Description:

FIELD OF INVENTION
[0001] The present invention relates to the field of agrochemical formulations, and more particularly to herbicidal microemulsion (ME) compositions. Specifically, the invention concerns a microemulsion formulation comprising Fomesafen, Clodinafop-propargyl, and Imazethapyr for broad-spectrum control of monocotyledonous and dicotyledonous weed species.
BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Weed management remains one of the most persistent and critical challenges in modern agriculture. Weeds compete aggressively with crops for essential resources such as water, nutrients, and sunlight, ultimately resulting in substantial reductions in crop yield and quality. The problem is exacerbated by the evolution of herbicide-resistant weed biotypes and the increasing pressure to minimize environmental impact while maintaining agricultural productivity. To address the issue of weed control, various classes of herbicides are utilized for both pre-emergence and post-emergence applications. Notably, diphenyl ethers (such as Fomesafen), aryloxyphenoxypropionates (like Clodinafop-propargyl), and imidazolinones (for example, Imazethapyr) are commonly used due to their effectiveness against a wide range of weed species. Fomesafen is mainly used to control broadleaf weeds and some grasses, while Clodinafop-propargyl is particularly effective against grassy weeds in cereal crops. Imazethapyr, on the other hand, offers control over a broad spectrum of both grasses and broadleaf weeds in leguminous crops. When used together, these herbicides can create synergistic effects and provide broader control, enhancing agronomic performance while reducing the risk of resistance development. Despite their complementary weed control profiles, these active ingredients are usually formulated and applied separately. This separation stems from challenges related to their chemical incompatibility, differences in solubility, and formulation stability issues when combined. Conventional formulation technologies, such as emulsifiable concentrates (ECs) and suspension concentrates (SCs), often struggle to address these limitations. These traditional systems may experience phase separation, sedimentation, volatility, phytotoxicity, poor rainfastness, and environmental safety concerns, which hinder their effectiveness and sustainability.
[0004] Recently, microemulsion (ME) technology has emerged as a promising alternative to conventional formulations. Microemulsions are thermodynamically stable, isotropic mixtures of oil, water, surfactants, and co-surfactants. They are characterized by their clear appearance, small droplet size, low interfacial tension, and enhanced solubilizing capabilities. These properties lead to improved bioavailability of active ingredients, reduced use of organic solvents, and better spreading and penetration on plant surfaces, all of which enhance herbicidal efficacy. Furthermore, the inherent stability of microemulsions across a wide range of temperatures and storage conditions makes them attractive for agricultural applications.
[0005] The prior art document CN1297195C explains an herbicidal composition comprising fomesafen and imazethapyr, wherein the weight percentage of fomesafen is from 1% to 89%, and the weight percentage of imazethapyr is from 1% to 89%, with the combined weight percentage of fomesafen and imazethapyr ranging from 2% to 90%. The composition may be formulated as a wettable powder, suspension concentrate, emulsifiable concentrate, dust, granule, dry suspension, or aqueous solution. The formulation is primarily intended for the control of common weeds in soybean fields, providing the advantages of a broad weed control spectrum, high efficacy at low application rates, and reduced environmental impact, thereby offering significant benefits for sustainable agricultural production.
[0006] The prior art WO2020/126584 A1 discloses herbicidal combinations comprising R-imazamox with herbicides from different classes, including PPO inhibitors (e.g., fomesafen) and ACCase inhibitors (e.g., clodinafop-propargyl), thereby covering triple combinations such as R-imazamox + fomesafen + clodinafop-propargyl. In contrast, the present invention employs imazethapyr in place of R-imazamox, in defined proportions with fomesafen and clodinafop-propargyl.
[0007] The patent US20210360922A1 generally discloses herbicidal compositions comprising saflufenacil, napropamide (or its enantiomer napropamide-M), and an additional herbicide selected from a broad range of chemical classes. Among the herbicides encompassed are clodinafop-propargyl, fomesafen, and imazethapyr. However, the disclosure does not specifically exemplify or claim the precise three-component combinations of any of the aforementioned herbicides, nor does it define or optimize exact ratios among these components.
