Some standard content:
National Standard of the People's Republic of China
Methy! bromide technical
Other names, structural formulas and basic physicochemical parameters of methyl bromide are as follows: ISO common name: Methylbromide
CIPAC digital code: 128
Chemical name: Monobromomethane
Structural formula: H
Empirical formula: CH, Br
Relative molecular mass: 94.94 (according to the international relative atomic mass in 1989) Biological properties: It has insecticidal and bactericidal effects and is used as a fumigant. Melting point: -94℃
Boiling point: 3.5℃
Vapor pressure (20C): 0.189MPa
GB 434-1995
Replaces GB 434--82
Solubility (g/L, 20℃): Easily soluble in low molecular alcohols, ethers, esters, ketones; organic solvents such as halogenated alkanes, aromatic alkanes and carbon disulfide. The solubility in water is 17.5.
Stability: Chemically stable and not easily decomposed by acidic and alkaline substances. Storage is stable at room temperature. Content and scope of application
This standard specifies the technical requirements, test methods, inspection rules, and marking, packaging, transportation and storage requirements of methyl bromide technical. This standard applies to methyl bromide technical composed of methyl bromide and impurities generated in its production, and there should be no added modifiers. 2 Reference standards
Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents GB/T 601
Preparation of preparations and products used in test methods for chemical reagents GB/T 603
GB/T 1604
Acceptance rules for pesticides
GB/T 1605
Method for sampling of commercial pesticides
GB2890 Filter-type gas masks
GB3796 General rules for pesticide packaging
3 Technical requirements
3.1 Appearance: It is a colorless gas at room temperature and pressure. It is a colorless or light yellow transparent liquid under pressure or freezing. 3.2 Methyl bromide 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, 1996
Methyl bromide content
Acidity (in terms of HBr)
Non-volatile matter content
4 Test method
GB 434—1995
Superior quality
Unless otherwise specified, all reagents used in this test are analytically pure. 4.1 Identification test of methyl bromide
—Superior quality
%(m/m)
Gas chromatography—This identification test can be carried out simultaneously with the determination of methyl bromide content. The retention time of the main chromatographic peak of the sample solution and the retention time of methyl bromide of the standard solution under the same conditions should have a deviation within 1.0%. Infrared spectroscopy—There should be no obvious difference between the infrared spectra of the sample and the standard. 4.2 Determination of methyl bromide content
4.2.1 Gas chromatography internal standard method (arbitration method) 4.2.1.1 Method summary
The sample is dissolved in dichloromethane, chloroform is used as the internal standard, and a stainless steel column filled with 10% polyethylene glycol 20M/silanized 101 white carrier and a thermal conductivity cell detector are used to separate and determine methyl bromide by gas chromatography. 4.2.1.2 Reagents and solutions
Acetone (GB/T686);
Dichloromethane (GB/T 678);
Methyl bromide standard; known content, ≥99.5% (m/m); internal standard: chloroform, which should not contain impurities that interfere with the analysis; stationary phase: polyethylene glycol 20M;
Carrier: silanized 101 white carrier, 180~250 nylon (60~80 mesh). 4.2.1.3 Instruments
Gas chromatograph: with thermal conductivity cell detector; chromatographic data processor;
Chromatographic column: 2m×4mm (id) stainless steel column; column filling: polyethylene glycol fixed liquid coated on 101 carrier, fixed liquid: carrier = 10:100 (m/m). 4.2.1.4 Preparation of chromatographic column
Coating of fixed liquid
Weigh 2.0g polyethylene glycol 20M, put it in a beaker, add an appropriate amount of acetone to make it a homogeneous solution, add a certain amount of carrier (about 20g) according to the ratio of the fixed liquid, so that it is immersed in the fixed liquid solution, and gently shake the beaker to avoid the carrier from breaking. Place it in a fume hood and evaporate the solvent to near dryness at room temperature, and dry it in an oven at 110℃ for 2h. b. Filling of chromatographic column
Connect a small funnel to the outlet of the chromatographic column (after washing and drying), 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 mouth. Move the funnel to the inlet 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 filled evenly and tightly. After filling, plug a small ball of glass wool at the inlet end and press it appropriately to keep the column filler from moving. c.
Aging of chromatographic column
GB 434—1995
Connect the inlet end of the chromatographic column to the vaporization chamber, do not connect the outlet end to the detector first, pass the carrier gas at a flow rate of 10mL/min, heat it to 130℃ in stages, and age it at this temperature for at least 24h. After cooling, connect the column outlet to the detector. 4.2.1.5 Gas chromatography operating conditions
Column temperature: 70℃
Vaporization chamber temperature: 100℃
Detector temperature: 100℃
Carrier gas (ammonia or hydrogen) flow rate: about 30mL/min; bridge current: about 120mA;
Retention time: methyl bromide about 1.3min; dichloromethane about 4.4min, chloroform about 7.9min. 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.
