Ma Chao, Zhu Bingyu, Duyou Chen, Feng Liu
(Institute of Plant Protection, Shandong Agricultural University, Shandong Tai'an 271018)
Abstract: The integrated use of the ratio method and the method of sub-cyhalothrin 2.5% microemulsion formulation was studied in a relatively short period of time selected the better of the microemulsion formulation. Including the use of methanol and benzene solvent to 3:1 mix ratio, mass fraction of 10%; emulsifier agent 500 # and 602 # to 3:7, the mass fraction of 18%; fill with deionized water to 100. The preparation of the technical indicators are qualified to meet production needs.
Keywords: Cyhalothrin, microemulsion, the ratio method, points system
Key words: TQ450.6 Document code: A Article ID :1000-2324 (2007) 03-0411-04
Received date :2006-03-20
Author: Ma Chao, (1984 -), male, master. Research interests include the development of pesticides and pesticide residues.
* Corresponding author: Author for correspondence. E-mail: fliu@sdu.edu.cn
STUDUY ON THE FORMULATION OF 2.5% LAMBDA-CYHALOTHRIN ME WITH PROPORTIONAL AND BISECTIONAL METHOD
MA Chao, ZHU Bing-yu, DU You-chen, LIU Feng *
(College of Plant Protection, Shandong Agricultural University, Taian 271018, China)
Abstract: Using proportional and bisectional method, the formulation of 2.5% Lambda-cyhalothrin ME was studied rapidly, which had good character and low cost. The best solvent was the mixture of methanol and benzene (3:1, m / m), which was 10% weight of total composition; the emulsifier was the mixture of 500 # and 600 # (3:7 m / m), occupied 18% weight, the other component was water.All specifications of the formulation were up to grade.
Key words: Lambda-cyhalothrin; Microemulsion; Proportional method; Bisectional method
In the processing of multi-component pesticide formulations, How to Arrange test is a very important issue. The usual practice is to test people first, based on experience to develop a basic formula, prepared according to this formula to the process, then the sample preparation according to the measured performance index formula of the adjustment, optimization, this is often more time-consuming, and the final formula not the most economical and reasonable, and sometimes fruitless, so experimental design is particularly important. Proportion method and the points system is relatively simple test of two methods, Weifang Lin, etc. be applied to the EC, the water emulsion formulations 〔3,4〕 screening, not only reduced the number of tests, reduce test time, to overcome the blindness, to facilitate quickly get a better formula. In this paper, the scaling method and the method of sub-2.5% Cyhalothrin Microemulsion formulations were studied.
1 Materials and methods
1.1 Materials
Cyhalothrin 96% TC (Shandong Texas Pesticide Chemical Co., Ltd. Hang Dong), # 500 milk farmers, dairy farmers 600 #, NP-7, NP-10, Tween -20, Tween -40, spit Temperature -80 (MSC Chemical Co., Ltd. Jiangsu).
1.2 The main instruments and equipment
Shimadzu GC-14B gas chromatograph
1.3 Microemulsion preparation methods
Phase transfer method. At room temperature, the Lambda-cyhalothrin TC soluble "solvent", the dissolved completely, add the emulsifier and then mixed evenly while stirring deionized water, gradually from the emulsion water-oil into water oil-in type of transparent micro-emulsion.
1.4 Detection of key performance indicators
Emulsion stability, transparency temperature range, hot and cold storage stability of the determination with reference to the literature [5], microemulsion quality standards and testing methods.
2 Results and analysis
2.1 Determination of Solvent
Cyhalothrin as the original drug is a solid powder, so choose the right solvent is obtained by passing the premise of microemulsion. In common organic solvents, methanol and benzene prices low and the solubility of the larger Lambda-cyhalothrin, and the higher polarity of methanol, the polarity of benzene is very low, can be mixed by the two polar appropriate mixed solvent.
By using the same amount (mass fraction of 20%) of the same surfactant NP-10 as a fixed component, methanol and benzene were investigated (both 10% wt) ratio of the different microemulsion mixing stability. Results (see Table 1) show that the solvent system of methanol and benzene in the mass ratio of 3:1, the best quality micro emulsion, can be further additives and solvent through the screening of the best micro-emulsion formula.