[0008] Despite the commercial use of binary herbicide premixes, the ternary combination of Clodinafop-propargyl, Fomesafen, and Imazethapyr remains untested. Existing studies cover Clodinafop with Fomesafen plus Chlorimuron-ethyl, or Fomesafen with Imazethapyr, but not this exact triple mix. Since Imazethapyr and Chlorimuron-ethyl share an ALS (Acetolactate Synthase) mode of action but differ chemically, their interchangeability in mixtures cannot be assumed. This presents a clear research opportunity to evaluate synergy, crop safety, and formulation stability, potentially leading to patentable innovations in weed control. Given these advantages, there is a need to develop a single, stable microemulsion formulation that combines Fomesafen, Clodinafop-propargyl, and Imazethapyr. Such a formulation would enable simultaneous, broad-spectrum weed control through a synergistic mechanism of action, while addressing the formulation and application challenges posed by conventional technologies. Achieving this goal could significantly enhance agronomic performance, improve operational efficiency for farmers, and contribute to more sustainable and integrated weed management practices across various cropping systems.

OBJECTS OF THE INVENTION
[0009] It is the object of the present disclosure to provide a stable, homogeneous, and clear microemulsion formulation containing Fomesafen in an amount of about 10–50% w/w, Clodinafop-propargyl of about 5–30% w/w, and Imazethapyr of about 1–10% w/w.
[0010] It is the object of the present disclosure to provide an herbicidal composition with synergistic activity against a broad spectrum of monocot and dicot weeds.
[0011] It is the object of the present disclosure to improve formulation stability, rainfastness, and target site delivery of active ingredients.
SUMMARY OF THE INVENTION
[0012] The present disclosure relates to an herbicidal microemulsion (ME) formulation comprising three active ingredients with demonstrated synergistic herbicidal activity: Fomesafen (10–50% % w/w), Clodinafop-propargyl (5–30% w/w), and Imazethapyr (1–10% w/w). The formulation further includes: Castor oil ethoxylate (20% w/w), serving as a non-ionic surfactant to facilitate microemulsion formation and ensure physicochemical stability; A fatty acid amide mixture, employed as a co-solvent system to enhance solubilization and dispersion of the active components; Water, functioning as the continuous phase of the microemulsion system.
[0013] The aspects of the present invention relates to the above-mentioned specific combination of active ingredients exhibits broad-spectrum weed control, effectively targeting both monocotyledonous (grass) and dicotyledonous (broadleaf) weed species. Experimental evidence indicates a synergistic interaction among the components, resulting in enhanced herbicidal efficacy compared to individual or binary mixtures. The formulation is characterized by its thermodynamically stable and optically transparent microemulsion system, which facilitates improved solubilization and bioavailability of the active compounds, thereby contributing to superior field performance and consistent weed management.
[0014] The aspects of the present disclosure provide a microemulsion with enhanced stability, preventing phase separation, crystallization, and precipitation of active ingredients, thereby extending shelf life across diverse storage conditions.
[0015] The aspects of the present disclosure relate to an herbicidal microemulsion (ME) formulation characterized by nanoscale droplet dimensions, which significantly enhance foliar penetration and translocation of the active ingredient(s). The reduced interfacial tension and increased surface area of the ME system improve bioavailability, thereby enabling superior weed control efficacy at lower application dosages compared to conventional formulations.
[0016] One should appreciate that although the present disclosure has been explained with respect to a defined set of functional modules, any other module or set of modules can be added/deleted/modified/combined and any such changes in architecture/construction of the proposed system are completely within the scope of the present disclosure. Each module can also be fragmented into one or more functional sub-modules, all of which also completely within the scope of the present disclosure.
[0017] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiment's, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiment's of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0019] Figure 1 represents the flow diagram of the ME formulation of Herbicide.
[0020] Figure 2 illustrates HPLC (High-Performance Liquid Chromatography) chromatogram of a mixture containing three active ingredients.
[0021] Figure 3 illustrates HPLC (High-Performance Liquid Chromatography) chromatogram of the ME formulation of the herbicide.
[0022] Figure 4 illustrates the analytical result for the herbicide formulation containing Fomesafen, Clodinafop-Propargyl, and Imazethapyr.

DETAILED DESCRIPTION
[0023] The accompanying table is included to provide a further understanding of the formulation and the methodology, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiment's of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0024] Procedure for Herbicide Formulation
Raw Materials and Quantities
Table 1 presents the raw materials used in the formulation, along with their respective functions and percentages.
