阅读说明：本技术 一种氟虫腈人工抗原、制备方法及应用 (Fipronil artificial antigen, preparation method and application ) 是由 刘俊伟 蔡岩 刘辰辰 吴雨晴 杨梦瑶 于 2021-10-18 设计创作，主要内容包括：本发明公开一种氟虫腈人工半抗原、制备方法及应用,以一种氟虫腈的结构类似物作为半抗原制备出一种特异性较好的人工抗原,并在此基础上制备出抗氟虫腈的高特异性抗体,进而应用于氟虫腈残留量的检测；经检验发现,制得的抗氟虫腈抗体具有极高的灵敏度。由于氟虫腈残留问题严重危害了食品安全,并会对人体造成很大的危害；因此,对氟虫腈及其代谢产物的快速检测有着重要意义。(The invention discloses a fipronil artificial hapten, a preparation method and application, wherein an analogue of fipronil is used as a hapten to prepare an artificial antigen with better specificity, and a high specificity antibody for resisting fipronil is prepared on the basis, so that the artificial hapten is applied to detection of fipronil residue; the detection shows that the prepared anti-fipronil antibody has extremely high sensitivity. The food safety is seriously harmed due to the residue problem of fipronil, and great harm is caused to human bodies; therefore, the method has important significance for quickly detecting the fipronil and the metabolite thereof.)

1. An artificial hapten of fipronil, which is characterized in that: the structure is shown in a formula 1,

formula 1;

wherein n is less than or equal to 6.

2. A method for preparing the fipronil artificial hapten as claimed in claim 1, characterized in that: chemically synthesizing 2, 6-dichloro-4-trifluoromethyl phenylhydrazine and a compound shown in a formula 2 to obtain a compound shown in a formula 3; then reacting the compound shown in the formula 3 with alkali to prepare a compound shown in a formula 1, namely fipronil artificial hapten;

formula 2;

formula 3;

the alkali is LiOH, NaOH or KOH.

3. The method for preparing fipronil artificial hapten according to claim 2, which is characterized in that: the method comprises the following specific steps:

adding a solvent, glacial acetic acid, a compound shown in a formula 2 and 2, 6-dichloro-4-trifluoromethylphenylhydrazine into a container, stirring and carrying out rotary evaporation, and extracting to obtain a crude product shown in a formula 3;

adding a solvent, alkali and the dried crude product of the formula 3 into a container, stirring, adjusting the pH value to acidity, and extracting after rotary evaporation to obtain a compound of the formula 1, namely the fipronil artificial hapten.

4. The method for preparing fipronil artificial hapten according to claim 3, which is characterized in that: the molar ratio of the 2, 6-dichloro-4-trifluoromethylphenylhydrazine to the compound shown in the formula 2 to the alkali is 1:1: 1.

5. A fipronil antigen characterized by: the structural formula is shown as a formula 4,

formula 4;

wherein n is less than or equal to 6;

the protein is BSA, HSA, KLH or OVA.

6. A method for preparing the fipronil antigen of claim 5, characterized in that: the fipronil artificial hapten of claim 1 is connected with a carrier protein through a coupling reagent to obtain a fipronil antigen;

the carrier protein is BSA, HSA, KLH or OVA.

7. The method for preparing fipronil antigen according to claim 6, wherein: the method comprises the following specific steps:

adding 10mg of fipronil hapten into DMF, adding 10-20 mg of EDC and 5-10mg of NHS, and uniformly mixing to obtain a premixed solution;

dissolving 5-10mg carrier protein in 2-10mL 0.1M NaHCO₃And mixing the solution with the premixed solution, stirring for reaction, and dialyzing to obtain the fipronil antigen.

8. An antibody against fipronil and its metabolites, characterized in that: the fipronil antigen of claim 5, which is used to prepare anti-fipronil and its metabolite antibody by immunological technique, monoclonal antibody preparation technique or phage display technique.

9. Use of the antibody against fipronil and its metabolites as claimed in claim 8 for the detection of fipronil and its metabolites.

10. The use of antibodies against fipronil and its metabolites in the detection of fipronil and its metabolites according to claim 9, wherein: the anti-fipronil and metabolite antibodies thereof are used in food safety detection kits, in-vitro diagnosis kits or microfluidic chips, and the food safety detection kits and/or the in-vitro diagnosis kits are colloidal gold immunoassay kits, chemiluminescence immunoassay kits, radioimmunoassay kits, enzyme linked immunosorbent assay kits or fluorescence immunoassay kits.

