The low-temperature stability of EC is generally that after storage at low temperature (0℃) for 14 days, the appearance of EC should still be a transparent and uniform true solution, and there should be no insolubles.
Stability of emulsion, that is, emulsified oil can still form a stable and uniform emulsion after being diluted with water, with no floating oil and paste at the top and no precipitation at the bottom.
If necessary, the storage stability of EC at room temperature (2 years) should also be checked.
(2) The concentrated emulsion is an oil-in-water concentrated emulsion with water as the medium, which is made of water-insoluble oily pesticide crude oil or high-concentration oil solution of crude drug, emulsifier, dispersant, stabilizer, thickener and water through high-speed shearing homogenization process. The oil droplets are 0.2 ~ 2 microns in diameter and opaque in appearance. When in use, it can be sprayed by mixing water into emulsion, and can also be directly used as ultra-low volume spray, especially for aircraft.
When processing concentrated emulsion, no organic solvent is used at all or only a small amount of solvent is used, which only makes some pesticide raw materials with poor oiliness into a state of good fluidity and easy emulsification. Therefore, compared with emulsifiable concentrate, it requires more stringent stability, which requires not only qualified storage at low temperature and no freezing, but also no breaking of emulsion at room temperature. After adding water to prepare spray, the emulsion can be kept in a stable state.
Concentrated emulsion is a kind of processed emulsion dosage form with little or no organic solvent, and it is one of the non-solvent dosage forms of liquid pesticide dosage form.
(3) Microemulsion This dosage form consists of liquid pesticide, surfactant, water, stabilizer, etc. It belongs to a thermodynamically stable dispersion system. It is characterized in that water is used as the medium and contains no or little organic solvent, so it is non-flammable and non-explosive, safe in production, operation, storage and transportation, less in environmental pollution and saves a lot of organic solvents; The dispersion of pesticides is extremely high, reaching a fine level. Pesticide particles are generally 0. 1 ~ 0.0 1 micron, and their appearance is similar to transparent or slightly transparent liquid. Good dispersibility in water, strong permeability to target and good adhesion. Microemulsion also belongs to the non-solvent dosage form of liquid pesticide, which is a promising new dosage form and has the trend of gradually replacing traditional emulsifiable concentrate. China has successfully developed 8% and 20% fenvalerate microemulsion, 5% and 10% cypermethrin microemulsion, 4.5% beta-cypermethrin microemulsion and 20% cypermethrin-methomyl mixed microemulsion.
(4) Suspension agent was once called "colloidal suspension" because it is a colloidal suspension formed by solid particles in water with a certain viscosity. But it is a suspension system of solid pesticide particles in water, which has considerable system stability, so it is now called "suspension agent".
Suspending agent is a kind of dosage form that contains no organic solvent at all, and it is a good dosage form for processing solid technical drugs. (5) Seed coating agent As far as pesticide formulation is concerned, seed coating agent is not a new dosage form, but some specific preparations with certain adhesion in suspension, which are specially used for seed coating and cannot be used for other purposes.
Some seed coating agents also have special functions, such as adjusting the shape and size of seeds. Treating small seeds of cruciferous crops with seed coating agent, such as beet, tobacco, tomato, leek, lettuce, rape, etc., changes the appearance of seeds, wraps the seeds into round particles, increases the diameter, improves the fluidity of seeds during sowing, and is beneficial to mechanized sowing.
(6) Suspension emulsion is a dispersion system in which fine powder particles of solid drugs and fine oil droplets of oily drugs are dispersed and suspended in water under the action of surfactants. It can be regarded as a mixture of suspending agent and concentrated emulsion, so it is also called "suspension emulsion". The use method of suspension emulsion is also to add water to prepare spray for spraying.
(7) The dry suspending agent is a powder or granular solid dosage form, which can be dispersed spontaneously when put into human water, and the pesticide is suspended in the water with the particle size of 1 ~ 5 microscreen.
All hydrophobic pesticides with low melting point, low steam pressure, good thermal stability and suitable for spraying can be processed into suspending agents. Especially for pesticides that are difficult to be mechanically crushed and easy to hydrolyze and have low solubility in organic solvents, it is more suitable to choose dry suspension.
(8) Wettable powder, as the name implies, has wettability and is used to prepare spray liquid by adding water for spraying. The "wettability" of this dosage form includes two meanings: first, the powder particles of this powdery drug are easily wetted by water, and the powder quickly wets and disperses in water to form a suspension, which has good dispersibility and suspension stability; Secondly, the suspension prepared by adding water must have good wetting and spreading properties. After the liquid medicine is applied to the body, it can well wet the surface of the body and spread into a liquid film, ensuring good drug effect. Therefore, wettability, suspension rate and fineness of powder particles are important quality and technical indexes of this dosage form.
The minimum suspension rate of wettable powder in China is ≥ 50%, which is consistent with the FAO standard of 50% ~ 90%. The higher the suspension rate, the better. During the spraying process, the drug particles will start to sink, which makes the sprayed liquid concentration different. In our country, spraying is mainly carried out by manual sprayer, and there is no stirring device in the medicine cabinet, so we should pay more attention to the suspension rate.