Table 1 : ME formulation of Herbicide
Sr. No. Raw Materials Function in formulation %w/w
1 Fomesafen Technical Active Ingredient 17.50
2 Clodinafop-Propargyl Technical Active Ingredient 12.50
3 Imazethapyr Technical Active Ingredient 5.00
4 Castor Oil Ethoxylate Surfactant 20.00
5 Water Solvent 2.00
6 Fatty Acid Amide Mixture Solvent Q.S.
Total 100% w/w
Equipment Required
• Mixing Vessel – SS-304 (with proper agitator)
• Sparker Filter – SS-304
• Packing Unit – Suitable filling and sealing machine
Safety Precautions
• Wear goggles, hand gloves, and helmet during the entire process.
• Ensure proper ventilation in the mixing area.
• Handle all active ingredients carefully to avoid skin or inhalation exposure

Procedure
The procedure for ME formulation of the herbicide is shown in the flow diagram (Figure 1).
Step 1: Preparation
Clean the SS-304 mixing vessel thoroughly to eliminate any residue or contamination from previous batches. Ensure the vessel is completely dry, then check and calibrate the agitator to confirm it is functioning correctly. SS-304 vessels, made from high-grade Stainless Steel 304, are commonly used in the pharmaceutical industry for mixing, storing, and processing liquids, powders, and chemicals. Their non-reactive, corrosion-resistant surfaces help maintain product purity, while the smooth internal finish prevents bacterial growth and allows for easy cleaning and sterilization.
Step 2: Charging of Solvents; Addition of Active Ingredients and Addition of Surfactant
Add the required quantity of Fatty Acid Amide Mixture (solvent) into the mixing vessel (SS-304) and start slow agitation to maintain uniform mixing. Charge Fomesafen Technical (10–50% w/w) slowly into the vessel under continuous stirring, ensuring uniform dispersion. Next, add Clodinafop-Propargyl Technical (5–30% w/w) gradually while maintaining constant agitation to prevent lump formation. Finally, introduce Imazethapyr Technical (1–10% w/w) with continuous stirring, ensuring complete dissolution and homogeneous distribution. Add Castor Oil Ethoxylate (20.00% w/w) into the mixture under stirring and mix until the formulation becomes homogeneous. Then add 2.00% w/w Water into the vessel and continue stirring until uniform.

Step 3: Homogenization (100)
Increase the mixing speed and continue stirring until a uniform and stable formulation is obtained. Check for any undissolved particles or signs of phase separation, and continue mixing if necessary.
Step 4: Filtration (101)
Pass the mixture through the Sparkler Filter (SS-304) to remove insoluble particles and collect the clear filtrate in a clean SS-304 vessel. A sparkler filter, widely used in pharmaceuticals, uses multiple horizontal plates to ensure efficient removal of suspended matter. It provides uniform filtration, easy cleaning, and suitability for sterile operations.
Step 5: Packing
Transfer the filtered formulation into the packing unit and pack it into suitable containers, such as HDPE bottles or drums, as required. Seal, label, and store under the recommended conditions.
[0025] Detailed description of the obtained result
Table 2 provides the details of HPLC (High-Performance Liquid Chromatography) chromatogram of a mixture containing three active ingredients. Experiment is carried out at 220 nm wavelength.
RT Vial Area Area% Height Height%
1.00 2.86 11 3581735.81 14.50 938.79 35.84
2.00 8.59 11 67502.04 0.27 8.32 0.32
3.00 9.29 11 11651348.97 47.18 1093.70 41.75
4.00 15.26 11 9397285.07 38.05 578.94 22.10
Total 24697871.90
In the HPLC chromatogram (Figure 2), the X-axis represents the retention time (RT) in minutes, indicating how long each compound takes to pass through the column, while the Y-axis shows absorbance in milli-absorbance units (mAU) at 220 nm, reflecting the intensity of detection and being proportional to compound concentration. Each distinct peak corresponds to a different compound present in the mixture. In this analysis, four main peaks were observed at approximately 2.86, 8.59, 9.29, and 15.26 minutes, representing the major detected components (Table 2).

Table 3: HPLC (High-Performance Liquid Chromatography) chromatogram data of the ME formulation of the herbicide. Experiment is carried out at 220 nm wavelength
RT Vial Area Area% Height Height%
1.00 2.87 12 3792426.02 12.46 1015.52 31.73
2.00 3.28 12 77730.53 0.26 14.80 0.46
3.00 4.22 12 440906.97 1.45 84.41 2.64
4.00 6.52 12 84438.77 0.28 11.75 0.37
5.00 8.57 12 111432.63 0.37 10.96 0.34
6.00 9.26 12 12108186.26 39.80 1140.29 35.63
7.00 12.17 12 4462256.60 14.67 346.39 10.82
8.00 14.34 12 84683.75 0.28 5.33 0.17
9.00 15.21 12 9262572.87 30.44 570.77 17.84
Total 30424634.39
The HPLC chromatogram of the ME formulation of the herbicide shows three major peaks at 9.26, 12.17, and 15.21 minutes (Figure 3, Table 3), which correspond to the active ingredients. Additional minor peaks represent other formulation components or trace impurities. The peak table confirms their relative proportions, with the three actives contributing the majority of the total area (~85%).