Technical Field

The invention belongs to the technical field of antibody preparation, and particularly relates to a fipronil artificial antigen, a preparation method and application thereof.

Background

Fipronil, a common name in English, is a pure white solid, is a pyrazole pesticide, has a wide insecticidal spectrum, and has a stomach toxicity effect on pests. The method is widely applied to the aspects of crop pest control, household pet parasite prevention and control, entertainment place environmental sanitation improvement and the like. However, fipronil residues can cause severe pollution to water, soil and the environment, thereby damaging the physiological health of beneficial organisms and even threatening the life safety thereof, and finally endangering human health and safety through the food chain. In 2017, a toxic egg event caused by fipronil is developed in Europe, and the development of the event highlights the importance of well monitoring and detecting the fipronil. In Chinese food safety national standard food, maximum limit of pesticide residues (GB 2763 ⁃ 2016) 2016, fipronil residues are the total of fipronil, fipronil sulfone and fipronil sulfoxide.

At present, the detection methods which are commonly used internationally are mainly physicochemical detection methods, such as High Performance Liquid Chromatography (HPLC), gas chromatography-mass spectrometry combined (GC-MS), liquid chromatography-mass spectrometry combined (LC-MS), ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry and the like, and the methods have high sensitivity and low detection limit, but are not suitable for rapid detection of a large number of samples because the required equipment is very expensive and the sample pretreatment is complex and time-consuming.

And the immunological method can well make up for the defects. The immunological detection method is based on antigen-antibodyThe specific binding principle is based on the detection method with high sensitivity and strong specificity established by various labeling technologies. At present, the fipronil immunodetection method is mainly based on an enzyme-linked immunosorbent assay (ELISA) of an anti-fipronil polyclonal antibody or a monoclonal antibody. The preparation method of the artificial antigen about fipronil which is currently authorized or announced in China mainly comprises the following steps: fipronil artificial hapten with publication number CN101100456A and a synthesis method thereof, antigen, antibody and application thereof, fipronil hapten compound with publication number CN101100457A, a synthesis method thereof and application thereof. Both of the above two patents relate to the synthesis and application of fipronil hapten, and the hapten synthesis method related to the invention is complex, the time required by the whole process is long, and the detection limit is high. The invention discloses an artificial fipronil antigen and antibody with publication number CN101100486A and application thereof, and relates to synthesis of the artificial fipronil antigen. The invention discloses an ELISA kit for detecting fipronil residue based on a nano antibody with the publication number of CN107607703A and application thereof, and the invention has the advantages that although the pretreatment time of a sample is short, a large amount of samples can be detected at one time, the detection limit and IC are limited₅₀And are also all higher.

Disclosure of Invention

In order to solve the technical problems, the invention provides an artificial fipronil antigen, a preparation method and application thereof, wherein an analogue of fipronil is used as a hapten to prepare the artificial antigen with better specificity, and on the basis, a high-specificity antibody for resisting the fipronil is prepared, so that the artificial antigen is applied to detection of fipronil residue.

The technical scheme adopted by the invention is as follows: an artificial hapten of fipronil, the structure is shown in formula 1,

formula 1;

wherein n is less than or equal to 6.

The method for preparing the artificial hapten of fipronil comprises the steps of chemically synthesizing 2, 6-dichloro-4-trifluoromethyl phenylhydrazine and a compound shown in a formula 2 to obtain a compound shown in a formula 3; then reacting the compound shown in the formula 3 with alkali to prepare a compound shown in a formula 1, namely fipronil artificial hapten;

formula 2;

formula 3;

preferably, the base is LiOH, NaOH or KOH.

The method comprises the following specific steps:

adding a solvent, glacial acetic acid, a compound shown in a formula 2 and 2, 6-dichloro-4-trifluoromethylphenylhydrazine into a container, stirring and carrying out rotary evaporation, and extracting to obtain a crude product shown in a formula 3;

adding a solvent, alkali and the dried crude product of the formula 3 into a container, stirring, adjusting the pH value to acidity, and extracting after rotary evaporation to obtain a compound of the formula 1, namely the fipronil artificial hapten.

Preferably, the molar ratio of 2, 6-dichloro-4-trifluoromethylphenylhydrazine, the compound of formula 2 and the base is 1:1: 1.

