An insecticidal composition of Chlorpyriphos in the form of Micro emulsion
Field of invention:
The present invention relates to insecticidal formulation of Chlorpyrifos in the form of micro-emulsion and the method of preparing the micro-emulsion. 5
Background of the invention:
The protection of crops from weeds and other vegetation which inhibit crop growth is a constantly recurring problem in agriculture. To help combat this problem researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical 10 compositions effective in the control of such unwanted growth. Chemical insecticides of many types have been disclosed in the literature and a large number are in commercial use.
Water-based pesticide microemulsions have become one of the most potential pesticideformulation instead of the conventional pesticide formulation in recent years, which 15 indeedhave been a good insecticidal performance and a minimal impact on the environment.But thecommonly organic solvents and cosurfactants such as toluene, xylene and methanol werewidely applied in the procession of preparing the formulation. They are detrimental toenvironment and health of human beings all the same. Therefore, controversyover the nocuous additives added excessively, really did put the production and 20 application ofpesticide microemulsion into trouble. But the traditional pesticide formulation can’t becompared with the pesticide microemulsion based on excellent properties of microemulsion insome respects. We should prohibit the addition of toxic substances into microemulsion, ratherthan forbid the pesticide microemulsion formulation itself. The development of pesticidemicroemulsions need providing more equitable space and rational 25 platform.
Chlorpyriphos is organophosphate insecticide, acaracide and miticide that acts by inhibiting acetylcholinesterase. Its IUPAC name is O, O-Diethyl O-3, 5, 6-trichloropyridin-2-yl phosphorothioate. It is used in termite control in agriculture,forestry, buildings and wood 30 care. It has been formulated in various types of formulations such as EC, GR, WG, WP, DP, CS. Each of these formulations have their own limitations of stability and performance. Recently literature has cited limited work on micro emulsion formulations of Chlorpyriphos.
3
CN 1408232A teaches a Chlorpyrifos micro emulsion comprising 10 to 30% by weight chlorpyrifos; 10 to 30% by weight of the surfactant / co-surfactant system; 3 to 15% by weight of co-solvent; 0.5 to 1.5 % by weight stabilizer agent; and the balance being water. The major drawback of said composition is the use of organic co-solvents such as benzene, toluene or xylene and stabilizing agent such as ethanol, isopropanol, ethylene glycol, 5 butanol, or octanol.
CN 1969629A teaches a pesticide containing chlorpyrifos microemulsion containing chlorpyrifos, surface active agents, solvents, stabilizers, water. The weight percentage of 10 to 50% of the chlorpyrifos. The surfactant / co-surfactant is a castor oil ethylene oxide 10 adduct, phenylethyl phenol polyoxyethylene ether, phenylethyl phenol polyoxyethylenepolyoxypropylene ether, phenylethyl phenol polyoxyethylene ether phosphate ester, alkylphenol ether formaldehyde condensate, benzyl biphenolpolyoxyethylene ethers, alkyl phenol ethoxylates, phenol ethoxylates Union, alkylbenzenesulfonates, C8-C20- alkyl sodium salt, styrene laureth sulfate salts. In one or a 15 mixture of two, the weight percentage of 10 ~ 30%. The co-solvent is ethanol, isopropanol, n-butanol, n-pentanol, hexanol, acetone, cyclohexanone, dimethylformamide, cyclohexane, benzene, toluene, xylene, alkylnaphthalenes, the weight percentage of 1 ~ 10%. The stabilizer is 2-propylene oxide, butyl glycidyl ether, polyethylene group ethylene glycol diglycidyl ether, sorbitol, isopropanol, n-butanol, ethylene glycol, polyethylene glycol, urea, 20 propylene glycol, glycerin, turpentine, the weight percentage of 0.1 to 5%. And the remaining amount of water or deionized water. The major drawback of said composition is the use of undesirable organic solvents as discussed above.