Calculation
The calculation of percentages of three active ingredients in the in the ME formulation of Herbicide is given in Figure 4. The calculation is as follows:
• Weights and purities of standards
• Fomesafen: 0.0613 g, purity 98.05%
• Clodinafop: 0.0458 g, purity 98.85%
• Imazethapyr: 0.0173 g, purity 98.50%
• Weight of sample = 0.3538 g
For each active ingredient, the formula used to calculate the (%, w/w) is:
Content (% w/w) =
(Weight of sample/Weight of standard)× (Area of standard peak/Area of sample peak) × Purity of standard
Fomesafen Calculation
Content = (0.0613/0.3538) x (12108186.26 / 11651348.97) x 98.05 = 17.65% w/w
Clodinafop-Propargyl Calculation
Content = (0.0458/0.3538) x (9262572.87 / 9397285.07) x 98.85 = 12.61% w/w
Imazethapyr Calculation
Content = (0.0173/0.3538) x (3792426.02 / 3581735.81) x 98.50 = 5.10% w/w
Analysis of the ME formulation of Herbicide
The analytical results of the herbicide are presented in Figure 4.
Description
The formulation is required to be a homogeneous and stable liquid, free from any visible sediments or suspended matter. Upon dilution with water, it should form a stable and sprayable emulsion (Figure 4). The sample meets these requirements, as it is uniform and complies with the specified standard.
Cold Test @ 10°C for 1 hour
The requirement is that no turbidity or separation of solid or oily matter should occur when the product is cooled, ensuring stability at lower temperatures. The result complies with this requirement, as the product remains stable.
Flash Point
The requirement specifies that the flash point should be above 24.5°C, which is the minimum temperature at which vapors may ignite (Table 2). This ensures the product is safe for handling and storage. The result complies with this requirement, confirming that the flash point is above 24.5°C and therefore safe.
Emulsion Stability @ 30°C ± 1°C
The requirement is that when 100 ml of emulsion is prepared in standard hard water with 2 ml of EC (Emulsifiable Concentrate), the separation (creaming or sedimentation) must not exceed 2.0 ml. This ensures that the spray solution remains stable. The result complies with this requirement, as the emulsion is stable and within the specified limits.
Water Content (% w/w)
The requirement specifies that the maximum water content should not exceed 2.5%, as excess water can reduce shelf-life or affect stability. The result shows 2.10%, which is within the allowed limit and therefore acceptable.
Fomesafen Content (% w/w)
The requirement is that the content should be 17.5% ± 5%, which corresponds to an acceptable range of 16.63% to 18.38%. The result obtained is 17.65%, which falls within the required range.
Clodinafop-Propargyl Content (% w/w)
The requirement specifies that the content should be 12.5% ± 5%, which gives an acceptable range of 11.88% to 13.13%. The result obtained was 12.61%, which falls within the required range.
Imazethapyr Content (% w/w)
The requirement is 5.0% with a tolerance of +10% and -5%. This gives an acceptable range of 4.75% to 5.50%. The result obtained is 5.10%, which falls within the required range.

Acidity (as H₂SO₄) % w/w
The requirement specifies a maximum acidity of 0.25%, as excessive acidity could lead to instability or corrosion of containers. The result obtained was 0.13%, which is well within the specified limit.
[0026] The present invention presents the following novel features and advantages:
Features:
Multi-Mode of Action (MoA):
Combines Fomesafen (PPO inhibitor), Clodinafop-Propargyl (ACCase inhibitor), and Imazethapyr (ALS inhibitor).
Targets different enzymatic pathways; reduces the risk of weed resistance development.
Broad-Spectrum Weed Control:
Effective against both grasses (Clodinafop-Propargyl) and broadleaf weeds (Fomesafen, Imazethapyr).
Offers season-long control with a single application.
Stable Emulsion Formulation (ME):
Passes emulsion stability, cold test, and description requirements.
