Some standard content:
National Standard of the People's Republic of China
Dimethoate technical
Other names, structural formulas and basic physicochemical parameters of dimethoate are as follows: ISO common name: dimethoate
CIPAC digital code: 59
Chemical name: O,O-dimethyl S-(N-methylcarbamoylmethyl) dithiophosphate Structural formula:
(CH,O),P-
--S---CH2CO--NHCH3
Empirical formula: C,H12NO,PS2
Relative molecular mass: 229.26 (according to the 1989 international relative atomic mass) Biological properties: pesticide
Melting point: 51~52℃
Vapor pressure (30℃) 5.9995Pa
GB 15582—1995
Solubility: 25g/L in water, 21℃, easily soluble in benzene, toluene, ethanol, ether, acetone, chloroform, dichloromethane and ester organic solvents. Slightly soluble in xylene, carbon tetrachloride, n-hexane, n-heptane and aliphatic hydrocarbons, and difficult to dissolve in petroleum ether. Stability: quite stable in acidic solution. Easily hydrolyzed in alkaline medium. Stable to sunlight, moisture can cause decomposition, and heating can convert into SCH: isomers.
1 Subject content and scope of application
This standard specifies the technical requirements, test methods, inspection rules, and requirements for marking, packaging, transportation and storage of dimethoate technical. This standard applies to dimethoate technical composed of dimethoate and impurities generated in its production, which should be free of foreign impurities. 2 Reference standards
GB/T601 Preparation of standard solution for titration analysis (volume analysis) of chemical reagents GB/T1600 Determination of moisture content in pesticides
GB/T1604
Acceptance rules for pesticides
Sampling methods for commercial pesticides
GB/T 1605F
GB3796 General rules for pesticide packaging
3 Technical conditions
3.1 Appearance: This product is a yellow to brown solid or viscous liquid. 3.2 Dimethoate technical shall also meet the following index requirements: Approved by the State Administration of Technical Supervision on June 12, 1995, and implemented on February 1, 1996Www.bzxZ.net
Dimethoate content
Acetone insoluble matter\
Acidity (in H2SO,)
Note 1) This index shall be inspected at least once a quarter. 4 Test methods
GB15582--1995
Superior products
First-class products
%(m/m)
Qualified products
Unless otherwise specified, the reagents used in this test are analytically pure, and the water used should meet the third-grade water specifications in GB6682. 4.1 Determination of dimethoate technical
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 should be used for identification. Gas chromatography: This identification test can be carried out simultaneously with the determination of dimethoate content. 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 spectra of the sample and the standard. Tinoh
4.1.2 Determination of dimethoate content
4.1.2.1 Gas chromatography
4.1.2.1.1 Summary of method
Figure 1 Infrared spectrum of dimethoate standard sample
400cm-
GB15582—1995
The sample was dissolved in acetone, and n-tricosane (or di-n-pentyl terephthalate) was used as the internal standard. The dimethoate technical was separated and determined by gas chromatography using a glass column filled with 3% OV-17/Chromosorb W-HP and a hydrogen flame ionization detector. 4.1.2.1.2 Reagents and solutions
Solvent: acetone (GB/T686);
Dimethoate standard: known content, ≥99.0% (m/m); Internal standard: n-tricosane (or di-n-pentyl terephthalate), which should not contain impurities that interfere with analysis; Stationary liquid: 0V-17
Carrier: Chromosorb W-HPDMCS, 180～250 μm. Internal standard solution: weigh 0.56g of n-tricosane (or 0.8g of di-n-pentyl terephthalate) and place it in a 100mL volumetric flask, add acetone to dissolve, 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: 1 m×2 mm (id) glass column; Column filling: OV-17 coated on Chromosorb W-HPDMCS (180-250 μm), stationary liquid: carrier = 3:100 (m/m); Chromatographic processor;
Glass wool: silanized.
