The raw unprocessed pesticide produced in the factory is called the original drug , and the original product is solid at room temperature, which is called the original powder, such as the green mellon raw powder. If it is liquid, it is called crude oil, such as Hedandan and Hecao enemy crude oil. The original drug produced by the factory can not be directly applied, and the original drug should be processed into a preparation according to the physical and chemical properties of the original drug and the requirements of the use technology. The quality of the original drug and the preparation has a close relationship with the effect of the application. First, the quality standard of the original drug 1. Purity Purity is the amount of active ingredient in the original drug, expressed as a percentage. Purity is the main indicator of the quality of the original drug, and the higher the percentage of the active ingredient, the better the quality. The quality standards for pesticides published by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) should be more than 90% pure. In China's pesticide quality standards, the purity of the original drug can generally reach more than 90%. The content of impurities in the original pesticide with low purity is high, and the excessive impurities in the original drug have the following disadvantages: (1) may cause phytotoxicity to crops. In 2000, the use of bensulfuron-methyl in rice fields in Meihekou City, Jilin Province, caused phytotoxicity, resulting in rice seedling death. Bensulfuron-methyl has good safety to rice seedlings and generally does not cause phytotoxicity. According to preliminary research, the cause of the phytotoxicity is that the impurities JP-003 and JP-004 in the bensulfuron-methyl are excessive. (2) More impurities will increase the toxicity of plateau drugs to humans. For example, the pure LD50 of methamidophos is 30mg/kg body weight in rats, while the LD50 of 50% methamidophos emulsifiable concentrate produced by some domestic manufacturers is 13.6mg/kg, indicating that the toxicity is increased. There are five kinds of impurities in the amine-phosphorus crude oil, and the toxicity of these five impurities is higher than that of the pure methamidophos. (3) The impurities in the original drug lose the original accuracy by the chemical analysis method of calculating the content of the active ingredient in an amount of an element or an atomic group in the active ingredient molecule. Since the impurities also contain the same elements or atomic groups as the active ingredients, the results of the measurement are biased and do not reflect the true content of the active ingredients in the original drug and its preparation. (4) The impurities in the original drug also bring difficulty to the processed powder, because the presence of the impurities lowers the freezing point of the original drug and is not easily pulverized. (5) The impurities of the original drug can reduce the stability of the active ingredient, and with the use of the pesticide, the impurities enter the environment and cause pollution. Therefore, it is necessary to increase the purity of the original drug as much as possible and reduce the content of impurities. 2. pH The pH is both a quality indicator for the original drug and a quality indicator for the formulation. The pH refers to the amount of free acid or free base in the original pesticide and its preparation, or its hydrogen ion concentration. The purpose of limiting the pH is mainly to reduce the decomposition of the active ingredients in the pesticides and preparations during storage, to prevent the physical properties of the preparations from changing and to cause phytotoxicity when used. It can also be used as a reference for assessing the corrosivity of pesticides on packaging materials. FAO's quality standards for the original drug and preparations and preparations are expressed in terms of acidity (% of H2SO4) or alkalinity (% of NaOH). The original powder is generally required to be <0.1% to 0.2%. The pH is sometimes expressed in terms of pH. In China, the prescriptions for pesticides are expressed in acidity or alkalinity, and most of the preparations are expressed in terms of PH value. 3. Moisture content Moisture content is both the original drug and the quality index of the formulation. The purpose of limiting the moisture content of the original powder of the pesticide is to reduce the decomposition of the active ingredient and maintain chemical stability. For powders and wettable powders, the moisture content is limited to maintain a good dispersion state of the preparation, and it can be well dispersed on the foliage when sprayed. In the pesticide quality standards promulgated by 1971 after FAO, the pesticides have the moisture content index for the pesticides, emulsifiable concentrates and some soluble powders, while the powders and wettable powders have no moisture content. China's water content requirements for powders are not more than 1.5%. However, due to the different