Some standard content:
Chemical Industry Standard of the People's Republic of China
HG2168—91
Chlorotoluron Technical
Published on November 18, 1991
Ministry of Chemical Industry of the People's Republic of China
Implemented on May 1, 1992
Chemical Industry Standard of the People's Republic of China
Chlorotoluron Technical
Subject Content and Scope of Application
HG2168—91
This standard specifies the technical requirements, test methods, inspection rules, and marking, packaging, transportation and storage requirements for Chlorotoluron Technical. This standard applies to Chlorotoluron Technical.
Active ingredient: Chlorotoluron.
Chemical name, 3(3-chloro-4-methylphenyl)-1,1-dimethylurea Structural formula:
Molecular formula: C1oH1aCIN20
-NHCN(CH)2
Relative molecular mass: 212.7 (according to the international relative atomic mass in 1987) 2 Reference standards
GB 601 Preparation of standard solution for titration analysis (volumetric analysis) of chemical reagents Method for determination of moisture content in pesticides
GB1600
GB1605
GB3796
Technical requirements
Sampling method for commercial pesticides
General rules for pesticide packaging
3.1 Appearance: light yellow to brown solid.
Chlorotoluron technical material shall meet the technical requirements in the following table: %(m/m）
Chlorotoluron content
Moisture content
Acidity (measured in HSO)
or alkalinity (measured in NaOH)
Approved as superior product by the Ministry of Chemical Industry of the People’s Republic of China on November 18, 1991
Qualified product
Implemented on May 1, 1992
4 Test method
4.1 Determination of chlorotoluron content
4.1.1 High performance liquid chromatography (arbitration method) 4.1.1.1 Summary of method
HG2168—91
The sample was dissolved in methanol and separated by a C18 reversed phase liquid chromatography column and determined by a UV detector. The mobile phase was methanol and water. The chlorotoluron content was determined by the external standard method.
4.1.1.2 Reagents and solutions
Methanol (GB683);
Glacial acetic acid (GB676);
Chlorotoluron standard sample: known content.
4.1.1.3 Apparatus
High performance liquid chromatograph: with adjustable wavelength UV detector; Chromatographic column: BondapaurCis, 250mm long, 4.6mm inner diameter stainless steel column; Data processor or recorder;
Micro syringe: 10uL.
4.1.1.4 Operation conditions
Detection wavelength: 243nm (or 245nm); Detection sensitivity: 0.5AUFS;
Column temperature: room temperature;
Mobile phase: methanol + water + glacial acetic acid = 60 + 40 + 0.1 (V/V); Flow rate: 1mL/min;
Retention time: about 10min for chlorotoluron.
4.1.1.5 Determination steps
4.1.1.5.1 Preparation of standard solution
Weigh about 0.1g (accurate to 0.0001g) of chlorotoluron standard sample, place it in a 100mL volumetric flask, dissolve it with methanol, dilute it to the scale with methanol, and shake it well.
4.1.1.5.2 Preparation of sample solution
Weigh a sample containing about 0.1g (accurate to 0.0001g) of chlorotoluron and place it in a 100mL volumetric flask, dissolve it with methanol, dilute it to the mark with methanol, and shake it well.
4.1.1.5.3 Determination
Under the chromatographic conditions specified in 4.1.1.4, after the instrument is stable, first inject several injections of standard solution until the relative deviation of the peak area or peak height of two consecutive injections is less than 1%, and then perform quantitative analysis. It takes about 30 minutes for all components of the sample solution to flow out. The injection order is as follows: a. Standard solution;
b. Sample solution;
c. Sample solution;
Standard solution.