4.1.2.1.4 Preparation of chromatographic column
a. Coating of stationary liquid
Accurately weigh 0.060 g of OV-17 stationary liquid into a 250 mL beaker, add an appropriate amount (slightly larger than the volume of the carrier) of chloroform to completely dissolve it, pour in 2.0 g of the carrier, shake gently to mix evenly and evaporate the solvent to near dryness. Then place the beaker in an oven at 110°C for 1 hour, take it out and place it in a desiccator to cool to room temperature before loading it into the column. b. Filling of the chromatographic column
Connect a funnel to the outlet of the washed and dried chromatographic column, and fill the prepared filler into the column in batches, while constantly tapping the column wall until it is filled to 1.5 cm from the column outlet. Move the funnel to the inlet of the chromatographic column, plug a small ball of silanized glass wool at the outlet end, connect it to the vacuum pump through a rubber tube, turn on the vacuum pump, continue to slowly add the filler, and constantly tap the column wall to make the filler fill the chromatographic column evenly and tightly. After filling, also plug a small ball of glass wool at the inlet end and press it appropriately to prevent the column filler from moving. c. Aging of the chromatographic column
Connect the inlet end of the chromatographic column to the vaporization chamber, do not connect the outlet end to the detector first, and introduce carrier gas (N,) 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 the chromatographic column
After the aging of the chromatographic column is completed, reduce the column temperature to about 140℃, and use a 50μL syringe to inject 5% (or 10%) dimethyldichlorosilane toluene solution (or other silanization reagent) into the vaporization chamber, 20μL each time, 30min interval, for a total of 8 times, and finally stay for at least 2h. After passivation is completed, connect the column outlet end 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) 30 mL/min, hydrogen, about 30 mL/min, air, about 300 mL/min; retention time: dimethoate, about 3.6 min; n-tricosane, about 9.7 min (di-n-pentyl terephthalate, about 8.7 min). 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.
GB 15582-1995
Figure 2 Gas chromatogram of dimethoate technical drug (with tricosane) 1 - Solvent (acetone); 2 - Dimethoate; 3 - Internal standard (n-tricosane) 4.1.2.1.6 Determination steps
a. Preparation of standard solution
Figure 3 Gas chromatogram of dimethoate technical drug (with di-n-pentyl terephthalate)
1 Solvent (acetone); 2 - Dimethoate; 3 - Internal standard (di-n-pentyl terephthalate) Weigh about 0.1 g (accurate to 0.0002 g) of dimethoate standard sample and place it in a stoppered glass bottle. Use a pipette to accurately transfer 5 mL of the internal standard solution and shake well.
b. 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.
c. Determination
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, = r2m,P
GB 15582—1995
Wherein: r—standard sample solution,The average value of the peak area ratio of dimethoate to the internal standard; r2-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, g;
P-the percentage 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 1.2%. 4.1.2.2 Thin layer-bromination method (arbitration method) 4.1.2.2.1 Method summary
The sample is subjected to thin layer chromatography to separate dimethoate from impurities, and the band containing dimethoate is scraped off and then determined by bromination method. 4.1.2.2.2 Reagents and solutions
Anhydrous ethanol (GB/T678);
Acetone (GB/T686);
Sulfuric acid (GB/T 625);
Benzene (GB/T 690);
Potassium bromate (GB/T650);
Potassium bromide (GB/T649);
Potassium iodide (GB/T1272): 30% aqueous solution; Sulfuric acid 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; Potassium bromate-potassium bromide solution: c(1/6KBrO,)=0.15mol/L. Weigh 4.2g potassium bromate and 40g potassium bromide, dissolve in 1000mL water, shake the hook;
sodium thiosulfate (GB/T637) standard titration solution: c(Na2S2O.) = 0.1mol/L; palladium chloride indicator solution: 1g/L. Weigh 0.1g palladium 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 2 min, 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;
Pipette (calibrate the capacity according to actual operating conditions): 1mL; Pipettor;
Suction filtration and pressure reducing device;
Dryer;
Absorbent cotton: wash with ethanol and water, dry and set aside. 4.1.2.2.4 Determination steps
a. Preparation of chromatography plate
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
GB15582—1995
Weigh 0.75g 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. c. Thin layer separation
Take an activated chromatography plate, and use a 1mL pipette to place 1mL of sample solution in a straight line at 2.5cm from the bottom and 1.5cm on both sides. After the solvent evaporates, scrape off 5mm wide silica gel on both sides of the chromatography plate, and then stand the plate upright in a layer-breaking 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 the color, mark the outline of the dimethoate band area, and transfer all this 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 a 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°C for 15 minutes, add 10 mL of 30% potassium iodide aqueous solution, shake for 2 minutes, titrate with 0.1 mol/L sodium thiosulfate standard solution until it turns light yellow, add 3 mL of 5 g/L starch indicator solution, and continue to titrate until the solution fades. Perform a blank test under the same conditions. 4.1.2.2.5 Calculate the mass percentage X of dimethoate in the sample according to formula (2): Xx = V/-Vx0.016 38 × 100
The volume of sodium thiosulfate standard solution consumed in the blank test, mL; Where: V—-1
V,-the volume of sodium thiosulfate standard solution consumed in the sample titration, mL; c-the actual concentration of the sodium thiosulfate standard titration solution, mol/L; m-—the mass of the sample, g;
0.01638——the mass of dimethoate expressed in grams equivalent to 1.00mL of sodium thiosulfate standard titration solution Cc(NazS,0,)=1.00mol/L).
