Linearity, range and lower limit of quantification (LLOQ)
REGRESSION
A twelve-point calibration curve was constructed by plotting the peak-area ratio (analyte:IS) against the concentration of the calibration standards. Determination of linearity was done using 3 calibration curves from each day (three separate days). The analysis requirement of linear regression was determined by the coefficient of determination (RTo determine the lower limit of quantification (LLOQ), 5 samples at LLOQ were analyzed for 3 batch runs on separate days. The analytical signal of LLOQ should be at least five times higher than the signal of the blank plasma or blank urine. The acceptable limits of accuracy should be within 80–120% and %CV ≤ 20.