1
FORM 2
THE PATENTS ACT 1970
(39 Of 1970)
And
THE PATENT RULES, 2003 (See Section 10, rule 13)
COMPLETE SPECIFICATION
(See Section l0)
IMPROVED STORAGE STABLE COMPOSITIONS OF MUTUALLY INCOMPATIBLE INSECTICIDES AND A PROCESS FOR ITS
PREPARATION
UNITED PHOSPHORUS LTD., A COMPANY REGISTERED UNDER INDIAN COMPANY'S ACT 1956, HAVING ITS REGISTERED OFFICE AT 3 -11, GIDC, VAPI - 396 195, STATE OF GUJARAT, INDIA
The following specification particularly describes the invention and the manner in which it is to be performed :
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Technical Field of the Invention
The present invention relates to improved storage-stable composition of mutually incompatible insecticides and a process for its preparation. The present invention relates more particularly relates to improved storage-stable composition of mutually incompatible insecticides, the insecticides being selected from a chloronicotynyle compound and an organophosphorus compound. The present invention more specifically relates to improved storage stable composition of imidacloprid as the chloronicotynyle compound and acephate or phosphamidon as the organophosphorus compounds, the combinations of which are known for their mutual incompatibility in the co-formulations due to their pH sensitivity, where imidacloprid requires an alkaline environment for stability and the organophosphorus compound acephate or phosphamidon require an acidic environment.
The present invention also relates to a process for the preparation of the improved storage stable composition of mutually incompatible insecticides
Prior art
The two components of the stable synergistic combination namely, imidacloprid and acephate or phosphamidon are each known members of the class of chloronicotynyle and organophosphorus insecticides respectively.
Organophosphorus insecticides are relatively unstable molecules and tend to decompose readily, particularly when exposed to high or low pH. The organophosphorus compound, acephate is more stable at acidic pH and undergoes rapid degradation in alkaline conditions. It also undergoes hydrolysis in the presence of water. On the other hand, chloronicotynyle compounds especially imidacloprid are known for their sensitive nature. Imidacloprid is photosensitive, degrades rapidly in the presence of moisture and is stable only in alkaline pH, degrading in acidic conditions. For all these reasons both acephate and imidacloprid are not able to exhibit stability individually and have difficulties when formulated together as a combination.
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It is known in the prior art that the chemical stability of formulations of organophosphorous insecticides can be enhanced by the addition of certain materials that reduce the rate of chemical degradation of the active ingredient. U.S. Pat. Nos. 4,380,537; 5,140,019; 5,165,934 and 5,260,312 all disclose improvement of stability of organophosphorous insecticides with solid carriers, such as clays. Specifically, U.S. Pat. No. 4,380,537 discloses an insecticide formulation containing an organophosphorous insecticide, such as chlorpyrifos, on carriers such as montmorillonite or attapulgite, and as a stabilizer for the insecticide between 0.5% and 10% by weight of a lactone. Other stabilizers of organophosphorous insecticides known in the prior art include polyethylene glycol and polypropylene glycol. W. Kelley et al., "Use of Deactivators in Granular Clay Formulations," discloses the use of ethanolamine, ethylene glycol (and dimers thereof), propylene glycol (and dimers thereof), and urea as deactivators for formulations of pesticides on clay-based granules. However, the above stabilized insecticidal formulations are found to have unsatisfactory storage stability.
The synergistic activity for compositions containing a combination of chloronicotynyle compound and organophosphorous compound, specifically imidacloprid and acephate is disclosed in US 2006/0008493. The compositions disclosed include a stabilizer, which though is able to impart limited stability and limited shelf life but there is a need to investigate and solve the problem of stability of such compositions, especially under high temperature conditions.
US Pat No. 5,140,019 has disclosed methods of prevention of decomposition of a combination of a compound which maybe imidacloprid, an organophosphorous compound and a compound selected from polyethyleneglycol, propyleneglycol, ethylene glycol-propyleneglycol co-polymer or a mixture of these compounds. We have found that the said combination is unstable with low storage stability as the two active ingredients interact with each other and decompose.
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US 2006/0293287 relates to improved stability of a combination of acephate and imidacloprid, where the problem of stability of acephate and imidacloprid compositions is studied in detail and the attempts are made to resolve the stability problem of the combination by polymer encapsulation of imidacloprid and finally mixing of the two actives in the composition. Even though stability is attained by this method, the manufacturing process of this method is a relatively complicated and expensive technology that gives inconsistent yields. Also, since the polymer selected for coating is polyethylene glycol, which has to be made molten before use, the process is messy and cumbersome. There is a need for simpler, less expensive and more reliable method, with more uniformity in the stability results especially at high temperatures and for longer time periods, such that atleast a shelf-life of more than 24 months can be attained.