Table 1, different proportions of methanol and benzene performance of micro-emulsion
Table 1 The effect of mixture solvent of methanol and benzene on the stability of formulation
Methanol: benzene (m / m)
methand: Benzene (m / m)
Appearance
Appearance
Transparent temperature range / ℃
Range of transarent / ℃
Stabilization time of cold storage (0 ℃) / d
Cold storage at 0 ℃ / d
4:1
Transparent
3 ~ 73
3
3:1
Transparent
3 ~ 70
7
2:1
Translucent
5 ~ 75
1
1:1
Milky
-
-
1:2
-
-
-
2.2 The choice of surfactant
Preparation of non-ionic emulsifier alone micro-emulsion to the temperature-sensitive, so generally use anionic emulsifier with matching [6,7]. The anionic emulsifier 500 # as a fixed component, in accordance with the non / negative ratio of 1:1 mixed emulsifier to the method selected varieties of non-ionic emulsifier, in the micro-emulsion system, the mass fraction of 20%. Results (see Table 2) shows that some formulations can be micro-emulsion, but there is a big difference in stability, in which parties choose emulsifier 600 # T-60 and preparation of the indicators are qualified formulations, but the emulsifier 600 # dilution formula, better stability, so choose the next step emulsifier 600 # test.
Table 2 2.5% non-ionic emulsifier on Cyhalothrin Microemulsion Stability Performance
Table 2 The effect of nonionic surfactant and calcium dodecylbenzene sulfonate mixture on the stability of formulation
Emulsifier
Emulsifier
Transparent temperature range (℃)
Range of transparent temperarture / ℃
Stabilization time of cold storage (0 ℃, d)
Cold-strorage at ℃ / d
Heat storage stability (54 ℃, 14d)
Hot-storage at 54 ℃ / 14d
Dilution Stability (min)
Dilutim stability / min
NP-7
3 60
2
Translucent
10
NP-10
-2 63
2
Transparent
5
600 #
-2 90
14
Transparent
30
T-20
10 ~ 75
6
Translucent
10
T-60
-3 80
14
Transparent
24
T-80
5 ~ 85
14
Transparent
13
2.3 The choice of solvent
With the solvent and the preparation of microemulsion surfactant, respectively, by adding butanol and hexanol (mass fraction is 2%), found that after adding n-butanol the temperature range of the transparent microemulsion and diluted greatly improved performance, it helps butanol solvent used.
2.4 Determination of optimum formulation
According to the above two options are two basic experiments A and B formulations the oil phase, as shown in Table 3.
Table 3 2.5% Cyhalothrin two basic recipe ME
Table 3 Two basic formulations of 2.5% Lambda-cyhalothrin ME
Components
Composition
A recipe oil content (%)
Component (%, m / m)
Formula B oil content (%)
Component (%, m / m)
Original drug (96%)
2.6
2.6
Methanol
7.5
7.5
Benzene
2.5
2.5
500 #
20
0
Farmers Milk # 600
02
0
Butanol
4
0
With the proportion method in a mass ratio A and B will mix the oil phase, and then fill with deionized water to 100g. Study focused on the appearance of preparation, dilution stability and transparent quality control of the temperature range of the three main indicators. The results in Table 4.
Table 4 Screening with a ratio of 2.5% Cyhalothrin ME formula results
Table 4The results of 2.5% the formulation with proportionalmethod
Level
Level
Ratio
Proportion
A Oil
(%)
B oil
(%)
Appearance
Appearence
Dilution stability time / min
Dilution stability time / min
Transparent temperature range (℃)
range of transparent temperature / ℃
1
0:10
36.6
0
Turbid
-
-
2
9:1
32.94
3.26
Turbid
-
-
3
8:2
29.28
6.52
Turbid
-
-
4
7:3
25.62
9.78
Translucent
5
10 ~ 75
5
6:4
21.96
13.04
Translucent
10
5 ~ 75
6
5:5
18.30
16.30
Translucent
25
3 ~ 76
7
4:6
14.64
19.56
Transparent
40
0 ~ 75
8
3:7
1098
22.82
Transparent
120
-5 ~ 80
9
2:8
7.32
26.08
Transparent
80
-2 76
10
1:9
3.66
29.34
Transparent
30
2 80
11
0:10
0
32.6
Turbid
-
-
Table 4 shows, in the A, B oil phase ratio of 3:7 of the best performance when the preparations, so choose the level of 8 as a 2.5% Cyhalothrin Microemulsion based formulation for further optimization. In this formula (100g): the original drug 2.6g, methanol, 7.5g, benzene, 2.5g, farm milk 500 # 6g, farm milk 600 # 14g, n-butanol 1.2g, fill with deionized water to 100g.
