Quantitative Clinical Chemistry era
In the Quantitative Clinical Chemistry era (1920–1964), Otto Folin's leadership in standardizing laboratory assays established reproducible, small-sample workflows and elevated analytical precision as the core of diagnostic data. Vintilă Ciocalteu's Folin-Ciocalteu reagent enabled robust colorimetric protein and phenol assays, underpinning routine laboratory measurements. Donald D. van Slyke advanced spectrophotometric methods and blood gas analysis, institutionalizing corrected, expressible data and the role of quality controls in clinical decision making. Arne Tiselius's development of protein electrophoresis and Rudolf Sahli's hemoglobin determination techniques exemplified era-specific progress in protein fractionation and hemoglobin quantification.
Molecular and Immunodiagnostics era
In the Molecular and Immunodiagnostics era (1965-1999), clinical laboratories integrated molecular assays with immunodiagnostic methods, expanding measurable targets and enabling testing on archived and small-volume samples. Kary Mullis's development of PCR in the 1980s revolutionized diagnostic testing through primer-mediated DNA amplification, and Frederick Sanger's dideoxy sequencing provided the genetic readouts underpinning many targeted assays. In immunodiagnostics, Rosalyn Yalow and Solomon Berson established the radioimmunoassay framework, while Eva Engvall and Peter Perlmann introduced ELISA, standardizing robust immunodetection across laboratories. Antigen retrieval for tissue immunohistochemistry, as demonstrated by Shi SR and colleagues in the early 1990s, enabled reliable testing on formalin-fixed, paraffin-embedded specimens and underscored the era's emphasis on validation and analytic performance metrics.