In our copending application no 665 MUM 2005 we have disclosed a storage stable composition for the protection of crops comprising chloronicotyle compound (imidachloropid) and an organophosphorous compound (acephate or Phosmindon) wherein one of the above active ingredients is coated with a water soluble polymer. The water soluble polymet may be selected from PEG 400. PEG 4000, PEG 6000, PEG 8000, PEG 10,000, Polyvinyl chloride, and the like.
It is now understood that besides the extremely sensitive nature of acephate and imidacloprid, an added problem encountered during co-formulating these two compounds is the known incompatibility of these two molecules due to their physicochemical properties which leads to undesirable interactions of the two compounds. Attempts made to stabilize one of the active ingredients in the formulation may not be useful in stabilizing the other compound, and in this case can lead to destabilizing the other compound. Moreover, both these two active ingredients are moisture sensitive and are known to degrade rapidly in the presence of moisture in the composition or the environment. This problem is further aggravated by the water soluble nature of acephate that makes it take up moisture from the surrounding environment and induce the onset of degradation. Therefore, a need exists to render compatible a combined preparation of normally mutually incompatible imidacloprid and acephate, and further stabilize the
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composition of this insecticidal co-formulation demonstrating sufficiently improved storage stability especially at elevated temperatures and for longer time periods such that the composition is stable even under tropical conditions and therefore improving the shelf life.
Objectives of the present invention
The main objective of the present invention is to provides an improved storage stable composition of mutually incompatible insecides, namely an organophosphorus compound and a chloronicotynyle compound, more specifically acephate and imidacloprid, both of which are of extremely sensitive nature normally not exhibiting stability
Another objective of the present invention is to provide an improved storage stable composition of mutually incompatible insecides which has improved shelf-life.
Still another objective of the present invention is to provide an improved storage stable composition of mutually incompatible insecides which is useful for protecting plants selected from the group consisting of cotton, paddy, rice forage crops, sugarcane, cole crops, leafy vegetables, tobacco, tomatoes, potatoes, flowering ornamentals, vine crops and fruit trees.
Yet another objective of the present invention is to provide a process for the preparation of an improved storage stable composition of mutually incompatible insecides, namely an organophosphorus compound and a chloronicotynyle compound, more specifically acephate and imidacloprid, both of which are of extremely sensitive nature normally not exhibiting stability
Yet another objective of the present invention is to provide a process for the preparation of an improved storage stable composition of mutually incompatible insecides , namely an organophosphorus compound and a chloronicotynyle compound, more specifically
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acephate and imidacloprid, both of which are of extremely sensitive nature normally not exhibiting stability which is simple & economical.
The present invention has been developed, due to our sustained R&D undertaken to find out a storage stable composition overcoming the drawbacks of the hitherto composition, and based on our observation that by incorporation of compatibility inducing inert stabilizing agents selected carefully by way of their properties in rendering stable the co-formulation of two incompatible active ingredients, namely, an organophosphorus compound with chloronicotynyle compound, more specifically acephate and imidacloprid, a storage stable composition can be obtained . We have surprisingly found that the use of such compatibility inducing inert stabilizing agents impart synergistic effect rendering the resulting composition of these two otherwise incompatible active ingredients compatible.
We have observed that the compatibility inducing inert stabilizing agents should be hydrophobic in nature and have low moisture content. Such agents are a combination of silicas or modified silicas and anhydrous salts of minerals
Silicas and modified silicas are known for their inert nature. They are also of low moisture grade such that they provide the much required hydrophobic barrier to acephate and imidacloprid, without contributing to increasing the moisture content of the composition. The anhydrous salts of minerals are carefully selected with the intention to improve the water solubility of the composition at the time of use, but at the same time itself not increasing the moisture content of the composition.
SUMMARY OF INVENTION
Accordingly, the present invention provides an improved storage stable insecticidal composition of two mutually incompatible active ingredients which comprises
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a) 0.1 to 5% by weight of a Chloronicotynyle compound of Imidacloprid,
b) 30 to 75% by weight of an Organophosphorus compound selected from acephate and phosphamidon,
c) 0.1 to 45% by weight of at least one compatibility inducing inert stabilizing
agent which is hydrophobic in nature and has low moisture content, selected from a
combination of silica or modified silica and anhydrous salts of minerals and if
required
d) 5 to 40% by weight of at least one agriculturally acceptable inert ingredient selected from the group consisting of conventional agriculturally acceptable carriers and conventional agriculturally acceptable excipients.