4.1.1.5.4 Calculation
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Figure 1 High Performance Liquid Chromatogram of Chlorotoluron
1-Standard sample; 2-Industrial product
According to the average value of the peak area (or peak height) of chlorotoluron obtained from two injections of standard solution ad and two injections of sample solution b and c, calculate the mass percentage of chlorotoluron in the sample according to formula (1): a1:214
Wherein; A-average value of the peak area (or peak height) of the sample solution; A2-average value of the peak area (or peak height) of the standard solution; mi
-mass of chlorotoluron sample, 8;
-mass of chlorotoluron standard sample, g;
mass percentage of chlorotoluron standard sample, %. 4.1.1.5.5 Allowable Difference
The difference between the parallel determination results of this method shall not exceed 1.0%. 4.1.2 Thin layer-ultraviolet spectrophotometry
4.1.2.1 Summary of the method
After the sample is separated by thin layer, take the silica gel layer of the chlorotoluron band, elute with solvent, and measure it with an ultraviolet spectrophotometer. 4.1.2.2 Reagents and solutions;
95% ethanol (GB679):
Chloroform (GB682);
Ethyl acetate (HG3-1226);
Developing agent: chloroform + ethyl acetate = 80 + 20 (V/V); silica gel GF254: for chromatography.
4.1.2.3 Instruments
Ultraviolet spectrophotometer: equipped with 1cm quartz colorimetric cell; ultraviolet lamp: wavelength 254nm.
4.1.2.4 Determination
4.1.2.4.1 Preparation of thin layer plate
HG2168—91
Weigh 7.5g silica gel GF254, put it in a glass mortar, add 19mL of distilled water, grind it into a uniform paste, and immediately pour it on a pre-cleaned and dried 10cm×20cm glass plate, and gently vibrate it to make the silica gel evenly distributed on the plate without bubbles. Place it on a horizontal surface to air dry naturally, then move it to an oven, activate it at 120-150℃ for 1h, take it out and put it in a desiccator for use. 4.1.2.4.2 Preparation of standard solution
Weigh about 0.05g (accurate to 0.0001g) of chlorotoluron standard sample, place it in a 50mL volumetric flask, dissolve it with 30mL chloroform, then dilute it to the mark with chloroform, shake well, accurately pipette 10mL of the solution into a 25mL volumetric flask, dilute it to the mark with chloroform, and shake well.
4.1.2.4.3 Preparation of sample solution
Weigh about 0.05g (accurate to 0.0001g) of chlorotoluron sample, place it in a 50mL volumetric flask, dissolve it with 30mL chloroform, then dilute it to the mark with chloroform, shake well, accurately pipette 10mL of the solution into a 25mL volumetric flask, dilute it to the mark with chloroform, and shake well.
4.1.2.4.4 Chromatography
Use a 0.5mL pipette to accurately draw 0.3mL of the above standard solution and sample solution respectively. On the activated chromatography plate, place the standard solution and sample solution in a straight line 2cm from the bottom and 1.5cm from both sides. Let the solvent evaporate. Place the plate in a developing cylinder filled with saturated vapor of the developing agent at room temperature. The plate is immersed in the solvent to a depth of about 1cm. When the development front rises to about 14cm from the dot line, take out the plate, wait for the developing agent to evaporate, and then color it under ultraviolet light. Transfer the band of R-0.4 on the plate completely to a glass funnel (lay two layers of qualitative filter paper in the funnel), and elute it into a 25mL volumetric flask with 20mL of 95% ethanol in multiple times (5-6 times), then dilute to the scale with ethanol and shake well. 4.1.2.4.5 Determination
Use 95% ethanol as reference and determine the absorbance of the standard solution and the sample solution at a wavelength of 250nm. 4.1.2.4.6 Calculation
The mass percentage of chlorotoluron in the sample is calculated according to the formula (2): Ar·mz·w.
