CN107306942B

CN107306942B - Preparation method of controlled release type nano pesticide preparation

Info

Publication number: CN107306942B
Application number: CN201710486028.4A
Authority: CN
Inventors: 崔海信; 王琰; 王安琪
Original assignee: Institute of Environment and Sustainable Development in Agriculturem of CAAS
Current assignee: Institute of Environment and Sustainable Development in Agriculturem of CAAS
Priority date: 2017-06-23
Filing date: 2017-06-23
Publication date: 2021-03-19
Anticipated expiration: 2037-06-23
Also published as: CN107306942A

Abstract

The invention provides a preparation method of a nano pesticide preparation, which comprises the following steps: emulsifying the components of the nano pesticide preparation to form a primary emulsion, and then homogenizing under high pressure to form a miniemulsion to prepare the wall material-wrapped nano pesticide preparation. The preparation method of the nano pesticide preparation provided by the invention is simple, easy to operate and good in repeatability, and the prepared nano pesticide preparation is small in particle size, good in particle dispersibility and excellent in slow release performance.

Description

Preparation method of controlled release type nano pesticide preparation

Technical Field

The invention belongs to the technical field of pesticides. In particular to a preparation method of a nano pesticide preparation.

Background

The pesticide is an important material basis for guaranteeing national food safety. Most of traditional pesticide formulations are open systems, from the registration condition of the pesticide formulations, traditional pesticide formulations mainly comprising missible oil, wettable powder, microemulsion and the like account for over 70 percent of the domestic market, most of the traditional pesticide formulations belong to open systems, losses such as dropping, drifting, bouncing, dust drifting and the like exist to different degrees in the using process, the effective utilization rate of the final target of the crop is less than 30 percent, the amount of the pesticide applied to the body of the pest is less than 0.1 percent, and the effective utilization rate of the pesticide is lower.

When the pesticide is prepared into dosage forms with different structures such as spherical and hollow capsule shapes by adopting a high polymer material for wrapping, coupling and inlaying, the wall material can provide a physical barrier effect, so that ultraviolet light can be shielded, the illumination stability of the pesticide is obviously improved, the adsorption of soil is reduced, the degradation, decomposition and loss caused by illumination or other adverse factors are delayed, the toxicity can be reduced, the pollution is reduced, and the prevention and treatment effect of the product is improved. The preparation also has the function of controlling release, and can be divided into a slow release type and a quick release type according to different application scenes. The slow release type is mainly used for soil treatment and seed treatment, while the fast release type is mainly used for stem leaf spraying, ground sealing treatment and airplane control. However, from the registration of the existing pesticide dosage forms, the dosage forms such as spherical pesticide forms and capsule forms account for a smaller proportion of the pesticide compared with other dosage forms, and the development process is relatively complex.

The traditional preparation method of the pesticide microsphere/microcapsule preparation mainly comprises an in-situ polymerization method, an interface polymerization method, a condensation method, a spray drying method and the like. The in-situ polymerization method needs to be heated for a certain time when the capsule wall is formed, so that not only is certain requirement on process equipment required, but also the repeatability of the product is influenced. When the high-concentration microsphere/microcapsule preparation is prepared by adopting an interfacial polymerization method, the crystallization phenomenon is easy to occur, and the crystallized irregular crystals can damage the capsule wall, so that the drug effect cannot be exerted. The spray drying method is a physical preparation method, and the pesticide microsphere/microcapsule preparation prepared by the method has larger grain diameter, and the grain diameter is difficult to realize nano-scale. The pesticide microsphere/microcapsule preparation prepared by the traditional method at present has the following defects: in terms of structure, the particle size of the current commercially available pesticide microsphere/microcapsule preparation is generally about 5 microns, and does not reach the nanometer level, and the large particle size easily causes drop rolling and dust drift, so that the adhesion, permeability and bioavailability to a crop target are poor in the using process, and the activity is low; in the aspect of particle dispersibility, the currently prepared pesticide microsphere/microcapsule preparation has poor monodispersity, serious agglomeration and uneven particle size distribution, and the surface property and the structural morphology of the pesticide microsphere/microcapsule preparation are not effectively regulated and controlled; in the aspect of controllable slow release of pesticide, most of the existing pesticide microsphere/microcapsule preparations can only realize simple and qualitative slow release, and the release rate is unstable and controllable; in the aspect of process flow, the traditional method mostly adopts the processes of heating, heat preservation, gas protection and the like, and has complex process, difficult control and poor repeatability.

Therefore, how to provide a preparation method of pesticide microsphere/microcapsule preparation with simple process, easy operation and good repeatability, so that the preparation of nano pesticide preparation with small particle size, good particle dispersibility and excellent slow release performance becomes a problem to be solved in the field.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a method for preparing a nano pesticide preparation, which is simple, easy to operate, and has good repeatability, and the prepared nano pesticide preparation has a small particle size, good particle dispersibility, and excellent sustained release properties.

In order to achieve the above object, the present invention provides a method for preparing a nano pesticide formulation, the method comprising: the components of the nano pesticide preparation are emulsified to form primary emulsion, and then the primary emulsion is homogenized under high pressure to form fine emulsion, so that the nano pesticide preparation is prepared.

In some embodiments, the method of making comprises the steps of:

step a: mixing the pesticide active ingredient, the organic solvent, the capsule wall material, the emulsifying dispersant and water, and then emulsifying to obtain a primary emulsion;

step b: b, carrying out fine emulsification on the primary emulsion obtained in the step a through high-pressure homogenization to obtain a fine emulsion;

step c: b, stirring the miniemulsion obtained in the step b to volatilize the organic solvent to obtain a nano pesticide mother solution;

step d: and c, mixing the nano pesticide mother liquor obtained in the step c with an excipient and an auxiliary agent to obtain the nano pesticide preparation.

In some embodiments, the nano-pesticide formulation is spherical, and the step a comprises: dissolving pesticide active ingredients in an organic solvent, adding a capsule wall material to obtain an oil phase, dissolving an emulsifying dispersant in water to obtain a water phase, mixing the oil phase and the water phase, and emulsifying to obtain an O/W (oil-in-water) type primary emulsion.

In some embodiments, the nano-pesticide formulation is a nano-pesticide aqueous suspension, the excipient is a thickener, and step d comprises: and d, directly adding a thickening agent and an auxiliary agent into the nano pesticide mother liquor obtained in the step c, and uniformly mixing to obtain the nano pesticide water suspending agent.

In some embodiments, the nano-pesticide formulation is a nano-pesticide solid powder, the excipient is a solid filler, and step d comprises: and c, centrifuging and drying the nano pesticide mother liquor obtained in the step c to obtain solid powder, adding a solid filler and an auxiliary agent, and uniformly mixing to obtain the nano pesticide solid powder.

In some embodiments, the emulsification in step a is one or more of ultrasonic emulsification, shear emulsification and grinding emulsification, preferably one or more of shear emulsification and grinding emulsification; the particle size of the droplets of the primary emulsion is 100-900nm, preferably 100-500 nm.

Wherein the ultrasonic emulsification is carried out by an ultrasonic crusher, and the power of the ultrasonic crusher is 65-650W, preferably 325-637W, more preferably 585W; the time of ultrasonic emulsification is 2-30min, preferably 5-25min, more preferably 15 min.

Wherein the shearing emulsification is carried out by adopting a high-speed shearing machine, and the shearing rotating speed of the high-speed shearing machine is 10000-28000rmp, preferably 22000-28000rmp, and more preferably 28000 rmp; the shearing time is 3-40min, preferably 3-30min, more preferably 15 min.