A fipronil antigen has a structural formula shown in formula 4,

formula 4;

wherein n is less than or equal to 6;

the protein is BSA, HSA, KLH or OVA.

The method for preparing the fipronil antigen comprises the steps of connecting the fipronil artificial hapten with carrier protein through a coupling reagent to obtain the fipronil antigen;

preferably, the carrier protein is BSA, HSA, KLH or OVA.

Preferably, the specific steps are as follows:

adding 10mg of fipronil hapten into DMF, adding 10-20 mg of EDC and 5-10mg of NHS, and uniformly mixing to obtain a premixed solution;

dissolving 5-10mg carrier protein in 2-10mL 0.1M NaHCO₃Mixing the solution with the premixed solution, and stirringReacting and dialyzing to obtain the fipronil antigen.

An antibody against fipronil and its metabolic product is prepared from fipronil antigen through immunizing technique, monoclonal antibody preparing technique or phage display technique.

The application of the antibody of fipronil and its metabolite in the detection of fipronil and its metabolite is provided.

Preferably, the anti-fipronil and metabolite antibodies thereof are used in a food safety detection kit, an in vitro diagnosis kit or a microfluidic chip, and the food safety detection kit and/or the in vitro diagnosis kit is a colloidal gold immunoassay kit, a chemiluminescence immunoassay kit, a radioimmunoassay kit, an enzyme linked immunosorbent assay kit or a fluorescence immunoassay kit.

The invention has the advantages and positive effects that: the preparation method of the fipronil artificial antigen is provided, the prepared high-specificity anti-fipronil antibody can be used for detecting fipronil and metabolites thereof, and the prepared anti-fipronil antibody has extremely high sensitivity; the residual fipronil is a serious hazard to food safety and causes great harm to human bodies. Therefore, the method has important significance for quickly detecting the fipronil and the metabolite thereof.

Drawings

FIG. 1 is a fipronil detection standard curve established by taking fipronil artificial antigen 1 as a coating antigen;

FIG. 2 is a fipronil detection standard curve established by taking fipronil artificial antigen 2 as a coating antigen;

FIG. 3 shows the results of the colloidal gold immunochromatographic assay for detecting different fipronil solution concentrations.

Detailed Description

The following description is made of embodiments of the present invention.

The invention designs a structural analogue of fipronil, takes the analogue as a hapten to prepare an artificial antigen with better specificity, and prepares a high specificity antibody for resisting the fipronil on the basis, so as to be applied to the detection of the residual quantity of the fipronil and metabolites thereof.

An artificial fipronil hapten, the structure of which is similar to fipronil, the fipronil structural analogue can highlight an antigenic determinant and has higher specificity, the structure is shown in formula 1,

formula 1;

wherein n is less than or equal to 6.

The method for preparing the artificial hapten of fipronil comprises the steps of chemically synthesizing 2, 6-dichloro-4-trifluoromethyl phenylhydrazine and a compound shown in a formula 2 to obtain a compound shown in a formula 3; then reacting the compound shown in the formula 3 with alkali to prepare a compound shown in a formula 1, namely fipronil artificial hapten;

formula 2;

formula 3;

wherein the base is preferably LiOH, NaOH or KOH.

The method comprises the following specific steps:

the method comprises the following steps: adding a solvent, glacial acetic acid, a compound shown in a formula 2 and 2, 6-dichloro-4-trifluoromethylphenylhydrazine into a container, stirring and carrying out rotary evaporation, and extracting to obtain a crude product shown in a formula 3;

step two: adding a solvent, alkali and the dried crude product of the formula 3 into a container, stirring, adjusting the pH value to acidity, and extracting after rotary evaporation to obtain a compound of the formula 1, namely the fipronil artificial hapten;

wherein, a crude product or the fipronil artificial hapten is obtained by extracting with ethyl acetate and water. The 2, 6-dichloro-4-trifluoromethylphenylhydrazine, the compound shown in the formula 2 and the alkali can be mixed in any ratio, and in order to improve the reaction efficiency and reduce the production cost, the preferable molar ratio is 1:1: 1.

