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The preparation of pesticides is to prepare commercial pesticides into a state that can be sprayed in the field. For example, wettable powders, suspensions, and emulsifiable concentrates, and the like. The mixing and preparation of pesticides must be done before the pesticides are used. Generally speaking, as long as the properties of the medicaments are mastered, they can be mixed and prepared. However, due to the fact that there are still many pesticide formulations in China that have not yet been standardized, they may not be fully summarized in this table. Therefore, the nature of the agents should be carefully understood before the actual compounding, and even necessary tests are required.
Mixing of alkaline agents Commonly used alkaline agents are stone sulphur mixture, Bordeaux mixture, insecticidal double water agent and rosin mixture. When mixing, pay attention to the correct operation procedure.
Such as stone sulfur mixture is the most commonly used alkaline agent, it allows temporary mixing with trichlorfon, with the use, but pay attention to a few points in preparation:
First, the two drugs must be prepared with the same amount of liquid separately. At this time, the concentration should be increased by one time, so that the concentration in the mixing when the two liquid phases are mixed just meets the initial requirements. Next, the alkaline solution (stone sulphur mixture) should be poured into the trichlorfon aqueous solution while mixing, and the mixture is quickly stirred. Thus, the pH of the mixture is increased more slowly.
Then there is the crystal powder of trichlorfon which tends to agglomerate and is relatively insoluble. It is often necessary to use hot water or warming to promote dissolution. The solution thus obtained is a hot solution. It must be allowed to cool sufficiently before mixing with the stone sulphur solution. Because trichlorfon is significantly accelerated in the case of heat, it is not conducive to uniform mixing.
Mixing of Suspensions Most of the plastic suspensions on the market have a deposition phenomenon, that is, the upper layer gradually becomes thinner and the lower layer becomes thicker during storage. Some of the domestic rubber suspensions are also prone to lower agglomeration, and the general shaking and stick stirring are difficult to spread. Therefore, a two-step formulation must be employed when using such a formulation with a pharmaceutical solution.
In a two-step preparation, the suspension is first dispersed into a uniform diffusion solution and then diluted to the desired concentration.
Mixing of wettable powders Although wettable powders are soluble in water, the rate of dissolution is fast and slow. Therefore, the wettable powder cannot be put into a large amount of water at a time, and it cannot be directly put into the liquid medicine of another prepared pesticide. A two-step preparation method must be adopted, that is, first prepare a small amount of wettable powder solution, and then dilute to the desired concentration; or first prepare a solution of soluble powder, and then mix with the spray liquid of another pesticide. Attention must be paid to the recording of water usage during the preparation process.
This preparation method is not only advantageous for some special dosage forms, but also has a large amount of spraying in the field, and it is necessary to repeatedly take the medicine repeatedly, and the method is also advantageous for accurate medicine taking and reducing the risk of exposure to the original medicine poisoning. For example, a 50% cream formulation of methamidophos is used, which is 50 grams of emulsifiable concentrate per acre and 50 liters of water. If the spray solution is prepared in a barrel, 12.5 liters of water per barrel, a total of 4 barrels. 12.5 grams of methamidophos EC was taken per barrel. Therefore, the amount of emulsifiable concentrate is added to the sprayer for a total of 4 chances of contamination. Moreover, 12.5 grams of emulsifiable concentrate was taken at a time, and the amount was small and the error was large. If you take a two-step preparation, the operation is as follows:
The first step is to prepare a solution of methamidophos. Take 50 grams of emulsifiable concentrate once, add 350 ml of water, and mix well to obtain 400 ml of mother liquor. In actual operation, the measuring device is used to measure the true volume of the mother liquor, because the specific gravity of various emulsifiable concentrates is not equal to 1. If less than 1, the mother liquor volume will be greater than 400 ml; if greater than 1, it will be less than 400 ml. In addition, some of the drugs may shrink in volume after being dissolved in water, and some may not shrink. The second step is to prepare a spray solution in the sprayer. 12.4 liters of water can be added to each barrel and 100 ml of the above mother liquor can be added. The 100 ml mother liquor is easier to measure accurately, and the concentration is much smaller than that of the emulsifiable concentrate, and the fluidity is also good, and the risk of contamination on the outside of the vessel is rather small. The greater the amount of field work, the more obvious the benefits of this approach.
Mixing of powders Mixing of powders, if there is no special equipment, is more difficult to mix evenly than liquid preparations. If the user needs to carry out a large amount of powder mixing, it is best to use a special mixing machine, such as a special powder machine, a seed dresser, etc., the device can be sealed, the dust is not easy to fly, not only safe, but also the mixing effect is good. If you mix it with cockroaches on the open field, it is difficult to mix evenly, and the dust is flying, which is very dangerous.
When using the powder mixing method, it is impossible to absolutely no dust flying, so it is necessary to wear protective equipment such as goggles and masks.