Wherein the grinding emulsification is carried out by a grinding dispersion machine, and the frequency of the grinding emulsification is 30-50Hz, preferably 40-50Hz, and more preferably 50 Hz; the milling time is 5-60min, preferably 5-40min, more preferably 15 min.

In some embodiments, the high-pressure homogenization in step b is performed by using a high-pressure homogenizer, and the pressure for the high-pressure homogenization is 100-1200Pa, preferably 600-1000Pa, and more preferably 900 Pa; the high pressure homogenizing time is 10min-2h, preferably 10min-1h, more preferably 15 min; the droplets of the miniemulsion have a particle size of 10 to 600nm, preferably 10 to 100 nm.

In some embodiments, the step c is performed by stirring with an electric stirrer, wherein the stirring speed is 500-; the stirring time is 5-24h, preferably 10-20h, more preferably 12 h.

In some embodiments, when the nano pesticide preparation is a nano pesticide solid powder, in the step d, a high-speed refrigerated centrifuge is adopted to centrifuge at the rotation speed of 4000-15000rpm for 10-30 min; preferably, a high-speed refrigerated centrifuge is adopted for centrifuging for 20-30min at the rotating speed of 4000-; more preferably, a high speed refrigerated centrifuge is used for centrifugation at 15000rpm for 20 min.

In some embodiments, when the nano pesticide preparation is a nano pesticide solid powder, the drying in the step d is spray drying or freeze drying, wherein the spray drying is performed by using a spray dryer, and the conditions of the spray drying are that the inlet air temperature is 30-300 ℃, the outlet air temperature is 30-140 ℃, and the drying time is 1-1.5 s; the freeze drying is carried out by adopting a freeze dryer, and the condition of freeze drying is pre-freezing for 4h at-50 ℃ and keeping for 12-24h at-60 ℃; preferably pre-frozen at-50 ℃ for 4h and maintained at-60 ℃ for 12 h.

In some embodiments, the particle size of the nanoparticie formulation is from 20 to 500nm, preferably less than or equal to 100nm, more preferably less than 50 nm; preferably, the drug-loading rate of the nano pesticide solid powder is 0.1-90%, and the drug-loading rate of the nano pesticide water suspending agent is 0.1-20%.

In some embodiments, the nano-pesticide formulation is made from, by weight:

active ingredients of the pesticide: 0.1 to 40 portions

Capsule wall material: 0.1 to 40 portions

Emulsifying and dispersing agent: 0.2 to 30 portions of

Organic solvent: 10-300 parts

Water: 20-500 parts of

Excipient: 0.1 to 400 portions

Auxiliary agents: 0 to 20 portions of the components are added,

wherein the ratio of the pesticide active ingredient to the capsule wall material is 0.1:1-10: 1.

In some embodiments, the nano-pesticide formulation is a nano-pesticide solid powder, wherein the excipient is a solid filler, and the nano-pesticide solid powder is prepared from the following components by weight:

active ingredients of the pesticide: 0.1 to 40 portions

Capsule wall material: 0.1 to 40 portions

Emulsifying and dispersing agent: 0.2 to 30 portions of

Organic solvent: 10-300 parts

Water: 20-500 parts of

Solid filler: 0.1 to 400 portions

Auxiliary agents: 0 to 20 portions of the components are added,

wherein the ratio of the pesticide active ingredient to the capsule wall material is 0.1:1-10: 1;

preferably, the nano pesticide solid powder is prepared from the following components in parts by weight:

active ingredients of the pesticide: 0.5 to 30 portions of

Capsule wall material: 0.5 to 30 portions of

Emulsifying and dispersing agent: 0.5 to 20 portions of

Organic solvent: 10 to 100 portions of

Water: 50-200 parts of

Solid filler: 10-400 parts of

Auxiliary agents: 0-15 parts;

more preferably, the nano pesticide solid powder is prepared from the following components in parts by weight:

active ingredients of the pesticide: 1-20 parts of

Capsule wall material: 1-20 parts of

Emulsifying and dispersing agent: 0.5 to 10 portions of

Organic solvent: 20-100 parts of

Water: 50-200 parts of

Solid filler: 10-200 parts of

Auxiliary agents: 0-15 parts.

Or the nano pesticide preparation is a nano pesticide water suspending agent, wherein the excipient is a thickening agent, and the nano pesticide water suspending agent is prepared from the following components in parts by weight:

active ingredients of the pesticide: 0.1 to 40 portions

Capsule wall material: 0.1 to 40 portions

Emulsifying and dispersing agent: 0.2 to 30 portions of

Organic solvent: 10-300 parts

Water: 20-500 parts of

Thickening agent: 0.1 to 20 portions

Auxiliary agents: 0 to 20 portions of the components are added,

preferably, the nano pesticide aqueous suspension is prepared from the following components in percentage by weight:

active ingredients of the pesticide: 0.5 to 30 portions of

Capsule wall material: 0.5 to 30 portions of

Emulsifying and dispersing agent: 0.5 to 20 portions of

Organic solvent: 10 to 100 portions of

Water: 50-200 parts of

Thickening agent: 1-15 parts of

Auxiliary agents: 0-15 parts;

more preferably, the nano pesticide aqueous suspension is prepared from the following components in percentage by weight:

active ingredients of the pesticide: 1-20 parts of

Capsule wall material: 1-20 parts of

Emulsifying and dispersing agent: 0.5 to 10 portions of

Organic solvent: 20-100 parts of

Water: 50-200 parts of

Thickening agent: 1-10 parts of

Auxiliary agents: 0-15 parts.

In some embodiments, the pesticidal active ingredient is selected from one or more of an insecticide, a fungicide, a herbicide, and a plant growth regulator;

the capsule wall material is degradable high polymer material.

In some embodiments, the pesticide is selected from one or more of the following: abamectin, emamectin benzoate, lambda-cyhalothrin, chlorantraniliprole, spinosad, indoxacarb, clothianidin, carbosulfan, triazophos, diosmetin, acarbox, chlorpyrifos, bifenthrin, cyphenothrin, ethofenprox, deltamethrin, fenvalerate, frapperin, tefluthrin, fosthiazate, phoxim, imidacloprid and thiamethoxam, preferably one or more of thiamethoxam, spinosad, chlorantraniliprole, abamectin, emamectin benzoate and lambda-cyhalothrin.

In some embodiments, the antimicrobial agent is selected from one or more of the following: azoxystrobin, pyraclostrobin, thifluzamide, metconazole, cyazoxystrobin, fluazinam, cymoxanil, boscalid, ethofenprox, cyflumetofen, fenpropathrin, benzothiostrobin, pefurazoate, prochloraz, propiconazole, difenoconazole, mefenoxam, flusilazole, epoxiconazole, trifloxystrobin and pyraclostrobin, preferably one or more of thifluzamide, metconazole, cyenophostrobin, fluazinam, azoxystrobin, pyraclostrobin, cymoxanil and boscalid.

In some embodiments, the herbicide is selected from one or more of the following: pendimethalin, triallate, 2,4-D isooctyl ester, prosulfocarb, cycloxaben, galbanum, clomazone, butralin, metolachlor, trifluralin and prometryn, preferably one or more of pendimethalin and metolachlor.

In some embodiments, the plant growth regulator is selected from one or more of the following: brassinolide, aminoxyethylvinylglycine and a paclobutrazol plant growth regulator, preferably the paclobutrazol plant growth regulator.