N = 1, and the base is LiOH. H₂O is taken as an example, the method for preparing the fipronil artificial hapten can be carried out according to the following process,

the method comprises the following specific steps:

adding 5-50mL of ethanol, 1-10 mu L of glacial acetic acid, 20-100 mu L of ethyl acetoacetate and 0.5-5g of 2, 6-dichloro-4-trifluoromethylphenylhydrazine into a container, stirring and rotary steaming, and extracting by using ethyl acetate and water to obtain a crude product;

adding 50-100mL of ethanol, 20-60mL of water and LiOH & H into a container₂0.5-5g of O and the dried crude product, stirring, adjusting the pH value to acidity, performing rotary evaporation, and extracting by ethyl acetate and water to obtain the fipronil artificial hapten.

A fipronil antigen has a structural formula shown in formula 4,

formula 4;

wherein the content of the first and second substances,

the protein is BSA, HSA, KLH or OVA.

The method for preparing the fipronil antigen comprises the steps of connecting the fipronil artificial hapten with carrier protein through a biological coupling agent to obtain the fipronil antigen; the method comprises the following specific steps:

adding 10mg of fipronil hapten into DMF, adding 10-20 mg of EDC and 5-10mg of NHS, and uniformly mixing to obtain a premixed solution;

10mg of carrier protein was dissolved in 10mL of 0.1M NaHCO₃And mixing the solution with the premixed solution, stirring for reaction, dialyzing by PBS to obtain the fipronil antigen, and storing at the temperature of minus 20 ℃.

A fipronil antibody, a monoclonal or polyclonal antibody which is obtained by immunizing a mouse with fipronil antigen and can perform specific immunoreaction with fipronil. The fipronil antigen is mixed with the immunologic adjuvant and then used for injection; the immunological adjuvant is Freund's complete adjuvant, aluminum hydroxide adjuvant, alum adjuvant or liposome.

The fipronil antibody is applied to fipronil detection, the fipronil antibody is used for an in vitro diagnosis kit or a microfluid chip, and the in vitro diagnosis kit is a colloidal gold immunoassay kit, a chemiluminescence kit, a radioimmunoassay kit, an enzyme linked immunosorbent assay kit or a fluorescence immunoassay kit.

The following describes the scheme of the present invention with reference to the accompanying drawings, wherein experimental methods without specific description of operation steps are all performed according to corresponding commercial specifications, and instruments, reagents and consumables used in the examples can be purchased from commercial companies without specific description.

Example 1: synthesis of fipronil artificial hapten

To the flask were added 25mL of ethanol, 10. mu.L of glacial acetic acid, 2.95mL of ethyl acetoacetate, and 5g of 2, 6-dichloro-4-trifluoromethylphenylhydrazine, and the mixture was stirred for 3 hours, rotary-distilled, extracted with ethyl acetate and water, and dried.

Into the flask were added 80mL of ethanol, 40mL of water, and LiOH. H₂0.98g of O and the compound obtained after the previous step is dried are stirred for 4 hours, then the pH value is adjusted to acidity by HCl, and after rotary evaporation, extraction and drying are carried out, so that fipronil artificial hapten 1 is obtained, and the chemical structural formula is shown as follows:

。

example 2: synthesis of fipronil artificial hapten

To a flask, 25mL of ethanol, 5g of 2, 6-dichloro-4-trifluoromethylphenylhydrazine, 50. mu.L of glacial acetic acid, and 4.39g of ethyl 7-acetylheptanoate were added, and the mixture was reacted for 2 hours with stirring, and the ethanol was removed by rotary evaporation of the solvent, and the combined organic phases were extracted twice with ethyl acetate and water, dried over anhydrous sodium sulfate, and concentrated.

100mL of ethanol, 50mL of water and LiOH.H were added to the flask in this order₂Stirring 0.98g of O and the compound obtained in the previous step for 1.5 hours, adjusting the ph to acidity by using HCl, carrying out rotary evaporation on the HCl to remove ethanol, extracting twice by using ethyl acetate and water, combining organic phases, drying by using anhydrous sodium sulfate, and carrying out rotary evaporation to remove the solvent to obtain the fipronil artificial hapten 2, wherein the chemical structural formula is shown as follows:

。

example 3: preparation of fipronil artificial antigen

5mL of anhydrous DMF was taken in a brown vial, and 10mg of the fipronil artificial hapten 1 prepared in example 1 was weighed in DMF. 10mg of EDC and 5mg of NHS were added to the mixture under stirring, and the mixture was stirred at room temperature for 2 hours.

