Difference between LOQ and LLOQ

[W Kruse]

Could someone explain what the difference is in LOQ and LLOQ? Is there a difference in determination? We use LOQ at S/N >10.

THanks,
Wanda

[JGK]

LLOQ is a term usially associated with Bioanalytical methods, in their guidance document http://www.labcompliance.de/documents/F ... 252fnl.pdf the FDA define it as:

Lower limit of quantification (LLOQ): The lowest amount of an analyte in a sample that can be quantitatively determined with suitable precision and accuracy.

it is not a value determined in the same way as LOD but more a determination of the practical working limits of the method in relation to acceptance criteria.

For bioanalytical methods the lowest calibration/QC STD is referred to as the LLOQ STD.