The absorbance of a sample measured by ELISA is greater than the highest standard. What corrective action should be taken?

The absorbance of a sample measured by ELISA is greater than the highest standard. What corrective action should be taken?

• A. Extrapolate an estimated value from the highest reading
• B. Repeat the test using a standard of higher concentration
• C. Repeat the assay using one half the volume of the sample
• D. Dilute the test sample

Answer: (D)

When the absorbance of a sample in an ELISA (Enzyme-Linked Immunosorbent Assay) exceeds the highest standard, the appropriate corrective action is to dilute the test sample. This approach allows the absorbance reading to fall within the range of the standard curve, thereby enabling accurate quantification of the analyte. Dilution is essential because the standard curve is calibrated to a specific range of concentrations, and readings above this range can lead to inaccurate interpretations due to the nonlinear response of absorbance to concentration at high levels. By diluting the sample, it can be brought into the measurable range, allowing for precise determination of the concentration based on the established standard curve. Extrapolating an estimated value from the highest standard or repeating the test with a higher concentration standard may not provide reliable data because they assume a predictable linearity that might not hold true beyond the standard range. Reducing the sample volume in a repeated assay may likewise fail to account for the concentration issue and does not solve the problem of exceeding the calibration range. Therefore, dilution is the most effective and scientifically valid approach in this scenario.

When the absorbance of a sample in an ELISA (Enzyme-Linked Immunosorbent Assay) exceeds the highest standard, the appropriate corrective action is to dilute the test sample. This approach allows the absorbance reading to fall within the range of the standard curve, thereby enabling accurate quantification of the analyte.

Dilution is essential because the standard curve is calibrated to a specific range of concentrations, and readings above this range can lead to inaccurate interpretations due to the nonlinear response of absorbance to concentration at high levels. By diluting the sample, it can be brought into the measurable range, allowing for precise determination of the concentration based on the established standard curve.

Extrapolating an estimated value from the highest standard or repeating the test with a higher concentration standard may not provide reliable data because they assume a predictable linearity that might not hold true beyond the standard range. Reducing the sample volume in a repeated assay may likewise fail to account for the concentration issue and does not solve the problem of exceeding the calibration range. Therefore, dilution is the most effective and scientifically valid approach in this scenario.