Wherein: A1—absorbance of the sample solution; A2—absorbance of the standard solution;
m1—mass of the sample, g;
m2—mass of the chlorotoluron standard, g;
substance—mass percentage of the chlorotoluron standard, %. 4.1.2.4.7 Tolerance
The difference between the parallel determination results of this method should not exceed 1.5%. 4.1.3 Chemical-thin layer method
4.1.3.1 Method Summary
The sample is dissolved in dichloromethane, free amine is extracted with hydrochloric acid, dichloromethane is evaporated, the residue is hydrolyzed with potassium hydroxide 1,2-propylene glycol solution, the released amine is absorbed with boric acid solution, and the total amine content is obtained after titration with standard hydrochloric acid solution. The mass percentage of by-product 1[3-(3-chloro-4-methylphenyl)-1-methylurea) and by-product I[3-(4-methylphenyl)-1,1-dimethylurea} determined by thin layer chromatography is then subtracted to obtain the mass percentage of chlorotoluron.
The reaction equation is as follows:
N(CHs)2
+2KOH=CHs
NH2+NH(CH)2+K2CO
2Reagents and solutions
Boric acid (GB628);
1,2-propylene glycol;
Dichloromethane;
N(CHs)2
HG2168—-91
+2KOH=CHs
+2KOH=CHs
NH2+NHCH+K,CO
NH+NH(CH)2+K,COs
NH(CH3)2+HCI-NH2(CHs)2CI
NH,CH:+HCI-NH:CH:C1
Hydrochloric acid (GB622) solution: c(HCI)=1mol/L. Hydrochloric acid (GB622) standard titration solution; c(HCI)=1.000mol/L; Methyl red-methylene blue mixed indicator solution: weigh 60mg methyl red and 40mg methylene blue, dissolve in 100mL95% ethanol. 4.1.3.3 Apparatus: Electromagnetic stirrer; Rotary evaporator: 250 mL separating funnel with glass stopper and stopcock; Distillation apparatus with ground joint (see Figure 2); Burette: 25 mL acid burette with 0.05 graduation. 5
4.1.3.4 Determination steps
HG2168-91
Figure 2 Diagram of distillation apparatus
1—Heating jacket; 2—500mL round-bottom flask; 3—Reflux tube: 4—Dropping funnel; 5—Buffer cover; 6—Condenser; 7—400mL beaker; 8—Electromagnetic stirrer Weigh a sample containing about 3g of chlorotoluron (accurate to 0.0001g), transfer it to a separatory funnel with 100mL of dichloromethane, shake it to completely dissolve the sample, and add 50mL of hydrochloric acid (c(HC1)=1mol/L). Shake vigorously for 1min, and put the organic layer solution into a second separatory funnel, add 25mL of the above hydrochloric acid, shake for 30s, and then put the organic layer into a 500mL flask. Wash the water layer in the two funnels with a total volume of 200 mL of dichloromethane, put the organic layer solution into the flask, and discard the aqueous solution. Evaporate the dichloromethane to dryness in a rotary evaporator (water bath maximum temperature 40°C). Add 100 mL of 12-propylene glycol, 40 g of potassium hydroxide and some zeolite to the residue, and immediately connect the flask tightly to the distillation apparatus. Apply a thin layer of silicone grease to all joints. Add 150 mL of distilled water, 0.2 g of boric acid and 1.0 mL of mixed indicator to the beaker, and the end of the catheter should be placed below the liquid surface. Warm to dissolve all the potassium hydroxide and chlorotoluron in the flask, then boil for 10 minutes to reflux 1,2-propylene glycol in the condenser, and add water from the separatory funnel to the boiling material in the flask at a rate of 1 drop/s to complete the distillation of the amine. At the same time, titrate the amine with a standard hydrochloric acid titration solution, and continue to titrate until the color of the indicator changes from green to blue and remains unchanged for 2 minutes. At the same time, a blank test is performed under the same conditions. 4.1.3.5 Calculation of the mass percentage of chlorotoluron: Calculate according to formula (3): aa=
wherein Vi-
(Vi-V)c·X0.2127
X100-r
is the volume of the standard hydrochloric acid titration solution consumed by the sample, mL; (3)
HG2168-91
V2 is the volume of the standard hydrochloric acid titration solution consumed by the blank, mL; c is the actual concentration of the standard hydrochloric acid titration solution, mol/L; m is the mass of the sample, g;