10mg BSA was weighed into 10mL 0.1M NaHCO₃To the solution, the above solution was added to the BSA solution. Stirring for 4 hours at room temperature, dialyzing with PBS, and packaging to obtain fipronil artificial antigen 1, and storing at-20 ℃.

In this embodiment, the carrier protein BSA may also be other carrier proteins, such as HSA, KLH, OVA, etc.

Example 4: preparation of fipronil artificial antigen

5mL of anhydrous DMF was taken in a brown vial, and 10mg of the fipronil artificial hapten 2 prepared in example 2 was weighed in DMF. 10mg of EDC and 5mg of NHS were added with stirring and stirred at room temperature for 2 hours.

10mg BSA was weighed into 10mL 0.1M NaHCO₃To the solution, the above solution was added to the BSA solution. Stirring for 4 hours at room temperature, dialyzing with PBS, and packaging to obtain fipronil artificial antigen 2, and storing at-20 ℃.

In this embodiment, the carrier protein BSA may also be other carrier proteins, such as HSA, KLH, OVA, etc.

Example 5: preparation of anti-fipronil monoclonal antibody

Mice of 6-10 weeks are selected for experiment, 5-10 mice are immunized, the prepared fipronil artificial antigen is mixed with equal volume of Freund complete adjuvant, after full emulsification, subcutaneous multi-point injection is carried out through the back and the abdomen, the dose is 5 ug/mouse, afterwards, every three weeks, the antigen and equal volume of Freund incomplete adjuvant are taken for full emulsification, then the intraperitoneal injection and the subcutaneous injection are carried out for boosting the immunity for four times, the intraperitoneal injection is carried out for the last time by the antigen with double dose, and splenocytes are taken for fusion after three days. And cloning and screening by 3-4 times of limiting dilution method to obtain cell strain, making the cell strain grow well after several times of in vitro passages and several times of cryopreservation resuscitation, stably secreting antibody, and making amplification culture for preparing antibody and storing in liquid nitrogen.

Example 6: preparation of anti-fipronil polyclonal antibody

Healthy male rabbits with the weight of 2-3 kg and the age of about half a week are selected for the experiment, three rabbits are immunized by each immunogen, and the rabbits are numbered from 1 to 3 respectively. The basic immunity of the experimental immunity measurement is 0.5-1.0mg/kg, the dosage of the boosting immunity is 1.0-1.5mg/kg, a proper amount of artificial antigen is diluted by normal saline, equivalent volume of Freund complete adjuvant (Freund incomplete adjuvant is adopted during boosting immunity) is added, and the mixture is fully emulsified until the mixture is not dispersed in water after being dropped. The method of combining subcutaneous multipoint injection on the back and intramuscular injection on the thigh is adopted. The back was immunized subcutaneously at 6 points, the thigh was injected intramuscularly at 2 points, 3 weeks later, and then the booster was given every 2 weeks later. From the third immunization, on day 8 after each immunization, blood was taken from the rabbit ear vein and the titer and specificity were determined.

Blood can be collected after the titer of immune serum is increased. The carotid artery blood sampling method is adopted in the experiment. After blood collection, the blood collection bottle is placed in an incubator at 37 ℃ for half an hour, after blood in the bottle coagulates, the blood clot is separated from the glass along the inner wall of the bottle by using an inoculation needle, then the bottle is placed in the incubator at 4 ℃ for 3 to 4 hours, after the blood clot shrinks, the blood serum is sucked into a test tube by using a capillary vessel, and the blood serum is separated out after centrifugation.

Example 7: establishment of ELISA detection method

Establishment of an ELISA detection method: coating: adding the fipronil artificial antigen 1/the fipronil artificial antigen 2 into an enzyme label plate according to a certain concentration, and incubating for 3 h at 37 ℃. Washing the plate: the wells were drained and the plates were washed 3 times with washing solution PBST. And (3) sealing: add blocking solution, 200. mu.L/well, block at 37 ℃ for 1 h, wash plate 3 times. Sample adding: respectively adding the fipronil standard substance or the sample to be detected into an enzyme label plate, wherein each well is 50 mu L; then adding anti-fipronil antibody with a certain concentration, incubating at 37 ℃ with 50 mu L/hole for 1 h, and washing the plate for 4 times. Adding an enzyme-labeled secondary antibody: adding goat anti-mouse or goat anti-rabbit enzyme-labeled secondary antibody with a certain concentration into an enzyme-labeled plate, incubating for 1 h at the temperature of 37 ℃ at a concentration of 100 mu L/hole, and washing the plate for 5 times. Color development: adding TMB developing solution, 100 μ L/well, and developing at 37 deg.C for 20 min. And (4) terminating: adding stop solution, 50 μ L/hole, and mixing. Reading: and (3) reading the OD value of each hole under the wavelength of 450 nm by using a microplate reader, calculating the inhibition rate, drawing a standard inhibition curve and calculating the concentration of fipronil in the solution to be detected.