4.2.1.6 Operation steps
a. Preparation of standard solution: Place 10mL of dichloromethane in a 25mL volumetric flask and weigh accurately (accurate to 0.0002g); first add 4mL of chloroform to the volumetric flask and weigh accurately (accurate to 0.0002g); then take out 5mL of bromomethyl standard sample from the ice bath and add it to the volumetric flask and weigh accurately (accurate to 0.0002g); finally dilute to the scale with difluoromethane and mix carefully. Cover tightly and place in an ice bath.
Preparation of sample solution: Same as a.
Determination: Under the above operating conditions, after the instrument baseline is stable, continuously inject several needles of standard solution and calculate the relative response value of each needle c.
Repeatability: When the relative response value of two adjacent needles changes less than 1.0%, inject and analyze in the order of standard solution, sample solution, sample solution, and standard solution.
4.2.1.7 Calculate the relative correction factor f (round to four significant figures) of methyl bromide according to formula (1): × ms ×P
the average value of the peak area of the internal standard in the two injections of standard solution; where: Ainternal →
Astandard—the average value of the peak area of methyl bromide in the two injections of standard solution; the sample weight of the internal standard in the standard solution, g; minternal
mstandard—the sample weight of methyl bromide standard sample, g; P—the purity of methyl bromide standard sample, m/m.
The mass percentage content (X) of methyl bromide in the sample is calculated according to formula (2): A#×m'±×f×100
A'meat×msample
Wherein: A'meat—the average value of the peak area of the internal standard in two injections of sample solution; Asample
the average value of the peak area of methyl bromide in one or two injections of sample solution; m'meat—
the sample weight of the internal standard in the sample solution, g; the sample weight of the sample, g;
relative correction factor of methyl bromide.
·（2）
4.2.1.8 Allowable difference
GB 434 --- 1995
Figure 1 Gas chromatogram of methyl bromide technical (internal standard method) 1-methyl ether; 2-chloromethane 3-bromomethane;
4-Solvent 5-Trifluoromethane
The difference between the parallel determination results of this method should not exceed 1.0% (m/m); take the average value as the reported result.
4.2.2 Gas chromatography area normalization method
4.2.2.1 Method summary
Use a stainless steel column filled with 10% polyethylene glycol 20M/silanized 101 carrier and a thermal conductivity cell detector to chromatographically separate and determine methyl bromide. Calculate the percentage of methyl bromide by area normalization method. 4.2.2.2 Reagents and solutions
Acetone (GB/T686);
Fixed liquid: polyethylene glycol 20M;
Carrier: silanized 101 white carrier, 180～250um (60～80 mesh). 4.2.2.3 Apparatus is the same as 5.2.1.3.
4.2.2.4 Preparation of chromatographic column is the same as 5.2.1.4. 4.2.2.5 Gas chromatography operating conditions are the same as 5.2.1.5. 4.2.2.6 Operating steps
Inject the methyl bromide sample into a clean and dry glass volume, quickly put it into an ice bath, then put the microinjector into the methyl bromide and freeze it together for about 5 minutes, quickly inject about 1μL, and obtain the chromatogram (see Figure 2). 480
4.2.2.7 Calculation
GB 434--1995
Figure 2 Gas chromatogram of methyl bromide technical (area normalization method) 1-methyl ether; 2-chloromethane 3-bromomethane
The mass percentage of methyl bromide in the sample (X3) is calculated according to formula (3): A
A +A, + 0.5A, × (100 - X,)X
Wherein: Al-
Peak area of methyl bromide;
A2—Peak area of methyl chloride;
Peak area of methyl ether;
0.5—Correction factor of methyl ether;
X. —Mass percentage of non-volatile matter measured in 5.4. 4.2.2.8 Allowable difference
The difference between the results of two parallel determinations shall not exceed 0.5% (m/m); take the average value and report it as the result.
4.3 Determination of acidity
4.3.1 Reagents and solutions
Sodium hydroxide (GB629): standard titration solution, c(NaOH) = 0.01 mol/L, prepared according to GB/T601, and then diluted. Methyl red (HG/T3-958): 1g/L ethanol solution, prepared according to GB/T603. 4.3.2 Determination steps
(3))
In a fume hood, quickly measure 15.0mL of the sample and place it in a 250mL conical flask containing 50mL of distilled water. Place the conical flask in a 3050℃ water bath and shake the conical flask from time to time to evaporate the methyl bromide until the solution becomes transparent. Then, add 3 drops of methyl red indicator solution to the solution and titrate with 0.01 mol/L sodium hydroxide standard titration solution until the solution changes from red to yellow. At the same time, perform a blank determination. The acidity of the sample expressed in mass percentage (X4) is calculated according to formula (4): 481
GB434---1995
x - (Vx 0. 080 9 × 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; V-volume of the sample, mL;
1.73---density of the sample, g/cm~;bZxz.net
·(4))
0.0809--mass of hydrobromic acid (HBr) in grams equivalent to 1.00mL of sodium hydroxide standard titration solution Lc(NaOH)=1.000mol/LJ.
