Dilution method
The percentage concentration refers to the number of medicines and fertilizers in 100 parts of the fertilizer or medicine powder, which is expressed by “%â€.
For example: 2% urea means 2 kg of urea and 98 kg of water in 100 kg of urea solution.
2. Multiple concentration
Refers to the water addition multiple of 1 pesticide , which is usually expressed by weight.
For example, a 700-fold 50% carbendazim is prepared by mixing 1 part of 50% carbendazim with 700 parts of water.
3. Conversion method
The conversion formula for converting percentage concentration to ppm concentration is:
The amount of water added to a pesticide = the percentage of pesticide × 1000000 / the number of ppm to be formulated.
For example, the content of 40% ethylene is 1 kg of a 2000 ppm solution, and the amount of ethylene added is 40% x 1000000/2000 = 200 parts.
4. Convert to multiple concentration
Divide the percentage by the number of ppm and shift the decimal point back by 4 to get the dilution factor.
For example: 40% ethephon 1000ppm, when converted to a multiple concentration, use 40÷1000=0.04, the decimal point is shifted back 4 places, that is, 400 times.
5. Watering method
When several pesticides are mixed, it is not necessary to add water once for each additional drug, but to use various drugs: the same concentration of water is used to calculate the concentration.
For example, 500 times of urea and 1000 times of methyl thiophanate are prepared by adding 2 parts of urea plus 1 part of methyl thiophanate plus 1000 parts of water. In addition, when watering, it should be formulated into mother liquor first, that is, first use a small amount of warm water to open the liquid, then add water to the desired concentration, fully dissolve, to improve the efficacy and prevent phytotoxicity.
How to properly dilute pesticides?
First, the method of expressing the concentration of the drug
1. Percent concentration: refers to the number of parts of 100 pesticides, which are often expressed in (%).
2. Million parts concentration: refers to the number of parts of the active ingredient in 1 million pesticides, the symbol is PPm (or micrograms / ml; mg / liter; g / cubic meter, etc.).
3. Multiple method (ie dilution factor): refers to the multiple of water or other thinner (fine soil, particles, etc.) when the commercial pesticide is diluted. Diluted 100 times or 100 times or less, to 1 parts by deducting the original drug agent occupied by the calculation, such as: 50-fold dilution of the original drug i.e. with 1 added portionwise 49 parts of diluent. Diluted more than 100 times, the calculation does not deduct the number of parts of the original drug, such as: diluted 600 times, that is, 1 part of the original drug plus 600 parts of diluent.
Second, the conversion between the concentration representation
1. Conversion between percent concentration and parts per million: ppm concentration (ppm) = 10000 x percent concentration.
2. Conversion between the multiple method and the percent concentration: percent concentration (%) = (original drug concentration / dilution factor) x 100.
Third, the calculation method when diluting pesticides
1. Calculated by active ingredient
(1) Find the amount of diluent (water or filler, etc.):
1 diluted 100 times or less: thinner dosage = original drug weight x (original drug concentration - concentration of the drug) / concentration of the drug.
2 diluted more than 100 times: thinner dosage = original drug weight x original drug concentration / concentration of the drug.
(2) Seeking dose:
The dosage of the original agent = the weight of the drug to be dispensed x the concentration of the drug to be dispensed / the concentration of the original drug.
2. Calculated by the multiple method (regardless of the active ingredient content)
(1) Dilution 100 times or less: diluent dosage = original drug weight × dilution factor - original drug weight.
(2) Dilution more than 100 times: thinner dosage = original drug weight × dilution factor.
(3) The amount of the drug to be used: the amount of the original drug = the weight of the drug to be dispensed / the dilution factor
(4) Find the dilution factor:
1 The dilution ratio is determined by the concentration ratio: dilution factor = original drug concentration / concentration of the drug to be dispensed.
2 by the weight ratio dilution factor: dilution factor = the weight of the drug / original drug weight.
3. Conversion by concentration and concentration unit:
Solution concentration: The solution concentration can be divided into three categories: mass concentration (such as mass percent concentration) and volume concentration (such as molar concentration, equivalent concentration) and mass-volume concentration.
(1) Percentage by mass
The concentration of the solution is expressed as a percentage by mass of the mass of the solute as a percentage of the mass of the whole solution, and is expressed by the symbol %. For example, 25% glucose injection refers to 25 grams of glucose in 100 injectables.
Percentage by mass (%) = solute mass / solution mass 100%
(2) Volume concentration
1 molar concentration: The concentration of the solution is expressed by the molar number of the solute contained in 1 liter of the solution, and is expressed by the symbol mol. For example, 1 liter of concentrated sulfuric acid contains 18.4 moles of sulfuric acid, and the concentration is 18.4 mol. Molar concentration (mol) = number of moles of solute / volume of solution (liter).
2 equivalent concentration (N): The concentration of the solution is expressed by the number of gram equivalents of the solute contained in 1 liter of the solution, and is represented by the symbol N. For example, 1 liter of concentrated hydrochloric acid contains 12.0 grams of equivalent hydrochloric acid (HCl) at a concentration of 12.0N. Equivalent concentration = gram equivalents of solute / solution volume (liters).
(3) mass-volume concentration
The concentration expressed by the mass of the solute contained in the solution per unit volume (1 cubic meter or 1 liter) is called the mass-volume concentration and is expressed by the symbol g/m3 or mg/L. For example, in a 1 liter chromium-containing wastewater containing hexavalent chromium having a mass of 2 mg, the hexavalent chromium concentration is 2 mg/L (mg/L).
Mass-volume concentration = mass of solute (gram or milligram) / volume of solution (m3 or liter).
4. Conversion formula for concentration units
1) Equivalent concentration = 1000.d mass percent concentration / E
2) Mass percent concentration = equivalent concentration E/1000.d
3) molar concentration = 1000.d mass percent concentration / M
4) Mass percent concentration = mass-volume concentration (mg/L) / 104.d
5) mass-volume concentration (mg/L) = 104 mass percent concentration
5. ppm is the percentage of weight
Ppm=mg/kg=mg/L
That is 1ppm=1ppm=1000ug/L
1ppb=1ug/L=0.001mg
Where: E - gram equivalent of solute; d - specific gravity of solution; M - molar mass of solute.
Fourth, PPM concentration exchange algorithm
PPM is a commonly used concentration unit in the world, because PPM is an English abbreviation, not the name of the calculation unit, that is, 1PPM=1x10^-6, that is, 1PPM is one millionth of a concentration.
1G, 100% concentration of the drug diluted 1000KG water is 1PPM concentration, if the active ingredient of the drug concentration is 50%, then 1G, 50% concentration of the drug diluted 500KG water is 1PPM concentration.
For example: How many times does it take to dilute water for 500PPM GA3 (100% content)?
100/500X10000=2000 times
That is, 1G diluted 2000G water is 500PPM concentration; can be substituted by conversion formula: pesticide active ingredient content (%) / chemical liquid effective concentration (PPM) X10000 = water dilution factor.
More pesticide knowledge , please pay attention to China Pesticide Network
(Source: Voice of the Chinese Village)
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