The silicas may be selected with low moisture grade such that they function as a much required hydrophobic barrier to acephate and imidacloprid, without contributing to increasing the moisture content of the composition. Examples of such silicas are Aerosil 200 and Aerosil R972. The anhydrous salts of minerals are carefully selected to improve the water solubility of the composition at the time of use, but at the same time itself not increasing the moisture content of the composition. The examples of such salts are anhydrous ammonium sulfate, ammonium phosphate, ammonium nitrate, calcium sulfate, magnesium sulfate, magnesium sulfate, magnesium oxide, and such.
Detailed description of the invention
Imidacloprid is the common name for l-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine, belonging to the class of chloronicotynyle compounds and the insecticidal properties of which have been described, in particular in the "Pests and diseases" reports of the 1990 Brighton Crop Protection Conference, p. 21. Imidacloprid has a pH sensitive nature and unstable in acidic environment. It is stable to hydrolysis at pH5-ll.
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Acephate is the common name for N-[methoxy(methylthio)phosphinoyl]acetamide, belonging to the class of organophosphorus compounds which are known for their high insecticidal and acaricidal activity, as described in as described on page 9 of The Pesticide Manual 10th edition (published by The British Crop Protection Council, 1994) and used as an active ingredient for agricultural insecticide now, because of having effective controlling activities to various pests. As typical of organophosphorus compounds, acephate is a pH-sensitive molecule, unstable to alkalis. It is also photosensitive, unstable to sunlight and also unstable to soil bacteria.
Phosphamidon is the common name for 2-chloro-3-(diethylamino)-l-methyl-3-oxo-l-propenyl dimethyl phosphate also belonging to the class of organophosphorus compounds and is described in on page 803 of The Pesticide Manual 10th edition (published by The British Crop Protection Council, 1994). Commercially it consists of 70% m/m (Z)-isomer (P-isomer) which has greater insecticidal activity and 30% m/m (E)-isomer (a-isomer).
Acephate is unstable in alkaline pH whereas imidacloprid is unstable in acidic pH, and since there is no common pH condition to favor stabilization of the two, it is therefore difficult to formulate the two together. Attempts made to solve this problem by addition of buffering agents into the formulation have been met with limited success. Also, since the rate of hydrolysis for acephate increases with increasing pH and degrades rapidly in alkaline soil, acephate has to be formulated in a way to protect it from degradation. Besides, acephate and imidacloprid both being sensitive molecules show low compatibility and are known to undergo chemical degradation when combined together and exhibit active: active incompatibility resulting in pronounced degradation of the two active ingredients which leads to instability when formulated into a combined preparation.
Attempts to stabilize the composition of the combined preparation of the present invention by the usual means known in the art have been met with limited success. The inventors of the present invention have found that the problem of instability and limited
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shelf life of the co-formulation of imidacloprid and acephate is mainly due to the individual pH sensitivity of each molecule and this could be solved by providing an inert environment to both the active ingredients by the use of silicas.
The silicas are selected in such a way that a mixture of high concentration of colloidal anhydrous silica of normal moisture grade and a small percentage of modified silica of low moisture grade are used. Aerosil 200 is selected as the colloidal anhydrous silica of the normal moisture content of about 5 to 6% which acts in providing an inert environment to the combination of imidacloprid and acephate. Aerosol R972 is selected as the modified silica with low moisture content of not more than 0.5%. Owing to the property of considerably low particle size and low bulk density, this modified silica has a significantly large surface area, therefore even when used in low concentrations has very high effectiveness. The anhydrous salt of the minerals such as anhydrous ammonium sulfate is known for its water solubility and to the composition is added for its water soluble properties.
In a preferred embodiment of the invention the compatibility inducing inert stabilizing agent used may be selected from the group of silicas, silicates, modified silicas, fumed silicas and silicic acids. The stabilized insecticidal composition may also contains surfactants, stabilizers, dispersing agents, emetic agents, antifoaming agent, disintegrating agents, anti-caking agents, binding agents, dyes and inert fillers. The surfactant used may be selected from the group consisting of non-ionic surfactants, cationic surfactants and anionic surfactants.
The anionic surfactants used may be selected from a group consisting of alkali metal soaps, alkaline earth metal soaps, substituted or unsubstituted ammonium salts of higher fatty acids, the sodium or potassium salt of oleic or stearic acid, and natural fatty acid mixtures.
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The stabilizer used may be selected from the group consisting of ethoxylates of vegetable oil, salts of higher fatty acids, a blend of the derivatives of epoxylated vegetable oil, ethoxylated polyoxyethylene amine, pyrrolidine, and lactone.
