Which statement correctly defines MDL and LOQ?

Which statement correctly defines MDL and LOQ?

• A. MDL is the minimum concentration that can be quantified with acceptable precision; LOQ is the smallest detectable concentration with statistical confidence.
• B. MDL is minimum detectable concentration with statistical confidence; LOQ is the lowest concentration that can be quantified with acceptable precision.
• C. MDL and LOQ both refer to detection limits with equal precision.
• D. MDL is the highest concentration measurable; LOQ is the threshold for reporting results as detected.

Answer: (B)

In analytical testing, MDL and LOQ refer to two different thresholds. MDL is the smallest concentration that can be detected in a sample with statistical confidence, meaning you can say the analyte is present beyond background noise. LOQ is the smallest concentration that can be quantified with acceptable precision (and accuracy), so you can report an actual numerical value reliably. This matches the statement where MDL is the minimum detectable concentration with statistical confidence and LOQ is the lowest concentration that can be quantified with acceptable precision. For example, a method might reliably detect down to 0.2 units with confidence, but only quantify reliably from 0.6 units upward due to variability. The other descriptions mix up detection and quantification or imply equal precision for both, which isn’t correct.

In analytical testing, MDL and LOQ refer to two different thresholds. MDL is the smallest concentration that can be detected in a sample with statistical confidence, meaning you can say the analyte is present beyond background noise. LOQ is the smallest concentration that can be quantified with acceptable precision (and accuracy), so you can report an actual numerical value reliably.

This matches the statement where MDL is the minimum detectable concentration with statistical confidence and LOQ is the lowest concentration that can be quantified with acceptable precision. For example, a method might reliably detect down to 0.2 units with confidence, but only quantify reliably from 0.6 units upward due to variability.

The other descriptions mix up detection and quantification or imply equal precision for both, which isn’t correct.