US 20140100196 A1 teaches a phytosanitary microemulsion, wherein such active ingredient 25 is chloropyrifos and the microemulsion comprises: 25% of 100% technical grade chloropyrifos; 36.10% of refined soy oil; 4.00% of a surfactant; 0.20% of a biocide; 2.00% of bidistilledglycerine; 4.40% of xanthan gum a 2% in water, and31.80% of water. The major drawback of said composition is the use of undesirable organic solvents as discussed above. 30
As discussed above, the formulations in the prior art in liquid form emulsifiable concentrates use aromatic solvents which are corrosive, have fire hazards and may cause pitting on painted surfaces and have poor penetration. The capsule suspension formulation though
4
having long residual action had stability issues and the spreading and penetration were less effective. The formulations in powder form has low release rate. Dampness causes clogging and lumping in powder formulations. In powder formulations the even distribution of particles on surfaces is difficult. Powder formulation because of dusty nature may irritate eyes, nose, throat and skin. 5
CN 104012527B teaches microemulsion formulation of chlorpyrifos, in particular to a dosage form performance. The composition ofchlorpyrifos, comprising 10-50% chlorpyrifos, emulsifiers 15-25%, 5-15% cosolvent, balance water. Said micro-emulsion composition is water-based, reducing the use of aromatic organic solvents, and maximize the use of 10 environmentally friendly organic solvents, reducing agents on human and animal toxicity and irritation, reducing the formulation of crop damage, reduce environmental pollution, improve the formulation of safe use.
US 4388297 teaches a stable insecticidally active composition which is in the form of a 15 solution which is dispersible in water to form a stable emulsion and which comprises the about 1 to about 50 percent by weight of total composition of chlorpyrifos, about 10 to about 80 percent by weight of total composition of a Castor Oil based nonionic surfactant containing from about 5 to about 55 moles of ethylene oxide chemically combined with each mole of Castor Oil and from about 5 to about 50 percent by weight of total composition of 20 an anionic surfactant.
The formulation of pesticide microemulsion is an inexact science and eludes prediction forthe most part, and largely dependent upon specific and incompletely understood interactionbetween the molecules of oil, emulsifiers, and water. 25
Thus there remains a need in the art to develop new microemulsion composition of Chloropyriphosthat exhibits synergism and good bio-efficacy against wide varieties of pests, having eco-friendly components.
30
Thus the object of the present invention is to provide a novel insecticidal formulation comprising Chlorpyrifos in the form of micro-emulsion and the method of preparing the micro-emulsion.
5
Summary of the Invention:
In order to achieve the afore-mentioned objective the present invention provides a novel insecticidal formulation comprising Chlorpyrifos in the form of micro-emulsion and the method of preparing the micro-emulsion. 5
According to one of the aspect of the present invention teaches the microemulsion of Chlorpyriphos containing 1% to 25%m/m in the formulation. Said formulation is prepared by the titration method. Further, based on the solubility of chlorpyriphos, aromatic hydrocarbon is selected as internal phase. Co-solvent is selectedon solubility of chlorpyriphos and the 10 surfactant. Surfactant and co-surfactant are selected on the basis of chlorpyriphos solubility,safety and stability profile.
Different ratios of surfactant/co-surfactant and solvent-co-solvent were studied. Formation of microemulsion was characterized by dilution test, dye solubility test,globule size 15 determination. Chlorpyriphos microemulsion were prepared by taking chlorpyriphos ranging from 1% to 25% m/m in the formulation. Chlorpyriphos was dissolved in solventaromatic hydrocarbon or vegetable oil ester and a low molecular weight alcohol was taken as co solvent. The quantity of solvent and co-solvent varied from 5% - 25%m/m. Surfactant and co-surfactant (10 – 20%m/m) of the total required qty of surfactant were dissolved in 20 demineralized water to form the aq. continuous phase. Balance qty of surfactant and co surfactant were added in the oil phase. Organic phase was slowly added in the aqueous phase to form micro emulsion.
Detailed description of the Invention: 25
The present invention relates to an insecticidal composition of Chlorpyriphos in the form of Micro emulsion.
According to one of the aspect of the invention, the insecticidal composition in the form of 30 microemulsion comprises 1% to 25%m/m Chlorpyriphos, 5% to 15% by weight aromatic hydrocarbon or vegetable oil ester, 1% to 5% by weight co-solvent; 15 to 40% by weight surfactant; and 15 to 30% by weight co-surfactant.
6
According to another aspect of the invention, the aromatic hydrocarbons are selected from xylene and CIX solvent.CIX is a mixture of aromatic hydrocarbons having carbon atoms 9.
There is no CAS no. as it is a mixture and not pure chemically defined product. It is a product from the refinery of IOC/Reliance. It is a distillation fraction from crude oil which contains aromatic hydrocarbons such as tri methyl benzene and its structural analogues. 5
According to another aspect of the invention, the solvents are selected from aromatic hydrocarbons or vegetable oil ester. Vegetable oil ester are methyl esters of soya bean oil, castor oil, etc. and are called green solvents.
10
According to another aspect of the invention, the co-solvents are selected from aliphatic alcohol C4 – C6.