types of fillers used in processing powders, their water absorption properties are different, and some fillers have strong water absorption. Even if the moisture content is high, the dispersion properties of the powders are not affected; some fillers have weak water absorption properties, even if the moisture content is not too high. It also affects the dispersibility of the powder. Therefore, it is unreliable to control the moisture content to ensure the dispersibility of the powder. It is more effective to control the dispersibility of the powder by using the fluidity index of the powder than the method of controlling the moisture content. In China, there is no liquidity index in the quality standard of powder pesticides, and the dispersibility is controlled by limiting the moisture content. Second, the quality standards of the preparation 1. Active ingredient content The active ingredient content is the most important indicator in pesticide formulations and is expressed in mass percent g/kg or g/l. An active ingredient is a specific chemical structural component that is biologically active in a pesticide product . Biological activity refers to the disturbance, destruction and killing effect on the behavior, growth, development and physiological and biochemical mechanisms of pests such as insects, cockroaches, pathogens, rats, weeds, etc. It also includes the regulation of the growth and development of animals and plants. The active ingredient content of the pesticide formulation is allowed to vary within a certain range above and below the indicated content, for example 50 g/kg (± 10%). China's standard requirements are not lower than the indicated content, and in recent years there is also a tendency to allow a change within a certain range above and below the indicated content. 2. Powder fineness One of the quality indicators of powder pesticides (powder, wettable powder, suspension, dry suspension, granule). Expressed as a percentage of a certain sieve. For example, in Japan and the United States, the fineness of the powder is 98% through a 45 micron sieve (325 mesh sieve). At present, only 95% of most powders are required to pass through a 75 micron sieve (200 mesh sieve). The efficacy and fineness of powders are closely related. Within a certain range, the efficacy is inversely proportional to the particle size. The smaller the powder of the contact insecticide , the larger the contact surface per unit weight of the agent and the insect body, and the better the contact effect. In gastric toxicity pesticides, the smaller the drug granules, the easier it is for the pests to swallow. After eating, they are more easily absorbed by the intestines and exert toxic effects. However, the granules are too fine, the active ingredient is volatilized, the efficacy period is shortened, and the spray is severely sprayed, which in turn reduces the efficacy and is unfavorable to the environment. Therefore, when determining the fineness of the powder, the appropriate particle size should be determined according to the characteristics of the original drug, the conditions of the processing equipment, and the level of the application machine. 3. Bulk weight Bulk weight is one of the quality indicators of powder. The bulk density is the mass of the powder per unit volume (g/ml), also known as the specific gravity. According to the degree of tightness of filling, the bulk density is divided into two types: loose bulk density and tight bulk density. The former is the bulk density of the powder when it is naturally filled with containers. The latter is the bulk density when the powder is filled into the container and the powder is filled tightly after the predetermined mechanical vibration. The same powder has a small bulk density, indicating that the powder is fine and the powder has a low water content. Under the condition that the measurement method is consistent, the bulk density of the powder and the wettable powder is related to the bulk density of the filler used, the kind of the auxiliary agent, the kind and concentration of the active ingredient, and the fineness of the powder, and the bulk density of the filler has the greatest influence. The choice of filler capacity is important to consider two factors: (1) the loose bulk density of the solid drug and the filler are similar to avoid the separation of the original drug and the filler during the application process, resulting in unevenness of the agent per unit area; (2) from the application The drug and wind speed consider the bulk density of the filler. When the wind speed is less than 2.5 m / s, the bulk density of the powder is required to be in the range of 0.46 to 0.60 g / ml, and the aircraft dusting is required to be between 0.66 and 0.80 g / ml. The bulk density can be used to monitor the degree of pulverization and water content of the powder, and the size of the package and the storage capacity of the powder processing plant can be calculated according to the bulk density of the powder. 