In some embodiments, the wall material is selected from one or more of the following: polyester acrylate and its derivatives, polyvinyl acetate resin, polyacrylonitrile resin, polystyrene resin, polylactic acid, gelatin, modified starch, cellulose and its derivatives, chitosan and acacia, preferably one or more of cellulose and its derivatives, chitosan, polylactic acid and modified starch.

In some embodiments, the emulsifying dispersant is one or more of an agricultural emulsifier and a dispersant, preferably, the agricultural emulsifier is selected from one or more of OP series (octylphenol polyoxyethylene ether, such as OP-10), NP series (nonylphenol polyoxyethylene ether), EL series (castor oil polyoxyethylene ether, such as EL 40), Tween series (tweens, such as Tween 80, Tween 60, Tween 20), Span series (Span, such as Span 60, Span 80), AEO series (fatty alcohol polyoxyethylene ether, such as AEO-9), agricultural milk series, polyvinyl alcohol, polyethylene glycol fatty acid esters, polyvinylpyrrolidone, and polyethylene glycol oleate; preferably one or more of Tween series, polyvinyl alcohol and emulsifier of agricultural milk series; more preferably one or more emulsifiers selected from the group consisting of polyvinyl alcohol, Nongru 300 series, Nongru 500 series, Nongru 600 series, Nongru 700 series, and Nongru 1600 series (e.g. Nongru 1601).

In some embodiments, the dispersant is selected from one or more of carboxylate, sulfate, sulfonate, phosphate ester salt, and alkylphenol ethoxylates, preferably, the dispersant is selected from one or more of fatty alcohol-polyoxyethylene ether carboxylate, sodium lauryl sulfate, lignosulfonate, sodium dodecylsulfonate, maleated rosin polyoxyethylene-oxypropylene ether sulfonate, and dodecyl ether phosphate salt, more preferably one or more of lignosulfonate, sodium dodecylsulfate, and sodium dodecylsulfate.

In some embodiments, the adjuvant is selected from one or more of a preservative, a defoamer, an antifreeze, a pH adjuster, and a wetting dispersant, preferably one or more of an antifreeze, a defoamer, and a wetting dispersant (e.g., TERSPERSE 2020).

In some embodiments, the antifreeze agent is selected from one or more of ethylene glycol, propylene glycol, glycerol, isopropanol, and urea, preferably ethylene glycol.

In some embodiments, the defoamer is selected from one or more of silicone based and lower alcohol defoamers, preferably silicone based defoamers.

In some embodiments, the thickening agent is selected from one or more of xanthan gum, gum arabic, gelatin, cellulose and its derivatives, diatomaceous earth, polyvinyl alcohol, sodium polyacrylate, dextrin, magnesium aluminum silicate, and silica gel, preferably one or more of xanthan gum, gelatin, magnesium aluminum silicate, cellulose and its derivatives, and polyvinyl alcohol.

In some embodiments, the organic solvent is selected from one or more of dichloromethane, chloroform, vegetable oils, petroleum ethers, and aliphatic hydrocarbon solvent oils, preferably dichloromethane.

In some embodiments, the solid filler is selected from one or more of diatomaceous earth, kaolin, talc, montmorillonite, silica, corn starch, and sepiolite, preferably one or more of kaolin, corn starch, and silica.

By adopting the method of the invention, the nano-scale spherical pesticide preparation can be obtained, and the nano-scale pesticide preparation provides a new way for improving the effective utilization rate of the pesticide due to the small size, the large specific surface area and the modifiability. The unique surface effect and small-size effect of the nano carrier material are utilized, the medicine is loaded in the modes of adsorption, coupling, wrapping or embedding, the efficient loading of the medicine can be realized, the intelligent and accurate release of the medicine in time, space and dosage can be realized by adjusting the fine structure of the nano carrier, the minimum effective target action concentration is maintained in a set period, and the effectiveness and the safety of the medicine are greatly improved. By the functions of carrier loading, water-based dispersion, targeted transmission, controllable release and the like of the nano drug-carrying system, the dispersibility, stability and utilization rate of the pesticide can be improved, the lasting period is prolonged, and the residual pollution is reduced. In addition, compared with a micron-scale microsphere/microcapsule formulation, the granularity of the nano pesticide preparation reaches the nano level, the small-size effect of the nano pesticide preparation can increase the ductility, wettability and target adsorbability of pesticide droplets in the field spraying process, the nano pesticide preparation has the advantages of higher efficiency and environmental protection, the nano pesticide preparation is easier to deposit on plant leaves, the characteristic of large specific surface area of the nano pesticide preparation increases the adhesion to the target, and the loss of pesticide is reduced.

The high-pressure homogenization method is that liquid materials flow through a special homogenization cavity at high speed under the action of ultrahigh pressure to generate fine liquid drops. The high-pressure homogenization method can produce micro/nano-scale particles, and effectively prevent the particles from caking. The invention adopts a new preparation process to prepare the nano pesticide preparation, and particularly adopts a homogeneous emulsification method to prepare the nano pesticide preparation. In the preparation method, firstly one or more of ultrasonic emulsification, shearing emulsification and grinding emulsification are adopted to prepare primary emulsion, then a miniemulsion is prepared by adopting a high-pressure homogenization method, and finally an excipient and an auxiliary agent are added to obtain the nano pesticide preparation with good dispersibility.

The invention adopts a homogeneous emulsification method to prepare the nano pesticide preparation, and prepares the nano pesticide preparation with uniform dispersion and excellent performance by adjusting the component formula, the process flow, parameters in the steps and the like.

Compared with the prior art, the preparation method of the nano pesticide preparation provided by the invention has the following advantages:

1. in terms of particle size, the nano pesticide preparation has a nano particle size which can be smaller than 50nm, so that the specific surface area of the nano pesticide preparation is increased, the contact area of the pesticide and the surface of crops is increased, the adhesion and the permeability of the pesticide on the leaf surfaces of the crops are increased, the pesticide is favorably embedded into a micro-nano structure of the leaf surfaces of the crops, the retention rate of the leaf surfaces is enhanced, the loss is reduced, the effective utilization rate and the pesticide effect of the pesticide are improved, and the amount and the frequency of pesticide spraying are reduced; in addition, the nano pesticide preparation has smaller particle size, increases the contact area with the pest target, and can increase the insecticidal activity to the pest target;

2. in terms of particle size, the nano pesticide preparation prepared by the method has a nano-scale particle size which can be smaller than 50nm, so that the specific surface area of the nano pesticide preparation is increased, the contact area of the pesticide and the surface of crops is increased, the adhesion and permeability of the pesticide on the leaf surfaces of the crops are increased, the retention rate of the leaf surfaces is enhanced, the nano pesticide preparation is favorably embedded into a micro-nano structure of the leaf surfaces of the crops, loss is reduced, and the effective utilization rate and the pesticide effect of the pesticide are improved; in addition, the nano pesticide preparation prepared by the method has smaller particle size, increases the contact area with the pest target and can increase the insecticidal activity to the pest target;

3. in the aspect of particle dispersibility, the nano pesticide preparation prepared by the method has good monodispersity, small particle size and uniform distribution;

4. in the aspect of controllable slow release of pesticide, the slow release speed of the nano pesticide preparation prepared by the method is accurate and adjustable, and the accurate regulation and control of the slow release speed of the pesticide can be realized by adjusting one or more of the component content, the particle size, the morphology structure, the porous structure, the total pore volume, the pore canal number and the like; the regulation and control period of the slow-release pesticide preparation prepared by the traditional method is limited at present, but the slow-release period of the nano pesticide preparation prepared by the method can be regulated and controlled within 3 days to 3 months according to the specific application scene requirements, so that the slow-release period of the pesticide preparation is effectively prolonged, the activity of the pesticide is improved, and the spraying times and dosage are reduced;

5. in the aspect of materials, the wall material of the nano pesticide preparation prepared by the method is made of safe, low-cost and degradable high polymer materials, so that the pollution to the environment is reduced;

6. in the aspect of drug loading, the drug loading of the nano pesticide preparation prepared by the method can be adjusted between 0.1 and 90 percent, and the application range is wider;

7. in the aspect of ultraviolet light degradation resistance, the method can effectively improve the ultraviolet light degradation resistance of the nano pesticide preparation, thereby greatly improving the effective utilization rate and bioavailability, reducing the application frequency and dosage and being beneficial to environmental protection and ecological safety.