There is a big difference.
Wettable powder is the second largest pesticide dosage form, and its biggest disadvantage is that it is easy to fly away when preparing spraying liquid, which is harmful to operators and pollutes the environment with residual powder in packaging bags. Therefore, several safe wettable powder formulations have been developed, such as the above suspension, water dispersible granules, effervescent tablets, water-soluble packaging bags and so on.
(9) Water dispersible granules, also known as water dispersible granules, are prepared by re-granulating wettable powder or suspending agent. The key technology of processing is to prevent the powder particles from re-flocculating into coarse powder particles during granulation or storage of finished products. Therefore, an additive called isolating agent should be used in the formula to isolate the powder particles. This dosage form requires low shedding rate and there is no powder in the product. The dosage form has the advantages of good fluidity, convenient use, no dust flying and safety.
(10) effervescent tablets (granules) are similar to water dispersible granules. Wettable powder is processed into larger effervescent agent, and each tablet (granule) has a certain weight. For example, it is processed into quantitative tablets, which are measured according to the tablets when used, and there is no need to weigh them separately.
(1 1) Soluble powder is a powder formulation which is composed of water-soluble solid technical drugs, water-soluble fillers and additives, such as monosultap, trichlorfon, jinggangmycin, carbendazim hydrochloride, acetamiprid and gibberellin. Can be processed into soluble powder. The dosage form is used for preparing spray. It should be noted that some soluble powder products do not contain the necessary wetting agent, and the wetting and spreading performance of the spray prepared by this method on the biological surface is poor, so some wetting agents such as neutral washing powder should be added appropriately to ensure the efficacy.
(12) Water-based agent usually has high solubility in water, and it exists in water.
Pesticides that are stable and do not decompose in water can be processed into aqua. For example, 2- methyl -4- monochlorosodium salt, glyphosate, paraquat, imazethapyr, fomesafen, bentazone, chlormequat chloride, ethephon, jinggangmycin, nongkang 120 and dimehypo are all processed into aqua. The processing water treatment agent does not use organic solvent, and the production cost is low. However, if the physical properties of pesticides are suitable for processing into solid dosage forms, it is more reasonable to process them into soluble powders. In aqueous solution, it is better to add wetting AIDS according to the situation.
(13) powder is used for powder spraying, seed dressing and soil treatment.
Generally speaking, the powder content used for powder spraying is relatively low. Since the production of HCH and DDT stopped, the production of powder for dusting basically stopped, and only a small amount of powder was used as sanitary insecticide. However, as a kind of powder for protective crops, the powder is expanding rapidly, and the varieties of powder are also increasing.
(14) The original purpose of particle development is to eliminate powder drift, but now the purpose of developing particles is various. The shapes of particles are spherical, cylindrical and fragmented (also called block particles). The particle size varies greatly, generally between100 and 2 000 microns. Those smaller than 100 microns are called fine particles, those between100 and 300 microns are called large particles, and some weighing 50 grams are called particle tyrants.
Granular agents must have certain mechanical strength to avoid particle breakage and powder generation during packaging, storage, transportation and use. There have been cases of silkworm poisoning due to poor mechanical strength, when the powder was applied, it polluted the adjacent mulberry fields. Another important technical standard for producing granules by coating method is the shedding rate (that is, the amount of powder dropped), which generally does not exceed 5%.
(15) Smoke agent This is a special dosage form. Different from other dosage forms, it is composed of pesticides, accelerators and oxidants, and flame retardants are added when necessary to prevent fires during production, storage and transportation. Insecticides used to process aerosol must be able to become gaseous at a certain temperature without thermal decomposition or have a low decomposition rate. Different pesticides need different temperatures and heat for gasification, and mixed smoke agents are usually not processed.
(16) The oil agent is an oil solution of pesticides. Oil is insoluble in water, so it cannot be diluted and sprayed with water, and can only be sprayed directly. If necessary, it can be diluted and sprayed with an appropriate amount of organic solvent. According to the purpose, usage and application equipment, oil agents can be divided into five types.
Low concentration of oil is limited to indoor spraying to control sanitary pests.
(17) poison bait or poison bait is a dosage form used to lure the target organism to eat. It is mainly used for processing rodenticides and sanitary insecticides, and also widely used for the prevention and control of pests and mollusks in farmland, which are generally prepared by users themselves.
(18) single dose of two pesticides that can be mixed in dispensing barrels in the field are produced in pesticide plant, and then packaged separately. The barrel mixing ratio is indicated on the label or instruction manual, and users can prepare spray liquid according to the chapter. For example, Yibao barrel mixture (50% acetochlor EC 75% thiophanate-methyl dry suspension) and Abao barrel mixture (38% atrazine suspension and 25% sulfuron) produced by Hebei Xuanhua Pesticide Co., Ltd.