4. Wetting property One of the quality indicators of the wettable powder pesticide preparation, the time when the tested wettable powder is sprinkled from a certain height to the surface of the water to completely wet. The measurement method developed in China is to pass a 5 g sample of a 40 mesh sieve (about 400 μm), and sprinkle with a standard hard water of 30 ° C (342 mg / liter, calcium: magnesium = 80:20) at a distance of 100 mm from the water surface. In the beaker, record the time from the sample sprinkling to complete wetting. Many of the original drugs that are insoluble in water are not wettable by water. To change this property, a certain amount of good wetting agent should be added during processing. The wetting agent can reduce the interfacial tension between the pesticide particles and water, so that the powder can be quickly wetted and dispersed by water. The wettable powder not only requires the preparation itself to have the property of being wetted by water, but also needs to be diluted with water according to the dilution factor specified at the time of use to spray the suspension onto the plant, so that the plant can be well wetted and can be spread. . When the wettable powder suspension with poor wettability is sprayed onto the plant, it does not wet and spread well, and the liquid medicine can easily fall off the blade, which reduces the effect of the drug. Therefore, it is common to add some surfactants when applying the wettable powder, which will improve the efficacy, which may also increase the wettability of the suspension. The wettability of wettable powders in FAO is not more than 1 or 2 minutes, and the regulations in China are generally not more than 5 minutes. The purpose of limiting the wetting time is to allow the water to be wetted quickly by dilution with water prior to application and to disperse into a uniform suspension. 5. Suspension rate One of the quality indicators of pesticide formulations such as wettable powders, suspensions, water-dispersible granules and microcapsules. It is diluted with water to a suspension, and after standing at a specific temperature for a certain period of time, the amount of the active ingredient still in suspension is a percentage of the amount of the active ingredient in the original sample. After the above pesticide preparation is diluted into water into a suspension, it is sprayed with a sprayer, and the particles of the active ingredient of the pesticide are required to remain suspended in the suspension for a long period of time without sinking at the bottom of the sprayer, so that the sprayed medicine is sprayed. The liquid is relatively uniform and the control effect is good; if it sinks to the bottom, the concentration of the liquid sprayed out early will decrease, the amount of the drug on the plant will be less, and the control effect will decrease; and the concentration of the liquid sprayed out late may be too high. It causes phytotoxicity to plants, so the suspension suspension rate is an important factor in whether the efficacy of the preparation can play a role. In China, the suspension rate of pesticide preparation dilutions is between 50% and 70%, and a few products require 80%. 6. Emulsion stability One of the quality indicators of emulsifiable pesticide formulations. It is used to measure the uniformity and stability of the dispersion of pesticide beads in water in the emulsion formed by dilution of the cream with water. The emulsifiable pesticide preparation should be diluted with water to form an emulsion and sprayed. Most of the emulsions used in agriculture are oil-in-water (O/W) type, which requires the liquid beads to be evenly distributed in the water for a long time, and the oil and water are not separated, so that the concentration of the active ingredients in the emulsion is kept uniform and the effect is fully exerted. To avoid phytotoxicity. The strength of the stability is related to the variety and amount of emulsifier used in the preparation of the emulsifiable concentrate. The method for detecting emulsion stability of FAO is as follows: the sample treated by heat storage stability is diluted 20 times with standard hard water. Immediately after shaking, it should be completely emulsified. The volume of the cream separated after half an hour of parking is generally not more than 2ml, the volume of cream and oil floating after 2 hours of parking is generally no more than 4ml. After standing for 24 hours, shake again and the isolate should be re-emulsified. The determination standard of emulsion stability formulated in China is: the emulsion is diluted with a certain ratio of 342 mg/L standard hard water (200, 500, 1000 times), stirred and placed in a 100 ml measuring cylinder, and allowed to stand at 25~30 °C for 1 hour. Observe that there should be no oil slick, oil or precipitate. If the dilution is too high, such as 1000 times, even if the emulsion is not stable enough, a small amount of oil or cream is separated, which is not easy to observe. This observation method is unreasonable. The dilution factor with standard hard water should be uniformly specified as 200 times. 