Establishing an indirect competition ELISA detection method, establishing a standard inhibition curve according to an experimental result, and solving the IC according to the linear equation y = a lnx + b of the curve₅₀Value (concentration of fipronil for 50% inhibition) and IC₁₅Value (concentration of fipronil standard for 15% inhibition). With IC₅₀The value is taken as the sensitivity of the method, in IC₁₅The value is taken as the lowest limit of detection (LOD) for the method. Meanwhile, the result of the precision measurement also proves that the method has good repeatability. The standard curve is shown in fig. 1 and fig. 2. The result of the precision measurement also proves that the method has good repeatability.

Example 8: rate of cross reaction

Referring to the ELISA method, the fipronil standard is respectively changed into fipronil metabolite and structural analogues, fipronil sulfone, fipronil sulfoxide, trifluralin, flufenoxuron and teflubenzuron. The fipronil artificial antigen 1 is taken as an antigen, and the operation method of other steps is the same as ELISA. Different antigens and antigen structural analogues are used for making a competitive inhibition curve, and the cross reaction rate is calculated. The results are shown in Table 1.

TABLE 1 Cross-reaction of fipronil detection methods

From table 1 the results can be seen: the fipronil artificial antigen prepared in the invention has good affinity for fipronil and its metabolites, namely, fipronil sulfone and fipronil sulfoxide, and cannot be specifically combined with other fipronil structural analogues.

Example 9: sample detection

Matrix elimination: the invention can be used for detecting fipronil and its metabolite in vegetables, fruits, meat, eggs and milk. The sample to be detected is properly diluted after being extracted, and the fipronil artificial antigen 1 is taken as an antigen and can be directly used for ELISA detection. For example, vegetable samples can be extracted with methanol and then diluted with PBST for testing. After the detection method and the diluent are determined, an addition recovery experiment is carried out to verify the accuracy of the experimental conditions. The results are shown in Table 2.

TABLE 2 sample detection accuracy

Example 10: establishment of colloidal gold immunochromatographic assay

Colloidal gold-labeled antibody: with 0.1mol/L K₂CO₃1 mL of colloidal gold was adjusted to the optimum pH. And (5) uniformly mixing. Adding appropriate amount of antibody, mixing, and standing at room temperature for 15 min. Adding BSA blocking solution, mixing, standing at room temperature for 15 min, adding 10% PEG2000 water solution, mixing, standing for 15 min, centrifuging at 3000 r/min, removing precipitate, centrifuging at 10000 r/min, removing supernatant, and resuspending the precipitate with colloidal gold working solution.

Paving gold: the resuspended gold-labeled antibody solution is uniformly spread on a gold-labeled pad according to the concentration of 10-20 mu L/cm, and dried at 37 ℃.

Scribing a film: the fipronil artificial antigen 1 and the second antibody are respectively fixed on a cellulose membrane by using a membrane scribing instrument, wherein the fixed position of the artificial antigen is a detection line (T line), and the position of the second antibody is a quality control line (C line). After scratching, the film was dried at 37 ℃.

Assembling: respectively sticking a cellulose membrane, absorbent paper, a gold label pad and a sample pad on a PVC plate, then cutting into test strips with the width of 2-5mm by a full-automatic cutting machine, sealing, drying and storing.

Sample detection: 100 mu L of fipronil standard substance or sample diluent to be detected with different concentrations are respectively dripped on a sample pad of the test strip, and the negative control is PBS solution with the same volume. After a period of chromatography T, C line development was observed.

The prepared colloidal gold test strip is tested, fipronil standard substances with different concentrations are applied to samples, as shown in figure 3, the fipronil standard substances sequentially have the concentrations of 0.1ng/ml, 0.5ng/ml, 1ng/ml, 5ng/ml, 10ng/ml and 50ng/ml from left to right, and the detection lines are different in color development depth according to different fipronil concentrations, so that the detection method is proved to be successfully established and has higher sensitivity.

The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.