Pesticide should be paid attention to when preparing, the pesticide and ingredients should be taken accurately, and the mixing and preparation should be uniform. Master these basic principles and be able to handle pesticides.
Author: Liu Guoxin
Source of information: China Cooperation Times
Mixing of alkaline agents Commonly used alkaline agents are stone sulphur mixture, Bordeaux mixture, insecticidal double water agent and rosin mixture. When mixing, pay attention to the correct operation procedure.
Such as stone sulfur mixture is the most commonly used alkaline agent, it allows temporary mixing with trichlorfon, with the use, but pay attention to a few points in preparation:
First, the two drugs must be prepared with the same amount of liquid separately. At this time, the concentration should be increased by one time, so that the concentration in the mixing when the two liquid phases are mixed just meets the initial requirements. Next, the alkaline solution (stone sulphur mixture) should be poured into the trichlorfon aqueous solution while mixing, and the mixture is quickly stirred. Thus, the pH of the mixture is increased more slowly.
Then there is the crystal powder of trichlorfon which tends to agglomerate and is relatively insoluble. It is often necessary to use hot water or warming to promote dissolution. The solution thus obtained is a hot solution. It must be allowed to cool sufficiently before mixing with the stone sulphur solution. Because trichlorfon is significantly accelerated in the case of heat, it is not conducive to uniform mixing.
Mixing of Suspensions Most of the plastic suspensions on the market have a deposition phenomenon, that is, the upper layer gradually becomes thinner and the lower layer becomes thicker during storage. Some of the domestic rubber suspensions are also prone to lower agglomeration, and the general shaking and stick stirring are difficult to spread. Therefore, a two-step formulation must be employed when using such a formulation with a pharmaceutical solution.
In a two-step preparation, the suspension is first dispersed into a uniform diffusion solution and then diluted to the desired concentration.
Mixing of wettable powders Although wettable powders are soluble in water, the rate of dissolution is fast and slow. Therefore, the wettable powder cannot be put into a large amount of water at a time, and it cannot be directly put into the liquid medicine of another prepared pesticide. A two-step preparation method must be adopted, that is, first prepare a small amount of wettable powder solution, and then dilute to the desired concentration; or first prepare a solution of soluble powder, and then mix with the spray liquid of another pesticide. Attention must be paid to the recording of water usage during the preparation process.
This preparation method is not only advantageous for some special dosage forms, but also has a large amount of spraying in the field, and it is necessary to repeatedly take the medicine repeatedly, and the method is also advantageous for accurate medicine taking and reducing the risk of exposure to the original medicine poisoning. For example, a 50% cream formulation of methamidophos is used, which is 50 grams of emulsifiable concentrate per acre and 50 liters of water. If the spray solution is prepared in a barrel, 12.5 liters of water per barrel, a total of 4 barrels. 12.5 grams of methamidophos EC was taken per barrel. Therefore, the amount of emulsifiable concentrate is added to the sprayer for a total of 4 chances of contamination. Moreover, 12.5 grams of emulsifiable concentrate was taken at a time, and the amount was small and the error was large. If you take a two-step preparation, the operation is as follows:
The first step is to prepare a solution of methamidophos. Take 50 grams of emulsifiable concentrate once, add 350 ml of water, and mix well to obtain 400 ml of mother liquor. In actual operation, the measuring device is used to measure the true volume of the mother liquor, because the specific gravity of various emulsifiable concentrates is not equal to 1. If less than 1, the mother liquor volume will be greater than 400 ml; if greater than 1, it will be less than 400 ml. In addition, some of the drugs may shrink in volume after being dissolved in water, and some may not shrink. The second step is to prepare a spray solution in the sprayer. 12.4 liters of water can be added to each barrel and 100 ml of the above mother liquor can be added. The 100 ml mother liquor is easier to measure accurately, and the concentration is much smaller than that of the emulsifiable concentrate, and the fluidity is also good, and the risk of contamination on the outside of the vessel is rather small. The greater the amount of field work, the more obvious the benefits of this approach.
Mixing of powders Mixing of powders, if there is no special equipment, is more difficult to mix evenly than liquid preparations. If the user needs to carry out a large amount of powder mixing, it is best to use a special mixing machine, such as a special powder machine, a seed dresser, etc., the device can be sealed, the dust is not easy to fly, not only safe, but also the mixing effect is good. If you mix it with cockroaches on the open field, it is difficult to mix evenly, and the dust is flying, which is very dangerous.
When using the powder mixing method, it is impossible to absolutely no dust flying, so it is necessary to wear protective equipment such as goggles and masks.
Pesticide should be paid attention to when preparing, the pesticide and ingredients should be taken accurately, and the mixing and preparation should be uniform. Master these basic principles and be able to handle pesticides.
Author: Liu Guoxin
Source of information: China Cooperation Times
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