7. Tobacco formation rate One of the quality indicators of pesticide smoke agents. The percentage of the active ingredient of the pesticide in the smoke when the smoke agent is burned is expressed as the percentage of the active ingredient of the pesticide in the smoked agent before combustion. In the process of burning smoke, the active ingredient of the smoke agent is affected by heat, and only the part that volatilizes or sublimates into smoke has a control effect, and the rest is decomposed by heat or remains in the slag. The smoke-forming rate of the active ingredient of the smoker is greater than 80%, and the smoke-forming rate of the active ingredient of the mosquito-repellent incense is greater than 60%. Different pesticides have different rates of smoke at the same temperature or the same pesticide at different temperatures, and the temperature depends on the pesticide formulation. A pesticide formulation with a high rate of smoke should be selected to be processed into a smoke agent. Third, the "guarantee period" of pesticide products The Ministry of Chemical Industry, the Ministry of Agriculture and Forestry, and the National Federation of Supply and Marketing Cooperatives jointly issued the “Pesticide Quality Management Regulations†in 1978, of which Article 12 stipulates that pesticide products “should clearly specify the warranty period for products. The warranty period is generally at least 2 years.†It is because after the production of pesticide preparations, it is sometimes left to the next year. If the indicators in the quality standard of the preparations have obvious changes, the effect of prevention and control will not be guaranteed after application. The warranty period for various pesticide formulations in the world is also more than 2 years. The guarantee period is 2 years, that is, within 2 years after the pesticide product is delivered, all the indicators in the product quality standard should be qualified. Fourth, commercial pesticide sampling In the process of factory inspection of the pesticide production enterprise, distribution department and user's inspection and acceptance inspection, arbitration analysis of quality disputes and supervision and spot inspection by the national authorized institution, sampling is the first and most important work, and the sample is inspected. The result is the basis for determining the quality of the products in this batch. In order to standardize the sampling methods for commercial pesticides, the Food and Agriculture Organization of the United Nations (FAO) has developed standards for sampling methods applicable to pesticides as a common standard sampling method for international commercial transactions. China has also established a national standard for sampling methods for commercial pesticides (GB1605-79). The sampling method is as follows: the variety of pesticides and preparations are various, and the physical state is very different. In addition to the general sampling rules, sampling methods should be considered in the sampling of different states: (1) sampling of solid products. The number of samples depends on the weight or number of pieces of the goods. Each batch of 200 or less may be taken at 5%; more than 200 may be taken at 3%. The number of mined parts is preferably 5~10 pieces. Large packaging containers should be taken from the top, middle and bottom sections. It can be sampled with a spoon or a slotted sampler. Each sample is sampled at not less than 100 grams. The sample taken is repeatedly divided by a quarter method, and finally 100 to 150 grams of sealed storage for inspection. (2) Liquid sample sampling. When sampling, try to mix the product as much as possible, and then use the sampler to take out the required capacity. 3~5 pieces of each batch of products are to be mined, and each sample is sampled at not less than 500 ml. The sample taken is evenly mixed. Finally, no less than 200 ml of sample is taken and sealed for storage. (3) Sampling of special form products. Sampling should be done using appropriate methods, depending on the circumstances. For example, an aerosol can be taken from several bottles in each batch. Samples of pesticides taken from a batch of products can only represent this batch of products. Therefore, all samples must be marked: product name, manufacturer, date of manufacture, batch number, date and location of sampling. When both the supply and demand sides dispute the quality of the pesticide product and require arbitration analysis, or when the pesticide quality supervision agency authorized by the state conducts product quality supervision and spot checks, the sampling shall be carried out jointly by both parties to the dispute or between the sampling and the sampled inspection. Both parties sign and seal the samples in duplicate, one for inspection by the inspection agency and one for re-inspection.
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