The dispersing agent used may be formaldehyde condensate of alkyl phenols. The emetic agent used maybe a lignocaine derivative or a formulation of lignocaine derivative. The antifoaming agent used may be a silicone oil derivative. The disintegrating agent used may be selected from a group consisting of bentonite clay, Zeolite clay, Attapulgite clay, sodium sulphate slats, and aluminum sulphate salts. The filler used may be selected from a group consisting of kaoline, and clay. The anticaking agent used may be selected from the group consisting of a blend of sucrose and starch derivatives. The binding agent used may be a pyrrolidine derivative. The dye used may be a water soluble dye or a water insoluble dye.
The acephate used may be of Technical grade acephate having a minimum of 97% purity, the imidacloprid used may be Technical grade imidacloprid having a minimum of 95% purity and the phosphamidon used may be of Technical grade phosphamidon having a minimum of 92% purity.
The composition may be in a powder form, having preferably an average particle size of 2-1500 microns. The composition may also be in the form of granules or pellets having an average particle size of 0.8 -1.2mm.
Compositions in solid form which may be mentioned are powders for dusting or dispersion and granules, especially those obtained by extrusion, by compacting, by impregnation of a granular support or by granulation from a powder (with a content of combination according to the invention which may range from 30.1% to up to 80%).
According to another embodiment of the invention there is provided a process for the stabilized insecticidal composition defined above which comprises mixing thoroughly 0.1 to 5 % by weight a Chloronicotynyle compound of Imidacloprid, 30 to
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75% by weight an Organophosphorus compound selected from the group consisting of Acephate and Phosphamidon, 0.1 to 45% by weight of compatibility inducing inert stabilizing agent which is hydrophobic in nature and has low moisture content, which is a combination of silica or modified silica and anhydrous salts of minerals and if required, 5 to 40% by weight of at least one agriculturally acceptable inert ingredient selected from the group consisting of conventional agriculturally acceptable carriers and conventional agriculturally acceptable excipients.
The agriculturally acceptable inert compound may be selected from the group consisting of mineral earth like silicas, silica gels, silicates, talc, kaolin, montmorillonite, attapulgite, pumice, sepiolite, bentonite, limestone, lime, chalk, clay, dolomite, diatomaceous earth, calcite.
The anhydrous salts of minerals may be selected from anhydrous calcium sulfate, magnesium sulfate, magnesium sulfate, magnesium oxide, sand, ground plastics, ferilizers like ammonium sulfate, ammonium phosphate, ammonium nitrate, ureas, cereal meal, tree bark meal, wood meal, nutshell meal, and cellulose powders.
The synergistic insecticidal composition is useful to control agricultural pests, hygienic pests and horticulture pests, to protect plants selected from the group consisting of cotton, paddy, rice forage crops, sugarcane, cole crops, leafy vegetables, tobacco, tomatoes, potatoes, flowering ornamentals, vine crops and fruit trees, to protect plants selected from the group consisting of cotton, paddy, rice forage crops, sugarcane, cole crops, leafy vegetables, tobacco, tomatoes, potatoes, flowering ornamentals, vine crops and fruit trees.
Stabilized synergistic combinations such as those of the present invention result in higher insecticidal activity for a given amount of insecticide and thus make possible control of insects at lower cost. Availability of less expensive insecticides is of major importance in the practical control of insects, particularly pests in the areas of agriculture, household and public uses. But mutual incompatibility of the two active ingredients in the combination and relative instability of the combined preparation would result in losses of
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the active ingredients due to degradation, thus affecting the biological activity as well as leading to the problem of insect resistance.
The details of the invention are given in the Examples given below which are given only torn illustrate the invention and hence they should not be construed to limit the scope of the invention
EXAMPLE 1
53 gms of acephate was blended with 3 gms of imidacloprid and the mixture was studied for stability in temperature conditions of 30°C, 45°C and 54°C for 14 days. The percentage degradation of acephate and imidacloprid was studied in the combination. Table 1: Stability of acephate and imidacloprid mixture
Degradation in 14 days
30°C 45°C 54°C
Acephate (purity 97%) 43.18% 45.73% 56.34%
Imidacloprid (purity 95%) 90.23% 92.00% 95.00%
Significant degradation of acephate and imidacloprid in combination in all conditions of stability was noticed which indicated that the two active ingredients are not compatible and the combination is not storage stable.
EXAMPLE 2
40 gms of phosphamidon was blended with 2 gms of imidacloprid and the mixture was studied for stability in temperature conditions of 30°C, 45°C and 54°C for 14 days. The percentage degradation of phosphamidon and imidacloprid was studied in the combination.
Table 2: Stability of Phosphamidon and Imidacloprid mixture
Degradation in 14 days
30°C 45°C 54°C
Phosphamidon (purity 92%) 40.35% 46.423% 57.02%
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Imidacloprid (purity 95%) 91.01% 92.55% 94.89%
Similarly, significant degradation of both the actives in the combination in all conditions of stability was noticed which indicated that the two active ingredients are not compatible and the combination is not storage stable.