Drawings

FIG. 1 is a transmission electron microscope picture and a particle size distribution diagram of a lambda-cyhalothrin nano pesticide preparation prepared by an embodiment of the invention;

FIG. 2 is a scanning electron microscope picture of the avermectin nano-pesticide preparation prepared by the embodiment of the invention;

fig. 3 is a scanning electron microscope picture of the emamectin benzoate nano-pesticide preparation prepared in the embodiment of the invention;

fig. 4 is an electron microscope picture of the avermectin nano-pesticide preparation prepared by the embodiment of the invention;

fig. 5 is a particle size and a particle size distribution diagram of the avermectin nano-pesticide preparation prepared by the embodiment of the invention;

fig. 6 shows the distribution of the emamectin benzoate nano-pesticide preparation prepared by the embodiment of the invention on cucumber leaves;

FIG. 7 is a slow release curve of the nano pesticide preparation of avermectin prepared by the embodiment of the invention;

fig. 8 is an ultraviolet photolysis graph of the avermectin nano-pesticide preparation prepared by the embodiment of the invention.

Detailed Description

The invention is illustrated below with reference to specific examples. It will be understood by those skilled in the art that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention in any way.

The experimental procedures in the following examples are conventional unless otherwise specified. The raw materials and materials of the reagents used in the following examples are all commercially available products unless otherwise specified.

Instrument for measuring the position of a moving object

Ultrasonic grinder (SCIENTZ, JY92-IIN)

High speed shearer (FLUKO, FA25)

Grinding disperser (SGN, GMSD2000/4)

High pressure homogenizer (ATS, AH-100D)

Electric blender (IKA, EUROSTAR 60)

High speed refrigerated centrifuge (Thermo SCIENTIFIC, ST 16R)

Freeze dryer (BIOCOOL, Pilot2-4M)

Scanning electron microscope (Hitachi, SU8010)

Transmission electron microscope (HITACHI HT7700)

Environment scanning electron microscope (FEI, Quanta FEG 250)

Nanometer laser particle size analyzer (Malvern, Nano ZS90)

Ultraviolet visible spectrophotometer (Shimadzu, TU901)

Pesticide light stability test box (Xutemp, XT5409-XPC80)

EXAMPLE 1 preparation of solid Nano-pesticide powder 1

Dissolving 2g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material cellulose to obtain an oil phase, dissolving 2g of emulsifying dispersant (1g of polyvinyl alcohol and 1g of agricultural emulsion 1601) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and ultrasonically emulsifying for 15min at 585W by using an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 600 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 400 nm.

And stirring the miniemulsion for 24 hours at 1500rpm by using an electric stirrer to volatilize the organic solvent to obtain the nano pesticide mother liquor.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 1.

EXAMPLE 2 preparation of Nanospermatism aqueous suspension 2

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 2.

EXAMPLE 3 preparation of solid Nano-pesticide powder 3

Dissolving 2g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 1g of emulsifying dispersant (0.5g of polyvinyl alcohol and 0.5g of agricultural emulsion 1601) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 15min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 300 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 100 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 3.

EXAMPLE 4 preparation of Nanospermatism aqueous suspension 4

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 4.

EXAMPLE 5 preparation of solid pesticide nanopowder 5

Dissolving 4g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 2g of emulsifying dispersant (1g of polyvinyl alcohol and 1g of agricultural emulsion 1601) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 15min at 50Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 250 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 90 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 12h at-60 ℃ to obtain solid powder, adding 100g of solid filler kaolin and 1g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 5.

EXAMPLE 6 preparation of Nanospermatism aqueous suspension 6

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 6.

Example 7 preparation of solid pesticide nanopowder 7

Dissolving 2g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 3g of emulsifying dispersant (2g of polyvinyl alcohol and 1g of gelatin) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 15min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 300 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 7.

EXAMPLE 8 preparation of solid pesticide nanopowder 8

Dissolving 2g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 2.5g of emulsifying dispersant (1.5g of polyvinyl alcohol and 1g of gelatin) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 15min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 500 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 8.

EXAMPLE 9 preparation of solid pesticide nanopowder 9

Dissolving 2g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 2g of emulsifying dispersant (1g of polyvinyl alcohol and 1g of gelatin) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 15min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 650 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 600 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 9.

EXAMPLE 10 preparation of solid pesticide nanopowder 10

Dissolving 2g of pesticide active ingredient abamectin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 1.5g of emulsifying dispersant (0.5g of polyvinyl alcohol and 1g of gelatin) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 15min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 900 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 800 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 12h at-60 ℃ to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 10.

EXAMPLE 11 preparation of solid Nano-pesticide powder 11

Dissolving 2g of pesticide active ingredient emamectin benzoate in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material cellulose to obtain an oil phase, dissolving 2.5g of emulsifying dispersant (1g of polyvinyl alcohol and 1.5g of EL 40) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification for 15min at 585W by using an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 100g of solid filler kaolin and 0.5g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 11.

EXAMPLE 12 preparation of Nanospermatism aqueous suspension 12

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 12.

EXAMPLE 13 preparation of solid Nano-pesticide powder 13

Dissolving 2g of pesticide active ingredient emamectin benzoate in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material cellulose to obtain an oil phase, dissolving 0.5g of emulsifying dispersant polyvinyl alcohol in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 15min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 600 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 12h at-60 ℃ to obtain solid powder, adding 80g of solid filler kaolin and 0.3g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 13.

EXAMPLE 14 preparation of Nanospermatism aqueous suspension 14

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 14.

EXAMPLE 15 preparation of solid pesticide nanopowder 15

Dissolving 2g of pesticide active ingredient emamectin benzoate in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material cellulose to obtain an oil phase, dissolving 2.5g of emulsifying dispersant (1g of polyvinyl alcohol and 1.5g of EL 40) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 15min at 50Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 250 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 12h at-60 ℃ to obtain solid powder, adding 80g of solid filler kaolin and 0.5g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 15.

EXAMPLE 16 preparation of Nanospermatism aqueous suspension 16

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 16.

EXAMPLE 17 preparation of solid pesticide nanopowder 17

Dissolving 2g of pesticide active ingredient efficient cyhalothrin in 100ml of organic solvent dichloromethane, adding 2g of wall material polylactic acid to obtain an oil phase, dissolving 6g of emulsification dispersant sodium dodecyl sulfate in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 6min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 150 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 15min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 50 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 12h at-60 ℃ to obtain solid powder, adding 150g of solid filler kaolin and 0.2g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 17.

EXAMPLE 18 preparation of Nanospermatism aqueous suspension 18

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 18.