4.4 Determination of non-volatile content
Quickly measure 20.0mL of sample and place it in a conical flask of known mass (accurate to 0.0002g), place it on a water bath, maintain 30~50℃, evaporate to dryness in a fume hood, remove the conical flask from the water bath, wipe the outer wall of the flask with filter paper, and then place it in an oven pre-adjusted and constant at 110±2℃ for 1h, take it out, put it in a desiccator to cool to room temperature and weigh it (accurate to 0.0002g). The mass percentage of non-volatile matter in the sample (X,) is calculated according to formula (5): ml=m2 × 100
Where: m1—mass of non-volatile matter and conical flask, g; m2——mass of conical flask, g:
V-volume of sample, mL;
1.73--—density of sample, g/cm2.
5 Inspection rules
. (5)
5.1 Sampling method According to GB/T1605, samples are randomly taken from any cylinder of each batch of products. The final sampling volume should be no less than 100mL.
5.2 Acceptance rules
Acceptance should be carried out in accordance with GB/T1604.
6 Marking, packaging, transportation and storage
The packaging and marking of methyl bromide technical shall comply with the relevant provisions of GB3796 and be trademarked. 6.1
6.2 Methyl bromide technical shall be packaged in clean, dry, special cylinders with copper valves and shall not leak. Before filling, the cylinders shall be inspected by the factory inspection department in accordance with the gas cylinder safety supervision regulations issued by the Ministry of Labor. Only after passing the inspection can they be filled. 6.3 The filling volume of methyl bromide cylinders shall not exceed 1.57kg/L. The main packaging specifications are 40kg and 100kg. 6.4 During storage and transportation, strictly prevent moisture, exposure to sunlight and violent impact, and prevent rough loading and unloading. 6.5 Methyl bromide cylinders should be stored in ventilated and dry indoor warehouses. 6.6 Safety: Methyl bromide is a highly toxic chemical. It is toxic if swallowed or inhaled. It can penetrate through the skin. When using this product, you should wear loose protective clothing and gloves that are not made of rubber. If necessary, wear a filter-type gas mask that meets the relevant requirements of GB2890. If methyl bromide liquid splashes on the skin or eyes, it should be quickly rinsed with plenty of water. If herpes appears on the skin, it can be repeatedly scrubbed with glucose solution. If poisoning symptoms such as dizziness, nausea, staggering walking, and mental sluggishness occur, medical treatment should be carried out quickly. There is no specific antidote for this product. Drinking more sugar water and milk is beneficial to operators and poisoned people. 482
GB434—1995
Warranty period: Under the specified storage conditions, the warranty period of methyl bromide technical is two years from the date of production. During the warranty period, the technical grade of 6.7-bromomethane should still meet the standard requirements.
Additional Notes:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical supervision of Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is drafted by Lianyungang Seawater Chemical Plant No. 1. The main drafters of this standard are Su Changliu, Hou Yukai and Zhang Gengzhu. 483080 9 × 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; V--volume of the sample, mL;
1.73--density of the sample, g/cm~;
·（4）)
0.0809--mass of hydrobromic acid (HBr) in grams equivalent to 1.00mL sodium hydroxide standard titration solution Lc(NaOH)=1.000mol/LJ.
4.4 Determination of non-volatile content
Quickly measure 20.0mL of sample and place it in a conical flask of known mass (accurate to 0.0002g), place it on a water bath, maintain 30~50℃, evaporate to dryness in a fume hood, remove the conical flask from the water bath, wipe the outer wall of the flask with filter paper, and then place it in an oven pre-adjusted and constant at 110±2℃ for 1h, take it out, put it in a desiccator to cool to room temperature and weigh it (accurate to 0.0002g). The mass percentage of non-volatile matter in the sample (X,) is calculated according to formula (5): ml=m2 × 100
Where: m1—mass of non-volatile matter and conical flask, g; m2——mass of conical flask, g:
V-volume of sample, mL;
1.73--—density of sample, g/cm2.
5 Inspection rules
. (5)
5.1 Sampling method According to GB/T1605, samples are randomly taken from any cylinder of each batch of products. The final sampling volume should be no less than 100mL.
5.2 Acceptance rules
Acceptance should be carried out in accordance with GB/T1604.
