Background and overview[1][2]
Fenthion is also known as tiguvon. Broad spectrum, low toxicity organophosphorus pesticide. It has stronger insecticidal effect than trichlorfon, lower toxicity to humans and animals, no accumulation effect, stable properties, and long-lasting efficacy. It is a specific drug that kills the larvae of Bosphorus. It is also effective against the second stage of transitional stage larvae. However, the drug should be avoided when the larvae migrate to the spinal cord, otherwise it will cause paralysis. Also used to kill lice, ticks, flies, etc. Use methods such as spraying or pouring on the back to administer the medicine.
The pure product is a colorless oily liquid, and the industrial product is a yellow-brown oily liquid. The product is a 50% emulsion with a garlic smell. It is relatively stable to light, heat and alkali, and can be mixed with weakly alkaline pesticides, but it should be used as needed. It has contact and stomach poisoning effects, and has a slight systemic effect, with a long residual effect. It is moderately toxic to higher animals, and the oral lethal dose to rats is 216mg/kg. Using 100-150g of 50% emulsion per acre (diluted 800-1000 times) has a good control effect on tea weevil and green scale weevil. The safe interval is tentatively set at 10 to 15 days.
Detection[3]
Fenthion is an organophosphorus pesticide with a moderately toxic structure, broad insecticidal spectrum, long residual effect, and is widely used. Fenthion residues are harmful to humans and livestock, and the widespread use of fenthion will inevitably cause harm to environmental health and the safety of agricultural products. Therefore, countries around the world have strictly regulated the maximum allowable residues of fenthion in agricultural products, and my country is no exception. At present, the detection method of fenthion is mainly traditional chromatographic method. This method is highly dependent on machines, has high cost, complex operation and long analysis time. It is difficult to meet the requirements of high-throughput, rapid and online detection.
CN200710021377.5 In view of the shortcomings of the existing chromatographic instrument technology that the fenthion detection method is complicated in operation, high in detection cost, and low in detection efficiency, a fenthion ELISA detection method is provided to find a solution for fenthion pesticide residues. A fast, accurate, simple and low-cost ultra-trace detection method. The detection of fenthion pesticide residues is highly accurate, highly sensitive, simple, fast and cheap. Detection methods include:
(1) Preparation of polyclonal antibodies to fenthion
The immunogen “fenthion-bovine serum albumin conjugate” of fenthion artificial antigen was used to immunize New Zealand white rabbits with conventional immunization methods. The rabbit antiserum prepared against fenthion is fenthion. Polyclonal antibodies;
(2) Covered
Use fenthion artificial antigen-coated antigen “fenthion-ovalbumin conjugate” 1.2 μg/mL. Add 50 μL to each well of the microanalysis plate, refrigerate at 4°C overnight, pour it out, and wash as usual. Wash 3 to 6 times with buffer phosphate-Tween buffer, invert, and pat dry on absorbent paper;
(3) Closed
1% gelatin is used as a sealer, 100 μL per well of the micro-analysis plate, react at 37°C for 1 hour, pour it out, wash it 3 to 6 times with conventional washing buffer phosphate-Tween buffer, invert it, and place it on absorbent paper. Pat dry;
(4) Add antibodies and a mixture of antibodies and samples to be tested
Mix thoroughly the 8000-fold diluted fenthion antiserum with the sample to be tested and the blank antigen-antibody reaction solution, that is, conventional phosphate-Tween buffer, in equal volumes, and then add 50 μL per well to the microanalysis plate, 37 React at ℃ for 1 hour, pour out, wash 3 to 6 times with conventional washing buffer phosphate-Tween buffer, invert, and pat dry on absorbent paper;
(5)Add enzyme-labeled secondary antibody
Dilute the commercial HRP-goat anti-rabbit IgG 2000 times with the conventional washing buffer phosphate-Tween buffer at pH 7.4 and 0.15 mol/L. Add 50 μL to each well of the microanalysis plate and react at 37°C for 1 time. hour, pour out, wash 3 to 6 times with regular washing buffer phosphate-Tween buffer, invert, and pat dry on absorbent paper;
(6) Color development
Add 50 μL of tetramethylbenzidine substrate solution to each well of the microanalysis plate, and develop the color reaction at 37°C for 10 minutes
(7) Terminate the reaction and read
Add 2 mol/L sulfuric acid, add 25 μL to each well of the microanalysis plate, terminate the color reaction, read the absorbance value at 450 nm on the enzyme linker, use the blank matrix as a positive control absorbance value Bo, and the absorbance value of the sample to be tested B;
(8)Data processing
Calculate the binding rate B/Bo and Logit(B/Bo),
Logit(B/Bo)＝Ln[(B/Bo)/(1-B/Bo)] Formula 1
Substitute as follows�Equation for detecting smooth opening agent:
Logit(B/Bo)＝-0.7575LogC-1.4928 Formula 2
Thermoplastic elastomer, where C is the concentration of fenthion measured in the well of the microanalysis plate, which can be obtained by formula 1 and formula 2;
X=n×2C, n is the multiple of dilution of the sample before reaction Formula 3
The residual amount of fenthion expressed as concentration X in the sample to be tested can be obtained by formula 3.
In the above ELISA detection method for fenthion pesticide residues, the methanol content in the phosphate-Tween buffer of the antigen-antibody reaction solution is 5%, the pH value is 7.4, and the ionic strength is 0.15mol/L. 50 μL per well. Equation 2 can be corrected by the competition curve of the standard concentration series of fenthion.
Apply[2]
It is a broad-spectrum low-toxicity organophosphorus insecticide and is the main drug for the prevention and treatment of ectoparasitic diseases in livestock and poultry. It enters the insect body through contact killing and gastric poisoning, and kills parasites inside and outside the host. The killing effect is 5 times stronger than trichlorfon. In addition to killing horse stomach larvae, livestock gastrointestinal nematodes, and lice, ticks, fleas, mosquitoes, flies, etc., it has special effects on bovine nymph larvae (whether it is the third stage larvae or the second stage larvae), Used during the egg-laying period of cattle flies, good results can be achieved.
Due to its stable properties, one dose can maintain its efficacy for about 2 months. It has low toxicity to humans and animals. The LD50 for oral administration in rats is 177-375 mg/kg and for subcutaneous injection is 345-410 mg/kg. It has no accumulation effect in the body. After the drug is administered to dairy cows, the residual amount in the milk is very low. It can be used in dairy cows, but milking should be done 6 hours after administration. It is used to kill bovine fly larvae. In addition to being effective against third-stage fly larvae that are effective with general drugs, it is also effective against transitional stage fly larvae. It can kill lice, ticks, fleas, mosquitoes, flies, etc. on the surface of livestock.
Main reference materials
[1] Chinese Tea Dictionary
[2] New Practical Manual of Veterinary Drugs
[3] CN200710021377.5 Immunological detection method of pesticide fenthion residues