Weighed quantities of pre-ground imidacloprid technical was loaded into a blender to which weighed quantities of modified silica (Aerosil R972) was added and mixed till a homogeneous mixture was attained. This was called part A.
Weighed quantities of acephate technical was separately taken in a pre-blender to which colloidal anhydrous silica (Aerosil 200) and ammonium sulfate anhydrous were added blended thoroughly to form a homogeneous mass. The Aerosil 200, Aerosil R972 & ammonium sulfate anhydrous also act as stabilizer. This pre-blended mass was micronised to attain the desired particle size. This was called part B.
Part B was blended thoroughly in a post blender for 30 minutes to get a uniform mass. Finally part A was blended into part B and further mixed to get a homogenous mixture of all the ingredients.
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The composition of example 3 was studied for AHS stability under various conditions to determine the percentage of degradation of the composition.
Table 3: Stability of acephate and imidacloprid composition in presence of stabilizer at 30°C condition

Acephate Content Imidacloprid Content
%stabilizer Initial 14 days % degradation Initial 14 days % degradation
1 51.08 51.080 Nil 51.08 51.080 Nil
0.8 51.02 50.606 0.81 % 51.02 50.606 0.81 %
0.6 51.04 50.484 1.09% 51.04 50.484 1.09%
0.4 50.85 49.783 2.1% 50.85 49.783 2.1%
0.2 50.98 49.410 3.08 % 50.98 49.410 3.08 %
Table 4: Stability of acephate and imidacloprid composition in presence of stabilizer at 45 °C condition

