In order for the ELISA kit to determine accurate results, whether qualitative or quantitative, reagents must be prepared and assays performed in strict accordance with the prescribed methods. The main reagents have been prepared as described above. Other general reagents, such as coating buffer, washing solution, sample diluent, conjugate diluent, substrate working solution and enzyme reaction stop solution, etc., should not be taken lightly.
(1) Sample loading
In addition to coating in the ELISA kit, 45 loading is generally required. In the qualitative measurement, the accuracy of the amount of the sample is sometimes not emphasized, for example, it is prescribed as a drop. At this point, you should use the same diameter of the dropper to maintain an accurate loading posture, so that the volume of each drop of liquid is basically the same. In the quantitative measurement, the amount of sample loading is accurate. Dilutions of specimens and combinations should be prepared as specified. Add liquid to the bottom of the hole when loading, avoid adding it to the upper part of the hole wall, and be careful not to show bubbles.
(2) Insulation
In the ELISA kit, there is generally a secondary antigen-antibody reaction, that is, after the addition of the sample and after the addition of the combination, the temperature and time of the reaction should be in accordance with the specified requirements, and the heat preservation container is preferably a water bath to quickly balance the temperature. Each ELISA plate should not be stacked together. To avoid evaporation, the board should be covered or placed flat in a wet box with wet gauze on the bottom. The wet box should be metal and easy to transfer heat. If an incubator is used, the empty wet box should be placed in advance to balance the temperature, which is more important when the room temperature is lower. After the addition of the substrate, the reaction time and temperature are usually not strictly required. If the room temperature is higher than 20 ° C, the ELISA plate can be placed on the test bench in the dark, so that it can be observed from time to time. When the color of the control tube is appropriate, the enzyme reaction can be terminated.
(three) washing
Washing is not a reaction in the ELISA kit process, but it is the key to the success of the experiment. The purpose of washing is to wash away the substances in the reaction solution which are not bound to the solid phase antigen or antibody and the interfering substances which are non-specifically adsorbed to the solid phase carrier during the reaction. The adsorption of proteins by polystyrene to plastics is universal. Therefore, non-specific adsorption should be avoided as much as possible during the reaction determined by the ELISA kit, and this non-specifically adsorbed interfering substance should be washed away during washing. Adding a substance such as polysorbate to the dilutions and washings of the specimen and the conjugate is the right. Polysorbate is a polyoxyethylene sorbitan fatty acid ester which is a nonionic surface tension substance and is often used as a co-solvent. Polysorbate is numbered according to the type of fatty acid, and polysorbate 20 is combined with lauric acid, and is most commonly used in ELISA. It has a good washing effect and has the effect of reducing non-specific adsorption and enhancing antigen-antibody binding.
If the washing is not thorough, especially at the last time, if there is non-specific adsorption of the enzyme conjugate, the blank value will be raised. In addition, in the indirect method, if the non-specific IgG in the serum sample is adsorbed on the solid phase without being washed, it will also interfere with the enzyme-labeled antibody.
The ELISA plate can generally be washed by the following methods: 1 sucking the reaction solution in the well; 2 filling the plate with the washing liquid; 3 placing it for 2 minutes, slightly shaking; 4 sucking the inner liquid of the hole, or pouring the liquid to absorb water Pat the paper dry. The number of washings is generally 3 to 4 times, and sometimes even 5 to 6 times.
(4) Colorimetric
If the color of the negative control is extremely light, visual colorimetry can generally be used in qualitative determination. If the results are measured with a colorimeter, the accuracy is determined by the flatness and transparency of the ELISA plate and the quality of the colorimeter.
Salmon Fish,Fresh Salmon,Frozen Salmon,Salmon Sea Fish
ZHEJIANG RETRONX FOODSTUFF INDUSTRY CO.,LTD , https://www.retronxfoods.com