Analytical Performance at Low Levels
*Marina Kondratovich, FDA/CDRH/OIVD 


A list of analytical studies for IVD FDA submissions will be provided and studies related to limit of blank (LoB), limit of detection (LoD) and limit of quantitation (LoQ) will be discussed in greater detail. The difference between LoB, LoD and LoQ, how these three limits are used in the reporting and interpretation of results will also be discussed. We will provide an overview of second edition of the CLSI document EP17-A2 “Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures” which includes classical, precision profile and probit approaches. For qualitative assays, the document CLSI EP12-A2 describes concentration C95, a concentration that produces 95% positive results when many replicates of a sample at that concentration are tested. We will discuss the relationship between LoD for quantitative assays and concentration C95 for qualitative assays.