Then determined by preparation of sub-optimal formula, the points system factors into 2 conditions: (1) 500 # +600 # dairy farmers as a factor A; (2) to farmers milk is 500 # +600 # + butanol as a factor B.
In the selection process additives, emulsifier has been taken in 20% of good results to reduce the dosage selection for further optimization. Microemulsion emulsifier generally not less than 10%, so to determine the amount of emulsifier of 10 to 20%, 15% of the first study of the performance test results in Table 5.
Table 5 in 18% of the amount of emulsifier factors A, B of the test results on the points system
Table 5 The result of the formulation with bisectional method when the emulsion at 18%
Factors
Factor
Amount (%)
Dosage (%, m / m)
Appearance
Appearence
Dilution stability time / min
Dilution stability time / min
Transparent temperature range (℃)
range of transparent temperature / ℃
A
15
Transparent
35
-3 75
B
15.9
Transparent
30
-1 76
The results showed that 15% of the amount of emulsifier, preparation of the dilution range of performance and transparent failure temperature, indicating that the amount of less than normal, to increase the amount of the above two factors and then up to 4 times the required tests can be, that is, the amount of emulsifier 16%, 17%, 18%, 19% cases, the test results shown in Table 6.
Table 6 16% emulsifier, 17%, 18%, 19% of factor A, B of the experimental results on the points system
Table 6 The result of the formulation with bisectional method when the emulsion at 16%, 17%, 18% and 19%
Factors
Factor
No.
Number
Amount (%) Dosage
(%, M / m)
Appearance
Appearence
Dilution stability time / min
Dilution stability time / min
Transparent temperature range (℃)
range of transparent temperature / ℃
A
1
16
Transparent
40
-3 75
2
17
Transparent
50
-4 76
3
18
Transparent
100
-5 ~ 75
4
19
Transparent
110
-5 ~ 76
B
1
16.96
Transparent
38
-3 75
2
18.02
Transparent
45
-2 76
3
19.08
Transparent
100
-4 75
4
20.14
Transparent
110
-4 76
The results showed that 18% of the amount of factor A, factor B when the amount of 19.08% of the recipes are good recipes are shown in Table 7.
Table 7 Optimization of formulation using the results of sub-
Table 7The optimized result with bisectional method
Components
Composition
Formula 1 (A) content (%)
Component (%, m / m)
Formula 2 (B) content (%)
Component (%, m / m)
Original drug (96%)
2.6
2.6
Methanol
7.5
7.5
Benzene
2.5
2.5
Farmers Milk # 500
5.4
5.4
Farmers Milk # 600
12.6
12.6
Butanol
1.2
1.08
Deionized water
68.2
68.32
Hot and cold on the above two formulations storage stability test results shown in Table 8.
Table 8 verify the results of two formulations
Table 8The validate results of the two formulations
Formula
Formulation
Heat storage physical stability (54 ℃, 14d)
Hot-storage appearance at54 ℃
Decomposition rate of heat storage (54 ℃, 14d) /%
Hot-storage (Decompose rate%)
Stability of cold storage (0 ℃) / d
Cold-storage at 0 ℃
1
Transparent uniform
2.0
14
2
Transparent uniform
1.9
14
Validation results show that the formula 1,2 can meet performance requirements, consider choosing from the raw material cost formula 2 as the discount formula.
3 Conclusion
2.5% Cyhalothrin Microemulsion formulation of the screening method and the integrated use of the ratio of sub-law, combined with determination of the stability index formulation, significantly shorten the development time of formulation, greatly reducing the workload. Formulation of the method, especially for multi-component pesticide formulation study provides a better screening ideas.
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