High background No signal Too much signal - whole plate turned uniformly blue Standard curve achieved but poor discrimination between points Poor duplicates Poor assay to assay reproducibility No signal when a signal is expected, but standard curve looks fine Samples are reading too high, but standard curve looks fine Very Low Readings Across the Plate Green color develops upon addition of stop solution when using streptavidin-HRP Edge Effects

The ELISA sample collection and storage conditions listed below are intended as general guidelines. Specific protocols may vary by cell line or tissue type. If storing sample for extended length of time, testing sample stability is recommended. Avoid repeated freeze-thaw cycles for all sample types.

The matrix refers to all components in a sample except the target analyte, such as proteins, lipids, salts, pigments, and small-molecule organic substances in the sample matrix. The matrix effect is a phenomenon where these matrix components interact with the target analyte or the analytical system, interfering with the separation, extraction of the target analyte or the detection response, and ultimately causing the analytical results to deviate from the true values. This type of interference is widely present in biological samples such as serum, plasma, cerebrospinal fluid, tissue homogenates, and cell culture media, and is a common cause of poor repeatability and inaccurate quantification in ELISA experiments.