0.2127 is the mass of chlorotoluron equivalent to 1.00mL of the standard hydrochloric acid titration solution (Cc(HC1)=1.000mol/L), expressed in grams; z4 is the by-product content, see Article 4.1.4 of this standard, % (m/m). 4.1.3.6 Allowable difference
The difference between two determination results shall not be greater than 1%
4.1.4 Determination of by-products 1 and I
This thin layer chromatography method can determine the content of two possible by-products (I and I), which interfere with the determination of chlorotoluron. 4.1.4.1 Method summary
The sample and the standard sample solution of the by-product are separated by thin layer chromatography. Under ultraviolet light, the spots produced by the sample and the standard sample solution of by-products I and I are compared to determine their mass percentage content. 4.1.4.2 Reagents
Standard sample of byproduct I [3-(3-chloro-4-methylphenyl)-1-methylurea], with known content; Standard sample of byproduct I [3-(4-methylphenyl)-1,1-dimethylurea], with known content; Chloroform (GB682);
Ethyl acetate HG3-1226);
Tetrahydrofuran,
Developing agent: Chloroform + Ethyl acetate = 80 + 20 (V/V); Silica gel HF254: for chromatography.
4.1.4.3 Apparatus
Developing cylinder:
Glass plate: 20cmX20cm;
Pipette: 5mL, 0.05 division; wwW.bzxz.Net
Volumetric flask: 50mL, 10mL,
Ultraviolet lamp: wavelength 254nm.
4.1.4.4 Determination
4.1.4.4.1 Preparation of thin layer plate
Weigh 8g silica gel HF254, place in a glass mortar, add 23mL of distilled water, grind to a uniform paste, immediately pour on a pre-cleaned and dried chromatography glass plate, and gently shake to make the silica gel evenly distributed on the plate without bubbles. Place the plate horizontally to air dry naturally, then move it to an oven, activate it at 140℃ for 2h, take it out and place it in a desiccator for use. 4.1.4.4.2 Preparation of sample solution
Weigh 0.5g (accurate to 0.0001g) of sample into a 10mL volumetric flask, dissolve it with tetrahydrofuran and dilute it to the scale, and shake it well. 4.1.4.4.3 Preparation of by-product standard solution Weigh 50±1mg of by-products 1 and I each into a 50mL volumetric flask, dissolve it with tetrahydrofuran and dilute it to the scale, and shake it well. Use a pipette to draw 1.0, 2.0, 3.0, 4.0 and 5.0 mL of the above solution into five 10 mL volumetric flasks respectively, and dilute to the mark with tetrahydrofuran. The corresponding mass percentages are 0.2%, 0.4%, 0.6%, 0.8% and 1.0% respectively. 4.1.4.4.4 Chromatography
On the same thin layer chromatography plate, 2.5 cm from the bottom and 1.5 cm on both sides, use a 5 uL syringe to draw 5 uL of the by-product standard solution (in order of concentration from low to high) and the sample solution and dot them side by side on the plate in a circular pattern. Allow the solvent to evaporate to dryness, place in a developing cylinder filled with saturated developing agent vapor at room temperature, take out when the developing agent front rises to about 13cm from the sample line (about 70min), and compare the spots produced by the sample solution and the by-product standard solution at R values of about 0.25 (by-product I) and 0.35 (by-product I) on the chromatographic plate under ultraviolet light. When the spots of the by-product in the sample solution and the corresponding by-product standard solution are consistent with each other in a certain mass percentage, the content is the mass percentage of the by-product in the sample. HG2168—91
4.1.4.4.5 When the mass percentage of the by-product in the sample solution exceeds 1%, the sample solution should be quantitatively diluted to within the mass percentage range of the by-product standard solution, and then measured according to 4.1.4.4.4. 4.2 Determination of acidity (alkalinity)
4.2.1 Reagents and solutions
Acetone (GB686)
Sodium hydroxide (GB629) standard titration solution: c(NaOH)=0.02mol/L; hydrochloric acid (GB622) standard titration solution: c(HCI)=0.02mol/L; bromocresol green-methyl red indicator solution; Mix 3 parts of 0.1g/100mL bromocresol green ethanol solution with 1 part of 0.2g/100mL methyl red ethanol solution and shake well.
