The closeness of agreement between the accepted value the found value. This can also be termed trueness.

When testing a sample, this is the highest value of analyte that is present that does not contain the analyte of interest.

This is the lowest value of an analyte that can be detected reliably above the limit of blank. This can be calculated as LOD = LOB +1.645(SD).

Selliah, N., Nash, V., Eck, S., Green, C., Oldaker, T., Stewart, J.,
Vitaliti, A., & Litwin, V. (2023). Flow cytometry method validation
protocols. Current Protocols, 3, e868. doi: 10.1002/cpz1.868

The lowest reliable value that can be detected with a high level of precision or %CV of ~25% or less, deeming the value to be quantifiable. When determining the LLOQ, the %CV of determination can be subjective. However, 25% is often used.

A qualification can be demonstrated as an abbreviated validation, where validations are much more involved and strict. Precision is often tested when officially “qualifying” an assay, but other aspects may be tested such as linearity, robustness, LOB, LOD, LOQ, or accuracy depending on the assay being qualified.

Qualifications should not be mistaken for validations.