Assay Sensitivity

Assay Sensitivity designates the lowest concentration of an analyte reliably detected and quantified by an analytical method with acceptable accuracy and precision, expressed as the lower limit of detection or lower limit of quantification, determining whether a method can measure analyte concentrations at clinically or biologically meaningful levels.

The pharmaceutical industry optimises assay sensitivity throughout bioanalytical method development ensuring detection of drug concentrations at the low end of pharmacokinetic profiles, measurement of rare biomarkers predicting disease or treatment response, and identification of low-level impurities requiring safety assessment. Immunoassay sensitivity can reach femtomolar ranges using signal amplification. LC-MS/MS achieves high sensitivity for small molecules and peptides in complex matrices. Single molecule detection technologies approach attomolar sensitivity for biomarkers. Regulatory submissions include sensitivity data demonstrating methods adequately characterise drug exposure profiles over relevant pharmacokinetic periods. As precision medicine depends on measuring increasingly rare molecular signals, assay sensitivity continues advancing through improved detection technologies and optimised analytical strategies.