6 Marking, packaging, transportation and storage
The packaging and marking of methyl bromide technical shall comply with the relevant provisions of GB3796 and be trademarked. 6.1
6.2 Methyl bromide technical shall be packaged in clean, dry, special cylinders with copper valves and shall not leak. Before filling, the cylinders shall be inspected by the factory inspection department in accordance with the gas cylinder safety supervision regulations issued by the Ministry of Labor. Only after passing the inspection can they be filled. 6.3 The filling volume of methyl bromide cylinders shall not exceed 1.57kg/L. The main packaging specifications are 40kg and 100kg. 6.4 During storage and transportation, strictly prevent moisture, exposure to sunlight and violent impact, and prevent rough loading and unloading. 6.5 Methyl bromide cylinders should be stored in ventilated and dry indoor warehouses. 6.6 Safety: Methyl bromide is a highly toxic chemical. It is toxic if swallowed or inhaled. It can penetrate through the skin. When using this product, you should wear loose protective clothing and gloves that are not made of rubber. If necessary, wear a filter-type gas mask that meets the relevant requirements of GB2890. If methyl bromide liquid splashes on the skin or eyes, it should be quickly rinsed with plenty of water. If herpes appears on the skin, it can be repeatedly scrubbed with glucose solution. If poisoning symptoms such as dizziness, nausea, staggering walking, and mental sluggishness occur, medical treatment should be carried out quickly. There is no specific antidote for this product. Drinking more sugar water and milk is beneficial to operators and poisoned people. 482
GB434—1995
Warranty period: Under the specified storage conditions, the warranty period of methyl bromide technical is two years from the date of production. During the warranty period, the technical grade of 6.7-bromomethane should still meet the standard requirements.
Additional Notes:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical supervision of Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is drafted by Lianyungang Seawater Chemical Plant No. 1. The main drafters of this standard are Su Changliu, Hou Yukai and Zhang Gengzhu. 483080 9 × 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; V--volume of the sample, mL;
1.73--density of the sample, g/cm~;
·（4）)
0.0809--mass of hydrobromic acid (HBr) in grams equivalent to 1.00mL sodium hydroxide standard titration solution Lc(NaOH)=1.000mol/LJ.
4.4 Determination of non-volatile content
Quickly measure 20.0mL of sample and place it in a conical flask of known mass (accurate to 0.0002g), place it on a water bath, maintain 30~50℃, evaporate to dryness in a fume hood, remove the conical flask from the water bath, wipe the outer wall of the flask with filter paper, and then place it in an oven pre-adjusted and constant at 110±2℃ for 1h, take it out, put it in a desiccator to cool to room temperature and weigh it (accurate to 0.0002g). The mass percentage of non-volatile matter in the sample (X,) is calculated according to formula (5): ml=m2 × 100
Where: m1—mass of non-volatile matter and conical flask, g; m2——mass of conical flask, g:
V-volume of sample, mL;
1.73--—density of sample, g/cm2.
5 Inspection rules
. (5)
5.1 Sampling method According to GB/T1605, samples are randomly taken from any cylinder of each batch of products. The final sampling volume should be no less than 100mL.
5.2 Acceptance rules
Acceptance should be carried out in accordance with GB/T1604.
6 Marking, packaging, transportation and storage
The packaging and marking of methyl bromide technical shall comply with the relevant provisions of GB3796 and be trademarked. 6.1
6.2 Methyl bromide technical shall be packaged in clean, dry, special cylinders with copper valves and shall not leak. Before filling, the cylinders shall be inspected by the factory inspection department in accordance with the gas cylinder safety supervision regulations issued by the Ministry of Labor. Only after passing the inspection can they be filled. 6.3 The filling volume of methyl bromide cylinders shall not exceed 1.57kg/L. The main packaging specifications are 40kg and 100kg. 6.4 During storage and transportation, strictly prevent moisture, exposure to sunlight and violent impact, and prevent rough loading and unloading. 6.5 Methyl bromide cylinders should be stored in ventilated and dry indoor warehouses. 6.6 Safety: Methyl bromide is a highly toxic chemical. It is toxic if swallowed or inhaled. It can penetrate through the skin. When using this product, you should wear loose protective clothing and gloves that are not made of rubber. If necessary, wear a filter-type gas mask that meets the relevant requirements of GB2890. If methyl bromide liquid splashes on the skin or eyes, it should be quickly rinsed with plenty of water. If herpes appears on the skin, it can be repeatedly scrubbed with glucose solution. If poisoning symptoms such as dizziness, nausea, staggering walking, and mental sluggishness occur, medical treatment should be carried out quickly. There is no specific antidote for this product. Drinking more sugar water and milk is beneficial to operators and poisoned people. 482
GB434—1995
Warranty period: Under the specified storage conditions, the warranty period of methyl bromide technical is two years from the date of production. During the warranty period, the technical grade of 6.7-bromomethane should still meet the standard requirements.
Additional Notes:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical supervision of Shenyang Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard is drafted by Lianyungang Seawater Chemical Plant No. 1. The main drafters of this standard are Su Changliu, Hou Yukai and Zhang Gengzhu. 483
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.