EXAMPLE 19 preparation of solid pesticide nanopowder 19

Dissolving 2g of pesticide active ingredient lambda-cyhalothrin in 50ml of organic solvent dichloromethane, adding 2g of capsule wall material polylactic acid to obtain an oil phase, dissolving 3g of emulsifying dispersant polyvinyl alcohol in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification for 15min at 585W by using an ultrasonic crusher to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 200 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 70 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 120g of solid filler kaolin and 0.2g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 19.

EXAMPLE 20 preparation of Nanospermatism aqueous suspension 20

Adding 2g of thickening agent (1g of xanthan gum and 1g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 20.

EXAMPLE 21 preparation of solid pesticide nanopowder 21

Dissolving 4g of pesticide active ingredient lambda-cyhalothrin in 50ml of organic solvent dichloromethane, adding 2g of wall material polylactic acid to obtain an oil phase, dissolving 4g of emulsifying dispersant (2g of EL 40 and 2g of agricultural emulsion 500) in 200ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 15min at 50Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 200 nm.

Homogenizing the O/W type primary emulsion at 900Pa for 10min by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 40 nm.

Centrifuging the nanometer pesticide mother liquor for 20min at 10000rpm by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping the temperature at-60 ℃ for 12h to obtain solid powder, adding 200g of solid filler kaolin and 1g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nanometer pesticide solid powder 21.

EXAMPLE 22 preparation of Nanospermatism aqueous suspension 22

Adding 1g of thickening agent (0.5g of xanthan gum and 0.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 22.

EXAMPLE 23 preparation of solid pesticide nanopowder 23

Dissolving 0.1g of pesticide active ingredient abamectin in 10ml of organic solvent dichloromethane, adding 1g of capsule wall material polylactic acid to obtain an oil phase, dissolving 0.2g of emulsifying dispersant (0.1g of polyvinyl alcohol and 0.1g of lignosulfonate) in 20ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification at 65W for 30min by using an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 300 nm.

Homogenizing the O/W type primary emulsion for 2h at 1200Pa by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 50 nm.

And stirring the miniemulsion for 20 hours at 1300rpm by using an electric stirrer to volatilize the organic solvent to obtain the nano pesticide mother liquor.

And (2) centrifuging the nano pesticide mother liquor for 30min at 4000rpm by using a high-speed refrigerated centrifuge, then performing spray drying for 1s at the air inlet temperature of 100 ℃ and the air outlet temperature of 140 ℃ by using a spray dryer to obtain solid powder, adding 0.1g of solid filler diatomite, and uniformly mixing to obtain the nano pesticide solid powder 23.

EXAMPLE 24 preparation of Nanospermatism aqueous suspension 24

Dissolving 0.1g of pesticide active ingredient abamectin in 10ml of organic solvent dichloromethane, adding 1g of capsule wall material polylactic acid to obtain an oil phase, dissolving 0.2g of emulsifying dispersant (0.1g of polyvinyl alcohol and 0.1g of lignosulfonate) in 20ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification at 325W for 15min by adopting an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 300 nm.

Homogenizing the O/W type primary emulsion for 1h under 1000Pa by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 50 nm.

And stirring the miniemulsion for 22 hours at 1000rpm by using an electric stirrer to volatilize the organic solvent to obtain the nano pesticide mother liquor.

0.1g of thickening agent xanthan gum is added into the nano pesticide mother liquor and uniformly mixed to obtain the nano pesticide water suspending agent 24.

EXAMPLE 25 preparation of solid pesticide nanopowder 25

Dissolving 1g of pesticide active ingredient emamectin benzoate in 10ml of organic solvent dichloromethane, adding 0.1g of capsule wall material polylactic acid to obtain an oil phase, dissolving 0.2g of emulsifying dispersant (0.1g of polyvinyl alcohol and 0.1g of lignosulfonate) in 20ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification at 585W for 5min by using an ultrasonic crusher to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 500 nm.

Homogenizing the O/W type primary emulsion at 600Pa for 50min to obtain fine emulsion with droplet size of 50 nm.

And stirring the miniemulsion for 5 hours at 1500rpm by using an electric stirrer to volatilize the organic solvent to obtain the nano pesticide mother liquor.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then performing spray drying for 1.2s at the air inlet temperature of 300 ℃ and the air outlet temperature of 100 ℃ by using a spray dryer to obtain solid powder, adding 0.1g of solid filler diatomite and 0.05g of auxiliary agent propylene glycol, and uniformly mixing to obtain the nano pesticide solid powder 25.

EXAMPLE 26 preparation of Nanospermatism aqueous suspension 26

Dissolving 1g of pesticide active ingredient emamectin benzoate in 10ml of organic solvent dichloromethane, adding 0.1g of capsule wall material cellulose to obtain an oil phase, dissolving 0.2g of emulsifying dispersant agricultural emulsion 1601 in 20ml of water to obtain a water phase, mixing the oil phase and the water phase, and ultrasonically emulsifying for 2min at 585W by using an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 500 nm.

Homogenizing the O/W type primary emulsion at 600Pa for 40min to obtain fine emulsion with droplet size of 50 nm.

And stirring the miniemulsion for 24 hours at 500rpm by using an electric stirrer to volatilize the organic solvent to obtain the nano pesticide mother liquor.

0.1g of thickening agent (0.05g of xanthan gum and 0.05g of aluminum magnesium silicate) is added into the nano pesticide mother liquor and evenly mixed to obtain the nano pesticide water suspending agent 26.

EXAMPLE 27 preparation of solid pesticide nanopowder 27

Dissolving 30g of pesticide active ingredient lambda-cyhalothrin in 260ml of organic solvent dichloromethane, adding 20g of capsule wall material cellulose to obtain an oil phase, dissolving 13g of emulsifying dispersant (6.5g of polyvinyl alcohol and 6.5g of agricultural emulsion 1601) in 400ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 30min at 22000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 900 nm.

Homogenizing the O/W type primary emulsion for 2h at 100Pa by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 500 nm.

And stirring the miniemulsion for 10 hours at 1500rpm by using an electric stirrer to volatilize the organic solvent to obtain the nano pesticide mother liquor.

And (2) centrifuging the nano pesticide mother liquor for 10min at 15000rpm by using a high-speed refrigerated centrifuge, then performing spray drying for 1.5s at the air inlet temperature of 30 ℃ and the air outlet temperature of 30 ℃ by using a spray dryer to obtain solid powder, adding 350g of solid filler diatomite and 15g of adjuvant TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 27.

EXAMPLE 28 preparation of Nanospermatism aqueous suspension 28

Dissolving 30g of pesticide active ingredient lambda-cyhalothrin in 260ml of organic solvent dichloromethane, adding 20g of capsule wall material cellulose to obtain an oil phase, dissolving 13g of emulsifying dispersant polyvinyl alcohol in 400ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 20min at 25000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 900 nm.

Adding 15g of thickening agent (7.5g of gelatin and 7.5g of magnesium aluminum silicate) and 15g of auxiliary agent TERSPERSE 2020 into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 28.

EXAMPLE 29 preparation of solid pesticide nanopowder 29

Dissolving 15g of pesticide active ingredient abamectin in 200ml of organic solvent dichloromethane, adding 15g of capsule wall material polylactic acid to obtain an oil phase, dissolving 10g of emulsifying dispersant (5g of polyvinyl alcohol and 5g of agricultural emulsion 1601) in 300ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 3min at 28000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

Centrifuging the nanometer pesticide mother liquor at 10000rpm for 20min by a high-speed refrigerated centrifuge, pre-freezing for 4h at-50 ℃ by a freeze dryer, keeping at-60 ℃ for 24h to obtain solid powder, adding 250g of solid filler kaolin, and uniformly mixing to obtain nanometer pesticide solid powder 29.

