography plate: 20cm×20cm smooth glass plate; Volumetric flask (calibrated): 25mL;
Iodine volumetric flask: 500mL;
GB15583—1995
Pipette (calibrate the capacity according to the actual operating conditions): 1mL; Pipettor;
Suction filtration and pressure reducing device;
Dryer;| |tt||Absorbent cotton: Wash with ethanol and water, dry and set aside; 4.1.2.2.4 Determination steps
Preparation of chromatography platewwW.bzxz.Net
Weigh about 20g of silica gel G, add about 40mL of water in a mortar, grind into a uniform paste, pour evenly on a pre-cleaned 20cmX20cm glass plate, and gently vibrate to remove bubbles, dry it horizontally, and then put it in a 130℃ oven to dry for half an hour, take it out, and put it in a desiccator for use.
b. Preparation of sample solution
Weigh 1.8~2.0g of sample (accurate to 0.0002g), put it in a 25mL volumetric flask, dissolve it with ethanol and dilute it to the scale, and shake it well.
Thin layer separation
Take an activated chromatography plate, and use a 1mL pipette to place 1mL of the sample solution in a straight line at 2.5cm from the bottom and 1.5cm on both sides. After the solvent evaporates completely, scrape off 5cm wide silica gel on both sides of the chromatography plate, and then stand the plate upright in a chromatography cylinder filled with saturated vapor of the developing agent, and control the depth of the chromatography plate immersed in the solvent to be 0.5-1.0cm. When the developing agent rises to a height of about 15cm, take out the chromatography plate and put it in a fume hood to evaporate the solvent. Use palladium chloride to develop color, mark the outline of the malathion band area, and transfer all of this part of silica gel to the absorber, wipe the glass plate with a small amount of water-moistened absorbent cotton, and put the absorbent cotton into the absorber together, connect the absorber to a 500mL iodine volume bottle, and connect it to the suction filtration and decompression device, elute with 75mL boiling water five times (15mL each time) and filter into a 500mL iodine volume bottle, and rinse the bottle wall with a small amount of distilled water. Accurately add 25mL of 0.15mol/L potassium bromate-potassium bromide solution, add 10mL of 1+4 sulfuric acid, plug the bottle stopper, shake well, and seal with a small amount of water. Place at 28±1℃ for 15min, add 10mL of 30% potassium iodide aqueous solution, shake and place for 2min, titrate with 0.1mol/L sodium thiosulfate standard solution to light yellow, add 3mL of 5g/L starch indicator solution, and continue to drip until the solution fades, which is the end point. Perform a blank test under the same conditions. 4.1.2.2.5 Calculation The mass percentage X of dimethoate in the sample shall be calculated according to formula (2): X = cV,-V,)X 0. 016 38
the volume of sodium thiosulfate standard solution consumed in the blank test, mL; where: V,
V, the volume of sodium thiosulfate standard solution consumed in the sample titration, mL; c—actual concentration of sodium thiosulfate standard titration solution, mol/L; m
.*·(2)
-mass of sample, g;
the mass of dimethoate expressed in grams equivalent to 1.00 mL of sodium thiosulfate standard titration solution (c(NaS,O,)=1.00 mol/L) 0.01638—
6 Allowable difference
4. 1 2. 2. 6
The difference between the results of two parallel determinations shall not exceed 0.6%. Take the average value and report the result. 4.2 Determination of moisture
Determine according to the Karl Fischer method in GB/T1600 (micro-moisture meter with equivalent accuracy is allowed). 4.3 Determination of acidity
4.3.1 Reagents and solutions
GB15583—1995
Sodium hydroxide (GB629) standard titration solution, c(NaOH)=0.02mol/L: Indicator solution: 1g/L bromocresol green ethanol solution mixed with 2g/L methyl red ethanol solution (3+1). 4.3.2 Determination steps
Weigh 1g of sample, accurate to 0.002g, place in a 250mL conical flask, add 30mL of 50% ethanol aqueous solution, shake to dissolve the sample, add 3 drops of indicator solution, and titrate with sodium hydroxide standard titration solution until the color changes from red to bright green. At the same time, make a blank determination.
The acidity X of the sample expressed as mass percentage is calculated according to formula (3): X, cV,-Ve) × 0. 049 × 100m
Where: c-
The actual concentration of sodium hydroxide standard titration solution, mol/L; V,——the volume of sodium hydroxide standard titration solution consumed in titrating the sample solution, mL, V. —Volume of sodium hydroxide standard titration solution consumed in titrating blank solution, mL; 9
-mass of sample, g;
.....(3)
Mass of sulfuric acid in grams equivalent to 1.00mL sodium hydroxide standard titration solution (c(NaOH)=1.000mol/L).