Ensures good miscibility in hard water and uniform spray quality.
Safe Physical-Chemical Profile:
Flash point above 24.5 °C; safer handling and storage.
Low water content (2.10% within 2.5% max) and low acidity (0.13% vs 0.25% max); minimizes container corrosion and product degradation.
Optimized Active Ingredient Ratios:
Carefully balanced actives (Fomesafen (10–50% % w/w), Clodinafop-propargyl (5–30% w/w), and Imazethapyr (1–10% w/w) within tolerance limits; ensures consistent efficacy in the field.
Advantages Over Conventional Herbicides
Resistance Management:
Commercial products with single MoA often face resistance problems.
This combination delays resistance due to its multi-target action.
Reduced Number of Applications:
Farmers may use one product instead of tank-mixing multiple herbicides.
Saves cost, time, and labor.
Improved Spray Stability:
Standard hard-water test passed; ensures uniform spray, avoids clogging of nozzles.
Environmental & Crop Safety:
Lower acidity reduces soil and container corrosion.
Stable formulation prevents phase separation or sedimentation.
Cost-Effectiveness:
• A single formulation replaces multiple herbicides.
• Reduces procurement and storage costs for farmers.
In summary, this herbicide is a novel multi-active, broad-spectrum, and stable emulsion formulation that combines the strengths of three herbicides into one product. It offers superior weed control, resistance management, and ease of use compared to conventional single-active herbicides.
[0027] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
, Claims:We Claim:
1. A herbicidal microemulsion (ME) formulation (101) with a combination of three active ingredients and a tailored surfactant–co-solvent system configured to enhance stability and biological efficacy comprising:
a) Fomesafen (10–50% w/w), functioning as a protoporphyrinogen oxidase (PPO) inhibitor for broad-spectrum post-emergence weed control.
b) Clodinafop-propargyl (5–30% w/w), an aryloxyphenoxypropionate herbicide that selectively targets grass weeds by inhibiting acetyl-CoA carboxylase (ACCase).
c) Imazethapyr (1–10% w/w), an imidazolinone herbicide that acts on broadleaf and grassy weeds through inhibition of acetohydroxyacid synthase (AHAS/ALS).
d) Castor oil ethoxylate (20% w/w), serving as a non-ionic surfactant to facilitate microemulsion formation, improve solubilization of hydrophobic actives, and aid in leaf surface spreading.
e) A fatty acid amide mixture functioning as a co-solvent system, providing compatibility among the active ingredients, enhancing emulsification, and improving formulation robustness.
f) Water as the continuous phase, forming the external medium of the microemulsion.
This balanced microemulsion enables simultaneous delivery of three herbicides, providing synergistic activity, enhanced efficacy, reduced resistance risk, and superior field performance.

2. The formulation of claim 1, wherein the synergistic interaction of Fomesafen (PPO inhibitor), Clodinafop-Propargyl (ACCase inhibitor), and Imazethapyr (ALS inhibitor) provides multi-mode of action, thereby reducing the likelihood of resistance development in weed populations.
3. The formulation of claim 1, wherein the active ingredients collectively provide enhanced and broad-spectrum weed control, including efficacy against a wide range of monocotyledonous and dicotyledonous weed species across different growth stages and environmental conditions.
4. The formulation of claim 1, characterized by enhanced emulsion stability, wherein when 100 ml of the emulsion is prepared in standard hard water with 2.0 ml of emulsifiable concentrate, the total phase separation, including creaming at the top and sedimentation at the bottom, does not exceed 2.0 ml.
5. The formulation of claim 1, wherein the physicochemical profile comprises:
• Flash point above 24.5 °C,
• Water content not exceeding 2.5% w/w, and
• Acidity (as H₂SO₄) not exceeding 0.25% w/w,
these parameters collectively conferring enhanced safety during handling, improved storage stability, and reduced risk of container corrosion.
6. The formulation of claim 1, wherein the use of Castor oil Ethoxylate as a non-ionic surfactant enhances miscibility in hard water, improves sprayability, and ensures uniform droplet distribution during field application.
7. The formulation of claim 1, wherein the application of the formulation reduces the number of required herbicide sprays compared to conventional single-active herbicides, thereby lowering input cost, labor, and environmental load.
8. The formulation of claim 1, wherein the stable emulsion system enables long-term storage stability, preventing phase separation, sedimentation, or degradation of active ingredients under standard storage conditions.