Acephate Content Imidacloprid Content
%stabilizer Initial 14 days % degradation Initial 14 days % degradation
1 51.08 51.080 Nil 1.804 1.804 Nil
0.8 51.02 50.606 0.81 % 1.810 1.810 Nil
0.6 51.04 50.484 1.09% 1.802 1.795 0.80%
0.4 50.85 49.783 2.1% 1.809 1.789 1.1
0.2 50.98 49.410 3.08 % 1.819 1.775 2.38
Table 5: Stability of acephate and imidacloprid composition in presence of stabilizer at 54°C condition

Acephate Content Imidacloprid Content
%stabilizer Initial 14 days % degradation Initial 14 days % degradation
1 51.08 51.080 Nil 1.804 1.804 Nil
0.8 51.02 50.606 0.81 % 1.810 1.776 1.84%
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0.6 51.04 50.484 1.09% 1.802 1.765 2.04%
0.4 50.85 49.783 2.1% 1.809 1.740 3.8%
0.2 50.98 49.410 3.08 % 1.819 1.702 6.38%
In all the above concentrations of stabilizer the wetting time was found to be greater than 180 minutes.
The presence of the stabilizer in the formulation showed significantly less degradation under all conditions of stability. Increasing concentrations of stabilizer in the formulation showed decrease in degradation of acephate and imidacloprid. The most suitable range for maximum effect of stabilizer was found to be at the range of 0.6-1.0 %.
EXAMPLE 6
The composition of example 4 was altered to use ordinary precipitated silica instead of
modified silica to compare the effect of higher moisture content of silica on the stability
of the composition.
Ingredient Quantity (%w/w)

Imidacloprid technical (purity 95%) Acephate technical (purity 97%) Precipitated silica Ammonium sulfate anhydrous
Total

1.8948
52.577 10.800 34.728
100.00 (w/w)

Weighed quantities of pre-ground imidacloprid technical was loaded into a blender to which half the total quantity of precipitated silica was added and mixed till a homogeneous mixture was attained. This was called part A.
Weighed quantities of acephate technical was separately taken in a pre-blender to which the remaining quantity of precipitated silica and ammonium sulfate anhydrous were added blended thoroughly to form a homogeneous mass. This pre-blended mass was micronised to attain the desired particle size. This was called part B
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Part B was blended thoroughly in a post blender for 30 minutes to get a uniform mass. Finally part A was blended into part B and further mixed to get a homogenous mixture of all the ingredients.
Table 6: Stability of acephate and imidacloprid composition using ordinary precipitated silica.

