What factors should I consider when choosing an ELISA kit?

There are many different types of ELISA kits available commercially for diagnosing hepatitis B, HIV/AIDS, TB, cholera, common cold, flu, and many other infectious diseases. The key is to choose the right kit for your specific purpose. 

These are the important factors to consider when choosing an ELISA kit 

1. Species being studied: Make sure the ELISA kit is validated for the species of your sample. Finding valid ELISA kits for classical models such as human, rat or mouse is comparatively easier than finding one for non-classical models such as monkeys as these kits are usually limited. In this case, selecting a kit with homology to your species is important.
2. The type of analyte being detected: You must first identify the type of analyte being detected. Large proteins with multiple epitopes, such as cytokines, are best detected using a sandwich ELISA, while small molecules such as haptens are detected using a competitive ELISA.
3. Type of antibodies: Check whether the kit uses monoclonal or polyclonal antibodies. Using polyclonal antibodies for capture and monoclonal antibodies for detection is often effective in sandwich ELISA. 
4. Sample type compatibility: Read the product descriptions and instructions to confirm the kit is compatible with your sample type, such as serum, plasma, or culture supernatants. Some sample collection methods, such as the use of EDTA or heparin, as well as factors like hemolysis and lipid content in the sample may affect assay performance.
5. Sensitivity Requirement: If you are unsure of the analyte concentration in the sample, it’s better to choose an ELISA kit with a broad detection range. High-sensitivity kits are the better option for samples with low analyte concentrations. 
6. Sample Size: Select a kit that matches the volume of your available sample. Kits typically require anywhere from 10µL to 100µL of the sample. If you have a very small or precious sample, make sure to choose an ELISA kit that requires only a small sample amount. 
7. Purpose of analysis: Choose between qualitative and quantitative ELISA based on your needs. Qualitative ELISAs offer simple positive/negative results for a sample, while quantitative ELISAs use a standard curve to measure the analyte concentration in a sample.
8. Recovery and Linearity Data: Analyze the recovery and linearity data provided by the manufacturer to ensure reliable detection. High recovery indicates the analyte is well-detected across different sample matrices, and linearity ensures consistent results at varying dilutions.
9. Detection System: ELISA kits offer different detection methods, including fluorescent, colorimetric, and luminescent systems. Choose the one that best suits your experimental setup, taking into consideration the enzyme label, substrate, and detection device.