Collection, Preservation, and Precautions for Serum Samples in ELISA Experiments
ELISA tests are commonly performed using serum samples. These samples can be collected using standard procedures, but care must be taken to avoid hemolysis. When red blood cells rupture, substances with peroxidase activity are released, which may lead to non-specific color development in HRP-labeled ELISA assays. Therefore, it's important to handle the samples carefully to prevent this issue. Serum samples should ideally be tested fresh. If contamination by bacteria occurs, the bacteria may contain endogenous HRP, leading to false positive results. For short-term storage (within 5 days), serum samples can be kept at 4°C. However, prolonged refrigeration may cause IgG polymerization, resulting in a higher background signal in indirect methods. For longer storage, it is recommended to store the samples at -20°C. After freezing, some proteins may concentrate or become unevenly distributed, so thorough mixing is essential before use. Bubbles should be avoided during handling. If the serum appears cloudy or has precipitates, it should be centrifuged or filtered before use. Repeated freezing and thawing can reduce antibody titer, so if multiple tests are planned, the serum should be aliquoted into small portions for storage. Proper aseptic techniques should be used during collection and storage, and preservatives may be added if necessary. In cases of incomplete anticoagulation, false positives may occur due to fibrinogen interference. To minimize this risk, it is recommended to use anticoagulants, especially heparin, whenever possible. **Additional Considerations:** 1. Avoid severe hemolysis. Hemoglobin contains heme groups that exhibit peroxidase-like activity. In HRP-based ELISA, high levels of hemoglobin can be adsorbed onto solid-phase surfaces and react with the substrate, causing unwanted color development. 2. During sample collection and serum separation, take precautions to prevent bacterial contamination. Bacterial enzymes may degrade antigens or antibodies, while certain bacteria like *E. coli* may produce enzymes such as β-galactosidase, which can interfere with enzyme-labeled assays. 3. If the serum is collected under aseptic conditions, it can be stored at 2–8°C for up to one week. If not, it’s better to freeze the sample. For long-term storage, keep it below -70°C. 4. Frozen serum samples should be handled carefully to avoid repeated freeze-thaw cycles, which can damage proteins and lead to false negatives. Avoid shaking or vigorously mixing the samples after thawing. 5. If the serum becomes cloudy or forms clumps due to bacterial growth during storage, centrifuge the sample and use only the supernatant for testing. By following these guidelines, you can ensure the quality and reliability of your ELISA results. Always prioritize proper handling, storage, and preparation of serum samples to avoid common pitfalls.3.5Mm To Rca Video Cables,Power Audio Cable,3.5Mm Audio Cable,Audio Extension Cable
ShenZhen Puchen Electronics Co., Ltd. , https://www.szpuchen.com