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Chemical Industry Standard of the People's Republic of China
HG2312-92
Ethephon Aqueous Agent
Published on June 1, 1992
Ministry of Chemical Industry of the People's Republic of China
Implemented on January 1, 1993
Chemical Industry Standard of the People's Republic of China
Ethephon Aqueous Agent
Subject Content and Scope of Application
HG2312-92
This standard specifies the technical requirements, test methods, inspection rules, and marking, packaging, transportation and storage requirements for ethephon aqueous agent. This standard applies to phosphites synthesized from ethylene oxide and phosphorus trichloride, and the aqueous agent obtained by diluting the original ethephon drug after molecular rearrangement at high temperature and acid hydrolysis. Active ingredient: Ethephon
Chemical name: 2-chloroethylphosphonic acid
Structural formula:
CICH2CH2
Molecular formula: C2HCIOP
Relative molecular mass: 144.45 (according to the international relative atomic mass in 1989)2
Cited standards
GB1601
GB1604
GB1605
GB3796
GB5451
3Technical requirements
Method for determination of hydrogen ion concentration of pesticides
Pesticide acceptance rules
Sampling method for commercial pesticides
General rules for pesticide packaging
Method for determination of wettability of pesticide wettable powder Appearance: colorless to light brown liquid.
3.2 Ethephon water-based agent shall meet the following requirements: Item
Ethephon content, % (m/m)
Dilution stability
Hot storage stability\
Low temperature stability 2)
Note: 1) and 2) shall be inspected at least once every six months. Item
Approved by the Ministry of Chemical Industry of the People's Republic of China on June 1, 1992
Implementation on January 1, 1993
4 Test method
4.1 Determination of ethephon content
4.1.1 Summary of method
HG2312—92
Weigh the sample, esterify it with diazomethane, separate and determine the ethephon methyl ester by gas chromatography using p-nitrochlorobenzene as internal standard solution, 10% SE-30/GasChromQ chromatographic column and hydrogen flame ionization detector. 4.1.2 Reagents and solutions
Saturated solution of diazomethane ether: see Appendix A for preparation; acetone (GB686): analytical grade;
Ethephon standard: known content;
p-Nitrochlorobenzene: internal standard;
Carrier: CasChromQ150180um (80~100 mesh); Stationary phase: SE-30
Chloroform (GB682): analytical grade.
4.1.3 Preparation of internal standard solution
Weigh 5g of p-nitrochlorobenzene and add it to a 100mL volumetric flask, dilute to the mark with acetone, and prepare a 50mg/mL internal standard solution. 4.1.4 Instruments
Gas chromatograph: with FID detector;
Chromatographic column: 2000mm×3mm (inner diameter) glass or stainless steel column, filled with 10% SE-30/GasChromQ150~180um (80～100 mesh).
4.1.5 Operation steps
4.1.5.1 Preparation of chromatographic column
a. Coating of stationary liquid
Weigh 1.00g SE-30 in a 100mL round-bottom flask, add 40mL chloroform to dissolve. Heat and reflux on a water bath for 2h to completely dissolve SE-30, slowly add 10g dry GasChromQ (150～180um) through a clean glass funnel to soak the carrier in the solution. After leaving at room temperature, transfer all the SE-30 solution and the carrier to the evaporator. Slowly drive off the solvent under the infrared lamp in the fume hood, and turn the carrier three times with a steel spoon to make it evenly coated. Then move it to a 90-100℃ oven and bake for 30 minutes. b. Filling of the chromatographic column
Connect a small funnel to the inlet of the cleaned and dried chromatographic column, fill the outlet with an appropriate amount of glass wool and wrap it with gauze, connect it to the vacuum pump through a rubber tube, then turn on the vacuum pump and slowly pour the filler from the funnel, and keep tapping the column wall to make the filler fill the chromatographic column evenly and tightly. Remove the chromatographic column, plug the glass wool at the inlet, and press it appropriately to keep the filler from moving. Aging of the chromatographic column
Connect the inlet of the chromatographic column to the vaporization chamber of the gas chromatograph, and do not connect the outlet to the detector. Raise the nitrogen flow rate of about 10mL/min in stages to 240℃, and age at this temperature for 10h. After cooling, connect the outlet of the column to the detector. 4.1.5.2 Gas chromatography operating conditionsWww.bzxZ.net
Temperature:
Column chamber 160℃;
Vaporization chamber 190℃;
Detector temperature 200℃,
Gas flow rate:
Carrier gas (N2) 14mL/min;
Hydrogen (H2) 35mL/min;
Air: 580mL/min;
Injection volume:
Retention time:
Peak 1 ethephon methyl ester about 4.4min;
Peak 2 internal standard about 6.4min.
Chromatogram (see Figure 1)
HG2312-92
Figure 1 Chromatogram after ethephon methylation
Analysis operating conditions can be appropriately adjusted according to different types of instruments to obtain the best results. 4.1.5.3 Preparation of standard sample solution
Weigh about 0.06g (accurate to 0.0001g) of standard sample containing ethephon and add it to a 50mL conical flask with a ground mouth. Add diazomethane ether solution in an ice bath until it turns yellow. Put the stopper on and shake it in an ice bath for 30 minutes until the yellow color does not disappear. Use nitrogen to blow away the ether and diazomethane in a 30℃ water bath, accurately add 2mL of internal standard solution and shake well. 4.1.5.4 Preparation of test sample
Same as in 4.1.5.3.