According to another aspect of the invention, the surfactants are selected from nonyl phenol ethoxylate, castor oil ethoxylate, and triglyceride ethoxylates. 15
According to another aspect of the invention, the co-surfactants are selected from anionic surfactants such as sodium dioctyl sulphosuccinate, Nonyl phenol sulphonate sodium salt, Lauryl alcohol ethoxylate sulphonate sodium salt.
20
According to another aspect of the invention, the ratio of surfactants and co-surfactant is 1:1 to 2.5:1. More preferably the ratio of surfactants and co-surfactant is 1.5:1
According to another aspect of the invention, the ratio of solvent and co-solvent is 50:50 to 90:05. 25
According to another aspect of the invention, the formulation is prepared by the titration method.
According to another aspect of the invention, based on the solubility of chlorpyriphos, 30 aromatic hydrocarbon is selected as internal phase. The internal phase is oil and the continuous or external phase is water.
7
According to another aspect of the invention, co-solvent is selectedbased on solubility of chlorpyriphos and the surfactant. Surfactant and co-surfactant are selected on the basis of chlorpyriphos solubility,safety and stability profile.
According to another aspect of the invention, different ratios of surfactant/co-surfactant and 5 solvent-co-solvent were studied.
The compositions realized in accordance with embodiments of the present disclosure exhibits synergistic insecticidal activity in variety of crops.
10
Characterization of microemulsion:
Formation of microemulsion was characterized by dilution test, dye solubility test,globule size determination.
1. Dilution test: Dilution test are based on the fact that the emulsion is only miscible with the liquid that forms the continuous phase. The microemulsion formed is oil in water and 15 the continuous phase is water. On dilution with water it formed a continuous phase and was completely miscible to form a solution.
2. Dye Solubility test: Here a dye is sprinkled on the surface of the emulsion. The dispersion of dye indicate the type of microemulsion. With an o/w emulsion there is a 20 rapid dispersion of water soluble dye in to the system where as with w/o emulsion the dye forms microscopically visible clumps. The microemulsion of chlorpyriphos exhibited rapid dispersion of water soluble dye in the system.
3. Globule size determination: The globule size was determined using photon 25 correlation spectroscopy (PCS) with built in Zetasizer (model: Nano ZS, Malvern instruments,UK). The instrument is based on the principle of dynamic light scattering (DLS). DLS is a technique of measuring the size of particles in the sub – micron region and is usually applied to the measurement of particles suspended with in a liquid. The particle size of the Chlorpyriphos ME was found to be less than 50nm. 30
Process of preparation of CPP micro emulsion:
Chlorpyriphos microemulsion were prepared by taking chlorpyriphos ranging from 1% to 25% m/m in the formulation. Chlorpyriphos was dissolved in solvent aromatic hydrocarbon
8
or vegetable oil ester and a low molecular weight alcohol was taken as co solvent. The quantity of solvent and co-solvent varied from 10% - 20%m/m. Surfactant and co-surfactant (20 – 20%m/m) of the total required qty of surfactant were dissolved in demineralized water to form the aq. continuous phase. Balance qty of surfactant and co surfactant were added in the oil phase. Organic phase was slowly added in the aqueous phase to form micro 5 emulsion.
The present invention will now be explained with the help of the following example and experiment, however; the scope of the invention should not be limited to said example and experiments. It is to be understood that the above described embodiments are merely 10 illustrative principles of the present invention and that many variations may be devised by those skilled in the art without departing from the scope of the present invention. It is, therefore, intended that such variations be included with the scope of the claims.
Example 1: 15
Preparation of oil phase: Chlorpyriphos tech 19 parts was dissolved in 15 parts of solvent (aromatic or vegetable oil ester) and 21 parts of surfactant and 14 parts of co surfactant to form the oil phase.
Preparation of aqueous Phase (continuous phase): 9 parts of surfactant and 6 parts of co surfactant and 2 parts of co-solvent were added to demineralized water to form the 20 continuous phase.
Oil phase was added to the continuous phase slowly under stirring to form the micro emulsion of CPP.