EXAMPLE 30 preparation of aqueous pesticide suspension concentrate 30

Dissolving 15g of pesticide active ingredient abamectin in 200ml of organic solvent dichloromethane, adding 15g of capsule wall material polylactic acid to obtain an oil phase, dissolving 10g of emulsifying dispersant (5g of polyvinyl alcohol and 5g of agricultural emulsion 1601) in 300ml of water to obtain a water phase, mixing the oil phase and the water phase, and shearing and emulsifying for 40min at 10000rmp by using a high-speed shearing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

And adding 15g of thickening agent (7.5g of gelatin and 7.5g of magnesium aluminum silicate) into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 30.

EXAMPLE 31 preparation of solid pesticide nanopowder 31

Dissolving 20g of pesticide active ingredient abamectin in 220ml of organic solvent dichloromethane, adding 30g of capsule wall material polylactic acid to obtain an oil phase, dissolving 20g of emulsifying dispersant (10g of polyvinyl alcohol and 10g of agricultural emulsion 1601) in 350ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 60min at 30Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 18h at-60 ℃ to obtain solid powder, adding 300g of solid filler kaolin and 10g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 31.

EXAMPLE 32 preparation of aqueous suspension of Nano pesticide 32

Dissolving 20g of pesticide active ingredient abamectin in 220ml of organic solvent dichloromethane, adding 30g of capsule wall material polylactic acid to obtain an oil phase, dissolving 20g of emulsifying dispersant (10g of polyvinyl alcohol and 10g of agricultural emulsion 1601) in 350ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 40min at 40Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

And adding 10g of thickening agent (5g of xanthan gum and 5g of magnesium aluminum silicate) and 10g of auxiliary agent TERSPERSE 2020 into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspension 32.

EXAMPLE 33 preparation of solid Nano-pesticide powder 33

Dissolving 40g of pesticide active ingredient abamectin in 300ml of organic solvent dichloromethane, adding 40g of capsule wall material polylactic acid to obtain an oil phase, dissolving 30g of emulsifying dispersant (15g of polyvinyl alcohol and 15g of agricultural emulsion 1601) in 500ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 20min at 45Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

Centrifuging the nano pesticide mother liquor for 20min at 10000rpm by using a high-speed refrigerated centrifuge, then pre-freezing for 4h at-50 ℃ by using a freeze dryer, keeping the temperature for 12h at-60 ℃ to obtain solid powder, adding 400g of solid filler kaolin and 20g of auxiliary agent TERSPERSE 2020, and uniformly mixing to obtain the nano pesticide solid powder 33.

EXAMPLE 34 preparation of Nanospermatism aqueous suspension 34

Dissolving 40g of pesticide active ingredient abamectin in 300ml of organic solvent dichloromethane, adding 40g of capsule wall material polylactic acid to obtain an oil phase, dissolving 30g of emulsifying dispersant (15g of polyvinyl alcohol and 15g of agricultural emulsion 1601) in 500ml of water to obtain a water phase, mixing the oil phase and the water phase, and grinding and emulsifying for 5min at 50Hz by using a grinding and dispersing machine to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 400 nm.

20g of thickening agent (10g of xanthan gum and 10g of magnesium aluminum silicate) and 20g of auxiliary agent TERSPERSE 2020 are added into the nano pesticide mother liquor and uniformly mixed to obtain the nano pesticide water suspending agent 34.

EXAMPLE 35 preparation of solid pesticide nanopowder 35

Dissolving 0.5g of pesticide active ingredient abamectin in 20ml of organic solvent dichloromethane, adding 0.5g of capsule wall material polylactic acid to obtain an oil phase, dissolving 0.5g of emulsifying dispersant (0.25g of polyvinyl alcohol and 0.25g of lignosulfonate) in 50ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification at 650W for 20min by adopting an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 100 nm.

Homogenizing the O/W type primary emulsion for 2h at 1200Pa by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 10 nm.

And (2) centrifuging the nano pesticide mother liquor for 30min at 4000rpm by using a high-speed refrigerated centrifuge, then performing spray drying for 1s at the air inlet temperature of 100 ℃ and the air outlet temperature of 140 ℃ by using a spray dryer to obtain solid powder, adding 10g of solid filler diatomite, and uniformly mixing to obtain the nano pesticide solid powder 35.

EXAMPLE 36 preparation of Nanospermatism aqueous suspension 36

Dissolving 0.5g of pesticide active ingredient abamectin in 20ml of organic solvent dichloromethane, adding 0.5g of capsule wall material polylactic acid to obtain an oil phase, dissolving 0.5g of emulsifying dispersant (0.25g of polyvinyl alcohol and 0.25g of lignosulfonate) in 50ml of water to obtain a water phase, mixing the oil phase and the water phase, and performing ultrasonic emulsification for 25min at 637W by using an ultrasonic pulverizer to obtain an O/W type primary emulsion, wherein the particle size of droplets of the primary emulsion is 100 nm.

Homogenizing the O/W type primary emulsion for 1h under 1000Pa by a high-pressure homogenizer to obtain a fine emulsion, wherein the particle size of the droplets of the fine emulsion is 10 nm.

And adding 1g of thickening agent xanthan gum into the nano pesticide mother liquor, and uniformly mixing to obtain the nano pesticide water suspending agent 36.

Example optimized selection of Emulsifing dispersant for Emamectin benzoate NanoPestIcIde formulations

The procedure for the preparation of the primary emulsion in example 11 was followed, using polyvinyl alcohol and one of the following: EL 40, Span 60, Tween 80, Span 80, Tween 60, Nongru 500^#Agricultural milk 600^#"Nongru" 700^#Farm milk 1601^#And AEO-9 is used as an emulsifying dispersant to prepare an initial emulsion of the emamectin benzoate nano pesticide preparation, a nano laser particle size analyzer is adopted to test the particle size and the dispersion index (PDI) of the nano particles formed in the primary emulsification stage, the particle size and the dispersion index of the nano particles formed in the primary emulsification stage when different emulsifying dispersants are adopted are compared, and the optimal emulsifying dispersant is selected.

Table 1 shows the average particle size and dispersion index of the nanoparticles formed in the primary emulsification stage of the emamectin benzoate nano pesticide preparation prepared by using different emulsifying dispersants, and it can be seen from table 1 that when EL 40 is used as the emulsifying dispersant, the average particle size and dispersion index of the nanoparticles in the primary emulsion of the emamectin benzoate nano pesticide preparation are smaller (better dispersibility), and the emulsification degree is the best, so the EL 40 is preferably used as the emulsifying dispersant in the present invention.

Table 1 mean particle size and dispersion index of nanoparticles in methylamino avermectin benzoate nano pesticide preparation primary emulsion prepared with different emulsifying dispersants

Note: s.d. represents the standard deviation.

Test example 1 testing of morphology, particle size and particle size distribution of nano-pesticide preparation

The shapes of the nano pesticide preparations prepared in the above embodiments are observed by a transmission electron microscope and a scanning electron microscope respectively, and the particle size distribution thereof are tested by a nano laser particle sizer.

Fig. 1 is a transmission electron microscope picture and a particle size distribution diagram of the lambda-cyhalothrin nano pesticide preparation prepared in example 17 of the present invention. As seen from fig. 1, the lambda-cyhalothrin nano pesticide preparation prepared by the embodiment of the invention has a spherical shape with an average particle size of 98.18nm (as shown in (a) and (b) of fig. 1).

