Today marks the final day of July, and this month has been incredibly productive. Shanghai Hengyuan is proud to announce that our main product, the Guinea Pig ELISA Kit, is now available on the market. In today’s post, we’ll walk you through some common issues encountered during experiments and share best practices for maintaining accuracy and reliability in your testing procedures.
One important element in any ELISA experiment is the use of a critical value control serum. This type of control is typically set at the borderline between normal and abnormal values, often representing a weak positive result. For hepatitis B markers, defining this critical value should be based on clinical standards to ensure consistency in interpreting weakly positive results. The critical value control serum can act as a positive control within the kit, serving as a third control alongside the negative control. It helps detect even low-level reactions, ensuring no weak positives are missed.
For laboratories that require two quality control sera, there are several ways to prepare them. First, collect fresh serum that is free from hemolysis, jaundice, and bacterial contamination. Next, heat the serum at 56°C for 10 hours to inactivate any potential pathogens. After that, remove any precipitates by centrifugation or filtration. Then, dilute the serum using 10% calf serum or normal human serum (in PBS buffer). Using normal human serum is preferable since its composition closely resembles that of actual patient samples. Following this, filter and sterilize the solution, then aliquot it into single-use vials, seal them, and store at -20°C. Avoid repeated freeze-thaw cycles to maintain stability.
When preparing the control serum, consider the detection level required for your test. If additional concentrations are needed, adjust accordingly. For calibration, collect 20–30 test results, exclude those more than ±2 SD from the mean, and use this as a target value. Compare it with a known standard serum to ensure accuracy.
For three quality control sera, the serum provided by the Ministry of Health's clinical testing center can be stored at -20°C for up to six months. Once thawed, mix thoroughly before use, and store any unused portion at 4°C for up to five days. Avoid repeated freezing and thawing or self-packing. Laboratories should prepare new batches of homemade controls before the current batch runs out. Quality control serum must remain stable over time, with consistent potency and physical/chemical properties similar to patient samples to ensure effective monitoring throughout the testing process.
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