4.1.5.5 Determination
Inject several injections of standard sample solution according to the gas chromatography conditions in 4.1.5.2 until the peak area ratio of two adjacent injections does not change by more than 1.5%, and then inject in the following order.
a. Standard solution;
b. Sample solution;
c Sample solution;
d. Standard solution.
Use a 10uL micro syringe to inject 1uL each time with two injections of sample and two injections of standard, so that the peak area ratio does not change more than 1.5%, otherwise repeat the injection.
4.1.5.6 Calculation
Average the obtained peak area ratios of a, d and b, c respectively, and calculate the mass percentage content of ethephon r1 according to formula (1): r2·mi.w
Ti·m2
Wherein: -
the average value of the peak area ratios of ethephon methyl ester and internal standard in the standard solution; (1)
HG2312—92
t2——the average value of the peak area ratios of ethephon methyl ester and internal standard in the sample solution; m1—the mass of the ethephon standard, g;
m2——the mass of the ethephon sample, g; w
——the mass percentage content of the ethephon standard, %4.1.5.7 Allowable difference
The difference between the results of two parallel determinations should be less than 1.5%. 4.2 Determination of pH
4.2.1 Determine by pH meter method in GB1601 Method for determination of hydrogen ion concentration of pesticide. 4.3 Dilution stability
4.3.1 Reagents and instruments
Standard water: Prepared according to the method in GB5451; 100mL measuring cylinder.
4.3.2 Determination steps
Dilute 5mL of preparation with 95mL of standard water to 100mL, place the solution at 20℃ for 1h, and it is qualified if no precipitation occurs. 4.4 Thermal storage stability
4.4.1 Instruments
Thermostatic box: temperature control accuracy is ±2℃; ampoule: capacity is about 20mL, long neck.
4.4.2 Take 5g of the sample and put it into a clean ampoule, seal it with fire, weigh it, and store it in a constant temperature box at 54±2℃ for 14 days. Take it out and cool it to room temperature, weigh it, and take the sample in the ampoule with no change in mass before and after storage for post-storage analysis. The decomposition rate 2 is calculated according to formula (2): ms-ml×100.…
Where: ms—the content of ethephon before hot storage, g; m—the content of ethephon after hot storage, g.
The decomposition rate after hot storage is less than 3% to be qualified. 4.5 Low temperature stability
（2）
Take 100mL of the sample in a 200mL beaker, place it in an ice water bath for 1h, shake it every 15min, and it is qualified if there is no crystallization, no precipitation, and no stratification.
5 Acceptance rules
5.1 Acceptance rules shall be in accordance with GB1604.
5.2 Sampling methods shall be in accordance with GB1605.
6 Marking, packaging, transportation, purchase and storage
6.1 The packaging markings of ethephon water-based agent shall comply with the relevant provisions of GB3796. The packaging shall have the trademark, standard number, production license (or production permit) number and pesticide registration number.
6.2 During storage and transportation, it should be handled with care.
6.3 This product shall not come into contact with alkaline substances, and cannot be mixed with other pesticides and fertilizers for stacking and use: it must be strictly protected from sunlight and rain, and maintained with good ventilation; it shall not be mixed with food, seeds, and feed, avoid contact with the skin, prevent inhalation through the mouth and nose, and shall comply with the provisions of GB190 Dangerous Goods Transport Regulations.
6.4 The shelf life is two years.
A12-Preparation of nitroso-2-methylurea
HG2312—92
Appendix A
Preparation of diazomethane
(Supplement)
In a weighed 250mL flask, add 13.5g of methylamine hydrochloride, then add 67g of water, then add 40.2g of urea, reflux slowly for 2h45min, then reflux vigorously for 15min, cool to room temperature, add 20.2g of sodium nitrite, and cool the entire solution to 0℃. Add 80g of ice to a 1L beaker and cool in an ice-salt bath, then add 13.3g of concentrated sulfuric acid, and add the freshly prepared methyl urea-nitrite while stirring so that the temperature does not exceed 0℃. The addition takes about 1h.
Nitrosomethylurea forms a crystalline foamy precipitate floating on the surface, which is immediately filtered by suction and pressed dry, then washed with a small amount of ice water. The resulting crystals are dried in a vacuum dryer at a temperature not exceeding 4°C. 2 Preparation of diazomethane
Put 60mL of 50% potassium hydroxide aqueous solution and 200mL of ether in a 500mL round-bottom flask, cool the mixture to 0°C, then add 20.62-nitroso-2-methylurea while shaking, and install a condenser on the flask for distillation. The lower end of the condenser is connected to a receiving tube, which is immersed in the 40mL ether liquid in a 250mL conical flask through a double-hole rubber stopper. The conical flask is placed in an ice-salt bath for cooling. The released gas is passed into the second 40mL ether that is also cooled to below 0℃. The reaction flask is placed in a 50℃ water bath to reach the boiling point of ether. It is shaken from time to time. The ether is evaporated until the distillate becomes colorless. Usually, the distillate becomes colorless after 2/3 of the acetaldehyde is evaporated. In any case, the ether cannot be evaporated to dryness. The ether solution in the receiver is combined, which contains 5.3-5.9g of diazomethane.
Additional remarks:
This standard is 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 Element Institute of Nankai University, and Shanghai Pengpu Chemical Plant and Jiangsu Huaiyin Electrochemical Plant participated in the drafting. The main drafters of this standard are Yan Bingwen, Zhu Changshou, Chen Yong, Yang Zuoliang, Li Maoqing, Liang Qinying and Wang Qinsun.
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