How would you calculate a result that requires dilution due to high analyte concentration?

How would you calculate a result that requires dilution due to high analyte concentration?

• A. Divide by dilution factor.
• B. Subtract dilution factor.
• C. Add dilution factor.
• D. Multiply measured concentration by dilution factor; document steps and ensure results meet MDL/LOQ criteria.

Answer: (D)

When a sample is diluted to bring the analyte into the measurable range, you recover the original concentration by scaling the measured value on the diluted sample up by the dilution factor. The dilution factor is the total volume after dilution divided by the volume of the original sample. Multiply the concentration you read from the diluted sample by that dilution factor to get the undiluted concentration. For example, if you diluted 1 part sample with 9 parts diluent, the dilution factor is 10; a reading of 2 units in the diluted sample corresponds to 20 units in the original sample. You wouldn’t add, subtract, or divide by the dilution factor—the dilution process changes the amount of analyte, not the arithmetic relationship of the measured signal to concentration, so multiplication is the correct scaling method. After calculating, ensure the result falls within the method’s validated range and meets MDL/LOQ criteria, and document the dilution steps and factor used. If the final value is below MDL or LOQ, you may need to re-dilute differently or report as below LOQ, with appropriate notes.

When a sample is diluted to bring the analyte into the measurable range, you recover the original concentration by scaling the measured value on the diluted sample up by the dilution factor. The dilution factor is the total volume after dilution divided by the volume of the original sample. Multiply the concentration you read from the diluted sample by that dilution factor to get the undiluted concentration. For example, if you diluted 1 part sample with 9 parts diluent, the dilution factor is 10; a reading of 2 units in the diluted sample corresponds to 20 units in the original sample.

You wouldn’t add, subtract, or divide by the dilution factor—the dilution process changes the amount of analyte, not the arithmetic relationship of the measured signal to concentration, so multiplication is the correct scaling method. After calculating, ensure the result falls within the method’s validated range and meets MDL/LOQ criteria, and document the dilution steps and factor used. If the final value is below MDL or LOQ, you may need to re-dilute differently or report as below LOQ, with appropriate notes.