4.1.2.2.6 Allowable difference
The difference between the results of two parallel determinations shall not exceed 1.0%. Take the average value and report it as the result. 4.2 Determination of moisture
The determination shall be carried out according to the Karl Fischer method (when the moisture content is less than or equal to 1.0%) or the azeotropic distillation method (when the moisture content is greater than or equal to 1.0) in GB/T1600 standard (it is allowed to use a micro-moisture meter with equivalent accuracy). 4.3 Determination of acidity
4.3.1 Reagents and solutions
Sodium hydroxide (GB/T629) standard titration solution, c (NaOH) 0.02mol/L; indicator solution: 1g/L bromocresol green ethanol solution and 2g/L methyl red ethanol solution mixed (3+1). 4.3.2 Determination steps
Weigh 1g of sample to an accuracy of 0.002g, place it 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 as the end point. At the same time, perform a blank determination.
The acidity X of the sample expressed as a percentage by mass is calculated according to formula (3): X, = VV) × 0. 049 × 100
Wherein: c-actual concentration of sodium hydroxide standard titration solution, mol/L; V-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 the blank solution, mL; m-mass of the sample, g,
0.049——-mass of sulfuric acid expressed in grams equivalent to 1.00mL sodium hydroxide standard titration solution Lc(NaOH)=1.000mol/LJ.
4.4 Determination of acetone insoluble matter
4.4.1 Reagents
GB 15582-1995
Acetone (GB/T686): dried over anhydrous sodium sulfate. 4.4.2 Apparatus
Erlenmeyer flask: with ground glass joint, 250mL reflux condenser: matched with flask;
Goowell or glass sand core crucible: 3
Oven: 110±2℃
4.4.3 Determination steps
Weigh 10g sample, accurate to 0.01g, put it into an Erlenmeyer flask, add 50mL acetone, heat and reflux until all soluble substances are dissolved. Filter the solution with a constant weight crucible, then wash the Erlenmeyer flask with 60mL acetone three times, and filter. Place the crucible in an oven at 110℃ to dry for 30 min, take it out and cool it to room temperature, and weigh it. The mass percentage X of the solid insoluble matter in acetone is calculated according to formula (4): X = m = m × 100
The mass of the insoluble matter after constant weight, g;
Where: m
mo—the mass of the crucible, g;
m—the mass of the sample, g.
5 Inspection rules
5.1 Sampling method
(4)
Sampling shall be carried out in accordance with the "raw powder sampling" and "emulsion and liquid state sampling" methods in GB/T1605. The sampling package shall be determined by random method, and the final sampling volume shall not be less than 250g. 5.2 Acceptance rules
Acceptance shall be carried out in accordance with GB/T1604 standard.
6 Marking, packaging, transportation and storage
6.1 The packaging and marking of dimethoate technical shall comply with the relevant provisions of GB3796 and shall be marked with a trademark. 6.2 Dimethoate technical should be packaged in large-mouth plastic barrels, or in other forms of packaging according to the agreement reached between the supplier and the buyer, but it must comply with the relevant requirements of GB3796.
6.3 During transportation and storage, it should be strictly prevented from moisture and sunlight, and good ventilation should be maintained. It should not be mixed with food, seeds, and feed. Avoid contact with skin and prevent inhalation through the mouth and nose.
6.4 The packages should be stored in a ventilated and dry warehouse. 6.5 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 using the medicine, rinse with soap and water.
This product should be kept out of the reach of children and away from food, animal feed and its containers. If poisoning occurs, consult a doctor. Atropine and phosphate are effective antidotes. If necessary, artificial respiration should be performed. 6.6 Warranty period: Under the specified storage and transportation conditions, the warranty period of Dimethoate technical is one year from the date of production. During the warranty period, the effective content is allowed to drop by 2.5% in half a year and by 5% in one year. During the warranty period, the acidity should not exceed 1.0%. 641
Additional notes:
GB15582-1995
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of the Shenyang Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by the Shenyang Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Jiang Minyi, Li Xiujie, Mei Baogui, Wang Xuecheng, Hou Zikai, Qiu Chengguo and Liu Chunchun. From the date of implementation of this standard, the former Ministry of Chemical Industry standard HG2-1417-81 "Dimethoate Crude Oil" shall be invalid. 642
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