Total error profiling of a proinsulin time-resolved fluorescence immunoassay

We applied total error profiling to evaluate the conversion of a known proinsulin (PI) enzyme-linked immunosorbent assay (ELISA) into a time-resolved fluorescence immunoassay (TRFIA). The formula and acceptance criteria proposed by the Ligand Binding Assay Bioanalytical Focus Group (LBABFG) of the American Association of Pharmaceutical Scientists (AAPS) were applied. We found that the expected dynamic range enlargement with TRFIA compared to ELISA ([0.5–240] versus resp. [0.7–98] pmol/L) is limited by an interference of C-peptide when present in the sample at high concentrations (>7000 pmol/L).