4.2.2 Determination steps
Weigh 1~1.5g of sample (accurate to 0.001g) in a 250mL conical flask, add 80mL acetone to dissolve it, then add 20mL boiled and cooled to room temperature distilled water and 10 drops of bromocresol green-methyl red indicator solution, and titrate to the end point with sodium hydroxide standard titration solution or hydrochloric acid standard titration solution according to the acidity and alkalinity of the sample. 4.2.3 Calculation
The acidity s of chlorotoluron technical expressed in mass percentage is calculated according to formula (4): 6
V·ciX0.049×100
Wherein: c1—actual concentration of sodium hydroxide standard titration solution, mol/L; V——volume of sodium hydroxide standard titration solution consumed by titration sample, mL; mass of sample, g;
0.049——mass of sulfuric acid equivalent to 1.00mL sodium hydroxide standard titration solution [c(Na0H)=1.000mol/L) expressed in grams.
The basicity 6 of chlorotoluron technical expressed as a mass percentage is calculated according to formula (5): X6
VC2X0.040
Wherein: C2——actual concentration of hydrochloric acid standard titration solution, mol/L; V——volume of hydrochloric acid standard titration solution consumed by the titration sample, mL; ..
——mass of sodium hydroxide expressed in grams equivalent to 1.00mL hydrochloric acid standard titration solution [c(HCl)-1.000mol/L].
4.3 Determination of moisture
Determine according to the azeotropic method in GB1600.
5 Inspection rules
5.1 Chlorotoluron technical shall be inspected by the quality supervision and inspection department of the manufacturer. The manufacturer shall ensure that all chlorotoluron technical shipped out of the factory meets the requirements of this standard. Each batch of chlorotoluron technical shipped out of the factory shall be accompanied by a quality certificate in a certain format. 5.2 The user has the right to inspect the quality of the received chlorotoluron technical in accordance with the provisions of this standard to check whether it meets the requirements of this standard.
5.3 Sampling method: According to the technical sampling method in GB1605, the samples are mixed and evenly packed into two clean and dry glass bottles with 8
HG2168-91
ground stoppers. Labels are attached to the bottles, indicating the manufacturer's name, product name, batch number, and sampling date. One bottle is sent to the quality supervision and inspection department for inspection, and the other bottle is sealed.
5.4 If some indicators in the inspection results do not meet the requirements of this standard, samples should be taken from twice the amount of packaging for re-inspection. If only one indicator does not meet the requirements of this standard, the entire batch of chlorotoluron technical is unqualified. 5.5 When the supply and demand parties have disputes over quality, they can be resolved through negotiation between the two parties, or the statutory inspection agency can conduct arbitration analysis according to the inspection method specified in this standard.
6 Marking, packaging, transportation and purchase and storage
6.1 The marking and packaging of chlorotoluron technical shall comply with the relevant provisions of GB3796. 6.2 Chlorotoluron technical shall be packaged in woven bags lined with plastic bags, with the net weight of each bag not exceeding 50kg (other forms of packaging may also be used according to user requirements).
6.3 During storage and transportation, it shall be strictly protected from moisture and sunlight, and maintained with good ventilation; it shall not be mixed with food, seeds and feed, and shall avoid contact with the skin and inhalation through the mouth and nose.
Additional remarks:
This standard was proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of the Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry and the Pesticide Testing Institute of the Ministry of Agriculture. The main drafters of this standard are Jia Lijun, Ma Yaguang, Zhang Baizhen, Wang Yiyan, Zeng Kui and Sun Qili. 9
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