Fig. 2 is a scanning electron microscope picture of the avermectin nano-pesticide preparation prepared in example 1 under 1000 times (a), 3000 times (b) and 8000 times (c) magnification. As seen from fig. 2, the avermectin nano pesticide preparation prepared by the embodiment of the invention is spherical, and the average particle size is 487nm (as shown in (a), (b) and (c) in fig. 2).

Fig. 3 is scanning electron microscope pictures of emamectin benzoate nano-pesticide preparations prepared in example 11 of the present invention under 8000 times (fig. 3(a)) and 20000 times (fig. 3(b)) magnification, respectively. As seen from fig. 3, the emamectin benzoate nano-pesticide preparation prepared by the embodiment of the invention is spherical, and the average particle size is about 100 nm.

Fig. 4 and 5 show electron microscope pictures and particle size distributions of avermectin nano-pesticide preparations prepared in examples 7, 8, 9 and 10 of the present invention, and as shown in fig. 4, the avermectin nano-pesticide preparations prepared in the examples of the present invention are all spherical (as shown in (a), (b) (c) and (d) of fig. 4), and have particle sizes of 344nm (a), 460nm (b), (c) and 827nm (d), respectively (as shown in fig. 5). Therefore, by adopting the method, the abamectin nano pesticide preparation with different particle sizes can be obtained by changing the component distribution ratio and the process conditions, so that the particle size of the abamectin nano pesticide preparation can be adjusted according to the specific application scene.

Test example 2 emamectin benzoate nanopartical distribution test

The emamectin benzoate nano pesticide preparation prepared in the example 14 is sprayed on clean cucumber leaves, and after drying, the distribution of the nano pesticide preparation on the leaves is observed by adopting an environment scanning electron microscope.

Fig. 6 shows the distribution of the emamectin benzoate nano-pesticide preparation on cucumber leaves, and it is seen from the figure that the nano-pesticide preparation prepared by the embodiment of the invention has good dispersibility and uniform distribution on the cucumber leaves.

Test example 3 sustained-release Performance test of Avermectin NanoPestIcIde preparation

The avermectin nano-pesticide preparation prepared in the above examples 7, 8, 9 and 10 and the sustained release performance of the original avermectin are respectively tested (the content of avermectin released in the nano-pesticide preparation is tested by a dialysis method at different release times by adopting an ultraviolet-visible spectrophotometer), and a cumulative release amount-time curve is prepared.

Fig. 7 is a slow release curve of the nano avermectin pesticide preparation (A, B, C, D) and the original avermectin drug (E) prepared in examples 7, 8, 9 and 10 of the present invention within 240 hours, and it is seen from the graph that the nano avermectin pesticide preparation prepared in the examples of the present invention has an accumulated release amount of about 0 to 19% within the first 24 hours, and then the release rate is slowed down, and the accumulated release amount reaches about 53 to 80% within 240 hours; the accumulated release amount of the abamectin technical reaches about 94 percent in the first 24 hours. Therefore, compared with the abamectin technical product, the abamectin nano pesticide preparation prepared by the embodiment of the invention has the advantages of obviously prolonged release time and obvious slow release property. In addition, the particle sizes of the avermectin nano-pesticide preparation prepared by the embodiment of the invention are 344nm (A), 460nm (B), 615nm (C) and 827nm (D) (shown in figure 4), respectively, and as shown in figure 7, the slow release time of the avermectin nano-pesticide preparation prepared by the embodiment of the invention is reduced along with the increase of the particle size. Therefore, by adopting the method of the invention, the nano pesticide preparations with different slow release characteristics can be obtained by adjusting the particle size, so as to meet the requirements of different application scenes and pest and disease occurrence rules.

In addition, tests show that the nano pesticide preparation prepared by other embodiments of the invention also has better slow release performance.

Test example 4 photolysis resistance test of avermectin nano-pesticide formulation

The avermectin nano-pesticide preparation prepared in the example 7 and a commercially available avermectin water dispersible granule (Beijing Huajon biology, Kaiwei) are respectively irradiated for 12h, 24h, 36h, 48h, 60h and 72h under 500W ultraviolet light, and ultraviolet degradation resistance of the avermectin nano-pesticide preparation prepared in the example 7 and the commercially available avermectin water dispersible granule is respectively tested by adopting a pesticide light stability test box to prepare a photolysis rate-time curve.

As shown in fig. 8, compared with the conventional commercially available abamectin water dispersible granule, the nano-pesticide preparation of abamectin prepared by the embodiment of the invention has significantly reduced photolysis rate under ultraviolet light irradiation and has good ultraviolet light degradation resistance. The method can effectively protect the abamectin pesticide from photodegradation, thereby greatly improving the effective utilization rate and bioavailability, reducing the application frequency and dosage and being beneficial to environmental and ecological safety.

In addition, tests show that the nano pesticide preparation prepared by other embodiments of the invention also has excellent ultraviolet degradation resistance.

While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

1. A method of preparing a nano-pesticide formulation, the method comprising: the components of the nano pesticide preparation are emulsified to form a primary emulsion, and then are homogenized under high pressure to form a fine emulsion, so that the nano pesticide preparation is prepared, and the preparation method comprises the following steps:

step d: mixing the nano pesticide mother liquor obtained in the step c with an excipient and an auxiliary agent to obtain a nano pesticide preparation,

wherein the step a comprises: dissolving pesticide active ingredients in an organic solvent, adding a capsule wall material to obtain an oil phase, dissolving an emulsifying dispersant in water to obtain a water phase, mixing the oil phase and the water phase, and emulsifying to obtain an O/W type primary emulsion; the capsule wall material is a degradable high polymer material, and is selected from one or more of cellulose and derivatives thereof, chitosan, polylactic acid and modified starch;

the emulsification in the step a is one or more of ultrasonic emulsification, shearing emulsification and grinding emulsification; wherein the ultrasonic emulsification is carried out by adopting an ultrasonic crusher, and the power of the ultrasonic crusher is 325-637W; the ultrasonic emulsification time is 5-25 min; the shearing emulsification is carried out by adopting a high-speed shearing machine, and the shearing rotating speed of the high-speed shearing machine is 22000-28000 rmp; the shearing time is 3-30 min; the grinding emulsification is carried out by adopting a grinding dispersion machine, and the frequency of the grinding emulsification is 40-50 Hz; grinding for 5-40 min; the particle size of the primary emulsion liquid drop is 100-900 nm;

the high-pressure homogenization in the step b is carried out by adopting a high-pressure homogenizer, and the pressure of the high-pressure homogenization is 600-1000 Pa; the high-pressure homogenization time is 10min-1 h; the particle size of the droplets of the miniemulsion is 10-600 nm;

stirring by adopting an electric stirrer in the step c at the stirring speed of 1000-; stirring for 10-20 h;

the nano pesticide preparation is prepared from the following components in parts by weight:

active ingredients of the pesticide: 0.1 to 40 portions

Capsule wall material: 0.1 to 40 portions

Emulsifying and dispersing agent: 0.2 to 30 portions of

Organic solvent: 10-300 parts

Water: 20-500 parts of

Excipient: 0.1 to 400 portions

Auxiliary agents: 0 to 20 portions of the components are added,

the pesticide active ingredient is an insecticide selected from one or more of the following: abamectin, emamectin benzoate, lambda-cyhalothrin, chlorantraniliprole, spinosad, indoxacarb, clothianidin, carbosulfan, triazophos, dinosaur, acanthofos, chlorpyrifos, bifenthrin, cyphenothrin, ethofenprox, deltamethrin, fenvalerate, cyhalothrin, tefluthrin, fosthiazate, phoxim, imidacloprid and thiamethoxam.

