Fig. 1
Scatter plots with fits correlating methotrexate results (μmol/L) obtained by the reference method TBA-25FR with results obtained by TDX/FLX immunoassay at total samples (a), 24 h (b), 48 h (c), and 72 h (d) after the start of treatment. Assay results were very consistent between the two immunoassay systems, with good correlation total samples after the start of treatment (TBA-25FR = 1.05*TDX/FLX, −0.29, r = 0.99; Fig. 1a), 24 h after the start of treatment (TBA-25FR = 1.06*TDX/FLX, −1.31, r = 0.99; Fig. 1b), 48 h after the start of treatment (TBA-25FR = 1.00*TDX/FLX, +0.027, r > 0.99; Fig. 1c), and 72 h after the start of treatment (TBA-25FR = 1.09*TDX/FLX, +0.011, r > 0.99; Fig. 1d)