Temperature Condition Acephate Content Imidacloprid Content
Initial 14 days % degradation Initial 14 days % degradation
30°C 51.03 34.191 33.00% 1.800 0.180 90.00%
45°C 51.03 28.475 44.20% 1.800 0.136 92.4 %
54°C 51.03 25.942 49.16% 1.800 0.097 94.56%
Ordinary precipitated silica which is known to have a moisture content of about 6-7% was used instead of modified silica to check the effect of moisture in the silica on the degradation of the active ingredients. This example is a comparitive example to show that precipitated silica, the acephate and imidacloprid showed increasing degradation, thereby indicating that the presence of moisture in the silica affected the stability of the composition.
EXAMPLE 7
Anhydrous ammonium sulfate was used in the composition of Example 3 but in the
absence of silicas to compare with the effect of anhydrous ammonium sulfate alone in the
absence of silicas.
Ingredient Quantity (%w/w)

Imidacloprid technical (purity 95%) Acephate technical (purity 97%) Ammonium sulfate anhydrous
Total

1.8948
52.577 45.528
100.00 (w/w)

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Weighed quantities of pre-ground imidacloprid technical was loaded into a blender to
which half the total quantity of precipitated anhydrous ammonium sulfate was added and
mixed till a homogeneous mixture was attained. This was called part A.
Weighed quantities of acephate technical was separately taken in a pre-blender to which
the remaining quantity of ammonium sulfate anhydrous was added blended thoroughly to
form a homogeneous mass. This pre-blended mass was micronised to attain the desired
particle size. This was called part B.
Part B was blended thoroughly in a post blender for 30 minutes to get a uniform mass.
Finally part A was blended into part B and further mixed to get a homogenous mixture of
all the ingredients.
Table 7: Stability of Acephate and Imidacloprid composition using ordinary precipitated silica.

Temperature Condition Acephate Content Imidacloprid Content
Initial 14 days % degradation Initial 14 days % degradation
30°C 51.03 34.191 33.00% 1.800 0.180 90.00%
45°C 51.03 28.475 44.20% 1.800 0.136 92.4 %
54°C 51.03 25.942 49.16% 1.800 0.097 94.56%
Ordinary silica which was not used in the composition and it was instead compensated with anhydrous ammonium sulfate. This was done to check the effect of silica in the composition on the degradation of the active ingredients. Absence of silica showed pronounced degradation of both acephate and imidacloprid, thereby indicating that the presence of silica along with anhydrous ammonium sulfate stabilizes the composition due to synergism.
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EXAMPLE 8
Ingredient Quantity (%w/w)
Imidacloprid technical (purity 95%) 2.1053
Phosphamidon technical (purity 92%) 43.4783
Aerosil 200 10.000
AerosilR972 0.8000
Ammonium sulfate anhydrous 43.6164
Total 100.00 (w/w)
Weighed quantities of pre-ground imidacloprid technical was loaded into a blender to
which weighed quantities of modified silica (Aerosil R972) was added and mixed till a
homogeneous mixture was attained. This was called part A.
Weighed quantities of colloidal anhydrous silica (Aerosil 200) and ammonium sulfate
anhydrous were taken in a pre-blender to which and phosphamidon technical was sprayed
while mixing and blended thoroughly to form a homogeneous mass. This pre-blended
mass was micronised to attain the desired particle size. This was called part B.
Part B was blended thoroughly in a post blender for 30 minutes to get a uniform mass.
Finally part A was blended into part B and further mixed to get a homogenous mixture of
all the ingredients.
EXAMPLE 9
The composition of Example 8 was studied for AHS stability under various conditions to
determine the percentage of degradation of phosphamidon and imidacloprid.
Table 8: Stability of Phosphamidon and Imidacloprid composition in presence of
stabilizer

%Stabilizer Phosphamidon Degradation in 14 days Imidacloprid Degradation in 14 days
30°C 45°C 54°C 30°C 45°C 54°C
1 Nil Nil 2.55 % Nil Nil Nil
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0.8 0.88 % 1.44% 3.78% Nil Nil 1.90%
0.6 1.50% 2.35% 4.41 % Nil 0.86% 2.00%
0.4 2.23% 3.91 % 5.42% Nil 1.02 3.76%
0.2 3.15% 6.03 % 8.46% 1.10 2.61 6.96%
NIL 32.63% 45.02% 57% 91.05% 93.3 % 95.00%
The presence of the stabilizer in the formulation showed significantly less degradation under all conditions of stability. Increasing concentrations of stabilizer in the formulation showed decrease in degradation of phosphamidon and imidacloprid. The most suitable range for maximum effect of stabilizer was found to be in the range of 0.6-1.0 %.
EXAMPLE 10
To the composition of Example 3 a wetting agent namely di isopropyl naphthalene
sulfonate sodium salt as the brand name Supragil WP was added to check the effect of
wetting agent on the wettability of the composition and the effect of the wetting agent on
the degradation of the active ingredients of the composition.
Ingredient Quantity (%w/w)

