For new purchases of pesticides , first of all, pay attention to their production date and shelf life. Drugs that are close to or close to the shelf life should not be purchased as much as possible to reduce the risk of drug failure or partial failure. The following is a brief introduction to the identification method of pesticide failure:
1 intuitive method
For powder pesticides, first look at the appearance of the medicament. If it has been obviously agglomerated by moisture, the taste of the medicine is not strong or has other odors, and it can be smashed into a group by hand, indicating that it has basically failed; for the emulsion pesticide, the medicine bottle is first allowed to stand, if the medicine The liquid is turbid or stratified (ie, oil-water separation), precipitate formation or floc suspension, indicating that the agent may have failed.
2 heating method
Suitable for powder pesticides. Take 5-10 grams of pesticides and heat them on a piece of metal. If a large amount of white smoke is produced, and there is a strong pungent smell, it means that the medicine is good. Otherwise, it means that it has failed.
3 floating method
Suitable for wettable powder pesticides. First take 200 grams of water, then weigh 1 gram of pesticide, gently and evenly spread on the water surface to observe carefully, wet in 1 minute and can sink to the water is the non-failed pesticide, otherwise it is a failed pesticide.
4 suspension method
Suitable for wettable powder pesticides. Take 30-50 grams of pesticides, put them in a glass container, add a small amount of water to make a paste, then add 150-200 grams, stir well with water, and let stand for 10 minutes to observe. The pesticides that have not failed are well soluble. The suspended particles in the medium are fine, the sedimentation rate is slow and the amount of sedimentation is small, and the pesticide is reversed.
5 oscillation method
Suitable for emulsion pesticides. For pesticides with oily water layer, first shake the vial with force and let it stand for 1 hour. If stratification still occurs, the agent has deteriorated.
6 hot melt method
Suitable for emulsion pesticides. Put the pesticide with the precipitate into the warm water (the water temperature should not be too high, preferably 50 Â° C -60 Â° C), after 1 hour, if the sediment slowly dissolves, the agent has not expired, and the precipitate is dissolved. After that, it can continue to be used; if the precipitate is difficult to dissolve or dissolve, it means that it has failed and can no longer be used.
7 dilution method
Suitable for emulsion pesticides. Take 50 grams of pesticide, put it in a glass bottle, add 150 grams of water, and shake it vigorously for 30 minutes. If the liquid is evenly milky white, it will be a failed pesticide, and the more the upper layer of oil, the worse the drug.
If the newly purchased pharmacy has any of the following appearances, it should not be purchased; if the stock agent is close to or has passed the shelf life, but it does not want to be wasted, it can be identified by the following method. Without any of the following symptoms, after the partial experiment Used.
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