2. The method of claim 1, wherein the nano-sized pesticide formulation is spherical.

3. The method for preparing the nano pesticide formulation according to claim 1 or 2, wherein the nano pesticide formulation is a nano pesticide aqueous suspension, the excipient is a thickener, and the step d comprises: and d, directly adding a thickening agent and an auxiliary agent into the nano pesticide mother liquor obtained in the step c, and uniformly mixing to obtain the nano pesticide water suspending agent.

4. The preparation method according to claim 1 or 2, wherein the nano pesticide preparation is nano pesticide solid powder, the excipient is a solid filler, and the step d comprises: and c, centrifuging and drying the nano pesticide mother liquor obtained in the step c to obtain solid powder, adding a solid filler and an auxiliary agent, and uniformly mixing to obtain the nano pesticide solid powder.

5. The method according to claim 1, wherein the emulsification in step a is one or more of shear emulsification and grinding emulsification; the particle size of the primary emulsion liquid drop is 100-500 nm;

wherein the ultrasonic emulsification is carried out by adopting an ultrasonic crusher, and the power of the ultrasonic crusher is 585W; the ultrasonic emulsification time is 15 min;

wherein the shearing emulsification is carried out by adopting a high-speed shearing machine, and the shearing rotating speed of the high-speed shearing machine is 28000 rmp; the shearing time is 15 min;

wherein the grinding emulsification is carried out by adopting a grinding dispersion machine, and the frequency of the grinding emulsification is 50 Hz; grinding for 15 min;

in the step b, the pressure of high-pressure homogenization is 900 Pa; homogenizing under high pressure for 15 min; the particle size of the droplets of the miniemulsion is 10-100 nm;

in the step c, the stirring speed is 1500 rpm; the stirring time is 12 h;

when the nano pesticide preparation is nano pesticide solid powder, in the step d, a high-speed refrigerated centrifuge is adopted for centrifuging for 10-30min at the rotation speed of 4000-15000 rpm;

when the nano pesticide preparation is nano pesticide solid powder, the drying in the step d is spray drying or freeze drying, wherein the spray drying is carried out by adopting a spray dryer, the conditions of the spray drying are that the air inlet temperature is 30-300 ℃, the air outlet temperature is 30-140 ℃, and the drying time is 1-1.5 s; the freeze drying is carried out by adopting a freeze dryer, and the condition of freeze drying is pre-freezing for 4h at-50 ℃ and keeping for 12-24h at-60 ℃.

6. The method as claimed in claim 5, wherein when the nano pesticide preparation is nano pesticide solid powder, the step d comprises centrifuging at 4000-15000rpm for 20-30min by using a high-speed refrigerated centrifuge;

the freeze drying is carried out by adopting a freeze dryer, and the condition of freeze drying is pre-freezing for 4h at-50 ℃ and keeping for 12h at-60 ℃.

7. The preparation method according to claim 6, wherein when the nano pesticide preparation is nano pesticide solid powder, the step d is performed by centrifuging at 15000rpm for 20min by using a high-speed refrigerated centrifuge.

8. The method for preparing the nano pesticide preparation according to claim 2, wherein the nano pesticide preparation has a particle size of 20 to 500 nm.

9. The method for preparing the nano pesticide preparation according to the claim 8, wherein the particle size of the nano pesticide preparation is 100nm or less.

10. The method of claim 9, wherein the particle size of the nano pesticide formulation is less than 50 nm.

11. The preparation method of claim 3, wherein the nano pesticide aqueous suspension has a drug loading of 0.1-20%.

12. The preparation method according to claim 4, wherein the drug loading of the nano pesticide solid powder is 0.1-90%.

13. The preparation method according to claim 1, wherein the nano pesticide preparation is nano pesticide solid powder, wherein the excipient is a solid filler, and the nano pesticide solid powder is prepared from the following components in parts by weight:

active ingredients of the pesticide: 0.1 to 40 portions

Capsule wall material: 0.1 to 40 portions

Emulsifying and dispersing agent: 0.2 to 30 portions of

Organic solvent: 10-300 parts

Water: 20-500 parts of

Solid filler: 0.1 to 400 portions

Auxiliary agents: 0 to 20 portions of the components are added,

active ingredients of the pesticide: 0.1 to 40 portions

Capsule wall material: 0.1 to 40 portions

Emulsifying and dispersing agent: 0.2 to 30 portions of

Organic solvent: 10-300 parts

Water: 20-500 parts of

Thickening agent: 0.1 to 20 portions

Auxiliary agents: 0 to 20 portions of the components are added,

14. The method of claim 1, wherein the insecticide is selected from one or more of thiamethoxam, spinosad, chlorantraniliprole, abamectin, emamectin benzoate and lambda-cyhalothrin.

15. The preparation method according to claim 13, wherein the emulsifying dispersant is one or more of agricultural emulsifiers and dispersants, and the agricultural emulsifiers are selected from one or more of OP series, NP series, EL series, Tween series, Span series, AEO series, agricultural milk series, polyvinyl alcohol, polyethylene glycol fatty acid ester, polyvinyl pyrrolidone and polyethylene glycol oleate;

the dispersing agent is selected from one or more of carboxylate, sulfate, sulfonate, phosphate ester salt and alkylphenol polyoxyethylene;

the auxiliary agent is selected from one or more of a preservative, a defoaming agent, an antifreeze agent, a pH regulator and a wetting dispersant;

the antifreeze is selected from one or more of ethylene glycol, propylene glycol, glycerol, isopropanol and urea;

the defoaming agent is selected from one or more of organic silicon defoaming agents and low-carbon alcohol defoaming agents;

the thickening agent is selected from one or more of xanthan gum, Arabic gum, gelatin, cellulose and derivatives thereof, diatomite, polyvinyl alcohol, sodium polyacrylate, dextrin, magnesium aluminum silicate and silica gel;

the organic solvent is selected from one or more of dichloromethane, trichloromethane, vegetable oil, petroleum ether and aliphatic hydrocarbon solvent oil;

the solid filler is selected from one or more of diatomite, kaolin, talcum powder, montmorillonite, white carbon black, corn starch and sepiolite.

16. The method for preparing the emulsion of claim 15, wherein the agricultural emulsifier is one or more selected from Tween series, polyvinyl alcohol and agricultural milk series emulsifiers;

the dispersing agent is selected from one or more of fatty alcohol polyoxyethylene ether carboxylate, lauryl sodium sulfate, lignosulfonate, sodium dodecyl sulfonate, maleic rosin polyoxyethylene-oxypropylene ether sulfonate and dodecyl ether phosphate;

the auxiliary agent is selected from one or more of an antifreeze agent, a defoaming agent and a wetting dispersant;

the antifreeze agent is ethylene glycol;

the defoaming agent is an organic silicon defoaming agent;

the thickening agent is selected from one or more of xanthan gum, gelatin, magnesium aluminum silicate, cellulose and derivatives thereof and polyvinyl alcohol;

the organic solvent is dichloromethane;

the solid filler is selected from one or more of kaolin, corn starch and white carbon black.

17. The preparation method according to claim 16, wherein the agricultural emulsifier is selected from one or more of polyvinyl alcohol, agricultural milk 300 series, agricultural milk 500 series, agricultural milk 600 series, agricultural milk 700 series, and agricultural milk 1600 series emulsifiers;

the dispersant is selected from one or more of lignosulfonate, sodium dodecyl sulfate and sodium dodecyl sulfate.