Weighed quantities of pre-ground imidacloprid technical was loaded into a blender to which weighed quantities of modified silica (Aerosil R972) was added and mixed till a homogeneous mixture was attained. This was called part A.
Weighed quantities of acephate technical was separately taken in a pre-blender to which colloidal anhydrous silica (Aerosil 200), di isopropyl naphthalene sulfonate sodium salt (Supragil WP) and ammonium sulfate anhydrous were added blended thoroughly to form
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a homogeneous mass. This pre-blended mass was micronised to attain the desired particle
size. This was called part B.
Part B was blended thoroughly in a post blender for 30 minutes to get a uniform mass.
Finally part A was blended into part B and further mixed to get a homogenous mixture of
all the ingredients.
Table 9: Wettability of composition in the presence varying amounts of wetting agent and
effect of wetting agent on degradation of acephate and imidacloprid.

% Wetting agent in formulation Degradation in 14 days at 54°C Wettability in seconds
Acephate Imidacloprid
Nil 2.02% Nil > 180 minutes
5% 2.89% 1.38% > 180 minutes
10% 5.13% 8.38% 100 minutes
15% 44% 36% 25 minutes
20% 60% 98% 45 seconds
The stability studies indicated that even though the presence of wetting agent improved the wettability of the composition, it enhanced the degradation of the active ingredients. Therefore the use of wetting agent was found to be detrimental to the stability of the composition. Similar wettability and degradation was observed for combined preparations of phosphamidon and imidacloprid.
Advantages of the present invention
1. Provides a storage stable composition of a combined preparation of an
organophosphorous compound with chloronicotynyle compound, more specifically
acephate and imidacloprid, both of which are of extremely sensitive nature normally not
exhibiting stability.
2. The composition has improved shelf-life.
3. The method of manufacturing the stabilized composition is simple & economical.
4. The composition is useful for protecting plants selected from the group consisting of cotton, paddy, rice forage crops, sugarcane, cole crops, leafy vegetables, tobacco, tomatoes, potatoes, flowering ornamentals, vine crops and fruit trees.
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We claim
1. An improved storage stable insecticidal composition of two mutually
incompatible active ingredients comprising
a) 0.1 to 5% by weight of a Chloronicotynyle compound of Imidacloprid,
b) 30 to 75% by weight of an Organophosphorus compound selected from acephate and phosphamidon,
c) 0.1 to 45% by weight of at least one compatibility inducing inert stabilizing agent, which is hydrophobic in nature and has low moisture content, selected from a combination of silica or modified silica and anhydrous salts of minerals and if desired
d) 5 to 40% by weight of at least one agriculturally acceptable inert ingredient selected from the group consisting of conventional agriculturally acceptable carriers and conventional agriculturally acceptable excipients.
2. The stabilized insecticidal composition of claim 1 wherein the
compatibility inducing inert stabilizing agent which is hyrdrophobic in nature is modified
silica with a moisture content of not more than 0.5%.
3. The stabilized insecticidal composition of claim 1 wherein the agriculturally
acceptable inert ingredients is selected from the group consisting of talc, kaolin,
montmorillonite, attapulgite, pumice, sepiolite, bentonite, limestone, lime, chalk, clay,
dolomite, diatomaceous earth and calcite.
4. The stabilized insecticidal composition of claims 1 wherein the anhydrous
salts of minerals is selected from calcium sulfate, magnesium sulfate, magnesium sulfate,
magnesium oxide, sand, ammonium sulfate, ammonium phosphate, ammonium nitrate.
5. The stabilized insecticidal composition of claims 1 to 4 wherein the
composition contains surfactants, stabilizers, dispersing agents, emetic agents,
antifoaming agent, disintegrating agents, anti-caking agents, binding agents, dyes and
inert fillers.
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6. The stabilized insecticidal composition of claim 5 wherein the surfactant used
is selected from the group consisting of non-ionic surfactants, cationic surfactants and
anionic surfactants.
7. The stabilized insecticidal composition of claim 5 wherein the anionic surfactants used are selected from a group consisting of alkali metal soaps, alkaline earth metal soaps, substituted or unsubstituted ammonium salts of higher fatty acids, the sodium or potassium salt of oleic or stearic acid, and natural fatty acid mixtures.
8. The stabilized insecticidal composition of claim 5 wherein the stabilizer used is selected from the group consisting of ethoxylates of vegetable oil, salts of higher fatty acids, a blend of the derivatives of epoxylated vegetable oil, ethoxylated polyoxyethylene amine, pyrrolidine, and lactone.
9. The stabilized insecticidal composition of claim 5 wherein the dispersing agent
is formaldehyde condensate of alkyl phenols.
10. The stabilised insecticidal composition of claim 5 wherein the emetic agent used is a lignocaine derivative or a formulation of lignocaine derivative.
11. The stabilized insecticidal composition of claim 5 wherein the antifoaming agent used is a silicone oil derivative.
12. The stabilized insecticidal composition of claim 5 wherein the disintegrating agent used is selected from a group consisting of bentonite clay, Zeolite clay, Attapulgite clay, sodium sulphate slats, and aluminum sulphate salts.
13. The stabilized insecticidal composition of claim 5 wherein the filler used is selected from a group consisting of kaoline, and clay.
14. The stabilized insecticidal composition of claim 5 wherein the anticaking
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agent used is selected from the group consisting of a blend of sucrose and starch derivatives.
15. The stabilized insecticidal composition of claim 5 wherein the binding agent used is a pyrrolidine derivative.
16. The stabilized insecticidal composition of claim 5 wherein the dye used is a water soluble dye or a water insoluble dye.
17. The stabilized insecticidal composition of claims 1 to 16 wherein the Acephate used is Technical grade Acephate having a minimum of 97% purity.
18. The stabilized insecticidal composition of claims 1 to 16 wherein the Imidacloprid used is Technical grade Imidacloprid having a minimum of 95% purity.
19. The stabilized insecticidal composition of claims 1 to 16 wherein the Phosphamidon is Technical grade Phosphamidon having a minimum of 92% purity.
20. The stabilized insecticidal composition of claims 1 to 19, wherein the composition is in a powder form, having preferably an average particle size of 2-1500 microns.
21. The stabilized insecticidal composition of claim 20, wherein the composition is in the form of granules or pellets having an average particle size of 0.8 -1.2mm.
22. The process for the stabilized insecticidal composition of claim 1 which comprises mixing thoroughly 0.1 to 5 % by weight a Chloronicotynyle compound of Imidacloprid, 30 to 75% by weight an Organophosphorus compound selected from the group consisting of Acephate and Phosphamidon, 0.1 to 45% by weight of a compatibility inducing inert stabilizing agent which is hydrophobic in nature and has low moisture content, selected from a combination of silica or modified silica and
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anhydrous salts of minerals and if required, 5 to 40% by weight of at least one agriculturally acceptable inert ingredient selected from the group consisting of conventional agriculturally acceptable carriers and conventional agriculturally acceptable excipients.
23. The process of claim 22 wherein at least one inert agriculturally acceptable compound is selected from the group consisting of mineral earth like silicas, silica gels, silicates, talc, kaolin, montmorillonite, attapulgite, pumice, sepiolite, bentonite, limestone, lime, chalk, clay, dolomite, diatomaceous earth, calcite.
24. The process of claim 22 wherein the anhydrous salts of minerals are selected from calcium sulfate, magnesium sulfate, magnesium sulfate, magnesium oxide, sand, ground plastics, ferilizers like ammonium sulfate, ammonium phosphate, ammonium nitrate, ureas, cereal meal, tree bark meal, wood meal, nutshell meal, and cellulose powders.

25. An improved storage stable insecticidal composition of two mutually incompatible active ingredients substantially as herein described with reference to the Examples 3 & 8.
26. A process for the preparation of an improved storage stable insecticidal composition of two mutually incompatible active ingredients substantially as herein described with reference to Examples 3 & 8.

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ABSTRACT
IMPROVED STORAGE STABLE COMPOSITIONS OF MUTUALLY
INCOMPATIBLE INSECTICIDES AND A POROCESS FOR ITS
PREPARATION
The invention disclosed in this application relates to an improved storage stable insecticidal composition of two mutually incompatible active ingredients comprising a Chloronicotynyle compound of Imidacloprid, an Organophosphorus compound selected from acephate and phosphamidon, one compatibility inducing inert stabilizing agent, which is hydrophobic in nature and has low moisture content, selected from a combination of silica or modified silica and anhydrous salts of minerals and if desired at least one agriculturally acceptable inert ingredient.
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