R2 Std Era Std Er Estb Intercept Slope LOD ng mL-1 LOQ ng mL-1 API 0.99992 5964.87 8367.29 -1840.93 256586 3.3 9.8 Minipress 0.99992 6015.37 8438.13 -3265.90 256740 3.0 7.0 Serum 0.99994 5195.46 7287.99 -3829.48 256871 2.2 6.1 astandard error, bstandard error estimate

Table 2: Regression statistics of the proposed method with LOD, LOQ.