4.4 Emulsion stability test
Performed in accordance with GB/T1603. No floating oil on the top, no sinking oil or precipitation below is qualified. 4.5 Low temperature stability test
Put 50mL of sample in a 100mL beaker, cool to 0±1℃ by appropriate method, and keep at this temperature for 1h. During this period, stir slowly with a glass rod from time to time. No solid or oily matter is precipitated, which is qualified. 4.6 Thermal storage stability test
4.6.1 Apparatus
Thermostatic box (or thermostatic water bath), 54±2℃; 50mL of annular bottle (or glass bottle with a stopper that can still be sealed at 54℃); 50mL of medical syringe.
4.6.2 Determination steps
Use a syringe to inject about 30mL of the emulsifiable concentrate sample into a clean annular bottle (or glass bottle) (avoid the sample from contacting the bottleneck), place the annular bottle in an ice-salt bath for cooling, and quickly seal it with a high-temperature flame (avoid solvent volatilization). Seal at least two bottles and weigh them separately. Place the sealed annular bottle in a metal container, and then place the metal container in a thermostatic box (or water bath) at 54±2℃ for 14 days. Take out and weigh them separately. For samples whose weight has not changed, test the specified items within 24 hours. 4.6.3 Allowable relative decomposition rate
After hot storage, the allowable decomposition rate of 40% dimethoate EC is ≤10%; the hot storage relative decomposition rate of dimethoate EC (%(X,)) is calculated according to formula (4): X, - Xs
5×100
wherein; X,——the dimethoate content measured on the sample before hot storage, %; X——the dimethoate content measured on the same sample after hot storage, %. The samples before and after hot storage should be measured at the same time. 5 Inspection rules
5.1 Sampling method
(4)
The sampling method shall be carried out in accordance with the "sampling of emulsions and liquids" method in GB/T1605. The sampling packages shall be determined by random method, and the final sampling volume shall generally be not less than 250mL.
5.2 Acceptance rules
The acceptance shall be carried out in accordance with GB/T1604 standard.
6 Marking, packaging, transportation and storage
GB15583-1995
6.1 The packaging and marking of Dimethoate EC shall comply with the relevant provisions of GB3796 and GB4838. 6.2 Dimethoate EC shall be packaged in brown glass bottles with stoppers and caps, and the net weight of each bottle shall be 0.5kg or 1kg, with anti-vibration net, foam plastic, straw or corrugated paper as cushion, tightly arranged in calcium plastic box, carton or wooden box to prevent damage from impact, no more than 20 bottles per box, 6.3 According to user requirements or agreement reached between supply and demand, other forms of packaging can be used, but they must comply with the relevant requirements of GB4838.
6.4 During transportation and storage, moisture and sunlight should be strictly prevented and good ventilation should be maintained. It should not be mixed with food, seeds, and feed. Avoid contact with the skin and prevent inhalation through the mouth and nose.
6.5 Packages should be stored in ventilated and dry warehouses, and the stacking method should comply with the principles of safety and convenient handling. 6.6 Safety: Dimethoate is an organophosphorus insecticide that inhibits cholinesterase. It is toxic if swallowed or inhaled. It can be absorbed through the skin and contact with the skin should be avoided. When handling this product, wear protective gloves and gas masks and wear clean protective clothing. After use, rinse with soap and water.
This product should be kept out of reach of children and away from food, animal feed and its containers. If poisoning occurs, consult a doctor. Atropine and antidote are effective antidotes. If necessary, artificial respiration should be performed. 6.7 Warranty period: Under the specified storage and transportation conditions, the warranty period of Dimethoate EC is two years from the date of production. During the warranty period, the effective content shall not be less than 39.0% within half a year; not less than 38.0% within one year; not less than 36.0% within two years. During the warranty period, the acidity shall not be greater than 0.7%.
Additional remarks:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard was drafted by Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Jiang Minyi, Li Xiujie, Mei Baogui, Wang Xuecheng, Hou Yukai, Qiu Chengguo and Liu Chunchun. From the date of implementation of this standard, the former Ministry of Chemical Industry standard HG2-1212-79 "Dimethoate Emulsifiable Concentrate" will be invalid.
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