Experiment 1: Bio efficacy of the composition: 25
In an experiment conducted according to embodiments of the present disclosure, the invention aims to improve bio efficacy of Chlorpyriphos in the form of micro emulsion over the conventional formulations prevalent in the form of EC, GR, WP, WG and SC. Bio efficacy trials were conducted to check the effect of micro emulsion formulation in controlling leaf folder in paddy. After spraying the extent of suppression of larval leaf folder and 30 subsequently the extent suppression of damage leaf was checked after 4 days of spraying. Results are as summarized below:
9
Extent of suppression of leaf folder (Cnaphalocrocis medinalis) population by the different formulation of Clorpyrifos in the field of paddy at Tohana, Haryana
Table: Extent of suppression of Larval Leaf folder and Damage leaf incidence infestation
Treatments
Extent of population suppression (% Larval Leaf folder/hill)
Extent of suppression of damage leaf (% Incidence of Damaged leaf)
4 Days after application
4 Days after application
Clorpyrifos 20EC @ 1875 ml/ha
34.98
46.03
Clorpyrifos 19 ME @ 400 ml/ha
63.56
62.44
Clorpyrifos 19 ME @ 600 ml/ha
85.45
81.31
Clorpyrifos 19 ME @ 800 ml/ha
86.35
82.54
Untreated control
7.98
7.26
5
In consideration of Larval population:
Larval population were noted in each plot at 4 Days after application of treatments. At the time of observation 10 hills were randomly selected from each plot and from that average incidence of larval population were recorded and calculated in percent value.
In consideration of leaf damage incidence: 10
Extent of infestation by counting the number of leaves per 10 hills having more than 1/3 rd damage leaf area were observed after 4 days of application and calculated in percent value.
Conclusion:
1. Clorpyriphos 19 ME at the dose of 600 & 800 ml/ha given good control in the suppression of Larval leaf folder and incidence of damage leaf as compared to 15 Clorpyrifos 20 EC @ 1875 ml/ha.
2. There were no significant difference in between the Clorpyrifos ME dose @ 600 & 800 ml/ha.
3. No phytotoxicity was observed in any one of the treatment.
20
Any embodiments which could be reached by the motivation or teachings of the specification of this invention, but not be explained by this specification will fall within the scope of this invention.
Advantages and usefulness of the proposed invention: 25
10
The present invention of Chlorpyriphos in micro emulsion form has a much lower mean diameter of droplet as compared to Macro emulsion, suspension concentrates, wettable powders, capsulated suspensions and thus yielded much higher and effective coverage of the active matter on the surface applied. With the reduction in mean diameter the number of particles with the same quantity of chlorpyriphos are higher and this leads to better 5 effective coverageand bio efficacy with less quantity on chlorpyriphos.
The formulation is thermodynamically stable and requires minimum energy for formation. It is easy to formulate and scale up.

We claim:
1. An insecticidal composition in the form of microemulsion comprising:
- 1% to 25%m/m Chlorpyriphos;
- 5% to 15% by weight aromatic hydrocarbon or vegetable oil ester; 5
- 1% to 5% by weight co-solvent;
- 15 to 40% by weight surfactant; and
- 15 to 30% by weight co-surfactant.
2. The insecticidal composition as claimed in claim 1, wherein the aromatic hydrocarbons are 10 selected from xylene and CIX solvent.
3. The insecticidal composition as claimed in claim 1, wherein the solvents are selected from aromatic hydrocarbons or vegetable oil ester.
15
4. The insecticidal composition as claimed in claim 3, wherein the vegetable oil ester are methyl esters of soya bean oil, castor oil, etc.
5. The insecticidal composition as claimed in claim 1, wherein the co-solvents are selected from aliphatic alcohol C4 – C6. 20
6. The insecticidal composition as claimed in claim 1, wherein the surfactants are selected from nonyl phenol ethoxylate, castor oil ethoxylate, and triglyceride ethoxylates.
7. The insecticidal composition as claimed in claim 1, wherein the co-surfactants are selected 25 from anionic surfactants such as sodium dioctyl sulphosuccinate, Nonyl phenol sulphonate sodium salt, Lauryl alcohol ethoxylate sulphonate sodium salt.
8. The insecticidal composition as claimed in claim 1, wherein theratio of surfactants and co-surfactant is 1:2 to 2.5:1. 30
9. The insecticidal composition as claimed in claim 1, wherein the ratio of surfactants and co-surfactant is1.5:1.
10. The insecticidal composition as claimed in claim 1, wherein theratio of solvent and co-solvent 35 is 50:50 to 90:05.
12
11. A process of preparing the insecticidal composition in the form of microemulsion comprising the steps of:
1. dissolving Chlorpyriphos tech in solvent (aromatic or vegetable oil eastr), surfactant and co surfactant to form the oil phase; 5
2. adding surfactant, co surfactant and co-solvent to dimineralised water to form the continuous phase;